Monopulse thresholding

Abstract

A monopulse thresholding processor and method for improving resolution by using the difference channel data to eliminate 'excess' sum channel returns. The processor may be used with a radar system that comprises an antenna, a transminer, a receiver for processing transmitted radar signals to produce radar returns therefrom, a log compressor for converting radar returns to log values, and a display for displaying the radar returns. The signal processor comprises a left sum and right sum generator coupled to the receiver for computing a left sum and a right sum from radar returns generated by the receiver. A pseudo-difference generator is coupled to the left sum and fight sum generator for generating pseudo-difference channel data. A beam sharpener is coupled to the left sum and right sum generator and to the pseudo-difference generator for beam sharpening the radar returns. A minimums generator coupled between the left sum and right sum generator and the beam sharpener for processing outputs from the left sum and right sum generator, for comparing them to a threshold value, and for providing an output signal comprising a minimum of the processed radar returns. The present invention generates a pseudo-difference channel using sum channel dam, thereby reducing hardware and software, and uses the difference channel as a threshold for keeping the sum channel returns. The sum channel returns are not modified by the difference channel returns if the threshold is exceeded. Therefore, sidelobes resulting from intermixing of the sum and difference channel returns are not possible, thereby eliminating generation of false targets. Also, because sum channel returns that exceed the threshold are not modified, these signals remain at their original strength. The present invention uses the pseudo difference channel data as a threshold on the sum channel data to perform beam sharpening that sharpens discrete target and clutter edges.