[IGSSTATION-805]: 1 Sec Epoch Error for GOPE and THU2 (fwd)

[Richard Langley]

Another GLONASS receiver problem report.
-- Richard Langley

===
 Richard B. LangleyE-mail: [EMAIL PROTECTED]
 Geodetic Research Laboratory  Web: http://www.unb.ca/GGE/
 Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142
 University of New Brunswick   Fax:  +1 506 453-4943
 Fredericton, N.B., Canada  E3B 5A3
 Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/
===

-- Forwarded message --
Date: Fri, 3 Feb 2006 14:29:20 +0100
From: "Habrich, Heinz" <[EMAIL PROTECTED]>
To: "IGSSTATION_Mail (E-Mail)" <[EMAIL PROTECTED]>
Cc: [EMAIL PROTECTED], [EMAIL PROTECTED],
 "Jakub Kostelecky (E-Mail)" <[EMAIL PROTECTED]>
Subject: [IGSSTATION-805]: 1 Sec Epoch Error for GOPE and THU2

**
IGS Station Mail  03 Feb 05:29:32 PST 2006  Message Number 805
**

Author: Heinz Habrich, Peter Neumaier

The GLONASS observations from the sites GOPE and THU2 show
obviously wrong observation epochs in the RINEX files since
January 1, 2006. This inconsistency is caused by the leap second
for UTC as was introduced at that day. We assume that the two mentioned
stations don't handle the new leap second correctly and ask the
station operators the check the receiver settings.

A code single point positioning results in an error
of about 300 m, as we found in our analysis. The RINEX header show
13 sec for GPS-UTC difference, but now it should be 14 sec.

Furthermore, we detected the wrong 13 sec for GPS-UTC in the RINEX header for
DARR and STR2, but these 2 stations could be analyzed without
problems.

Re: the tail wags the dog

[Richard Langley]

On Mon, 23 Jan 2006, Clive D.W. Feather wrote:

>Steve Allen said:
>> The official time of the US for commerce and legal purposes is UTC(NIST).
>> The official time of the US DOD is UTC(USNO).
>> The official time of the Federal Republic of Germany is UTC(PTB).
>> etc.
>
>The official time of the UK is GMT.

where GMT = UTC(NPL), not GMT = UT1, right?

-- Richard Langley


>
>--
>Clive D.W. Feather  | Work:  <[EMAIL PROTECTED]>   | Tel:+44 20 8495 6138
>Internet Expert | Home:  <[EMAIL PROTECTED]>  | Fax:+44 870 051 9937
>Demon Internet  | WWW: http://www.davros.org | Mobile: +44 7973 377646
>Thus plc||
>


===
 Richard B. LangleyE-mail: [EMAIL PROTECTED]
 Geodetic Research Laboratory  Web: http://www.unb.ca/GGE/
 Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142
 University of New Brunswick   Fax:  +1 506 453-4943
 Fredericton, N.B., Canada  E3B 5A3
 Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/
===

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

[Richard Langley]

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: <http://gge.unb.ca/Resources/UNB1.html>.
IGS Central Bureau Web page is here: <http://igscb.jpl.nasa.gov/>
-- 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
>NOAO
>


===
 Richard B. LangleyE-mail: [EMAIL PROTECTED]
 Geodetic Research Laboratory  Web: http://www.unb.ca/GGE/
 Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142
 University of New Brunswick   Fax:  +1 506 453-4943
 Fredericton, N.B., Canada  E3B 5A3
 Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/
===

Problems with GLONASS Raw Receiver Data at Start of New Year

[Richard Langley]

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). Code measurements were back at 00:04:00.

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.

-- Richard Langley
   Professor of Geodesy and Precision Navigation

===
 Richard B. LangleyE-mail: [EMAIL PROTECTED]
 Geodetic Research Laboratory  Web: http://www.unb.ca/GGE/
 Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142
 University of New Brunswick   Fax:  +1 506 453-4943
 Fredericton, N.B., Canada  E3B 5A3
 Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/
===

Report of Leap Second Problem with GPS Data

[Richard Langley]

FYI.
-- Richard Langley
   Professor of Geodesy and Precision Navigation

===
 Richard B. LangleyE-mail: [EMAIL PROTECTED]
 Geodetic Research Laboratory  Web: http://www.unb.ca/GGE/
 Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142
 University of New Brunswick   Fax:  +1 506 453-4943
 Fredericton, N.B., Canada  E3B 5A3
 Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/
===

