VLBI相时延及其在深空探测器测定轨中的应用

Abstract

As one of the key technologies for orbit determination, very long baseline interferometry (VLBI) will play an important role in deep space explorations. The traditional group delay of VLBI is affected by the signal to noise ratio (SNR). As the spacecraft going to outer space, the random error of group delay increases quickly because of the SNR getting worse and worse. In this paper, we introduce the phase delay whose random error is much smaller than that of group delay at the same SNR. We deduce the conditions and method to determine the phase ambiguity, and then give the formula of calculating phase delay. The phase delay is used to determine the orbit of Change 2 (CE2) satellite with Doppler/ranging data when it flies to the Sun-Earth Lagrangian point L2 which is 1 500 000 km away from the Earth. It proves that the phase delay is useful for orbit determination.