A Robust Algorithm Research And Design For Ambiguity Resolution And Angle Measurement In Lunar Rendezvous Radar Interferometry

As china started a lot of space activities, in order to meet the increasingly complex space missions, space science and technology becomes more and more important. China’s Lunar Exploration Program, rendezvous and docking(RVD) in lunar orbit is the key technology to tack back the lunar rover, human exploration missions to the moon and other space missions. RVD is a technology to achieve rendezvous and docking between spacecrafts. it is one of the core technologies to execute Round Trip Transportation of people and goods, on-orbit Maintenance, on-orbit assembly, etc. RVD system consists of rendezvous system and docking system. Rendezvous system accomplished the measurements in long distance, mainly on the measurements of relative distance, relative speed and relative location. And docking system is responsible for spacecrafts’ docking at close range. Internationally, microwave radar is used to measure the range, the speed and the angle in the rendezvous systems when spacecrafts are in rendezvous process. This paper studies the algorithm for angle measurement with interferometer in a microwave rendezvous radar system, and on this basis, analyzes the feasibility of spread spectrum receiver’s cycle slip detection and repair technology applied in the angle measurement.The main work of this paper is to study the algorithm for angle measurement with interferometer in a microwave rendezvous radar system. This paper describes and analyzes the angle measurement principle of interferometer, the sources of angle measurement error, mean filter and Kalman filter algorithm principle, and cycle slip detection and repair technology’s concepts and principles. On this basis, for dualbaseline interferometer system, gives an algorithm for ambiguity resolution and angle measurement through search method and an algorithm of ambiguity resolution and angle measurement through successive step method, and their mathematical derivation, theoretical analysis, and do some simulations. Then for single-baseline interferometer system, on condition of dual-frequency, this paper gives an algorithm for ambiguity resolution and angle measurement, on condition of tri-frequency, gives an algorithm of ambiguity resolution and angle measurement through search method,an algorithm of ambiguity resolution and angle measurement through successive step method, and an algorithm of ambiguity resolution and angle measurement through square method. And it also gives their mathematical derivation, theoretical analysis, and also do some simulations. In the simulation experiments of algorithms for ambiguity resolution and angle measurement, the performance of the algorithms for ambiguity resolution and the performance of the algorithms for angle measurement are compared and analyzed through simulation results in different filters. Finally, polynomial fitting in the detection and repair of cycle slip are discussed and simulated, then the feasibility of cycle slip detection and repair technology in the application of the interferometer was analyzed and simulation.The simulation results obtained by Matlab show that the algorithms for ambiguity resolution and angle measurement proposed in this paper have good performance of the algorithms for ambiguity resolution and the performance of the algorithms for angle measurement, to meet the lunar orbit rendezvous radar microwave measurement requirements. Meanwhile, the application of cycle slip detection and repair technology can effectively reduce the probability of ambiguity resolution errors, and improve the robustness of the performance of algorithms for ambiguity resolution.