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A Synthetic Bandwidth Method for High-Resolution SAR Based on PGA in the Range Dimension.

Li J, Chen J, Liu W, Wang P, Li C - Sensors (Basel) (2015)

Bottom Line: The synthetic bandwidth technique is an effective method to achieve ultra-high range resolution in an SAR system.Furthermore, an improved cut-paste method is proposed to combine the signals in the frequency domain.Imaging results based on both simulated and real data are presented to validate the proposed approach.

View Article: PubMed Central - PubMed

Affiliation: School of Electronic and Information Engineering, Beihang University, Beijing 100191, China. lijincheng_buaa@163.com.

ABSTRACT
The synthetic bandwidth technique is an effective method to achieve ultra-high range resolution in an SAR system. There are mainly two challenges in its implementation. The first one is the estimation and compensation of system errors, such as the timing deviation and the amplitude-phase error. Due to precision limitation of the radar instrument, construction of the sub-band signals becomes much more complicated with these errors. The second challenge lies in the combination method, that is how to fit the sub-band signals together into a much wider bandwidth. In this paper, a novel synthetic bandwidth approach is presented. It considers two main errors of the multi-sub-band SAR system and compensates them by a two-order PGA (phase gradient auto-focus)-based method, named TRPGA. Furthermore, an improved cut-paste method is proposed to combine the signals in the frequency domain. It exploits the redundancy of errors and requires only a limited amount of data in the azimuth direction for error estimation. Moreover, the up-sampling operation can be avoided in the combination process. Imaging results based on both simulated and real data are presented to validate the proposed approach.

No MeSH data available.


Flow diagram of the proposed method.
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f6-sensors-15-15339: Flow diagram of the proposed method.

Mentions: We here propose a novel reconstruction method composed of two PGA-based range error correction steps and an improved combination method. Figure 6 shows the flowchart of the proposed synthetic bandwidth construction method. There are three main parts. The first part is the first-order error correction, which estimates errors from the internal calibration data and compensates them for the radar data in the frequency domain. Next is the combination operation by the improved cut-paste method in which the up-sampling operation and the special design of the radar parameters of the traditional combination method [6,10,11] can be avoided. After the above processing, the combined chirp signal is obtained. Then, the imaging algorithm, such as the range Doppler algorithm (RDA), the chirp scaling algorithm (CSA), and the wave-number algorithm (ωkA), etc., can be implemented. The last part is the second-order error correction, which removes the residual amplitude and phase errors in the azimuth-compressed domain. In the following, details of the operations are provided.


A Synthetic Bandwidth Method for High-Resolution SAR Based on PGA in the Range Dimension.

Li J, Chen J, Liu W, Wang P, Li C - Sensors (Basel) (2015)

Flow diagram of the proposed method.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4541834&req=5

f6-sensors-15-15339: Flow diagram of the proposed method.
Mentions: We here propose a novel reconstruction method composed of two PGA-based range error correction steps and an improved combination method. Figure 6 shows the flowchart of the proposed synthetic bandwidth construction method. There are three main parts. The first part is the first-order error correction, which estimates errors from the internal calibration data and compensates them for the radar data in the frequency domain. Next is the combination operation by the improved cut-paste method in which the up-sampling operation and the special design of the radar parameters of the traditional combination method [6,10,11] can be avoided. After the above processing, the combined chirp signal is obtained. Then, the imaging algorithm, such as the range Doppler algorithm (RDA), the chirp scaling algorithm (CSA), and the wave-number algorithm (ωkA), etc., can be implemented. The last part is the second-order error correction, which removes the residual amplitude and phase errors in the azimuth-compressed domain. In the following, details of the operations are provided.

Bottom Line: The synthetic bandwidth technique is an effective method to achieve ultra-high range resolution in an SAR system.Furthermore, an improved cut-paste method is proposed to combine the signals in the frequency domain.Imaging results based on both simulated and real data are presented to validate the proposed approach.

View Article: PubMed Central - PubMed

Affiliation: School of Electronic and Information Engineering, Beihang University, Beijing 100191, China. lijincheng_buaa@163.com.

ABSTRACT
The synthetic bandwidth technique is an effective method to achieve ultra-high range resolution in an SAR system. There are mainly two challenges in its implementation. The first one is the estimation and compensation of system errors, such as the timing deviation and the amplitude-phase error. Due to precision limitation of the radar instrument, construction of the sub-band signals becomes much more complicated with these errors. The second challenge lies in the combination method, that is how to fit the sub-band signals together into a much wider bandwidth. In this paper, a novel synthetic bandwidth approach is presented. It considers two main errors of the multi-sub-band SAR system and compensates them by a two-order PGA (phase gradient auto-focus)-based method, named TRPGA. Furthermore, an improved cut-paste method is proposed to combine the signals in the frequency domain. It exploits the redundancy of errors and requires only a limited amount of data in the azimuth direction for error estimation. Moreover, the up-sampling operation can be avoided in the combination process. Imaging results based on both simulated and real data are presented to validate the proposed approach.

No MeSH data available.