卫星位置误差对GPS共视时间比对的影响
Effect of the Error of Satellite Position on GPS Common-view Time Transfer
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摘要: 影响GPS共视时间比对的一种因素是卫星的位置误差,这个影响程度取决于用户对卫星的观测仰角和用户间的基线长度。当两个用户的仰角大致相同时,卫星位置误差对时间比对的影响与基线长度近似成正比,而与仰角的大小几乎无关。当两个仰角不同时,对于小于2500km的基线,两个仰角之差越小,这种影响就越小。对于5000km以内的基线,无论多大的仰角,时间比对的误差最多相当于卫星位置等价误差(卫星位置误差除以信号传播速度)的四分之一。Abstract: A factor affecting the accuracy of GPS common-view time transfer is the satellite position error. The effect extent depends on the elevation and the length of baseline. When the two elevations are the same,a longer baseline increases the effect of the satellite position error on the time transfer,and the effect is approximately proportional to the baseline length. When the two elevations are different,a smaller difference between elevations leads to a smaller effect when baselines is less than 2 500 km. For a baseline is less than 5 000 km,whatever elevations are used,the time transfer error is no more than a quarter of the satellite position error divided by the speed of light.