GPSMAP 67 RINEX data

[mimichris]

please try to redo a Rinex recording and put it here to compare it with the one I had, to see if the management of the satellites has been improved. THANKS.

[JungleJim]

I did a new test today, partly the same route as the previous one. But as mentioned earlier, the issues with the RINEX data are unchanged 4.80. So I think any analysis based on this data is useless as the data is incomplete and incorrect.

67 4.80 RINEX data

grmn103j36.zip

I did receive a reply from Garmin Support Netherlands, but they referred me to the ideas form on the Garmin site as they do not have sufficient technical knowledge.

Does anyone know a better way to get into touch with knowledgable people from Garmin?

[mimichris]

Thanks, here is the result, there seems to be only Galileo and Glonass as satellites with an important stop.
Why are there only two satellite systems Glonass and GPS, Galileo is missing.

Spoiler

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PS: I can't put in spoiler. *** Yes you can - Read the Forum Rules at top of page to see how ***

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[Gadwin]

[...]
Does anyone know a better way to get into touch with knowledgable people from Garmin?

Some of th US support empolyees are quite good, but maybe you have to try several times to reach a good one.

[mimichris]

My impression is that they sacrificed accuracy to save battery power, besides there isn't even multi-band, which I can select on the graph.

[mimichris]

I did a new test today, partly the same route as the previous one. But as mentioned earlier, the issues with the RINEX data are unchanged 4.80. So I think any analysis based on this data is useless as the data is incomplete and incorrect.

67 4.80 RINEX data

grmn103j36.zip

I did receive a reply from Garmin Support Netherlands, but they referred me to the ideas form on the Garmin site as they do not have sufficient technical knowledge.

Does anyone know a better way to get into touch with knowledgable people from Garmin?

Did you set the multi-band correctly ? Was the 67 in energy saving because it seemed to me very strange this operation?
THANKS.

[JungleJim]

Did you set the multi-band correctly ? Was the 67 in energy saving because it seemed to me very strange this operation?

Device was in multi GNSS and multi band mode. Power saving disabled. I can do some more tests with only GPSS or multi-GNSS with multi-band off but as long as Garmin does not fix the RINEX data it will not tell us anything conclusive.

Thanks, here is the result, there seems to be only Galileo and Glonass as satellites with an important stop.
Why are there only two satellite systems Glonass and GPS, Galileo is missing.

I think you cannot base any conclusions on the result in RTKPLOT for the following reasons:

• the syntax of the satellite numbers of Galileo and BDS in the RINEX file are incorrect. So RTKLIB cannot parse this info and will not show it and therefore does not show BDS and Galileo data. If you look in the RINEX file you see Galileo data but the satellite number is just plain wrong, E4294967181 for example while it should be Enn.
• the data in the RINEX file is not complete. For GPS, BDS and Galileo only data of a single frequency band is present. Data for the other supported bands (L5 for GPS, Galileo, B2a for BDS) is simply not there. It is however shown in the satellite page on the device so I think the device is using this data.
• there are duplicate records for the same satellite. Probably RTKLIB will deal correctly with this, but the duplicates shouldn't be there.

So unless Garmin fixes these data issues, I think you cannot draw any meaningful conclusion about how the unit handles satellite data.

[mimichris]

It's true that I don't know much about RINEX, but I see that compared to the 66sr, the data is not the same and that there are significant interruptions, which does not exist with the 66sr. however I presume that Garmin has kept the same layout of the RINEX files of the 67 and 66sr, to do with another RINEX software if it exists.
The 66sr also uses satellites that aren't properly acquired which the 67 doesn't I guess it's power saving that does that.

[JungleJim]

In its current form, the RINEX data for Galileo and BDS does not conform to specification and there is no L5/B2a data in the file, data that the device for sure has available (because shown on the satellite page).

You can easily see this if you open the 67 and 66sr RINEX files in a text editor, as they are simple text files.

So somewhere on the device the conversion of available GNSS data into RINEX format goes wrong.

It may be that the 67 does some “tricks” to conserve battery life, but you cannot draw this conclusion on the current RINEX data since it is invalid and incomplete

It would be very interesting to compare valid 67 RINEX data to what is shown on the satellite page, but at the moment this is simply not possible.

[GPSrChive]

Does anyone know a better way to get into touch with knowledgable people from Garmin?

Just keep posting your observations etc. here, they have been directed to this thread.