Report from TCTF WG on TWSTFT Coordinator: Miho Fujieda, NICT Sub Coordinator: Yi-Jiun Huang, TL Sub Coordinator: Hideo Maeno, NICT APMP TCTF meeting Nov. 26, 2012

Agenda Status on Regular TW links Asia link Asia-Hawaii-US link Asia-Eu link R&D Contribution for other fields Summary

Status on Regular TW links No.LinkSatelliteBW [MHz] Modem & Repetition ObjectiveParticipants 1AsiaGE232.5NICT, Once/hour Monitor of clocks at LF stations in Japan (JJY40/60) NICT, JJY40, JJY60, TL 2Asia- Hawaii- USNO GE232.5SATRE, Once/hour Connection with USNO NICT, TL 3Asia-EuAM22.5SATRE, Once/hour (UTC 13h~22h) Contribution for TAI NICT, NIM, NPLI, NTSC, PTB, TL, VNIIFTRI Same frequency

Status on Regular TW link: 1. Asia link *Time transfer is performed via GE23 once every hour. *Frequency band is shared with Asia-Hawaii link by time division. *Change from NICT modem to SATRE modem is planned in summer GE23 North Pacific beam JJY40 JJY60 TL ○ Circular T 10 ns 20 days

Status on Regular TW link: 2. Asia-Hawaii-USNO link *NICT and TL connect USNO via Hawaii relay station once every hour. *Instability due to the modem at Hawaii causes many outliers. Exchange of the modem may be necessary. ●, ■ Circular T NICT TL (USNO-KPGO)-(KPGO-Lab(k)) 20 days 5 ns GE23 North Pacific beam

Status on Regular TW link: 3. Asia-Eu link AM2 Ku beam Results with PTB day *Time transfers are performed via AM2 once every hour from 13h to 22h UTC among NICT, NIM, NPLI, NTSC, PTB, TL and VNIIFTRI. *Time links between PTB and NICT, TL, NTSC, NPLI are adopted as TAI link.

Status on Regular TW link: 3. Asia-Eu link *According to the satellite company, AM2 satellite at 80 E will stop the service in the end of June *Asia-Eu link will be continued via AM2 until the time. *It is not decided yet which satellite will be used for the link after that. Candidate 1: Eutelsat 70B at 70E Candidate 2: AM4 at 80E *Launch: Dec 2012, Service start: Feb 2013 *2 transponder for Eu-Asia connection * 20,000 USD/month for 2.5Mbps 12,000 USD/month for 1.0Mbps Link fee is too expensive for almost labs? Decrease of chip rate may be necessary for cost reduction. *Launch: 2014 *1 transponder for Eu-Asia connection

R&D 200 kHz 31.2 MHz f σ: 12 ps DPN: Dual Psuedo Random Noises *DPN measurement has been performed between NICT, Japanese domestic station and TL. Carrier phase TWSTFT *NICT develops carrier phase TW technique. *TL also starts the development. *Experiment in NICT-TL link will be tried near future. TWSTFT CP: 4x10 1 s H-maser comparison in 150-km baseline M. Fujieda et al., accepted by IEEE TUFFC.

Contribution for other field Neutrino’s TOF measurement demands calibrated time transfer! Calibration accuracy less than 1 ns by TWSTFT is very attractive. J-PARC Super KAMIOKANDE Neutrino beam Image of T2K (Tokai to Kamioka) experiment Target accuracy of TOF measurement is 10 ns in T2K. To realize that, *T2K group just installed Septentrio GPS receivers and Rb clocks in the both ends for ns-level time synchronization. *NICT provided a precise timing measurement system. GPS link calibration by TWSTFT mobile station will be performed next year. TOF: Time of flight

Summary Regular TWSTFT measurements are stably performed. Especially Asia-Eu link contributes for TAI calculation. Unfortunately exchange of the satellite is necessary next year. One of the candidates, Eutelsat 70B, will cover Australia, France, etc. The policy for next year should be decided soon. R&D has been actively done at NICT and TL. Carrier phase TWSTFT reaches a H-maser limit in seconds. Accurate and precise time transfer in ns-level is demanded by high energy physics experiment.

Thank you for your kind attention.