Xiong Jintao

Research on A novel fast backprojection algorithm for stripmap bistatic SAR imaging

In this paper, a novel fast backprojection (BP) algorithm for stripmap bistatic SAR is presented. This algorithm gets improvements from the perspective of beam form and the space relation between the flight path and the mapping areas. Comparing with the traditional BP algorithm, the fast BP algorithm has higher computational efficiency. Also, it keeps the advantages of the traditional BP algorithm, such as robustness, high imaging precision, small memory requirements in processor and parallel processing easily. The imaging results of point targets and the experimental data verify the advantages of the fast BP algorithm.

Synchronization Technology of Bistatic Radar System

A complete method of synchronization technology of bistatic radar using global position system (GPS) is presented. The time benchmark signal 1PPS was elaborately modified in order to increase the time synchronization precision. A very high time synchronization precision was achieved. Using the modified 1PPS to discipline the local VCXO, the reference frequency signal both achieve a high long term stability (LTS) and short term stability (STS) property. The experimental results show that the time synchronization precision of our synchronization system can be improved from plusmn100 ns to plusmn25 ns. Well, the STS reach 2times10-11/s and the phase noise is improved 20 dB comparing with the results

SAR Doppler frequency rate estimation based on time-frequency rate distribution

Time-frequency rate distribution (TFRD) indicates the characteristics of instantaneous frequency rate (IFR) of a signal. This paper proposed a method based on time-frequency rate distribution to estimate Doppler frequency rate by analyzing the linear frequency-modulated (LFM) characteristics of synthetic aperture radar (SAR) echo in the azimuth direction. This method can be applied to low signal-to-noise ratio (SNR) situation with high estimation precision. Simulation and practical results show the effectiveness of the method.

Research on airborne bistatic SAR squint imaging mode algorithm and experiment data processing

The parallel flight squint mode of airborne bistatic synthetic aperture radar (SAR) is discussed in this paper. The bistatic squint imaging mode (SIM) algorithm is used to solve the coupling between the range and the azimuth of this mode. Simulation results prove the availability of this algorithm. The bistatic SIM algorithm is also used to process the experiment data, and a well focused Bistatic SAR image is generated successfully. Comparing the generated image with the bistatic rang-Doppler (RD) algorithm, we can find that the result of bistatic SIM algorithm is much better than that of bistatic RD algorithm in the parallel flight squint mode.

Precise time frequency synchronization technology for bistatic radar

Abstract A complete method of synchronization technology of bistatic radar using global position system (GPS) is presented. The pulse per second signal (1PPS) is elaborately modified to increase the time synchronization precision and keep loop locking. A very high time synchronization precision is achieved. Using the modified 1PPS to discipline the local OCXO, the reference frequency signal achieves both high long term stability (LTS) and short term stability (STS) properties. An algorithm, named phase abrupt change CFAR is presented to restrain the 1PPS phase abrupt change and keep loop locking. The experimental results indicate that this time and frequency synchronization method is effective and the time synchronization precision of the synchronization system can be improved from ± 100 ns to ± 25 ns. In addition, the phase noise is improved to 20 dB.

Analysis of Bistatic SAR Frequencey Synchronization

In this paper, a bistatic SAR echos mathematical expression with frequency errors is given, and the frequency error was analysed. Two types of frequency synchronization errors were considered. We analysed the different effects about imaging of bistatic SAR in the condition that the echo with different frequency errors. The analytical result is proved by simulation, it can be the reference for bistatic SAR system design

Novel method for ambiguity elimination in the LFMCW radar

Abstract Aimed at solving the distance and velocity decoupling problems of a moving target in LFMCW radar signal processing, a multiple repetition frequency waveform is adopted and a Doppler frequency duster algorithm is proposed, which is capable of recovering true velocity from the coupled velocity estimation directly. For the resolution of multiple targets, a match algorithm based on mean square error is also proposed. The combination of the above two methods realizes distance and velocity decoupling of multiple moving targets. The result of simulation verifies the effectiveness of the methods, the velocity estimation performance of DFS algorithm is improved by 2.5 dB compared with Chinese remainder theorem.