Noise detection in a frequency demodulated fm - broadcast signal

摘要

The noise in a frequency demodulated audio signal is detected on basis of the characteristics of the stereo-multiplex signal to obtain a very reliable information that can be used for the sliding stereo-mono transition, noise blanking and a de-noising of the stereo-difference signal. A noise signal (νd,l(t)-νd,u(t) or νd.u(t)-νd.l(t)) is calculated by subtracting one sideband of the stereo-difference signal from the other sideband of the stereo-difference signal and as a direct measure for the quality of the signal generating the variance (σ2νd) of the noise signal by squaring and thereafter averaging the noise signal.