Carrier-phase TWSTFT experiments using the ETS-VIII satellite

Nakagawa, Fumimaru; Amagai, Jun; Tabuchi, Ryo; Takahashi, Yasuhiro; Nakamura, Maho; Tsuchiya, Shigeru; Shin'ichi, Hama

doi:10.1088/0026-1394/50/3/200

Cited by 12 publications

(7 citation statements)

References 7 publications

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“…The carrier-phase-based TWsTFT, hereafter called TWsTFT cP, was first tried by Fonville et al [17]; however, it did not become operational. We demonstrated the TWsTFT cP experiment using s-band signals in a test geostationary satellite link [18]. In the experiment, the local signal used for frequency conversion at the satellite was generated from an on-board cesium clock for which the phase was thought to be stable enough for carrier phase measurements.…”

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confidence: 99%

Carrier-phase-based two-way satellite time and frequency transfer

Fujieda

Gotoh

Nakagawa

et al. 2012

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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We performed measurements of carrier-phase-based two-way satellite time and frequency transfer (TWST-FT) with an A/D sampler and conventional TWSTFT system. We found that an instability resulting from a local signal at the satellite transponder was negligible. The short-term stability of 4 × 10(-13) at 1 s was achieved in a short-baseline measurement. The results showed good agreement with the GPS carrier phase.

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confidence: 99%

Carrier-phase-based two-way satellite time and frequency transfer

Fujieda

Gotoh

Nakagawa

et al. 2012

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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“…To compare the new time-frequency standards with the existing time frequency transfer technologies, average longer periods must be conducted. Advanced highprecision CP TWSTFT technology may provide sufficient precision over long distances, but this depends on the availability and reliability of satellite transponders [8]. The time transfer system based on optical fibers uses closed optical fibers as the transmission media; these fibers have the characteristics of high precision and non-interference, with an associated accuracy of such time synchronization better than 0.1 ns [9].…”

Section: Introductionmentioning

confidence: 99%

Comparison of VLBI and GNSS common view for time transfer

Wang¹,

Wang²,

Gao³

et al. 2019

Int. J. Metrol. Qual. Eng.

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With the rapid development of optical clock, the stability and system uncertainty of optical clocks has reached a 1.0e–18 level. Optical clocks will likely constitute the next generation of time-frequency standards for redefining the SI second. Because time and frequency transfer services that rely on satellite systems are not always reliable and currently available technologies are insufficient for comparing the next generation of frequency standards, high-precision time and transfer techniques are strongly desired. Very Long Baseline Interferometry (VLBI) is one of the space geodetic techniques that measure the arrival time delays between multiple stations utilizing radio signals from distant celestial radio sources. Not only can VLBI obtain the angle position measurement of the radio source with sub-millisecond accuracy and the station coordinate measurement with millimeter accuracy, but also, it can provide high-precision information regarding inter-station atomic clock differences. Therefore, it is theoretically feasible to use the VLBI technology to do the remote time transfer. Because of this characteristic of VLBI technology, VLBI has significant application potential in the field of remote time transfer. To confirm the suitability of VLBI to time-frequency transfer for future practical applications, the results of VLBI and GPS common view time transfer were compared using a Kunming-Urumqi baseline. The performance characteristics of time transfer based on VLBI are then analyzed. Experimental results show that VLBI technology can accurately measure the variation of clock differences between stations as same as the GPS common view time comparison technology. It briefly describes the challenges of future VLBI technology for practical applications of time transfer.

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“…Time (epoch) is currently realized and transferred worldwide at the 1--to--30 ns level relative to defined Time Scales by using GPS common view, or GPS carrier--phase, or via Two--Way Satellite Time and Frequency Transfer (TWSTFT) using both code and carrier phase]. 17 , 18 , 19 , 20 With 1 ns timing uncertainty it can take weeks of signal averaging to accurately determine the frequency of the best Cs atomic fountain clocks at national standards labs that have fractional frequency uncertainties of ≈ 2x10 --16 . 21 And if that 1 ns transfer uncertainty could be maintained, it would take over 30 years of signal averaging to compare optical clocks at the now claimed fractional uncertainties of 2x10 --18 -an impractical, meaningless exercise.…”

Section: Introductionmentioning

confidence: 99%

“…Unless a practical time-transfer system can be developed, it is difficult to imagine how the advanced clocks could be put to practical commercial uses. Time (epoch) is currently realized and transferred worldwide at the level of 1-3 ns relative to defined Time Scales by using GPS common view, or GPS carrierphase, or via two-way satellite time and frequency transfer (TWSTFT) using both code and carrier phase [17][18][19][20]. With 1 ns timing uncertainty, it can take weeks of signal averaging to accurately determine the frequency of the best Cs atomic fountain clocks at national standards labs that have fractional frequency uncertainties of ≈ 2×10 −16 [21].…”

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confidence: 99%

Space-time reference with an optical link

Berceau

Taylor

Kahn

et al. 2016

Class. Quantum Grav.

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We describe a method for realizing a high performance Space--Time Reference (STR) using a stable atomic clock in a precisely defined orbit and synchronizing the orbiting clock to high--accuracy atomic clocks on the ground. The synchronization would be accomplished using a two--way lasercom link between ground and space. The basic concept is to take advantage of the highest--performance cold--atom atomic clocks at national standards laboratories on the ground and to transfer that performance to an orbiting clock that has good stability and that serves as a "frequency--flywheel" over time--scales of a few hours. The two--way lasercom link would also provide precise range information and thus precise orbit determination (POD). With a well-defined orbit and a synchronized clock, the satellite could serve as a high--accuracy Space--Time Reference, providing precise time worldwide, a valuable reference frame for geodesy, and independent high--accuracy measurements of GNSS clocks. With reasonable assumptions, a practical system would be able to deliver picosecond timing worldwide and millimeter orbit determination.

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Carrier-phase TWSTFT experiments using the ETS-VIII satellite

Cited by 12 publications

References 7 publications

Carrier-phase-based two-way satellite time and frequency transfer

Carrier-phase-based two-way satellite time and frequency transfer

Comparison of VLBI and GNSS common view for time transfer

Space-time reference with an optical link

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