Abstract :
Conventional backward-acting AGC circuits acting fast enough to counteract rapid fading will, if stable, suppress neighboring voice frequencies. However, forward-acting AGC is inherently stable, so it can be made very fast by inserting a sharp cut-off filter in the control path. This permits the suppression of 200 cps. fading with negligible effect on the 300-3,000 cps. voice band. Analysis and tests show that fading modulation products are suppressed by about 20 db.
