Robust Wideband Waveforms for Synthetic Aperture Radar (SAR) and Ground Moving Target Indication (GMTI) Applications

High resolution SAR imaging and Ground moving target indicator (GMTI) radar are of crucial to intelligence surveillance and reconnaissance operations. High resolution SAR imagery are often realized at the expense of wide bandwidth waveform, and to achieve long dwells over a wideband width, often the operating frequency band overlaps with other co-band radars, and it becomes necessary to notch out those interference bands both in the transmit mode and the receive mode. Hence it is necessary to design constant envelope wideband transmit waveforms with spectral notches to null out the co-channel interference while maintaining excellent pulse compression properties to suppress sidelobes. A general solution to this problem is presented in this proposal with flexibility to generate nearly-constant envelope waveforms with significant null depths. Notched transmit waveforms lead to poor range resolution and to compensate that, three new receiver design strategies to suppress the sidelobes are also presented here. If the image scene is sparse, this a-priori information can be used in a fundamental manner by drawing on recent results on non-linear sparsity based image processing methods. Simulations results verifying the new algorithms, robustness issues and working with primes are other planned activities under this effort.