Having them both on the same bus makes sense (mostly from a memory/resource standpoint). They would communicate successfully even if on separate busses.
@FarmerRob
I too have tried to set up a moving baseline and had the same issues as you. thanks to this post I too have been able to reverse the issues with the GPS. I am however wondering if you eventually managed to set up your moving baseline. I want to set it up on my large vtol and im curious what you have discovered.
i would appeciate any additional notes.
I’ve made two further attempts without success, but have not posted details for additional help. I’m working on tuning my rover and making some other progress (it drives!) and will circle back to this when I’m further along. One of my plans is to better isolate the antennas from RF just since with my test sled I haven’t fully eliminated that possibility.
On the bright side the steps in this thread reliably get me back to a functioning unit, so don’t be afraid to take a crack at the config. Please track your steps so you can advise if you succeed.
Rob
Shame. I too am going to try a few things to see if I can get it working. I’ll let you know if I discover anything.
The here+ GPS is l1 only ublox M8p, is it possible to do gps compass with it? I thought you needed a f9p to use it for yaw.
M8P modules can be used for moving baseline configs, but they are probably not a great option.
Nearly all of the problems in this topic are user error. We did discover a small bug during the course of troubleshooting, but it would not affect moving baseline configuration.
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I have some here + modules on the way so I will give it a go. My experience with the m8p is that they were very temperamental and rarely kept RTK fix. So I don’t know how much success I will have.
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Hi there, I exactly faced the same problem and your post saved my day after 4hours try and fail. Thank your very much!!!
Any success with M8P (Here3+) and moving baseline config? We were not successful so far…
@Yuri_Rage
Is there any way you could elaborate on why you think these are user errors. I have been trying now for some time to get this moving baseline working and i am unsucsessful. I have followed the wiki word for word and have three here3+ that i have used all combinations. Regardless I alway get a No gps after setting up MB. then the only way I can get my GPS signals back is to set GPS_TYPE=9 and go into the GPS parameters and change its type back to 1. I am no dev, but I can follow instructions and I am unable to get moving Baseline to work with the information I have available. Could you please help as I have a large VTOL that is having heading issues and I want to get MB working on it.
I dont think your going to have much luck with a M8p, RTK yaw will only work when it has RTK fix on both receivers and the m8p can only do that intermittently under ideal conditions. For reliable operation you need a dual band receiver. like F9P.
Thanks for the heads up, I appreciate it.
I would however like to ask, instead of going out and getting F9p systems, would it make sence to get a Here fixed base unit. would that work to solve my heading problem.
Or any other suggestions?
That will only help with absolute accuricy it wont help it get RTK fix. The m8p is just a poor RTK gps.
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We were also trying here to use Here3+ as MB.
Looking at the code, it checks if the GPS is an F9 to make the base configurations, so there is nothing implemented for the Here3/Here3+ M8P
I’m not sure why folks think M8Ps work in moving baseline in ArduPilot? Would someone please point me to a wiki page or something else that made you think that?
As stated above they dont work for moving baseline in AP. I’m not sure the ins and outs of why we never added them as moving baseline capable though.
Probably one reason is that you must have different ublox modules for rover and base.
And as @geofrancis said its not a great module for the moving baseline configuration. One unit must stay rtk locked with respect to the other one.
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That was my mistake, as I failed to differentiate between M8P-0 and M8P-2 variants. So this was admittedly a bit of a waste of time on all of our parts. I read the manual about a dozen times but missed the fine print.
I completely agree that there are better RTK-capable options than the now dated M8P.
Related discussion regarding HerePro modules and their F9Ps remains valid.
What would you recommend for a pair of GPS’s to go with this setup? Or the single unit with two antennas?
I have enough of the other kinks in my setup worked out that I’m wanting to come back to the moving base config and get better GPS’s.
Thanks,
Rob
A dual F9P configuration is the clear winner for performance.
I have not yet fully tested the single module/dual antenna unit from CUAV, but I can tentatively recommend it if your budget doesn’t support a dual module config. It worked very well on the bench.
Thanks. Going to order a pair and go from there.
Thoughts on Helical or plate/surveyor style antenna? I recall seeing surveyor style antennas on your mower, and I’m inclined to go the same route. I think on slopes or going over undulating terrain there might be a few situations where the helical antenna is better, but probably rare.
Edit: additional follow up Q:
Ok to go with the CAN version of the f9p?
I
All of that should work fine. I prefer the big survey antennas, but the smaller helicals are also fine, though they may be a little less sensitive.