Subject: [IGSMAIL-2965]: NPL GPS time monitoring service
From: Jon Clarke <[email-masked]>
To: RIN_SNG_mail_list <[email-masked]>, IGS_IGSMail <[email-masked]>
Cc: CETM_time_technical <[email-masked]>
Date: Wed, 2 Aug 2000 10:34:54 +0100

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IGS Electronic Mail      02 Aug 09:42:39 PDT 2000      Message Number 2965
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Author: Jon Clarke
Subject: NPL GPS time monitoring service

Dear Colleagues,

The National Physical Laboratory has started monitoring the timing of 
the GPS constellation, and publishing the results. These are available 
at:

http://www.npl.co.uk/npl/ctm/gps_bulletin.html .

This is primarily to aid UK stand-alone users of GPS time in obtaining 
traceability from their receiver to the UK national time standard, 
UTC(NPL), and to provide independent integrity monitoring of GPS time.

This service is still under development, and is expected to expand over 
the coming months. Currently NPL reports a single daily mean value for 
UTC(NPL) - GPS time via multi-channel single-frequency C/A code 
measurements, and reports any anomalous satellite measurements.

Thanks go to our colleagues at USNO who have provided useful 
information.

I would welcome any comments on this service.

Regards,
Jon Clarke

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Mr Jon Clarke                                Time and Frequency Section,
[email-masked]      Centre for Electromagnetic and Time Metrology,
tel: +44 (0) 20 8943 6548                  National Physical Laboratory,
fax: +44 (0) 20 8943 6529        Queens Road, Teddington, TW11 0LW, U.K.
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