[teqc] strange Leica 1200 conversion

Lou Estey lou at unavco.org
Wed Oct 21 11:20:20 MDT 2009


Dear Matt,

>> 2. more problematically, when I then try and window that big RINEX 
>> file into a day RINEX files, I get occasional errors of the kind
>>  
>> teqc -st 20090606000000.0 +ds 86399 kns10910_all.09o >! kns11570.09o
>>
>> ! Notice ! setting TIME OF FIRST OBS to match requested window: 2009 
>> Jun  6 00:00:00.000 ! Notice ! NAVSTAR GPS: bad PRN= 42 being rejected 
>> @ 2009 Jun  6 12:32:00.000 (min= 1, max= 32)
>>
>> teqc: teqc windowed: delta = 86399.000 secfailure to read 
>> '                                G42G61' on line 5461503 of 
>> 'kns10910_all.09o'         (invalid satellite number) ... exiting
>>  
>> G42 and/or G61 appear every now and again. [...]
> 
> Clearly we need to find out what's going on in these epochs.  I'll
> need some sample to examine.
> 
>> Any desire to look at this file? The other 2 or 3 files I have also 
>> give similar, so not just a single receiver it seems.
> 
> If the problem can be isolated to a small enough chunk of the full
> 300 Mb file, I'd be willing to look at, say, 1 Mb worth.

(Ok, I had to get the full 300 Mb file.)  The interesting thing is the
epoch/SV lists around that epoch are:

  09  6  6 12 31 40.0000000  0 14G08G10G24G06G03G21G27G15G18G07G29G19
                                 G28G26
...
  09  6  6 12 31 50.0000000  0 14G08G10G24G06G03G21G27G15G18G07G29G19
                                 G28G26
...
  09  6  6 12 32  0.0000000  0 14G08G10G24G06G03G21G27G15G18G07G29G19
                                 G42G61
...
  09  6  6 12 32 10.0000000  0 14G08G10G24G06G03G21G27G15G18G07G29G19
                                 G28G26
...
  09  6  6 12 32 20.0000000  0 14G08G10G24G06G03G21G27G15G18G07G29G19
                                 G28G26
...

therefore the last two GPS PRNs are almost certainly supposed to be
28 and 26 for these five epochs.  The code in teqc is doing exactly
the same thing reading all the MDB data records 119 (0x77), so I would
assume that this must be an error in the record 119 for epoch
12:32:00 itself -- unless someone at Leica can demonstrate otherwise
(e.g. Leica demonstrates that the parsing in teqc of this one record 119
is wrong.)  The receiver info is:

[2041] teqc -notice +meta *.m00 | grep ^rec
receiver ID number:      480104
receiver type:           LEICA GX1220+GNSS
receiver firmware:       7.02

Currently the code in teqc for reading Leica's MDB record 119 is
not doing any sanity check on validity of the reported GNSS satellite
IDs -- because before this I had never seen a case where it was necessary --
but maybe one should be added given this example.

--------

Also, getting back to the original task that was being attempted:
daily RINEX files from the multi-month Leica MDB .m00 file.

Matt, why don't you use the new -tbin option to directly create the daily
RINEX?  E.g.

teqc -notice +obs + -tbin 1d name *.m00

The PRN problem is very intermittent, so some of the daily RINEX files will
still have the bogus GPS PRNs, but the majority with be AOK.

cheers,
--lou


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