OFDM waveforms for frequency agility and opportunities for Doppler processing in radar

Frequency agility is an important feature when radar operates in jammed environments. With the development of the orthogonal frequency division multiplexing (OFDM) waveform in the communications, the opportunity for a new generation of digital agile radar rises. Old and expensive multi-channel analog agile front ends could be replaced by simpler and cost effective single channel transceivers where the coherent switches in frequency are done digitally. The novelty of the paper is to investigate an agile OFDM waveform so that Doppler can be solved despite the apparent frequency agility. The OFDM performance is assessed from the radar point of view, using the ambiguity function as a tool. Our approach considers a pulse burst, each pulse being implemented with OFDM chips. Three patterns for frequency agility from pulse-to-pulse are studied. Preliminary suggestions to accomplish coherent processing in an agile context are derived.