Characteristics of Adaptive Beamforming Methods in an HF Backscatter Environment.

摘要

The objective of this program is to investigate the advantages which may accrue to HF backscatter systems employing adaptive beamforming methods. The efforts were directed toward obtaining detailed information regarding the performance of time-domain adaptive beamforming methods in an HF backscatter environment. It was shown that the time scale of coefficient variation in an adaptive processor operating in this environment is the order of one second. Successful tracking of the P-vector algorithm under these conditions was demonstrated. The use of MTI clutter suppression filters at the subarray outputs, prior to adaptation, was investigated. No significant improvement was observed with the use of these filters on experimental data. A preliminary investigation into the effects of receive array aperture size on adaptive array performance has been carried out. It was shown that the presence of fading nulls can significantly effect the determination of optimal subarray location and spacing in an HF environment. In general, the adaptive beamformer performance was found to be less dependent upon array geometry than was the case for conventional processing.