Selection technique for subcarrier frequencies and modulation indices

This paper presents a simple technique for the design of a phase-modulated residual carrier communications link to mitigate mutual interferences among the channels for optimum system performance. The emphasis is on two data channels which am operated simultaneously with a ranging signal. The data channels employ PCM/PM and PCM/PSK/PM modulation schemes for high and low data rate channels, respectively. The technique proposed selects the optimum (1) subcarrier frequency to reduce the interference between the two data channels, and (2) modulation indices to suppress the undesired signals in the data channels. Further, this technique also provides an optimum balance of power between the two telemetry data channels and the ranging channel. Although this technique is proposed to optimize the performance degradation for two data channels, generalizations can be made for more than two data channels. To make the generalizations easier, this paper presents an algorithm based on the proposed technique, along with numerical results demonstrating its applicability. >