Geometric Calibration and Accuracy Verification of the GF-3 Satellite

Abstract

The GF-3 satellite is the first multi-polarization synthetic aperture radar (SAR) imaging satellite in China, which operates in the C band with a resolution of 1 m. Although the SAR satellite system was geometrically calibrated during the in-orbit commissioning phase, there are still some system errors that affect its geometric positioning accuracy. In this study, these errors are classified into three categories: fixed system error, time-varying system error, and random error. Using a multimode hybrid geometric calibration of spaceborne SAR, and considering the atmospheric propagation delay, all system errors can be effectively corrected through high-precision ground control points and global atmospheric reference data. The geometric calibration experiments and accuracy evaluation for the GF-3 satellite are performed using ground control data from several regions. The experimental results show that the residual system errors of the GF-3 SAR satellite have been effectively eliminated, and the geometric positioning accuracy can be better than 3 m.

First Spaceborne SAR-GMTI Experimental Results for the Chinese Gaofen-3 Dual-Channel SAR Sensor

“…The resolution of Gaofen-3 SAR sensor ranges from 1 m to 500 m, while the corresponding swath ranges from 10 km up to 650 km. Thus far, 12 imaging modes [ 29 , 30 , 31 , 32 ] have been designed and successfully implemented on this sensor.…”

“…This sensor is equipped with a wave-guide slot phased array with length 15 m and height 1.5 m [ 29 , 32 ], which can be divided into two halves in azimuth on reception. Based on this architecture, a dual receive channel (DRC) mode based on ultra-fine strip (UFS) mode has been implemented on Gaofen-3 for HRWS imaging of static scene and moving targets purposes [ 33 ].…”

A Quality Assessment Method Based on Common Distributed Targets for GF-3 Polarimetric SAR Data

“…Many countries have paid attention to the development of PolSAR systems, and have launched a series of space-borne PolSAR systems, such as Radarsat-2, TerraSAR-X, ALOS-2, Sentinel-1 and Cosmo-Skymed. In August 2016, China launched its first PolSAR satellite—GF-3—which works at the C band and has 12 imaging modes with resolution up to 1 m [ 7 , 8 ]. All imaging modes of this satellite are available in either left- or right-looking orientation.…”

Feasibility of Replacing the Range Doppler Equation of Spaceborne Synthetic Aperture Radar Considering Atmospheric Propagation Delay with a Rational Polynomial Coefficient Model

“…Based on the experimental data of the GF-3 satellite and GCPs, geometric positioning verification experiments were performed for the four RPC models, and the results are shown in Table 4. (1) Firstly, for the RPC model fitted using the original RD model without atmospheric delay correction, positioning accuracy verification was conducted; (2) After correcting the systematic error in the slant range direction of the GF-3 SAR satellite, geometric positioning accuracy verification of the RPC model was performed. This systematic error was obtained by geometric calibration of the spaceborne SAR [23]; (3) After correcting the systematic error in the slant range direction of the GF-3 SAR satellite and correcting the atmospheric propagation delay error using plan 1, geometric positioning accuracy verification of the RPC model was performed; (4) After correcting the systematic error in the slant range direction of the GF-3 SAR satellite and correcting the atmospheric propagation delay error using plan 2, geometric positioning accuracy verification of the RPC model was performed. Table 4 shows that the positioning accuracy of the RPC model is between 21.241 m and 26.004 m without correction of system error and atmospheric delay error.…”