Bipm Report

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Rapport BIPM-2004/06 BUREAU INTERNATIONAL DES POIDS ET MESURES DETERMINATION OF THE DIFFERENTIAL TIME CORRECTIONS FOR GPS TIME EQUIPMENT LOCATED AT THE OP, PTB, AOS, KRISS, CRL, NIST, USNO and APL W. Lewandowski and L. Tisserand 2004 Pavillon de Breteuil, F-92312 SEVRES Cedex 1 Abstract The BIPM continues a series of differential calibrations of GPS equipment located in time laboratories contributing to TAI. This report details measurements which took place from 13 August 2003 to 11 February 2004, involving GPS time equipment located at the Observatoire de Paris (OP, Paris, France), the Physikalisch-Technische Bundesanstalt (PTB, Braunschweig, Germany), the Astrogeodynamical Observatory Space Research Centre P.A.S. (AOS, Borowiec, Poland), the Korea Research Institute of Standards and Science (KRIS, Daejeon, Rep. Of Korea), the Communications Research Laboratory (CRL, Tokyo, Japan), the National Institute of Standards and Technology (NIST, Boulder, USA), the U.S. Naval Observatory (USNO, Washington D.C., USA) and the Applied Physics Laboratory (APL, Laurel, Mass., USA). INTRODUCTION The BIPM is conducting a series of differential calibrations of GPS equipment located in time laboratories contributing to TAI. As for previous trips the GPS time equipment located at the OP was chosen as reference: to check the reproducibility of the measurements, the calibrations were organized as round trips beginning and ending at the OP. It has often served in the past as reference laboratory for GPS calibrations. Over the last twenty years its GPS time receiver has been compared several times with the NIST absolutely-calibrated reference GPS time receiver. The difference between these two has never exceeded a few nanoseconds. Repeated determinations of the differential time corrections for the GPS time equipment located in the various laboratories should: • improve the accuracy of the access to UTC of participating laboratories; • provide valuable information about the stability of GPS time equipment; • serve as provisional differential calibrations of the two-way equipment at the laboratories. This report details an exercise which took place from 13 August 2003 to 11 February 2004. Succeeding visits are scheduled to take place at four to five month intervals. 2 EQUIPMENT Details of the receivers involved are provided in Table 1. More information about the set-up of equipment at each location is provided in Appendix I. Table 1. GPS equipment involved in this comparison. Laboratory OP PTB AOS KRIS CRL NIST USNO APL BIPM portable receiver Receiver Maker AOA AOA AOS CSIRO NML JAVAD NIST AOS SRC TFS-NPL AOS Receiver Type TTR-5 TTR-5A TTS-2 Topcon Euro-80 L1/L2 Euro-80 TTR-5 TTS-2 GPSCV TTS-2 Receiver Ser. No 051 156 023 023C10474 8PN45EETDKW NBS10 014 TFS112 028 The portable BIPM receiver is equipped with a C123 cable. Its delay measured at the BIPM is 178.8 ns with a standard deviation of 0.4 ns. This delay was measured using a double-weight pulse method with a time interval counter steered by an external frequency source (an Active Hydrogen Maser CH1-75, KVARZ). We measured at the very beginning of the linear part of the rising pulse at each end of the cable using a 0.5 V trigger level [1]. The delay of this cable was also measured at the visited laboratories. The results are reported in Appendix II. CONDITIONS OF COMPARISON For the present comparison, the portable equipment comprised the receiver, its antenna and a calibrated antenna cable. The laboratories visited supplied: (a) a 10 MHz reference signal; and (b) a series of 1 s pulses from the local reference, UTC(k), via a cable of known delay. In each laboratory the portable receiver was connected to the same clock as the local receiver and the antenna of the portable receiver was placed close to the local antenna. The differential coordinates of the antenna phase centres were known at each site with standard uncertainties (1σ) of a few centimetres. 