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
Major activities
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.
Time generation & dissemination
Schematics of Generation of UTC(NPLI) 1 To Fountain Lab 5 MHz To Calibration Lab Hydrogen Maser HM1 MHM2010 5 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 2 5071AC001 Cs Clock 3 5071AC001 Cs Clock 6 5071AC001 Cs Clock 7 5071AC001 Cs Clock 8 5071AC001 1 4 2 3 6 7 5 Automatic Switching Unit START START STOP Time interval counter 1 (25psec resolution) @ Controller Workstation To Satellite Links
Schematics of Generation of UTC(NPLI) 2 To Fountain Lab 5 MHz To Calibration Lab Hydrogen Maser HM1 MHM2010 5 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 2 5071AC001 5MHz 5MHz @ 10 MHz Cs Clock 3 5071AC001 Cs Clock 6 5071AC001 Cs Clock 7 5071AC001 Cs Clock 8 5071AC001 5MHz 5MHz 5MHz 5MHz 5MHz MultiChannel DMTD Phase Comparator IN Micro Phase Stepper(Aux) out out 5 MHz Controller Workstation UTC(NPLI) Aux @ To Satellite Links
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 operation @ 10 MHz @ Workstation for controlling GPS Rx operation 10 MHz Distribution Amplifier2
Time Scale and Time Transfer Links Five Cesium clocks 1 2 UTC (NPLI) 3 4 5 Hydrogen maser Accurate to few ns Time transfer via satellite links Antenna systems
Common Clock Difference for GPS Receivers
Typical TWSTFT Results on the EuAsia Network November 2012 November 2013 UTC(NPLI) UTC(PTB), ns MJD
UTC (NPLI) and UTCr(NPLI) in Last One Year UTC (NPLI) and UTCr (NPLI) 20 15 10 5 0 5 10 UTC(NPLI) and UTCr(NPLI) From Nov2012 To Nov2013 From MJD56232 to 56349 added 190.0 in UTC(NPLI) 56200 56250 56300 56350 56400 56450 56500 56550 56600 56650 MJD UTC(NPLI) UTCr(NPLI)
Cs Fountain Frequency Standards FountainI Fully operational and under evaluation FountainII Under development
Improved S/N ratio 1.54 Hz Earlier Now S/N ratio improvement
Frequency Evaluation Scheme Physics Package 9.192631770 GHz 9.6 GHz YIG + 407.368230 MHz 5 MHz External Reference IN Divider chain 400 MHz + + Microwave synthesizer 7.368230 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
Frequency Stability: CsF1 vs. HM σ y (τ)= 7.1 x 10 13 τ 1/2
Typical Uncertainty Budget Effect Bias (x 10 15 ) Uncertainty (x 10 15 ) 2 nd order Zeeman 50.52 0.06 AC Stark (BBR) 16.92 0.23 Collisions 10.3 2.06 Gravity 19.6 0.11 Other effects * * Total, u B 42.3 2.08 to be evaluated Total u A = 1.74 x 10 15 at 1day Total u B = 2.08 x 10 15
Frequency Evaluation A 20 day (MJD 5641956439) PFS comparison was conducted between PTB (Germany), SU (Russia), NIM (China) and NPLI (India) 2 x 1014 CSF1(PTB)CSF(NPLI) Frequency Diff ference 1 0 1 TWSTFT GPS CP 2 56,419 56,424 56,429 56,434 56,439 MJD
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) 5641956439 20 51.10 0.04 0.50 2.43 0.17 2.49 5651456529 15 17.33 1.41 0.44 2.08 0.23 2.14 5655456564 10 155.40 2.16 0.74 2.37 0.35 2.51 5658956599 10 632.92 2.76 0.33 2.42 0.46 2.48 International intercomparison
Rubidium Clock for India's Navigational Satellite System Physics Package
Filling Rbin Bulbs & Cells Rubidium Bulbs containing Rubidium : Mixture of Natural Rb and Rb87 Buffer gas: 2 ± 0.1 Torr Krypton gas of 99.999% 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 99.995% purity.
369 nm 4f + 13 5d6s 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 369.5 nm 4f 14 5d 2 D 3/2 2> 3/2 1> 0> 1> 2> 1> repu ump 1 (ν IR +3.07 GHz) repump 1 (ν IR ) 369 nm + 435 nm 4f 14 5d 2 D 5/2 Vacuum 10 12 mbar 2> 3> 935 nm 760 nm 3/2 399 nm + 369 24f 13 6s 2 4> nm 2 F7/2 760 nm + 935 nm 3> z y x 4f 14 6s 2 S 1/2 1> 0> 369 nm + 435 nm Fractional Trap assembly accuracy 7.1 10 17 N. Huntemann, et. al., PRL 108, 090801 (2012).
Calculation of Trap Potential Trap axis Numerical calculation Harmonic Numerical fitcalculation Harmonic + Anharmonic fit 1 mm m CF35 feedthrough
Helical RF Resonator RF RF to input the ion trap Data Lorenzian fit Centre frequency 36.94(5) MHz FWHM 0.046 MHz Quality factor 800(20)
Calibration Services
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
Remote Calibration using GNSS Common View Set up at Remote Location Set up at NPL
Thank You for your Attention!