Automatic frequency control system for single sideband signal receiver

摘要

A single sideband receiver having a demodulator or mixer for carrier frequency demodulation in response to the output of a controllable variable frequency oscillator and an intermediate frequency demodulator for providing a demodulated signal is provided with an automatic frequency control system comprising a low pass filter for separating a low frequency portion from the demodulated signal a discriminator for detecting the level of the low frequency portion with respect to a predetermined level, and a circuit for controlling the frequency of the variable frequency oscillator in response to the detected relationship between the low frequency portion and the predetermined level.