[teqc] Old Ashtech receivers have stopped working

Lou Estey lou at unavco.org
Wed Dec 7 09:04:54 MST 2016


On 07-Dec-16 06:59 AM, Joe Sass wrote:
> Hello Lou,

> A few weeks ago, many of our old receivers (Z-Surveyor and LOCUS for example) started collecting raw data with bad time stamps and
> unprocessable data.  In reading some of the threads and speaking with colleagues, your name was mentioned as possibly understanding what
> changes have taken place or what cusp has been crossed to cause these failures.
>
> Do you have any ideas about this?  I am more curious than worried.  Most of the receivers in question have outlived their discontinuance by
> more than a decade.
>
> Thank you in advance for your insights.
>
> --
>
> Best Regards,
>
> Joe Sass
> Channel Development Manager, Geospatial
> 935 Stewart Drive | Sunnyvale, CA 94085
> joe_sass at spectraprecision.com <mailto:joe_sass at spectraprecision.com>

hi Joe,

Here's what I know:

I first heard about week problems with the Ashtech Locus last week when a user reported
that a set of them were recording the date to be the week of 13 Apr 1997.

Last week was GPS week 1925 and 1925 - 1024 = 901, which was the week of 13 Apr 1997.

This situation is very much like the same thing the happened to two other sets of receivers
this year; the problems with those receivers (below) started on Sunday right after the
end-of-week rollover.

The first was when Trimble 4700s (and maybe a few of older Trimble models?) started
recording the week wrong by -1024 weeks starting on 14 Feb 2016.

The second was when Ashtech Z-12s and variants started reporting the week wrong by -1024 weeks
starting on 6 Nov 2016.  (see http://postal.unavco.org/pipermail/teqc/2016/002185.html)

Now you've included the Z-surveyor (which I believe is related to the Z-12, at least
roughly the same vintage).

The commonality is that these are all older receivers with, essentially, unsupported firmware.

I've been told by teqc users (engineers here at UNAVCO and other users) that at least
with raw data from the Trimble 4700s and the Ashtech Z-12s that if you use the '-week' option
with the correct GPS week to read the raw data, using a week value for when the data are
actually for (but not based on the file name or what teqc reports using '+mds' or '+meta'
on the raw data from the receiver), then teqc will correctly translate the raw data into RINEX.

Hope this helps.

cheers,
--lou

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Louis H. Estey, Ph.D.              office:  [+001] 303-381-7456
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      WWW:  http://www.unavco.org   http://jules.unavco.org

"If the universe is the answer, what is the question?"
                                                -- Leon Lederman
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