Phased array receiver filtering and demonstration of digital beamforming on measured wideband data

The MCWESS array is a 256-element, 16-channel phased array receiver which was recently built for research purposes in the Air Force Research Laboratory (AFRL) Sensors Directorate. Current research at AFIT includes signal processing techniques for adaptive wideband digital beamforming. To support the research, with the help of engineers at AFRL, wideband data was collected using the MCWESS array. The signals collected were received from three different, spatially separated, bandlimited, thermal noise sources. The noise sources have the wide bandwidth desired to support wideband digital beamforming (DBF) research. When the resulting data from the receiver did not correlate with the transmitted noise signal as expected, a closer examination of the set hardware processing done on the signal revealed the signal´s true nature. This paper outlines the systematic process followed to determine the actual content of the data, shows that direction of arrival (DOA) estimation is possible when using wideband beamforming techniques even on only a partial signal spectrum, and demonstrates wideband beamforming on measured data using a time reversal beamforming algorithm developed by AFRL.