A Scheme for Multitarget Lateral Velocity Measurement With High-Frequency Monostatic Radar

This paper proposes a method for extracting the lateral velocity in multitarget cases to improve the ship tracking capability of high-frequency surface wave radar (HFSWR). The method exploits the phase interferometry between two antenna arrays that is done in the time domain after joint frequency-azimuth filtering. First, a frequency filter based on generalized S transform with a variable factor is applied to eliminate the background noise. The variable factor is linked to the target's radial velocity and can control the time and frequency resolutions. We then use two identical subarrays as two receiving channels to implement the azimuth filtering. Based on adaptive minimum-variance distortionless response beamforming, the extraneous signals can be suppressed. Subsequently, the varying slope of the phase difference of the target of interest signal from two channels can be extracted to compute the lateral velocity in a low signal-to-noise ratio scenario. The interference of noise and extraneous target signals is analyzed using simulations, and the effectiveness of the frequency-azimuth filtering method is validated with both simulations and experimental data. In addition, the high spatial resolution ship tracking results over an hour match well with automatic identification system data, demonstrating the feasibility of tracking targets with HF monostatic radar.