Design of a communications system for multiple telemetry data channels operating simultaneously with a coherent turn-around ranging channel

A simple technique to design a phase-modulated (PM) residual carrier communications link for optimum performance is presented. The emphasis is on two data channels which are operated simultaneously with a ranging signal. The data channels use PCM/PM and PCM/PSK/PM modulation schemes for high and low data rate channels, respectively. The technique proposed selects the optimum subcarrier frequency to minimize the interference between the two data channels, and modulation indices for optimum balance of power between the two telemetry data channels and the coherent turnaround ranging channel. The selected set of optimum modulation indices will allow for the specified bit error rate (BER) degradations in the two data channels. Although this technique is proposed to optimize the performance degradation for two data channels, generalizations can be made for more than two data channels