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
Self-starter - Refer to Starter
Semi-Closed Aperiodic - This design is seldom seen in car audio applications, if at all. The enclosure design is of a typical sealed enclosure but the rear wall is replaced with a “leaky” dampening material instead of a rigid material that would typically be found. The internal air volume as well as the thickness and density of the dampening material used is what determines the enclosures tune, or the frequency response of the subwoofer.
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.
Sound Quality - is typically an assessment of the accuracy, fidelity, or intelligibility of audio output from an electronic device. Quality can be measured objectively, such as when tools are used to gauge the accuracy with which the device reproduces an original sound; or it can be measured subjectively, such as when human listeners respond to the sound or gauge its perceived similarity to another sound.
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
SQ - Refer to Sound Quality
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 - A device used to rotate (crank) an internal-combustion engine so as to initiate the engine's operation under its own power. Starters can be electric, pneumatic, or hydraulic. In the case of very large engines, the starter can even be another internal-combustion engine.
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.
Starter Motor - Refer to Starter
Status -The state a system is in at any given time, typically used in security system and remote starter descriptions.
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.
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