Model-Based Array Processing

This report discusses an array processing technique that allows optimal source amplitudes and arrival angles to be determined from the data received on arbitrary arrays. Used with either a one- or two-planewave fit to arbitrarily spaced linear arrays, the method shows superior performance to conventional beamforming when more than one source is present within the angular resolution of the array. With such situations becoming more and more likely as operating frequencies are driven to lower values, in an effort to increase detection ranges, this new approach can be used to coherently subtract strong arrivals from received data, allowing the detection of additional weak arrivals in close angular proximity. In the case where a planewave arrives at an arbitrary two-dimensional array from a moving source, a similar technique yields optimal values of the source amplitudes of the planewave, as well as the starting and ending positions of the moving source. The new processing thus performs the functions of a combined beamformer and tracker in such a way that the total error over the observation interval is minimized.