[teqc] inexplicable value on Galileo Navigation Message

Mathieu Peyréga mathieu.peyrega at gmail.com
Fri Feb 1 07:15:50 MST 2019


Hello,

my GNSS station 
(http://rgp.ign.fr/STATIONS/logsheet.php?nom=magc_20181016.log) is based 
on a trimble board (bd970, and the rt27 to rinex streaming is done with 
teqc). It's tracking Galileo for a while now, but I've never seen this 
kind of message. Station is in metropolitan France and so probably not 
seing any IRNSS signals (and anyway, option is not activated on the 
firmware)

I'm keeping all .rt27 files in case and can provide them if needed for 
specific times.

Best regards,

Mathieu Peyréga
--
tel : +33 (0)6 87 30 83 59


Le 01/02/2019 à 14:56, Lou Estey a écrit :
> No one has commented on this in the last two days, either to this list 
> or to me personally.
> If you have any thoughts or comments about it, I suggest you try to 
> send me something very
> soon, or this particular bit of grizzle in the sausage (*) will remain 
> as part of RINEX
> creation in the next teqc release and may be around for a while after 
> that.
>
> cheers,
> --lou
>
> * see https://postal.unavco.org//pipermail/teqc/2018/002589.html
>
> On 30-Jan-19 07:34 AM, Lou Estey wrote:
>> dear Grégory,
>>
>>> Yes we track IRNSS SV also
>>
>> Then teqc's message of:
>> .dat 27/0x57-6: unknown SV type= 9
>> might be referring to the IRNSS constellation.  The last 
>> documentation I received
>> from Trimble on .dat/.tgd record 27 (or streaming 0x57-6) does not 
>> have a type = 9
>> defined, so this is something new that Trimble has added (for at 
>> least the Alloy).
>>
>> I have an email in to our contact at Trimble to get some 
>> clarification on this (and
>> two other questions).
>>
>>> You saying "it's due to limited information", does it mean that the 
>>> problem coming from receiver ?
>>
>> No, the receiver is almost certainly fine.
>>
>> This is one of those cases where the RINEX specification is asking 
>> for something
>> that's not available in the input "data" (the decoded Galileo 
>> navigation message
>> in the Trimble .tgd format, record 28) or not clearly evident (at 
>> least to me) from
>> the documentation on that "data" (the Trimble documentation on record 
>> 28).
>>
>> Where you're seeing a value of 1 for the "data sources", it's very 
>> clear from
>> Trimble's documentation that the source of that particular Galileo 
>> navigation message
>> is E1-B.  That much is 100% certain.  But, from what I understand, 
>> that's all that
>> can be known about this situation from the documentation.
>>
>> Then for RINEX, bit 8 or 9 of the "data sources" value could also be 
>> set, i.e.
>> from the RINEX spec:
>>
>> bit 8 set: af0-af2, ToC, SISA are for E5a,E1
>> bit 9 set: af0-af2, ToC, SISA are for E5b,E1
>> bits 8-9; exclusive (only one bit can be set)
>>
>> So in this case does one set bit 8 or bit 9?  I have no idea. Both 
>> bits cannot be set
>> (that much is 100% clear from the RINEX spec), so I didn't set either 
>> one.  And,
>> technically, not setting either bit 8 or bit 9 is totally valid given 
>> the current
>> RINEX spec for the Galileo data sources.
>>
>> --lou
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