3 RESULTS The processing of the comparison data obtained in laboratory k consists first of computing, for each track i, the time differences: dtk,i=[UTC(k) – GPS time]BIPM,i – [UTC(k) – GPS time]k,i . The noise exhibited by the time series dtk is then analysed, for each of the laboratories visited, by use of the modified Allan variance. In each case, white phase noise was exhibited up to an averaging interval of about one day. We illustrate this in Figure 1. Figure 1. Square root of the modified Allan variance of the time series dtOP for the period: 02 February 2004 to 11 February 2004. The one-day averages are reported in Figure 2 and Appendix III. The level of noise for oneday averaging period is reported in Table 2. 4 dtk/ns [REF(Labk)-(GPS TIME)] BIPM -[REF(Labk)-(GPS TIME)] Labk Figure 2. Daily averages of dtk,i for each laboratory k (see Appendix III). Next, we computed mean offsets for the full duration of comparison at each location, and the corresponding standard deviations of individual common view measurements (see Table 2). Table 2. Mean offsets for the full duration of the comparison at each location. Lab Period Total Mean Standard Level of number of offset deviation of noise common /ns individual for 1 day views common view /ns observations /ns OP 13/08 -18/08/03 197 -9.70 3.69 0.4 Dispersion of daily mean /ns 0.79 PTB 27/08 - 01/09/03 199 -9.42 3.13 0.6 0.71 AOS 26/09 - 01/10/03 2108 18.93 1.82 0.2 0.24 KRIS 22/10 - 28/10/03 1641 -0.69 2.37 0.1 0.29 CRL 07/11 - 11/11/03 1149 -4.77 3.37 0.5 0.59 NIST 26/11 - 08/12/03 541 -14.16 3.18 0.3 0.51 USNO 16/12 - 23/12/03 3675 -7.12 2.63 0.1 0.18 APL* 23/12 - 29/12/03 3048 -16.07 0.61 0.4 0.11 OP 02/02 - 11/02/04 363 -9.35 2.81 0.3 0.55 *Note: At the APL local and visiting receivers were connected to the same antenna. 5 The “closure” – the difference between the first and last sets of measurements made at the OP – was within one nanosecond, which is an excellent result.. After averaging the results of the two sets of measurements at the OP, we then derived differential time corrections which should be made (added) to time differences derived during the GPS comparisons of the time scales kept by the laboratories. The results are summarized in Table 3. Table 3. Differential time correction d to be added to[UTC(k1) – UTC(k2)], and its estimated uncertainty u(d) for the period of comparison (1σ). d/ns [UTC(k1)-UTC(k2)] [UTC(PTB)-UTC(OP)] [UTC(AOS)-UTC(OP)] [UTC(KRIS)-UTC(OP)] [UTC(CRL)-UTC(OP)] [UTC(NIST)-UTC(OP)] [UTC(USNO)-UTC(OP)] [UTC(APL)-UTC(OP)] +0.1 +28.5 +8.8 +4.8 -4.6 +2.4 -6.5 u(d)/ns 3.0 3.0 3.0 3.0 3.0 3.0 3.0 The uncertainties given in this table are conservative. They are mainly driven by the uncertainty due to the ‘round-trip’ reproducibility at the OP. For information we provide in Table 4 results of some past calibrations between NIST and OP. Table 4. Some past calibrations between NIST and OP: d are differential time corrections to be added to [UTC(NIST)-UTC(OP)], and u(d) are estimated uncertainties for the periods of comparisons. Date July 1983 January 1985 September 1986 October 1986 January 1988 April 1988 March 1995 May 1996 May 2002 July 2003 December 2003 d/ns 0.0 –7.0# 0.7* –1.4* –3.8* 0.6* –3.7* –0.7* –5.0* –5.6* -4.6* # NBS03 receiver at NIST * NBS10 receiver at NIST u(d)/ns 2.0 13.0 2.0 2.0 3.0 3.0 1.0 1.5 3.0 1.9 3.0 Reference [2] [3] [4] [4] [5] [6] [7] [8] [9] [10] [11] 6 CONCLUSION These measurements are part of a series of differential calibrations of GPS equipment located time laboratories contributing to TAI. They improve accuracy of the access to UTC of participating laboratories. The present measurements were performed under good conditions with a very good closure of travelling equipment at the OP. The GPS time equipment of most of participating laboratories agrees within a few nanoseconds with reference equipment at the NIST and the OP. At the AOS the offset is large, but this was already well known