Gps constellation choices

There are a number of gps constellations. I am located in Ontario Canada. I am using the M2s with a Helical Antenna. Battery life is NOT an issue for me (although I’m not sure that is affected by constellations anyway).

I’m wondering which constellations I should be using or not using. Is there an upside or downside to reducing or increasing the choices?

What are others in this general area of North America using?

On a related note, in the web portal you can see a display that shows a selection of the satelites the M2 is latched onto. They have labels like C12 C34 E24 E33 G1 G30 R11 R21 S131 S138 etc. I assume these are individual satelites, but what do the letters mean?

Also, my status display often says it has locked onto 40 satelites, but there only a subset of that are ever displayed in the web chart. Where are the rest of them? Does this matter?

I am from Alberta.

I use all but QZSS that’s mainly for Japan / Australia.

C = China = Beidou
R = Russia = Glonass
E= Europe = Galileo (my favourite four atomic clocks per satellite)
S = Geostationary Reference Satellite, commonly used for SBAS Corrections, But not in the case of Emlid they are just using it as any other positional satellite.

It only shows the best, but still tracks the rest, for easier lock once they move to an optimal position. Emlid performs very well on mobile platforms like machinery.


You are an amazing source of info and help. Thank you once again.

I love Western Canada. I was born a Saskatchewan farm boy but my dad moved us to Ontario when I was still young. I continued to go west to help on the farm until I was 18. A girl changed my mind. I ended up marrying her and then spent my career Ontario’s auto industry. I bought a farm here when I retired.


If you go to this link

Enter your LAT/LON time zone and the time frame then go to the charts tab, it will show you what satellites are available in your location at whatever time. It should help you make that decision.


It didn’t seem to work on my android. But just before giving up, I switched to desktop mode. And there it was! Very very cool!

Thank you!

On Android there is a button that uses your phone location then go to the chart tab. Works on mine

1 Like

Enable all constellations. Better have too much data than not enough data.


That was my first thought.

However, it looks like I’m having a communications issue to the rover from the base over LoRa. So I’m trying to figure out how to improve the data transfer either through less data (fewer constellations), faster data transfer (different settings), fewer conflicts, or whatever.

See my thread at:

In any case, I can clearly see that the rover is not getting all the data it needs from the base because it is showing far fewer satellite locks on the base than the rover sees itself.

Thank you i am blushing :smiling_face_with_three_hearts: You can be too, just keep reading this forum.

I knew 0 about GNSS / RTK until i started reading this forum, and combine forum.
Emlids easy to use interface is an awesome learning tool for RTK.

Ive also learned enough about RTK survey i now have the “stick of truth” as well, for non legal boundary farmer survey activity. Everything is going to be properly drained and square to the world!


That’s the plan for me too. Just I’m a bit behind the curve compared to others like you.

I gotta confess that my read of the OpenGPS scared me a bit! I think it might be a case of knowing too much though… Steeringman talking to axle man talking to boss man talking to math man talking to gps man talking to engine man talking to… Then again, I might be reading WAY TOO MUCH into it.

Thanks again!


This topic was automatically closed 100 days after the last reply. New replies are no longer allowed.