GNSS Timing Performance Assessment and Results Analysis.

Area of Science:

• * Geodesy and Geomatics
• * Satellite Navigation and Timing

Background:

• * Global Navigation Satellite Systems (GNSS) provide essential timing services with individual performance specifications.
• * A uniform methodology for assessing GNSS timing performance is currently lacking.
• * Existing GNSS timing assessments lack standardized comparison metrics.

Purpose of the Study:

• * To analyze timing performance specifications for major GNSS.
• * To propose a uniform assessment methodology for GNSS timing performance, focusing on time transfer accuracy.
• * To evaluate and compare the timing performance of multiple GNSS.

Main Methods:

• * Analysis of timing performance specifications for BDS, GPS, GLONASS, and Galileo.
• * Development of an assessment method for Coordinated Universal Time (UTC) using BIPM and NTSC references.
• * Calculation of the uncertainty budget for the proposed assessment method.

Main Results:

• * In 2021, GNSS time transfer accuracy was: BDS (13.8 ns), GPS (4.5 ns), GLONASS (16.8 ns), and Galileo (4.2 ns).
• * All assessed GNSS met their specified timing requirements (30 ns or 40 ns).
• * GPS and Galileo significantly exceeded performance requirements, while BDS and GLONASS indicated potential for improvement.

Conclusions:

• * The proposed assessment method provides a uniform approach to evaluating GNSS timing performance.
• * GPS and Galileo demonstrate superior time transfer accuracy compared to BDS and GLONASS.
• * Further improvements in BDS and GLONASS timing are possible, especially if local user reference times align with UTC.