GPS Multi-stations Networking for Real-Time Subnanosecond Level Time Comparison

Precise point positioning, as a method for high precision time comparison, has the defects of long latency, poor real-time performance and heavy reliance on precise ephemeris and clock products. A new GPS multi-stations networking for real-time time comparison algorithm is proposed. Redundant observations are obviously increased by multi-stations simultaneous surveying. The clock errors of receivers and satellites are simultaneously estimated with the inputs of IGS ultra-rapid ephemeris. Experiments show that, the time difference between proposed algorithm in this paper and IGS final clock products is less than 0.3 ns, and the daily frequency stability of the alignment results is better than 2.5×10^-15.