A compact library of discrete phase-only spatial filters for use in a digital or optical correlator has been constructed which discriminates between TABILS24 MV0045 and MVO294 by a factor of 10 using signal-to-clutter ratio as a measure of performance. This is a combined discrimination ratio of more than 20. This library of filters can be stored in 320 K or less of memory. These filters have been designed to give a stable recognition signal to their respective true targets over a wide range of rotation angles. More importantly, they also give strong recognition signals to target aspects which straddle images used in the filter training sets. This stability arises from a simple processing of the radar imagery before it is inserted into the correlator.
Robert R. Kallman,
"Invariant phase-only filters for TABILS24 millimeter-wavelength radar data", Proc. SPIE 1960, Automatic Object Recognition III, (15 October 1993); doi: 10.1117/12.160626; https://doi.org/10.1117/12.160626