A new coherent processing method for frequency agility

For conventional pulse-Doppler radars, the frequency of the radar must remain constant over the whole coherent integration time. For high-frequency surface-wave radar, the coherent integration time can be as long as several minutes. This means that the radar must be permitted to transmit in a particular frequency channel for several minutes. This presents a problem when there is a requirement for the radar to switch to another frequency whenever there are other users in the radar band. In this paper, a robust and effective algorithm is adopted to maintain coherent integration gain while operating in a frequency-agility mode.