Welcome to the LIS Audio glossary of 12 Volt Mobile Electronic (Car & Pleasure Craft Audio) terms and definitions. This glossary, to date, is one of the most extensive online Car Audio write ups of terms used in the industry. From referencing generic and commonly used words and phrase’s to hard to find definitions for abbreviated terms commonly used to terms that have to deal with diagnostics and troubleshooting. This glossary was put together from many different credible sources, online and offline, to create an in depth list of Car Audio terms.
Read through and feel free to contact LIS Audio with any questions you may have about our 12 Volt Dictionary! Enjoy!
3G - Third Generation. A general term that refers to wireless air interface technologies offering increased capacity and capabilities delivered over the original 1G and 2G digital wireless networks. 3G network standards describe minimum peak speeds of at least 200kbits/s, but many of the implementations of 3G air interfaces are much faster than that (in the low 10-20Mbits/s).
4G - Fourth Generation. A general term that refers to wireless air interface technologies offering increased capacity and capabilities delivered above the 3G digital wireless networks. 4G network standards describe peak speeds of 100Mbits/s for high mobility communications (such as moving cars) or 1Gbits/s for stationary users.
802.11 - IEEE 802.11 is a set of standards for implementing wireless local area network (WLAN) device communication in the 2.4, 3.6, ad 5 GHz frequency bands. The 802.11 family consists of a series of over-the-air modulation techniques that use the same basic protocol. The protocols a, b, g, n, etc. are often simply generalized an 802.11xx indicating multiple compatibility. Wireless access using the 802.11 protocol is commonly called “Wi-Fi” by consumers and consumer products. (Also see Wi-Fi)
A - Refer to Attenuation
A2DP - Refer to Advanced Audio Distribution Profile
AAC - Refer to Advanced Audio Compression
Abrasives - Substances used to wear away a surface by friction. Common abrasives in mobile electronics fabrication include sandpaper, 3M Roloc discs, foam sanding pads and even lighter duty scrub pads to slightly remove surface finish top coats.
Accessories - Comfort, convenience and safety products not essential to the performance of a vehicle, such as audio, security products, floor mats and seat covers. In the business of automotive, anything not supplied with the basic vehicle in all instances for a given trim level or package is an accessory. Those accessories can be available from the vehicle manufacturer (OEM), from the vehicle dealer or from the aftermarket suppliers and retailers.
Accessory Power - Also called Accessory Power, refers to the position of the key in the ignition switched; wire showing 12 volts (+) when in the ignition switched position. Some newer vehicles do not offer a dedicated ignition switch. Also shows +12 volts in ACC and RUN positions, but no power in START position. Controlled by a positive switching non MUX ignition switch.
Acoustic Absorption - Measured in sabine units, Acoustic Absorption is the sound deadening property of any given dampening substance.
Acoustical Energy - Energy consisting of fluctuating waves of pressure referred to as sound waves.
Acoustic Feedback - A high pitched “squealing” sound when the output of an audio circuit is fed back in phase into the circuit’s input.
Acoustics - A science in dealing with the production, effects, and transition of sound waves through various mediums.
Acoustic Suspension - The inner air pressure of a closed or sealed subwoofer enclosure provides a sort of suspension that allows the diaphragm or cone to easily return to its resting position. This affect caused by the given characteristics under the optimal circumstances, can allow for greater power handling of the driver and is often referred to as acoustic suspension.
Active Arming - A method of arming a security system that requires some action, such as pressing a button on a remote transmitter or entering a code on a keypad.
Active Display - A step-up display feature that generates animated patterns for both segment and dot matrix LCDs that proceed the sequential display of information such as clock, Custom File titles and radio station frequencies.
Actuator - A type of motor for moving or controlling a mechanism or system. It is operated by a source of energy, usually in the form of an electric current, hydraulic fluid pressure or pneumatic pressure, and converts that energy into some kind of motion.
ADSR - An acronym that stands for Attack, Decay, Sustain, Release and is a means to replicate those respective elements of a sound. It is especially used in sound designing with electronic music instruments.
Advanced Audio Compression (AAC) - An encoding and variable compression scheme for digital music. AAC is the default compression scheme for iTunes when “ripping” music to the program or purchased music from the iTunes service. Also referred to as Advanced Audio Coding.
Advanced Audio Distribution Profile (A2DP) - Advanced Audio Distribution Profile – A Bluetooth profile for streaming 2 channels of 20Hz-20kHz audio from one Bluetooth device to another.
Advanced Television Systems Committee (ATSC) - A committee for digital television. The ATSC standards describe the way digital “over the air” television is broadcast to compatible digital television (DTV) receivers.
Advanced Television Systems Committee M/H (ATSC M/H) - ATSC digital television signals intended for mobile or handheld devices. To receive an ATSC M/H signals, the device must have an ATSC M/H tuner and the broadcaster must send ATSC M/H signals, which are often in addition ot their normal ATSC broadcast. The availability of ATSC M/H signals varies by city and region on broadcast support.
Aesthetics - A branch of philosophy dealing with the nature of art, beauty, and taste, with the creation and appreciation of beauty. It’s more scientifically defined as the study of sensory or sensori-emotional values, sometimes called judgments of sentiment and taste. More broadly, scholars in the field define aesthetics as "critical reflection on art, culture and nature.
Air Gap - The space between the top plate and the pole piece. This is where the voice coil sits.
Air Horns - A type of horn that uses compressed air instead of an electric diaphragm or voice coil to produce sound. These horns are usually driven by an electric air pump that receives its trigger from a host security system.
Air Interface - The operating system of a wireless network. Underlying technologies include AMPS, TDMA, CDMA, GSM, and iDEN with a host of derivatives built on the basis of those technologies. The air interface type(s) are often one or the other based on service provider.
Alarm Reset - The property of an alarm system that resets the alarm to an alarmed state after a preset period of time.
Aliasing Noise - The result of the sampling frequency not being at least double the highest analog frequency during the digital encoding of an analog signal.
Alignment - A class of enclosure parameters that provides optimum performance for a woofer with a given value of Q. In audio this typically refers to the different types and designs of subwoofer enclosures.
Alpha - Term used in sealed enclosure designs to mean the ratio of Vas to Vb, where Vb is the volume of the box you will build.
Alternating Current (AC) - The movement of a current that periodically switches polarity. As opposed to a direct current (DC), this flows in one direction.
Alternator - An electromechanical device that converts mechanical energy into electrical energy in the form of alternating current. Usually driven be by automotive internal combustion engine, and uses a magnetic field to produce the alternating current.
Alternator Whine - A siren like whining that occurs when engine RPM’s increase. The noise is often the result of a voltage differential created by more than one ground path between the audio system components or fatigued charging system components such as the alternator or battery.
Aluminum (Al) - Is a silvery white metal and the most abundant naturally occurring metal found beneath the Earths crust. Aluminum is nonmagnetic and does not easily ignite. The properties of aluminum that provide the most advantage to the audio world are it’s light weight, durable, electrical conduction, thermal conduction, and ability to resist corrosion. Aluminum has 59% electrical and thermal conductivity of Copper, which the two metals may be compounded to create a cheaper and less efficient conductor. Because it has one-third the density and stiffness of Iron and Steel, aluminum is used in making driver baskets, screws and bolts. It may also be found in use as outer casing to external filters, some amplifiers, terminals, and butt-connectors.
Ambience Synthesizer - A unit that produces an artificial ambience pattern; one that is used to create the impression of the listener and/or performer being in a particular performance space. Also known as an “effects processor.”
American Wiring Gauge (AWG) - Is a standardized wiring system also referred to as Brown & Sharpe wiring gauge, used since 1857 predominantly in the U.S. and Canada for the diameters of round, solid, nonferrous, electrically conducting wire. The cross section of the wire is important for determining its current-carrying capacity.
Ammeter - An instrument used for measuring the amount of current flowing in a circuit.
Amperage - A unit of electrical current; the force through which the energy is pushed through a conductor. Measured in Amperes, or Amps for short. Ohm’s Law symbol for Amperes is “I.”
Ampere (A) - Often referred to as Amps, is a unit of current named after French Mathematician and Physicist Andre-Marie Ampere whom is considered the father of electrodynamics. The measures of a constant current will be defined in amperes and the flow of charge through a circuit over a period of time will be defined in coulombs. In this way, amperes can be view as a flow rate, i.e. number of particles (charge) transiting per unit time, and coulombs simply as the number of particles.
Amplification - An increase in signal level, amplitude, or magnitude.
Amplifier - Is a device for increasing the power of a signal by use of an external signal source. The input and output current of an amplifier is typically measureable in voltage.
Amplitude - The maximum value of a periodically varying quantity. The measure of how much signal is contained in an alternating signal. Amplitude is typically expressed in units of Volts or decibels (dB).
Amplitude Modulation (AM) - Also known as AM Stereo, the encoding of a carrier wave by variation of it's amplitude in accordance with an input signal.
Analog - A way to represent data by means of continuously variable quantities. A control or circuit which continuously changes the level of a signal in direct relationship to the control setting. An electrical signal whose frequency and level vary continuously in direct relationship to the original acoustical sound waves (something that is analogous).
Analog Switch - A hardwire-oriented switch that only passes signals that are faithful analogs of transducer parameters.
Analog to Digital Convertor (ADC) - A circuit that converts an analog signal into a digital signal. With a continuous input signal the ADC will check the signal several time per second (sampling), assign values to the samples and represent it as a binary number (quantization and encoding).
Analogous - Alike in certain ways. Similar in function but not in origin or structure.
Anode - The electrically positive pole of an electronic device such as a semiconductor. A diode, for instance, has a positive and a negative pole; these are known as the anode and the cathode.
Antenna - An apparatus used for sending and receiving radio waves, usually constructed of metal. The best performance from an satellite, analog, or digital antenna will be when installed in line of sight with the sky.
Antenna Trimmer - An adjustment found on analog radios used to maximize AM reception. Turning this trimmer to the point where the sound is the loudest increases the sets signal to noise ratio optimizing performance.
Anti-theft Protection - Some stereos give you the option of setting up a security code. This is usually in addition to having a detachable faceplate. The security code is a three or four button combination, usually using the radio preset buttons, that has to be entered before the stereo will function. These anti-theft stereo security codes can be found on some manufacturer source units as well. A detachable faceplate lets you remove the control panel of your receiver easily, and take it with you when you leave the car. The stereo is useless to thieves without the faceplate, so the temptation to break in your car is greatly reduced. All but a handful of the receivers we offer come with a detachable face.
Aperiodic - Refers to a type of bass-cabinet loading. An aperiodic enclosure type usually features a very restrictive, (damped), port. The purpose of this restrictive port is not to extend bass response, but lower the Q of the system and reduce the impedance peak at resonance. Most restrictive ports are heavily stuffed with fiberglass, dacron or foam.
Arm - The term used to describe the act of causing a security system to reach a state in which it will protect the vehicle.
Armature - Generally refers to one of the two principal electrical components of an electromechanical machine–generally in a motor or generator, but it may also mean the pole piece of a permanent magnet or electromagnet, or the moving iron part of a solenoid or relay. The other component is the field winding or field magnet. The role of the "field" component is simply to create a magnetic field (magnetic flux) for the armature to interact with, so this component can comprise either permanent magnets, or electromagnets formed by a conducting coil.
Arming Delay - A term used to describe the elapsed time between the moment a security system is first told to arm and the moment it is actually armed. This normally applies only to systems that are passively armed, but it can apply to actively armed systems, as well.
Atom - A unit of matter, the smallest unit of an element, having all the characteristics of that element and consisting of a dense, central, positively charged nucleus surrounded by a system of electrons. The entire structure has an approximate diameter of 10*8 centimeter and characteristically remains undivided in chemical reactions except for limited removal, transfer, or exchange of certain electrons. Atoms with 1-3 electrons on the outer “shell” are considered conductors when the electrons break free.
Atomic Nucleus - Refer to “Nucleus”
Attenuate - To lessen the amount of force, magnitude, or value of something.
Attenuator - A device to decrease or increase the strength of a signal.
Audio Frequency (AF) - Also known as audible frequency, is characterized as a periodic vibration whose frequency is audible to the average human. It is the property of sound that most determines pitch and is measured in hertz (Hz).
Audio Frequency Spectrum - The band of frequencies extending roughly from 20 Hz to 20 kHz.
Audio Oscillator - A device that produces tones at specific frequencies for testing either equipment or entire systems.
Auto Electric - Automotive repair business specializing in electrical and lighting products for commercial and passenger vehicles, as well as in the repair/ replacement of failing electrical parts. Many retailers selling and installing car audio and security products can also perform these Auto Electric services because of their ability to troubleshoot vehicle electrical systems.
Audio Spectrum - The audible frequency range at which humans can hear. The audio spectrum spans from 20 Hz to 20 kHz and can be effectively broken down into 7 different frequency bands, with each having a different impact on the total sound. The break down of these 7 frequency bands is as follows; Sub-bass 20-60 Hz, Bass 60-250 Hz, Low Midrange 250-500 Hz, Midrange 500-2 kHz, Upper Midrange 2-4 kHz, Presence 4-6 kHz and Brilliance 6-20 kHz.
Audio/Video (AV) - AV is the abbreviation for audio/video and is frequently used as a generic term for the audio and video components and capabilities in vehicle, and home entertainment systems and related product descriptions and reviews.
Audio Video Remote Control Profile (AVRCP) - This profile allows for Bluetooth control and compatibility beyond that of the HP and HFP profiles. It allows the user control to play/pause and skip track without having to use the portable device or phone and may also display artist, title and album on the aftermarket stereo. Bluetooth media streaming and control via aftermarket stereo.
Auto Eject - Feature of a cassette player that ejects the tape when it has finished playing one side.
Auto Loud - Automatically provides low frequency boost for listening at low levels.
Auto Memory - Is a tuner feature that automatically finds the strongest stations in the local area, and places them in preset memories.
Automotive Aftermarket - Replacement or add-on purchases for a vehicle after its original sale, including parts, accessories, lubricants, fuel, appearance products and repairs. The Mobile Electronics Aftermarket (also referred to as “Car Audio”) is but one segment of the larger overall Automotive Aftermarket industry.
Auto Replay - Feature of a cassette player that automatically rewinds a tape when it has reached the end of one side, then begins to replay.
Auto Reverse - Feature of a cassette player that automatically plays the reverse side of a tape when one side has reached the end.
Auto Reset - The ability of a security system to automatically reset itself after being triggered.
Auto Stop - Feature of a cassette player that automatically shuts off power when a tape has reached the end of either side in any mode.
Automatic Gain Control (AGC) - A circuit that continuously adjust the recording amplifier gain to maintain a relatively constant recording level.
AUX - Refer to Auxiliary Input
Auxiliary Input (AUX) - An input on the face or rear of the receiver that enables you to connect a plug-and-play satellite radio tuner or portable music player (CD, MP3, or cassette) to the receiver. The input jack can be either Mini or RCA.
AV - Refer to Audio/Video
B - Refer to Magnetic Flux Density
BI - Electro-magnetic force factor.
BL - Driver motor strength.
Back-up Battery - A separate battery added to the security system as an alternate power supply to serve as a back up in case the vehicles main battery is disabled by a thief. Back-up batteries are typically the lead0acid gel cell type and are most effective when hidden from detection.
Baffle - In car audio this is the surface a driver is mounted to that separates the front wave from the back wave of the driver. An infinite baffle is simply the mounting surface of the driver when in a free air application.
Balance - The relative volume level between two channels, usually the left and right channels. May also refer to the relative volume between front and rear channels of an audio system. To make the same or equal.
Balanced - Referring to wiring: Audio signals require two wires. In an unbalanced line the shield is one of those wires. In a balanced line, there are two wires plus the shield. For the system to be balanced requires balanced electronics and usually employs XLR connectors. Balanced lines are less apt to pick up external noise. This is usually not a factor in home audio, but is a factor in professional audio requiring hundreds or even thousands of feet of cabling. Many higher quality home audio cables terminated with RCA jacks are balanced designs using two conductors and a shield instead of one conductor plus shield.
Ballast - An inductor is very common in line-frequency ballasts to provide the proper starting and operating electrical condition to power a fluorescent lamp, neon lamp, or high intensity discharge (HID) lamp. (Because of the use of the inductor, such ballasts are usually called magnetic ballasts.)
Ballast Wire - The name given to a special resistance wire used between the ignition switch and the engine’s high voltage coil. This wire is typically composed of a carbon compound instead of normal copper.
Bandpass Enclosure - An enclosure with dual chambers enclosing the entire subwoofer, the patent for a bandpass enclosure was issued to Andre d’Alton in 1934. Typically one chamber sealed and the other vented, while the vented enclosure acts as a high-frequency attenuator or low-pass filter controlling the dB per octave roll-off.
Bandpass Filter - A device which incorporates both high-pass and low-pass filters in order to limit and attenuate both ends of the frequency range.
Bandwidth - Refers to the “space” in the frequency response of a device through which audio and/or data signals can pass (between lower and upper frequency limits; in audio applications those points where the signal level has rolled off 3 dB).
Barium Ferrite - A type of magnetic material used widely in car audio speakers, subwoofers, and/or driver motor structures. The material is made from alloy with iron and barium for improved magnetic strength.
Basket - The “frame” or “carriage” that holds the components (Cone, Voice Coil, Motor Structure, etc.) of a subwoofer in place.
