Design of a Ku Band Delay Difference Calibration Device for TWSTFT Station

Merck, P.; Achkar, Joseph

doi:10.1109/tim.2004.843328

Cited by 8 publications

(4 citation statements)

References 3 publications

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“…Up to now, it has not been verified that they can be determined with nanosecond accuracy. Nevertheless, the development of station characterization devices is still in progress, and, thus, this problem may be solved in the near future [23,24]. Now we define the calibration value for the link between sites 1 and 2, which contains the terms in curly brackets in equation (3):…”

Section: Theorymentioning

confidence: 99%

Time transfer with nanosecond accuracy for the realization of International Atomic Time

et al. 2008

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Two-way satellite time and frequency transfer (TWSTFT) has become an important technical component in the process of the realization of International Atomic Time. To employ the full potential of the technique, especially for true time transfer, a dedicated calibration is necessary. This consists of the calibration either of the operational link at large, including every component involved, or of the involved ground stations' internal delays only. Both modes were successfully employed by circulating and operating a portable reference station between the sites involved. In this paper, we summarize the theoretical background for the different calibration modes applied and report examples of results from the 13 calibration campaigns performed up to now in Europe and between Europe and the United States. In all of these exercises, estimated uncertainties around 1 ns were achieved. Consecutive campaigns showed a very good reproducibility at the nanosecond level. Additionally, we address and briefly discuss sources that possibly limit the uncertainty for true time transfer employing TWSTFT.

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Section: Theorymentioning

confidence: 99%

Time transfer with nanosecond accuracy for the realization of International Atomic Time

et al. 2008

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“…ε AB and ε BA are the ranging noise. Sending delays τ s A and τ s B and receiving delays τ r A and τ r B can be calibrated onboard with a self-closed loop of transmitting and receiving [19].…”

Section: Inter-satellite Time Comparisonmentioning

confidence: 99%

Joint Timekeeping of Navigation Satellite Constellation with Inter-Satellite Links

Sun

Huang

Gao

et al. 2020

Sensors

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As a system of ranging and positioning based on time transfer, the timekeeping ability of a navigation satellite constellation is a key factor for accurate positioning and timing services. As the timekeeping performances depend on the frequency stability and predictability of satellite clocks, we propose a method to establish a more stable and predictable space time reference, i.e., inter-satellite link time (ISLT), uniting the satellite clocks through inter-satellite links (ISLs). The joint timekeeping framework is introduced first. Based on the weighted average timescale algorithm, the optimal weights that minimize the increment of the ISLT timescale are determined and allocated to the clock ensemble to improve the frequency stability and predictability in both the long and short term. The time deviations with respect to the system time of nine BeiDou-3 satellites through multi-satellite precise orbit determination (MPOD) are used for joint timekeeping evaluation. According to the Allan deviation, the frequency of the ISLT is more stable than the nine satellite clocks in the short term (averaging time smaller than 7000 s), and its daily stability can reach 6 × 10 −15 . Meanwhile, the short-term (two hours) and long-term (10 h) prediction accuracy of the ISLT is 0.18 and 1.05 ns, respectively, also better than each satellite clock. Furthermore, the joint timekeeping is verified to be robust against single-satellite malfunction.

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“…OP is developing an original and rigorous calibration method, based on the satellite simulator equipment and coupled with a faster and accurate measurement process [2]. The main design of the simulator is given in Fig.…”

Section: Progress Work On the Realization Of The Op Twstft Satellimentioning

confidence: 99%

“…The station, calibrated in relative mode in 2004, is officially used for TAI since January 2005. A complete uncertainty budget on the TWSTFT measurements is evaluated giving a combined uncertainty of only 1 ns, and the realization of a satellite simulator based on an original design [2] being in progress. Such a simulator will permit mainly an absolute difference delay calibration of a two-way station.…”

Section: Introductionmentioning

confidence: 99%

Recent time and frequency transfer activities at the Observatoire de Paris

Aclikar

Ubrich

Merck

et al. 2005

Proceedings of the 2005 IEEE International Frequency Control Symposium and Exposition, 2005.

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Important investigations in the time and frequency transfer have been done during the last four years at the Observatoire de Paris (OP). The goal was twofold: improvement of the GPS comparison technique by the use of dual frequency GPS multi-channel receivers in common-views (GPS P3) and the development of a full two-way satellite time and frequency transfer (TWSTFT) station in the Ku-Band.The advantage of the GPS P3 technique is the compensation of the ionospheric delays. The GPS P-Code is transmitted simultaneously on both carriers L1 and L2, and the dualfrequency multi-channel GPS receiver Ashtech Z12-T allows for the so-called P1 and P2 measurements. A simple linear combination gives the ionosphere free P3 measurements. The software developed by the Observatoire Royal de Belgique [1] builds from the geodetic RINEX files such P3 data in the CGGTTS format, and the Common-View method is applied. Due to the availability of several simultaneous Common-Views, a selection can be made which improves the short term frequency stability of the results. A typical result on European baselines gives an Allan Time Deviation σ x (τ) below 200 ps over an analysis period lower than 1 d between H-Masers.The TWSTFT technique, a direct comparison between ground clocks through a communication satellite, is a wellknown technique independent from GPS. In this field, OP developed a full Ku-band two-way station with a dual offset antenna, active up/down-converters and a SATRE modem. The station, calibrated in relative mode in 2004, is officially used for TAI since January 2005. A complete uncertainty budget on the two-way measurement has been evaluated giving a combined uncertainty of only 1 ns. Moreover, the realization of a satellite simulator based on an original design [2] is in progress. Such a simulator will permit mainly an absolute difference delay calibration of a two-way station. During the Primary Frequency Standard comparison done in 2004 over 27-days measurement period, it was observed that H-Masers can be reached at only 0,6 d, with a σ x (τ) = 80 ps on the OP-PTB two-way link.

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Design of a Ku Band Delay Difference Calibration Device for TWSTFT Station

Cited by 8 publications

References 3 publications

Time transfer with nanosecond accuracy for the realization of International Atomic Time

Time transfer with nanosecond accuracy for the realization of International Atomic Time

Joint Timekeeping of Navigation Satellite Constellation with Inter-Satellite Links

Recent time and frequency transfer activities at the Observatoire de Paris

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