[teqc] G00 appearing in RINEX from Trimble NetR9 .T02 files

Lou Estey lou at unavco.org
Fri May 28 15:53:20 MDT 2010

Simon (and any other NetR9 users),

> So out of the box it appears that Trimble's id code 76 is a NetR9, and
> they've introduced a new .dat/.tgd record 0x20 = 32 ... and what we're
> getting for the antenna ID is interesting. There's definitely new stuff
> here that we haven't seen with .t02 from a NetR8.
> More later as I dig into this.

Here's my analysis of that record (type 27, a data record).  "G00" (or "G 0",
if you are using an older teqc version) is what would show up in the RINEX SV
listing if teqc were expecting N SVs but there ended up being an inconsistency --
either a coding error or unanticipated problem with reading the data -- and
one or more SV numbers did not get populated and teqc ended up reading N-M SVs.

In this case, the record 27 for the epoch in question at 00:12:30 says there
should be 17 SVs in the record.  However, the first SV listed, an SBAS,
has a PRN of 0, which is clearly invalid.  Teqc correctly skips it, now
expecting 16 more SVs.  The data record for 00:12:30, though, has data slots
for 18 SVs (not 17), including a slot for the one invalid SBAS PRN.

So, here's the way I see the situation (though Trimble may disagree),
one of the following must be the cause of the problem for this particular
record: either

1) Trimble's runpkr00 v5.17 is at fault and the "number of SVs"
in record 27 should have been set to be 18 rather than 17 (in which
case teqc detects the one invalid SV number and skips it as it does
now), or

2) runpkr00 v5.17 is at fault and should have dropped the initial invalid
SBAS PRN in this record 27 so that there would only be 17 measurement
header/block segments in the record instead of the 18 in it, or

3) the documentation that I have for record 27 is an incomplete
description to cover this particular case, i.e. the "number of SVs"
says one thing but the number of measure header/block segments is
for a different number of SVs. (In which case, one does what?)

I don't see any other explanations.  Awaiting a response on these
possibilities from Trimble (who has your .t02 file) ...

BTW, we haven't (yet) seen this type of inconsistency with any NetR8 .t02
data translated to .tgd with runpkr00 v5.17.


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