In this paper, a detailed quantitative examination of spectrum packing efficiency of several modulation schemes is performed using power spectral analysis. Examples are given for a typical communication satellite uplink and downlink. From the results of this analysis, the most promising candidate modulation schemes are selected and identified for a more accurate time-domain analysis.

This paper presents a beamforming technique using a probabilistic characterization of the direction of arrival (DOA). The underlying distribution of the desired signal DOA can be known a priori or can be completely random with a finite support. The beamforming processor iteratively computes the "a posteriori" probabilities for each assumed DOA and weights each optimum beamformer steered at the assumed direction to arrive at a composite weight vector. The theoretical background is derived and simulations are carried out to illustrate the effectiveness and robustness of this novel beamformer. Finally, an application to diversity processing in CDMA systems is briefly discussed.

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.>