Feifei Yan

Rapid raw data simulation for fixed-receiver bistatic interferometric synthetic aperture radar

Abstract. Raw data simulation of synthetic aperture radar (SAR) is useful for system designing, mission planning, and testing of imaging algorithms. According to the two-dimensional (2-D) frequency spectrum of the fixed-receiver bistatic SAR system, a rapid raw data simulation approach is proposed. With the combination of 2-D inverse Stolt transform in the 2-D frequency domain and phase compensation in the range-Doppler frequency domain, our approach can significantly reduce the simulation time. Therefore, simulations of extended scenes can be performed much more easily. Moreover, the proposed algorithm offers high accuracy of phase distribution, therefore, it can be used for single-pass fixed-receiver bistatic interferometric usage. The proposal is verified by extensive simulations of point targets and extended scene, in which the results indicate the feasibility as well as the effectiveness of our approach. In the end, the accuracy of phase distribution of the proposed algorithm is further examined with simulations of synthetic aperture radar interferometry.

Analysis and Validation of Transmitter's Beam Footprint Detection and Tracking for Noncooperative Bistatic SAR

In noncooperative bistatic synthetic aperture radar (SAR), the position of the transmitters beam footprint should be detected and tracked in real time to perform beam synchronization. Theoretical analysis shows that the signal-to-noise ratio (SNR) of the reflected signals from the observational scene is too low to apply the conventional detection and tracking method. According to the cross correlation and Doppler frequency information of the raw data, a transmitters beam footprint detection and tracking method is proposed in this paper. This method can realize the beam footprint detection in the sidelobe of the receivers beam footprint and obtain the relative position between the transmitter and the receiver, therefore significantly improve the performance of beam footprint detection and tracking in noncooperative. Meanwhile, vehicle-based bistatic SAR experiment and airborne bistatic SAR experiment are performed to evaluate the performance of the proposed transmitters beam footprint detection and tracking method. Experimental results show that the proposed method performs well for real-time transmitters beam footprint detection and tracking.

Equivalent validation of beam footprint detection for non-cooperative bistatic SAR

In non-cooperative bistatic synthetic aperture radar (SAR), the position of transmitters beam footprint should be detected in real-time to perform beam synchronization. Theoretical analysis shows that signal-to-noise ratio (SNR) of the reflected echoes from the observed scene is too low to use the conventional detect method. According to the cross-correlation between the echoes of adjacent pulse repetition frequency (PRF) and M-out-of-N (M/N) detection, a reflected echo detect method is proposed in this paper. This method can realize the accumulation of signal energy and enormously improve the performance of beam footprint detection. Mean-while, vehicle-based equivalent validation experiment is performed. Experiment results show that the proposed method can be well used for real-time transmitters beam footprint detection.

Beam Footprint Detection and Tracking for Non-cooperative Bistatic SAR

In non-cooperative bistatic synthetic aperture radar (SAR), the position of transmitter’s beam footprint should be detected and tracked in real-time to perform beam synchronization. Theoretical analysis shows that signal-tonoise ratio (SNR) of the reflected echoes from the observational scene is too low to apply the conventional detection and tracking method. According to the cross-correlation and Doppler frequency information of the backscattering echo, a beam footprint detection and tracking method is proposed in this paper. This method can realize accumulation of signal energy, therefore enormously improve the performance of beam footprint detection and tracking. Meanwhile, vehiclebased bistatic SAR experiment and airborne bistatic SAR experiment are performed to evaluate the performance of the proposed beam footprint detection and tracking method. Experimental results show that the proposed method performs well for real-time transmitter beam footprint detection and tracking.

SLIDING SPOTLIGHT BISTATIC SYNTHETIC APERTURE RADAR IMAGE FORMATION ALGORITHM BASED ON DIRECT-PATH SIGNAL COMPENSATION

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-to-noise 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 direct-path 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, direct-path 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.

Efficient simulation for fixed-receiver bistatic SAR with time and frequency synchronization errors

Raw signal simulation is a useful tool for synthetic aperture radar (SAR) system design, mission planning, processing algorithm testing, and inversion algorithm design. Time and frequency synchronization is the key technique of bistatic SAR (BiSAR) system, and raw data simulation is an effective tool for verifying the time and frequency synchronization techniques. According to the two-dimensional (2-D) frequency spectrum of fixed-receiver BiSAR, a rapid raw data simulation approach with time and frequency synchronization errors is proposed in this paper. Through 2-D inverse Stolt transform in 2-D frequency domain and phase compensation in range-Doppler frequency domain, this method can significantly improve the efficiency of scene raw data simulation. Simulation results of point targets and extended scene are presented to validate the feasibility and efficiency of the proposed simulation approach.