A numerical model for solving time delay and phaseinconsistency problem in the data acquisition system ofvery long baseline interferometry

摘要

We developed an advanced data acquisition system for the very long baseline interferometry used for deep-space detection in recent years. However, there are serious time delay and phase inconsistency problems in the data acquisition system, which greatly increase the complexity of subsequent processors and reduce measurement accuracy. To solve the problem, we establish a numerical model to analyze the specific reasons and propose a novel scheme to achieve a much better performance by optimizing the mixed digital direct synthesizer (DDS) for frequencies. We find that the DDS module cannot output an accurate phase and correct this inaccuracy by changing the original design of DDS module. Simulation and measurement results show that the redesign of DDS can remove the inconsistency of time delay and phases and improve the mixed performance.