GNSS Carrier-Phase Network Time and Frequency Transfer Technique

Ivan Skakun, Vladimir Mitrikas

Peer Reviewed

Abstract:	High-precision time and frequency transfer methods, which are based on Global Positioning System (GPS) carrier-phase, are widely accepted. These methods provide much lower short-term noise than other time and frequency transfer methods, such as Two Way Satellite Time and Frequency Transfer (TWSTFT) and Common-View (CV) Time and Frequency Transfer. However, carrier-phase time and frequency transfer solutions frequently show day boundary discontinuity of up to 1 ns due to the inconsistency of the phase ambiguity between two independent processing time intervals. There are several methods, which have been proposed in recent years to eliminate this problem: RINEX-shift method, Integer CV and others. The Integer CV is similar to the GPS Common-View time transfer, but using phase rather than code with integer ambiguity resolution. The advantages of this method are as follows: it cancels out the common errors from satellites and path; the integer ambiguity resolution makes it more likely to be insensitive to small noise. However, there are some disadvantages: it does not work well for a long baseline because of few common-view GPS satellites and no common path and errors in calculated range modeling can lead to frequency estimation errors. Network time and frequency transfer technique, which aims to overcome the disadvantages highlighted above has been researched. The processing based study was completed by investigating the profit for time and frequency transfer when introducing the integer carrier-phase ambiguities. The bottom line of this method is the network processing of a number of stations, which pairwise have few common-view satellites. Code and phase measurements of GPS and GLONASS satellites are used. The advantage is the estimation of phase clock difference on long baselines by using carrier-phase ambiguities integer nature. The results from the present time and frequency solution are shown in comparison to results obtained with independent time and frequency techniques.
Published in:	Proceedings of the 28th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2015) September 14 - 18, 2015 Tampa Convention Center Tampa, Florida
Pages:	3491 - 3496
Cite this article:	Skakun, Ivan, Mitrikas, Vladimir, "GNSS Carrier-Phase Network Time and Frequency Transfer Technique," Proceedings of the 28th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2015), Tampa, Florida, September 2015, pp. 3491-3496.
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