Dual-wavelength Satellite Laser Ranging Capabilities And Accuracy Improve

Satellite Laser Ranging(SLR) is a technique with the highest precision for a single-shot measurement of satellites. At present it has achieved a ranging precision of sub-centimeter. Atmospheric delay and the effect of retro-reflectors have become the main obstacles to upgrate the ranging accuracy. Up to now, Maini-Murray model is applied to determine the atmospheric delay, and its precision is about 5-10 millimeter. For a ranging precision of millimeter, SLR should operate at two-wavelength ranging mode to calibrate the atmospheric delay without model. In the present thesis, the early two-wavelength SLR system has been greatly updated. The key techniques are studied, including: the design of two-wavelength SLR system in hardware and software, the selection of optimal wavelength etc. Meanwhile the divergence and wobbling of Raman laser have been measured to research their ranging effect. The transmitting optical path difference between 683nm and 532nm has been lengthened for separating the mixing data in one channel, which improved the data pre-process precision.Considering preliminary stage experiment, this thesis lay great emphasis on solving following problems and makes two-color ranging the easier operating status: two color alignment with high accuracy, the fast and easily switching between routine and two-wavelength ranging and real time recording two counters data. Because of these work, the ability and precision of two-wavelength ranging in Shanghai station are greatly improved and reach the quasi-routing level. A large amount of effective data from LEO satellites is received. In the field of data processing softwares for two-color SLR have been established. Average ranging difference (ARD) and difference average ranging(DAR) processing methods are proposed and studied, analysis of ranging data are performed by adopting the two methods, the results show that they can achieve atmospheric delay with a higher precision than the one from measuring directly. The comparisons with Maini-Murray model show no significant deviations on present precision. Future plans for two-color SLR are proposed according to the real situation in Shanghai station and the developing trend of international SLR. With the application of Pico-second Event Timer and other advanced devices in SLR, the ranging data of two-wavelength SLR can be used to determine the atmospheric delay with a high precision than model based on the thesis research.