Bass - Is a word used to describe the low end frequencies played in music, normally considered to be between the 60 Hz to 250 Hz range. Most popular music uses bass to provide harmonic and rhythmic support (most modern music tracks bass signals are around 90-200Hz), usually playing the root or fifth of the chord and stressing the strong beats. Boosting the 250 Hz frequency can add a feeling of warmth to the bass without loss of definition.
Bass Blocker - Commercial name for auto-sound first order high pass crossovers (non-polarized capacitors), generally used on smaller speakers to attenuate low mid/low frequencies.
Bass Boost - Boost a given input signal feature, and is offered on some aftermarket source units and subwoofer amplifiers. Some amplifiers offer an externally mounted bass boost controller for convenience of lowering the bass level. The bass boost must be tuned into the audio system when turned to its peak volume, this way the user can back the volume down but not increase it.
Bass Reflex - A vented enclosure that allows control of rear radiated sound waves. The area and length of the opening(s) are critical to optimum low frequency performance.
Battery - An electrically connected group of cells, wired in series, that stores an electrical charge and supplies a direct current (DC).
BBE Processor - A signal processing circuit that provides improvements in imaging and spatial realism by altering the frequency and phase characteristics of portions of the input signal.
BCM – Refer to Body Control Module
Beaming - The tendency of a loudspeaker to concentrate the sound in a narrow path instead of spreading it.
Best Tuning Memory (BTM) - A feature in which the tuner selects radio stations by signal strength, and assigns them to presets in numerical order, according to their frequency value.
Bezel - The trim piece that often covers the exterior edges of a car stereo and other dash components. Typically made of plastic and attached to the dashboard as a factory dress piece.
Bessel Crossover - A type of crossover design characterized by having a linear or maximally flat phase response. Linear phase response results in constant time-delay (all frequencies within the passband are delayed the same amount). Consequently the value of linear phase is it reproduces a near-perfect step response with no overshoot or ringing. The downside of the Bessel is a slow roll-off rate. The same circuit complexity in a Butterworth response rolls off much faster (steeper).
Bi-Amping - Is the process of using two amplifiers, one on either side of crossover frequency ranges, i. e. one amplifier for lows and the other for highs. This setup may also be utilized to separate tweeters from speakers in an active crossover application, where the speakers are on one amp and the tweeters are powered by another. By-Amping is not entirely possible when using a passive crossover setup.
Bias - Known as an unbalanced sound level. An unbalanced sound level, often used in the term “side biased” where the left and right channels are not equally perceived by the listener, usually because they sit closer to one side or the other in the car.
Binary Digit (BIT) - The smallest unit of data in a digital signal represented by either a one or zero.
Binary Code - Information that is presented as a numeric bitstream of ones and zero's. The language of digital media.
BL - The magnetic strength of the motor structure. Expressed in Tesla meters, this is a measurement of the motor strength of a speaker. Think of this as how good a weightlifter the transducer is. A measured mass is applied to the cone forcing it back while the current required for the motor to force the mass back is measured. The formula is mass in grams divided by the current in amperes. A high BL figure indicates a very strong transducer that moves the cone with authority.
Bluetooth - A short-range protocol that allows wireless connections in the 2.4GHz spectrum between compatible devices with range of 30 feet. While it’s often associated with hands-free mobile phone usage, depending on the Bluetooth profiles of two devices, the applications can extend to virtually any kind of data or command exchanges wirelessly.
Bluetooth Profile - The specific operational characteristic intended to provide the scope of how a Bluetooth device behaves. Two Bluetooth devices must support compatible profiles to be able to connect, or “pair.”
Body Control Module (BCM) - Is a generic term for an electronic control unit responsible for monitoring and controlling various electronic accessories in a vehicle's body. Typically in a car the BCM controls the power windows, power mirrors, air conditioning, immobilizer system, central locking, etc. The BCM communicates with other on-board computers via the car's vehicle bus, and its main application is controlling load drivers – actuating relays that in turn perform actions in the vehicle such as locking the doors or dimming the salon overhead lamp.
Bojo Tools - A brand name of fiberglass reinforced plastic (FRP) pry tools that are “non marring” to sensitive vehicle panels and surfaces.
Boomy - Usually refers to excessive bass response, or peak in the bass response of a recording, playback, or sound reinforcement system.
Bottom End - Also known as Bass response, refers to the sound qualities of the lowest frequency ranges of a speaker or audio system.
Box Rise - The sum of the subwoofer(s) impedance and the additional acoustic impedance added by the enclosure and the vehicle.
Brain - Also known as the Control Unit, the common term used to refer to the main control unit of a security system.
Bridge-tied Load (BTL) - Is an output wiring configuration for amplifiers, a form of impedance bridging also known as bridged transformerless and bridged mono. The two channels of a stereo amplifier are fed from a common signal path, with one channel’s polarity reversed, often in used with subwoofers. This may double the voltage swing at the load as compared to using the same amplifier without BTL.
Bridging - Bridging combines left and right channels of an amplifier into a single, more powerful L+R mono channel. Bridging is common when using a multi-channel amplifier for a subwoofer application.
Brilliance - The range of audio frequencies between 6 kHz and 20 kHz that when boosted, can increase the sense of air and is responsible for sparkle, its composed entirely of harmonics.
Business Ethics - The study of proper business policies and practices regarding potentially controversial issues such as corporate governance, insider trading, bribery, discrimination, corporate social responsibility and fiduciary responsibilities.
Butterworth Filter - A filter with a pass-band with no ripple but usually sacrifices some steepness in attenuation.
Butyl - Is a synthetic rubber, copolymer of isobutylene with isoprene, produced by polymerization of about 98% of isobutylene with about 2% of isoprene. Butyl rubber has excellent impermeability, and the long polyisobutylene segments of its polymer chains give it great flex properties. This is typically used in driver excursion surrounds, sound deadening materials, and some sealants and caulks.
Buying Group - Consortium of businesses that buys in large quantities at discount prices.
Byte - Eight bits. It takes one byte to represent one letter of the alphabet.
c - Propagation velocity of sound at STP, approximately 342 m/s.
Cab - Acoustic compliance of air in the enclosure.
Cabin Gain - Also referred to as the “transfer function,” this is the build up of long pressure waves (bass notes) inside of the vehicle in which the music is playing. At sea level the speed of sound is 1127 ft/ per second, which at 40 Hz means the wave is approximately 28 ft long, since the typical vehicle cabin is near 12 ft in length (give or take depending on the vehicle) than it is possible to gain 12 dB’s simply from this function. The less air space inside of the vehicle cabin occupied by the subwoofers and enclosure will give the vehicle more cabin gain, and vice versa.
CAFE - Refer to Coporate Average Fuel Economy
Capacitance - The property exhibited by two conductors separated by a dielectric, where an electric charge becomes stored between the conductors.
Capacitor - Formerly known as a condenser is a passive two-terminal electrical component used to store energy in an electric field. The most commonly used capacitors are round and consist of a thin layer of insulating film (dielectric) sandwiched between two pieces of conductive foil material which build up an electrical field as energy and then released. Capacitors are used to filter out direct current and allow alternating current to flow through, smoothing out the output of power supplies, in the resonant circuits that tune radios to certain frequencies, temporarily storing and emitting alternating power, and many other ways. They are characterized by a single value, capacitance which can be measured in Farads.
There are two types of Capacitors commonly seen in Car Audio, Polarized and Non-Polarized. Polarized capacitor is an electronic device that stores energy and releases it when needed. Used in power supply applications. Polarized capacitors have specific terminals for positive and negative connections. Non-polarized capacitor is an electronic device that stores energy and releases it when needed based on the frequency of the signal. Used in passive crossover audio filtering applications. Non-polar capacitors do not have specific terminals for positive and negative connections.
California Air Resources Board (CARB) - The agency in California that is responsible for regulation and enforcement of vehicle emissions standards often described as more stringent than Federal EPA guidelines.
CAN - Refer to Controller Area Network
CARB - Refer to California Air Resources Board
Cas - Virtually the acoustical equivalent of Cms.
Cathode - The electrically negative pole of an electronic device such as a semiconductor. A diode, for instance, has a positive and negative pole; these are known as the anode and the cathode.
CEA - Refer to Consumer Electronics Association
Cell (Energy Storage) - A Single unit for producing DC electricity by electrochemical or biochemical action. A common 12.66V vehicle battery is composed of a number of individual cells connected together. Each cell is typically rated at 2.11 volts; a common automotive battery is composed of six separate two-volt cells.
Cell (Wireless Communications) - The basic geographic unit of wireless coverage. Also, shortened for generic industry term “cellular.” A region is divided into smaller “cells,” each equipped with a low-powered radio transmitter/ receiver. The radio frequencies assigned to one cell can be limited to the boundaries of that cell. As a wireless call moves from one cell to another, a computer at the Mobile Telephone Switching Office (MTSO) monitors the cal and at the proper time, transfers the phone call to the new cell and new radio frequency. The handoff is performed so quickly that it’s not noticeable to the callers.
Cell Site - The location where a wireless antenna and network communications equipment is placed in order to provide wireless service in a geographic area.
Cellular Digital Packet Data (CDPD) - Non-voice two-way communications transmitted in the cellular band.
Center Channel - In home theater, sound decoded from the stereo signal sent to a speaker mounted in front of the listener, specially designed to enhance voices and sound effects from a movie soundtrack. Used in car audio to help offset skewed stereo imaging due to seating positions in the automotive environment.
CDMA - Refer to Code Division Multiple Access
Channel (Audio) - The term used to describe a specific output or input in an audio system, usually as simple as “Left Channel” or “Right Channel” in stereo signals. Depending on the device (such as a signal processor or multi-channel source), there may be further designations of center, rear or low frequency channels.
Channel (Security) - The term used to describe the number of different functions possible for manipulating the buttons on a remote control transmitter.
Channel (Wireless Communication) - A frequency or band of frequencies assigned to a station or communications system. Also, a sub-circuit of a larger system (i.e. voice channel, control channel, paging channel, etc.).
Chassis - The metal frame of the vehicle often held together by various bolts and pinch welds.
Chebyshev Filter - A filter that has some ripple in the pass-band but has an initial attenuation slope which is steeper than a Butterworth filter.
Chirp - The term used to describe the brief sounding of a security system’s siren designed to indicate the state of arm of the system.
Circuit - Is a closed path in which electrons from a current or voltage source flow through, typically within wire or traces through which electrical current can flow. Inline of a circuit maybe found capacitors, resistors, transistors, relays, switches, inductors, diodes, transmission lines and many other components. They may typically conduct alternating and direct currents.
Circuit Breaker - Is an automatically operated electrical switch designed to protect an electrical circuit from damage due to current overload or short circuit. The basic function of the circuit breaker is to automatically break the current when detecting an overload or short in the circuit, which can then be reset to operate and continue the flow of current or voltage. Circuit breakers may vary in size and current capabilities (typically measured in Amperes) to fit any given application. The breaker reset process can be manually or automatic depending on the breakers design and application.
Clipping - Audible distortion that occurs when continuous power-to-peak power capabilities (headroom, ceiling) are exceeded.
Closed Cell Foam (CCF) - The trapped gas increases the insulation capability of the cured foam. The cured foam must be strong and of a medium density in order to lock in the gas bubbles. The foams strength, coupled with its closed cell nature, enable it to resist liquid water and function as a vapor retarder.
Closed Circuit - A continuous, unbroken circuit in which current can flow without interruption.
Closed Loop - A feedback path in a self-regulating control system. Unlike a standard open state trigger that needs to have a connection established to serve as a trigger, a closed loop trigger will act to trigger a security system when its loop (connection) is broken.
Cms - Is any given driver's mechanical compliance (reciprocal of stiffness), in m/N.
Cmes - The electrical capacitive equivalent of Mms.
Coaxial Driver - A speaker composed of larger cone for low range frequencies and a smaller cone or tweeter for higher frequencies aligned on the same axis. A crossover network is necessary to route the proper signals to each driver. These may be passive (usually included). If the speakers are bi-amplified, an active crossover will be used to route the proper range of frequencies to the respective amplifier channels.
Codec - A codec is a method of compressing and decompressing digitized sound. MP3 and WMA are examples of different codec’s. In the standard CD audio format, one minute of music takes up to roughly 10 megabytes. When converted to MP3, that same minute of music takes up only about 1 megabyte.
Code Division Multiple Access (CDMA) – A are interface channel access technology used by many wireless phones and services providers (including its CDMA2000 derivatives- RTT, EV-DO and EV-DV).
Coherence - Referring to sound quality, being aesthetically ordered, integrated and natural to the ear.
Coil - Often referred to as a Voice Coil, the coil itself is the copper former wrapped around the pole of the subwoofer. This coil acts as an electromagnet when electrical current is introduced.
Coloration - Any change in the characteristics of sound that reduces naturalness, such as an over emphasis of certain tones or frequencies.
Common Mode Rejection - The ability of the device to reject common-mode signals, i.e., those that appear simultaneously and in-phase on both inputs.
Compliance - The relative stiffness of a speaker suspension, specified as Vas.
Conductivity - Also known as electrical resistivity is a measure of how strongly a given material (conductor) opposes the flow of electrical current. Less electrical resistance through the conducting material means better conductivity of the conductor. The resistance of the conductor is traditionally measured in Ohms.
Constant (12V, B+) - A lead, wire, or connection point that shows positive 12 volts regardless of ignition key position or any other switch.
Consumer Electronics Association (CEA) - Catalyst to the dynamic technology industry, the Consumer Technology Association (CTA) accelerates growth and progress for the fast-paced economy. With leading market research, CTA educates members, and by establishing standards, CTA shapes the industry at large.
Continuity - The condition of being continuous.
Controller Area Network (CAN) - Also known as CAN-bus, is a computer network protocol and bus standard designed to allow microcontrollers and devices to communicate with each other and without a host computer. It was designed specifically for automotive applications but is now also used in other areas. CAN is also supported in the Linux Kernel since the 2.6.25 version. CAN-bus was originally developed in 1988 by Intel Corporation and Robert Bosch GmbH.
Copper (Cu) - Has a shiny reddish-orange color, and is ductile with very high thermal and electrical conductivity. The electrical and thermal conductive properties of copper are exploited in wire, amplifiers, subwoofers, heat sinks, and many other conductors recognized in the car audio industry. Copper maybe mixed with other alloys to provide a cheaper alternative (i. e. CCA grade wire).
Copper Clad Aluminum (CCA) - commonly abbreviated as CCAW or CCA, is an electrical conductor composed of an inner aluminum core and outer copper cladding.
Corporate Average Fuel Economy (CAFE) - The US government standards set requirements on automakers for improving the average fuel economy.
Coulomb - An amount of electrical charge which contains 6.24 X 10^18 (6,240,000,000,000,000,000) electrons. One coulomb per second past a given point is equal to 1 ampere of Current flowing.
Cross Interleave Read-Solomon Code (CIRC) - A combination of codes and interleaved data that make it possible to detect and correct errors in a compact disc system.
Crossover - Is a class of electronic filter that separates levels of signal frequency. Some drivers may not be capable of extending across the spectrum of frequency without increasing distortion, so it is necessary to incorporate an electronic crossover to filter out certain (possibly harmful) frequencies to said driver. The three most common classes of crossovers are passive, active, and mechanical.
Crossover Frequency - Often referred to as Crossover Point, is the frequencies at which a passive or active (electronic) crossover network divides the audio signals, which are then routed to the appropriate speakers.
Crosstalk - Also known as Channel Separation, is the amount of signal that leaks from one stereo channel into the other, or from one tape track into another. It is expressed in decibels, with the higher the value the better. Channel to channel crosstalk should be at least 30 db, with 40 db being very good.
Cu - Refer to Copper
Cutoff Frequency (F3) - In physics and electrical engineering, a cutoff frequency, or break frequency is a boundary in a system’s frequency response at which energy flowing through the system begins to be reduced (attenuated or reflected) rather than passing through.
Current (I) - The rate of flow of electricity, measured in amperes (amps).
D - Effective diameter of driver, in meters.
DAC - Refer to Digital-to-analog converter
Data-2-Data (D2D) - "Data to data" connection of an alarm/remote starter to bypass module.
Damping - The reduction of the magnitude of resonance by the use of some type of material, typically achieved by adding mass to an object. The damping material converts the energy of unwanted resonant vibrations into heat.
Damping Factor - This is a quality which defines how quickly the amplifier can stop a reproduced frequency such as a bass note. The higher the damping factor, the better the amp will control the woofer and help reduce overhang distortion. The damping factor of an amplifier is mostly dependent on the quality for the power supply which feeds the power amp.
Damping Material - Any material added to the interior of a speaker enclosure to absorb sound and reduce out-of-phase reflection to the driver diaphragm (cone). Usually acoustic fiberglass, polyester batting, or Polyfill is used in speaker enclosures.
dBr - The expression dBr is used to define signal at RF and AF frequencies. The symbol is an abbreviation for “decibel relative to reference level.” The dBr increment is based on the decibel, a logarithmic measure of relative signal strength.
DC - Refer to Direct Current
DC/DC Converter - A DC-to-DC converter is an electronic circuit or electromechanical device that converts a source of direct current (DC) from one voltage level to another. It is a type of electric power converter. Power levels range from very low (small batteries) to very high (high-voltage power transmissions).
