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| • | Accessory (position) - Refers to the position of the key in the ignition switch; A wire showing 12 Volts (+) when in this position. |
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| • | Acoustic Absorption - The sound deadening properties of any substance, measured in sabine units. One sabine is equal to the absorption of 1 square foot of surface which will absorb all incident energy. |
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| • | Acoustic Feedback - A squealing sound when the output of an audio circuit is fed back in phase into the circuit's input. |
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| • | Acoustical Energy - Energy consisting of fluctuation waves of pressure called sound waves. |
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| • | Acoustics - The study of sound. The science of production, effects, and transmission of sound waves through various mediums and the effects of absorption, diffraction, interference,
reflection, and refraction. |
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| • | Active Arming - A method for arming a security system that requires some action such as pressing a button on a remote transmitter or entering a code on a keypad |
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| • | 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. |
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| • | Air Gap - The space between the top plate and the pole piece. This is where the voice coil sits. |
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| • | 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. |
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| • | Alternate-Channel Selectivity - A measurement of a tuner's ability to select one radio station's signal and reject the signal of another radio station two channels (0.4 Mhz) away. Measured in decibels, the higher the number the better. |
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| • | Alternating Current (AC) - An electric current that reverses direction at regular intervals. Measured in Volts AC at Hertz, example: 110 volts AC 60 Hz. |
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| • | Alternator - A device that is turned by a motor to produce AC voltage, which is then rectified (turned into DC) and used to supply voltage to the vehicle's electrical system. |
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| • | Alternator Whine - A whining that is heard when the RPMs of an engine increase. The noise is usually the result of a voltage differential created by more than one ground path or a poor ground path (ground loop). |
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| • | American Wire Gauge (AWG) - A standard of the dimensional characteristics of wire used to conduct electrical current or signals. AWG is identical to the Brown and Sharpe
(B & S) wire gauge. |
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| • | Ammeter - An instrument that measures the magnitude of an electric current in amperes. |
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| • | Ampere (amp) - A unit that defines the rate of flow of electricity (current) in a circuit. |
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| • | Amplification - The increase in signal level, amplitude or magnitude. |
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| • | Amplifier - 1 A device which increases the level of a signal by increasing the current or voltage. 2 May also be used to isolate or control a signal and even decrease the level as in a line output converter. |
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| • | Amplifier, Power - An amplifier designed for driving loudspeakers and having a higher power output than a line amplifier or preamplifier. |
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| • | Amplitude - The maximum value of a periodically varying quantity. |
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| • | Amplitude Modulation (AM) - The encoding of a carrier wave by variation of it's amplitude in accordance with an input signal. AM Stereo |
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| • | 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) |
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| • | 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). |
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| • | Analogous - Alike in certain ways. Similar in function but not in origin or structure. |
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| • | 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 |
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| • | Antenna - An apparatus used for sending and receiving radio waves, usually constructed of metal. |
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| • | 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. |
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| • | Attenuator - A device to decrease or increase the strength of a signal. |
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| • | Auto Eject - Feature of a cassette player that ejects the tape when it has finished playing one side. |
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| • | Auto Loud - Automatically provides low frequency boost for listening at low levels. |
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| • | Auto Memory - A tuner feature that automatically finds the strongest stations in the local area, and places them in preset memories. |
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| • | 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. |
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| • | Auto Reverse - Feature of a cassette player that automatically plays the reverse side of a tape when one side has reached the end. |
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| • | 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. |
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| • | Automatic Gain Control (AGC) - A circuit that continuously adjust the recording amplifier gain to maintain a relatively constant recording level. |
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| • | Azimuth - The perpendicular alignment of the tape to the head of a tape player / recorder. |
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