Radio carrier wave presence detector - operates without using pilot signal by dividing IF signal into wo and using set of bandpass filters

摘要

The carrier signal detector detects the presence or absence of a carrier without necessarily using a pilot signal. A part of the IF signal is coupled out and it is passed over two channels each containing a limiter (B), a BP filter (F2, F3), a diode rectifier (D) and an RC circuit. The first channel also contains an additional BP filter (F1) at its input. The outputs of both channels (ie the outputs of the RC circuits) are compared in a comparator (K). The a series of given relationships exists between the filter bandwidths.