Development of three dimensional orbit determination by Doppler measurement between two satelites

我们试图通过调查与多普勒测量有关的可能的误差源，并通过开发一个新的电离层和对流层模型来获得最高的多普勒测量精度。首先，在测量了卫星发射的载波的频率稳定度和相位噪声后，推导了卫星自转对相位变化的影响。接下来，我们利用多普勒和VLBI数据进行了轨道确定的仿真，结果表明，结合多普勒和VLBI数据可以更好地恢复仅由多普勒测量恢复的肢体附近的重力场。接下来，我们对一种新的定轨方法进行了模拟，以了解在SELENE任务的情况下如何很好地恢复重力场。通过将VLBI与2路和4路多普勒测量相结合，将提高模型中包含的所有系数的精度。这里考虑了VLBI数据对确定Rstar精密轨道的影响，这是四向多普勒测量的参考。通过添加VLBI数据，33度以下的系数将提高约2倍，其中2次系数的改善最好，为2.6倍。如果能通过适当的力模拟使R/Vstar弧长大于1天，则Selene重力场的最终精度将比LP100J在30度以下的精度提高一个数量级。

We try to attain the highest accuracy in Doppler measurements by investigating possible error sources related to the Doppler measurements and by developing a new model of the ionosphere and the troposphere. First of all we formulated the effect of spin of a satellite on phase change after we measured frequency stability and phase noise of carrier wave emitted from the satellite. Next, we did a simulation of orbit determination by using Doppler and VLBI data and showed that gravity field near the limb, which was poorly recovered only by Doppler measurements, would be better recovered by combining the Doppler and VLBI data. Next, we ran a simulation of a new method for orbit determination in order to know how the gravity field would be well recovered for the case of SELENE mission. Accuracies of all the coefficients included in the model will be improved by combining VLBI with 2-way and 4-way Doppler measurements. What is accounted for here includes the effect of VLBI data on determining the precise orbit of the Rstar which is a reference of 4-way Doppler measurement. By adding VLBI data, the coefficients of degrees less than 33rd will be improved by about a factor of 2, with the best improvement in the 2nd degree coefficient by a factor 2.6. If we could make R/Vstar arc length to be longer than 1 day by proper force modeling, the final accuracy of SELENE gravity field will be one order of magnitude better than that of LP100J below degree around 30.