T2L2 Flight Model Metrological Performances

Samain, E.; Vrancken, Patrick; Weick, J.; Guillemot, Philippe

doi:10.1109/freq.2007.4319284

Cited by 3 publications

(5 citation statements)

References 8 publications

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“…Progress on satellite-based links may lower the noise floor to the 10 -16 range at one day and advanced space missions such as "ACES" (Atomic Clocks Ensemble in Space) [3] and "T2L2" [4] are being designed to make comparisons in the high 10 -17 at one day. However, even if achieved, such performance would be insufficient for the next generation of optical clocks.…”

Section: Introductionmentioning

confidence: 99%

“…However, both methods are limited by an instability of 10 −15 after one day of averaging time [1] and are consequently insufficient to transfer modern cold atom microwave frequency standards having demonstrated a frequency stability of a few 10 −16 at one day [2]. Progress on satellite-based links may lower the noise floor to the 10 −16 range at one day, and advanced space missions such as Atomic Clocks Ensemble in Space (ACES) [3] and T2L2 [4] are being designed to make comparisons in the high 10 −17 at one day. However, even if achieved, such performance would be insufficient for the next generation of optical clocks.…”

Section: Introductionmentioning

confidence: 99%

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Long-distance frequency transfer over an urban fiber link using optical phase stabilization

et al. 2008

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We transferred the frequency of an ultrastable laser over 86 km of urban fiber. The link is composed of two cascaded 43 km fibers connecting two laboratories, Laboratoire National de Métrologie et d'Essais-Systèmes de Référence Temps-Espace (LNE-SYRTE) and Laboratoire de Physique des Lasers (LPL), in the Paris area. In an effort to realistically demonstrate a link of 172 km without using spooled fiber extensions, we implemented a recirculation loop to double the length of the urban fiber link. The link is fed with a 1542 nm cavity-stabilized fiber laser having a sub-Hz linewidth. The fiber-induced phase noise is measured and cancelled with an all fiber-based interferometer using commercial off-the-shelf pigtailed telecommunication components. The compensated link shows an Allan deviation of a few 10 −16 at one second and a few 10 −19 at 10,000 seconds.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Long-distance frequency transfer over an urban fiber link using optical phase stabilization

et al. 2008

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“…M SF is computed from the transmission of the spectral filter (FWHM = 10 nm), from the attenuation generated by the lenses and from the solar spectrum. The albedo is given by Al = (157U CW T 0 ) / (M SF I ) , (5) with M SF = 19 W m −2 .…”

Section: Background Optical Power Flux Measurementmentioning

confidence: 99%

“…T2L2 was specified to realize time transfers with stability better than 1 ps over 1000 s and accuracy better than 100 ps. These performances are based on the metrology used inside the laser station and also on the T2L2 space instrument [5]. Particular care has been taken during the design and the manufacturing of the instrument to meet these metrological requirements.…”

Section: Introductionmentioning

confidence: 99%

Time transfer by laser link (T2L2): characterization and calibration of the flight instrument

Samain

Vrancken

Guillemot³

et al. 2014

Metrologia

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The T2L2 project (time transfer by laser link) allows for the synchronization of remote ultra-stable clocks over intercontinental distances (Fridelance et al 1997 Exp. Astron. 7, Samain and Fridelance 1998 Metrologia 35 151–9). The principle is derived from satellite laser ranging technology with dedicated space equipment designed to record arrival times of laser pulses at the satellite. The space segment has been launched in June 2008 as a passenger experiment on the ocean altimetry satellite Jason 2. T2L2 had been specified to yield a time stability of better than 1 ps over 1000 s integration time and an accuracy of better than 100 ps. This level of performance requires a rigorous data processing which can be performed only with a comprehensive calibration model of the whole instrumentation. For this purpose, several experimental measurements have been performed before and during the integration phase of the T2L2 space instrument. This instrument model is one of the cornerstones of the data reduction process which is carried out to translate the raw information to a usable picosecond time transfer. After providing a global synopsis of the T2L2 space instrument, the paper gives a description of the experimental setup for the instrument characterization. It then details the different contributions within the calibration model and concludes with an applied example of a space to ground time transfer.

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“…The current state-of-the-art for ground-to-space laser time-transfer is the Time-Transfer by Laser Link (T2L2) [11]. Extensive data processing confirmed the T2L2 approach's accuracy of 100 picoseconds and stability of more than 1 picosecond over 1000 s [12]. Moreover, an increasing number of NEO (Near-Earth Orbit) satellites will integrate onboard clocks [13], while the establishment of LEO-MEO (Low Earth Orbit-Medium Earth Orbit) constellations will facilitate bidirectional laser connections [14].…”

Section: Introductionmentioning

confidence: 99%

Improved Simulated Annealing Algorithm on the Design of Satellite Orbits for Common-View Laser Time Transfer

Xue,

Zhang,

Deng

et al. 2024

Remote Sensing

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Laser Time Transfer (LTT) has proven to be able to improve remote time transfer accuracy compared to microwave technology. The impact of satellite clock errors and atmospheric delays during LTT will be further reduced in the common-view mode. The challenge is presented as an optimization problem that is limited by satellite trajectories. This paper introduces an improved simulated annealing algorithm designed to maximize the common-view possibility among various station pairs within regional Satellite Laser Ranging (SLR) networks by optimizing satellite orbit trajectories. The study proposes a system model that integrates LTT principles with satellite visibility considerations. The simulated annealing algorithm is improved with new annealing strategies that incorporate control strategies, and modify the cooling function. Comparative simulation analyses demonstrate the effectiveness of the algorithm, resulting in a significant reduction in computation time by over 10 times. The optimized orbits exhibit common-view windows between 3.337 and 8.955 times longer than existing orbits. Further simulations are conducted to optimize the orbits, and common-view models are established for 45 pairs among 10 stations. The optimizations result in common-view times ranging from 6.183 to 60.633 min in the Asia-Pacific region and from 5.583 to 61.75 min in the Europe-to-Asia region. This can provide valuable references for designing satellite constellations.

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T2L2 Flight Model Metrological Performances

Cited by 3 publications

References 8 publications

Long-distance frequency transfer over an urban fiber link using optical phase stabilization

Long-distance frequency transfer over an urban fiber link using optical phase stabilization

Time transfer by laser link (T2L2): characterization and calibration of the flight instrument

Improved Simulated Annealing Algorithm on the Design of Satellite Orbits for Common-View Laser Time Transfer

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