Synchronous phase marker and amplitude detector

摘要

Disclosed is an electronic circuit for determining the phase difference between an input signal and a reference signal where both signals are of the same frequency. Furthermore, the circuit provides an amplitude output indicative of the input signal even when that signal is obscured by noise. A chopper is supplied with the obscured signal input and a reference signal input and provides an output to an integrator which provides a control voltage for a voltage controlled phase shifter which supplies an out of phase input to the chopper. The input to the voltage controlled phase shifter is of the same frequency as the signal obscured by noise. A further output of the voltage controlled phase shifter is 90 DEG out of phase with respect to the reference supplied to the chopper and thus is in phase with the signal obscured by noise and provides the desired marker output. This marker output is also supplied as a reference to a second chopper which is also supplied with the obscured signal as an input. The output of the second chopper after suitable amplification, is proportional to the amplitude of the signal that is buried in noise. Thus, as long as the frequency of the signal buried in noise is known and supplied in the form of a reference signal, the phase and amplitude of the signal can be determined with the synchronous phase marker and amplitude detector.