Digital filter designs for the pre-filter MTI technique with SAR

An optimal filter design technique for the prefilter moving target indication (MTI) method used in synthetic aperture radar (SAR) systems is presented. The technique is general, so that the data resampling ratio can be an arbitrary rational number. The digital filters have linear phase and are based on a two-stage design process involving an interpolation and a decimation. A filter is designed for each stage and the final optimized design is the convolution of the single stage filters. The proposed filters are sued when the pulse repetition frequency is a rational multiple of the clutter bandwidth. The filters show good clutter cancellation and minimal aliased overlap between MTI bands. An example is provided which demonstrates the effectiveness of the design technique