The Response of a Quasi-SSB-FM System to Noise

In this paper we introduce the concept of a quasisingle-sideband frequency modulation (SSB-FM) signal and show that this signal has approximately the same bandwidth as an SSB-FM signal but does not fade and peak as sharply as an ordinary SSB-FM signal. The threshold of a sinusoidally modulated SSB-FM signal is calculated and is shown to be significantly poorer than the threshold of an ordinary FM signal. In addition, the output signal-to-noise ratio (SNR) above threshold is calculated for a Gaussian modulated SSB-FM signal. The output SNR is smaller than that obtained for ordinary FM. It is concluded that SSB-FM offers many disadvantages and few advantages when compared to FM.