New method for unambiguous velocity measurement in low PRT radar

Low pulse repetition frequency (PRF) radars are mainly used for target tracking and measurement of distance and angle. Because the pulse repetition frequency is very low and there is serious ambiguity in radial velocity measurement, many common methods can not resolve the ambiguity effectively. Based on the velocity measurement system which includes the digital intermediate frequency locked loop (DIFLL) and spectrum peak search (SPS), a changeable step search method is put forward to resolve the ambiguity, and the symmetrical coefficient is used to judge the spectrum peak. In the result, the anti-noise performance is improved by nearly 24 dB and the speed of ambiguity resolution is greatly increased. The simulation results prove that this method is available and has high practicable value.