Micron 700 Series, Руководство пользователя

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Automatic Level Control System
Page
18
file:
tx700ins2master.doc
The level control is, in principle, a peak limiter. Its function is to prevent distortion due to overmodulation. Because
of the definitive design, it can be used as an audio AGC system with characteristics much improved over the
'automatic record' facility of most tape recorders. The center of the system is a voltage controlled variable gain
amplifier with a control range of 40dB.
The Automatic Level Control (ALC) system can be set so that it operates only in an emergency ('Normal' mode) or
so that it adjusts the gain to suit the user's voice level ('Automatic' mode) or so that it never operates at all, except
in an extreme emergency ('Low modulation' mode).
When used in the 'Automatic' mode, the control system sets the audio gain so that the average speech level is
about 9dB below peak modulation level. This leaves headroom for the short sharp transients, which occur
frequently in speech patterns. Having set the gain, the short transients pass without distortion and without further
need to change the gain.