[teqc] Ashtech Z12 spurious rollover bug

Lou Estey lou at unavco.org
Wed Nov 9 07:10:00 MST 2016


Thanks for this information, François.  This is a strange thing to happen
this GPS week (1922):

1922 (base10) == 0111 1000 0010 (base2)

If it had happened last week or the week before:

1921 (base10) == 0111 1000 0001 (base2)
1920 (base10) == 0111 1000 0000 (base2)

then one assume it had something to do with a base2 bit rollover.

Obviously the workaround for teqc users is to use the '-week' option with
the correct GPS week value.  (For anyone not familiar with this, see
'tip of the week' http://postal.unavco.org/pipermail/teqc/2016/002117.html )

Could you send me (not the list) a sample file from a Z12 doing this?

cheers,
--lou

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Louis H. Estey, Ph.D.              office:  [+001] 303-381-7456
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"If the universe is the answer, what is the question?"
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On 09-Nov-16 05:43 AM, François Meyer wrote:
> Hi,
>
> A number of Ashtech Z12 receivers had a spurious rollover event at the week boundary this sunday ; it makes them generate raw files with
> bogus (1024 week late) dates,
> both in the file name and the content.
>
> It looks as if firmware had somehow determined that 1999 aug 21 is still to come, therefore ceased to add 1024 to WN hence
> jumped back to 1997 march 23 (WN 898) instead of 2016/11/06 (WN 1922).
>
> Proper week number must be supplied as an argument to teqc
> at processing time. Data quality looks otherwise unaffected at that point.
>
> Our sample is :
> receiver type:           ASHTECH Z-XII3
> receiver firmware:       1L01
>
> but other colleagues have been affected, maybe with different
> flavors.
>
> Can this be fixed anyhow ? thanks,
>
> regards


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