Decade (dec) - One decade is a factor of 10 difference between two numbers (an order of magnitude difference) measured on a logarithmic scale. Along with the octave, it is a logarithmic unit used to describe frequency bands or frequency ratios. It is especially useful when referring to frequencies and when describing frequency response of electronic systems, such as amplifiers and filters.
Decibel (dB) - (1) A logarithmic scale used to denote a change in the relative strength of an electric signal or acoustic wave. It is a standard unit for expressing the ratio between power and power level. Using the logarithmic relationship for power PdB = 10*log[Pout/Pin], a doubling of electrical power only yields an increase of + 3dB. Increasing the power tenfold will yield an increase of +10 dB and is a doubling of a perceived loudness. The decibel is not an absolute measurement, but indicates the relationship or ratio between two signal levels. (2) SPL (sound pressure level) can be measured in dB. 0 dB represnts the threashold of normal human hearing, 130 dB represents the threashold for pain, 140 dB causes irreparable hearing damage, and 150 dB can casue instant deafness, anyting greater than about 192 dB can kill you.
Dedicated Fuse - A Fuse designated to supply power ad protection for one particular circuit only.
Destructive Interference - A phenomenon that occurs when speakers are 180 degrees out of phase. For example, what one speaker is trying to produce, the other speaker is fighting to cancel. One speaker’s wave is in the positive phase (pressure), while the other speaker’s wave is in the negative phase (rarefaction).
Detent Controls - A detent is a device used to mechanically resist or arrest the rotation of a wheel, axle, or spindle. Such a device can be anything ranging from a simple metal pin to a machine. The term is also used for the method involved. Detents are for example used to simply arrest rotation in one direction or to intentionally divide a rotation into discrete increments.
Deutsche Industrie Normen - DIN radio. A standard automobile radio body size. A DIN radio (single DIN) measures 2” X 7” and a double DIN measures 4” X 7”. When factory radio/CD players are replaced with aftermarket units, the DIN standard ensures compatibility. However, some new dashboard trims or bezels may be require alteration. DIN also refers to industrial standards that are used in the manufacture of many goods used in Europe, especially German made OEM automotive parts. Also refer to Single DIN and Double DIN.
Dial Up Network (DUN) – This is a profile extension of SPP and connects to a device through Bluetooth to a modem, whether a fixed-line or mobile phone data connection.
Diagnostic Trouble Code (DTC) - A five character code generated by the on board diagnostics system in 1996 and later vehicles indication the nature of a malfunction or problem.
Diaphragm - Also known as the cone, the part of a dynamic loudspeaker attached to the voice coil that moves and produces the sound. It usually has the shape of a dome or a cone.
Dielectric - a medium or substance that transmits electric force without conduction; an insulator.
Difference of Potential - The total numeric value measured between two points of different electrical potential. Difference of potential is commonly called “Voltage”.
DIFM - Refer to Do-It-For-Me
Diffraction - A change in the direction of a wave that is caused by the wave moving past or hitting an obstacle.
Diffusion - The scattering of sound.
Digital Media Files - Music which has been subjected to data compression — allowing users to store many hours of music as computer files. A growing number of in-dash CD receivers have the ability to decode and play recordable CDs (CD-Rs and CD-RWs) loaded with MP3, WMA, AAC, or WAV files. A single disc can hold up to ten hours of music.
Digital Multi-meter (DMM) - A digital multi-meter is a test tool used to measure two or ore electrical values- principally voltage (volts), current (amps) and resistance (ohms).
Digital Receiver - Digital media receivers are in-dash receivers that do not have CD players built in. Instead, they feature multiple inputs for devices like iPods, USB drives, SD cards, and so on.
Digital Sound Processor (DSP) - The process of analyzing and modifying a signal to optimize or improve its efficiency or performance. It involves applying various mathematical and computational algorithms to analog and digital signal to produce a signal that’s of higher quality than the original signal.
Digital Time Delay - A precise time delay of an electronic signal. Specifically an audio effect in which an input signal is digitally stored and played back after a given period of time. Typically utilized to simulate the acoustic properties of a particular type of environment.
Digital to Analog Converter (DAC) - A component or circuit that is used to derive or convert an analog signal from a digital one. This turns on/off pulses into analogue sound. CD players have DACs built in. Separate DACs can upgrade a CD player or other digital player/ recorder, or can be used with dedicated CD transports.
DIN - Refer to Deutsche Industrie Normen
Diode - An electrical component that enables easy electrical current flow in one direction and not the other.
Dipole - A speaker design which generates equal amounts of sound both forward and backward, with the two sounds being out of phase. Dipoles are often used as surround speakers. Similarly known as Bipole.
Direct Current (DC) - Electrical current flowing in only one direction.
Discharge - An electric discharge is the release and transmission of electricity in an appliedelectric field through a medium such as a gas.
Distortion - Refers to the deforming of a waveform at the output of a device as compared with the input, usually due to overload, creating a distorted or “dirty” signal. While electrical or audio distortion is typically unwanted and avoided, it is frequently used in controlled situations in audio to create certain desirable effects, particularly with electric guitars and amplifiers.
DIY - Refer to Do-It-Yourself
DMM - Refer to Digital Multi-meter
Do-It-For-Me - This refers to customers who use professionals to perform maintenance and repair work on their vehicles, including installation of their mobile electronics product (audio, security, convenience, safety, etc.).
Do-It-Yourself - This refers to consumers who perform maintenance and repair work on their own vehicles, including installing their own mobile electronic equipment.
Dome Light - The common term used to describe the overhead (or headliner) mounted interior courtesy light. The circuit is often a connection point for vehicle security to monitor any entry into the passenger compartment.
Dome Tweeter - a high frequency speaker driver with a dome-shaped diaphragm typically comprised of metal or silk.
Door Lock Solenoid - The proper name for the electric bi-directional actuator used to provide powered control of the vehicle door locks. Also called Door Lock Actuator.
Doppler Sensor - Another name for a spatial type sensor, also commonly called a radar sensor.
Double DIN - So-called "double DIN" receivers are two times the height of DIN-size receivers, which typically works out to 4" tall. These receivers are also shallower in depth and slightly wider. In many cases, these receivers re also equipped with DVD players and navigation systems.
Double Pole Double Throw (DPDT) - A term used to describe a switch or relay that has two separate poles or contacts and can throw or make electrical contact with two separate stationary contacts simultaneously.
DPDT - Refer to Double Pole Double Throw
Dress - The arrangement of signal and wiring for optimum circuit operation, cosmetic appeal, and protective routing. Wiring that is well dressed is neat and orderly and much easier for another installer to sort through when troubleshooting is necessary.
Driver - 1) A transducer in a loudspeaker that converts electrical signals into sound pressure waves. 2) A computer program that controls an attached device or piece of hardware.
DSP - Refer to Digital Sound Processor
DTC - Refer Diagnostic Trouble Code
Dual Band - A wireless phone or mobile communication device that works on more than one spectrum frequency, e.g., in the 800 MHz frequency and 1900 MHz frequency bands.
Dual Mode - A wireless phone or mobile communication device that works on both analog and digital networks.
Dual Reflex Bandpass Enclosure - Bandpass enclosures can be divided into two basic types: single reflex and dual reflex. In a single reflex design the rear chamber is sealed and the front chamber is ported, while in a dual reflex design the front and rear chambers are both ported. The chambers will typically have a simple ratio that helps tune the bandpass of the output frequency of the enclosure, for example a 2:1 or 3:1 ratio.
Dual Voice Coil (DVC) - A dual voice coil driver allows for more wiring configurations. Depending on the application and the impedance of the driver it can be wired up or down to pair with multiple drivers.
DUN - Refer to Dial Up Network
Duty Cycle - An engineering term used to describe the actual time (or frequency) that a circuit or device operates. A pulsing alarm output that is on for seven-tenths of a second and off for three-tenths of a second would have a 70% duty cycle.
DVC - Refer to Dual Voice Coil
Dynamic Range - 1) The ratio (in dB) between the loudest peak and the softest level of a song or recording. 2) The ratio (in dB) between the softest and loudest possible levels a device or system can provide without distortion.
E - Refer to Exa
Earth - European terminology often given to the electrical ground or chassis ground potential.
EBP - Refer to Efficiency Bandwidth Product
Echo - The distinct repetition of an initial sound, caused by the reflection of the sound waves upon a surface. We recognize a sound as an echo when the distance between the source and the reflection is far enough apart that we can detect the time delay between one and the other. Essentially, reverberation is the combination of many echoes occurring too rapidly to hear each individually. In the studio, echoes can be reproduced acoustically or simulated by a digital signal processor.
Echo Chamber - An enclosed room designed with reflective, non-parallel surfaces for the purpose of creating acoustic echoes (reverberation).
ECM - Refer to Engine Control Module
ECU - Refer to Electronic Control Unit
EDGE - Refer to Enhanced Data Rate for Global Evolution
Edit - To change one or more parameters of a recorded sound after the fact. This can take many forms, including “punching in” a section of the music that is re-recorded to replace the original version; altering the shape/size of waveforms graphically; changing the sequence of playback; and many others. Analog editing would typically involve splicing the magnetic tape on which the audio signals were recorded. These days, almost all editing in the studio is done via computer using a digital audio workstation (DAW).
Effect Loop - An effects loop is a series of audio effects units, connected between two points of a signal path (the route that a signal would travel from the input to the output); usually between the pre-amp and power amp stages of an amplifier circuit, although occasionally between two pre-amp stages.
Efficiency – The measurement of a loudspeaker or amplifier’s ability to convert input power to output power (work). Formula : Efficiency = (power out/ power in) X 100. Efficiency is always expressed as a percentage.
Efficiency Rating - the loudspeaker parameter that shows the level of sound output when measured at a prescribed distance with a standard level of electrical energy fed into the speaker (usually recorded as XdB @ 2.83V input signal from 1 meter of distance. However, a driver with a high efficiency rating needs a larger box to play a lower frequency than a driver with a lower efficiency rating.
Efficiency Bandwidth Product (EBP) - is a number which shows the trade-off between efficiency and bandwidth of a driver. It is useful in determining if a driver is suited for a sealed or vented box and is also used to determine suitability for horn loading.
EL Backlight - Electroluminescence Backlight is a solid state phenomenon which uses colored phosphors, not heat, to generate light. EL backlights are very thin, lightweight and provide an even light. They are available in a variety of colors, with white being the most popular for use with LCDs.
Electret -A dielectric plate that is designed with permanent polarity, allowing it to function similarly to a magnet. (“Electret” comes from the words “electricity” and “magnet.”) Used in some microphone types in place of a capacitor (condenser).
Electrical Current - a path in which electrons from a voltage or current source flow. The point where those electrons enter an electrical circuit is called the "source" of electrons.
Electronic Serial Number (ESN) - The serial number of an electronic device.
Electrolyte - The name for the mixture of diluted sulfuric acid found in standard lead-acid vehicle storage batteries.
Electrolytic Capacitor - A capacitor with a negative and positive terminal that passes only alternating current. Electrolytics are available in polarized and non-polarized configurations. Non-polarized (NP) capacitors are useful as inexpensive crossovers, blocking low frequencies from passing through to mid- or high-frequency speakers. Polarized capacitors have specific positive and negative poles. Polarized capacitors are used for storing and releasing energy.
Electromagnet - A soft metal core made into a magnet by the passage of electric current through a coil surrounding it.
Electromagnetic Field (EMF) - A field of magnetic energy put out because of current traveling through a conductor.
Electromagnetic Interference (EMI) - Also referred to as radio-frequency interference (RFI) when in the radio frequency spectrum, is a disturbance generated by and external source that affects an electrical circuit by electromagnetic induction, electrostatic coupling, or conduction.
Electromagnetic Radiation Detector (EMR Detector) - A tool used to find the source of low-frequency electromagnetic interference known as electromagnetic radiation, or EMR.
Electromotive Force (EMF) - Denoted with “E” and measured in volts. This is the voltage developed by any source of electrical energy such as a battery or dynamo. It is generally defined as the electrical potential for a source in a circuit. A device that converts other forms of energy to electrical energy supplies an EMF to a circuit.
Electron - An electron is a negatively charged component of an atom. Electrons exist outside of and surrounding the atom nucleus. Each electron one unit of negative charge and has a very small mass as compared with that of a neutron or proton.
Electronic Shock Protection (ESP) - An ESP system tries to get lean sound output while external shocks exist. ESP does not clear noises caused by scratched or dirty CD’s. This feature may also be referred to as Electronic Skip Protection.
Electrostatic Loudspeaker (ESL) - An electrostatic loudspeaker is a loudspeaker design in which sound is generated by the force exerted on a membrane suspended in an electrostatic field.
EMF - Refer to Electromagnetic Field or Electromotive Force
EMI - Refer to Electromagnetic Interference
Emergency Override - A button or switch installed in the vehicle is used specially to override or disarm a security system in the event that the primary means is unavailable or disabled.
EMR Detector - Refer to Electromagnetic Radiation Detector
Enclosure - An artificial or natural barrier that seals off an area. In car audio an enclosure is typically a cabinet constructed for a subwoofer or speaker. Subwoofer enclosures are typically made from wood such as, Medium Density Fiber (MDF) board and Birch wood for the most air tight seal, you may also see different types of acrylics used in marine applications. Prefabricated enclosures are made to fit generally any subwoofer of the size offered in an amount of air space that is fairly universal for subs of that size and can come in many different general alignments. A custom subwoofer enclosure is typically constructed to the specifications of the component being used in the application or to fit the area given for the subwoofer placement.
Enhanced Data Rate for Global Evolution (EDGE) - A GSM-development path for delivery of data, delivered at rates up to384 Kps. The standard is based on the GSM technology platform and uses the TDMA approach.
Engine Disable - A means, either electrical or mechanical, of preventing the vehicle’s engine from either starting or running. The most common variety of engine disable uses a simple automotive relay to inhibit either the starter or the ignition.
Entry Delay - The time interval a security system waits before sounding the alarm after a vehicle’s door has been opened.
Environmental Protection Agency (EPA) – The federal agency that regulates motor vehicle emissions compliance standards in the United States. Also refer to CARB.
Envelope - The collective term for the four elements of the lifespan of a sound: Attack, Decay, Sustain and Release (ASDR). The envelope of a sound describes how a sound or audio signal varies in intensity over a period of time.
EPA - Refer to Environmental Protection Agency
Equalization - The act of making equal or uniform. Equalisation, leveling. Human action, human activity, act, deed - something that people do or cause to happen. The process of balancing, reconciliation. Getting two things to correspond
Equalizer - A built-in EQ lets you tailor the sound to your listening tastes and to your vehicle's acoustics. Receivers with built-in EQs will have one or more equalizer "bands" in addition to standard bass and treble controls. These equalizer "bands" usually have fixed center frequencies and bandwidths (although some may be adjustable).
More sophisticated built-in EQs offer parametric equalization, which allows you to set the amount (in dB) by which a certain frequency band is boosted or cut — and determine the width and/or center frequency of this band. This gives you extremely precise control of the tonal balance in your vehicle.
Equalized Presets - Preset EQ curves are stored tone settings — boosting and cutting different frequencies can make big changes in the way your music sounds. Preset EQ curves are stored in memory, and are easily activated. If you listen to a wide variety of music, these presets are useful for making dramatic tonal changes instantly. (For example, you could use one EQ preset with heavy bass boost for rap or reggae, and a second preset with flat bass and a slight midrange/treble boost for jazz. This saves you from constant readjustment of the tone controls.)
Equal Loudness Contours - A drawing of several curves showing how loud the tones of different frequencies would have to be played for a person to say they were of equal loudness. Refer to Fletcher-Muson Curves
ESN - Refer to Electronic Serial Number
ESL - Refer to Electrostatic Loudspeaker
European Tuning - The European tuning interval of .05 MHz is different from the US tuning interval of .2 MHz. If a CD receiver also has European tuning, it is compatible with the European scale and can be used in many European countries.
EV-DO - Refer to Evolution-Data Optimized
Evolution-Data Optimized (EV-DO) - Also known as Evolution-Data Only. EV-DO is a wireless air interface standard based on CDMA technologies and is part of the CDMA 2000 family. The primary use for an EV-DO capable network is delivering wireless internet access to mobile users.
Evolved High Speed Packet Access (HPSA+) – A CDMA based air interface in late 3G/ early 4G applications. HPSA+ also uses MIMO multi-antenna transmission technology.
Exa (E) - A prefix meaning 1018 or 1,000,000,000,000,000,000
Exit Delay - The name given to the amount of time a security system waits once it’s given a command to arm. Exit delays are usually found on non-remote security systems that rely on keypads or the ignition switch to arm. This delay gives the operator time to exit the vehicle before the system arms.
Expertise - Expert skill or knowledge in a particular field.
External Regulator - Also referred to as a voltage regulator, it is designed to automatically or sometimes manually maintain a constant voltage level. A voltage regulator may be a simple feed-forward design or may include negative feedback. It may use an electromechanical mechanism, or electronic components. An external regulator is typically used in car audio to regulate the voltage of the engine alternator.
F3 - A -3dB cutoff frequency, in Hz
Fade - The act of minimizing or maximizing the volume of the vehicle stereo to the front or rear, and vice versa.
Fader - A fader is a control that allows you to balance the sound in a four-speaker system from front to rear. When used with a balance control, you can adjust the sound level from front to rear, and from right to left.
