COMMUNICATION RECEIVING APPARATUS EMPLOYING SEVERAL SAMPLES OF BASEBOARD NOISE TO DETECT AN INCOMING SIGNAL AND TURN ON THE APPARATUS

摘要

Communication receiver employing squelch circuitry to turn on the receiver during receipt of an incoming signal. The RF and IF sections of the receiver are turned on periodically and the baseband noise originating in the IF limiter is sampled. The baseband noise pulses during the sample period are counted. If the number of pulses is less than a certain number, this information is stored as an indication that an incoming signal is present. If the certain number of pulses are counted during a period, an indication that an incoming signal is not present is stored. Based on several stored indications decision circuitry determines whether or not an incoming signal is present and causes operating power to be supplied to all sections of the receiver only if the determination is made that an incoming signal is present.