before. The GPS time equipment located at the NIST and the OP are excellent references for GPS calibration trips. This equipment was compared several times during the past two decades. The differences between them have never exceeded a few nanoseconds (see Table 4). The next trip involving the some of visited laboratories is scheduled for 2004. Acknowledgements The authors wish to express their gratitude to their colleagues for unreserved collaboration they received. Without this, the work could not have been accomplished. REFERENCES [1] G. de Jong, "Measuring the propagation time of coaxial cables used with GPS receivers," Proc. 17th PTTI, pp. 223-232, December 1985. [2] D. Allan, D. Davis, M.A. Weiss, Personal communication, 1983. [3] J. Buisson, Personal communication, 1985. [4] W. Lewandowski, M. A. Weiss, "A Calibration of GPS Equipment at Time and Frequency Standards Laboratories in the USA and Europe", Metrologia, 24, pp. 181186, 1987. [5] BIPM Calibration Certificate of 19 January 1988. [6] BIPM Letter of 15 June 1988, BG/9G.69. [7] M.A. Weiss, "Calibration of OP Receiver AOA51 Against NIST Receiver NBS10" March 1995. [8] M.A. Weiss, "Calibration of OP Receiver AOA51 Against NIST Receiver NBS10" March 1996. [9] W. Lewandowski, P. Moussay, "Determination of the differential time corrections for GPS time equipment located at the OP, IEN, ROA, PTB, NIST, and USNO", BIPM Report -2002/02, July 2002. [10] M.A. Weiss, "Calibration of OP Receiver AOA51 Against NIST Receiver NBS10" July 2003. [11] This Report. 7 Appendix I Set-ups of local and portable equipment at each location (forms completed by the participating laboratories) 8 9 BIPM GPS calibration information sheet BNM – SYRTE, Observatoire de Paris Laboratory: Date and hour of the beginning of measurements: 13 August 2003 Date and hour of the end of measurements: 18 August 2003 Receiver setup information Local: NBS 51 Allen Osborne Associates • Maker: TTR-5 • Type: 051 • Serial number: • Receiver internal delay (GPS) : 54 ns • Receiver internal delay (GLO) : 505 IF • Antenna cable identification: Corresponding cable delay : 168 ns ± 0,3 ns 503 • UTC cable identification: Corresponding cable delay : Delay to local UTC : 304 ns 0.5 V • Receiver trigger level: ITRF • Coordinates reference frame: Latitude or X m 4 202 780,30 m Longitude or Y m 171 370,03 m Height or Z m 4 778 660,12 m Portable: BIPM K AOS TTS-2 S/N 028 0.0 (not calibrated) C123 178,78 ns ± 0,4 ns 497 306 ns 0.5 V ITRF 4 202 783,64 m 171 367,43 m 4 778 657,38 m Antenna information Local: A.O.A. - Portable: ITR TSA-2 GPS 3-072002 • Maker: • Type: • Serial number: If the antenna is temperature stabilised • Set temperature value : - Local antenna cable information • Maker: • Type: • Is it a phase stabilised cable: • Length of cable outside the building : / RG-58 No Approximately 6 meters General information • Rise time of the local UTC pulse: • Is the laboratory air conditioned: • Set temperature value and uncertainty : • Set humidity value and uncertainty : 4 ns Yes (21,5 ± 2) °C / Cable delay control Cable identification BIPM C123 delay measured by BIPM 178,78 ns ± 0,4 ns Delay measured by local method 179,9 ns ± 0,3 ns 10 Plot of the experiment set-up: Link to the local UTC of both receivers and Antenna positions HP 5071 A Cs clock antenna antenna 5 MHz IF TST 6490 Micro phase stepper LO 10 MHz 5 MHz NBS51 BIPMK TTS-2 HP 5087 A Freq distribution amplifier HP 5087 A Freq distribution amplifier 5 MHz 1 pps 10 MHz 1 pps 5 MHz TST 6460 Digital clock 1 pps TST 6473 Pulse distribution amplifier 1 pps Reference point UTC(OP) HP 5370B TIC Description of the local method of cable delay measurement: 10 MHz H maser 10 MHz H maser 10 MHz H maser TST 6460 Digital clock H maser 1 PPS TST 6460 Digital clock 1 PPS 1 PPS H maser TST 6460 Digital clock H maser 1 PPS 1 PPS 1 PPS B A B Tested cable A B Tested cable A START HP 5370 B STOP TIC Step 1, 3, 5 START HP 5370 B TIC STOP START Step 2 HP 5370 B TIC Step 4 The