Doppler ambiguity resolution using optimal multiple pulse repetition frequencies

Ferrari, Berenguer, and Alengrin (ibid., vol. 33, pp. 738-51, 1997) proposed an algorithm for velocity ambiguity resolution in coherent pulsed Doppler radar using multiple pulse repetition frequencies (PRFs). In this algorithm, two step estimations (folded frequency and ambiguity order) for the Doppler frequency is used by choosing particular PRF values. The folded frequency is the fractional part of the Doppler frequency and is estimated by averaging the folded frequency estimates for each PRF. The ambiguity order is the integer part of the Doppler frequency and is estimated by using the quasi-maximum-likelihood criterion. The PRF are grouped into pairs and each pair PRF values are symmetric about 1. The folded frequency estimate for each pair is the circular mean of the two folded frequency estimates of the pair due to the symmetry property. We propose a new algorithm based on the optimal choice of the PRF values, where the PRF values are also grouped into pairs. In each pair PRF values, one is given and the other is optimally chosen. The optimality is built upon the minimal sidelobes of the maximum likelihood criterion. Numerical simulations are presented to illustrate the improved performance.