Abstract
<p indent="0mm">During deep space exploration activities, solar conjunction occurs due to changes in the relative motion between the Earth, the spacecraft and the Sun. During solar conjunction, the main beam of the antenna of the ground deep space TT&C equipment is aligned with the spacecraft as well as the sun. At this time, the strong electromagnetic radiation generated by the sun will enter the main beam of the ground deep space TT&C antenna and bring strong interference to the spacecraft signal received. Therefore, solar noise is an important factor affecting the performance of deep space TT&C communication link. During China’s first Mars Exploration Mission—Tianwen-1, the opportunity of the Sun-Earth-Mars angle-off less than 5° will be used for the first time, that is, from September 23 to October 23, 2021, the <sc>35 m</sc> diameter deep space TT&C equipment of China’s Deep Space Tracking and Control Network located in Kashi, Xinjiang and Jiamusi, Heilongjiang. The influence of solar noise on the TT&C communication link of Tianwen-1 during solar conjunction was studied, the latest experimental results were obtained, and the preliminary law of the influence of solar noise on the X band TT&C link of China’s deep space TT&C equipment when the distance from the Earth is 400 million kilometers was obtained. The completeness and correctness of the downlink telemetry data after frame synchronization of the deep space TT&C station were verified, and the effect of solar noise on the reception performance of the deep space TT&C station was evaluated by calculating the frame error rate of the telemetry received. According to data analysis, when the azimuth deviation angle is less than 3°, the influence of solar thermal noise increases, and when the azimuth deviation angle is less than 1°, the influence of solar thermal noise increases significantly. When the deviation angle is less than 2°, the influence of solar thermal noise increases, and when the deviation angle is less than 0.5°, the influence of solar thermal noise increases significantly. Since the Tianwen-1 Mission is in the midst of an 11-year lull in solar activities, the impact of solar noise is relatively small. During the extended mission of Tianwen-1, the ground deep space TT&C system will continue to monitor the influence of the TT&C link during solar conjunction, and strive to obtain the influence information of a complete solar activity cycle, so as to provide more accurate reference for the analysis of the influence of solar noise in the subsequent deep space exploration activities. Considering that Ka-band will be an important frequency band for deep space TT&C communication in the future, it is necessary to further strengthen research and experimental verification of the influence of solar noise on the deep space TT&C link at Ka-band.
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