volume | PIER Journals

Abstract

As we know, a moving target's azimuth shift in SAR image is proportional to the projected velocity of its across-track velocity in the slant-range plane. Therefore, we can relocate the moving target in SAR image after estimating its velocity. However, when Doppler ambiguity occurs due to the limitation of the SAR system's pulse repetition frequency (PRF), this relationship will not hold any more, in this case, we cannot relocate the moving target to the right position. The Doppler spectrum of a moving target with arbitrary velocity may entirely situate in a PRF band or spans in two neighboring PRF bands. In this paper, we conduct a detailed theoretical analysis on the moving target's azimuth shift for these two scenarios. According to the derived formulas, one can relocate a moving target with arbitrary velocity to the right position no matter Doppler ambiguity occurs or not. Simulated data are processed to validate the analysis.

1. Cumming, I. G. and F. H. Wong, Digital Signal Processing of Synthetic Aperture Radar Data: Algorithms and Implementation, Artech House, 2005.

2. Jao, J. K., "Theory of synthetic aperture radar imaging of a moving target," IEEE Transactions on Geoscience and Remote Sensing, Vol. 39, No. 9, 1984-1992, 2001.
doi:10.1109/36.951089

3. Zhang, Y., W. Zhai, X. Zhang, X. Shi, X. Gu, and Y. Deng, "Ground moving train imaging by Ku-band radar with two receiving channels," Progress In Electromagnetics Research, Vol. 130, 493-512, 2012.
doi:10.2528/PIER12060201

4. Yang, J., C. Liu, and Y. F. Wang, "Imaging and parameter estimation of fast-moving targets with single-antenna SAR," IEEE Geoscience and Remote Sensing Letters, Vol. 11, No. 2, 529-533, 2014.
doi:10.1109/LGRS.2013.2271691

5. Yang, J., C. Liu, and Y. F. Wang, "Detection and imaging of ground moving targets with real SAR data," IEEE Transactions on Geoscience and Remote Sensing, Vol. 53, No. 2, 920-932, 2015.
doi:10.1109/TGRS.2014.2330456

6. Mao, X., D.-Y. Zhu, and Z.-D. Zhu, "Signatures of moving target in polar format spotlight SAR image," Progress In Electromagnetics Research, Vol. 92, 47-64, 2009.
doi:10.2528/PIER09030908

7. Zhang, Y., X. Shi, X. Gu, W. Zhai, X. Kang, Y. Deng, D. Li, X. Dong, J. Yang, Q. Yang, Q. Yang, Y. Tang, X. Zhang, and J. Jiang, "Introduction to the researches on radar conducted in MIRSL/CAS," PIERS Proceedings, 454-460, Guangzhou, Aug. 25-28, 2014.

8. Chiu, S. and C. Livingstone, "A comparison of displaced phase centre antenna and along-track interferometry techniques for RADARSAT-2 ground moving target indication," Canadian Journal of Remote Sensing, Vol. 31, 37-51, 2005.
doi:10.5589/m04-052

9. Cerutti-Maori, D. and I. Sikaneta, "A generalization of DPCA processing for multichannel SAR/GMTI radars," IEEE Transactions on Geoscience and Remote Sensing, Vol. 51, No. 1, 560-572, 2013.
doi:10.1109/TGRS.2012.2201260

10. Moccia, A. and G. Rufino, "Spaceborne along-track SAR interferometry: Performance analysis and mission scenarios," IEEE Transactions on Aerospace and Electronic Systems, Vol. 37, No. 1, 199-213, 2001.
doi:10.1109/7.913679

11. Romeiser, R., H. Breit, M. Eineder, and H. Runge, "Demonstration of current measurements from space by along-track SAR interferometry with SRTM data," 2002 IEEE International Geoscience and Remote Sensing Symposium, 2002.

12. Budillon, A., A. Evangelista, and G. Schirinzi, "GLRT detection of moving targets via multibaseline along-track interferometric SAR systems," IEEE Geoscience and Remote Sensing Letters, Vol. 9, No. 3, 348-352, 2012.
doi:10.1109/LGRS.2011.2168381

13. Tian, B., D.-Y. Zhu, and Z.-D. Zhu, "A novel moving target detection approach for dual-channel SAR system," Progress In Electromagnetics Research, Vol. 115, 191-206, 2011.
doi:10.2528/PIER10120107

14. Dipietro, R. C., "Extended factor space-time processing for airborne radar system," The Twenty-Sixth Asilomar Conference on Signals, Systems and Computers, 1992.

