Service manual

STP 11-25R13-SM-TG
Glossary - 12
Section II
Terms
American Wire Gauge (AWG)
Designator for a given wire based on classification according to diameter.
ammeter
Current indication meter.
amplifier (amp)
A device or circuit that can increase the magnitude or power level of a time-variable signal without
distorting its wave shape.
amplitude
The magnitude of variation in a changing quantity from its zero value.
amplitude modulation (AM)
The process of impressing information on a radio frequency signal by varying its amplitude.
anhydrous
Free from water (as in ethyl alcohol).
anode
The positive electrode such as the plate of a vacuum tube.
aspect ratio
(1) The numerical ratio of picture width to height. (2) The proportions of the television screen and
therefore of all television pictures: three units high and four units wide, for HDTV 9 X 16.
astigmatism
The uneven foreground and background blur that is in the image
attenuation
Reduction or loss of signal strength, measured in decibels; opposite of gain.
audio test signal generator (ATSG)
Used in the testing, troubleshooting, and adjustment of audio frequency circuits.
automatic frequency control (AFC)
A method for keeping a receiver or transmitter at the desired operating frequency.
automatic gain control (AGC)
A type of circuit used to maintain the output volume of a control receiver constant, regardless of variations
in the signal strength applied to the receiver.
average picture level (APL)
The average picture level, with respect to the blanking level, during active picture scanning time
expressed as a percentage of difference between the blanking and reference white levels.
back porch
That portion of the composite video signal which lies between the trailing edge of the horizontal sync
pulse and the trailing edge of the horizontal blanking pulse.