New approach to m.t.i. clutter locking

Proposals are made for new techniques, for clutter locking in m.t.i. radar systems, that adapt automatically to rapid variations in the clutter bias velocity with range. The proposed schemes are based upon what is believed to be the novel principle of correcting for the clutter bias velocity after the radar returns have been read-out from the vector canceller stores and demand no additional storage. The basic arrangements have been analysed in detail and procedures have been established with which to design systems to meet specified performances. An analysis based on generalised symmetric and skew clutter spectra has shown that the performances of these systems are very little affected by the shape of the spectrum. Using these procedures, a design has been derived for a clutter-locking arrangement for a pulse-staggering radar in which the mean Doppler frequency of the clutter can rise to 30% of the p.r.f. Addition of the proposed clutter-locking arrangement is expected to give an overall improvement factor which will be better than 23 dB at all Doppler shifts, and when averaged over all shifts will be 25 dB. In order to confirm the design analysis and to establish the degree of smoothing required in range, a program was written to simulate this particular design and to inject noiselike clutter having either a Gaussian or a highly skew spectrum. The results of this simulation corresponded satisfactorily with the predicted performance and yielded the result that the range smoothing required corresponded to only 4 range cells. The design awaits experimental verification.