Random noise detecting system and method

摘要

A system and method for detecting the level of random noise contained in a band-limited amplitude-modulated signal. A sychronizing signal is produced which is pi /2 out of phase with respect to the carrier of the amplitude-modulated signal. The amplitude-modulated signal and the synchronizing signal are multiplied together. Only a low frequency component is extracted from the multiplication output, and the low frequency component is taken as an indication of the level of the random noise contained in the amplitude-modulated signal.