Ambiguity elimination in HF FMCW radar systems

Multiple waveform repetition frequency (WRF) is introduced as a solution to the range/Doppler ambiguity usually associated with high-frequency frequency-modulated continuous wave radars. The proposed pattern requires switching of WRFs while the target is being illuminated. The combination of WRFs is chosen to have a common multiple frequency greater than the expected target Doppler shift to resolve any Doppler shift ambiguities. An algorithm for the calculation of the Doppler shift of ambiguous targets is described. The performance of the new technique is evaluated by simulation. The results show that this technique can be used for ambiguity elimination of wideband ionospheric clutter