Subject: [IGEXMail-0583] NPL Igex station restarts
From: Jon Clarke <[email-masked]>
Date: 13 Dec 1999 20:11:35

Reply-To: IGEX Mail <[email-masked]>
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IGEXMail                13-Dec-1999 20:11:35                   Message No 0583
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Author: Jon Clarke <[email-masked]> 
Subject: NPL Igex station restarts 

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Dear Colleagues,=20

I am happy to announce that NPL is once again gathering data from our 3S =
Navigation R100-40T receiver, NPLC.=20

This follows a disappointingly long period since July 27 of this year in =
which either the R100 receiver or myself were not available. There is =
some data during this 127 day gap, but not much - I shall process and =
contribute any worthwhile lengths.=20

Tonight I shall tentatively FTP the data for MJDs 51513 - 51517 to BKG =
to restart our contribution to IGEX (TEQC.exe did not report any severe =
problems with this data).=20

Our contributions should then continue as "normal" if there are no =
problems, and the receiver continues working. Also, the CCTF-format =
common view data from NPLC is now being posted to the NPL ftp site again =
(please see attached text files).=20

Note on R100 phase resets
-------------------------
Other users may not be aware that the R100 appears to reset all its =
carrier phase measurements to 50000000 cycles upon receipt of the =
"HEADER" command (which must be sent if the raw data is gathered via the =
serial port and then processed into Rinex). This has been confirmed by =
several other R100 users, and it caused all NPLC measurements taken =
before July 27 to have hourly resets to that value. This should now only =
occur at midnight, as I now only collect data into daily files.=20

Note on incorrect ordering of R100 measurements
-----------------------------------------------
Also, I have been informed by BKG that some NPLC Rinex files have some =
measurements in the wrong order, and again this has been experienced by =
at least two other R100 users - please be aware of this if you use our =
data.=20

My apologies for the severe delay in restarting our contributions.=20

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 7138        Queens Road, Teddington, TW11 0LW, U.K.
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