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

[Meremonte, Mark]

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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