EMI repair in pulse doppler radar

The electromagnetic spectrum traditionally used by radar systems is under pressure from the growing global need for wireless communications services. Additional factors, such as the technology shift towards high duty-cycle solid-state transmitters and phased arrays using uniformly illuminated transmit apertures, are making the radar-to-radar electromagnetic interference problem more important than ever before. Such high-level electromagnetic interference (EMI) to radar can result in degraded performance, and for modern high-performance pulse doppler radars the problem is aggravated by the need to use coherent dwells of many pulses for coherent suppression of strong clutter returns. Just a few high-level EMI returns can severely desensitize the radar across many range cells in the pulse repetition interval (PRI) and even result in complete loss of information due to receiver saturation effects. This paper will describe a simple doppler repair technique for effectively reconstructing lost data within a pulse doppler radar coherent dwell and thus preserve clutter suppression and sensitivity in a severe EMI environment.