Hi All, I have used RTK a fair amount using the Here+ system and the normal waiting as the Base station surveys itself in. If I connect to an NTRIP service on MP can I get rid of the base or is a base GPS still required? I am using an F9 chip on my drone (Ardusimple).
You don’t need a base, that’s what the Ntrip station/server does. It’s best if there is one relatively close.
Awesome, thank you. That’s what I was hoping for.
Depending on your application “close” means less than 20km (possibly even within 10km). I have one about 40km away that I occasionally use, but it doesn’t provide accurate enough results for anything other than a quick test of RTCM3 messaging.
Interesting. I have heard others talk about the errors from using a base that is too far way. I have been using one that is 41 km away for months and have not noticed any issues. I might just be lucky or my tuning isn’t good enough to distinguish the difference from a GPS error and a wobble caused by tuning. I have purposely kept my mowing a little further from objects than when I had an onsite base, just to be sure.
I should have a base back onsite in the next week or so. Maybe I will see a difference.
EDIT: I wonder if the type of GPS at the base end can make a difference. I have an F9P as the base located 41 km away. I upload to www.rtk2go.com.
I use a commercial station that I found via the same website. It’s generally very good, but occasionally, while remaining in RTK Fixed, I’ll see a position jump of 2-3 feet, almost always perpendicular to the direction of travel. With a 48" lawnmower, 2-3 feet of position error is too much. My own ArduSimple-based fixed base is more reliable.
Interesting. I have not seen that. I have seen that kind of jump when I drop to RTK Float, usually when I am under a tree. I have MP announcing the RTK status when it drops below 6 (RTK Fixed) and I switch to manual until it goes back to RTK Fixed. hmmm - need a script to do that! 
If it jumps maybe you momentarily lose connection to the ntrip service. If the shortage is 3-4 seconds the unit stays in fixed but the position may jump a bit.
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Perhaps that’s the case. It’s the only station I can access locally, and I do enjoy having it available for testing, but I’ll stick with using my fixed base station for practical purposes. I just ordered some better antennas for the whole setup, which I’m hoping improves things even more.
@ktrussell, I’ll put some more work into that script today. It’s close to ready, but that’s for another thread…
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