method used to calibrate the cables is a double wheight method in five steps as shown above. At each step (i) the TIC gives the result (Ri)of 100 measurments. The test cable delay is then obtained by the following formula:  R + R3   R3 + R5  R2 − 1  − R4 + 2   2   Delay = + corrections 2 The corrections are the estimated delay introduced by adaptators : - 0,1 ns / adaptator STOP 11 BIPM GPS calibration information sheet Laboratory: PTB Date and hour of the beginning of measurements: 2003-08-27 06:34 UTC Date and hour of the end of measurements: 2003-09-01 06:30 UTC Receiver setup information Local: AOA • Maker: TTR-5A • Type: S/N 0156 • Serial number: • Receiver internal delay (GPS) : 58.0 ns • Receiver internal delay (GLO) : • Antenna cable identification: Corresponding cable delay : 215 ns (entered (215+23) ns) • UTC cable identification: Corresponding cable delay : Delay to local UTC : -23 ns (entered 0 ns) 0.5 V • Receiver trigger level: ITRF • Coordinates reference frame: Latitude or X m +3844066.36 m Longitude or Y m +709657.18 m Height or Z m +5023125.00 m Portable: BIPM K AOS TTS-2 S/N 028 0.0 (not calibrated) C123 178.78 ns ± 0.4 ns 96.7 ns ± 0.2 ns 0.5 V ITRF +3844064.47 m +709657.61 m +5023126.50 m Antenna information Local: AOA NIST-Type - • Maker: • Type: • Serial number: If the antenna is temperature stabilised • Set temperature value : Portable: ITR TSA-2 GPS 3-072002 - Local antenna cable information • Maker: • Type: • Is it a phase stabilised cable: • Length of cable outside the building : Air Dielectric Cables ? no about 30 m General information • Rise time of the local UTC pulse: • Is the laboratory air conditioned: • Set temperature value and uncertainty : • Set humidity value and uncertainty : 5 ns yes (23 ± 1) °C max. 50 % RF Cable delay control Cable identification BIPM C123 delay measured by BIPM 178.78 ns ± 0.4 ns Delay measured by local method 178.5 ns ± 0.2 ns 12 Plot of the experiment set-up: Link to the local UTC of both receivers and Antenna positions Description of the local method of cable delay measurement: 1. Pulse method: Cable under test in Stop-Input of the Time-Interval-Counter. 13 BIPM GPS calibration information sheet Laboratory: AOS Date and hour of the beginning of measurements: 26.09.2003 (MJD: 52908), 20:18 UTC Date and hour of the end of measurements: 01.10.2003 (MJD: 52913), 00:12 UTC Receiver setup information Local: AOS • Maker: TTS-2 • Type: S/N 023 • Serial number: • Receiver internal delay (GPS) : 20.8 ns • Receiver internal delay (GLO) : A-001 • Antenna cable identification: Corresponding cable delay : 149.3 ns ± 0.3 ns T-014 • UTC cable identification: Corresponding cable delay : 20.4 ns ± 0.3 ns Delay to local UTC : 20.4 ns 0.5 V • Receiver trigger level: ITRF 88 • Coordinates reference frame: Latitude or X m 3738369.22 m Longitude or Y m 1148164.25 m Height or Z m 5021810.46 m Portable: BIPM K AOS TTS-2 S/N 028 0.0 (not calibrated) C123 178,78 ns ± 0,4 ns T-028 20.2 ns ± 0.3 ns 20.3 ns 0.5 V ITRF 88 3738369.26 m 1148161.57 m 5021810.81 m Antenna information Local: 3S Navigation TSA-100 0016 Portable: ITR TSA-2 GPS 3-072002 • Maker: • Type: • Serial number: If the antenna is temperature stabilised • Set temperature value : 40.5°C (105°F) 60°C Local antenna cable information • Maker: • Type: • Is it a phase stabilised cable: • Length of cable outside the building : Belden 9273, MIL-C-17G ? 