Approaches to RF interference suppression for VHF/UHF synthetic aperture radar

An increasing amount of interest has developed in VHF/UHF SAR applications. Unfortunately the VHF-UHF portion of the spectrum is already in heavy use by other services, such as television and mobile communications. Even in remote locations the interference power often exceeds receiver noise by many dB, becoming the limiting factor on system sensitivity and severely degrading the image quality. This paper addresses the problem of radio frequency (RF) interference and its impact on SAR imagery. Several RF interference suppression methods are described and discussed. These include spectral estimation and coherent subtraction algorithms, as well as various filter approaches. The least-mean-squared (LMS) adaptive filter is described in detail, and its effectiveness in suppressing RF interference is demonstrated on simulated data and on real P-band data