Abstract: A security system for monitoring an area under surveillance includes a transmitter for generating radio frequencies (RF) signals when actuated using an actuator. A sensing station receives the RF signals from the transmitter. A monitoring station generates video signals of the area under surveillance and provides one end of a duplex audio communications system. A control station, coupled to the sensing station and the monitoring station, actuates the monitoring station in response to the RF signals sensed by the sensing station. The control station includes an opposite end of the duplex audio communications system and a display for displaying the video signals.

Abstract: A pseudo-random bit generator forms a portion of the pseudo-random code generator, and provides square wave output bits over a defined frequency spectrum on a plurality of parallel output lines. The bits present on a selected number of output lines in sequence define a binary number, which is compared with an accumulated count present in a counter driven by a clock running at a predetermined frequency. A correct comparison resets the counter, shifts the pseudo-random bit generator, and shifts a past-history shift register which contains a portion of the output of the pseudo-random code generator. The output from the past-history shift register, and the square wave output bits on certain other parallel output lines from the random bit generator are applied as inputs to respective logic probability circuits.