5m General information • Rise time of the local UTC pulse: • Is the laboratory air conditioned: • Set temperature value and uncertainty : • Set humidity value and uncertainty : Cable identification BIPM C123 Cable delay control delay measured by BIPM 178,78 ns ± 0,4 ns 5 ns No Delay measured by local method 178.5 ns ± 0,3 ns 14 Plot of the experiment set-up: Link to the local UTC of both receivers and Antenna positions Antenna GPS Receiver BIPM TTS-2, s.n. 0028 C123 1 PPS T-028 10 MHz 2 5 MHz HP 5087A Freq. Distribution Amplifier Caesium Agilent Technologies HP5071A, opt. 001 1 PPS T-027 Datum Pulse Distribution Unit 1 10 MHz Antenna 1 PPS T-014 GPS Receiver AOS TTS-2, s.n. 0023 A-001 Description of the local method of cable delay measurement: I II 1PPS 5 MHz T-003 T-004 A B T-005 III 1PPS Stanford SR-620 Counter Ref 5 MHz T-003 T-004 T-005 T-028 A B Stanford SR-620 Counter Ref 1PPS 5 MHz T-003 T-004 T-005 A B Stanford SR-620 Counter Ref Pulse method of measurement used for antenna and 1pps cables. Test cable delay = Meas_II – (Meas_I + Meas_III)/2, Meas_I = 83.8 ns, Meas_II = 104.0 ns , Meas_III = 83.8 ns, trig. level = 0.5 V Delay(T-028) = 20.2 ns 15 BIPM GPS calibration information sheet Laboratory: KRIS Date and hour of the beginning of measurements: MJD 52934, UTC 07h Date and hour of the end of measurements: MJD 52940, UTC 00h Receiver setup information • Maker: • Type: • Serial number: • Receiver internal delay (GPS) : • Receiver internal delay (GLO) : • Antenna cable identification: Corresponding cable delay : • UTC cable identification: Corresponding cable delay : Delay to local UTC : • Receiver trigger level: • Coordinates reference frame: Latitude or X m Longitude or Y m Height or Z m Local: CSIRO NML Topcon Euro-80 L1/L2 S/N 023C10474 45.3 ns 114.8 ns Portable: BIPM K AOS TTS-2 S/N 028 0.0 (not calibrated) C123 178,78 ns ± 0,4 ns 22.4 ns 21.83 ns 0.5 V ITRF - 3120132.700 m +4085468.179 m +3763043.611 m 36°23′18.105437″ 127°22′10.277717″ 123.791 m Antenna information Local: CSIRO NML Topcon Euro-80 L1/L2 • Maker: • Type: • Serial number: If the antenna is temperature stabilised • Set temperature value : Portable: ITR TSA-2 GPS 3-072002 - Local antenna cable information • Maker: • Type: • Is it a phase stabilised cable: • Length of cable outside the building : No 4m General information • Rise time of the local UTC pulse: • Is the laboratory air conditioned: • Set temperature value and uncertainty : • Set humidity value and uncertainty : 4 ns Yes 23°C ± 1°C 50% ± 5% Cable delay control Cable identification BIPM C123 delay measured by BIPM 178,78 ns ± 0,4 ns Delay measured by local method 179,36 ns ± 0,4 ns 16 Plot of the experiment set-up: Link to the local UTC of both receivers and Antenna positions Local Antenna KRISS AOG 1 pps BIPM Antenna UTC(KRIS) 1 pps Dist. Amp. KRISS(Topcon) BIPM(TTS-2) Description of the local method of cable delay measurement: Time Interval Counter SR620 Start stop 1 pps DUT 17 BIPM GPS calibration information sheet Laboratory: CRL TOKYO JAPAN Date and hour of the beginning of measurements: 07 Nov. 2003 (MJD 52950) UTC:05hxxmxxs Date and hour of the end of measurements: 11 Nov. 2003 (MJD 52954) UTC:06h00mxxs Receiver setup information • Maker: • Type: • Serial number: • Receiver internal delay (GPS) : • Receiver internal delay (GLO) : • Antenna cable identification: Corresponding cable delay : • UTC cable identification: Local: TTR6 AOA TTR-6 451 44.8ns TTR6(219.6ns) 250.0ns GPS G Local:R100 3S Navigation R100 40T 0017 333.0ns 134.0ns R100a(204.0ns) 204.0ns Local:E-80 Javad Euro-80 8PN45EETDKW 47.2ns E80 152.15ns UTC(CRL)1pps D2 UTC(CRL)1pps C3 UTC(CRL)1pps C2 316.1ns 306.43ns 0.5V WGS-84 -3942161.90m 3368284.20m 3701886.69m 415.5ns 326.39ns 0.5V WGS-84 -3942160.08m 3368286.24m 3701887.32m 344.123ns 344.123ns 0.4V WGS-84 -3942164.215m 3368281.976m 3701887.149m 324.230ns 306.36ns 0.5 V WGS-84 -3942161.337m 3368284.951m 3701886.828m Portable: BIPM K AOS TTS-2 S/N 028 0.0ns(not calibrated) C123 178,78 ns ± 0,4 ns Corresponding cable delay : Delay to local UTC: Header Value Meas. Value • Receiver trigger level: • Coordinates reference frame: Latitude or X m Longitude or Y m Height or Z m Antenna information Local: TTR6 AOA • Maker: • Type: Down Converter • Serial number: Local:R100 3S Navigation TSA-100 0010 Local:E80 Javad RegAnt 1, S/N RA0238 Portable: ITR TSA-2 GPS 3-072002 S/N449 If the antenna is temperature stabilised Heater 105°F Cooler 75°F • Set temperature value : - Local antenna cable information Times Microwavesystems • Maker: • Type: • Is it a phase stabilised cable: • Length of cable outside the building : RG58AU No Approx. 