Television synchronous receiver

Abstract

A television synchronous receiver includes: a voltage controlled oscillator; a 90.degree. phase shifter for shifting the phase of the voltage controlled oscillator output by 90.degree.; first and second synchronous detectors for synchronously detecting in-phase and quadrature components of a video carrier signal using the voltage controlled oscillator output and the 90.degree. phase shifter output as synchronous carriers; first and second low-pass filters for filtering low frequency components of the first and second synchronous detector outputs within frequency ranges covering the base band of video and sound intermediate frequency signals; a phase detector for detecting the phase difference between the video carrier signal and the voltage controlled oscillator output from the first and second low-pass filter outputs; a circuit for feeding the phase detector output back to the voltage controlled oscillator; a signal amplifier for amplifying the first low-pass filter output; a signal converter for converting the signal amplifier output into a discrete-time signal; a clock generator for generating clock signals under the control of either television synchronizing signals or color burst signals separated from the signal amplifier output; a discrete-time system for processing the discrete-time signals and a signal reverse converter for reverse converting the discrete-time system output into continuous time signals. The receiver minimizes interference from an adjacent lower channel through the operation of the discrete-time system and generates video signals from the reverse converter without needing a varactor and inductor tuning circuit at the high frequency input section for removing adjacent lower channel signals.