天马望远镜在嫦娥三号测定轨VLBI观测中的应用分析
摘要
Tianma radio telescope (Shanghai 65-m radio telescope) finished the first stage of construction in October 2012, and was capable of doing VLBI observation in S/X, L, C band. It fully engaged in the mission of Chang'E-3 orbit and position determination with VLBI tracking in X band in December 2013. In Chang'E-3 mission, Tianma radio telescope replaced Shanghai 25-m radio telescope, thus improved the sensitivity of Chinese VLBI net by 1. 67 times. Meanwhile, using 2 bits quantization in Chang'E-3 instead of 1 bit quantization in Chang'E-2 made the sensitivity 1.38 times higher. After implementing the above 2 measures, the ΔDOR VLBI residual delay after determining orbit of Chang'E-3 was 0.67 ns, while the VLBI residual delay of Chang'E-2 was 1.77 ns. Furthermore, error of differential phase delay between the lander and rover of Chang'E-3 was down to 0.011 ps rms. This article introduces Tianma radio telescope and the system of X-band receiver and data acquisition, and analyses its application in Chang'E-3 mission.