Wideband signal design for over-the-horizon radar in cochannel interference

Abstract

Ship detection in heavy sea clutter is a big challenge for over-the-horizon (OTH) radar. Wideband signal is helpful for improving range resolution and the signal-to-clutter ratio. In this paper, to support OTH radar employing wideband in cochannel interference, we propose environmental sensing-based waveform (ESBW) strategy, by considering transmit waveform design as an active approach and cognitive loop for the time-varying environment. In ESBW strategy, OTH radar monitors the environment in real time, estimates interference characteristics, designs transmit waveform adaptively, and employs traditional signal processing structure to detect targets in the presence of interference. ESBW optimization problem employs the criteria of maximizing the output signal-to-interference-plus-noise ratio (SINR) of matched filter and similarity constraint for reasonable range resolution and sidelobe levels. The analytic solution to this constrained problem is developed, so that ESBW design algorithm's efficiency is guaranteed, with adjustable SINR and autocorrelation function. A simulated scenario with strong interference and colored noise has been introduced. Simulation results demonstrate that OTH radar with ESBW strategy detects the target successfully in the background of cochannel interference.

An effective scheme for radio frequency interference suppression in high-frequency radar

“…For the architecture of HF radar signal processing, the figure of merit for a discrete filter w is the SINR at the output of the envelope at the true target delay and Doppler shift [15]. Assuming negligible intra-pulse Doppler and no range gate straddling losses, filter design for optimizing the output SINR under similarity constraint is formulated as…”

“…Our previous work proposed a cognitive scheme of transmit signal design for cochannel interference suppression [15]. The designed signal is able to detect a target at the same incidence and Doppler of interference, based on training data sampled under radio silence.…”

Fast algorithm for designing periodic/aperiodic sequences with good correlation and stopband properties

“…Apart from the correlation property, the stopband property (which means suppressing several frequency bands) is usually considered in sequence design for suppressing narrowband interferences or avoiding the certain frequency bands that reserved for some applications, such as navigation and military communications [15][16][17][18][19]. Since the discontinuous frequency of the transmit waveform leads to high autocorrelation sidelobes, the correlation and stopband properties are both considered.…”

Optimal receive filter design under similarity constraint in coloured noise

“…Similarity constraint in the infinity norm is used to design phase code [5–7]. Similarity constraint in Euclidean norm is employed for robust receive beamforming [8], transmit waveform design based on the WF [9] or the MF [10], and joint design of transmit signal and receive filter for Doppler robustness [11]. The authors [9–11] optimise the output SNR under similarity constraint to control the output sequence envelope, for reasonable range resolution and peak sidelobe levels.…”

“…We also consider the comparison of five schemes, including the proposed MMF design, transmit signal design in [9, 10] and conventional signal with the MF/WF. We analyse their performances on the output SNR, sequence control and application requirements.…”