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In this paper, the proposed sampling structure based on one-comparator sampling is presented, which can significantly reduce the system clock frequency from 100MHz to 25MHz, so as to reduce chip area. This method is verified by a synchronously-rectified buck converter with a switching frequency of 200kHz, and the digital controller takes as a control kernel the EP1C3T100 FPGA created by Altera Co...
In almost all the studies, the differential receiver calibration and the link calibration had been discussed separately as if the two calibrations were completely independent. In fact, in the sense of the total delay for UTC time transfer, the difference between the receiver and link calibrations is not how to perform the calibration measurement but how to use the measurement data. The two calibration...
In the frame of the BIPM pilot project [8] on the accurate calibration aiming at unifying the UTC time link calibration uncertainties ≤ 2 ns, we studied the instability of the BIPM travelling calibrator (StdB). Using the time stability (Tdev), the closure measurements and the inter-comparison of the two independent receiver systems in the StdB, we analyzed one year data to investigate the short- and...
Accurate GNSS (Global Navigation Satellite System) time transfer needs accurate satellite orbit information. Since Nov. 2009, the GLONASS time transfer is introduced in UTC generation. The precise and timely GLONASS orbit information is indispensable for Circular T computation. In this paper, we compare the GLONASS orbits produced by different analysis centers. We study the differences of the products,...
Precise time transfer is one of the essential works for time-keeping laboratories in maintaining the standards of time and frequency. At the National Metrology Centre (NMC) in Singapore, we have been seeking to improve the time scale performance and time transfer capability by employing different time transfer techniques. Currently, three different time transfer systems are used in the laboratory,...
NTSC (National Time Service Center) is responsible for Chinese national time scale generation and has being applied TWSTFT (two-way satellite time and frequency transfer, TW for short) for time transfer since 1998. NTSC was one of the first UTC laboratories practicing TWSTFT in China. From 2002 to 2004, TWSTFT was the major technique for NTSC contributing to UTC. Since 2007, direct NTSC-European TWSTFT...
The time transfer techniques used to generate TAI are currently the TWSTFT (TW), GPS C/A, and GPS P3. About 19% of all TAI laboratories possess P3, 12% possess TW backed up with P3, i.e., in total only 31% of the TAI laboratories transfer 100% of the primary frequency standards (PFS) including all the Cs fountains and 80% of the total weighted clocks for TAI. GPS carrier phase (CP) data are co-products...
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