Differential VLBI Data Processing In The Deep Space Exploration

Differential VLBI in deep space navigation and positioning is essentially an ap-plication of the VLBI measurement techniques, including VLBI Phase-Referencing, broadband VLBI technique (△DOR:Delta-the Differential One-way Ranging), narrow-band VLBI technique (△DOD:Delta the Differential One-Way Doppler) and the same beam interferometric techniques. Differential VLBI technique began in the1970s, so far, the technology has played an important role in deep space exploration and a number of famous deep space exploration missions. After years the positioning accuracy has increased from the magnitude of more than ten mas to the magnitude of mas, recent-ly, the accuracy can be achieved0.1-0.2mas in the X-band when the separation angle between the reference source and the aircraft is about3-6degree, so, NASA requires the technology to be a regular detector navigation services. The first chapter is devoted to the development course of Differential VLBI in deep space exploration, a variety of Differential VLBI technique are described in Chapter two.Although the accuracy of the Differential VLBI technique are much better than the traditional VLBI, the technology is also facing many problems. The switch time between the reference source and the target source can not be very short because of the Engineering constraints, We can not always find a perfect reference source In the flight path of the aircraft, Especially in the changing or capturing stage, because of the ICRF is not very dense, the separation angle between the reference source and the aircraft will be10°. In the The third chapter, I analyzed the relationship between the switching time and the delay raised by the atmospheric, using a large number of VLBI measured data the Chang’e1(CE-1) and Chang’e2(CE-2)。 △DOR technology has been employed in satellite navigations as a test during Chang’e-2(CE-2) mission, the△DOR delay observables are obtained. In Chapter four, i introduced the preliminary analysis of DOR on the3th and4th in October. We got the delay and the delay rate, and we determinated the orbit According to the3hours later data (it means the precise orbit). I Analyzed the residual between the△DOR and the UXB, later.i determinate the orbit according to these data, and finded the difference.