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.
2. Melvin, W. L. and J. A. Scheer (Eds.), Principles of Modern Radars --- Vol. III, Radar Applications, IET/SciTech Publishing, Raleigh, NC, 2012.
3. Skolnik, M. I., Introduction to Radar Systems, 2nd Ed., McGraw Hill, New York, 1981.
4. Skolnik, M. I., Radar Handbook, 2nd Ed., 1990.
5. Skolnik, M. I., Radar Handbook, 3rd Ed., 2008.
6. Trunk, G. V. and M. W. Kim, "Ambiguity resolution of multiple targets using pulse-Doppler waveforms," IEEE Transactions on Aerospace and Electronic Systems, Vol. 30, No. 4, 1130-1137, Oct. 1994.
doi:10.1109/7.328789
7. Chuan, Y. K., M. K. Loke, R. C. Shui, and L. F. Chen, Ducting phenomena and their impact on a pulse Doppler radar, 88-99, DSTA Horizons, 2010, https://www.dsta.gov.sg/docs/publicationsdocuments/ducting-phenomena-and-their-impact-on-a-pulse-doppler-radar.pdf?sfvrsn=0.
8. US Patent 6,081,221, Dusan S. Zrnic and Mangalore Sachidananda, , 2000.
9. US Patent 5,079,556, Shin-Ichi Itoh, , 1992.
10. Levanon, N., "Mitigating range ambiguity in high PRF radar using inter-pulse binary coding," IEEE Transactions on Aerospace and Electronic Systems, Vol. 45, No. 2, 687-697, Apr. 2009.
doi:10.1109/TAES.2009.5089550
11. Anderson, J., M. Temple, W. Brown, and B. Crossley, "A nonlinear suppression technique for range ambiguity resolution in pulse Doppler radars," Proceedings of the 2001 IEEE Radar Conference, 141-146, Atlanta, USA, 2001.
12. Anderson, J., Nonlinear suppression of range ambiguity in pulse Doppler radar, Dissertation, AFIT/DS/ENG/01-05, Air Force Institute of Technology, Graduate School of Engineering and Management, Dec. 13, 2001.
13. Levanon, N. and E. Mozeson, Radar Signals, Wiley, 2004.
doi:10.1002/0471663085
14. Tyler, S. and R. Kesten, Optimal Periodic Binary Codes of Lengths 28 to 64, TDA Progress Report 42–57, Mar. and Apr. 1980, Jet Propulsion Laboratory, Pasadena, CA.