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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.


Schematic diagram of an internal calibration system.
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f5-sensors-15-15339: Schematic diagram of an internal calibration system.

Mentions: Generally, the internal calibration data can be employed to correct the instrument effect on SAR range behaviour [15]. Figure 5 shows the schematic diagram of the internal calibration system [3,8]. In the calibration mode, the excitation source generates a calibration pulse with the same length and bandwidth as the transmitted pulse commanded for the imaging mode. As shown in Figure 5, except for the radar antennas, the calibration signal goes through the transmitting and receiving path directly. Hence, the received calibration pulse is equivalent to the signal of the point target with the slant range being zero. The internal calibration signal is equipped with the feature of the radar system. Therefore, the internal calibration signal can be used to estimate system errors.


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)

Schematic diagram of an internal calibration system.
© Copyright Policy
Related In: Results  -  Collection

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

f5-sensors-15-15339: Schematic diagram of an internal calibration system.
Mentions: Generally, the internal calibration data can be employed to correct the instrument effect on SAR range behaviour [15]. Figure 5 shows the schematic diagram of the internal calibration system [3,8]. In the calibration mode, the excitation source generates a calibration pulse with the same length and bandwidth as the transmitted pulse commanded for the imaging mode. As shown in Figure 5, except for the radar antennas, the calibration signal goes through the transmitting and receiving path directly. Hence, the received calibration pulse is equivalent to the signal of the point target with the slant range being zero. The internal calibration signal is equipped with the feature of the radar system. Therefore, the internal calibration signal can be used to estimate system errors.

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.