Farad (F) - The basic unit of capacitance. A capacitor has a capacitance of 1 Farad when a charge of 1 votl across the capacitor produces a current of 1 ampere through it. Named after Michael Faraday. There are one million micro-farads (mF) in 1 Farad.
Fb - Enclosure resonance (usually for bass reflex systems), in Hz
Fc/ Fcb - System resonance (usually for sealed box systems), in Hz
Federal Communications Commission (FCC) - The U.S. government agency that overseas and regulates electronic communications.
FET - Refer to Field-effect Transistor
Fidelity - A term used to describe the accuracy of the recording, reproduction, or general quality of audio processing.
Field-effect Transistor (FET) - a transistor that uses an electric field to control the electrical behavior of the device. FETs are also known as unipolar transistors since they involve single-carrier-type operation. Many different implementations of field effect transistors exist.
Filter - An active or passive circuit or device designed to block a certain frequency or range of frequencies. Often any electrical circuit or mechanical device that removes or attenuates energy at certain frequencies.
Firewall - Is the part of the automobile body (unibody or body-on-frame) that separates the engine compartment from the passenger compartment (driver and passengers). It is most commonly a separate component of the body or, in monocoque construction, a separate steel pressing, but may be continuous with the floorpan, or its edges may form part of the door pillars.
FLAC - Refer to Free Lossless Audio Codec
Flashing Lights - A term used to describe the interfacing of the vehicle's parking lights, dome light, emergency lights, etc., with a security system so that the lights flash by the security system.
Flat Response - Also referred to as Flat Frequency Response, is an output signal in which fundamental frequencies and harmonics are in the same proportion as those of the input signal being amplified. A flat frequency response would exhibit relatively equal response to all fixed-point frequencies within a given spectrum.
Fletcher Munson Curves - Similar to Equal Loudness Contour curves, this is a drawing of several curves showing how loud the tones of different frequencies would have to be played for a person to say they were of equal loudness. A set of curves that depict the uneven frequency response of human hearing that are extremely dependent upon relative loudness. The curves show the human ear to be most sensitive to sounds in the 2 kHz to 4 kHz area. This means sounds above and below 2-4 kHz must be louder in order to be heard just as loud. For this reason, the Fletcher-Munson curves are referred to as “equal loudness contours.”
Floating Ground - A non-common grounding point. A point of ground that does not share the same ground point as any other component in the vehicle. A singular ground point.
Flux - The flow of magnetic energy in a circuit.
Flux Density - the magnitude of a magnetic, electric, or other flux passing through a unit area.
Flux Capacitor - A Flux Capacitor is typically used to leap through time and other forms of time travel. In our time the Flux Capacitor is known to be powered with Plutonium. The Plutonium is used by the on-board nuclear reactor which then powers the Flux Capacitor to provide the needed 1.21 Gigawatts of Electrical Power. Once properly installed into the time machine the Flux Capacitor will need to reach 88 mph (142 km/h) to activate time travel.
FM - Refer to Frequency Modulation
FM Mono Sensitivity - This figure tells you how well a CD receiver can pick up FM radio signals. The smaller the number, the greater the ability to pick up weaker stations. Expressed in decibel femtowatts (dBf).
FM Stereo Separation - A measure of the ability of an FM tuner to re-create a vivid stereo effect. Measured in dB (decibels), the higher the figure the better.
FOB - Free on Board. The term designating that the purchaser pays freight from the time the shipment is placed aboard a truck or train. Legal title for the goods passes to the buyer at this time and location. Not to be confused with the electronic vehicle key referred to as a fob.
Fob - Refer to Key Fob
Focus Lens - The lens in the optical block of a compact disc player which focuses the laser light onto the surface of the disc.
Focus Servo - The circuit which keeps the laser light correctly focused on the pit area of the disc.
Free Air - Which means of free air. Air not under restraint (as by pressure or flow). Normal atmospheric air.
Free Air Resonance (Fs) - Driver free air resonance, in Hz. This is the point at which driver impedance is maximum. "This parameter is the free-air resonant frequency of a speaker. Simply stated, it is the point at which the weight of the moving parts of the speaker becomes balanced with the force of the speaker suspension when in motion. If you've ever seen a piece of string start humming uncontrollably in the wind, you have seen the effect of reaching a resonant frequency. It is important to know this information so that you can prevent your enclosure from 'ringing'. With a loudspeaker, the mass of the moving parts, and the stiffness of the suspension (surround and spider) are the key elements that affect the resonant frequency. As a general rule of thumb, a lower Fs indicates a woofer that would be better for low-frequency reproduction than a woofer with a higher Fs. This is not always the case though, because other parameters affect the ultimate performance as well."
Free Air Response - The frequency at which a speaker will naturally resonate.
Free Lossless Audio Codec (FLAC) - An audio format similar to MP3, but lossless, meaning that audio is compressed in FLAC without and loss in quality.
Frequency - The number of occurrences of a particular event within a certain amount of time. In audio and acoustics, frequency specifically refers to the number of complete cycles a vibration or waveform makes in a second, measured in cycles per second, or Hertz (Hz). In sound, frequency determines what we hear as pitch. The longer the wavelength, the fewer the cycles per second, and the lower the pitch.
Frequency Modulation (FM) - A method of sound synthesis in which the frequencies generated by one oscillator (the carrier) are altered by the output of one or more additional oscillators (operators) to create a diversity of harmonically rich sounds.
Frequency Response - A term that describes the relationship between a component’s input and output with regard to signal frequency and amplitude.
Front-stage - This typically refers to the speakers in the front of a vehicles sound-stage. Typically just the front vehicle cabin speakers, as opposed to the cabin rear speakers.
Fs - Refer to Free Air Resonance
Full-range - A speaker designed to reproduce all or most of the sound spectrum within human hearing (20Hz - 20KHz).
Full Wave Rectification - A circuit which converts an AC voltage into a pulsating DC voltage. It uses two diodes of which one conducts during one half cycle while the other conducts during the other half cycle of the applied AC voltage.
Fundamental Frequency - The original frequency component of a harmonic series.
Fundamental Tone - the tone produced by the lowest frequency component of an audio signal.
Fuse - A device designed to provide protection for a given circuit or device by physically opening when the current being drawn through it exceeds its designed rating.
Fusible Link - Designed to perform the same task as a fuse, but resembles a wire. Fusible links are commonly used in ignition switches and other high-current circuits.
Gain - Refers to the degree of signal amplification.
GAP - Refer to Generic Access Profile
Gauge - The diameter of a wire, size. The higher the number, the thinner the wire.
GEM - Generic Electronic (Control) Module
General Packet Radio Service (GPRS) - A packet technology approach that enables high-speed wireless Internet and other GSM-based data communications. It makes very efficient use of available radio spectrum for transmission of data.
Generator - A rotating machine that produces DC electricity. Also an electronic device used for converting DC voltage into AC of a given frequency and wave shape.
Generic Access Profile (GAP) - This profile defines the generic procedures related to the discovery of Bluetooth devices. It also defines procedures related to use of different security levels. Often this is thought of as the path of how two compatible Bluetooth devices “shake hands” and connect.
Generic Object Exchange Profile (GOEP) - This profile defines the basic requirements for Bluetooth devices intended for exchanging data in applications like synchronization, file transfer, or “pushing” data from one device into another, particularly in PDAs or PDA type phones. Also it’s used in imaging and printing Bluetooth transfer applications.
Giga - Prefix meaning 109 or 1,000,000,000 (1 billion in the US).
Gigabit Video Interface (GVIF) - A type of digital video signal, originally developed by Sony, that is used between devices such as navigation systems and an in-dash video screen.
Glass Sensor - A device designed to detect the sound of breaking glass or metal to glass contact, thus triggering a security system. Also called sound sensors, glass-break sensors, or sound discriminators.
Global Positioning System - A system of 24 satellites maintained by the US government orbiting the earth that each broadcast unique position data to compatible GPS receivers. Data from at least three satellites must be received to triangulate the exact longitude and latitude (X-Y) location of the GPS device. A fourth GPS satellite is necessary to accurately determine elevation/altitude (Z).
Global System for Mobile Communication - The United States offers GSM in the 1800 MHz bandwidth. Many network providers use GSM.
GOEP - Refer to Generic Object Exchange Profile
Golden Ratio - A ratio of height to width to length, where the width is approximately 1.6 times the height, and the length approximately 2.6 times the height. First calculated by the ancient Greeks, this ratio (known mathematically as “phi”) is used as an optimal ratio in many applications, including room dimensions and studio design (to achieve “optimal acoustics” in the room), and even in the design of certain acoustic instruments.
Gold Plate - This process is often used in electronics, to provide a corrosion-resistant electrically conductive layer on copper, typically in electrical connectors and printed circuit boards. ... Both the nickel and gold layers can be plated by electrolytic or electroless processes.
Googol - A googol is the number 10100, that is, 1 followed by one hundred zeroes.
GPRS - Refer to General Packet Radio Service
GPS - Refer to Global Positioning System
Gross Vehicle Weight (GVW) – The total weight of the loaded vehicle, including chassis, body and payload. Also known as Gross Vehicle Weight Rating (GVWR).
Ground - An electrical line with the same electrical potential as the chassis of the vehicle, most commonly negative 12 volts DC.
Ground Loop - The condition created when two or more paths for electricity are created in a ground line, or when one or more paths are created in a shield or an audio cable. This can create undesirable noise such as a high pitched whine when the vehicle is running or pops and clicks when other devices are used in the vehicle.
Ground Loop Isolator (GLI) - In an electrical system, a ground loop or earth loop occurs when two points of a circuit intended to be at ground reference potential are at different potentials.
Ground Potential - In electrical engineering, earth potential rise (EPR) also called ground potential rise (GPR) occurs when a large current flows to earth through an earth grid impedance. In an automobile this is the electrical potential of the vehicles chassis, specifically the chassis of the alternator when the vehicle is running. A circuit, terminal or chassis is said to be at ground potential when it is used as a reference point for other potentials in the system.
Ground While Running (GWR) - This is a circuit on a remote start or security system that sees ground while the vehicle is running.
Group Delay - The group delay of a filter is a measurement of the average delay of the filter as a function of frequency. It is the negative first derivative of a filter's phase response.
GSM - Refer to Global System for Mobile Communication
GWR - Refer to Ground While Running
GVIF - Refer to Gigabit Video Interface
Hy - Refer to Henries
Hands Free Profile (HFP) - The HFP allows more control and access, than Headset Profile (HF), to mobile phones via Bluetooth. The aftermarket products have many benefits, one being the flexibility of display and control options as well as the amount of phones that can pair to a single vehicle kit, as well as software upgrades or updates that may ensure future compatibility with new devices or profiles.
Harmonic - The overtones and undertones that define the acoustic difference between two sounds with the same fundamental frequency.
Harness - The universal name for a bundle or loom of wires that compose the wiring for a system.
HDCP - Refer to High-bandwidth Digital Content Protection
HFP - Refer to Hands Free Profile
Headroom - The difference between the highest level present in an audio signal and the maximum level an audio device can handle without noticeable distortion. A greater amount of headroom reduces the chances for unwanted distortion in an audio system.
Headset Profile (HP) - The most basic Bluetooth user profile. This profile allows the call to be accepted or terminated (hung up) and may also include a volume control.
Heat Sink - A heat sink (commonly spelled heatsink) is a passive heat exchanger that transfers the heat generated by an electronic or mechanical device to a fluid medium, often air or liquid coolant, where it is dissipated away from the device, thereby allowing regulation of the device’s temperature at optimal levels.
Heat Shrink - a shrinkable plastic tubing used to insulate wires, providing abrasion resistance and environmental protection for stranded and solid wire conductors, connections, joints and terminals in electrical work.
Henries (Henry/Hy) - The measurement for inductance. Coils (low pass filters) are measured in millihenries as in 6.4 mHy (6.4 millihenries).
Hertz (Hz) - The unit of frequency within a specific period, such as alternating or pulsing current; 1 Hz = 1 cycle per second.
HID Bulb - Refer to High Intensity Discharge
High-bandwidth Digital Content Protection (HDCP) - This is a specification developed by Intel to address digital rights management. HDCP is used with HDTV signals over DVI (optional) and HDMI connections (mandatory) to prevent unauthorized duplication of copywritten material by inhibiting the unauthorized distribution of digital video material through copying. It consists of data "keys" incorporated in the digital content together with proprietary encryption (scrambling) circuitry and software in the various video components (tuner, TV, DVD player, etc.) that handle HDTV.
High Definition Multimedia Interface (HDMI) - Now up to version 1.3, this digital video interface allows high definition video (up to and in excess of 1080p/60) and audio (up to 8 lossless channels) to be transmitted over a single cable. Except for some proprietary solutions (such as Impact Acoustics RapidRun Digital cables) HDMI cannot be terminate din the field and must be purchased in the correct lengths. Cables can be made of copper (limited to ~30 feet without electronic signal boost and equalization) or fiber optic, with the latter able to reach almost unlimited distances.
High Frequency - This refers to radio frequencies in the 3-30 MHz band. In audio it usually refers to frequencies in the 5-10 kHz band.
High Intensity Discharge (HID) - A type of electrical gas-discharge lamp which produces light by means of an electric arc between tungsten electrodes housed inside a translucent or transparent fused quartz or fused alumina arc tube. HID lamps, or bulbs are generally demand more power and often need what is referred to as a ballast to amplify the input voltage of the bulb. These types of bulbs are very sensitive and are often recommended to be handled wearing clean gloves to avoid it being exposed to the oils on human skin.
High Pass Filter (HPF) - A network of components which attenuate all frequencies below a predetermined frequency selected by the designer. Frequencies above cutoff are passed without any effect.
Hiss - To make or emit a sharp sound like that of the letter “S” prolonged, as a snake does, or as steam does when forced under pressure through a small opening.
HDMI - Refer to High Definition Multimedia Interface
Horn - In audio this refers to a loading deice when part of a bass enclosure, or a directional device when used with a high-frequency driver or compression driver. In security this refers to the built-in factory horn in the vehicle. Factory horns can be of the diaphragm type, voice coil type, or air-pump driven type (air horn). All types of horns can be interfaced to a security system.
Horsepower - A unit that is used to measure the power of engines and motors. One unit of horsepower is equal to the power needed to lift 550 pounds one foot in one second. This unit has been widely replaced by the watt in scientific usage; one horsepower is equal to 756 watts.
HP - Refer to Headrest Profile
HPF - Refer to High Pass Filter
HPSA+ - Refer to Evolved High-Speed Packet Access
Hum - An audio noise that has a steady low frequency pitch. To utter a sound like a long “M”. To make a buzzing noise of a flying insect. To make musical tones with closed lips.
Hz - Refer to Hertz
IASCA - International Auto Sound Challenge Association
ICE - Refer to In Car Entertainment
iDEN - Refer to Integrated Digital Enhanced Network
Ignition #1 - Refers to a source of power in the vehicle (controlled by a positive switching, non MUX ignition switch) that has +12VDC on it when the ignition keys is in the RUN position and START positions, but has no power in the ACC position.
Ignition #2 - Refers to a source of power in the vehicle (controlled by a positive switching, non MUX ignition switch) that has +12VDC on it when the ignition is in the RUN position, but has no power in the ACC or START positions.
Ignition #2 is not to be confused with electrical function of the ignition switch with terminology many remote starter instructions use to describe their second, sometimes third primary ignition switch connections. In most cases, from a remote starter standpoint - the Ignition #2 and ACC wiring form the vehicle both get connected to the remote starter’s “Accessory” outputs because they don’t need to sty powered while the vehicle starts (whereas Ignition #1 circuits do) and that’s often the only differentiation the remote starter makes with the way its output wiring is labeled.
Ignition Interlock - A device designed to prevent the vehicle’s ignition circuit from operating typically by separating one or more starter wires. This device is installed to prevent drinking and driving. The hand held part of the device will have a breathalyzer attached in order to test the alcohol level of the driver before the vehicle is allowed to start and run. Laws and regulations of ignition interlock systems may very state to state due to the laws surrounding them.
Ignition Kill - A device designed to prevent the vehicle’s ignition circuit from operating. An ignition kill device can work by either interrupting one or both of the primary wires leading to the ignition coil or by shorting out (grounding) the ignition coil’s positive primary wire. Also called “Ignition Disable”.
IM - Refer to Intermodulation
Image Rejection - The rejection of the same signals that can be received at two or more points on the dial of a tuner by a single radio station (ghost, images) . Image Rejection is expressed in decibels, the higher the number the better.
Imaging - The width and definition of a sound stage. Instruments should appear to be coming from their correct positions, relative to the recording.
IMD - Refer to Intermodulation Distortion
Impact Sensor - A sensor designated to detect various degrees of impact or vibration applied to the vehicle and then produce an output to trigger a security system.
Impedance (Z) - In audio this is a measurement of the resistance to the audio current by the voice coil of the speaker. Also refer to Nominal Impedance. When it comes to the electrical side, impedance is the dynamic resistive opposition offered by a device or circuit to the flow of alternating current (AC).
In-Car Entertainment (ICE) - Also called In-vehicle infotainment (IVI), is a collection of hardware and software in automobiles that provides audio or video entertainment. In car entertainment originated with car audio systems that consisted of radios and cassette or CD players, now includes automotive navigation systems, video players, USB and Bluetooth connectivity, Carputers, in-car internet, and WiFi. Once controlled by simple dashboards knobs and dials, ICE systems can include steering wheel audio controls and handsfree voice control.
