Radio Frequency Interference Suppression Algorithm Based on SOCP in OTHR

Abstract

Sky wave over-the-horizon radar is easily affected by radio frequency interference (RFI) since it shares the high-frequency band with many radio services. Among the existing methods, spatial filtering method is ineffective to suppress the mainlobe RFI, and time-frequency method usually weakens the target signal while rejecting RFI. In this paper, we notice that, before matched filtering, RFI is usually a narrowband signal but the target echo is a broadband signal. According to this feature, an efficient RFI suppression algorithm is proposed by designing a new matched waveform based on a constrained optimization problem. Further, we show that this problem can be reformulated in a convex form as the second-order cone program and solved efficiently using the well-established interior point method. Compared with the existing methods, the proposed algorithm can suppress the RFI from any direction of arrival and get a higher output signal-to-interference-plus-noise ratio. Experimental results demonstrate that the proposed algorithm outperforms the existing methods.