In many radar tracking systems ·with a certain pulse-repetition frequency (PRF), Doppler (or range rate) measurements are available in addition to position measurements. The extra range rate information Doppler measurements provide is able to improve the tracking performance. However, a fundamental problem associated with Pulse-Doppler radars is, especially at low PRFs, range rate ambiguity. This is because Doppler shifts in the frequency spectrum are aliased by a difference of an integer times of PRF. In this case, the observed Doppler measurement shifts from the true range rate by an unknown difference.
In previous works, algorithms to eliminate the Doppler ambiguity based on the Chinese Remainder Theorem have been proposed for radars with multiple PRFs. Time- Frequency Analysis (TFA) using Fast Fourier Transform (FFT) can reduce the ambiguity in the frequency domain.
In this paper, a new approach for multitarget detection and tracking with Doppler ambiguity is presented. Ambiguous Doppler measurements in addition to the position measurements are directly used in data association and tracking. To solve the Doppler ambiguity for single target tracking, three methods are proposed based on UKF, MHT and PDA, respectively. In addition, modifications to Multiple Hypothesis Tracking (MHT) and Joint Integrated Probabilistic Data Association (JIPDA) algorithms to resolve Doppler ambiguity in multitarget tracking are considered. Simulation results are preformed to demonstrate the new algorithms with tracking results analysis.