Inductive Coupling - Radiated noise that is transmitted through a magnetic field to surrounding lines.
Inductance (L) - The property of an electric conductor or circuit that causes an electromotive force to be generated by a change in the current flowing or any other nearby conductors by mutual inductance. These effects are derived from two fundamental observations of physics: a steady current creates a steady magnetic field described by Oersted’s law, and a time-varying magnetic field induces an electromotive force (EMF) in nearby conductors, which is described by Faraday’s law of induction. According to Lenz’s law, a changing electric current through a circuit that contains inductance induces a proportional voltage, which opposes the change in current (self-inductance). The varying field in this circuit may also induce an EMF in neighboring circuits (mutual inductance).
Inductor - Also referred to as a Choke or Coil, this is an electrical component in which impedance increases as the frequency of the AC increases; also known as “coils” that are used in passive crossovers. Inductors are rated in Henries.
Infinite Impulse Response Filter (IIR) - Also referred to as IIR Filter, is a digital filter employing a single stage, through which the signal is passed repeatedly to achieve the desired processing effect. Offers simplicity of design and lower cost than the FIR type.
Infinite Baffle - A loudspeaker baffle of (theoretically) infinite space that has no openings for the passage of sound from the front to the back of the speaker.
Infrared Sensor - A type of spatial sensor that uses infrared energy to detect an object (a hand, arm, or body) entering a protected area. Also refer to Spatial Sensors.
Infrasonic - Refers to sounds or signals whose frequencies are below the normal human hearing range, generally considered to be 20 Hertz.
Input - In audio this is the high-level (speaker) or line level (RCA) signal connections that run into one component from another system component. In security this is any wire on a security system or remote starter designed to accept a signal from some outside source such as the vehicle’s wiring. Door trigger, hood trigger, trunk trigger, foot brake trigger and sensor trigger wires are all inputs.
Input Sensitivity Control - Adjusts the amount of input signal being fed to the amplifier stage to reduce distortion. Also referred to as “Gain.”
Instant Trigger - The term used to describe any trigger input on a security system that is designated to cause the system to respond instantly when triggered.
Insulation - A material that electrically isolates a conductor or thermally isolates an object from its surroundings.
Integrated Digital Enhanced Network (iDEN) - A specialized mobile technology that combines two-way radio, telephone, text messaging and data transmission into one digital network. Introduced by Motorola and used by AirTel Montana, Nextel Communications, Nextel Partners, and Southern LINC Wireless, among others.
Integrity - The expected durability or sturdiness of an installed component or connection.
Intermodulation (IM) - In audio also referred to as Intermodulation Distortion or IMD, is the amplitude modulation of signals containing two or more different frequencies, caused by nonlinearities in a system. Also refer to Intermodulation Distorotion.
Intermodulation Distortion (IMD) - Also referred to as IM Distortion, Intermodulation or IM, is the amplitude modulation of signals containing two or more different frequencies, caused by nonlinearities in a system. The intermodulation between each frequency component will form additional signals at frequencies that are not just at harmonic frequencies (integer multiples) of either, like harmonic distortion, but also at the sum and difference frequencies of the original frequencies and at multiple of those sum and difference frequencies.
In-vehicle infotainment (IVI) - Also referred to as In-Car Entertainment (ICE), is a collection of hardware and software in automobiles that provides audio or video entertainment.
Inventory Turns/Turnover - The number of times inventory is replenished within a particular time, calculated by dividing the cost of goods sold by the average inventory for the period.
Isobaric - Having constant or equal pressure. In audio this is the name of a subwoofer enclosure alignment, also referred to as a “Push-Pull” enclosure. The isobaric configuration was first introduced by Harry F. Olson in the 50’s, and refers to systems in which two or more identical woofers (bass drivers) operate simultaneously with a common body of enclosed air adjoining one side of each diaphragm. In practical applications, they are most often used to improve low-end frequency response without increasing cabinet size, though at the expanse of cost and weight.
Isobarik Enclosure - enclosure where one woofer is buried in the enclosure and a second is mounted up against the first and wired in reverse polarity (there are other variations for Isobarik designs), but this one works best. This allows the effective Vas of both drivers working in this push-pull configuration to be half that of a single identical driver mounted normally. Very small enclosures may be constructed as a result, with increased power handling. Less efficient than other designs, but the push pull configuration greatly reduces second order harmonic distortion. The name Isobarik comes from a term that means "constant pressure". See push-pull.
ISO-DIN Mounting - Refers to a mounting system in which the headunit is mounted behind the dash panel with side brackets, employing factory installed trim panels.
Jacket - The outer covering on a cable or wire that may provide electrical insulation and/or resistance to abrasion, chemicals, and moisture.
Jams - Tunes, rocks, hits, sounds good, etc.
Japanese Industrial Standards Committee (JISC or JIS) - A Japanese agency that establishes and maintains standards for equipment and components.
Jewel Case - The hard plastic case that contains a compact disc.
JISC - Often called JIS, refer to Japanese Industrial Standards Committee
Joule - A derived unit of energy or work, named after English physicist James Prescott Joule. I is equal to the energy expanded (or work done) in applying a force of one Newton through a distance of one meter (1 Newton Meter or Nm), or in passing an electric current in one ampere through a resistance of one Ohm for one second.
Jump - To provide a temporary circuit around a component or other circuit.
Junk - Discarded or useless; of no value.
K - Refer to Kilo
KCL - Refer to Kirchhoff’s Current Law
Key Fob - An electronic vehicle key that allows the vehicle to sense the key via a proximity sensor. They most commonly come with keyless entry and other remote commands built onto the fob as well.
Keypad - A panel usually made of metal or plastic with numbered push-buttons (like a touch-tone telephone) designed to provide access to certain types of security or communications systems.
kHz - Refer to Kilohertz
Kilo (k) - A prefix meaning thousand.
Kilohertz (kHz) - 1 kHz equals one thousand hertz or 1000 cycles per second. Formerly called kilocycles (kc).
Kirchhoff’s Current Law (KCL) - A law stating that the total current entering a point or junction in a circuit must equal the sum of the current leaving that point or junction.
Kirchhoff’s Voltage Law (KVL) - A law stating that the voltage supplied to a DC circuit must equal the sum of the voltage drops within the circuit.
KVL - Refer to Kirchhoff’s Voltage Law
L - Length of wire immersed in magnetic field, in meters.
Laser Diode - A semiconductor device which emits a laser beam.
Last Door Arming - A feature found on some security systems that enables the system to suspend itself from arming until the last door of the vehicle has been secured.
LCD - Refer to Liquid Crystal Display
Lces - The electrical inductive equivalent of Cms, in henries.
Le - This is the voice coil inductance measured in millihenries (mH). The industry standard is to measure inductance at 1,000 Hz. As frequencies get higher there will be a rise in impedance above Re. This is because the voice coil is acting as an inductor. Consequently, the impedance of a speaker is not a fixed resistance, but can be represented as a curve that changes as the input frequency changes. Maximum impedance (Zmax) occurs at Fs.
LED - Refer to Light Emitting Diode
Length - Typically in reference to a measurement of the longest part of a 3 dimensional object, used most commonly in custom subwoofer enclosures.
Levc - Driver voice coil inductance.
Lexan - A brand of acrylic plastic. Commonly used in optically clear and translucent colors for custom installation applications.
Light Emitting Diode (LED) - A form of diode that sheds light when connected in a forward biased condition. LED lighting is used in the many applications for status indicator purposes as well was an alternative to incandescent lighting.
Line Level - The standard preamplifier output level of a signal from an audio source other than a turntable. Usually between 100mV and 1V, but may be as high as 5V or more from some preamplifiers.
Linearity - In an audio device, the ability to accommodate the flow of the original source signal without distorting or altering it in any way. A component is linear if it accurately reproduces the source signal regardless of the signal's frequency.
Linearity Error - The deviation in response from an expected or theoretical straight line value for instruments and transducers (speakers).
Line-out Converter (LOC) - A device that converts high level stereo signal into low level (RCA) stereo signal in order to integrate and aftermarket amplifier.
Liquid Crystal Display (LCD) - A type of digital display made of a material that changes reflectance or transmittance when an electrical field is applied to it.
Load - The electrical demand of a process, expressed in current (amps), power (watts), or resistance (ohms).
Lobing - This refers to the radiation pattern of a combination of two or more loudspeaker drivers at a certain frequency(ies) that effects of lobing are of greatest concern, since this determines how well the speaker preserves the tonality of the original recorded content.
Local / Distance Switch - Changes the sensitivity of the tuner. When switched to local (LO), the stronger local stations are received with a higher image rejection. When switched to distance (DX), the weaker, distant stations are received but with less image rejection.
Long Term Evolution (LTE) - An air interface standard of high speed wireless data transmission used 4G wireless data communications. LTE is based on the GSM/EDGE and UTM/HPSA network technologies, although LTE is incompatible with 2G and 3G air interface networks so it must be operated in a separate wireless spectrum.
Lossless Music - Relating to data compression without loss of imformation. FLAC, Apple Lossless (ALAC) and WMA Lossless are examples of lossless compression music formats. For example, they compress a music CD to less than it’s original size, but the resulting file is nowhere near as small as MP3 and AAC.
Loudness - This control allows you to boost the lower frequencies in your music for full, rich sound at lower volumes.
Loudness Control - Intended to boost low frequencies at lower volume levels and should not be used at high volume listening levels.
Loudspeaker - An electro acoustic transducer which converts electrical audio signals at its input to audible waves at it's output. May also refer to a given driver of a multiple speaker system and not to the whole speaker system as might a speaker.
Loudspeaker Compliance - The acoustical and mechanical equivalent of capacitance. Determines how easily a speaker cone/ voice coil assembly will move when an electrical signal is applied to it.
Low Frequency - Refers to radio frequencies within the 30-3000 kHz band. In audio it is usually refers to frequencies in the 20-150 Hz band.
Low Frequency Driver - A loudspeaker specifically designed to reproduce long, low-frequency wave lengths. The driver typically has a large cone, magnet structure, and voice coil. Woofer.
Low Midrange - The range of audio frequencies between 250 Hz and 500 Hz that contains low order harmonics of most instruments and is generally viewed as the bass presence range. When as signal of 300Hz is boosted it adds clarity to the bass and lower-stringed instruments. Too mush boost around 500 Hz can cause a sound of muffle.
Low Pass Filter (LPF) - A network of elements used to attenuate all frequencies above a predetermined frequency. Frequencies below the cutoff point pass without any effect.
Lows - Term which refers to a set of speaker components used to reproduce frequencies below 500 Hz as in a set of woofers. May also refer to the low frequency drivers of a set of separates. Not treble.
Low Voltage Differential Signaling (LVDS) - A type of digital video interface format used in some automotive applications in which a digital video signal is transferred from one or more devices to a screen in the dash over twisted pairs of copper cables. Commonly used for navigation or rear view cameras in modern OE automotive applications.
L-Pad - An L-pad is a passive device which lets you control the output level of the speakers without changing the impedance seen by the amplifier. A constant impedance is not really necessary for the amplifier but if you are using passive crossovers, a constant impedance is necessary to prevent the crossovers frequency from changing.
LPF - Refer to Low Pass Filter
LTE - Refer to Long Term Evolution
LVDS - Refer to Low Voltage Differential Signaling
m - Refer to Milli
M - Refer to Mega
mA - Refer to Milliamps
Magnet - A device that can attract or repel pieces of iron or other magnetic material. Speaker magnets provide a stationary magnetic field so that when the coil produces magnetic energy, it is either repelled or attracted by the by the stationary magnet.
Magnetic Flux Density (B) -
Malfunction Indicator Light (MIL) - A dash mounted indicator of a re-occurring DTC in a vehicle with OBD-II. Also called the “Check Engine” light.
Mas - Acoustical equivalent to Mms.
Masking - Also referred to as auditory masking, occurs when the perception of one sound is affected by the presence of another sound. Masking in the frequency domain is known as simultaneous masking, frequency masking or spectral masking. Masking in the time domain is known as temporal masking or non-simultaneous masking.
Material Safety Data Sheet (MSDS) - The technical and safety information for any specific chemical(s) that OSHA requires a business to have on file in an accessible location.
Matrix Processing - A signal processing scheme in which standard 2 channel audio is processed with proprietary methods to derive a multi-channel output to achieve the effect of surround sound. Examples are Dolby Pro Logic IIx, Harman Logic 7, DTS NEO:6, etc.
Maximum Linear Excursion - Is defined as how far the cone of a speaker linearly travels from its resting position. In general lower frequency drivers or subwoofers are designed to move more air and have more excursion than those of higher frequency.
Maximum Power Rating - The maximum power rating is generally the maximum power threshold of any audio components output. Some manufacturers rate this measurement off of dynamic power or “perfect condition” burst power. This measurement is typically not the most accurate to go by when choosing audio components.
MDF - Refer to Medium Density Fiber Board
MECP - Refer to Mobile Electronics Certified Professional
Media Oriented Systems Transport (MOST) - A data transfer infotainment system, usually optical, engineered for the mobile environment in use on many modern OEM applications from 2002 and up.
Medium Density Fiber Board (MDF) - This is a wood made of many very small particles of wood which is compressed and heated, glued with a resin, and then cut to shape a full or partial sheet of wood. MDF is typically used to construct subwoofer enclosures and interior custom fabricated pieces.
Mega (M) - A prefix that means 106 (one million in the US). 1 MHz equals 1,000,000 Hertz.
Megahertz - 1,000,000 (1 million) cycles per second. Wireless mobile communications within North America generally occur in the 800 MHz, 900 MHz and 1900 MHz spectrum frequency bands.
Memory - The word most commonly used to refer to a system’s ability to retain specific information.
Metal Oxide Semiconductor Field Effect Transistor (MOSFET) - A type of field-effect transistor (FET). It has an insulated gate, whose voltage determines the conductivity of the device. This ability to change conductivity with the amount of applied voltage can be used for amplifying or switching electronic signals.
mH - Refer to Millihenries
MHz - Refer to Megahertz
Micro (µ) - A prefix that means 1/ 106 (one millionth in the US). 1 µV equals 1/1,000,000 of a volt.
Microfarads (mF) - A unit of capacitance, also represented with µF, equivalent to 0.000001 (10 to the -6th power) farad. The microfarad is a moderate unit of capacitance. In utility alternating-current (AC) and audio-frequency (AF) circuits, capacitors with values on the order of 1 mF or more are common.
Microprocessor - A semiconductor that can be programmed to perform a variety of tasks in many different electronic applications.
Midbass - High midrange or upper midrange cannot reach low, with a minimum range of about 60 Hz to 4 kHz. Midbass is typically dependent on the range capable of the midrange driver or subwoofer being used itself.
Midrange - The range of audio frequencies between 500 Hz and 2 kHz that when boosted, can increase prominent vocals in music. It can become very tinny or horn like if boosted too much in this range.
Midrange Driver - A loudspeaker specifically designed to reproduce the frequency in the middle of the audible bandwidth. Most musical energy lies in the midrange band. Midrange drivers are commonly seen to reach anywhere from 250 Hz to 2 kHz.
Midrange Frequency - This range is mostly dependent on the settings of the sound processing and the real world capability of the midrange driver or loudspeaker itself. Midrange can be produced anywhere from 250 Hz to 2 kHz.
MIL - Refer to Malfunction Indicator Light
Milli (m) - A prefix that means 1/ 103 (one thousandth). 1 mA equals 1/1,000 of an amp.
Milliamps (mA) - A unit of measurement of electrical current equal to 1/1000th of an ampere (0.001 amperes). The milliamps is the most common unit used when measuring quiescent (or “standby”) current draw.
Millihenries (mH) - A unit of inductance that is equal to one thousandth of a henry.
MIMO - Refer to Multiple Input, Multiple Output
MIN/MAX - A feature of a DMM in which the highest (MAX) or lowest (MIN) recorded value over the measurement period is displayed.
Mmd - Diaphragm mass, in grams.
Mms - The driver's effective mechanical mass (including air load), in kg. This parameter is the combination of the weight of the cone assembly plus the ‘driver radiation mass load’. The weight of the cone assembly is easy: it’s just the sum of the weight of the cone assembly components. The driver radiation mass load is the confusing part. In simple terminology, it is the weight of the air (the amount calculated in Vd) that the cone will have to push.
Mobile Electronics Certified Professional (MECP) - Is a certificate of achievement program in the United States that it is managed and administered by Consumer Electronics Association (CEA).
Mobile Telephone Switching Office (MTSO) - is the mobile equivalent to a PSTN Central Office. The MTSO contains the switching equipment or Mobile Switching Center (MSC) for routing mobile phone calls. Also contains the equipment for controlling the sites that are connected to the MSC.
Mobile Switching Center (MSC) - This is the centerpiece of network switching subsystem (NSS). The MSC is mostly associated with communications switching function, such as call setup, release, and routing.
Module - A term commonly used to describe a self-contained part or device that can perform a specific function.
Monaural - A sound recorded or reproduced in only one channel.
Monitor - With security this is a security system input that awaits a trigger or command from a sensor or vehicle electrical circuit. In auto video the video display device(s) used to view the video output generated by the video source. Typically an LCD screen in a mobile application.
