The Uplink VLBI Receiving System for Deep Space Exploration in the Spacecraft

In deep space telemetry tracking and command (TT&C) missions, the low signal-to-noise ratio (SNR) of the receiving signal restricts the improvement of measurement performance. In the article, we adopt the uplink signal which transmitted by the ground station to achieve very long baseline interferometry (VLBI) in the spacecraft. Notably, this methodology guarantees an SNR enhancement of at least 30 dB compared to the downlink signal, marking a significant improvement. Considering the restrict of spacecraft calculate resources, we adopt multiple baselines to simplify the VLBI method in spacecraft receiver and obtain the high accuracy angle measurement results. The simulation and analysis show that the algorithm achieves a measurement accuracy of 0.77 nrad on the baseline length of 74 km, while the accuracy of traditional delta differential one-way ranging (Delta DOR) observations is 1 nrad with an 8400 km baseline length. In addition, we design a hardware platform for algorithm verification. This platform, under real-world conditions, exhibits an angle measurement error of less than 5 mrad even with a baseline length as short as 0.74 m.