Long distance operation


I am searching for a way to communicate with my plane from the ground, long distance away, like 10km.

I saw many people use dragonlink system for both controller radio and telemetry/command(MAVlink) link.
However, it seems it is not allowed to use them in Japan, even with license. (This part, I am actually not so sure yet… trying hard to confirm if it is really true.)

In the mean time, I believe there should be some general purpose and legally compliant modem modules in Japan. But I don’t know what kind of spec parameter and configuration I should look at. Like…

  • what kind of bandwidth/bitrate is required for PX4 datalink system?
  • do I just need modem modules with UART interface? Or do I need a micro controller between modem and Pixhawk and load some kind of interfacing firmware? (Sik??)
  • How about the controller radio? Can I use one modem for handling both radio control input and telemetry/command(MAVlink) ? Or do I need to modems?

I actually got a license associated to myself (not to products) for commercial purpose telecommunication; and this allows me to use transmitter of 1W power, for example. (Without license, it is up to 10mW only)
Therefore, I believe that as long as there are right modules/products connected and set up, I should be able to do this long distance operation.

I dare to start this long distance operation in Japan, but I’m stuck at this problem.
Can anybody give me some comments?

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If you’re using QGroundControl, you can use the Joystick interface to send control commands that way. Just plug your transmitter into your laptop and use as a joystick. Once you’ve got that link going, any long range serial link could be used eg: Microhard pDDL - assuming you’ve got room for it. Expensive though and possible import restrictions.

Have you considered crossfire? I believe that supports mavlink.

For the communication you could use a RockBlock iridium module. But this would only work for auto missions and would give you a small update message around every 30 seconds. In addition it is quite expensive as it has a running cost but you would have no constraints on the distance to your ground station.

You can check with Helibatics or 4Gmetry.

Good luck.

Thank you for your answer and sorry that I respond so late.

Thing is, frequency and transmission power and EIRP must comply with what’s required in Japan and now I am working on confirming the requirements. I hope those Microhard pDDL and crossfire, which I didn’t know about, are acceptable.

In technical point of view, what does it mean by “that supports mavlink”? Maybe I don’t understand well.
Is what telemetry module does just to make UART line wireless? If that’s the case, what kind of wireless module does not support mavlink?

Yeah I am also thinking of that option.
Is that update frequency (every 30 sec) only for that RockBlock module? I don’t really know but I assume that those who use satellite communication for BVLOS would operate their UAV with higher update frequency…

Thank you, I’ll check them out.