Preliminary implementation of a Delta DOR algorithm

Delta-differential one-way ranging (Delta DOR) technique is an angle measurement method widely used in deep space exploration. Currently, cross-correlation methods are used to realize the Delta DOR technology in China's very long baseline interferometry networks. However, when a signal has a very low signal-to-noise ratio, the cross-correlation methods have a limited processing ability owing to a weak signal. With advancements in distant deep space exploration, calculating the time delay of weak signals has become necessary. In this paper, a high-performance third-order phase-locked loop is used as the basic module to measure the frequency and phase of a signal, and then a Delta DOR algorithm based on local correlation with high weak-signal-processing ability is derived. This algorithm avoids the performance loss caused by the cross-correlation between the local reference and received signals in a traditional local correlation method and is concise. The feasibility of the proposed method is indirectly verified by calculating the residual group delay of the observation data from Tianwen-1, thereby providing a scheme for the further development of the high-performance Delta DOR technique.