Telex ISP-100 manual Glossary

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GLOSSARY
A to D	Analog to Digital. Conversion of an analog signal to a digital representation.
Amplitude factor	See CREST FACTOR.
Attack	The rise of a musical note from zero to full volume.
Attack time	The time required for an applied signal that suddenly increases in amplitude to
	reach 1-(1/e), that is, 63.2% of its final, stable value.
Attenuate	To reduce in amplitude.
Attenuation characteristic	The decrease of signal amplitude versus frequency. It is usually expressed in
	decibels per octave.
Attenuation constant	See ATTENUATION CHARACTERISITIC.
Attenuator	A device for reducing signal amplitude in precise, predetermined steps, or
	smoothly over a continuous range.
Audibility	The quality of being able to be heard. In a healthy listener, the threshold of
	audibility is extremely low; at the threshold, the pressure of a sound wave
	varies from normal by approximately 10-4pascals. The frequency range of
	human audibility extends roughly from 20 Hz to 20 kHz.
Audible	Hear or capable of being heard.
Boost	To increase the overall level of a signal.
Clipper	A circuit whose output voltage is fixed at a value for all input-voltages higher
	than a predetermined value. Clippers can flat-top the positive, negative, or
	both positive and negative peaks of an input voltage.
Clipping	1. Leveling off (flat-topping) a signal peak at a predetermined level. Also see
	CLIPPER. 2. In audio practice, the loss of syllables or words because of
	cutoff periods in the operation of the circuit (usually caused by overdriving a
	stage).
Compress	To reduce the bandwidth or dynamic range of a signal.
Compression	1. The reduction of output signal amplitude as input-signal amplitude rises. 2.
	Processing of a signal to increase low-level components and thereby raise the
	average power level. Usually a logarithmic function.
Compression ratio	In a system containing compression, the ratio A1/A2, where A1 is the gain at a
	reference-signal level and A2 is the gain at a specified higher signal level.
Compressor	A circuit or device which limits the amplitude of its output signal to a
	predetermined value in spite of wide variations in input signal amplitude.
	Unlike a CLIPPER a compressor does not flat-top output signal peaks.
Crest factor	For an AC wave, the ratio of the peak value to the rms value. The crest factor
	of a sine wave is equal to the square root of 2, or 1.4142126.

Glossary