GPS-based space-surface passive bistatic radar technique for maritime moving target detection

Abstract

GNSS satellites as an illuminator and the receiver on the ground can construct a space-surface passive bistatic radar system for maritime moving target detection. However, the GNSS reflected signals from the maritime moving targets (such as vessels) are usually very weak and submerged by the background noise and the interference. To address this issue, a target detection method is proposed, which uses the peculiarity of the target's motion for echo energy concentration. First, because the trajectory of the moving vessel is considered as a synthetic aperture, SAR imaging technique-range-Doppler algorithm (RDA) is employed to concentrate the echo energy and suppress the interference such as sea clutter. Then, phase gradient autofocus (PGA) is exploited to perform autofocusing processing for further echo energy concentration. Multiple groups of real data are collected from the field trials to validate the proposed method. The experimental results show that the proposed method can concentrate the echo energy of multiple targets, estimate the target-to-receiver range accurately, and determine the target's moving direction. GNSS卫星作为一种照射源，可与地面接收机构成天-地无源双基地雷达系统，用于海面移动目标探测。但是，海面目标（如船只）反射的GNSS信号能量微弱，常被淹没在背景噪声和干扰信号中。针对这一问题，本文提出利用目标的运动特点聚集目标回波能量的目标探测方法。首先，将船只的运动轨迹看作合成孔径，采用SAR成像技术——距离多普勒算法（range-Doppler algorithm，RDA）实现目标回波能量的压缩聚集，同时抑制干扰信号（如海面杂波）。然后，使用相位梯度自聚焦算法（phase gradient autofocus，PGA）作自聚焦处理，进一步聚集目标回波能量。通过现场试验采集的数据验证了本文算法。试验结果表明，本文方法能够同时聚集多个目标回波能量，精确地估计目标到接收机的距离，并判断目标的移动方向。