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