1. Yasuhisa Fujii National Metrology Institute of Japan (NMIJ) Jia-Lun Wang National Time and Freq. Standards Lab,Taiwan (TL) Michael Wouters and Bruce Warrington National Measurement Institute, Australia (NMIA) WG on GNSS Report 2012 APMP Technical Committee on Time and Frequency Wellington, New Zealand 26 November 2012

2. Objectives Mission To support time and frequency applications of Global Navigation Satellite Systems (GNSS) in APMP Working Group on GNSS  Coordinate GNSS time and frequency comparisons within APMP  Develop support for new GNSS techniques and applications  Support research into GNSS time and frequency transfer Coordinator: Michael Wouters (NMIA) Sub-coordinators: Jia-Lun Wang (TL) and Yasuhisa Fujii (NMIJ)

3. 1.1 GNSS receiver comparisons Circulate the TL dual frequency receiver Circulate the NMIJ single frequency receiver More frequent comparisons Work program Outcome Extend the dual frequency comparison to L1/L2 delays Support for P3 and PPP time links Develop formal protocols for the comparisons Formal recognition Reduction of u B

4. 1.2 GNSS receiver comparisons Circulate the TL dual frequency receiver Circulate the NMIJ single frequency receiver Extend the dual frequency comparison to L1/L2 delays Develop formal protocols for the comparisons Work programProgress The dual-frequency system completed three main rounds throughout the region and a side visit to NMISA in South Africa. Final reporting of results has been delayed by the decision to do this according to a recognized protocol. Further comparison rounds have also been delayed until a protocol has been adopted and recognized.

5. 1.3 GNSS receiver comparisons Circulate the TL dual frequency receiver Circulate the NMIJ single frequency receiver Extend the dual frequency comparison to L1/L2 delays Develop formal protocols for the comparisons Work programProgress More than half of the TAI links within APMP are now based on PPP with geodetic receivers. Currently calculate and report the L1 C/A code delay only. Delay values are also available in principle for both P/L1 and P/L2, to support P3 (code) time transfer for geodetic dual-frequency receivers

6. 1.4 GNSS receiver comparisons Circulate the TL dual frequency receiver Circulate the NMIJ single frequency receiver Extend the dual frequency comparison to L1/L2 delays Develop formal protocols for the comparisons Work programProgress APMP TCTF and WG GNSS previously identified the importance of a formal protocol, to ensure recognition of results (for example, to support reduction of u B for laboratories contributing to TAI). A working group was formed to prepare a draft protocol, including representatives from BIPM, PTB (Andreas Bauch) and NMIA (Bruce Warrington). To make progress, the technical details have been separated from the full protocol. The draft technical protocol will be introduced in the GPS receiver calibration tutorial tomorrow. Volunteers to help with preparation of the protocol will be welcomed !

7. Food for thought LabReceiverLast caluB (ns)Link SFDFPPP NMIJavad Euro-160,Septentrio PolaRx3Oct 20105.2GPSPPP NICTSeptentrio PolaRx2, PolaRx2e?Jun 20094.6TWGPPP NIMJavad Euro-160, Septentrio,GTR-50Dec 20095.2GPS P3 SGTTS-3, Septentrio?Mar 20105.3GPSPPP NPLITTS-2,Septentrio??Jun 20127.2GPSPPP TLZ12T,Ashtec?Dec 20115.0TWGPPP KRISSZ12T, AshtecAug 20055.0GPSPPP NMISASeptentrio PolaRx3TRAug 200419.9GPS P3 VMITopcon Euro-80,Septentrio PolarX3TRAug 200420.1GPS P3 MSLTopcon Euro-80Aug 200420GPS P3 NIMTTopcon, OncoreAug 200420GPS P3 NMIJZ12T,AshtecAug 20045.2GPSPPP KIM-LIPITTS-3,OncoreSep 200620.1GPS MC Dec 2011 GPS calibration questionnaire Circular T October 2012 Desired cals

8. 2. Support for new GNSS techniques and applications GNSS time and frequency transfer for remote calibration  Survey remote calibration activities within the APMP  Provide an opportunity to discuss related issues such as the estimation of uncertainty, the use of GNSS-disciplined oscillators, and accreditation of calibration services  Report back to the APMP TCTF, summarising information which may be useful to economies operating or developing remote calibration facilities  Consider guidelines for harmonization/standardisation of remote calibration services, and for the assessment of these services for CMCs under the CIPM MRA The WG is especially grateful for the leadership of Michito Imae of NMIJ in this work

9. 3. Support research into GNSS time and frequency transfer At the recent CCTF meeting, the outgoing chair of the Working Group on GNSS Time Transfer Standards, Dr Judah Levine (NIST), recommended: “... the ongoing development of standardised time-transfer hardware, open sharing of receiver firmware and processing software, and greater automation of laboratory comparisons”.

10. Tutorial session  Report on BIPM calibration visit (NIM)  Report on BIPM calibration visit (NMIA)  Lab demonstration (TL)  Calibration data analysis Introduction to the draft technical protocol Sample analysis A few case studies - noisy data etc Take away exercise Resources  Future plans for the WG on GNSS  Q&A Calibration of time-transfer receivers Thanks to Huang-Tien Lin (TL) for organizing this session

11. National Measurement Institute Bradfield Road West Lindfield NSW 2070 Australia Phone:+61 2 8467 3501 Email:michael.wouters@measurement.gov.aumichael.wouters@measurement.gov.au Web:www.measurement.gov.au/timewww.measurement.gov.au/time