Inventors:
William Peil - North Syracuse NY
Joseph P. Hesler - Liverpool NY
Assignee:
General Electric Company - Syracuse NY
International Classification:
H04N 552
Abstract:
An automatic gain control system applicable to a television receiver is described. Synchronizing pulses contained in the video detector output are sensed to obtain a measure of the signal strength. This is done by applying the detected output, containing the pulses, to a threshold circuit to produce current increments representative of the excess of said pulses over the threshold. The current increments thus obtained are then applied to a non-linear amplifier which, as a bi-directional source of current, supplies charging or discharging current, depending upon signal strength variation, to an integrating network to obtain a smoothed gain control voltage. The circuit is characterized by both fast attack and fast release and may be used with or without external gating. It is suitable for general AGC control in a television receiver which must be substantially immune to aircraft flutter.