Differential Detection of Binary FM

It has been found possible to realize excellent practical performance in FM transmission of binary data by use of a detector in which the signal is multiplied by a delayed replica of itself. This method has been called "differential detection" on account of its resemblance to the scheme of t h a t name in widespread use as a detector of phase-modulated waves. The name "product demodulation" has also been applied. We can regard the detector either as a particular kind of frequency discriminator or as a phase comparator operating on the phase changes inherent in an FM wave. T h e former concept is suitable for a steadystate analysis, while the latter is more convenient in the study of signal transitions.