Geodetic techniques for time and frequency comparisons using GPS phase and code measurements

Ray, Jim; Senior, K.

doi:10.1088/0026-1394/42/4/005

Cited by 145 publications

(82 citation statements)

References 42 publications

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“…These files give the geocentric coordinates and clock values for each satellite tabulated at 15-minute intervals and are based on a weighted combination of analyses by several independent groups using dual-frequency pseudorange and carrier phase data from a globally distributed tracking network. For background, Ray and Senior (2005) have reviewed geodetic methods for GPS time and frequency comparisons. The IGS combination procedures were improved and the clock products were densified to 5-minute samples beginning in November 2000 (Kouba and Springer 2001).…”

Section: Introductionmentioning

confidence: 99%

Characterization of periodic variations in the GPS satellite clocks

2008

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Standard Form 298 (Rev. 8-98)Prescribed by ANSI Std. Z39.18Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. The clock products of the International Global Navigation Satellite Systems (GNSS) Service (IGS) are used to characterize the timing performance of the GPS satellites. Using 5-minute and 30-second observational samples and focusing only on the sub-daily regime, approximate power-law stochastic processes are found. The Block IIA Rb and Cs clocks obey predominantly random walk phase (or white frequency) noise processes. The Rb clocks are up to nearly an order of magnitude more stable and show a flicker phase noise component over intervals shorter than about 100 s. Due to the onboard Time Keeping System in the newer Block IIR and IIR-M satellites, their Rb clocks behave in a more complex way: as an apparent random walk phase process up to about 100 s then changing to flicker phase up to a few thousand seconds. Superposed on this random background, periodic signals have been detected in all clock types at four harmonic frequencies, n × (2.0029 ± 0.0005) cycles per day (24 hr UTC), for n =1, 2, 3, and 4. The equivalent fundamental period is 11.9826 ± 0.0030 hours, which surprisingly differs from the reported mean GPS orbital period of 11.9659 ± 0.0007 hours by 60 ± 11 s. We cannot account for this apparent discrepancy but note that a clear relationship between the periodic signals and the orbital dynamics is evidenced for some satellites by modulations of the spectral amplitudes with eclipse season. All four harmonics are much smaller for the IIR and IIR-M satellites than for the older blocks. Awareness of the periodic variations can be used to improve the clock modeling, including for interpolation of tabulated IGS products for higher-rate GPS positioning and for predictions in real-time applications. This is especially true for high-accuracy uses, but could also benefit the standard GPS operational products. The observed stochastic properties of each satellite clock type are used to estimate the growth of interpolation and prediction errors with time interval. REPORT TYPE 1. REPORT DATE (DD-MM-YYYY) TITLE AND SUBTITLE AUTHOR(S) PERFORMING ORGANIZATION REPORT NUMBER PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) SPONSOR / MONITOR'S ACRONYM(S) 9. SPONSORING / MONITORING AGENCY NAME(S) AND ADDRESS(ES) SPONSOR / MONITOR'S REPORT NUMBER(S)

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Section: Introductionmentioning

confidence: 99%

Characterization of periodic variations in the GPS satellite clocks

2008

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“…As we can observe in the figure, the jumps are rarely mitigated and large jumps are transferred to the next in the case of using 2 successive jumps while most of the jumps are reduced more or less by using 3 successive jumps. The absolute synchronization error between two clocks is obtained from the code measurement data (Ray & Senior 2005). Therefore, it is expected that the jumps can be somewhat abated with the assistance of P3 data.…”

Section: Measurement Resultsmentioning

confidence: 99%

Evaluation of Daily Jump Compensation Methods for GPS Carrier Phase Data

Lee¹,

Yang²,

Lee³

et al. 2015

Journal of Positioning, Navigation, and Timing

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In this paper, we described the timing-offset comparison results between various daily jump compensation methods for GPS carrier phase (CP) measurement data. For the performance comparison, we used about 70 days GPS measurement data obtained from two GPS geodetic receivers which share the reference 1 PPS and RF signals and closely located in each other within a few meters. From the experiment results, the followings were observed. First, daily jumps existed in CP measurements depend on not only the environment but also the receiver which will make a full compensation be very hard or impossible. Second, clock bias can be occurred in the case of using a simple compensation with accumulation of daily jumps but it could be used in a short-period frequency comparison campaign (less than about 7 days) despite of its drawback.

