I’ve recently brought a few bits to make a 4g controlled plane following guides online and I’m having difficulties. Also I’m not sure if this is the correct forum category for this. hopefully, it’s ok.
I have a Sixfab 4g hat for my Raspberry pi to connect to mission control using Mavlink, which is connected to a Pixhawk. The guides I’ve followed are a little over my head to be honest but I’ve dabbled in programming so I figured I could give it a crack. Unfortunately, the guides I’ve found are rather outdated and despite my best efforts I’m unable to get it working properly, so my question!
Is there an up-to-date guide to control my Pixhawk drone over 4g to my ground station running mission planner?
Additionally, I’m interested in including openHD in the build as well.
For LTE you need some way of accessing the air module, be it public IP, VPN or reverse proxy. Other than that you have to configure Ma router or mavproxy to expose a port onto the internet (I would advise either firewalling the hell out of the connection or using some tunnel with authentication).
Everything else is routing at MavLink layer.
Using mavrouter route the telemetry to OpenHD software airside and merge the streams groundside.
I’ve done that sort of thing a few years ago using 3G/4G wireless broadband dongle.
As Lupus mentioned, a network tunnel is required unless you’ve managed to somehow get a SIM with a fixed IP address.
Other important thing:
As you are not just using telemetry but actually controlling the aircraft I would be inclined not to use UDP but rather TCP in order to avoid data packet losses.
The difference there is (besides protocol) you have to initiated TCP from Ground-Station.
(UDP is initiated from aircraft)
Zerotier has configuration software for all platforms available and so certainly ca be setup on RPi.
Mavlink is designed to work on unreliable links. Using TCP may introduce significant latency if some frames are lost as TCP guarantees order of delivery. Drone doesn’t care about RC_Override that was sent half a second ago if it got one from 100ms ago.
Tunnels introduce not insignificant latency. Acceptable for the command link less so for control. If possible get Public IP SIM.