基于时间误差补偿的HJ-1C卫星几何定位改进

利用距离多普勒算法对 HJ-1C（“环境一号”C）卫星图像进行定位，其初始定位精度为1100~1400m，不能很好地满足实际应用的需要。进一步分析后发现，HJ-1C卫星图像几何定位误差主要分布在方位向，通过对影响HJ-1C卫星几何定位精度的因素进行分析，得出合成孔径雷达（Synthetic Aperture Radar, SAR）时间误差是影响几何定位的关键因素，因此文章提出通过时间误差补偿提高HJ-1C卫星几何定位精度。该方法首先计算SAR时间误差，然后对SAR载荷时间进行补偿，最后利用距离多普勒算法进行定位，并对HJ-1C卫星图像进行了验证。结果表明，HJ-1C卫星定位精度提高到300m左右，得到了有效的改进。

Location Improvement of HJ-1C Satellite Based on Time Error Compensation

Range Doppler algorithm is used for image location of HJ-1C satellite . The initial location accuracy is about 1 100~1 400m, which cannot meet the needs of the application properly. Furthermore, azi-muth error is the major location error of HJ-1C image. By analyzing the impact factors on the HJ-1C satellite location accuracy, it is concluded that time error is the most critical factor affecting the geometric location. So the time error needs to be compensated. First SAR time errors need be calculated and compensated. Secondly, range Doppler algorithm is used for location. Finally the method is verified by HJ-1C satellite images. The re-sults indicate that location accuracy of HJ-1C satellite is improved from 1 100~1 400m to around 300m.