Circuit for cancelling sinusoidal pilot signal contained in composite signal

摘要

A DC voltage having a magnitude proportional to the amplitude of a pilot signal in a composite signal which is employed in the commercial FM stereo broadcasting is generated and divided to plural voltage levels through a resistor voltage dividing network having a plurality of outputs. The output voltages of the voltage dividing circuit network are reciprocatingly multiplexed to a common terminal over a multiplexing cycle in response to the pilot signal. A sinusoidal-wavelike staircase waveform signal having a fundamental frequency the same as the frequency of pilot signal is taken out of the common terminal by appropriately setting values of resistors in the voltage dividing circuit network. The sinusoidal-wavelike staircase waveform signal is smoothed to generate a sinusoidal cancel signal which is then combined with the composite signal to cancel out the pilot signal in the composite signal.