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A new time and frequency transfer system compatible with BDS has been developed at NIM, and two of them are in operation at the BIPM since Jan 2017. Experiments with this equipment have been implemented to characterize the time and frequency transfer by BDS. This includes analysis of the satellites signal coverage statistics in the BIPM area, the error correction, the measurement noise of the NIM...
The experiments and results of these calibation campaigns in the frame of APMP from 2014 to 2016 have been reported and the experiment setups and the corresponding delay measurements have been discussed, and the uncertainty has been evaluated for the campaigns.
Two-way Satellite Time and Frequency transfer (TWSTFT) is a primary technique for UTC generation [1]. Only the direct link, the so called UTC link between a Lab(k) and PTB, is used for UTC generation. The numerous redundant links are measured but never used. The concept of the TWSTFT network time transfer has been discussed by several authors [2,3,4,10]. [5,6] are examples of the very first use of...
we proposed a virtual GPS receiver model generated from a multi-receiver ensemble. The time difference between local reference and the realization GPS time (REFGPS) of the virtual receiver is the weighted REFGPS results of all calibrated receivers in ensemble. Depending on the numbers of receivers in ensemble, the measurements of the virtual GPS receiver in each epoch are got from different receivers...
Keyword extraction aims to find representative phrases for a document. Graph-based keyword extraction represent the input document as a graph and rank its nodes according to their score using graph-based ranking method. In this paper, we propose a method to compute importance of co-occurrence word in document and apply it in graph approach to find more representative phrases; introduce words correlation...
Global Positioning System (GPS) carrier-phase (CP) time transfer, as a widely accepted high-precision time transfer method, frequently shows a data-batch boundary discontinuity of up to 1 ns, because of the inconsistency of the phase ambiguities between two consecutive data batches. To eliminate the data-batch boundary discontinuity, several techniques have been proposed in recent years. The question...
In GNSS data reduction, carrier phase (phase) and pseudorange (code) data are complementary. An illustrative example of their interplay is provided, and then it is shown that frequency biases in phase data can be estimated by examination of the difference between the code and phase residuals in Precise Point Positioning (PPP) solutions. Apparent frequency biases, in some cases approaching 0.2 ns/day...
Since 2010 ROA has supported the coordination of the EURAMET Technical Committee for Time and Frequency (TC-TF) Project 1156, a response from EURAMET TC-TF to Recommendation 2 of CCTF 2009: to study the characterization of GNSS equipment in use for establishing the time links between institutes contributing with their clocks to TAI. Starting that year, a GPS calibration campaign was organized between...
Dual-frequency carrier phase and code measurements from geodetic type receivers are a promising tool for frequency and time transfer. In order to use them for clock comparisons, all instrumental delays should be calibrated. We have carried out the calibration of one such receiver, an Ashtech Z12-T type, by two different methods: first, by absolute calibration using a GPS simulator; second, by differential...
Abstract. A new basis godetic network using the GPS technique is now being set up in France. There will be altogether 1000 benchmarks connected to the French levelling network. Obviously, the GPS levelling points are not dense enough to produce a national levelling reference surface. A gravimetrically determined geoid has therefore been proposed to be used for the interpolation between the GPS levelling...
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