Methods of eliminating sources of time errors that affect geodetic observation systems

This article presents a study on the effectiveness of optical synchronization systems in reducing timing errors in high-precision geodetic measurements, particularly within GNSS-based observation methods. The system’s core lies in an opto-microwave phase detector, designed to measure the phase delay between optical and microwave signals precisely. By converting optical signals into electrical ones and achieving continuous phase alignment, the system achieves an exceptionally low drift of 10 fs over several days, ensuring high coherence across time and frequency distribution endpoints. The experimental setup involves two geodetic ground stations located 10–50 km apart, each equipped with GNSS receivers and optical interfaces. A two-way time transfer method via a fiber-optic link synchronizes the stations using a reference atomic clock. The optical system includes a delay-compensated fiber line stabilized through interferometric techniques, with pulse overlap accuracy maintained at 150 fs using a cross-correlator and feedback loop. The stabilizer bandwidth (DC to 1 kHz) mitigates fiber-induced delay fluctuations. Initial synchronization was performed using conventional GPS signals and optical synchronization, enabling a comparative assessment of geodetic accuracy. The results demonstrate a dramatic reduction in time-related errors from nanoseconds to picoseconds and an improvement in coordinate accuracy – error margins were reduced from 22 mm to 7 mm. This indicates that optical synchronization significantly enhances the consistency of observations between remote stations and reduces positioning errors, especially in dynamic applications. The findings confirm that fiber-based optical synchronization offers substantial advantages over traditional radio and satellite-based methods, which are often affected by atmospheric delays, electromagnetic interference, and electronic instabilities. These results support the integration of optical synchronization technologies into regional and global geodetic networks, contributing to advancing next-generation, ultra-precise geodetic systems. Keywords: optical synchronization, geodetic measurements, GNSS, phase detector, fiber optic communication line, time errors.