Mono - Refer to Monaural
Motion Sensor - A sensor specifically designed to detect a gentle or sharp up and down or side-to-side motion of the vehicle.
MOSFET - Refer to Metal Oxide Semiconductor Field Effect Transistor
MOST - Refer to Media Oriented Systems Transport
Moving Picture Experts Group (MPEG) - A working group of authorities that was formed by ISO and IEC to set standards for audio and video compression and transmission.
MP3 (MPEG 1, Audio Layer 3) - A popular encoding and variable compression scheme for digital music. Must have a device with MP3 decoding for playback.
MPEG - Refer to Moving Picture Experts Group
Ms - The total moving mass of the loudspeaker cone.
MSC - Refer to Mobile Switching
MSDS - Refer to Material Safety Data Sheet
MTSO - Refer to Mobile Telephone Switching Office
Multimeter - A common term used to describe a VOM (voltage ohm meter). A multimeter usually has the ability to measure volts, resistance (ohms), and amperes or milliamperes.
Multi-path Interference - This is interference affects FM radio reception. FM waves travel in a straight line, so anything between you and the FM transmitter can cause multi-path interference. When FM signals bounce off buildings and other large objects, the tuner picks up the same signal more than once, at different times. This create "echoes" that confuse the tuner by mixing with the original signal.
Multiple Input, Multiple Output (MIMO) - The use of multiple antennas at both the transmitter and receiver to improve communication performance. It is one of several forms of smart antenna technology. Note that the terms input and output refer to the radio channel carrying the signal, not to the consumer devices having antennas.
Multiplex (MUX) - A low current, multi function circuit found on many newer vehicles used in variety of functions previously supported by dedicated wires for each discrete function. MUX circuits use variable voltages or data messages on a single wire (or pair of wires) between a controller and a receiving device (such as a BCM) to other conditions. The goal is weight and cost savings for vehicle manufacturing. These systems are often low voltage (less than battery voltage) depending on the function tested. Also called “Multiplex” or “Variable Voltage” circuits.
Multi-Source - An audio/video system featuring multiple source units.
Multi-Zone - An audio/video system with multiple locations to listen and view the A/V entertainment.
Music - 1. an art of sound in time that expresses ideas and emotions in significant forms through the elements of rhythm, melody, harmony, and color. 2. the tones or sounds employed, occurring in single line (melody) or multiple lines (harmony), and sounded or to be sounded by one or more voices or instruments, or both. 3. musical work or compositions for singing or playing. 4. the written or printed score of a musical composition. 5. such scores collectively 6. any sweet, pleasing, or harmonious sounds or sound: the music of the waves 7. appreciation of or responsiveness to musical sounds or harmonies: Music was in his very soul.
Mute - Silent, attenuate.
MUX - Refer to Multiplex
n0 - The reference efficiency of the system.
n - Refer to Nano
Nano (n) - A prefix meaning 10-9 or 0.000 000 001
National Transportation Safety Board (NTSB) - An independent agency charged with determining the portable cause of transportation accidents and promoting transportation safety.
National Television System Committee (NTSC) - An acronym used to describe the analog color television broadcast standard used in North America and Japan, though also a video transfer standard between compatible devices still in use today through the composite video connection on video devices.
Navigation Receiver - A typical in-dash navigation system consists of a car stereo with a built-in monitor (ranging from 6-1/2" to 7"), an external GPS antenna, and sometimes a hideaway connection box that contains the A/V inputs and outputs. The stereo mounts in the factory stereo slot in your dash. The hideaway box is usually mounted behind the dash or under a front seat. In addition to CD playback and AM/FM reception, most in-dash systems include DVD playback, so you can watch a movie on the built-in screen when the car is parked. Installation of an in-dash system can be complex, as they require connection to power, ground, the vehicle speed sensor, and the parking brake. If your car has a single-DIN or even an old-school shaft style receiver opening, you can always use a portable GPS navigation system.
Navigation System - is a GPS receiver and audio/video (AV) components, also referred to as PND or Route Guidance System, designed for a specific purpose such as a car-based or hand-held device or a smartphone app. The global positioning system (GPS) is a 24-satellite navigation system that uses multiple satellite signals to find a receiver's position on earth.
Negative Door Switches - A door switch circuit that provides the negative polarity trigger for the factory interior lights, key buzzer, factory alarm, BCM, etc.
Negative Lead - The lead or line connected to the negative terminal of a current, voltage, or power source.
Negative Polarity - A reference to the signal's position or voltage below the median line.
Network Switching Subsystem - This is the component of a GSM system that carries out call switching and mobility managements functions for mobile phones roaming on the network of base stations.
Newton (N) - A derived unit of force, named after Isaac Newton in recognition to his work mostly related to Newton’s Second Law of Motion. It is equal to the amount of net force required to accelerate a mass one kilogram at a rate of one meter per second squared.
Noise - 1 Unwanted sound of no specific frequency or amplitude. 2 Random sound of many frequencies not harmonically related (buzzing, hiss, pops, static, whine, etc.).
Nominal Impedance - The minimum impedance a loudspeaker presents to an amplifier, directly related to the power the speaker can extract from the amplifier.
Nominal Power - Measured in watts, it is best represented by RMS (root means square.) This figure tells us how much power the speaker can comfortably handle for a sustained period of time. Also referred to as continuous, or nominal power. Some speakers only list a peak power rating.
Normally Closed - Refers to the electrical state in which a switch may rest. Its contacts are held together or closed so that current is allowed to flow through its contacts.
Normally Open - Refers to the electrical state in which a switch may rest. Its contacts are held apart or open so that no current flows through its contacts.
NSS - Refer to Network Subsystem
NTSB - Refer to National Transportation Safety Board
NTSC - Refer to National Television System Committee
Nucleus - The positively charged center of an atom, made of protons and neutrons, around which electrons orbit.
OBD - Refer to On Board Diagnostics
OBD-II - Refer to Second Generation On Board Diagnostics
Object Exchange Profile (OBEX) - This is a profile, also known as Infra-red OBEX (IrOBEX), that facilitates the exchange of files between devices. Which allows Bluetooth exchange of what is typically Infra-red exchangeable content (such as contacts or calendar entries on a PDA type device).
Object Push Profile (OPP) - This profile must be "pushed" via Bluetooth to transfer content (such as address books, pictures, or other stored information) into other Bluetooth devices. The exchange must be initiated and accepted by the users, it is not just automatic whenever two Bluetooth devices are within range of one another.
Occupational Safety and Health Act (OSHA) - The United States governmental agency that establishes and enforces safety standards in the workplace.
Octave - A measured musical interval between two tones when the ratio between the frequencies of the tone is 2:1 (double or half of the other) “Oct” is a prefix meaning “eight”. In music, there are 8 steps, tones, or “notes” within an octave. For notes spaced an octave apart, human ear hears them as being essentially the same. That’s why, in music, notes spaced an octave apart have the same name; “A”, “B”, “C”, etc.
OE - Refer to Original Equipment
OEM - Refer to Original Equipment Manufacturer
OFC - Refer to Oxygen Free Copper
Off Axis - Veering away from the imaginary line (axis) directly in front of the receiving end of a microphone. Measured as degrees of an angle. (For example, a sound coming from directly behind the microphone is said to be 180 degrees off-axis.)
Ohm (W) - The unit of electric resistance and impedance. One ohm is the resistance value through which one volt will maintain a current of one ampere.
Ohm’s Law - Current in a circuit is directly proportional to the voltage, and inversely proportional to resistance. It also includes the relationships of watts to amps, volts and ohms.
Open Circuit - A circuit containing a switch, filament, voice coil, etc., which is not intact and current cannot current flow through.
Optical Input - A digital output that transmits pulses of light through an optically conductive cable from a compatible Optical Output
Optical Output - A digital output that transmits pulses of light through an optically conductive cable from a compatible Optical Input.
On Board Diagnostics (OBD) - Is an automotive term referring to a vehicle's self-diagnostic and reporting capability. OBD systems give the vehicle owner or repair technician access to the status of the various vehicle subsystems. The amount of diagnostic information available via OBD has varied widely since its introduction in the early 1980s versions of on-board vehicle computers. Also refer to OBD-II.
Order - Used to describe the quality, nature, or importance of something. In audio order is used to refer to the point of a crossover filter or the type of a subwoofer enclosure. In mathematics order is the degree of complexity of an equation, expression, etc., as denoted by an ordinal number. In distribution order is a request (something) to be made, supplied, or served.
Organic Vapor (OV) - Harmful vapors for inhalation. Typically filtered with charcoal respirator cartridges in an OSHA approved respirator mask.
Oscillator - A device that produces an alternating current or pulsating current or voltage electronically.
Oscilloscope - A measurement tool that can display a signal waveform while simultaneous measuring the featuring the frequency and voltage of the signal. Among other uses, this tool is very useful in setting up the gain position on amplifiers to avoid prematurely clipping the waveform coming out of the amplifier.
OSHA - Refer to Occupational Safety and Health Act
Out of Phase - Being or happening in (or out of) synchrony or harmony. In audio this refers to the wave of a speaker or subwoofer. The wave travel of the speaker is not in phase which can cause cancellation of other speakers. This can also mean that a speaker or subwoofers polarity is reversed, placing the speaker out of phase.
Output - In audio the high-level (speaker) or line-level (RCA) signals sent from one system component to another, or the high-level signal from an amplifier to the system speakers. In security any wire on a security system designed to produce a signal intended to be wired to some outside circuit or device. Siren wires, flashing light wires, and door locks are all outputs.
OV - Refer to Organic Vapor
Override Switch - A switch that provides a secondary means to disarm or override a security system in the event the primary means is unavailable. This switch is also often used for valet or other security programming functions. Refer to Emergency Override.
Oversampling - Doubling or quadrupling (or by even a higher factor of 2 squared) the sampling frequency during the digital to analog process to obtain a high frequency for digital filtering.
Oxygen Free Copper (OFC) - Oxygen-free high thermal conductivity (OFHC) copper is a group of wrought high conductivity copper alloys that have been electrolytically refined to reduce the level of oxygen to .001% or below. This is the most commonly used and most reliable type of wire in car audio, as opposed to Cooper Clad Aluminum (CCA).
p - Density of air at STP 1.18 kg/m^3.
P - Refer to Power or Peta
Pa - Refer to Acoustical Power
Pain Generator(s) - A name given to a type of siren that is specifically designed to produce a sound of the proper volume and pitch so as to cause physical pain to a thief's ears.
Pair - Also referred to as pairing, the term is used to describe wirelessly connecting two or more compatible Bluetooth devices to one another. Where numeric keypads are present on one (or both) devices, often a code is required for first time pairing. Once paired, the devices can operate with one another using their established Bluetooth profile(s).
PAL - Refer to Phase Alteration Line
Panic - The name given to the feature of a security system that provides the ability to the operator to cause the system’s siren to sound at will. The panic feature is typically initiated either by pressing a button or buttons on the remote control transmitter by keypad command, by push button, or by toggle switch.
Parallel - Lines, planes, surfaces, or objects, side by side and having the same distance continuously between them.
Parallel Wiring - A circuit in which two or more devices are connected to the same source of voltage, sharing a common positive and negative point, so that each device receives the full applied voltage.
Parallel/Series Wiring - A combination of parallel and series circuits wired together to produce a certain voltage or impedance. This is typically used in wiring subwoofers and speaker voice coils together or individually to offer more options of impedance.
Parametric - A type of equalizer with adjustable parameters such as center frequency and bandwidth (Q) as well as amplitude.
Parasitic Current Draw - A term that describes the amount of current consumed by a circuit when it is not performing any work or otherwise “at rest”. Also refer to Quiescent Current or Standby.
Pascal (PSI) - the SI unit of pressure, equal to one newton per square meter, approximately 0.000145 pounds per square inch, or 9.9 × 10-6 atmospheres.
Passive - A component that does not generate or control electrical current (as opposed to an “Active Device”). In audio applications, this usually refers to a piece of gear that does not include an amplifier as part of its design. For example, active speakers are self-powered, while passive speakers require an external amplifier in order to reproduce sound.
Passive Arming - The ability of some security systems to arm without requiring any direct action from the operator of the vehicle
Passive Radiator - a device that looks just like an ordinary driver, except it has no magnet or voice coil. A radiator is usually a highly compliant device, with a similar cone material and surround found on regular active drivers. The radiator must usually be at least as large (or larger) than the driver it is aligned with. The passive radiator is tuned to Fb and used in place of a port, providing bass reinforcement for the driver in a similar fashion as any regular ported box. A clear advantage of the radiator is the absence of port noise, and some audiophiles claim the radiator provides a better sounding bass than a ported enclosure. Disadvantages include difficulty in tuning, and the extra required baffle area for the radiator. Most radiators can be tuned with either weights or silicone, adding material in a balanced manner until Fb is attained.
Passive Crossover - uses inductors (coils) and capacitors to direct proper frequencies to appropriate drivers. These crossover systems can be simple (First Order = 1 component @ -6 dB/octave slope) to complex (Fourth Order = 4 components @ -24 dB/octave slope).
PDA - Refer to Portable Navigation Device
Pe - Term referring to electrical power
Peta (P) - A prefix meaning 1015 or 1,000,000,000,000,000
Peak Power - Peak power is measured during a brief musical burst, such as a sudden drum accent. Some manufacturers display peak power ratings on the face of their products. The RMS power rating is more significant, and we recommend using it for comparison purposes.
Phase - The relative position of two sound waves with respect to each other.
Phase Alteration Line - This describes the color television broadcast standard used in many Western European countries (except France), the Middle East, and parts of Africa and South America.
Phase Shift - Frequency interaction in the crossover region of passive crossovers which can cause some frequencies to be delayed with respect to other frequencies.
Photo Detector (photo diode) - A semiconductor device which provides variations in current as a function of light intensity.
Phone Book Access Profile (PBAP) - This profile makes information from the mobile’s phone book available in the hands-free car kit and is part of the enhancements to the Hands-Free Profile (HFP 1.5V or higher). This includes common features from the mobile phone such as enhanced call control, phone status indicators, response and hold, and information about the subscriber number linked via the phone’s address book. Audio quality is also enhanced over HP (talk and listen only) profile, which is a viable selling point for more premium kits and where an installer must consider microphone placement and how the audio will be heard from the caller (through existing speakers or via separate, stand alone speakers).
Piezo Electric Tweeter - A very efficient, highly directional tweeter which operates without a crossover or magnet. Driver creates sound when a quartz crystal receives electrical energy.
Pink Noise - Sound with all frequencies perceptible to the human ear reduced to an equal energy level.
Pink Noise Generator - A device used to generate pink noise that usually includes a calibrated microphone.
Pinswitch - A simple spring-loaded mechanical switch used in many different vehicles designed to turn on interior lights when doors are opened. Pinswitches are also used in the installation of most security systems in the hood or trunk/hatch as a means of triggering the system should these points be opened
Pit - One of the depressions that represents data in a compact disc. May also be referred to as bumps, this is what the pick up sees.
Plate Speaker - A speaker that has two drivers mounted side by side on a flat surface.
Plexiglas - a solid transparent plastic made of polymethyl methacrylate (the same material as perspex or Lucite).
PND - Refer to Portable Navigation Device
Polarity - A very simple concept. Any electrical signal has polarity, and it is a reference to the signal's position or voltage above or below the median line. A device which inverts the polarity of a signal will simply swap positive voltage to negative voltage and vice versa
Pole Mount - A common automotive speaker design with the high frequency driver mounted on a center pole. Newer designs mount the high frequency driver in the same location above the lower frequency driver with a bridge. This prevents problems such as dust and dirt from entering at the base of the pole.
Polyfill (Poly-fil) - is typically nondirectional weaved padding made from polypropylene fibers that maybe used inside loudspeaker enclosures to cushion the back wave. This provided cushion to the back wave tricks the subwoofer into operating as if the enclosure has more inner air volume than it truly offers. Polyfill is ideal in applications when there is not enough space for a needed larger enclosure or when the enclosure used simply does not offer the inner air volume needed for the sub to operate efficiently.
Polypropylene - Also known as polypropene is a thermoplastic polymer used in a wide variety of applications. In the Car Audio world its main uses are in speaker and subwoofer diaphragms, electrical tape, and also as fibers in the case of Poly-fil. It is typically manufactured using the injection molding technique.
Positive Polarity - A reference to the signal's position or voltage above the median line.
Portable Navigation Device (PND) - Also referred to as a Personal Navigation Device or Personal Navigation Assistant, is a portable electronic product which combines a positioning capability (such as GPS) and navigation functions. Some PNA devices are PDAs with limited features and can be unlocked.
Ported Enclosure - A type of speaker enclosure that uses a duct or port to improve efficiency at low frequencies. Excellent design for lower power systems, as the port often adds up to +3 dB to low frequency efficiency. F3 can be set considerably lower with proper design, although low frequency roll-off is generally -24 dB/octave. Good transient response with proper tuning, although the driver loses damping below the tuning frequency. Excellent power handling about Fb, but source material or frequencies below Fb cause the driver to progressively perform as if it were not enclosed at all. Due to this, ported enclosures without a low frequency filter may have lower power handling compared to other designs. More difficult to properly build and tune than a sealed enclosure, with several "optimum" alignments available depending upon the Qts of the driver.
