基于△DOR信号的高精度VLBI技术

在嫦娥二号（CE-2）工程中，我国首次开展了X波段ADOR测量实验，获取了ADOR信号的VLBI时延数据，并用于精密定轨．本文给出了CE-2中ADOR信号的VLBI测量与数据处理方法，结合我国VLBI测量系统对时延数据进行了误差分析及精密定轨分析．结果表明：ADOR信号的VLBI时延精度优于0．5ns，比利用S波段信标的测量精度提高约一个数量级．本研究成果为后续的月球及深空探测高精度测定轨提供了重要的技术手段．

High-accuracy VLBI technique using △DOR signals

During the Chinese Lunar Project Chang＇E-2 mission, a series of experiments on △DOR （delta differential one-way ranging） technology was carried out over a two week period starting on April 2, 2011. △DOR technology was first adopted in China deep space navigation, and the ADOR delay observables were obtained and used for orbit determination. In this paper, we introduce the ADOR observing technology, including the ADOR measurenmnt principles. We also discuss the experiment design, the rules for selecting the calibration quasars, the switching time choice, the signal recording setup for the channels, the △DOR data processing method implemented in the software, and our analysis of the error sources of the ADOR delay and its contribution to orbit determination based on the characteristics of the Chinese VLBI network. Through these analyses and verification studies on the orbit determination from the satellite orbits in the CE-1 and CE-2 missions, we conclude that the accuracy of the ADOR delay is about 0.5 ns, an improvement of about one order of magnitude compared with that from S-band telemetry signals of less than 1 MHz. This study presents an important technique for high precision orbit determination of lunar and deep space explorations.