低低卫卫跟踪(SST-ll)具备高精度获取地球重力场时变信息的优势，而且随着激光测距等技术的发展，SST-ll恢复重力场精度的提升潜力大，将作为下一代重力卫星计划的主要测量模式，因此开展相应的误差分析研究有着重要科学意义和应用价值。随着解算模型分辨率的增加，急剧增长的计算量和数值不稳定性问题已成为制约误差分析研究的主要因素，建立高效、稳定的评估SST-ll恢复重力场精度的方法是开展下一代重力卫星计划研究的重要环节。本项目拟在重力场频谱分析的基础上，利用二维傅立叶变换性质、调制理论和轨道扰动理论建立测量噪声功率谱与重力位系数恢复精度的直接对应关系，即从信号理论的角度建立两者的传递函数。本项目的研究结果可以快速、直接地分析SST-ll中轨道参数和载荷噪声的影响，并回答定轨精度、加速度计和星间距测量精度的需求以及匹配关系，为下一代卫星重力测量计划的初期选取和确定相应载荷指标提供理论指导。

Satellite-to-satellite low-low tracking (SST-ll) has an advantage to obtain the time-variable gravity field information with high precision and a huge potential for accuracy gains as it adopts Laser Ranging system, so it is the main mode of the next generation gravity mission. As a result, it is significant to discuss the error analysis of SST-ll. The latest and incoming gravitational models with increasing accuracy and resolution make the computation more difficult since the computation becomes huge and serious numerical instabilities arise when degree/order of models gets higher. It is significant to establish an effective and stable method to analyze the relationship between parameters and scientific requirements and the effects of the measurement noise on accuracies of the recovery of gravity fields. A direct relationship between the power spectrum density (PSD) of SST-ll observations and the coefficients of the Earth’s gravity potential is established based on 2-D FFT, modulation theorem and orbit perturbation theory. Essentially, the aim of this study is to obtain the transfer function between them. The results of this research can directly determine the requirements of the accuracies of orbit determination, accelerometers and ranging system, analyze the matching relationship among these terms, and is useful to design and verify the parameters for the next generation gravity mission.