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“…Considering the frequency difference of UTC(NIM) and SI-second, the Hydrogen maser we used for frequency measurement can be calibrated. After the calculation with the GPS precise point positioning (PPP) technique [26], we achieved a frequency transfer uncertainty of ~1×10 -14 with an averaging time of one day. Fig.…”

Section: Camentioning

confidence: 99%

Hertz-level measurement of the40Ca+4s
Huang
¹
,
Cao
²
,
Liu
³

et al. 2012
Phys. Rev. A
60
0
42
0
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We report a frequency measurement of the clock transition of a single 40 Ca + ion trapped and laser cooled in a miniature ring Paul trap with 10 -15 level uncertainty. In the measurement, we used an optical frequency comb referenced to a Hydrogen maser, which was calibrated to the SI second through the Global Positioning System (GPS). Optical frequency standards have been developed rapidly in recent years thanks to the development of the cold atoms, the optical frequency comb technology [1,2] and the ultra-narrow-linewidth lasers. Optical frequency standards are expected to replace the Cs primary microwave standard as in the definition of the SI second in the near future. The measurement of the absolute optical frequency for the clock transition is an important step in the development of the optical frequency standards based on single ions and ultracold neutral atoms. The clock transition frequency had been measured using the optical frequency comb referenced to the Cs fountain and using GPS as a link to the SI second without a primary standard for direct calibration. The clock transition frequency had been measured referenced to the Cs fountain at uncertainties on the order of 10 level, which was referenced to the Cs atomic fountain clock [13].In this paper, we report on the first measurements of the 40 Ca + 4s 2 S 1/2 -3d 2 D 5/2 transition frequency with an uncertainty level of 10 -15 using an optical frequency comb referenced to a Hydrogen maser, which was calibrated through the Global Positioning System (GPS) as a link to the SI second. To approach a measurement of 10 -15 level accuracy, we performed the measurement for a very long time (7×10 5 s in May and 1.5×10 6 s in June) to reduce the statistical error and the frequency transfer error. At the same time, the systematic error had been reduced to be smaller than the previous work [14] by achieving the lower ion temperature and increasing the measurement precision on the electric quadrupole shift. Figure 1 is a schematic diagram of our experimental setup. Full details of the laser cooling, trapping detecting and probing system including the locking scheme of probe laser to the ion transitions used in this work were reported in previous works [14][15][16][17]. Briefly, a single 40 Ca + ion was trapped and cooled in a miniature Paul ring trap. The trap had an endcap-to-center distance of z 0  0.6mm with a center-to-

show abstract

Geodetic techniques for time and frequency comparisons using GPS phase and code measurements

Cited by 145 publications

References 42 publications

Characterization of periodic variations in the GPS satellite clocks

Characterization of periodic variations in the GPS satellite clocks

Evaluation of Daily Jump Compensation Methods for GPS Carrier Phase Data

Hertz-level measurement of the40Ca+4s
Huang
¹
,
Cao
²
,
Liu
³

et al. 2012
Phys. Rev. A
60
0
42
0
View full text Add to dashboard Cite

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Geodetic techniques for time and frequency comparisons using GPS phase and code measurements

Cited by 145 publications

References 42 publications

Characterization of periodic variations in the GPS satellite clocks

Characterization of periodic variations in the GPS satellite clocks

Evaluation of Daily Jump Compensation Methods for GPS Carrier Phase Data

Hertz-level measurement of the40Ca+4sHuang1, Cao2, Liu3 et al. 2012Phys. Rev. A600420View full textAdd to dashboardCite

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About

Hertz-level measurement of the40Ca+4s
Huang
¹
,
Cao
²
,
Liu
³

et al. 2012
Phys. Rev. A
60
0
42
0
View full text Add to dashboard Cite