我国自主火星探测及计划开展的月-地VLBI将面临弱DOR信标的干涉测量问题。现有VLBI测轨分系统任务处理机不适用于弱DOR信标的处理。本项目研究弱DOR信标的射电干涉测量并编写处理软件。DOR信标载噪比处理最低门限指标为：主载波13dBHz、侧音1dBHz，对应的探测器DOR时延热噪声优于1ns，该指标可用于星载弱DOR信标的处理。针对火星探测器1ns的Delta-DOR精度要求，本项目需要的DOR侧音载噪比为10dBHz，比应用于工程任务的处理机低13dBHz，扩容了工程项目所需的信噪比最低门限。本项目将对月-地DOR信标处理进行预研，研究月-地DOR信标处理、模型的计算，研究星载天线位置偏差、星载原子钟稳定性对月-地DOR测量精度的影响。

Mars exploration and Moon-Earth VLBI in the future will face low-SNR DOR interference processing. The existing VLBI correlator for deep space is not suitable for low-SNR DOR process. This project will research low-SNR DOR process and writes the processing software.The minimum SNR threshold of DOR tone is: main carrier 13dBHz and tone 1dBHz, and thermal noise error is 1ns. The low-SNR target will suitable for moon-earth DOR process. The minimum SNR of DOR tone for Mars exploration is 10dBHz in the project, which is 13dBHz lower than the SNR minimum threshold of correlator in Mars mossion. Besides low-SNB DOR, Moon-Earth VLBI will research how to calculate light-time model between deep spacecraft and space VLBI station. We’ll also research DOR error caused by the uncertainty of antenna position of space VLBI station and the stability of spaceborne atomic clocks.