New Doppler frequency rate estimation method for spaceborne synthetic aperture radars

1998 ◽  
Author(s):  
Yuping Cheng ◽  
Zheng Bao
Keyword(s):  
Estimation Method ◽  
Doppler Frequency ◽  
Synthetic Aperture ◽  
Rate Estimation ◽  
Frequency Rate ◽  
Synthetic Aperture Radars

A FrFT Based Algorithm for Doppler Frequency Rate Estimation from LFM Coherent Pulse Train

2010 ◽  
Vol 32 (11) ◽  
pp. 2718-2723 ◽  
Author(s):  
Hong Li ◽  
Yu-liang Qin ◽  
Yan-peng Li ◽  
Hong-qiang Wang ◽  
Xiang Li
Keyword(s):  
Pulse Train ◽  
Doppler Frequency ◽  
Rate Estimation ◽  
Frequency Rate ◽  
Coherent Pulse

scholarly journals Estimation Method of SAR Doppler Frequency Rate Based on FrFT

2020 ◽  
Vol 38 (6) ◽  
pp. 1352-1360
Author(s):  
Ying Chen ◽  
Tao Chen ◽  
Kewei Li ◽  
Julan Xiao ◽  
Hongli Liu
Keyword(s):  
Present Method ◽  
Pulse Compression ◽  
Estimation Method ◽  
Doppler Frequency ◽  
Real Data ◽  
Estimation Accuracy ◽  
Optimal Order ◽  
Maximum Point ◽  
Frequency Rate ◽  
Strong Scattering

Due to the problem that the existing Doppler frequency rate estimation method is limited by the estimation accuracy, a novel estimation method of Doppler frequency rate is proposed. The present method searches the frequency rate according to the characteristic of the chirp signal in the FrFT domain. Firstly, dechirp is performed on several strong scattering points extracted from the data domain after pulse compression, and a frequency domain focused image is obtained after FFT. Then the maximum point of each distance unit is extracted. The energy of the maximum point is selected by using the window processing. After that, IFFT is performed and the dechirp conjugate reference function is multiplied by using the selected points. FrFT is performed according to the preset orders. The entropy is used to evaluate whether the order of FRFT is optimal or not. The Doppler frequency rate is calculated by using the optimal order. The simulation and real data are processed and analyzed. The present method can estimate the Doppler frequency rate accurately. A well-focused SAR image is obtained after azimuth matching filtering.

scholarly journals An Adaptive Hierarchical Detection Method for Ship Targets in High-Resolution SAR Images

2020 ◽  
Vol 12 (2) ◽  
pp. 303 ◽  
Author(s):  
Yi Liang ◽  
Kun Sun ◽  
Yugui Zeng ◽  
Guofei Li ◽  
Mengdao Xing
Keyword(s):  
Detection Method ◽  
Estimation Method ◽  
Kernel Density ◽  
Image Resolution ◽  
Synthetic Aperture ◽  
Sar Images ◽  
Airborne Sar ◽  
Visual Attention Mechanism ◽  
Synthetic Aperture Radars ◽  
Coarse To Fine

With the improvement of image resolution in synthetic aperture radars (SARs), sea clutter characteristics become more complex, which poses new challenges to traditional ship target detection missions. In this paper, to detect ship targets quickly and efficiently in a complex background, we propose an adaptive hierarchical detection method based on a coarse-to-fine mechanism. This method constructs a new visual attention mechanism to strengthen ship targets and obtain the candidate targets adaptively by the means dichotomy method. On this basis, the precise detection results of the targets are obtained using the speed block kernel density estimation method, which maintains constant false alarm characteristics. Compared with existing methods, the adaptive hierarchical detection method has simple, fast, and accurate characteristics. Experiments based on GF-III satellite and airborne SAR datasets are presented to demonstrate the effectiveness of the proposed method.

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