Ground Positioning Method of Spaceborne SAR High-Resolution Sliding-Spot Mode Based on Antenna Pointing Vector
Abstract
:1. Introduction
2. Dechirp Influence on Squint Sliding-Spot Imaging Mode
3. Geometric Processing Principle of Spaceborne SAR High-Resolution Sliding-Spot Mode Based on Antenna Pointing Vector
3.1. Extension of the Range–Doppler Model after Dechirp
3.2. The Geometric Forward Calculation Process
3.3. The Geometric Inverse Calculation Process
- a)
- Convert to 3D coordinates under WGS84.
- b)
- Set the initial value . is the total number of lines in the azimuth direction of the slant range image.
- c)
- Let . Suppose the satellite locates at point and at time and , respectively. Calculate the distances between the two points and T, respectively, and remove the near slant range to find the difference between the two .
- d)
- If , it indicates that the target azimuth coordinate is between to , let . Otherwise, it indicates that the target azimuth coordinate is between to , let .
- e)
- If , go to (c) to execute a new loop, otherwise the loop ends, and is the azimuth image coordinate of the target T, and its range image coordinate is calculated as .
4. Experiment of Geometry Processing Accuracy Evaluation
4.1. Introduction of Experimental Data
4.2. Geometric Calibration Results
4.3. Geometric Positioning Results after Calibration
4.4. Influence of Different Precision Elevation Data on Positioning Accuracy
5. Conclusions
Author Contributions
Funding
Data Availability Statement
Conflicts of Interest
References
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Satellite orbit altitude | 600 km |
Squint scanning angle range | 4.93–13.13 degrees |
Center side-looking angle | 27 degrees |
Range bandwidth | 800 MHz |
Range sampling rate | 1000 MHz |
Satellite platform velocity | 7.62 km/s |
Pulse repetition frequency (PRF) | 5182 Hz |
Imaging time | 15.26 s |
Range sampling point number in the imaging area | 25,600 |
Azimuth sampling point number in the imaging area | 46,272 |
Pulse-Width and Bandwidth Combination ID | Incalib Image ID | Central Side-Looking Angle | Orbit | Looking Side |
---|---|---|---|---|
B1 | Image 1 | 50.27 | Ascend | Right |
Image 2 | 47.93 | Descend | Left | |
Image 3 | 47.43 | Descend | Left | |
B2 | Image 4 | 28.44 | Descend | Left |
B3 | Image 5 | 54.92 | Descend | Left |
Image 6 | 52.11 | Ascend | Right | |
Image 7 | 53.21 | Descend | Left | |
Image 8 | 53.21 | Ascend | Left | |
Image 9 | 44.96 | Ascend | Left | |
Image 10 | 50.7 | Ascend | Right | |
Image 11 | 58.86 | Ascend | Right | |
B4 | Image 12 | 39.37 | Ascend | Left |
B5 | Image 13 | 23.62 | Ascend | Right |
Image 14 | 18.33 | Descend | Right | |
Image 15 | 31.39 | Ascend | Right | |
Image 16 | 29.44 | Ascend | Left | |
Image 17 | 23.62 | Ascend | Left | |
B6 | Image 18 | 57.2 | Descend | Left |
Pulse-Width and Bandwidth Combination ID | Test Image ID | Central Side-Looking Angle | Orbit | Looking Side |
---|---|---|---|---|
B1 | Image 1 | 48.43 | Descend | Left |
Image 2 | 48.18 | Descend | Right | |
