Research in adaptive beamforming for satellite communications

The results of an investigation of adaptive interference cancelling techniques for use with satellite borne arrays of sensors are presented in the report. "A Hybrid Array' utilizing both a pointing vector and an internally generated reference is analyzed. The steady state and transient properties of the processor are presented showing speed of response, signal to interference plus noise ratio, and reduced sensitivity to pointing errors over schemes heretofore used. Also developed is the sensitivity to random amplitude and phase error in the pointing vector. A means by which the pointing vector can be obtained utilizing a pilot ground source is described and analyzed. In addition, analyses are presented on improved methods using only an internally generated reference. One scheme is analyzed in which non-oscillatory weights are obtained even when an imperfect reference is generated. This analysis is carried out assuming no interference, paralleling earlier work on a related scheme in which oscillatory weights were obtained. A second analysis is presented on a method which corrects the cause for unstable weights. This analysis is carried out with desired signal, interference, and noise present.