18 m • Rise time of the local UTC pulse: • Is the laboratory air conditioned: • Set temperature value and uncertainty : • Set humidity value and uncertainty : RG214/U No Approx. 18 m LMR-400 DB No Approx. 18 m Approx. 18 m General information 4.7ns(10%-90%)pulse height 4.59v DC YES GPS RX Room 23 ±2 N/A Cable delay control Cable identification BIPM C123 delay measured by BIPM 178,78 ns ± 0,4 ns Delay measured by local method 177.46 ns : by [email protected] 177.44 ns : by [email protected] 18 Plot of the experiment set-up: Link to the local UTC of both receivers and Antenna positions ANT ANT TSA ANT TSA ANT Room 305 10MHz Ext. R100 Euro-80 Counter Ref. 40T Counter 10MHz 1PPS 1PPS 1PPS TTR6 GPS RX 5MHz HP5087A 5MHz Amp. Rec. BIPM K Out TTS-2 1PPS 10MHz 1PPS HP5087A 10MHz Amp. TRAK 6487 1PPS Amp. Oscilloquartz1 0MHz Amp. TRAK 6487 1PPS Amp. Room 302 Oscilloquartz5 MHz Amp. Pulse Dist. Amp. 10MHz Oscilloquartz Multiplier x2 Oscilloquartz 5MHz Amp. 5MHz Sigmatau AOG model 110 TRAK 6487 1PPS Amp. SR620. UTC(CRL) 1PPS Oscilloquartz5M Hz Amp. 5MHz Clock Room CS Clock 5071A 5MHz Description of the local method of cable delay measurement: TIC(1) DC +50Ω +0.4V Reference point of UTC(CRL) START SR620 DC +50Ω +2.0V STOP T1:100 Samples Mean 1PPS Sigmatau AOG model 110 TIC(2) DC +50Ω +0.5V START SR620 DC +50Ω +2.0V T2:100 Samples Mean STOP Reference We Used BIPM K TTS-2 Delay = T1 – T2 19 BIPM GPS calibration information sheet Laboratory: Date and hour of the beginning of measurements: Date and hour of the end of measurements: NIST November 26, 2003 (MJD 52969) 18:50:30 December 8, 2003 (MJD 52981) 14:38:00 Receiver setup information Local: NIST • Maker: NBS (TTR-5) • Type: NBS10 • Serial number: • Receiver internal delay (GPS) : 53.0ns • Receiver internal delay (GLO) : N/A None • Antenna cable identification: Corresponding cable delay : 199.9ns None • UTC cable identification: Corresponding cable delay : 66.7ns Delay to local UTC : 0ns 0.5V • Receiver trigger level: WGS84 • Coordinates reference frame: Latitude or X m -1288398.27 m Longitude or Y m -4721698.10 m Height or Z m +4078625.68 m Portable: BIPM K AOS TTS-2 S/N 028 0.0 (not calibrated) N/A C123 178,78 ns ± 0,4 ns None 678.9ns 0ns 0.5 V WGS84 -1288340.436 m -4721663.646 m +4078677.580 m Antenna information Local: NIST GPS NBS10 Portable: ITR TSA-2 GPS 3-072002 • Maker: • Type: • Serial number: If the antenna is temperature stabilised N/A • Set temperature value : - Local antenna cable information • Maker: • Type: • Is it a phase stabilised cable: • Length of cable outside the building : Andrew FSJ1-50A YES ~30m General information • Rise time of the local UTC pulse: • Is the laboratory air conditioned: • Set temperature value and uncertainty : • Set humidity value and uncertainty : ~1.5 ns (from 0Vdc to 0.5Vdc) YES Local: 23±1°c, Portable: 20±2°c 9% to 32% Cable delay control Cable identification BIPM C123 delay measured by BIPM 178,78 ns ± 0,4 ns Delay measured by local method 177.42ns ±0,1ns (loss = 18dB) 20 Plot of the experiment set-up: Link to the local UTC of X=-1288340.436m Y=-4721663.646m both receivers and Antenna Z=+4078677.580m positions X=-1288398.27m Y=-4721698.10m Z=+4078625.68m RF + 5Vdc +12Vdc Lab Room 4016 BIPM K 75MHz IF 50MHz LO & 15Vdc 1PPS 10MHz Distribution Amp. Distribution Amp. Clock Room 1PPS 5MHz 5MH NBS10 1PPS UTC(NIST) Description of the local method of cable delay measurement: Measure the cable’s group delay at 1575.42MHz ± 10MHz with a HP network analyzer. 