Determination of Modulation Indexes and Design of Two-Channel Coherent Communication Systems

This paper presents an approach to the determination of modulation indexes for 2-channel, phase coherent communication systems (of the Mariner type). The method is based upon a mean-squared error criterion and can be used to apportion the total transmitter power between the carrier signal, the modulated data subcarrier, and the modulated sync subcarrier. Further, a method is given which enables the communications engineer to determine the system data rate which will yield a predetermined bit-error probability. The method takes into consideration errors due to radio-frequency carrier phase jitter, subcarrier reference phase jitter, and jitter about the instants in time with which the modulation may change states. The results are useful for designing coherent communication systems for space applications.