Potentiometer - Often thought of as a fancy word for “knob,” a potentiometer is basically any mechanism that controls input or output voltage by varying amounts (for example, panning a signal left/right, volume control, or the amount of signal sent to an aux send or bus. Potentiometers can be knobs or faders, meaning that almost every control on a console that isn’t a button or switch is a potentiometer. However, many engineers commonly refer to faders as “faders” and knobs as “pots.”
Power (P) - The time rate at which work is done or the rate at which energy is used. Basic equations for Electrical Power are: P = V^2/R or P = I^2*R.
Power Cell - A single unit for producing DC electricity by electromechanical or biochemical action. A common 12.66V vehicle battery is composed of a number of individual cells connected together. Each cell is typically rated at 2.11 volts; a common automotive battery is composed of six separate two-volt sells.
Power Handling - Total system power refers to the total power consumption of the unit, rather than the power handling of the speakers or the power output of the amplifier. ... In some cases, an audio device may be measured by the total system power of all its loudspeakers by adding all their peak power ratings.
Power Line Noise - A varying AC ripple that is found riding on a DC voltage. It is recognized by a whining that varies with engine speed.
Power Windows - The feature where the opening and closing of the vehicle’s windows is performed by some mechanical means other than human power. Power windows are typically operated by electric motors.
Power Supply Capacitor - A polarized, large value capacitor specifically intended to stabilize supply voltage during periods of peak current demand. Also called a “Stiffening Capacitor”.
Pre-amp Fader - A circuit that allows effective level control of two amplifiers, built in and external without loss of power.
Preampilfier (Preamp) - A low-noise amplifier designed to take a low-level signal (for example, from a microphone) and bring it up to normal line level before sending it into the mixing console.
Presence Frequencies - The range of audio frequencies between 4 kHz and 6 kHz that when boosted, can increase the sense of presence, especially on voices.
Preset - A factory programmed set of parameters on a synth, signal processor, plug-in or other electronic device.
Professionalism - The competence or skill expected of a professional.
Protons - These make up part of the nucleus of a ll atoms except hydrogen, whose nucleus consists of a single proton. In neutral atoms, the number of protons is the same as the number of electrons. In positively charged atoms (as in electricity conductive materials), the number of protons is greater than the electrons outnumber protons.
Proximity Sensor - A common term for a spatial-type sensor that can be either the radar, or infrared type. Also refer to Spatial Sensor.
PSI - Refer to Pascal or Pound per Square Inch
Pulsed Output - An output of a security system usually used to flash parking lights or honk horns; it is pulsed or turned on and off by the security system. In some cases an output may be programmable to behave this way when activated.
Pulse Width Modulation (PWM) - A fancy term for describing a type of digital signal. Pules width modulation is used in a variety of applications including sophisticated control circuitry.
Push-Pull Configuration - Refer to Isobaraic
PWM - Refer to Pulse Width Modulation
Q - Ratio of reactance to resistance (series circuit), or resistance to reactance (parallel circuit).
Qa - The system’s Q at Fb, due to absorption losses.
Qec - The system’s Q at resonance (Fc), due to electrical losses.
Qes - The drivers Q at resonance (Fs), due to electrical losses.
Ql - The system’s Q at Fb, due to leakage losses.
Qmc - The system’s Q at resonance (Fc) does to mechanical losses.
Qms - The driver’s Q at resonance (Fs), due to mechanical losses.
Qp - The system’s Q at Fb, due to port losses (turbulence, viscosity, etc.).
Qtc - Measurement of a speaker and enclosure working together as one.
Qts - The measurement of the speaker as a motor, taking into consideration all mechanical and electrical losses.
Quad Voice Coil (QVC) - A subwoofer that has four separate voice coils. The subwoofer or driver itself having 4 positive leads and 4 negative leads. This amount of voice coils make wiring many different loads to possible.
Quiescent Current - The term given to describe the amount of current consumed by a circuit when it is not performing any work (sometimes referred to as standby current). Battery life is determined by the total current drain composed of quiescent current and load current.
Radar Sensor - A common name for a type of spatial sensor used in automotive security system’s to protect/monitor open areas (such as convertibles, truck beds, etc.).
Radio Data System (RDS) - RDS scrolls text on the head unit display to help sort broadcast by type (talk ,sports, etc.) and provide drive-time warnings of accidents.
Range - In audio this is usually described as frequency range, this is a system’s frequency response, beyond which the frequency is attenuated below a specified tolerance. Also, the frequency band within which a receiver or component is designed to operate. In security the term used to quantify the maximum operating distance that can exist between a vehicle and the remote control transmitter. Range is usually expressed in feet or yards.
Rarefaction - A state or region of minimum pressure in a medium traversed by compression waves (sound waves).
Ras - Acoustical equivalent to RMS.
RDS - Refer to Radio Data System
RCA - Radio Corporation of America
RCA Connector - A plug and socket for a coaxial cable. They are found on all old audio/video devices and many new ones that continue to support analog signals. They are also used for digital signals.
Re - Refer to Resistance
Reactants - Something that takes part in and undergoes change during a reaction.
Real-Time Analyzer (RTA) - A spectrum analyzer that measures the amplitude versus frequency (X vs. Y plot) of an audio signal while in real time.
Rear Fill - A term used typically when referring the rear speakers or music audibly heard from the rear. This music is usually a bit less aggressive and not as easily heard as the front stage.
Receiver - A device designed to receive a signal or command from a source such as a transmitter.
Receiver (Rx) - A receiver mostly refers to that part of a device that receives signals; often, the device acts as both a transmitter and a receiver (transceiver) such as in the case of cell phones (cellular radio) and antennas used for data communication.
Recone - This term refers to replacement part(s) or sometimes a kit, that is necessary to repair a blown or damage subwoofer.
Rectification - The process of turning AC into (pulsing) DC. Modern alternators use a process called Full Wave Rectification with minimum of 6 diodes.
Red/Blue/Green RGB - This refers to an analog video signal transfer where the primary colors of red, green and blue each have their own conductor. RGB signals in automotive applications have three different variations: RGBS, RGBHV, and RgsB. The main differences are how the conductor that controls picture information synchronizing is implemented.
Relay - The most commonly used relay in the world of car audio and security is the Single Pull Double Throw (SPDT) relay.
Relay Isolator - An electrical device that divides direct current (DC) into multiple branches and only allows current in one direction in each branch.
Remote - A common name for the remote control unit transmitter used with a remote security system.
Remote Turn-On - The discrete turn-on circuit in most mobile electronic audio products. After market headunits typically have a remote turn-on output whereas preamp level processors and amplifiers typically have remote turn-on input.
Res - The electrical resistive equivalent of RMS.
Reset - The ability of a security system to automatically stop sounding the siren and return to an armed state after being triggered, as long as no further trigger conditions are present.
Resistance (Re) - Driver DC resistance, mainly voice coil impedance at rest.
Resistor - A device having a designed resistance to the passage of an electrical current.
Resonant Frequency (Fs) - The frequency of resonance in a given driver when in free air. This can be typically related to the optimal frequency in which to tune the driver to, or around.
Reverb Time -60dB (RT-60) -
Revolutions Per Minute (RPM) - Refers to a vehicle’s engine revolutions.
Rg - Amplifier source resistance (includes leads, crossovers, etc.).
RGB - Refer to Red/Blue/Green
Ripple - In acoustical response this is the deviation from a flat response in the pass band, generally used to describe vented subwoofer enclosure characteristics. With the charging system this is the amount of Alternating Current (AC) present on a DC circuit’s power line.
RMS - Refer to Root Mean Square
Root Mean Square (RMS) - Literally "root mean square." A DC voltage that will produce the same heating effect (power output in Watts) as the AC voltage. For a sine wave, the RMS value is equal to 0.707 times the peak value of an AC voltage. Example: divide Peak-to-Peak by 2 (or in half) and multiple by 0.707 = RMS voltage.
Roll-Off - Relating to the attenuation of frequencies, above or below a given point, at a specific rate.
Roll-Off Frequency - The steepness of a transmission function with frequency, particularly in electrical networks analysis, and most especially in connection with filter circuits in transition between a passband and a stopband. Roll-Off Frequency is the point in which this happens.
Roof Mount Antenna - A permanently-installed antenna located on the vehicle’s roof. Communication antennas are commonly roof mount applications (except for convertibles).
Route Guidance System - A GPS based, electronic guidance system installed into vehicles using digital mapping and point of interest information to facilitate getting from a location to the desired destination with precise directions. This is generally an installed item whereas a handheld (portable) navigation system is often called a PND.
RPM - Refer to Rotations Per Minute
RT-60 - Refer to Reverb Time -60dB
RTA - Refer to Real-Time Analyzer
Rx - Refer to Receiver (Rx)
SAF - Refer to Spouse Acceptance Factor
Scanning - The popular term given to the way a thief breaks into a remote security system by quickly and sequentially transmitting all the possible coeds of a victim’s security system.
SD - This is the actual surface area of the cone, normally given in square cm.
Sealed Enclosure - A sealed enclosure refers to an alignment of subwoofer enclosure that has no inward or outward flow of air, essentially air tight. Sealed from outside atmosphere or environment.
Second Generation On Board Diagnostics (OBD-II) - Present on all vehicles sold in the US since 1996. is an automotive term referring to a vehicle's self-diagnostic and reporting capability. OBD systems give the vehicle owner or repair technician access to the status of the various vehicle subsystems. The amount of diagnostic information available via OBD has varied widely since its introduction in the early 1980s versions of on-board vehicle computers. Early versions of OBD would simply illuminate a malfunction indicator light or "idiot light" if a problem was detected but would not provide any information as to the nature of the problem. Modern OBD implementations use a standardized digital communications port to provide real-time data in addition to a standardized series of diagnostic trouble codes, or DTCs, which allow one to rapidly identify and remedy malfunctions within the vehicle.
Seat Sensor - A pressure -activated switch designed specifically for use in detecting any pressure applied to vehicle’s seat.
SECAM - Refer to System Electronique Couleur Avec Memoire
Sensitivity - In audio this is the rating loudspeaker that indicate the level of sound intensity the speakers produces (in dB) at a distance of one meter when it receives one watt of input. In security this is the relative adjustment of a particular sensor with regard to how easy or difficult it is to trigger by its intended purpose. Very often the cause of unintended “false alarms” is due to overly sensitive security sensors that react to wind, loud noises, or otherwise normal circumstances.
Sensor - A device designed to detect or sense an intrusion or attack upon a vehicle by monitoring such things as motion, vibration, impact, sound or the presence of a foreign mass.
Sensor Bypass - The ability of a security system to automatically or manually delete or bypass the trigger from all or some of the sensors tied into the security system.
Serial Port Profile (SPP) – This profile defines the basic requirements for Bluetooth devices necessary for setting up connections using wireless communication over Bluetooth in lieu of a cable connection (such as USB) between two compatible devices. In mobile electronics, this is typically concerned with mobile phones, either for the hands-free communication in a “car kit” or (if equipped) access to the SIM card inside the phone. It’s also used in communication with serial data on products not necessarily associated with a phone such as in some signal processors and BT hands-free control units that need firmware updates from time to time.
Series - A closed circuit in which the current follows one path, as opposed to a parallel circuit, the current is divided into two or more paths. In a series circuit, the current through each load is the same and the total voltage across the circuit is the sum of the voltages across each load. For example, when it comes to a Dual Voice Coil (DVC) subwoofer, series wiring is from a positive terminal of one Voice Coil (VC) to the positive of the amp terminal. The remaining negative terminal of the same VC then wired to the positive terminal of the second VC, from there the negative terminal of the second VC is then run to the negative terminal of the amplifier completing the circuit.
Series/Parallel - A combination of parallel and series circuits wired together to produce a certain voltage or impedance. This is typically used in wiring subwoofers and speaker voice coils together or individually to offer more options of impedance. This is most commonly used when wiring together multiple speakers.
Service - A system supplying a public need such as transport, communications, or utilities such as electricity and water.
Sd - Effective piston radiating (surface) area of driver.
Shelving - While high and low pass filters are useful for removing unwanted signal above or below a set frequency, shelving filters can be used to reduce or increase signals above or below a set frequency.
Shock Sensor - A sensor that is a specifically designed to detect a shock or impact applied to the vehicle.
Short Circuit - The condition that occurs when a circuit path is created between the positive and negative poles of a battery, power supply, or circuit. A short circuit will bypass any resistance in a circuit and cause it not to operate.
Signal-to-Noise Ratio (S/N) - The S/N ratio indicates how much audio signal there is in the relation to noise, or a specific noise filter.
Sine Wave - A curve representing periodic oscillations of constant amplitude as given by a sine function. Also referred to “Sine Curve”.
Single DIN - A standard automobile radio body size. A Single DIN radio measures 2” X 7” and a Double DIN measures 4” X 7”. When factory radio/CD players are replaced with aftermarket units, the DIN standard ensures compatibility. However, some new dashboard trims or bezels may be require alteration. Also refer to DIN and Deutsche Industrie Normen.
Single Ended - Referring to audio input or output, this is an audio signal transfer scheme in which the outer shield of the 2 conductor cable is electrically common with BOTH left and right channels and only the center conductors differ in signal content. Most RCA input and outputs on mobile electronic equipment are single ended type.
Single Pole Double Throw (SPDT) - A switch or relay that has a common terminal with a switch that throws between Normally Closed (N/C) at rest and Normally Open (N/O) when energized.
Single Pull Single Throw (SPST) - A switch or relay that has only one pole or contact and can only throw or make electrical contact with one stationary contact.
Single Reflex Bandpass Enclosure - Also referred to as 4th Order, this refers to an enclosure which the speaker is mounted in a sealed chamber and fires into a ported chamber. By altering the size of the chambers, and the area and length of the port, you can alter its performance. The sealed section will determine the low frequency limit of the system while the ported side determines the amount of gain or loss and the shape of the response. The port needs to be tuned to the resonant frequency of the sealed enclosure to ensure a centered (symmetric) response shape.
Single Voice Coil (SVC) - A single coil, as opposed to multiple, on the speaker or subwoofer that allows to be directly wired up to a power source. This configuration typically offers 1 positive lead and 1 negative lead to wire into the given application.
Siren - Any kind of device, mechanical or electronic, that is designed to produce a loud warning sound when triggered by a security system.
SI Unit - Refer to Systeme International d’Unites
Skin Effect - The tendency of a high-frequency alternating current to flow through only the outer layer of a conductor.
SKU - Refer to Stock Keeping Unit
Slope - This term describes the rate which the audio level increases/decreases. Also refer to Roll-Off.
S/N - Refer to Signal-to-Noise Ratio
Solenoid - A cylindrical coil of wire acting as a magnet when carrying electric current.
Sound - A type of physical kinetic energy called acoustical energy. Also refer to Acoustical Energy.
Sound Discriminator - A device designed to listen to, evaluate, and discriminate between the sounds that may be hard within the interior of the vehicle, and then trigger the security system if the sound fits within the parameters of what the sensor is designate to react to. A glass break sensor is a common use of a sound discriminator.
Sound Masking - Is the addition of sound created by special digital generators and distributed by normally unseen speakers through an area to reduce distraction or provide confidentiality.
Sound Pressure Level (SPL) - A ratio of the absolute, sound pressure and a reference level (usually the Threshold of Hearing, or the lowest intensity sound that can be heard by most people). SPL is measured in decibels (dB), because of the incredibly broad range of the intensities we can hear.
Soundstage - Also called imaging, this refers to the composition the audio components and the frequency tuning of the stage in its entirety.
Sound Waves - Fluctuating waves of pressure that travel through a physical medium such as air. An acoustic wave consists of a traveling vibration of alternate compressions and rarefactions, whereby sound is transmitted through the air or other media.
Source Unit - Also known as a Head Unit, Deck, or Mobile Radio, the unit in which the audio (or video) program material originates. Source units may feature playback of multiple source material formats. The most common form of source unit is the in-dash head unit.
Spatial Sensors - Devices specifically designed to detect intrusions into or around the vehicle by monitoring the space in and around the vehicle for intruders. These senors work on a variety of different principles, including ultrasonic, radar, radio frequency, and infrared.
SPP - Refer to Serial Port Profile
SPDT - Refer to Single Pole Double Throw
SPST - Refer to Single Pole Single Throw
Speaker - A device that converts analog audio signals into the equivalent air vibrations in order to make audible sound.
Spider - A flat, round, springy device that holds the vibrating cone of a dynamic loudspeaker. The spider is where the diaphragm meets the voice coil.
Spike Suppression - The process of using a diode across the coil terminals of an electromechanical relay to suppress or “quench” any back EMF generated by the current exiting the magnet field of the coil.
SPL - Refer to Sound Pressure Level
Stereo - This can pertain to the entire make up of the vehicle stereo system (source unit, speakers, amplifiers, subwoofers, etc.) or it can simply refer to the source unit itself.
Staggered Tune - This refers to a technique used in the design of multi-stage tuned amplifiers whereby each stage is turned to a slightly different frequency.
Staging - The accuracy with which an audio system conveys audible information about the size, shape, and acoustical characteristics of the original recording space and the placement of the artists within it.
Standby Current Draw - Referred to as quiescent current, standby power, vampire power, vampire draw, phantom load, ghost load or leaking electricity (“phantom load” and “leaking electricity” are defined technical terms with other meanings, adopted for this different purpose), refers to the way electric power is consumed by electronic and electrical appliances while they are switched off (but are designed to draw some power) or in a standby mode.
