Fast and slow time scale clutter cancellation

Abstract

Target detection in the presence of non stationary clutter is improved by a radar receiver on a moving platform for detecting a target using a plurality of short coherent arrays and a plurality of long coherent arrays synthesized from the short coherent arrays overlapping the target. The target is obscured by slow scale clutter and fast scale clutter in the vicinity of the target. The radar receiver has a plurality of subapertures overlapping to acquire radar returns reflected from the target during the arrays, an analog to digital converter for each of the subapertures to convert the radar returns into digital radar returns for a plurality of range bins covering the target, the slow scale clutter and the fast scale clutter; and a digital computer for performing steps of SAR image creation, further enhanced by thresholding short array magnitude data, computing a time domain component of threshold filters using the thresholded short array magnitude data then coherently subtracting the time domain component of threshold filters from the short arrays, and using the result to synthesize long coherent arrays. A Space Time Adaptive Algorithm (STAP) is applied to the long coherent arrays thus obtained to suppress slow and stationary clutter. The short coherent arrays are between 10 and 400 milliseconds long. The long coherent arrays are between 400 and 4000 milliseconds long.