Re: [LEAPSECS] Problems with GLONASS Raw Receiver Data at Start of New Year

From: Richard Langley <lang_at_UNB.CA>
Date: Sat, 14 Jan 2006 11:59:06 -0400 (AST)

The problem existed for only 2-1/2 minutes, not hours. Might be
coincidental with the leap second but I've not noticed this problem
at other times. Stations were not running during the previous leap second.
UNB1 Web page is here: <>.
IGS Central Bureau Web page is here: <>
-- Richard Langley

On Sat, 14 Jan 2006, Rob Seaman wrote:

>On Jan 13, 2006, at 7:51 AM, Richard Langley wrote:
>> The International GNSS Service (IGS) includes a sub-network of
>> continuously
>> operating GLONASS monitor stations (about 50) including one at the
>> University
>> of New Brunswick (UNB1). At UNB1 we lost C1 (coarse code on L1
>> frequencies),
>> P1 (precision code on L1), and P2 (precision code on L2)
>> observations on the 5
>> GLONASS satellites we were tracking at 00:01:30 GPS Time on 1
>> January 2006
>> along with phase jumps in L1 (carrier phase on L1) and L2 (carrier
>> phase on
>> L2).
>Perhaps you can expand on the meaning of all this. Presumably this
>would represent an infrequent occurrence? What are the implications
>for downstream systems? For that matter, what systems lie downstream?
>> Code measurements were back at 00:04:00.
>So the problem extended for 2.5 hours from 00:01:30 - 00:04:00 GPS
>Time? Were there repercussions that have persisted after this?
>> I have just learned from one of the IGS analysis centres that all
>> January 1
>> IGS GLONASS observation files that they checked show a similar
>> problem.
>The leap second has not been mentioned, but presumably we are to
>infer that it triggered this behavior? Would be absolutely delighted
>to learn more about the IGS, both in general and to provide context
>for interpreting this report.
>As with the previous mail, I won't claim to be able to attach an
>estimation of the importance of the events described. We obviously
>all believe leap seconds are worthy of discussion or we wouldn't be
>here. I presume many of us read RISKS Digest and can dream up scary
>scenarios. But there are also risks associated with *not* having
>leap seconds, with allowing DUT1 to increase beyond 0.9s, for
>instance. And events triggered by those risks would not draw
>worldwide scrutiny - they could occur year-round and the media circus
>would have moved on.
>Rob Seaman

 Richard B. Langley E-mail:
 Geodetic Research Laboratory Web:
 Dept. of Geodesy and Geomatics Engineering Phone: +1 506 453-5142
 University of New Brunswick Fax: +1 506 453-4943
 Fredericton, N.B., Canada E3B 5A3
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Received on Sat Jan 14 2006 - 07:59:28 PST

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