21 BIPM GPS calibration information sheet Laboratory: USNO Date and hour of the beginning of measurements: 16 December 2003 (MJD 52989) 1400 UT Date and hour of the end of measurements: 23 December 2003 (MJD 52996) 1300 UT Receiver setup information • Maker: • Type: • Serial number: • Receiver internal delay (GPS): • Receiver internal delay (GLO): • Antenna cable identification: Corresponding cable delay: • UTC cable identification: Corresponding cable delay: Delay to local UTC: • Receiver trigger level: • Coordinates reference frame: Latitude or X m Longitude or Y m Height or Z m Local: MOT1 AOS SRC TTS-2 S/N 014 -47.9 N/A SPS 172.06 A10 N/A 0.0 ns 0.5 V ITRF97 +1112161.100 -4842855.428 +3985494.354 Portable: BIPM K AOS TTS-2 S/N 028 0.0 (not calibrated) C123 178,78 ns ± 0,4 ns E2 N/A -0.04 ns 0.5 V ITRF97 +1112167.181 -4842851.168 +3985493.979 Antenna information Local: 3S Navigation TSA 100 12 Portable: ITR TSA-2 GPS 3-072002 • Maker: • Type: • Serial number: If the antenna is temperature stabilised 105F • Set temperature value: Local antenna cable information • Maker: • Type: • Is it a phase stabilised cable: • Length of cable outside the building: Andrews FSJ1-50A Yes 6 meters General information • Rise time of the local UTC pulse: • Is the laboratory air conditioned: • Set temperature value and uncertainty: • Set humidity value and uncertainty: 4.1 ns Yes 25C, +/-0.5 C 20.5%, +/-4% Cable delay control Cable identification BIPM C123 Delay measured by BIPM 178,78 ns ± 0,4 ns Delay measured by local method 178.85 +/-0.01 ns 22 Plot of the experiment set-up: Link to the local UTC of both receivers and Antenna positions BIPM K Receiver 2x 10 MHz Antenna Splitter USNO TTS-2 Receiver 1PPS Distr. Amp 5MHz 2x 10 MHz Distr. Amp 1 PPS 5MHz UTC (USNO) Description of the local method of cable delay measurement: 1. 2. Set up an SRS model 620, serial 0591, time interval counter on an external 5 MHz reference. Set the counter to the "time" mode, display mean, average five events, Z=50 ohms (stop channel only), DC coupled. 3. Set up a reference 1pps signal into the "start" gate of the counter using a BNC Tee adapter. 4. Attached BNC-to-TNC adapter to the open end of the Tee, and another to the "stop" gate of the counter. 5. Lacking the proper adapters a short piece of RG-214 with type-N connectors to mate to the TNC and BNC fittings was used. 6. Two readings made of this short reference cable. One reading plugged into the TNC adapters, the other plugged into the BNC adapter after removing the TNC adapters. This allows me to estimate the adapter contribution to the cable length. 7. Reading with the TNC+RG-214 jumper was 6.706 ns, with a sigma of 2.8 ps. 8. Reading with the BNC+RG-214 jumper was 6.504 ns, with a sigma of 2.4 ps 9. The inferred contribution for the two BNC-TNC adapters is the difference, 202 ps. 10. Next, the antenna cable was substituted for the RG-214 jumper. This reading was 179.049 ns when averaged for one minute. The sigma was 6.0 ps. 11. Removing the adapter contribution gives 178.85 ns. 12. Final Answer: 178.847 ns ± 11.2 ps. 23 24 25 BIPM GPS calibration information sheet BNM – SYRTE, Observatoire de Paris Laboratory: Date and hour of the beginning of measurements: 02 February 2004 Date and hour of the end of measurements: 11 February 2004 Receiver setup information Local: NBS 51 Allen Osborne Associates • Maker: TTR-5 • Type: 051 • Serial number: • Receiver internal delay (GPS) : 54 ns • Receiver internal delay (GLO) : 505 IF • Antenna cable identification: Corresponding cable delay : 168 ns ± 0,3 ns 503 • UTC cable identification: Corresponding cable delay : Delay to local UTC : 304 ns 0.5 V • Receiver trigger level: ITRF • Coordinates reference frame: Latitude or X m 4 202 780,30 m Longitude or Y m 171 370,03 m Height or Z m 4 778 660,12 m Portable: BIPM K AOS TTS-2 S/N 028 0.0 (not calibrated) C123 178,78 ns ± 0,4 ns 497 306 ns 0.5 V ITRF 4 202 783,64 m 171 367,43 m 4 778 657,38 m Antenna information Local: A.O.A. - Portable: ITR TSA-2 GPS 3-072002 • Maker: • Type: • Serial number: If the antenna is temperature stabilised • Set temperature value : - Local antenna cable information • Maker: • Type: • Is it a phase stabilised cable: • Length of cable outside the building : / RG-58 No Approximately 6 meters General information • Rise time of the local UTC pulse: • Is the laboratory air conditioned: • Set temperature value and