15. Chen, H. C. and C. D. McGillem, "Target motion compensation by spectrum shifting in synthetic aperture radar," IEEE Transactions on Aerospace and Electronic Systems, Vol. 28, No. 3, 895-901, 1992.
doi:10.1109/7.256313

16. Moreira, J. R. and W. Keydel, "A new MTI-SAR approach using the reflectivity displacement method," IEEE Transactions on Geoscience and Remote Sensing, Vol. 33, No. 5, 1238-1244, 1995.
doi:10.1109/36.469488

17. Lv, G., J. Wang, and X. Liu, "Ground moving target indication in SAR images by symmetric defocusing," IEEE Geoscience and Remote Sensing Letters, Vol. 10, No. 2, 241-245, 2013.
doi:10.1109/LGRS.2012.2200232

18. Perry, R. P., R. C. DiPietro, and R. L. Fante, "SAR imaging of moving targets," IEEE Transactions on Aerospace and Electronic Systems, Vol. 35, No. 1, 188-200, 1999.
doi:10.1109/7.745691

19. Zhou, F., R. Wu, M. Xing, and Z. Bao, "Approach for single channel SAR ground moving target imaging and motion parameter estimation," IET Radar Sonar and Navigation, Vol. 1, No. 1, 59-66, 2007.
doi:10.1049/iet-rsn:20060040

20. Zhu, D., Y. Li, and Z. Zhu, "A keystone transform without interpolation for SAR ground moving-target imaging," IEEE Geoscience and Remote Sensing Letters, Vol. 4, No. 1, 18-22, 2007.
doi:10.1109/LGRS.2006.882147

21. Li, G., X. G. Xia, and Y. N. Peng, "Doppler keystone transform: an approach suitable for parallel implementation of SAR moving target imaging," IEEE Geoscience and Remote Sensing Letters, Vol. 5, No. 4, 573-577, 2008.
doi:10.1109/LGRS.2008.2000621

22. Yang, J. F. and Y. H. Zhang, "Novel compressive sensing-based Dechirp-Keystone algorithm for synthetic aperture radar imaging of moving target," IET Radar Sonar and Navigation, Vol. 9, No. 5, 509-518, 2015.
doi:10.1049/iet-rsn.2014.0306

23. Yang, J. and Y. Zhang, "A novel Keystone transform based algorithm for moving target imaging with Radon transform and fractional Fourier transform involved," PIERS Proceedings, 1406-1410, Guangzhou, Aug. 25-28, 2014.

24. Kong, Y. K., B. L. Cho, and Y. S. Kim, "Ambiguity-free Doppler centroid estimation technique for airborne SAR using the Radon transform," IEEE Transactions on Geoscience and Remote Sensing, Vol. 43, No. 4, 715-721, 2005.
doi:10.1109/TGRS.2005.843955

25. Cumming, I. G. and S. Li, "Improved slope estimation for SAR Doppler ambiguity resolution," IEEE Transactions on Geoscience and Remote Sensing, Vol. 44, No. 3, 707-718, 2006.
doi:10.1109/TGRS.2005.861925

26. Zhu, S., G. Liao, B. Liu, and Y. Qu, "New approach for SAR Doppler ambiguity resolution in compressed range time and scaled azimuth time domain," IEEE Transactions on Aerospace and Electronic Systems, Vol. 47, No. 4, 3026-3039, 2011.
doi:10.1109/TAES.2011.6034686

27. Barbarossa, S. and A. Farina, "Detection and imaging of moving objects with synthetic aperture radar. Part 2: Joint time-frequency analysis by Wigner-Ville distribution," IEE Radar and Signal Processing, 89-97, 1992.
doi:10.1049/ip-f-2.1992.0011

28. Sun, H., G. S. Liu, H. Gu, and W. M. Su, "Application of the fractional Fourier transform to moving target detection in airborne SAR," IEEE Transactions on Aerospace and Electronic Systems, Vol. 38, No. 4, 1416-1424, 2002.
doi:10.1109/TAES.2002.1145767

29. Djurovic, I., T. Thayaparan, and L. J. Stankovic, "SAR imaging of moving targets using polynomial Fourier transform," IET Signal Processing, Vol. 2, 237-246, 2008.
doi:10.1049/iet-spr:20070114

30. Zhang, X. P., G. S. Liao, S. Q. Zhu, C. Zeng, and Y. X. Shu, "Geometry-information-aided efficient radial velocity estimation for moving target imaging and location based on Radon transform," IEEE Transactions on Geoscience and Remote Sensing, Vol. 53, No. 2, 1105-1117, 2015.
doi:10.1109/TGRS.2014.2334322

31. Zhu, S. Q., G. S. Liao, Y. Qu, Z. G. Zhou, and X. Y. Liu, "Ground moving targets imaging algorithm for synthetic aperture radar," IEEE Transactions on Geoscience and Remote Sensing, Vol. 49, No. 1, 462-477, 2011.
doi:10.1109/TGRS.2010.2053848

32. Sun, G. C., M. D. Xing, X. G. Xia, Y. R. Wu, and Z. Bao, "Robust ground moving-target imaging using Deramp-Keystone processing," IEEE Transactions on Geoscience and Remote Sensing, Vol. 51, No. 2, 966-982, 2013.
doi:10.1109/TGRS.2012.2204889

Dr. Jiefang Yang

Prof. Yunhua Zhang