Track-before-detect strategies for Multiple-PRF Radar System with Range and Doppler Ambiguities

Medium pulse repetition frequency (MPRF) radar system is widely applied in practice since it combines the desirable features of both low and high PRF radars. However, the corresponding signal processing is more complicated due to range and Doppler ambiguities. N staggered PRFs are designed in the system with the intention of being able to solve ambiguities. Traditional target tracking method solves ambiguities initially by performing ambiguity resolutions over thresholded measurements, while it has a poor performance when target signal-to-noise ratio (SNR) is low. Multi-frame track-before-detect (MF-TBD) is an advantageous method to track dim targets. Unfortunately, it fails to be applied in multiple-PRF radar system directly as the target state space and the measurement space is not the one-to-one correspondence, which results in the increased complexity of the algorithm. In this paper, TBD strategies for multiple-PRF radar system with range and Doppler ambiguities are proposed to solve those issues. A set of new measurements (real measurements combined in a different manner) are firstly synthesized according to different PRF data. Then a cross-boundary search criterion of TBD designed for ambiguous measurements is applied over the N sets of new measurements, producing the ambiguous plot-sequences. Finally, the joint disambiguation is proposed to obtain unambiguous plot-sequences. Simulations show that the proposed method significantly outperforms the classical ambiguity resolution Kalman filter (CAR-KF) algorithm.