In fixed-receiver bistatic synthetic aperture radar (SAR), the spaceborne SAR is used as an illuminator. The direct-path signal and bistatic SAR raw data are sampled by the fixed-receiver which is placed on the top of a building or a hill. As the direct-path signal has high signal-tonoise ratio (SNR) advantage and almost the same synchronization error terms, it is used as the reference signal for the range matched filtering. Then the range compression can be realized with a time and frequency synchronization process. However, after range match filtering by the directpath signal, the range history of point target consists of three square-root terms, for which it is hard to use the Principle of Stationary Phase (POSP). Meanwhile, the two-dimensional (2-D) spatial variation of the target's 2-D frequency spectrum is serious. By combining azimuth preprocessing, directpath signal compensation and nonlinear Chirp Scaling (NLCS) imaging algorithm, a new focusing algorithm is presented in this paper. Simulation results of point targets are presented to validate the efficiency and feasibility of the proposed imaging algorithm. Finally, this algorithm is also validated by the measured data which is obtained using the HITCHHIKER system.
2. Behner, F., S. Reuter, and H. Nies, "Synchronization and preprocessing of hybrid bistatic SAR data in the HITCHHIKER experiment," European Conference on Synthetic Aperture Radar, 268-271, Berlin, Germany, Jun. 2014.
3. Zhou, F., G. C, Sun, and M. D. Xin, "A full-aperture imaging algorithm for hybrid sliding spotlight bistatic SAR," IET International Radar Conference, 1-5, Xi'an, China, Oct. 2013.
4. Wang, R., Y. K. Deng, and O. Loffeld, "Processing the azimuth-variant bistatic SAR data by using monostatic imaging algorithms based on two-dimensional principle of stationary phase," IEEE Trans. Geosci. Remote Sens., Vol. 49, No. 4, 3504-3520, 2011.
5. Zhou, P., Y. M. Chen, W. F. Sun, and Y. Wan, "Efficient imaging approach for spaceborne sliding spotlight synthetic aperture radar with a small squint angle," Journal of Applied Remote Sensing, Vol. 9, No. 3, 1-13, 2015.
6. Yan, F. F., W. G. Chang, and X. Y. Li, "Efficient simulation for fixed-receiver bistatic SAR with time and frequency synchronization errors," Radio Engineering, Vol. 24, No. 4, 917-926, 2015.
7. Neo, Y. L., F. G. Wong, and I. G. Cumming, "Processing of azimuth-invariant bistatic SAR data using the range Doppler algorithm," IEEE Trans. Geosci. Remote Sens., Vol. 46, No. 1, 14-21, 2008.
8. Dekker, P. L., J. J. Mallorqui, P. S. Morales, and J. S. Marcos, "Phase synchronization and Doppler centroid estimation in fixed receiver bistatic SAR systems," IEEE Trans. Geosci. Remote Sens., Vol. 46, No. 11, 3459-3471, 2008.
9. Krieger, G. and M. Younis, "Impact of oscillator noise in bistatic and multistatic SAR," IEEE Geosci. Remote Sens. Lett., Vol. 3, No. 3, 424-428, 2006.
10. Sun, G. C., M. D. Xing, Y.Wang, and Y. F.Wu, "Sliding spotlight and TOPS SAR data processing without subaperture," IEEE Geosci. Remote Sens. Lett., Vol. 8, No. 6, 1036-1040, 2006.
11. Zhang, Q. L., W. G. Chang, and X. Y. Li, "An extended NLCS algorithm for bistatic fixed-receiver SAR imaging," European Radar Conference, 1-5, Paris, France, Oct. 2013.
12. Wong, F. H. and T. S. Yeo, "New applications of nonlinear chirp scaling in SAR data processing," IEEE Trans. Geosci. Remote Sens., Vol. 39, No. 5, 946-953, 2001.
13. Tian, W. M., T. Long, J. Yang, and X. P. Yang, "Combined analysis of time and frequency synchronization errors for BiSAR," CIE International Conference on Radar, 388-392, Chengdu, China, Nov. 2011.