Meeting of TWSTFT WG SP Boras Sweden 2
Meeting of TWSTFT WG. SP, Boras (Sweden) 2 -3 October 2008 INRIM TWSTFT station report F. Cordara L. Lorini I. Sesia Istituto Nazionale di ricerca metrologica - INRIM
Meeting of TWSTFT WG. SP, Boras (Sweden) 2 -3 October 2008 Summary • Station present status • Satellite change • Performance of new links • Calibration with TUG 03 portable station Istituto Nazionale di ricerca metrologica - INRIM
Meeting of TWSTFT WG. SP, Boras (Sweden) 2 -3 October 2008 Present configuration of IT 02 TWSTFT station at INRIM Modem: Timetech SATRE s/n 079 Modem Current software version 4. 15. 1 Time Tag Shift: DT=+0. 5 s Transceiver: Anacom Anasat Se. KU 4 W Antenna: Prodelin model 1184 (1. 8 m) INRIM lab Acquisition system (MUX+TIC) UTC(IT) 1 PPS Generator TTL Driver 1 PPSTX rear front SATRE 079 1 PPS IN 10 MHz IN H maser Modem reference: Link to UTC(IT): H-Maser Symmetricom (BIPM code 1401102) REFDELAY (UTC(IT)-1 PPSTX) measurement @ min 04 for ALL labs Istituto Nazionale di ricerca metrologica - INRIM
Meeting of TWSTFT WG. SP, Boras (Sweden) 2 -3 October 2008 Installation of 4 -port feed and waveguide switches • IS-3 R requires different polarization configurations for EU-EU and EU-USA links • EU-EU. TXPol: V, RXPol: H • EU-USA. TXPol: H, RXPol: V • Polarization used by a 4 -port feed and two waveguide switches • Hardware and installation provided by Intelsat • Sporadic failures of switching detected during September. Causes under investigation Istituto Nazionale di ricerca metrologica - INRIM
Meeting of TWSTFT WG. SP, Boras (Sweden) 2 -3 October 2008 Common clock measurements • Installation of 4 -port feed and switches can cause a change of non-reciprocal station delay • Common clock measurements IT 01 -IT 02 provided evaluation of IT 02 delay change after the 4 -port feed installation (MJD 54480). IT 01 plays the role of reference station • Jump was estimated averaging data before and after 4 -port feed installation • Jump(IT 02) = -[IT 01 -IT 02(2 p)]+[IT 01 -IT 02(4 p)] = (+1. 4 ± 0. 2) ns • DESDVAR(IT 02) = -2[Jump(IT 02)] = (-2. 8 ± 0. 4) ns Istituto Nazionale di ricerca metrologica - INRIM
Meeting of TWSTFT WG. SP, Boras (Sweden) 2 -3 October 2008 Satellite change • Satellite change from IS 707 to IS 3 R on MJD 54502 • Last sessions on IS 707 at 8 UTC. 1 -2 sessions on average lost due the antenna repointing • IT-PTB re-calibration change due to the satellite switch • Main stations (IT 02 for INRIM) switched satellite at 10 UTC MJD 54502 • PTB changed its main station (PTB 01 to PTB 04) at the same time of the satellite switch • INRIM and PTB operated two stations at the same time (IT 01 and IT 02 for INRIM, PTB 01 and PTB 04 for PTB) to provide a reference link. • IT-PTB CALR change was determined with 2 independent methods • Bridging main link TW data with respect to the reference TW link given by the secondary stations. • Bridging with respect to a reference GPS link (PPP solution, BIPM) Istituto Nazionale di ricerca metrologica - INRIM
Meeting of TWSTFT WG. SP, Boras (Sweden) 2 -3 October 2008 TW data bridge at the satellite change • Main link • IT 02 -PTB 01 on IS 707 (until MJD 54502) • IT 02 -PTB 04 on IS 3 R (after MJD 54502) • Reference link • IT 01 -PTB 04 on IS 3 R (from MJD 54496 to MJD 54511) • PTB calculated the time jump at the satellite change • Jump: (IS 3 R, PTB 04) – (I 707, PTB 01) calculated via the reference link • Jump = (352. 3 ± 1. 1) ns Istituto Nazionale di ricerca metrologica - INRIM
Meeting of TWSTFT WG. SP, Boras (Sweden) 2 -3 October 2008 • Diurnal oscillation during the top of the summer (July 2007 and June 2008) seems to be reduced switching from IS 707 to IS 3 R • Pk-to-pk almost reduced of 30 -50% for IT-NIST link • Correlation with transceiver internal temperature still present (same phase for 2007 and 2008) indicating a possible temperature dependence of Anacom Anasat transceiver Istituto Nazionale di ricerca metrologica - INRIM
Meeting of TWSTFT WG. SP, Boras (Sweden) 2 -3 October 2008 Analysis of stability – 2007/2008 UTC(NIST)-HM(IT) data, quadratic fit residuals Summer 2007 -IS 707 Summer 2008 -IS 3 R Istituto Nazionale di ricerca metrologica - INRIM
Meeting of TWSTFT WG. SP, Boras (Sweden) 2 -3 October 2008 Calibration trip of the TUG 03 travelling station • Calibration trip including PTB, OP, NPL, INRIM (Fidelity contract). VSL, METAS • Calibration at INRIM on 15 -16 September. Both IT 01 and IT 02 independently calibrated • More than 150 sessions IT 02 -TUG 03 • About 14 sessions IT 01 -TUG 03 Istituto Nazionale di ricerca metrologica - INRIM
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