A Heuristic Forward Scatter Radar Detector for Sky Fence with Opportunistic Signals from LEO Satellites

Traditionally, the crystal video detector (CVD) has been used in a forward scatter (FS) radar to detect a moving target, with the requirement that some parameters of the target, such as its shape and locations, are available a priori . This work introduces a simple heuristic detector based on the variance changes in received signal amplitudes, eliminating the need for target parameters. The proposed detector is suitable for ground-based FS radars using opportunistic signals from broadband low Earth orbit (LEO) satellite communication systems, particularly for unmanned aerial vehicle (UAV) detection in a "sky fence" setup. Theoretical analysis of the receiver operating characteristics (ROC) indicates that although the CVD generally outperforms the heuristic detector, the performance gap is minimal with relatively small target-induced Doppler shifts compared with the signal bandwidth of the satellite communication system. Both detectors are effective for small target detection within the narrow beamwidth of antennas used in broadband LEO satellite communications. The proposed detector’s application in a simplistic sky fence scenario demonstrates its potential for UAV detection.