Status Report on Time and Frequency Activities at NPL India

Transcription

1 Status Report on Time and Frequency Activities at NPL India (APMP TCTF 2013) A. Sen Gupta, A. Chatterjee, A. K. Suri, A. Agarwal, S. Panja P. Arora, S. De, P. Thorat, S. Yadav, P. Kandpal, M. P. Olaniya (Taipei Nov 2013) 1

2 Major activities

3 Time Generation and Dissemination Major activities Generation and maintenance of UTC(NPLI) Time transfer using GNSS Time transfer using TWSTFT Dissemination by Telephone Time broadcast(teleclock), and NTP server. Cs Fountain Frequency Standard Frequency evaluation and international intercomparison of the first Cs Fountain. Development of the second Cs Fountain. Rubidium Clocks for Space Applications Filling up bulbs and cells with Rb. Development of physics package of the clock. Optical Frequency Standards Development of single trapped Yb + ion standard. Calibration Services Atomic Clocks (Rb& Cs Freq Standards), Time Interval Counter, Hour Meter, Teleclocks, GPS timing receivers and Stopwatch. Providing traceability to IRNSS time scale. Remote calibration setup.

4 Time generation & dissemination

5 Schematics of Generation of UTC(NPLI) 1 To Fountain Lab 5 MHz To Calibration Lab Hydrogen Maser HM1 MHM MHz 1 PPS IN 5 MHzout Distribution Amplifier1 out 5 MHz IN Micro Phase Stepper Ф resolution= 2π(2 32 )rad. Freq. Resolution = 5E19 out out 5 MHz UTC(NPLI) FREQUENCY DOUBLER 10 MHz Cs Clock AC001 Cs Clock AC001 Cs Clock AC001 Cs Clock AC001 Cs Clock AC Automatic Switching Unit START START STOP Time interval counter 1 (25psec Controller Workstation To Satellite Links

6 Schematics of Generation of UTC(NPLI) 2 To Fountain Lab 5 MHz To Calibration Lab Hydrogen Maser HM1 MHM MHz 1 PPS IN 5 MHzout Distribution Amplifier1 out 5 MHz IN Micro Phase Stepper Ф resolution= 2π(2 32 )rad. Freq. Resolution = 5E19 out out 5 MHz UTC(NPLI) FREQUENCY DOUBLER Cs Clock AC001 5MHz 10 MHz Cs Clock AC001 Cs Clock AC001 Cs Clock AC001 Cs Clock AC001 5MHz 5MHz 5MHz 5MHz 5MHz MultiChannel DMTD Phase Comparator IN Micro Phase Stepper(Aux) out out 5 MHz Controller Workstation UTC(NPLI) To Satellite Links

7 Schematics of GNSS and TWSTFT Links Saw Filter 2.5MHz Antenna Control unit 10 MHz Pik Time TTS2A SnglFreqGPS Rx Pik time TTS4 Dual FreqGPS Rx PolaRx3eTR Dual FreqGPS Rx Beacon Receiver 10 MHz Data Workstation for controlling SATRE MODEM 10 Workstation for controlling GPS Rx operation 10 MHz Distribution Amplifier2

8 Time Scale and Time Transfer Links Five Cesium clocks 1 2 UTC (NPLI) Hydrogen maser Accurate to few ns Time transfer via satellite links Antenna systems

9 Common Clock Difference for GPS Receivers

10 Typical TWSTFT Results on the EuAsia Network November 2012 November 2013 UTC(NPLI) UTC(PTB), ns MJD

11 UTC (NPLI) and UTCr(NPLI) in Last One Year UTC (NPLI) and UTCr (NPLI) UTC(NPLI) and UTCr(NPLI) From Nov2012 To Nov2013 From MJD56232 to added in UTC(NPLI) MJD UTC(NPLI) UTCr(NPLI)

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13 Cs Fountain Frequency Standards FountainI Fully operational and under evaluation FountainII Under development

