Message-ID: <8B3E03343914D411A51000062938C79601539DA2@golf.npl.co.uk> From: Jon Clarke To: "IGS_IGSMail (E-mail)" , "EUREF_Mail (E-mail)" , "Lewandowski (E-mail)" , "Petit_Gerard (E-mail)" , "Moussay_Philippe (E-mail)" , "Schmidt_Lara (E-mail)" , "Bauch_Andreas (E-mail)" , "Nelson_Lisa (E-mail)" , "Matsakis_Demetrios (E-mail)" Cc: Peter Whibberley , Setnam Shemar , John Davis , John Laverty Subject: [IGSMAIL-3412]: NPL time transfer disruption (NPLD, NPLF, AA276, TFS101, TFS102, BIPM F) Date: Wed, 11 Jul 2001 11:44:39 +0100 Sender: owner-igsmail Precedence: bulk ****************************************************************************** IGS Electronic Mail 11 Jul 03:44:55 PDT 2001 Message Number 3412 ****************************************************************************** Author: Jon Clarke, NPL Subject: NPL time transfer disruption Dear Colleagues, There has been about 72 hours of disruption to NPL's GPS and GLONASS time transfer receivers but they are now functioning again. My apologies for this significant interruption in our data. We are changing our configurations so that we have better protection in the future. Regards, Jon Contents: Problems K-band two-way X-band two-way NPLD, Ashtech Z12T NPLF, Javad Legacy AA276, AOA TTR5A TFS101 and TFS102, Motorola Oncores BIPM F, 3S Navigation R100 Problems There was a power cut during 7 and 8 July which was not handled properly for Building 2, which holds most of our time transfer equipment. In Building 5 a distribution amplifier failed and signals were moved to a new one, giving a step in the signal chain that forms UTC(NPL) for the equipment in Building 5, although Building 2 was unaffected. We are correcting our time interval measurements and time transfer equipment (where necessary) so that no change is visible to the outside world. K-band two-way Was entirely unaffected by the disruption. The measurements immediately before and after the weekend were complete and correct. X-band two-way Did not gather data over the weekend, but was otherwise unaffected. NPLD, Ashtech Z12T Has been using a different antenna whilst it was in a common-antenna configuration with the BIPM's calibrated Ashtech Z12T, BIPMC. As a result I have not transmitted its data since 1 July. It gathered no data over the weekend. It was restored yesterday (11 July) and its data is being transmitted again. NPLF, Javad Legacy As I cannot yet register this GPS/GLONASS receiver with the IGS, I have stopped tranmsitting its data whilst I use it to characterise some new monuments. It gathered no data over the weekend. AA276, AOA TTR5A Our reference single-channel GPS CV receiver is sourced differently to all the other receivers so it was affected by the step in the timescale. I will start publishing its data again today or tomorrow. TFS101 and TFS102, Motorola Oncores These multi-channel CV receivers gathered no data for the weekend. They have been restored and their data is being transmitted again. BIPM F, 3S Navigation R100 This gathered no data for the weekend. It has been restored and its data is being transmitted again. ------------------------------------------------------------------------ - Mr Jon Clarke Time and Frequency Section, tel: +44 (0) 20 8943 6548 Centre for Electromagnetic and Time Metrology, fax: +44 (0) 20 8943 6529 National Physical Laboratory, e-mail: jon.clarke@npl.co.uk Queens Road, Teddington, web: http://www.npl.co.uk/npl/ctm/ TW11 0LW, U.K. ------------------------------------------------------------------------ -