PICTURE CARRIER CONTROLLED AUTOMATIC GAIN CONTROL CIRCUIT FOR CABLE TELEVISION INTERDICTION OR JAMMING APPARATUS

摘要

An off-premises negative or positive trap jamming cable television or interdiction system includes a picture carrier controlled automatic gain control circuit (231). A broadband television signal output o f a variable gain device (230) is distributed by a radio frequency signal splitter (280) to a number of subscribers. A portio n of the output of the variable gain device (230) comprising at least two contiguous television channels is passed to a power level detector (502). A detected power level is compared with a predetermined power level reference (504) for adjusting the gain of t he variable gain device (230). The predetermined power level reference is set to equal the attenuation between the off-premises equipment and the subscriber premises plus the desired level at the entrance to the subscriber's premises. The power level of a jamming or interdicting signal for denying access to unauthorized television programs is set to fall within a predetermined range of power levels related to the predetermined power level reference.