Re: Report of Leap Second Problem with GPS Data
On Jan 13, 2006, at 6:26 AM, Richard Langley wrote: FYI. Thanks! Actual reports from the field, how novel! ** 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 won't claim to know the intrinsic importance attached to this. Critical systems may depend on the information. But is it fair to sum up the situation by saying that a leap second triggered a couple of bugs (or perhaps one common bug), they were detected, have been fixed, and affected data products have been remediated? Also, it appears that some other data products were unaffected? So, the issue has been resolved - would likely have been resolved sooner if a leap second had occurred earlier - and is no longer directly pertinent to a discussion of future leap seconds? Well done, Geoscience Australia! Rob Seaman NOAO
Re: Problems with GLONASS Raw Receiver Data at Start of New Year
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
Re: Problems with GLONASS Raw Receiver Data at Start of New Year
Rob Seaman scripsit: 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. I'd expect to see a wave of breakage as DUT1 exceeded 0.9s for the first time, and a second wave as it exceeded 1s for the first time. After that, of course, the problems would no longer be relevant. :-) -- They tried to pierce your heart John Cowan with a Morgul-knife that remains in the http://www.ccil.org/~cowan wound. If they had succeeded, you wouldhttp://www.reutershealth.com become a wraith under the domination of the Dark Lord. --Gandalf
Re: Report of Leap Second Problem with GPS Data
In message [EMAIL PROTECTED], Rob Seaman writes: I invite derision with my flights of rhetoric. As published papers [1] document, you have way to go. Poul-Henning [1] George August, Anita Balliro et all, study of Rotation of the Earth, approx 1993. (find it yourself). -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 [EMAIL PROTECTED] | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence.
