From john.davis@npl.co.uk Thu Feb 26 11:52 EST 1998
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To: Jim Ray
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From: John Davis
Subject: IGS/BIPM GPS TIME TRANSFER
Date: Thu, 26 Feb 98 16:53:44 GMT
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IGS/BIPM PILOT PROJECT TO STUDY ACCURATE TIME AND FREQUENCY
COMPARISONS USING GPS PHASE AND CODE MEASUREMENTS
SUMMARY
Agency or group: Centre for Time Metrology, National Physical
Laboratory, Queens Road, Teddington, Middlesex, TW11 OLW.
Contact persons:
Jon D Clarke (new staff, fax +44-181-943-7138, phone and e-mail to
follow)
John A Davis, phone +44-181-943-7137, fax +44-181-943-7138, e-mail
john.davis@npl.co.uk.
Areas of participation:
1) Deployment of GPS receivers : Yes
2) GPS data analysis: No
3) Analysis of instrumentation delays: Yes
4) Time transfer comparisons: Yes
Dear Jim Ray,
Thank you very much for your invitation to take part in the above IGS
/ BIPM pilot project on accurate GPS time and frequency transfer. The
National Physical Laboratory (NPL) will be very pleased to
participate in the study. I have briefly outlined NPL's capabilities
in each area of the proposed study below:
1) Deployment of GPS receivers
NPL owns two geodesic quality timing GPS receivers, an Ashtech Z12-T
receiver and an Allen Osborne Associates TTR-4P receiver. We are at
present forwarding data from the Ashtech Z12-T receiver to the
University of Bern for analysis. NPL's time scale is based on two
Sigma Tau model MHM 2010 Active Hydrogen Masers. Our station is not
yet registered with the IGS central bureau, we will do this as soon
as possible.
2) GPS Data analysis
NPL does not have the resources to actively participate in the GPS
data analysis aspects of the project at present. However we would
like to be kept informed of progress in this area, and to
seek to participate at a later date.
3) Analysis of instrumentation delays.
NPL hope to actively participate in this part of the study. We intend
to perform "zero baseline" common-clock measurements between our two
receivers to determine their delay stability.
4) Time transfer comparisons
NPL owns three NIST type common-view GPS receivers which are used to
follow the BIPM common-view time transfer schedule. In addition NPL
routinely operates a Two-Way Satellite Time and Frequency Transfer
(TWSTFT) earth station. We regularly perform TWSTFT time transfers
with seven other laboratories in Europe and North America, including
USNO. We are also setting up a 3S Navigation R100-40 GLONASS
receiver. We hope to forward GLONASS data to BIPM soon.
I would be very pleased if you would acknowledge our request to
participate in the study, and advise us of any actions that we need
to take in the immediate future.
Best Regards
John A Davis.
From jon.clarke@npl.co.uk Fri Mar 20 08:32 EST 1998
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To: Thomas_Claudine
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From: Jon Clarke
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Subject: IGS meeting/records
Date: Fri, 20 Mar 1998 12:45:39 +0000
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Dear Claudine Thomas,
I am working on geodesic GPS time transfer and I am listed as a member
of the new IGS BIPM working group.
Unfortunately I was not able to forward my fax number and e-mail
address as they were not previously available. They are listed at the
end of this message. I would be very pleased if you would update your
records.
I would like to attend the IGS meeting proposed for 22 and 23 June, but
unfortunately I am unavailable for the week 20 to 28 June.
Yours sincerely,
Jon Clarke
Mr Jon Clarke,
e-mail jon.clarke@npl.co.uk,
tel 0044 181 943 6548,
fax 0044 181 943 7138,
National Physical Laboratory,
Queens Road,
Teddington,
TW11 0LW,
U.K.
From Setnam.Shemar@npl.co.uk Tue Aug 28 09:13:34 EDT 2001
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From: Setnam Shemar
To: "'jimr@maia.usno.navy.mil'"
Cc: Jon Clarke
Subject: Registration for IGS/BIPM Pilot Project email exploder
Date: Tue, 28 Aug 2001 14:12:37 +0100
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Status: RO
Dear Jim Ray,
Let me introduce myself. I have been working on TWSTT in the last three
or so years at the National Physical Laboratory (NPL) in the UK.
As you will already know, Jon Clarke will be leaving NPL on September
14th and I will take over operations of NPL's GPS carrier phase
receivers (NPLD and the recently acquired Javad) from him. Consequently,
I would like to subscribe to your IGS/BIPM Pilot Project email exploder.
Please could you put me on the distribution list ? My details are given
below.
Yours sincerely,
Setnam Shemar
Dr Setnam Shemar
Centre for Electromagnetic and Time Metrology
National Physical Laboratory
Queens Road
Teddington
Middlesex
TW11 0LW
UK
Tel: +44 20 8943 7118/6351
Fax: +44 20 8943 6529
Email: setnam.shemar@npl.co.uk