Autocorrelation and spectral density functions for ASK, PSK, and FSK with non-coherent or coherent split-phase code modulation

Pulse code modulation (PCM) involves transforming analog signals into a series of digitally coded pulses. The binary code is a widely used special case of the coding theoretically possible in a PCM system. One of the code structures used in binary coding is referred to as "bi-phase-level" or "split-phase". A technique used in generating a split-phase code utilizes the binary states "10" to represent a logic one and the binary states "01" to represent a logic zero. In a typical telemetry system the split-phase code is used to modulate the amplitude, phase, or frequency of a carrier. This thesis provides an analytical determination of the ensemble-average autocorrelation and the power spectral density of a carrier which is amplitude-shift-keyed (ASK), phase-shift-keyed (PSK), or frequency-shift-keyed (FSK) by a split-phase code. These transmission characteristics are first obtained for "non-coherent" modulation of the carrier by the split-phase code, and then obtained for "coherent" modulation of the carrier by the split-phase code. It is then shown that the time average of the autocorrelation and spectral density functions for the coherent cases reduce to the corresponding autocorrelation and spectral density functions for the non-coherent cases.