uncertainty : • Set humidity value and uncertainty : 4 ns Yes (21,5 ± 2) °C / Cable delay control Cable identification BIPM C123 delay measured by BIPM 178,78 ns ± 0,4 ns Delay measured by local method 178,6 ns ± 0,3 ns 26 Plot of the experiment set-up: Link to the local UTC of both receivers and Antenna positions HP 5071 A Cs clock antenna antenna 5 MHz IF TST 6490 Micro phase stepper LO 10 MHz 5 MHz NBS51 BIPMK TTS-2 HP 5087 A Freq distribution amplifier HP 5087 A Freq distribution amplifier 5 MHz 1 pps 10 MHz 1 pps 5 MHz TST 6460 Digital clock 1 pps TST 6473 Pulse distribution amplifier 1 pps Reference point UTC(OP) HP 5370B TIC Description of the local method of cable delay measurement: 10 MHz H maser 10 MHz H maser 10 MHz H maser TST 6460 Digital clock H maser 1 PPS TST 6460 Digital clock 1 PPS 1 PPS H maser TST 6460 Digital clock H maser 1 PPS 1 PPS 1 PPS B A B Tested cable A B Tested cable A START HP 5370 B STOP TIC Step 1, 3, 5 START HP 5370 B TIC STOP START Step 2 HP 5370 B TIC Step 4 The method used to calibrate the cables is a double wheight method in five steps as shown above. At each step (i) the TIC gives the result (Ri)of 100 measurments. The test cable delay is then obtained by the following formula:  R + R3   R3 + R5  R2− 1  − R4 + 2   2   Delay = + corrections 2 The corrections are the estimated delay introduced by adaptators : - 0,1 ns / adaptator STOP 27 Appendix II Measurement of portable cables at the visited laboratories Laboratory BIPM OP (before trip) PTB AOS KRIS CRL NIST USNO APL OP (after trip) BIPM C123 cable /ns 178.8 ± 0.4 179.9 ± 0.3 178.5 ± 0.2 178.5 ± 0.3 179.4 ± 0.4 177.4 177.42 ± 0.1 178.85 ± 0.01 178.6 ± 0.3 Measurement method Double Weight Pulse method Double Weight Pulse method Pulse method Pulse method Pulse method Pulse method Network Analyzer Pulse method Double Weight Pulse method 28 Appendix III Daily averages of dtk,i for each laboratory k LAB MJD k OP PTB AOS KRIS CRL NIST 52864 52865 52866 52867 52868 52869 52878 52879 52880 52881 52882 52883 52908 52909 52910 52911 52912 52913 52934 52935 52396 52937 52938 52939 52950 52951 52952 52953 52954 52969 52970 52971 52972 52973 52974 52975 52976 52977 52978 52979 52980 52981 Mean offset /ns -8.64 -9.92 -10.41 -10.15 -9.20 -8.59 -8.91 -9.68 -8.80 -10.05 -9.19 -10.63 19.24 19.24 18.88 18.80 18.74 18.74 -0.08 -0.63 -0.80 -0.70 -0.75 -0.87 -4.24 -5.76 -4.43 -4.59 -4.70 -15.20 -13.87 -13.59 -14.25 -14.80 -14.11 -14.19 -14.23 -13.77 -13.47 -14.12 -14.88 -14.57 Standard deviation of Standard Number of individual common deviation of individual common view observations the mean views /ns /ns 3.66 3.13 4.08 3.59 3.94 3.56 3.32 3.13 3.02 3.52 2.62 2.94 2.07 1.85 1.90 1.67 1.75 2.06 2.23 2.32 2.55 2.32 2.35 2.36 3.42 3.70 3.30 3.10 2.68 3.47 3.27 3.24 3.31 3.02 2.99 2.99 3.09 2.86 3.69 3.36 2.95 3.31 0.78 0.49 0.65 0.56 0.63 0.92 0.61 0.49 0.49 0.55 0.42 0.85 0.24 0.08 0.08 0.08 0.08 0.73 0.18 0.13 0.15 0.14 0.14 0.13 0.25 0.23 0.19 0.18 0.27 1.16 0.47 0.19 0.50 0.45 0.43 0.44 0.46 0.42 0.54 0.50 0.43 0.63 22 41 40 41 39 15 30 40 38 41 39 12 76 517 538 496 474 8 154 313 292 281 292 309 193 262 302 292 100 9 48 44 44 45 48 46 45 46 47 46 46 28 29 LAB MJD USNO 52989 52990 52991 52992 52993 52994 52995 52996 52996 52997 52998 52999 53000 53001 53002 53037 53038 53039 53040 53041 53042 53043 53044 53045 53046 APL OP Mean offset /ns -7.40 -6.78 -7.11 -7.17 -7.09 -7.24 -7.30 -7.13 -16.32 -16.09 -16.09 -16.03 -16.01 -16.09 -15.99 -8.99 -9.57 -9.20 -8.72 -9.03 -9.50 -9.80 -9.62 -9.97 -8.14 Standard deviation of Standard Number of individual common deviation of individual common view observations the mean views /ns /ns 2.35 2.58 2.54 2.68 2.60 2.77 2.67 2.65 0.98 0.65 0.61 0.54 0.58 0.62 0.54 3.10 2.46 2.64 2.96 2.52 2.56 2.61 3.15 2.38 4.98 0.18 0.11 0.11 0.11 0.11 0.13 0.11 0.15 0.10 0.03 0.02 0.02 0.02 0.03 0.19 0.71 0.39 0.40 0.46 0.39 0.40 0.41 0.49 0.37 1.33 178 555 527 553 557 434 556 316 99 598 594 584 580 586 8 19 39 43 42 42 42 41 41 41 14