Generation of local phase model of DOR tones for tracking deep space probes

In order to track deep space probes with very high accuracy, a type of VLBI technique called Δ DOR (Delta Differential One-way Ranging) has been investigated. The DOR signals emitted by deep space probes usually consist of several tones in a spanned bandwidth that can be extracted by correlation with a locally generated phase model. In this paper the method to generate a nonlinear phase model used for the local correlation of DOR tones is investigated and applied to the processing of a set of DOR data acquired from the ChangE-2 lunar satellite. The observations were conducted by the Chinese VLBI Network in a tracking pass in October 2010. The results indicate that the phase precisions of DOR tones could achieve at about 1 degree with 5s integration time, while the frequency precisions are about 1 mHz.