Multiplication by Square of Envelope as Means of Improving Detection Below FM Threshold

A theoretical analysis is presented of a novel form of FM demodulator where the FM signal is a flat band of Gaussian noise. The device offers an improvement over the demodulation capability of the conventional FM receiver in the region well below the threshold and the formulas governing its operation are simple, thus the manner in which changes in the modulation parameters Affect the performance can be easily determined. Threshold curves for high- and low-deviation cases are shown and compared with the performance offered by the conventional receiver and a frequency-feedback receiver.