This is what I’d do - just use one constellation and limit the constellation to nothing below 20 degrees above the horizon. There is 31 GPS sats in orbit, 27-28 operating depending on how many standby’s they got at any one time. You should be able to get 9 or 10 at any time that are higher than 20 deg above the horizon. You don’t need any more than that. 7 is all that’s required to shoot a precision approach for manned aviation receivers.
Who knows if they offset the clocks, or let them drift without correction in those other constellations on purpose at various times? Use what is proven and certified for manned aviation. If you move up north above the 55th parallel then may want to consider switching to Russian GLONASS-K2. The GLONASS sats orbit at 64.8 inclination with a period of 11.25. They have better accuracy north of the 55th parallel than GPS does. In the continental U.S. GPS with WAAS rules.
So these m8n’s are very popular for ardupilot, Is everyone who uses the GPS in default settings having this issue of refresh rate > 200ms and therefor Bad GPS Signal Health warning?
I guess I’m not really sure if they are or not. Haven’t really been keeping track of it. The problem is not really the M8N receiver. It is the fact it is built and the setup put in it at the factory in China. So they ship it configured to track everything in orbit, including probably space junk. So people start it up and it gets 17 satellites, or 19 or some ridiculous thing, and they think that’s really great. The more the merrier, and the better it must be. Right? Unless you understand how GNSS works, and then you’ll change that.
Yes, makes sense, large sat numbers look good until it slows your refresh rate to slower than 5hz, then you can’t arm and have bad gps signal health on your hud…
So now, how to change gps settings, off to google i go
Actually, the adjustments to change it, along with the explanation of the adjustment, should be right in your ground station. ArduPilot can configure the module.