Doppler processing for coherent “chirp” radars

Northern Radar Systems Limited has built a high frequency radar system at Cape Race, Newfoundland, for over-the-horizon (OTH) detection of targets. The radar uses a frequency modulated interrupted continuous wave (FMICW) signal, specifically developed for long range target detection. For the detection of fast targets, conventional processing is constrained by the limited time that a target is present in a range cell. This problem can be eliminated by using velocity matched filters to process the FMICW signals. The analytical derivation of these filters is presented, followed by numerical simulations of the filter performance. Results of OTH detection of low-flying aircraft using the high frequency ground wave radar (HF-GWR) system are also presented