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Permalink Reply by Jake Stew on May 28, 2012 at 10:45pm

The wifi isn't going to work IMHO.  There's lots of interference.  It also takes a few secs (long enough for your drone to crash) to connect and it will frequently be switching APs.  Both cell phone and wifi antennas are usually panel/sectional antennas mounted high and pointed at a downward angle towards the ground.  So you will have a lot less range than you think by being in the air above them.

I'm not aware of a commercial system that will give you the range you want.  If there was one it would draw way too much power to be useful.

The system I'm working on is a 4W ATV band transmitter, which will probably give that range fairly easily with good antennas.  But that's a ways off from being finished and will draw too much power for most applications.  I figure a fixed wing with a gas motor will be all it's good for.

Some people are using wifi for video with their own APs with good antennas and/or antenna trackers.  But all the simple, commercial ready-to-go systems I'm aware of are good for a few thousand meters at best.

I'd suggest getting the most powerful video transmitter you can at the lowest frequency you can use in your area.  Then use a good directional antenna mounted high on some sort of mast, possibly attached to your vehicle.  On the aircraft side I've seen some youtube vids with antenna tracker systems using directional antennas mounted on the plane.  That's the only way you're going to get the range you're asking for IMHO.

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Permalink Reply by Shane Anderson on May 29, 2012 at 5:46am

I've already decided on it being gas powered, I haven't decided yet if I should just have several large capacity batteries or a single battery with an alternator or generator on board, depends on power requirements.

What I'm curious about is if I get say a 10mw xbee module, can I simply boost it's power to get more range? Say crank it up to 1-4 watts?

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Permalink Reply by Jake Stew on May 29, 2012 at 8:20am

Xbees are on the way out.  They've always been a crappy solution.  If you want 100mw try the 3DR/HopeRF Si1000 based radios.  They've got a lot more power, better receive sensitivity, faster data rate, and are cheaper.  I feel sorry for anyone who accidentally buys a Xbee nowadays.

If you want 1W (the max legal limit without a license) wait for the RFD900 talked about in this thread... http://diydrones.com/forum/topics/rfd900-new-long-range-radio-modem

It uses the same Si100X chips and firmware as the 3DR radio, but also has antenna diversity, extra pins for controlling things, and a nice little integrated amp to bring it up to 1W.  With the right antennas you should get easily 40km+ running at 1W.  It's THE best solution out there by far.

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Permalink Reply by Jake Stew on May 29, 2012 at 8:23am

You may also want to check out this thread... http://diydrones.com/forum/topics/gas-engine-quad-ideas-and-solutions

We discuss gas engines, electronic ignitions, and alternators/generators.  Not much definitive information, but good discussion and ideas.

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