Abstract:

In over-the-horizon radar (OTHR), the traditional methods suppress the radio frequency interference (RFI) in space or time domain after matched filtering, and they tend to suppress the target around the RFI at the same time. We notice that RFI and the target signal are the similar narrowband signal after matched filtering, so it is difficult to distinguish them in the time domain or frequency domain; while before matched filtering, the target signal is a wideband signal, and the RFI is a narrowband signal. Based on these features, a RFI suppression algorithm based on interference elimination in the frequency domain is proposed. The algorithm firstly suppresses the sea clutter in the Doppler domain and transforms the signal into the frequency domain, detects the frequency position of RFI in the frequency domain, and then sets the frequency position to zero in the frequency domain of the original signal, finally transforms the signal to the time domain. Compared with the traditional methods, the proposed algorithm can effectively suppress the RFI and protect the target signal. Experimental results verify the superiority of the proposed algorithm.