PHASE CONTROLLED DEMODULATION SYSTEM FOR DIGITAL COMMUNICATION

摘要

A phase controlled demodulation system for digital communication includes a quadrature detector for receiving a modulated digital signal and generating therefrom a pair of I and Q demodulated signals. A phase difference detection and filter circuit detects a phase difference between the I and Q demodulated signals, and another circuit detects a carrier-to-noise ratio of one of the I and Q demodulated signals. A further circuit detects a ratio difference between the detected carrier-to-noise ratio and a predetermined value, and a voltage controlled oscillator responsive to the detected phase difference and the detected ratio difference generates a carrier as a replica of the carrier of the received digital signal and applies the carrier to the quadrature detector.