-- Forwarded message --
Date: Fri, 13 Jan 2006 09:59:31 +1100
From: [EMAIL PROTECTED]
To: [EMAIL PROTECTED]
Subject: [IGSSTATION-760]: DARR and 1Hz data from ARGN

**
IGS Station Mail  12 Jan 14:59:42 PST 2006  Message Number 760
**

Author: Michael Moore

  Geoscience Australia
Australian Regional GPS Network
  Geodetic Operation

ADVISORY:

High rate data, 1Hz 15 minute files, from the ARGN suffered a software
problem due to the recently introduced UTC leap-second. Data from DOY 001 to
DOY 009 is 1s off in the timestamps reported n the RINEX files. This problem
only applies to the 1Hz 15minute files submitted from the ARGN. The software
problem has been fixed, and all files from DOY 010 is reporting the correct
time.

RINEX headers for DARR from DOY 009, was incorrectly reporting an antenna
height of 0.000. The headers have now been fixed to report the correct
antenna height of 0.0025, and the data from DOY 009 has been resubmitted with
the correct header information.

I apologise for any inconvenience this may cause.

Regards
Mike

*
Michael Moore
Geodetic Operations
Geoscience Australia Earth Monitoring Group (GEM)
http://www.ga.gov.au/
Telephone: (+61 2) 62499052
Fax: (+61 2) 62499929
Email: [EMAIL PROTECTED]
GPO Box 378
Canberra ACT 2601
Australia
*

Diagram of CHU Leap-Second Recording and "Atomic" Clock

[Richard Langley]

I recorded the audio of the 3330 kHz signal of the National Research Council
of Canada's time signal station CHU from a few minutes before, until a couple
of minutes after, midnight UTC on New Years' Eve. A PDF of the annotated
sampled-signal time series between 23:59:00 and 0:00:01 can be found here:
. The leap second was
correctly inserted. However, starting one minute after UTC midnight, DUT1
became +0.4 seconds rather than +0.3 seconds as prescribed by IERS. The +0.4
second value continued to be transmitted until some time on 3 January 2006.
According to an NRC staff member, the problem arose because the IERS Bulletin
D announcing the +0.3 second value was not sent out until 28 December and
was not seen until people returned to work on 3 January after the holidays.
This problem seems to have occurred with some other time signal stations too.

Simultaneous with the audio recording of CHU, I videotaped the display of a
SkyScan "atomic" clock, model 31981, marketed by Equity Time U.S.A., which
receives the WWVB signal. It did not account for the leap second at UTC
midnight. Likely it continued that way until it next tried to receive the WWVB
signal.

===
 Richard B. LangleyE-mail: [EMAIL PROTECTED]
 Geodetic Research Laboratory  Web: http://www.unb.ca/GGE/
 Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142
 University of New Brunswick   Fax:  +1 506 453-4943
 Fredericton, N.B., Canada  E3B 5A3
 Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/
===

Leap Second in GPS Receiver NMEA Log

[Richard Langley]

Here are the logged NMEA $GPZDA messages from a ublox Antaris SuperSense GPS
receiver:

$GPZDA,235955.00,31,12,2005,00,00*6D
$GPZDA,235956.00,31,12,2005,00,00*6E
$GPZDA,235957.00,31,12,2005,00,00*6F
$GPZDA,235958.00,31,12,2005,00,00*60
$GPZDA,235959.00,31,12,2005,00,00*61
$GPZDA,235960.00,31,12,2005,00,00*6B
$GPZDA,00.00,01,01,2006,00,00*62
$GPZDA,01.00,01,01,2006,00,00*63
$GPZDA,02.00,01,01,2006,00,00*60
$GPZDA,03.00,01,01,2006,00,00*61
$GPZDA,04.00,01,01,2006,00,00*66
$GPZDA,05.00,01,01,2006,00,00*67

-- Richard Langley

===
 Richard B. LangleyE-mail: [EMAIL PROTECTED]
 Geodetic Research Laboratory  Web: http://www.unb.ca/GGE/
 Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142
 University of New Brunswick   Fax:  +1 506 453-4943
 Fredericton, N.B., Canada  E3B 5A3
 Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/
===