[ANSS-netops] [EXTERNAL] Re: Altus/K2 timing issue

[Paul Friberg]

Hi All,

For those who are still using K2's there is a new fix to the k2 gps
rollover now in the Earthworm SVN repo.  The code can be downloaded using
the SVN instructions at:

http://earthworm.isti.com/trac/earthworm/wiki#EarthwormSubversionRepository


The revision that fixed all issues was r7541 and this has been tested with
64-bit Earthworm against a K2.

Best regards,

Paul

On Tue, Jul 3, 2018 at 12:13 PM, Meremonte, Mark <mmeremonte at usbr.gov>
wrote:

> Hi Jon,
>
> Think will set GPS power on and time length power on to 0,0 to keep GPS
> off & set manual time temporarily.   Thank you very much for the fix!
>
> Regards,
> Mark
>
> *********************************************************
> Mark Meremonte         Geophysicist
> U.S. Bureau of Reclamation:  Seismology, Geomorphology, and Geophysics
> Group
> Denver Federal Center            Work: 303-445-3298  Cell: 303-808-3894
> POBox 25007, 85-833000      Email: mmeremonte at usbr.gov
> Denver, CO  80225                  Web: http://www.usbr.gov
> Ship:  U.S. Bureau of Reclamation, DFC, Bldg. 67-10th Floor, Denver, CO
> 80225
> **********************************************************
>
> On Tue, Jul 3, 2018 at 9:30 AM, Jon Rusho <jon at seis.utah.edu> wrote:
>
>> We've run into some glitches with getting the fix merged into the
>> Earthworm svn repository.   The fix is pretty simple--check to see if the
>> data is timestamped between Nov 1998 and July 2018 and add an offset if it
>> is.   The code snippet for outptthrd.c is below, with the existing lines
>> before and after.   This has been tested in k2ew version 2.43, on Ubuntu 14
>> 32-bit.   We're still trying to get it to work with the latest & greatest
>> 64-bit version of Earthworm.
>>
>> ----------------
>>       starttime = (double)(timestamp + K2_TIME_CONV) + (double)msec *
>> 0.001;
>>
>>    /* check for 1024 week rollover glitch 2018/2019   jr 01jul2018 */
>>       if (starttime > 911143558 && starttime < 1530403744 )
>>       {
>>         starttime += 619315200;   /* add 1024 weeks of seconds */
>>
>>       }
>>
>>
>>       /* Check packet time; reject packets older than 1981, which would
>> mean
>> ----------
>>
>>
>>
>>
>>
>>
>> On 7/2/18 2:49 PM, Jon Rusho wrote:
>>
>>> We've done some testing with an impacted K2 using software-based time
>>> correction and a Nanometrics Centaur.   Both were fed the same square-wave
>>> input signal and compared.
>>> Attached are two tracings from Swarm.   The left one is from the K2 with
>>> software correction, the right from the Nanometrics.   The red vertical
>>> line shows the same time in both windows.
>>>
>>> For Earthworm users, I'm working with ISTI to get the code change put
>>> into the svn repository.
>>>
>>> Note: the reason this rollover glitch hit early is based on the last
>>> firmware revision from Kinemetrics.   The firmware fix for the 1999
>>> rollover was put out 40 weeks before the actual rollover.   That fix
>>> expired 40 weeks before the upcoming actual rollover in 2019.    Also, this
>>> doesn't seem to impact all K2 and Etnas.   20 of our K2's were hit, but
>>> another 20+ are fine.
>>>
>>>
>>> --jon
>>>
>>> On 7/2/18 9:44 AM, Jon Rusho wrote:
>>>
>>>> UUSS experienced an early roll-over of the GPS 1024-week counter in
>>>> many of our Kinemetrics K2 instruments this weekend.   Looking at IRIS,
>>>> this appears to have also impacted other networks.   The problem manifested
>>>> itself as waveform data being timestamped in 1998 instead of 2018.
>>>>
>>>> I'm testing a software fix in the k2ew Earthworm modules.   For data
>>>> that comes in timestamped between 1998 and 01-July-2018, I shifted the time
>>>> by 1024 weeks (619315200 seconds).
>>>>
>>>> My question to all of you, is this the correct shift or am I missing
>>>> something?
>>>>
>>>>
>>>> More info on the GPS rollover: https://spectracom.com/resourc
>>>> es/blog/lisa-perdue/2018/gps-2019-week-rollover-what-you-need-know
>>>>
>>>>
>>>>
>>>> Thanks
>>>> --jon
>>>>
>>>>
>>>>
>>>>
>>>>
>>>
>>>
>>
>> --
>> ===================================
>> Jon Rusho
>> Seismic Network Engineer
>> University of Utah Seismograph Stations
>>
>> jon at seis.utah.edu
>> 801-585-5523
>>
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>
>
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