ONBOARD SYNCHRONIZING NAVIGATION-TIMING DEVICE FOR SPACE VEHICLES. TESTS AND SIMULATION RESULTS

摘要

The results are presented as regards development and testing an onboard synchronization positioning/timing device (OSPTD). The OSPTD is purposed for high-accuracy navigation/timing supporting low- and medium- orbit SVs. The OSPTD contains onboard Synchronization Module and onboard GLONASS/GPS Receiver Module. Such an integration enables one to solve both tasks of synchronizing the SV time and tasks of SV navigation without using aids of the ground-based control segment. In the end it resulted in the improvement of accuracy parameters for SVs' navigation/timing support and the significant reduction in expenses for operations of control and SVs' trajectory ballistic support. As result of full-scale testing of OSPTD the SV aboard, it was stated as follows: 1. accuracy of SVs time synchronization relative to UTC (SU) does not exceed 0,5 μs; 2. accuracy of determining a vector of SVs center-of-mass motion parameters (CMMP) from measurement results does not exceed 100m for coordinates and 0.1 m/s for velocity components. The error estimate as regards the determination of the attitude's parameters is obtained with using a stationary 3-axes turning platform at which the 4-component antenna system is placed. Real-time processing the data on measurements with respect to integral phase of GNSS signal carrier has allowed to provide the measurements of the SVs attitude with an accuracy of about 10 minutes of angle. The estimate of a dynamic error when determining attitude's parameters was carried out using a software imitation complex. The analysis of factors affecting the accuracy of the attitude's determination was performed. Among these factors were dynamics of SVs controlled rotation relative to the center-of-mass, geometric factor, and multipath effect.