Standby Mode - The state of an electrical device laying dormant or sleeping while still using a slight bit of power.
Starter Disable - Any circuit or device used alone or in conjunction with a security system that is designed to prevent the vehicle’s starter from operating.
Status -The state a system is in at any given time, typically used in security system and remote starter descriptions.
Stock Keeping Unit (SKU) - This refers to each single item carried by a retailer. Every color, style and item having its own vendor or vendee number has its own SKU.
Stiffening Capacitor - The unofficial name given to a polarized, large value capacitor specifically intended to stabilze supply voltage during periods of peak current demand. This term was coined by industry technical experts Richard Clark and David Navone. Also referred to as Power Supply Capacitor.
Sub Bass - The range of audio frequencies between 20 Hz and 60 Hz that when boosted, can increase the sense of power, the deep bass produced in this range is usually felt more than it is heard.
Sub-stage - The term "sub-stage" in mobile electronics is typically referring to the portion of the audio system that contains the subwoofer and subwoofer amplifier providing the low end bass.
Sub-sonic Filter - Also known as the Infrasonic Filter, cuts out the audible low range frequencies that can harm a driver. The filter helps to keep the driver from dipping into lower frequencies that the source unit may emit and can cause the subwoofer to fail if it is not capable of playing such low frequencies.
Subwoofer - A loudspeaker made specifically to reproduce frequencies below 125 Hz.
Subwoofer Enclosure - A specific enclosure designed for the optimal performance of a particular subwoofer, enclosing the back wave and using said wave to achieve ideal transient response. Enclosure alignments vary, due to specific subwoofer mechanical and thermal limitations typically listed in the T/S Parameters.
Subwoofer Unload - This is the process when a subwoofer completely unloads its potential output under certain enclosure compression scenarios. Typically seen when an enclosure is built and tuned to the improper specifications in accordance to the subwoofers parameters. Once the signal sends the driver into these sub optimal zones of frequency the driver will meet its mechanical limits, sometimes on even half the power it would take in an optimal situation.
Superconductor - A substance that is capable of becoming superconducting at sufficiently low temperatures. Superconductivity is a phenomenon of exactly zero electrical resistance and expulsion of magnetic flux field occurring in certain materials.
Surround - A surround is the soft material on a subwoofer that connects the basket to the cone or main diaphragm. Typically seen made from a foam, rubber or butyl composite.
SVC - Refer to Single Voice Coil
Switch - Any form of mechanical, electrical, electromechanical, magnetic, or mercury device that either opens or closes a circuit.
Switch Sensing - This refers to the inputs on a security system designed to detect a switch closure from such triggers as a door, hood, or trunk/hatch pin switches.
Systeme International d’Unites (SI Unit) - A complete metric system of units of measurement for scientists; fundamental quantities are length (meter), mass (kilogram), time (second), electric current (ampere), temperature (kelvin), amount of matter (mole) and luminous intensity (candela); The United States is the only country in the world not totally committed to using only SI Units.
System Electronique Couleur Avec Memoire (SECAM) - A term used to describe the color television broadcast standards used in France, Russia, and parts of Africa and Eastern Europe with French influence.
System Reset -Refer to Reset or Alarm Reset
Tach Wire - The term refers to an input commonly present on a vehicle remote starter system that allows the remote starter to monitor the engine speed and shut the vehicle down when a predetermined threshold is exceeded.
TDMA - Refer to Time Division Multiple Access
Terminal - A connector that attaches to the tip of a wire for connection purposes, or a spot on an audio device made to secure a wire that needs to disperse power or signal.
Tesla (SI) - The unit of magnetic flux density.
Thiele Small Parameters (T/S) - Sometimes referred to as TSP, are a set of electromechanical parameters that define the specified frequency of the loudspeaker driver.
THD - Refer to Total Harmonic Distortion
Thermal - The property of temperature considered in the performance characteristics of a device.
Thermal Energy - The process of energy converted in to heat, typically meaning the use of heat to produce energy.
Three-way - This refers to a three way speaker or three way channel setup. The three way speaker produces sound from three different devices called the midrange, woofer and tweeter drivers, each of which has its greatest efficiency in a specific range of frequencies.
Throttle Position Sensor - A sensor used to monitor the throttle position of a vehicle. The sensor is usually located on the butterfly spindle/shaft so that it can directly monitor the position of the throttle.
Time Division Multiple Access (TDMA) - A digital communications scheme used in some air interface technologies by dividing calls into time slots, each lasting only a fraction of a second. Each call is assigned a specific portion of time on a designated channel. By dividing each call into timed “packets,” a single channel can carry many calls at once. GSM is based on TDMA technology.
Tolerance Rating - The rating (expressed as percentage) given to an electronic component’s measured value compared against its rated value. Greater tolerance numbers indicate the measured value may be further away from the rated value.
TosLink - A proprietary connector style developed by Toshiba used in optical connections on consumer digital audio products.
Total Harmonic Distortion (THD) - Given as a percentage, a measurement of how much a device may distort a signal. Figures below 0.1% are considered to be inaudible with test tones. Frigures below 1% are actually very difficult to hear with music program material, hence the standard THD testing level of power amplifiers at 1%.
TPS - Refer to Throttle Position Sensor
Transducer - Any device that converts energy from one form to another, e.g., electrical to acoustic or vice versa. Loudspeakers and microphones are two types of transducers.
Transfer Function - The change in the low end of a low frequency system brought on by loading the device into the cabin of a vehicle.
Transformer - An apparatus for reducing or increasing the voltage of an alternating current.
Transient Response - The response of a system to a change from and equilibrium or a steady state. The transient response is not necessarily tied to abrupt events but to any event that affects the equilibrium of the system.
Transistor - Is a semiconductor device used to switch and amplify an electronic signal and power. There are many different types of transistors used for a wide variety of applications in different manners. The most popular in the car audio world would be the bipolar junction transistor (BJT) and field effect transistors (FET), which are similar in power dissipation and packages.
Transmission Line Enclosure - Also referred to a Quarter Wave Design, a transmission line redirects the standing waves away from the rear surface of the driver reducing the chance of standing waves interfering with the primary waves.
Transmitter - In security this is the name given to hand-held remote control unit used by a vehicle operator to arm/disarm and perform accessory functions on a vehicle security system. More commonly called a remote. In subscriber or radio services, this refers to a land based tower or device that transmits signals to compatible devices that are intended to receive those signals such as mobile phones, GPS navigation systems receiving real time traffic data over an RF network, satellite radio repeaters, and non-subscriber AM/FM radio.
Transmitter (Tx) - A transmitter is a circuit that accepts signals or data in and translates them into a form that can be transmitted, usually over a distance. The symbol for transmitter is either Tx or xmitter. A smaller variable inductor between the transmitter and the antenna feedthrough is used for fine tuning.
Transponder Key - A proprietary (electronically coded) key used in an OEM anti-theft system. The transponder key must correctly “communicate” the appropriate code to allow the vehicle to start and run normally.
Treble - Treble refers to tones whose frequency or range is at the higher end of human hearing. In music this corresponds to "high notes". The treble clef is often used to notate such notes.
Triaxial Driver - This is another term for “3-Way Speaker.” Refer to 3-way.
Trigger - The common name for any type of stimulus that will cause a security system to produce an alarm. A trigger could come from a pin switch, a sensor, or a direct command from a transmitter or accessory button.
Troubleshooting - The process by which problems are identified and repaired by process of elimination.
Trunk Release - A feature that enables the release of the trunk/hatch by remote control.
Tuner Selectivity - The ability of an AM/FM tuner to discriminate between two signals very close to each other in frequency. This is important in major metropolitan areas. Lower numbers are more preferable.
Tuner Stereo Separation - The ability of an FM tuner to accurately separate the left and right channel information of a stereo broadcast. Measured in decibels (dB), higher numbers are more preferable.
Tweeter - A loudspeaker designed to reproduce high frequencies. This covers anything from midrange to brilliance on the spectrum of sound.
Two-way - A 2 way speaker is a loudspeaker system with n separate frequency bands is described as "n-way speakers": a two-way system will have a woofer and a tweeter; a three-way system employs a woofer, a mid-range, and a tweeter.
Tx - Refer to Transmitter
Ultra High Frequency - This refers to frequencies between 300 and 3000 MHz, which used to include analog TV channels 14-69.
Un-fused Wire - Any section of wire between the power supply and a load that does not include the protection of a fuse or circuit breaker.
Uni-Body Chassis - A vehicle chassis design where the frame and main body cavity are integrated into a single structure.
Universal Product Code (UPC) - Also known as “bar code.” Numbers printed on product package that can be electronically scanned for information such as brand, manufacturer and price.
Upper Midrange - The range of audio frequencies between 2 kHz and 4 kHz that when boosted, can increase the sense of presence while responsible for the attack on percussive and rhythm instruments. If boosted too much around the 3 kHz range it can cause listening fatigue.
Unit - a quantity chosen as a standard in terms of which other quantities may be expressed.
UV - Refer to Ultra Violet
Vab - The volume of air having the same acoustic compliance as the enclosures.
Valence Electron - A negatively charged electron in the outer shell of an atom which can combine with other atoms to form molecules and electrical current flow. It is when negatively charged valence electrons leave conductive material atoms that they become “free electrons” and are attracted to the opposite polarity creating current flow.
Valet - A term used to describe the state in which a security system may be placed so that it would be prevented from arming passively and/or actively.
Valet Switch - The switch designed to provide the control to place the security system into or bring the system out of the valet state.
Variable Voltage Circuit - Refer to MUX
Vas - Also known as compliance, Vas is specified as the relative stiffness of a speaker suspension.
Vb - Net internal volume of an enclosure.
Vd - Maximum linear volume of displacement of the driver (this is the product of Sd multiplied by Xmax).
VDP - Refer to Video Distribution Profile
Vehicle Speed Sensor (VSS) - A discrete sensor on the vehicle that reports vehicle speed to the vehicle’s computer(s) and other speed dependent devices.
Vented Enclosure - Also known as Ported.
Very High Frequency (VHF) - This refers to frequencies between 30 and 300 MHz, which used to include analog TV channels 2-13.
Vf -The front volume of the bandpass enclosure.
VHF - Refer to Very High Frequency
Video Distribution Profile (VDP) – This profile allows the transport of video stream. The limitations for an in-vehicle application, which includes VDP, is that while transmitting/receiving video other supported Bluetooth profiles would not be available.
Voice Coil - A coil of wire that takes in the electrical energy coming from the amplifier and converts it into acoustic energy or mechanical motion.
Volt (E, V) - The term used to refer to the property of electrical pressure through a circuit.
Voltage - The electrical pressure required to do electrical work. Voltage is also caked potential. Voltage must be present for electrical current to flow within a closed circuit.
Voltage Drop - The amount of energy consumed when a dveice has resistance in its circuit. The voltage (E) measured across a resistance ® carrying a current (I). E= I x R.
Voltage Readout - A voltmeter, also known as a voltage meter, is an instrument used for measuring the potential difference, or voltage, between two points in an electrical or electronic circuit. Some voltmeters are intended for use in direct current (DC) circuits; others are designed for alternating current (AC) circuits.
Voltage Sensing - A name given o a form of alarm system trigger or remote starter input that relies on sensing a change in the voltage of the vehicle. Some remote starter systems rely on voltage sensing as an alternative to a tachometer input, for example.
Volume - The amount of space that a substance or object occupies, or that is enclosed within a container, especially when great. This can also mean the fluctuation of of the level of sound via a knob or buttons on a stereo.
Vr - The rear volume of a bandpass enclosure.
VSS - Refer to Variable Speed Sensor
W - Refer to Ohm
WAAS - Refer to Wide Area Augmentation
Watt - A derived unit of power, named after the Scottish engineer James Watt. The unit defined as one joule per second, measures the rate of energy conversion or transfer. For example, a medium-sized passenger automobile engine is rated at 50 to 150 kilowatts, while cruising it will typically yield half that amount.
Wattage - A term used to refer to Electrical Power.
Watt’s Law - Similar to Ohm’s Law, it demonstrates the relationship between Voltage (E) and Current (I) to represent a quantity of Power (P). With the Watt’s Law formula, knowing two elements can mathematically compute the third element.
Wave - A single oscillation in matter (e.g., a sound wave). Waves move outward from point of disturbance, propagate through a medium, and grow weaker as they travel farther. Wave motion is associated with mechanical vibration, sound, heat, light, etc.
Waveform - The shape of a wave, typically viewed on an oscilloscope.
Wavelength - The length of distance a single cycle o complete sound wave travels.
WCDMA - Refer to Wideband CDMA
White Noise - Random noise with equal energy per frequency covering 20 Hz – 20 kHz. This differs from Pink Noise as pink noise has equal energy per octave (rather than frequency). Based on how humans perceived the difference in sound from octave to octave, pink noise—rather than white noise – is the preferred test signal for frequency related measurements in mobile audio systems.
Whizzer - A cone found on some full-range tweeters, sometimes constructed of paper, commonly built into a megaphone woofer to increase treble response. Known as a cheap alternative and less accurate solution to other tweeter cone designs.
Wide Area Augmentation (WAAS) - An air navigation aid in the US developed by the Federal Aviation Administration to augment the Global Positioning System (GPS), with the goal of improving its accuracy, integrity, and availability. Originally intended for use by aircraft, WAAS is also available in many consumer GPS devices, including in-vehicle navigation systems.
Wideband CDMA (WCDMA) - A 3G CDMA derivative in which higher network data rates were possible over the base CDMA technology.
Wide Open Throttle (WOT) - The electrical condition present whenever the TPS is fully engaged.
WiFi - WiFi provides wireless connectivity over unlicensed spectrum (using the IEEE 802.11xx standards), generally in the 2.4, 3.6 and 5 GHz radio bands. WiFi offers local area connectivity to WiFi-enabled devices.
Wi-Max - A wireless technology based on the IEEE 802.11xx standard providing metropolitan are network connectivity for fixed wireless access at broadband speeds.
Window Roll-up - The term used for the feature that causes the window(s) on a vehicle to close upon arming, or open and close as part of a convenience feature of a security system.
Windows Media Audio (WMA) - A file extension used with Windows Media Player. WMA stands for Windows Media Audio. WMA is both an audio format and an audio codec. WMA was intended to be a competitor for the MP3 and RealAudio audio formats.
Windows Media Video (WMV) - Is the name of a series of video codecs and their corresponding video coding formats developed by Microsoft. ... WMV consists of three distinct codecs: The original video compression technology known as WMV, was originally designed for Internet streaming applications, as a competitor to RealVideo.
Wire - metal drawn out into the form of a thin flexible thread or rod. In car audio wire is typically made of some mixture of copper, or possibly aluminum.
Wireless Local Area Network - Is a wireless distribution method for two or more devices that use high-frequency radio waves and often include an access point to the Internet. A WLAN allows users to move around the coverage area, often a home or small office, while maintaining a network connection.
Wiring Harness - A specific application of wires and proprietary connectors to facilitate connection of electronic components in multiple locations. Also used to adapt replacement components into OEM applications for “plug in” compatibility.
WLAN - Wireless Local Area Network
WMA - Refer to Windows Media Audio
WMV - Refer to Windows Media Video
Woofer - A large dynamic loudspeaker that is well suited for reproducing bass frequencies, typically 6-18 inches in diameter when used in car audio applications.
WOT - Refer to Wide Open Throttle
X Axis - The principal or horizontal axis of a system of coordinates, points along which have a value of zero for all other coordinates.
Xmax - The maximum peak linear excursion of a driver, called Xmech as well. Also refer to Maximum Linear Excursion.
Xmech - Refer to Xmax or Maximum Linear Excursion
Xlim - Is expressed by Eminence as the lowest of four potential failure condition measurements: spider crashing on top plate; Voice coil bottoming on back plate; Voice coil coming out of gap above core; or the physical limitation of cone.
Y Axis - The secondary or vertical axis of a system of coordinates, points along which have a value of zero for all other coordinates.
Z - Total driver impedance.
Z Axis - The axis in three-dimensional Cartesian coordinates which is usually oriented vertically. Cylindrical coordinates are defined such that the -axis is the axis about which the azimuthal coordinate is measured.
Zone - The absence of output signal or output power.
Zero Output - The specific area of a security system’s coverage, or a term used to describe a specific trigger input such as “door zone” or “sensor zone.”
Cited Source Links:
- Advance Mobile Electronics Certified Professional Technician Study Guide
- Audioholics Online A/V Magazine “Pursuing the Truth in Audio and Video” (http://www.audioholics.com)
- Basic Car Audio Electronics Website (http://www.bcae1.com)
- CarStereo.Com (http://www.carstereo.com)
- Car Audio Classifieds! (http://www.caraudioclassifieds.org)
- Collins English Dictionary (http://www.collinsdictionary.com)
- Dictionary.com (http://www.dictionary.com)
- Eminence “The Art & Science of Sound” (https://www.eminence.com)
- Google (http://www.humanspeakers.com)
- Human Speakers “Music to your ears” (http://www.humanspeakers.com)
- Recording Connection “Recording Radio Film Connection & Casa Schools” (https://www.recordingconnection.com)
- Wikipedia “The Free Encyclopedia (https://en.wikipedia.org)