Abstract
This paper deals with the theoretical analysis and the experimental results of the characteristics of an improved synchronous detector in which the reference carrier phase is varied according to the phase modulation component of the received signal.
It is shown that the characteristics of this proportional-phase synchronous detector are more suitable for video demodulation compared to those of the envelope detector which produces quadrature distortion or of the conventional constant phase synchronous detector which generates differential phase resulted from the phase modulation component produced in the television transmitter by its AM to PM conversion characteristics.
As the reference signal in the improved synchronous detector is generated from the received signal by the amplitude limiter consisting of ring connected diodes to reduce the phase shift error of the circuit, the experimental visual demodulator has been realized with simple construction and improved stability.