Image 3 | 51.72 | Ascend | Left | |
B2 | Image 4 | 28.94 | Ascend | Left |
Image 5 | 28.94 | Descend | Right | |
Image 6 | 21.32 | Ascend | Right | |
B3 | Image 7 | 50.7 | Ascend | Left |
Image 8 | 49.14 | Ascend | Left | |
B4 | Image 9 | 34.99 | Ascend | Left |
Image 10 | 34.56 | Descend | Right | |
Image 11 | 42.16 | Ascend | Left | |
B5 | Image 12 | 29.94 | Descend | Left |
Image 13 | 25.27 | Ascend | Left | |
Image 14 | 19.54 | Descend | Right |
Pulse-Width and Bandwidth Combination | The Number of Images Involved in the Calibration | Incalib 1 (No Image Removed) | Incalib 2 (Abnormal Images Removed) | ||
---|---|---|---|---|---|
Slant Range Calibration Result (m) | Azimuth Time Calibration Result (ms) | Slant Range Calibration Result (m) | Azimuth Time Calibration Result (ms) | ||
B1 | 3 | 12.046 | 3.333 | 13.035 | 1.126 |
B3 | 7 | 12.367 | 3.708 | 12.93 | 2.160 |
B5 | 5 | 9.946 | 2.661 | 10.662 | 1.809 |
Corner Reflector ID | Field Measurement (m) | ASTER DEM (m) | Global DEM (m) |
---|---|---|---|
1 | 1087.467 | 1098 | 1094 |
2 | 1068.961 | 1087 | 1101 |
3 | 1091.221 | 1108 | 1122 |
4 | 1090.578 | 1096 | 1090 |
5 | 1089.080 | 1097 | 1107 |
6 | 1091.104 | 1104 | 1121 |
7 | 1092.414 | 1095 | 1121 |
8 | 1092.992 | 1099 | 1123 |
9 | 1093.143 | 1104 | 1119 |
Medium error | ±11.240 | ±24.984 |
ID | Side Looking | Elevation Source | Positioning Error | ||
---|---|---|---|---|---|
Range | Azimuth | Plane | |||
Test Image 14 | Left view 19.54 degree | Field measurement | 1.721110 | 0.218848 | 1.734968034 |
ASTER DEM | 11.113978 | 0.594016 | 11.12984106 | ||
Global DEM | 22.464659 | 1.344352 | 22.50484806 | ||
Test Image 9 | Left view 34.99 degree | Measured elevation | 1.118257 | −2.620450 | 2.849080013 |
ASTER DEM | 8.961166 | −2.861411 | 9.406921334 | ||
Global DEM | 18.429528 | −3.102371 | 18.68882576 | ||
Test Image 3 | Left view 51.72 degree | Measured elevation | 0.396214 | −1.631593 | 1.679011987 |
ASTER DEM | 5.514775 | −1.750255 | 5.785856537 | ||
Global DEM | 11.693389 | −1.898581 | 11.84651662 |
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Li, Y.; Wu, H.; Meng, D.; Gao, G.; Lian, C.; Wang, X. Ground Positioning Method of Spaceborne SAR High-Resolution Sliding-Spot Mode Based on Antenna Pointing Vector. Remote Sens. 2022, 14, 5233. https://doi.org/10.3390/rs14205233
Li Y, Wu H, Meng D, Gao G, Lian C, Wang X. Ground Positioning Method of Spaceborne SAR High-Resolution Sliding-Spot Mode Based on Antenna Pointing Vector. Remote Sensing. 2022; 14(20):5233. https://doi.org/10.3390/rs14205233
Chicago/Turabian StyleLi, Yingying, Hao Wu, Dadi Meng, Gemengyue Gao, Cuiping Lian, and Xueying Wang. 2022. "Ground Positioning Method of Spaceborne SAR High-Resolution Sliding-Spot Mode Based on Antenna Pointing Vector" Remote Sensing 14, no. 20: 5233. https://doi.org/10.3390/rs14205233
APA StyleLi, Y., Wu, H., Meng, D., Gao, G., Lian, C., & Wang, X. (2022). Ground Positioning Method of Spaceborne SAR High-Resolution Sliding-Spot Mode Based on Antenna Pointing Vector. Remote Sensing, 14(20), 5233. https://doi.org/10.3390/rs14205233