Bidirectional notch filter for suppressing pulse modulated radio-frequency-interference in SAR data

Notch filter is one of the most popular techniques for Radio Frequency Interference (RFI) suppression in the wideband Synthetic Aperture Radar (SAR). In this work, we have wideband `TerraSAR-X' data affected by a near zero RFI (radio frequency interference), this RFI is modulated with a pulse wave, which creates side lobes in the frequency domain, and creates difficulty for filtering this kind of RFI. In this kind of data, the notch filter will eliminate the frequency, but create a transient response after the discontinuity which is a non zeros signal; in this paper, notch filter technique has been used in forward and backward range direction, so the transient effect will be created in different position of the images. Then we combine these two images using the best spectrum of the azimuth direction.