On the Spectral Properties of Single-Sideband Angle-Modulated Signals

Abstract

The representation of single‐sideband angle‐modulated carriers as originally given by Bedrosian is generalized through the functional and spectral notions of distribution theory. In this treatment the class of related modulating signals is extended to rather general types of distributions, and spectral criteria and iteration algorithms are established by which such modulating signals can be recovered from bandlimited components of the modulated carriers.

Characteristics of demodulated narrowband SSB-FM signals

“…Overmodulation generates in-band distortion, which increases gradually with modulation depth. This distortion mostly affects the negative values of the modulating signal, and consists of positive 'clicks' appearing simultaneously with envelope minima (in this case the signal may be recovered by a known iterative process [15]; however, this requires complex processing at the receiver). A reduction in distortion might therefore be achieved by suppressing the modulated signal whenever large envelope dips are detected, although the effectiveness of this approach will depend on the nature of the modulating signal.…”