[teqc] TPS conversion problem

[Lou Estey]

hi Rui,

>> Sorry... Forgot to tell that I was using the latest version. The problem
>> still occurs:
>>
>> <geodac#/home/gpsdata>teqc -version
>> executable: teqc
>> version: teqc 2010Oct21
>> build: Linux 2.4.20-8|Pentium IV|gcc -static|Linux|486/DX+
>>
>> <geodac#/home/gpsdata>teqc +err /dev/null -sv_reset -top tps
>> /media/NETS/REPANGOL/RAW/30s/2010/300/BNGL/BNGL1027* > BNGL3000.10O
>>
>> <geodac#/home/gpsdata>teqc BNGL3000.10O > /dev/null
>> ! Notice ! 2010 Oct 27 05:46:30.000: poss. incr. of sampling int. OR data gap of 480.000 seconds (min. dt found= 30.000 s)
(lots more of the same type of gap message)
>> ! Notice ! 2010 Oct 27 09:31:00.000: poss. incr. of sampling int. OR data gap of 1020.000 seconds (min. dt found= 30.000 s)
>>
>> I also noticed this repeats more or less on the
>> same time of the day (not exactly the same epochs) day by day...

>>>> This repeats for other days and other stations.
>>>>
>>>> In order to try to detect the problem, I also used tps2rin (the tool
>>>> provided by Topcon) to convert the files and the merged file does not
>>>> show any data gaps. So, I really suspect that there is some issue in the
>>>> raw data (TPS) of the new Topcon receivers when translated with teqc. Is
>>>> this related with the issue that you detected last year concerning the
>>>> Javad/Topcon format?

This turns out to be very straightforward -- just not obvious -- and I've
answered the same question for other modern receiver types for many users
individually.  You're using a Topcon receiver (Net-G3A) where the maximum
number of trackable SVs is not known by teqc.  What you have to do here is
tell teqc a reasonable maximum with the '-max_rx_SVs' option, e.g.:

[3828] teqc -max_rx_SVs 24 +mds bngl1027f.tps
! Notice ! GPS week in Topcon [UO] = 583; (default) GPS week = 1607
! Notice ! GPS week initially set= 1607
2010-10-27 05:00:30  2010-10-27 06:00:00    224848  bngl1027f.tps

i.e. now no more gap messages.

Teqc's code is currently set to only allow a maximum of 20 SVs for the
following Topcon rxs:

                 "TPS LEGACY",
                 "TPS HIPER_GD",
                 "TPS HIPER_GGD",
                 "TPS HIPER_LITE",
                 "TPS HIPER_PLUS",
                 "TPS ODYSSEY_I",
                 "TPS ODYSSEY_E",
                 "TPS GB-1000",
                 "TPS GR3",
                 "TPS E_GGD",
                 "TPS EUROCARD",
                 "TPS NETG3",
                 "TPS NET-G3A",

Part of the problem for some receivers, and at least some of the modern Topcon
rxs fall into this category, is that there are a maximum number of "channels"
allowable in the firmware, where a channel here is essentially some specific
signal (e.g. L1C/A, L1P(Y), L2P(Y), L2C, L5, ...) on a specific SV, but this doesn't
map well into a fixed upper number of trackable SVs because the maximum number
of SVs now depends on what you've set the receiver to track.

So, if anyone is using a modern receiver, and you are seeing a number of 'gap'
messages like the above, and a '+diag' of the raw data is not showing any
known data corruption, then try gradually increasing the trackable SVs number
with '-max_rx_SVs' and see if that fixes things.

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
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~