Garmin GPSMAP 66sr and Centimeter-Accurate Positioning

[GPSrChive]

So does it mean, if I turn off Multi-band then I should receive more Galileo Satellites? Of course without Multi-band it is worse, but just out of curiosity.

Disabling Multi-Band may cause the device to track more Galileo satellites, but even then only a maximum of twelve signal bars will be displayed across the screen, the same number of signals being tracking with Multi-Band enabled in the example above.

What is the reason, that there aren't 12 GLONASS signals? I mean it is also a GNSS.

The number of tracked satellite signals depends on multiple factors, primarily the number of satellite signals available at any given time and location for the desired constellation. Trimble GNSS Planning is one of our favorite methods for viewing satellite constellation availability.

Additionally, it has been observed by many users that using 'GPS Only' frequently provides better accuracy than when using 'GPS + GLONASS'. The only reason we would enable 'GPS+GLONASS' on our Garmin devices would be if there were an insufficient number of 'GPS Only' satellite signals available and 'GPS + Galileo' was not an available option.

[mimichris]

Yesterday little hike I disabled the multi-band for a few minutes, the number of GPS, Galileo and Glonass satellites remains the same, with or without multi-band, the number of satellites always seems limited, Galileo the most is 7 satellites. Glonass between 5 and 7.
While on my multi-band smartphone, the number of satellites is unlimited and there are many of them, on the other hand I don't know their real efficiency.

[GPSrChive]

Yesterday little hike I disabled the multi-band for a few minutes, the number of GPS, Galileo and Glonass satellites remains the same, with or without multi-band, the number of satellites always seems limited, Galileo the most is 7 satellites. Glonass between 5 and 7.

Using the link we provided in a previous response, we were able to quickly ascertain that there were several times just today that the number of available GPS satellites would be nearly twice the number of available Galileo satellites.

Available Attachments

Available Satellites 01.png

While on my multi-band smartphone, the number of satellites is unlimited and there are many of them, on the other hand I don't know their real efficiency.

May be that the 'smart' phone is displaying satellites that are not actually available or visible from your current location?

[mimichris]

Would the same study give the same results with 67?

[JungleJim]

Would the same study give the same results with 67?

With the current state of the RINEX data on the 67 with software version 4.80 I do not think it is possible to do the analysis the authors of this paper did.

[mimichris]

Indeed the RINEX file is unreadable because full of bugs. I hope it will be corrected, but for that you have to file a complaint with Garmin, I don't have a 67 so I can't do it.

[Willie]

I was going to buy a 67 but the RINEX performance stopped me. I will wait until they get it right.

[SeeNoEvil]

Back in 2004 I played with getting RINEX files from the original yellow etrex (which I still have and still runs albeit with quite a few dead lines on the screen). I got RINEX but I don't think I managed to post process successfully, Or if I did I didn't keep the evidence!

In 2012 I played around with it again and used the Canadian's CSRS-PPP online processing to get some kind of results.

In the last few weeks a conversation with a friend led me back to this and I bought a RS232 to USB adapter and once again went around the block a few more times with the now ancient etrex, See the GarminBinaryTools repository on GitHub.

Of course I was also looking online at related bits and pieces and eventually stumbled onto the paper about the results from the 66sr a few years back. I also had not known about some of the more recent Garmin handhelds offering RINEX logging.

Couldn't stop myself really - and so ended up buying a used 66sr which I've now had for about three days. Really just so I could "play' with this whole thing again.

Today I finally got centimetre level results from a RINEX logging session yesterday of nearly 140 minutes in a very open spot. That was processed with rnx2rtkp (RTKLIB) from the command line using my nearest CORS type station (about 45 km away). So it can be done even if I'm not too sure what else to do with it!