An Efficient Noise Immune Sync and AGC Circuit for Television Receivers

Impulse noise interference, such as may be caused by sparking electric motors or automobile ignition systems, can interfere with the performance of a television receiver in the following principal ways: First, the impulses appear directly in the picture; second, the synchronization separator input circuit may charge up to such an extent that the picture loses synchronization; third, the impulses may provide false information to the AGC system thereby causing a sharp reduction receiver gain. Of the three, the latter two effects are by far the more serious. Consequently, noise ``suicide'' or noise inverter circuits, for the protection of the sync separator and AGC circuits have been widely used.