Target angle estimation from randomly sampled adaptive subarray sum and difference beams

Abstract

Rejection of interfering jamming signals using phased arrays with a large number of elements requires the use of randomly spaced subarrays for computationally efficient FPGA implementation. Now we extend this concept to monopulse radar for target angle estimation using sum and difference channels. For estimating target elevation and azimuthal coordinates, sum and difference channels are required for vertical and horizontal directions. Implementation of a fully adaptive system with sum and difference channels in both polarizations is problematic from a data bandwidth and computational point of view. Particularly data speed requirements can create bottlenecks when a fully adaptive design spans more than one logic device. A randomly sampled subarray architecture is employed to solve this problem. Fully adaptive sum and difference channels are distributed into structures of sparsed subarrays employing either 8by8 and 12by5 subarray configurations. The constrained adaptive algorithm is employed for the sum and difference channels to mitigate jammer effects in target angle estimation. Performance of the adaptive subarray angle estimators is quantified in the presence of a sweeping jammer.