definitely always add SBAS (not because of the SBAS corrections, because of the observations)
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@bide, thanks for the crash course! This will help me a ton. Now, I will go melt my brain on the documentation whilst having a cold one. 
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In central USA, I am noticing I can also now use BEIDOU instead of GLONASS if you are having trouble with GLONASS. I always use SBAS along with GPS. Like @bide has mentioned before, SBAS counts as part of GPS when you select both. Obviously I use GALILEO too… not sure why you are using just GPS AND GLONASS ONLY? The more sats the better if in your range of course. I.e. Which is why i use SBAS and GALILEO also.
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For the record, I did several more iterations and only one of those was better by 0.1%
These were the settings in RTKPOST:
- Constellations: GPS only
- Filter type: combined
- Elevation Mask: 10 degrees
- Integer Ambiguity Res: Fix-and-hold
- the NAV file used was from the drone, not the base.
I also recoverted the base raw log to RINEX with Glonass disabled, then post-processing with all constellations enabled. It was the same outcome as disabling Glonass altogether.
Conclusion: There is some extreme Glonass interference in the base’s log file, causing the output to be less than it should be. The rover log file also has some Glonass-only interference, but not too bad. The post processing settings suggested here are only fit for this odd situation.
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All good stuff here. Be curious on result if using CORS data. Looks like you can get GPS+GLO throughout Texas. See if this is cleaner than your base data and compare results.
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Only problem appears to be your GLONASS data at the base is trash. GPS-only with 13° mask I get 97.4% fix, which is comprised of 100% fix during flight and some float on the ground when it doesn’t matter.
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Over a year or so of following Mr. @michaelL , I have noticed that in the beginning he was having odd trouble with GLONASS? If I recall correctly, for a while, he wasn’t using GLONASS? But you really need that constellation. I don’t know why he would have such a problem being in TX? Either way, I wonder if something is wrong with his Reach receiver that is operating as the BASE and GLONASS??? Maybe try BEIDOU instead of GLONASS and see if that resolves anything?
Personally I would be using (FOR USA):
GPS
SBAS
GLONASS (interchange BEIDOU when needed?)
GALLILEO
Instead of JUST GPS & GLONASS.
PS. Are there High Voltage Power Lines in the area? Maybe increase Elevation Mask Angle if down in a lower elevation with powerlines in the horizon?
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yeah that base data is not cool. seeing some more base files would give a better idea of whether the receiver is not tracking well. If it was a tallysman antenna i’d maybe accuse the groundplane of being unsuitable for GLONASS tracking or something??.
gotta be careful you don’t select a configuration that drops events.
My tracking is GPS+GLO+GAL and that is rock solid for me so far. I did see 6 events missed recently, even when using the Ashot with my P4 for a 200+ photo mission, even though this is not supposed to skip events. I don’t know if the skip is duet to satellites selected with M+, or Ashot.
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Agree, but I would definitely couple SBAS with GPS. Just don’t use so much RTCM3 messages/or too high Hz freq.
In his region, just seems these should be perfectly fine, I know they are in central US.
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Initially I was told to just run GPS only at 14Hz on the drone and that has worked fine, but I am finding that I can go a little further. Recent updates to reach view are allowing many more options.
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That’s a good idea. I will try one of our TXDOT stations.
No power lines. Hilly terrain, but the base is in a clear sky view. The only outstanding factor would be the lake and if there is some magnetic interference from the subterrain.
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Try BEIDOU instead of GLONASS also to see what you get. Also TXDOT CORS station.
Did you have (1) RS+ or RS?
Will do. I have RS+ Rover and Base and the M+ on the P4P.
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Using GPS only, gets you highest Update Rate of 14Hz and you mention it works “fine”… so curious why you want to drop Hz rate to 5Hz by adding constellations? I would assume the higher the update rate for fast moving rovers such as drone… but does 5Hz work just fine also for this in order to use more constellations for better FIX etc?
oh ok, you have (2) RS+ then… so then if one receiver is a problem with GLONASS…then you can try the other.
As you add constellations the allowable rate drops to 10Hz and 5Hz is plenty fast to capture data from two or more constellations.
It doesn’t matter which RS+ I use. I assumed the M+ gets better reception because it’s 200+ feet in the air.
I meant that if you have (2) RS+ receivers, 1 as BASE and 1 as ROVER…if the BASE one is faulty, then you can swap out with the RS+ ROVER to test. Yeah, I know the more constellations you use the lower the update rate becomes… was just curious since GPS 14 Hz only was working for you?