I am trying to send RTK correction (Sparkfun Base Station F9P) to a here3+ (connected to my ardupilot) using mission planner (RTK inject). I tested the RTK base, which works fine with another RTK rover (14mm precision). When I try to connect it with the here3+, it seems to receive the messages (fast green blinking lights), but it doesn’t get “Fix,” and the HDOP is huge >1m.
I tested the Here+Base to send the corrections, and as soon as I turned it on, the mission planner showed the GPS status as fixed. Among other things, I noticed that it sends a package called NMEA String.
For my base station, I am sending RTCM (1074,1077,1230, 1005, 1094, 1124, 1084), but I haven’t found an option to send this NMEA string. Can anybody tell me which messages are required from the here3+? would it be possible to use the RTCM messages instead?
Let me describe it better. The RTK reference station I have is this one (Sparkfun ref station). It is a fixed surveyed antenna that sends RTCM packages to rtk2go.com. With an external RTK GPS connected to SW Maps, I can reach 15mm precision when sending the RTCM packages. So I think my reference station should be okay.
I want to send the corrections to my here3+ using Mission Planner or RTKLib (or anything similar), but the precision isn’t getting any better than (hdop) >0.8m. I noticed today that the here3+ only sees ~14 satellites, and the status is always “3D DGPS”.
Since I cannot use the here3+ to communicate with Ublox, it is hard to figure out the real problem. It’s worth mentioning that I am new in this area, so please feel free to correct any misassumption I may be considering.
Besides any feedback you may give, I was wondering:
How many satellites would be the minimum for a decent RTK reception?
What packages (messages) does here3+ need for RTK correction?
is the RTK inject in MP suitable for send fix reference station corrections?
I think you’re simply asking all the wrong questions.
If you have a base station that’s already providing an RTCM3 stream to RTK2Go, use Mission Planner to connect to RTK2Go:
When you click the connect button, you’ll see the “remote host” dialog pop up.
Replace my example with your own email address (my example would be user@email.com, but note the use of “-at-” in place of the symbol).
You can leave the password as “none” - no password is required to connect as a client.
Replace MOUNTPOINT with the name of your station.
As for Here3+ precision…it’s kind of trash. The old M8P module never worked all that well for truly precise applications. You should at least be able to achieve an RTK Float solution with it, and occasionally RTK Fixed, but if you’re expecting great results, prepare to be underwhelmed.
I am using it precisely as you described, but I cannot even reach RTK Float (it keeps in 3D DGPS).
Is the here4 (F9P) any better? I don’t need 10mm precision, but definitely I need better than 1m (I was wondering at least 10cm). Would you suggest any RTK device other than here+?
To get corrections over to the Here3+, you’ll need to have it configured on an autopilot that is running ArduPilot and connected to the same instance of Mission Planner.
And you absolutely NEED to have that autopilot and GPS outside with a clear sky view!!!
All that said, the Here4 is considerably better, but it uses what I consider to be an inferior Neo-F9P chipset and has some serious firmware flaws at present.
Thank you for checking my base station. I had the same result here. I was wondering if I was missing something. I will get a clear space and try it again with my here3+
I will defenentely get this Holybro. Would the helical version be much better for the signal than the rover one?
