COFDM bidirectional long range comunications for UAVs

Hello all,

I am studying the possibility of developing a unmanned vehicle communication system based in COFDM and LimeSDR seems the best platform to build this development. That i am trying to get is this:

System description:

  • One radio systems handling all UAV communications
    – Two or three video streams.
    – Telemetry (and mission control)
    – Manual control
  • Long range - 25km
  • Frequency 2.4Ghz

I made a small study of similar systems in the market. This long range COFDM technology has been military technology some years ago but now there are commercial products using it, for example DJI Phantom

This table shows some commercial and military products transmitting HD video in long range. My conclusion is that since commercial products that reach only 1km to military products reaching 240km all they have the same RF specifications (a sensibility about -99dBm), they simply change the frequencies and gains of the antennas.

My question is

How easy or difficult would be to develop a system like this?

I am starting to research about this project so any information about how to start or which way take to reach this goal is welcomed.

Best regards,


The LimeSDR has a receive and transmit limitation at 3.8GHz (3800 MHz) - so the Connex and COBHAM drones would be out for the time being. There is progress toward a frequency extension board for the LimeSDR that extends its useful range to (I think) 10GHz but that’s a little experimental right now - but it’s in the works.

All the other drones (Phantom 3, MIL, EnerLink) will work since they’re within the range of the LimeSDR bandwidth as-designed. In terms of the receive sensitivity, I don’t have numbers on it (possibly the Lime Microsystems team does) but the LimeSDR was developed to work within this range and with diversity - so it should be very possible to do what you’re thinking about.

I may add that you can develop the waveforms for these drones using GNU Radio Companion and the LimeSDR as a means to test what you have, then a specialized app can either be developed to navigate the drone, or reused with a LimeSDR driver to an existing app that’s been compiled to be compatible with the LimeSDR.

Good luck and hope this information helps -

Marty, KN0CK