14 Improved S/N ratio 1.54 Hz Earlier Now S/N ratio improvement

15 Frequency Evaluation Scheme Physics Package GHz 9.6 GHz YIG MHz 5 MHz External Reference IN Divider chain 400 MHz + + Microwave synthesizer MHz 100 MHz Divider chain DDS D1 DAQ D2 Frequency Offset [CsF(NPLI)HM] Hydrogen Maser 5 MHz 5 MHz 5MHz VCXO BVA Quartz Oscillator Phase Lock Loop

16 Frequency Stability: CsF1 vs. HM σ y (τ)= 7.1 x τ 1/2

17 Typical Uncertainty Budget Effect Bias (x ) Uncertainty (x ) 2 nd order Zeeman AC Stark (BBR) Collisions Gravity Other effects * * Total, u B to be evaluated Total u A = 1.74 x at 1day Total u B = 2.08 x 10 15

18 Frequency Evaluation A 20 day (MJD ) PFS comparison was conducted between PTB (Germany), SU (Russia), NIM (China) and NPLI (India) 2 x 1014 CSF1(PTB)CSF(NPLI) Frequency Diff ference TWSTFT GPS CP 2 56,419 56,424 56,429 56,434 56,439 MJD

19 Frequency Evaluation 4 evaluation runs for IndiaCsF1 between May 2013 October 2013 Period (MJD) Days CsFHM (x1e15) CsFUTC (x 1e15) U A (x1e15) U B (x1e15) U link (x1e15) U Total (x1e15) International intercomparison

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21 Rubidium Clock for India's Navigational Satellite System Physics Package

22 Filling Rbin Bulbs & Cells Rubidium Bulbs containing Rubidium : Mixture of Natural Rb and Rb87 Buffer gas: 2 ± 0.1 Torr Krypton gas of % purity. Rubidium Cells containing Natural Rubidium: Mixture of Rb87 ( 27.8%) and Rb85 (72.2%), Buffer gas: 9.5±0.1 Torr Nitrogen gas of % purity.

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24 369 nm 4f d6s 435 nm 3 D[3/2] 1/2 4f 14 6p 2 P 1/2 Fluorescence detection Optical frequency standard: 171 Yb + 4f 13 5d6s 1 D[3/2] 3/2 1> 1/2 0> 1/2 Imaging lens reentrant inside UHV nm 4f 14 5d 2 D 3/2 2> 3/2 1> 0> 1> 2> 1> repu ump 1 (ν IR GHz) repump 1 (ν IR ) 369 nm nm 4f 14 5d 2 D 5/2 Vacuum mbar 2> 3> 935 nm 760 nm 3/2 399 nm f 13 6s 2 4> nm 2 F7/2 760 nm nm 3> z y x 4f 14 6s 2 S 1/2 1> 0> 369 nm nm Fractional Trap assembly accuracy N. Huntemann, et. al., PRL 108, (2012).

25 Calculation of Trap Potential Trap axis Numerical calculation Harmonic Numerical fitcalculation Harmonic + Anharmonic fit 1 mm m CF35 feedthrough

26 Helical RF Resonator RF RF to input the ion trap Data Lorenzian fit Centre frequency 36.94(5) MHz FWHM MHz Quality factor 800(20)

27 Calibration Services

28 Calibration Services We are providing UTC Traceability to the Time scale of the Indian Regional Navigational Satellite System (IRNSS). This Time scale is known as the IRNWT and is maintained by the Indian Space Research Organization (ISRO). The technique used presently is all in view GPS P3. We are planning to supplement this with a dedicated TWSTFT link. We are providing Time & Frequency in house Calibration Services to Test & Calibration Labs from Govt. and Industries for the calibration of Rb & Cs Atomic Clocks, Time Interval Counters, Hour meters, Teleclocks, GPS receivers and Stop watches

29 Remote Calibration using GNSS Common View Set up at Remote Location Set up at NPL

30 Thank You for your Attention!