A Modified Sequential Multiplexed Method for Detecting Airborne and Sea Targets With Over-the-Horizon Radar

Phased array over-the-horizon (OTH) radar usually needs to detect sea target and airborne target in different directions. Conventionally, the sea target and airborne target are detected sequentially with the coherent integration completely accomplished for each of them. However, the long coherent integration time (CIT) required by the sea target makes the time interval between two airborne target detections too long, which is not conducive to tracking airborne target. To overcome this problem, this paper proposes a new timeframe multiplexing scheme, in which several short-time detections of airborne target are inserted into a long CIT of sea target detection. The proposed scheme seeks to improve the detection frequency of airborne target while ensuring the detection performance of two types of target. However, due to the insertion of airborne target detection, the echo from sea surface is received discontinuously which means that the coherent integration of sea target is incomplete. To tackle it, a recovery algorithm based on the Hankel structured matrix is introduced, which recovers the slow-time domain signal of each range bin and thereby guarantees the detection performance of sea target not damaged. Numerical simulations prove the effectiveness of the proposed algorithm for signal recovery, and also verify that the proposed operating scheme has a shorter time interval for airborne target detection, while the detection performance of two targets are well guaranteed.