Amti target/clutter discriminator

Abstract

In an AMTI radar of the type in which the difference between the phase of a current radar return signal and the phase of a radar return signal in a corresponding range bin of a preceding pulse repetition interval (PRI) is averaged over a number of range bins in the range vicinity of the current range bin, phase differences for current range bins are determined as being clutter-like or non-clutter-like by comparison with the previously-determined average phase difference by means of a rectangular distance discriminator which compares the normalized in-phase and quadrature components (cosine and sine, respectively) of the current phase difference with the normalized in-phase and quadrature components of the average phase difference in a rectangular distance discriminator. The rectangular distance discriminator sums the absolute values of the in-phase difference and the quadrature difference and compares them against a rectangular distance discriminant, which in a preferred embodiment is unity. When the summation of the absolute value of the in-phase and quadrature differences exceed the discriminant, the previously-determined phase average components are reintroduced into the phase averaging process; but when it is less than the discriminant, the current phase differences are introduced into the phase averaging process.