Efficient elimination of multiple-time-around detections in pulse-doppler radar systems

The paper introduces a new method for eliminating multiple-time-around detections in coherent pulsed radar systems with single constant pulse repetition frequency. The method includes the phase modulation of transmit pulses and corresponding phase demodulation at reception, which is matched to signals from the unambiguous range interval, and subsequent coherent integration followed by successive CFAR processing in range and Doppler domains. The performance of the proposed method is studied by means of statistical simulations. It is shown that the elimination performance can be essentially improved by optimizing the transmit phase modulation code. The optimization problem is formulated in terms of least-square fitting the power spectra of multiple-time-around target signals to a uniform power spectrum. Several optimum biphase codes are designed and used in the performance analysis. The analysis shows that the method can provide very high probability of elimination without noticeable degradation in the detection performance for targets from the unambiguous range interval.