A frequency-domain view of time-domain characterization of clocks and time and frequency distribution systems

Allan, David W.; Weiss, Marc A.; Jespersen, J.L.

doi:10.1109/freq.1991.145966

Cited by 84 publications

(61 citation statements)

References 13 publications

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“…These data were then used to calculate the Allan standard deviation and RMS time error. For a description of the Allan standard deviation, see (Allan et al, 1991). Results appear in Figures 4 and 5.…”

Section: Resultsmentioning

confidence: 97%

Local Oscillator Distribution Using A Geostationary Satellite

2004

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A satellite communication system suitable for distribution of local oscillator reference signals for a widely spaced microwave array has been developed and tested experimentally. The system uses a round-trip correction method to remove effects of atmospheric fluctuations and radial motion of the satellite. This experiment was carried out using Telstar-5, a commercial Ku-band geostationary satellite. A typical Ku-band satellite has uplink and downlink capacity at 14-14.5 GHz and 11.7-12.2 GHz, respectively. For this initial experiment, both earth stations were located at the same site to facilitate direct comparison of the received signals. The local oscillator reference frequency was chosen to be 300 MHz and was sent as the difference between two Ku-band tones. The residual error after applying the round trip correction has been measured to be better than 3 ps for integration times ranging from 1 to 2000 s. For integration times greater than 500 s, the system outperforms a pair of hydrogen masers with the limitation believed to be ground-based equipment phase stability. The idea of distributing local oscillators using a geostationary satellite is not new; several researchers experimented with this technique in the eighties, but the achieved accuracy was 3 to 100 times worse than the present results. Since then, the cost of both leased satellite bandwidth and the Ku-band ground equipment has dropped substantially and the performance of various components has improved. An important factor is the availability of narrow bands which can be leased on a communications satellite. We lease three 100 kHz bands at approximately one hundredth the cost of a full 36 MHz-wide transponder. Further tests of the system using terminals separated by large distances and comparison tests with two hydrogen masers and radio interferometry of astronomical objects are needed.

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Section: Resultsmentioning

confidence: 97%

Local Oscillator Distribution Using A Geostationary Satellite

2004

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“…of the environmental and inherent frequency drift, meaning that the average <yi> may drift with time, and the calculation will not converge with time and/or increasing number of samples. This is why D. Allan introduced the so called Allan variance [22], defined by the following equation: 1 2 ⁄ 〈 〉 The Allan variance removes drift and is able to converge under many conditions. Such analysis provides information on the shape of the noise contribution, and linear "asymptotic" fit in terms of σy 2 (τ) = Σ kµ.τ µ can be used to define the noise behavior.…”

Section: Time Transfer Noise Analysis Toolsmentioning

confidence: 99%

Ns-level time transfer over a microwave link using the PTP-WR protocol

Rico

Aubry

Botteron

et al. 2015

2015 Joint Conference of the IEEE International Frequency Control Symposium &Amp; The European Frequency and Time Forum

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Abstract-today it is possible to achieve sub-ns level time synchronization on a wireline network while only us-level synchronization can be achieved on a wireless (microwave) link. In this paper we will, first, study the performances of different time synchronization wireline based protocols, such as Precision Time Protocol (PTP), Synchronous Ethernet (SyncE) and PTP White Rabbit (PTP-WR). And then, we will present our results using a wireless link, and determine which radio technology can achieve ns range time synchronization. Our motivation is to qualify a time transfer process operating over microwave link and offering secured GNSS-like time performance.

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“…1). Even though the data are unevenly spaced, we compute TDEV [9] of the results by using the average minimum spacing, i.e. the last reference time minus the first, divided by the number of data intervals (Fig.…”

Section: Report Documentation Pagementioning

confidence: 99%

A comparison of GPS common-view time transfer to all-in-view

Weiss

Petit

Jiang

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

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Abstract-All-in-view time transfer is being considered to replace common-view for computing the links of International Atomic Time (TAI). The components in all-in-view GPS time transfer that do not cancel as they do in the common-view technique are the satellite clock estimate and the ephemeris estimate. We show that these components average down as white phase noise with a typical level of 2 ns with 13 minute averaging,and under 100 ps at 1 d. Looking at closures including stations in Europe, North America and Japan, we see evidence for a white PM level below 0.5 ns with an averaging time of 1 d, a flicker floor of 100 ps after 3 d, and systematic effects at a level of up to 1 ns. We also show evidence that errors in ionospheric maps and multi-path interference can cause noise processes at least as dispersive as flicker phase noise at 300 ps from 1 d to past 10 d. We conclude that all-in-view GPS time transfer improves stability over common-view for links as long as 5000 km, and is equivalent for links as short as 2500 km. We also find that ionosphere-free time transfer data may provide a significant improvement for averaging past 1 d.

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A frequency-domain view of time-domain characterization of clocks and time and frequency distribution systems

Cited by 84 publications

References 13 publications

Local Oscillator Distribution Using A Geostationary Satellite

Local Oscillator Distribution Using A Geostationary Satellite

Ns-level time transfer over a microwave link using the PTP-WR protocol

A comparison of GPS common-view time transfer to all-in-view

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