Space time adaptive processing for high PRF radar

High pulse repetition frequency radars are employed for airborne applications due to their capability to place high closing-rate targets in the clutter-free region. The highly ambiguous range returns, may however, cause low Doppler targets to compete with near-range strong clutter. It is shown that STAP techniques are required to reject the near-range clutter returns which mask low Doppler targets. As a result of range ambiguity of the HPRF radar, the sample support for estimating the array covariance matrix is limited, leading to an ill-conditioned problem. Three methods are considered to resolve this problem: (1) a modification of sample matrix inversion (SMI) referred to as pseudoinverse SMI, wherein the pseudoinverse is applied in lieu of the covariance matrix inverse, (2) loaded SMI, and (3) the eigencanceler. It is shown that the eigencanceler and loaded SMI perform well, with the eigencanceler slightly outperforming loaded SMI. Pseudoinverse SMI does not perform satisfactorily