Re:
http://ls.unavco.org/pipermail/teqc/2009/000790.html
subject: two new intermittent problems with TPS data
Topcon engineers took a look at the files that gave rise to
the problems teqc was having. For at least the first case
(i.e. apparent rogue value in [RC] messages), nothing was
really wrong with the [RC] messages. What was wrong was a
missing message, [SI], which gives the tracked satellites
for an epoch, or subsequent epochs if the list is unchanged.
The reason for the occasional missing [SI] message is that
the data was from a rover and a few random messages were
lost in transmission. When the missing message is the [SI]
satellite list when there's a change in tracking, esp. a
reduction in the number of satellites from a previous set
of epochs, this is a problem. The Topcon engineers suggested
some things that could be done to improve teqc's veracity
in reading corrupted TPS/JPS data, but my opinion is that
the simple fix I made in teqc seems to be "good enough" for
most cases, and, if users really want the full professional
treatment for problematic data they really should fall back
to Topcon's own translator tps2rinx.exe (for Windows only),
because, quite frankly, Topcon engineers are always going
to be far more familiar with their data than I am ever going
to be.
The second case (i.e. [SI] list show zero satellites)
apparently is allowed by the firmware but doesn't occur
often. And I was mistaken: previous teqc versions would not
crash when this condition occurred, but teqc would cleanly
exit when this was detected, but report a rather cryptic
message of:
teqc: cannot allocate memory for Topcon CA bin (0 bytes) ... exiting
As I mentioned before, now knowing that a zero satellite
list is a valid state in TPS/JPS, this was easy to fix.
-------------------
Next release: I'm still trying to get the same GLONASS nav messages
collected from different GNSS receivers to vet teqc's reading
of Trimble's new GLONASS nav record, but this test still isn't done
and I have no idea when it might be. If it isn't done in two
weeks, I'll go ahead and try to get out a new version of teqc
without this vetting.
-------------------
That's it for now ...
cheers,
--lou
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Louis H. Estey, Ph.D. office: [+001] 303-381-7456
UNAVCO, 6350 Nautilus Drive FAX: [+001] 303-381-7451
Boulder, CO 80301-5554 e-mail: lou unavco.org
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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