A Co-Channel Signal Detector Based on Phase Tracking for Pulse Doppler Radar

Doppler processing is routinely applied to isolate targets from noise, clutter and interference in conventional pulse-Doppler radar. If a target is co-located in range and azimuth and has a similar radial velocity (co-channel) as another target (or interference), that target may not be detected. This is because only amplitude or power information is used in the detection stage, which does not provide sufficient information to discriminate co-channel signals from each other. In this paper we propose a detector which can resolve co-located targets (or target with interference) with similar Doppler frequencies. Instead of only using phase information for the coherent integration, our proposed detector tracks the phase modulation differences of the co-located, co-channel, targets. The amplitude information of the targets can also be estimated and forwarded to the tracker. One application of this method is HF radar where a target may have a Doppler frequency similar to a Bragg line - first order sea clutter. The Bragg lines are generally dominant at all ranges and exist in all directions. Conventional processing fails to discriminate when targets radar features are similar to the Bragg lines. Simulations of the proposed method show promising results that targets with Doppler frequencies near Bragg lines can be detected.