1. Status of TL-KPGO-USNO- PTB TWSTFT Links 1 Calvin Lin, 1 Y. Huang, 1 W. Tseng, 2 M. Fujieda, and 3 Jonathan Hirschauer 1 TL, Taiwan 2 NICT, Japan 3 USNO, USA CCTF TWSTFT 23 nd WG, Sept 2015, BIPM 1

2. Outline Pacific Rim TWSTFT Network TL-KPGO-USNO-PTB TW link, 2014 TL-KPGO-USNO-PTB TW link, 2015 Summary and Conclusion – Compare with GPS TT – To be a UTC link? 2

3. East Asia ↔ KPGO: Eutelsat 172A, Ku, BW 2 M, 2.5 Mcps PRN (Sponsored by NICT ) KPGO ↔ USNO: AMC-1, Ku, BW 2.5M, 2.5 Mcps (Sponsored by USNO ) KRIS NICT KPGO PTB USNO AMC-1Eutelsat 172A TL Pacific Rim TWSTFT Network

4. EutelSat 172a, Ku, 2 Mcps AMC-1, Ku StationTL04NICT01KRIS01KPGO01USNO02 Operated byTLNICTKRISUSNO Reference HM/ UTC(TL) HM/ UTC(NICT) HM/ UTC(KRIS) HM/ Local Clock HM/ UTC(USNO) Antenna 2.4 m (Andrew) 1.8 m (Denkikogyo) 1.8 m (Denkikogyo) - 4.8m (Vertex) Transceiver Comtech KST2000A Radyne Comstream SFC1450, SFC1275A -- Norsat 4W BUC, Norsat LNB, Advantech Converter ModemSatre073Satre290Satre362Satre291Satre440 RepetitionHourly PPS REFDLY Monitoring yes - --- Facilities 4

5. PTB-TL Links, 2014 5

6. Discrepancy of AM2/EutelSat TW Link MJD 56800-56850 TL-Eutelsat-PTB vs. TL-AM2-PTB Closure around earth, NICT and TL. Slope in TL-KPGO-USNO-PTB-TL result 6

7. PTB-TL Links, 2015 7

8. PTB-NICT TW link, 2015 8

9. Summary There was discrepancy between PTB-TL AM2 TW, Eutelsat TW, and GPS TT, as more as 2~3 ns from MJD 56790~56890 (May ~ Sep 2014) After alignment slice by slice, the 2015 results of PTB-TL Eutelsat TW and GPS TT was basically coincident, except the date around MJD 57192 (TL master clock changed). ‒ TL changed transceiver from Codan to Comtech The results of PTB-NICT AM2 TW, Eutelsat TW, and GPS TT were coincident (after alignment slice by slice) 9

10. Contribute to UTC To use KPGO and USNO as relay station from east Asia to PTB: →Continuous and good quality ITU format data periodically uploaded by KPGO and other participate labs →Good maintenance including calibration of each relay stations →Setup a GPS TT station at each relay stations if possible 10