Television reciever with a phase detector having dual phase determining and correcting networks

Claim 1

A signal receiver of the type adapted to receive a composite signal including a first signal component modulated on a carrier wave and a second signal component frequency modulated on a subcarrier wave, said receiver comprising first and second signal paths, means For applying said composite signal to said first and second paths, first detector means in said first path for producing a first output signal at the subcarrier frequency, a phase determining network in said second path, said phase determining network producing first phase variations of the modulated subcarrier wave in said path as determined by departures of the central frequency of said subcarrier wave from an assigned value and second phase variations of said modulated subcarrier wave as determined by frequency modulations of said subcarrier wave, second detector means in said second path coupled to the output of said phase determining network for producing a second output signal at the subcarrier frequency having composite phase variations as determined by the phase variations produced by said phase determining network, phase detecting means coupled to the outputs of said detecting means for producing an output signal, and a phase correction circuit interposed between the output of one of said detector means and said phase detecting means, said phase correction means comprising means for generating phase variations of the subcarrier signal applied thereto as determined by the frequency variation of the said subcarrier signal about its nominal value, said phase variations being in a sense opposite to the said second phase variations imparted to said subcarrier wave by said phase determining network thereby to produce an output signal having a value as determined by said first variations of said modulated subcarrier wave.