Resolution of range and Doppler ambiguities in medium PRF radars in multiple target environment

Abstract In medium pulse-repetition frequency (PRF) radars, ambiguities may arise in both range and Doppler measurements. Efficient techniques have been established (Skolnik, 1970; Hovanessian, 1976) to resolve the range ambiguity of a single isolated target using multiple PRFs. In this paper, we propose a simple algorithm to resolve the Doppler ambiguity using the discrete Fourier transform (DFT) output of two PRFs. A condition on the relative values of the two PRFs is derived to account for the errors due to the finite bandwidths of DFT filters. Next, we describe a method to resolve both Doppler and range ambiguities in a multiple-target environment. The method uses three PRFs to resolve Doppler ambiguities and to identify the declarations of a particular target in different PRFs. Range ambiguities are then resolved in a straightforward manner. A fourth PRF is made use of to extract blind-speed targets. The proposed method is computationally efficient and can be used even when ambiguous returns from several targets are received. Implementation trade-offs are also discussed.