Uncertainty evaluation of GPS common-view time transfer and frequency stability measurements

2002 ◽  
Author(s):  
Zhongning Dai ◽  
H.A. Chua ◽  
H. Neo
Keyword(s):  
Frequency Stability ◽  
Uncertainty Evaluation ◽  
Time Transfer ◽  
Common View ◽  
Stability Measurements

GNSS time and frequency transfers through national positioning, navigation and timing infrastructure

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Thayathip Thongtan ◽  
Sivinee Sawatdiaree ◽  
Chalermchon Satirapod
Keyword(s):  
Time Scale ◽  
Frequency Stability ◽  
Frequency Offset ◽  
Internal Clock ◽  
Time Transfer ◽  
Time Zone ◽  
Common View ◽  
Standard Format ◽  
Fractional Frequency ◽  
Atomic Time

Abstract GNSS signals have been a practical time transfer tool to realise a Coordinated Universal Time (UTC) and set civilian clocks around the world with respect to this atomic time standard. UTC time scale is maintained by the International Bureau of Weights and Measurements (BIPM) adjusted to be close to a time scale based on the Earth’s rotation. In Thailand, the official atomic time clocks are maintained by the National Institute of Metrology Thailand (NIMT) to produce UTC(NIMT) and Thailand standard time which is always 7 hours ahead of UTC(NIMT) because of the time zone differences between Greenwich and Bangkok. National Positioning, Navigation and Timing (PNT) infrastructure comprises of GNSS geodetic receivers uniformly distributed to continually observe GNSS signals, mainly for geodetic survey applications both real-time and post-processing services. NIMT is involved in order to provide time link to UTC and to determine the characteristics of GNSS receiver internal clocks; namely, fractional frequency offset and frequency stabilities by applying the GNSS time transfer techniques of common-view algorithms. Monitored time differences with respect to UTC(NIMT) are achieved from selected 4 ground stations in different parts of the country with observations of 21 days in order to determine the frequency stability at 1-day and 7-day modes. GNSS standard log files; in RINEX format, at these receivers are transformed into a time transfer standard format; CGGTTS, used to compute the time differences between two stations, the fractional frequency offset and the frequency stability. Averaged fractional frequency offsets are 2.8 × 10 − 13 Hertz/Hertz 2.8\times {10^{-13}}\hspace{2.38387pt}\text{Hertz/Hertz} and computed Allan deviation is around 1.5 × 10 − 13 Hertz/Hertz 1.5\times {10^{-13}}\hspace{2.38387pt}\text{Hertz/Hertz} for an averaging time of 1 day. The comparison of the national time scale and receiver clock offsets of every receivers in this national GNSS PNT infrastructure could be accomplished through common-view time transfer using GNSS satellites to maintain the time link of geodetic active control points to UTC as well as to determine receiver internal clock characteristics.

Comparison of Two-Way and BeiDou Common View Time Transfer between NTSC and BEIJ Station

2014 ◽  
Vol 1049-1050 ◽  
pp. 1997-2000 ◽  
Author(s):  
Hong Zhang ◽  
Min Yan ◽  
Wei Guang
Keyword(s):  
Data Analysis ◽  
Service Center ◽  
Time Transfer ◽  
Time Service ◽  
Common View ◽  
High Agreement ◽  
Frequency Transfer

The data obtained by the two-way satellite time and frequency transfer (TWSTFT) and the BeiDou common view (BDCV) experiments between the National Time Service Center (NTSC) and Beijing station (BEIJ) will be compared in this paper. Results with high agreement between the two techniques will be described. Data analysis results demonstrated that the two-way satellite time and frequency transfer (TWSTFT) and the BeiDou common view (BDCV) can back up each other.

Real-time linked common-view time transfer for monitoring GNSS system time differences

Metrologia ◽  
2012 ◽  
Vol 49 (6) ◽  
pp. 685-695
Author(s):  
Seung-Woo Lee ◽  
Duk Kee Lee ◽  
Young Jae Lee
Keyword(s):  
Real Time ◽  
Time Transfer ◽  
Common View ◽  
System Time
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