A Novel Algorithm for Doppler Frequency Rate Estimation of Spaceborne Synthetic Aperture Radar

2006 ◽  
pp. 144-149
Author(s):  
Shiqi Huang ◽  
Daizhi Liu ◽  
Liang Chen ◽  
Yunfeng Liu
Keyword(s):  
Synthetic Aperture Radar ◽  
Doppler Frequency ◽  
Synthetic Aperture ◽  
Rate Estimation ◽  
Frequency Rate ◽  
Novel Algorithm ◽  
Aperture Radar

Analysis of Forward-Looking Synthetic Aperture Radar Imaging Characteristics of Rotating Target

2014 ◽  
Vol 1044-1045 ◽  
pp. 1057-1060
Author(s):  
Lei Chen ◽  
Dian Ren Chen ◽  
Ying Liu ◽  
Ze Chuan Lv
Keyword(s):  
Synthetic Aperture Radar ◽  
Doppler Frequency ◽  
Synthetic Aperture ◽  
Stationary Target ◽  
Imaging Result ◽  
Imaging Characteristics ◽  
Imaging Results ◽  
Rotating Target ◽  
Aperture Radar ◽  
Forward Looking

In this paper,it is established the geometric and radar echo model of the rotating target with the Forward-looking synthetic aperture radar firstly,then the Doppler frequency History Formula is Deduced and Pointed out that the Formula has a sinusoidal characteristics. It is simulated the imaging of the stationary target and the rotating target with different rotation speed, the imaging result can be expressed as the forms of curve and the curve circle nomadic type, when these features appear in the imaging results, it can initially determine that the rotating target is presence.

Parameter Estimation of Spaceborne SAR Based on the Combination of STFT and FRFT

2010 ◽  
Vol 20-23 ◽  
pp. 954-957
Author(s):  
Jin Liang Bai ◽  
Rong Gang Wu ◽  
Jun Ling Wang ◽  
Yong Bin Hong
Keyword(s):  
Parameter Estimation ◽  
Computational Complexity ◽  
Synthetic Aperture Radar ◽  
Parameters Estimation ◽  
Synthetic Aperture ◽  
Direct Estimation ◽  
Frequency Rate ◽  
Transmitted Signal ◽  
Simulation Results ◽  
Aperture Radar

A method of parameters estimation of spaceborne synthetic aperture radar based on combination algorithm of STFT and FRFT is proposed in this paper. Parameters here namely frequency centroid and frequency rate characterize the transmitted signal of spaceborne SAR. Estimation the parameters of the single way SAR signal is very important in ESM system. The combination algorithm of STFT and FRFT proposed in this paper overcomes the inaccuracy of direct estimation by STFT and large computation burden of pure FRFT. Simulation results show that this method is feasible and effective in improving the accuracy and reducing computational complexity for parameters estimation of spaceborne SAR.

scholarly journals A Fast Bistatic ISAR Imaging Approach for Rapidly Spinning Targets via Exploiting SAR Technique

2020 ◽  
Vol 12 (13) ◽  
pp. 2077
Author(s):  
Zhijun Yang ◽  
Dong Li ◽  
Xiaoheng Tan ◽  
Hongqing Liu ◽  
Guisheng Liao
Keyword(s):  
Synthetic Aperture Radar ◽  
Signal To Noise Ratio ◽  
Doppler Frequency ◽  
Synthetic Aperture ◽  
Coherent Integration ◽  
Range Cell ◽  
Isar Imaging ◽  
Imaging Approach ◽  
Spinning Targets ◽  
Aperture Radar

Because of the large range of cell migration (RCM) and nonstationary Doppler frequency modulation (DFM) produced by non-cooperative targets with rapid spinning motions, it is difficult to efficiently generate a well-focused bistatic inverse synthetic aperture radar (ISAR) by use of the conventional imaging algorithms. Utilizing the property of the inherent azimuth spatial invariance in strip-map synthetic aperture radar (SAR) imaging mode, in this work, an efficient bistatic ISAR imaging approach based on circular shift operation in the range-Doppler (RD) domain is proposed. First, echoes of rapidly spinning targets are transformed into the RD domain, whose exact analytical is derived on the basis of the principle of stationary phase (POSP). Second, the RCM is corrected by using an efficient circular shift operation in the RD domain. By doing so, the energies of a scatterer that span multiple range cells are concentrated into the same range cell, and the time-varying DFM can also be compensated along the rotating radius direction. Compared with existing methods, the proposed method has advantages in its computational complexity, avoiding the interpolation and multi-dimensional search operation, and in its satisfactory imaging performance under low signal to noise ratio (SNR) conditions thanks to the two-dimensional coherent integration gain utilized. Finally, several numerical simulations are conducted to show the validity of the proposed algorithm.

scholarly journals Refocusing of Ground Moving Targets with Doppler Ambiguity Using Keystone Transform and Modified Second-Order Keystone Transform for Synthetic Aperture Radar

2021 ◽  
Vol 13 (2) ◽  
pp. 177
Author(s):  
Jun Wan ◽  
Xiaoheng Tan ◽  
Zhanye Chen ◽  
Dong Li ◽  
Qinghua Liu ◽  
...  
Keyword(s):  
Synthetic Aperture Radar ◽  
Doppler Frequency ◽  
Second Order ◽  
Synthetic Aperture ◽  
Moving Target ◽  
Moving Targets ◽  
Cross Term ◽  
Keystone Transform ◽  
Spurious Peak ◽  
Aperture Radar

Ground moving targets will typically be defocused because of the range migration (RM) and Doppler frequency migration (DFM) caused by the unknown relative motions between the platform of synthetic aperture radar (SAR) and the ground moving targets. The received signal of the ground moving target easily exhibits the Doppler ambiguity, and the Doppler ambiguity leads to the refocusing difficulty of ground moving targets. To address these problems, a SAR refocusing method of ground moving targets with Doppler ambiguity based on modified second-order keystone transform (MSOKT) and keystone transform (KT) is presented in this paper. Firstly, the second-order phase is separated by the time reversing process. Secondly, MSOKT is performed to compensate the range curvature migration and DFM, and then the coefficient of the second-order phase is estimated. Finally, a well-refocused result of the moving target is achieved after KT and the estimated Doppler ambiguity number are used to eliminate residual range walk migration. The proposed method can accurately remove RM and DFM and effectively focus the moving targets without residual correction errors. Moreover, the effects of Doppler ambiguity (including Doppler center blur and spectrum split) and blind speed sidelobe are further avoided. On the basis of the analysis of cross-term for the multiple target case, the identification strategy of spurious peak of cross-term is proposed. Additionally, the developed method can be sped up by nonuniform fast Fourier transform without the interpolation operation. The effectiveness of the proposed method is verified by both airborne and spaceborne real data processing results.

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