Coherent Demodulation of FrequencyShift Keying with Low Deviation Ratio

A coherent binary FSK modulation system is discussed, that has the following properties : 1) it is phase coherent ; 2) it has a low deviation ratio, h = 1/2; 3) it occupies a small RF bandwidth, typically only 0.75 times the bit rate, without need for intersymbol interference correction; 4) it uses as receiver a self-synchronizing circuit and a phase detector, which together achieve optimal decisions; and 5) its error performance is about 3 dB better than that of conventional FSK.