Accuracy and Precision of USNO GPS Carrier-Phase Time Transfer
Abstract
The United States Naval Observatory (USNO) produces GPS carrier-phase time-transfer (GPSCPTT) estimates for approximately 100 receiver clocks daily. All estimates are available with 16-hr latency; a subset of approximately 34 are available every six hours with three hour latency plus 24 hours of predictions. All can be downloaded immediately after completion from a USNO website. However, despite (or perhaps because of) the continuous nature of this operation, little is known about the precision and accuracy of these estimates. The goal of the work whose results will be presented is to assess the accuracy and precision of these estimates, which (may) constitute a vast, un-tapped resource. Comparison measures available include estimates obtained from two-way satellite time/frequency transfer (TWSTFT), BIPM Circular T, and the International GNSS Service (IGS). At present, it is known that averaged across all satellite and receiver clocks in a solution set, USNO post-processed estimates have an RMS of approximately 130 ps with respect to IGS rapid estimates. However, this is after the removal of a system-wide time and frequency offset. The first six hours of USNO clock predictions have an RMS of approximately 2 ns with respect to IGS rapid estimates, after removal of a time and frequency offset.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 2010
- Accession Number
- ADA546405
Entities
People
- Christine Hackman
- Demetrios N. Matsakis
Organizations
- United States Naval Observatory