Multi-dwell matched-field altitude estimation for over-the-horizon radar

In previous work, electromagnetic matched-field processing was proposed for estimating aircraft altitude with over-the-horizon radar using a single radar dwell. Although this approach exploits the altitude dependence of unresolved multipath returns in complex delay-Doppler space, its performance suffers in situations where the coherent integration time (CIT) of the radar is short. To overcome this limitation, this paper presents a matched-field estimation approach which uses multiple consecutive dwells on the target. The technique exploits the altitude dependence of dwell-to-dwell shape changes in the complex delay-Doppler multipath return. Monte Carlo simulations results indicate that using short CIT's, moderate signal bandwidth, and a 30 second revisit rate, multi-dwell matched-field estimation can achieve better than 5,000 ft. accuracy after as few as four radar dwells. The results of processing actual radar data for a high flying commercial aircraft of known altitude are presented which serve to validate the technique.