Hello, I am trying to connect three vehicles (quads running Arducopter on Pixhawk Cubes) to QGroundControl using RFD868ux radios. The radios are running standard point to point firmware so I have three pairs. The ground radios are connected to a desktop via USB hub.
So, to begin with, with default settings (only difference is NetIDs which are unique to each pair and the SYSID_THISMAV param, which is unique to each Pixhawk) the performance is horrible. A single vehicle is OK. With two, some commands get dropped and you can tell the difference but it’s kind of OK. With three, forget about it, a command might get through occasionally but by and large, it’s hopeless.
I have searched online but cannot find anything on what settings are best for such a setup. I have fiddled around and got somewhat better results by doing the following but have found nothing really definitive yet:
Increasing hopping channels (default is 1, increased to 7).
Shortening the duty cycle (default is 100%, shortened it to 10%)
I am also considering:
Adding Listen Before Talk (not sure what value).
Manually assigning a unique frequency range to each pair.
Perhaps flashing with multipoint firmware.
Before I go fumbling blindly, does anyone have any tips on what settings to play with? The RFD radios have astonishing performance when used in a single vehicle and I 'm sure using them in multi-vehicle setups couldn’t be that hard.
I suspect you are getting radio interference by having 3 radios right next to each other on the ground.
Setting each radio to operate in a unique frequency range will help with interference but you will loose a lot of your data bandwidth, so your coms might be slow.
I have not done any multi vehicle setups so I cannot offer any insight into those settings.
Are you getting steady telemetry data from the 3 aircraft?
With the 7 channels and 10% duty cycle I get reasonably steady data but it’s nowhere as good as single vehicle. QGC shows the radio status including an “Rx errors” field. In a single vehicle setup, the errors are typically 0 or 1 and don’t change much. With 3 vehicles, I see them going up at around 4-5 errors per second.
Thank you Shawn, I will definitely look into that. However, I am puzzled that I have not seen anything about SiK settings on the web. For example, look at Ardupilot’s own documentation here. As far as I can tell, these are three vanilla radios, not running multipoint, ridiculously close to each other, seemingly without any problems. I am guessing that if that setup needed extensive fiddling with the radio params, it would be mentioned somewhere.
So, just to close this thread, I tried multipoint and the setup was fairly straightforward. I assigned a unique node id to each radio and then on the master node, did AT&M0= 0, Z, where Z is the number of nodes. It worked fairly painlessly, however, I have reverted to P2P so never got round to testing at range.