Abstract: The values of a binary frequency error signal are periodically transmitted to the generator to be controlled, through a narrow band channel. A sequence detector circuit records the successive received values of the frequency error signal and as a function of the last two received values, controls a modulated pulse generator circuit in order to form a variable-amplitude correction signal. The amplitude of the correction signal is reduced with each change in the value of the frequency error signal received, whose changes in value reproduce changes of a phase error signal.

Abstract: The comparator comprises a circuit for detecting the sign of the phase-shift of the reference signal relatively to the second signal for a predetermined phase of the latter. It delivers a corresponding binary phase difference signal.A second circuit selects those changes in values of the phase difference signal which occur for a phase of the reference signal comprised in a predetermined phase interval, and are thus surely representative of a change in the sign of the frequency difference.