Is 2.4Ghz good for an UAV?

Question

I'm designing a drone(UAV) as a hobbyist, and radio communications is not my strong point. I will be transmitting waypoints from a portable control station and receiving video(a low frame rate is ok). I'm trying to decide what frequency I should use. I want to get a range of about 1 - 2 miles with not a lot of power. Are there power to range benefits from using different frequencies? At the moment I'm thinking about using 2.4Ghz is this suitable for my needs? Thanks!

Answer 1

The frequency you choose is largely irrelevant with respect to range, at least within the range of frequencies you are likely to choose for this kind of application.

Size limitations (and probably licensing requirements) will probably dictate VHF or UHF, and so you will be using line-of-sight propagation. Regardless what frequency you select, electromagnetic radiation is subject to the same inverse square law. That is, in the absence of obstructions, 2.4 GHz radiation "travels just as far" as that of any other frequency you might reasonably choose for radio communication.

See:

• What is a link budget, and how do I make one?
• Is free space path loss dependent on frequency?
• What does the Friis transmission equation represent and how is it derived?

Answer 2

If you mean 2.4Ghz for video, how are you going to control the R/C model? 2.4Ghz spread spectrum is the most common R/C control link. A 2.4Ghz video transmitter would probably swamp your R/C control RX.

I've done a 3.5mi flight with 2.4Ghz control and 5.8Ghz video. That was a 200mW video transmitter, and a "pepperbox" antenna. It's very directional. It has a 160deg beam width, but 60deg beam height. I was also out in the middle of nowhere where the noise floor was really low (and I wouldn't damage anything if I crashed and I knew I could retrieve if I crashed). The flight was pretty much straight and flat. I say all this to say that the environment and antennas matters a lot.

In general you'll have better luck with video on lower frequencies. 900Mhz is about the lowest I have seen folks use for video, antennas get pretty big though. It might be hard to find ready-made gear for anything else. I have seen some compact 1.3Ghz antennas.

Answer 3

You might be looking for wifibroadcast, a form of low latency digital video broadcasting (motivated by controls of R/C models...)

Prominent features:

• uses Raspberry pi
• uses raw wifi frames, thus does not need association between the receiver and the transmitter
• video is received as long as the receiver is in range, with increasing number of errors as the signal drops (but the connection does not drop sicne there is no connection)
• low latency
• kilometer(s) range is achievable in good conditions
• diversity (reception with two different antennas) can improve reception under low signal/noise/reflections conditions
• unfortunately, wifi hardware does not pass frames with errors, which makes the reception less ideal (lower range) than it could be