hmmm... this new sparkfun board seems promising, boasting a 40 mi line of sight range and 3000m indoor range and it should be easy enough to connect to the APM. the data transfer is a little slower than the XBee pro at 115.2kbps but should extend the range to possibly farther than your batteries can take your UAV. this would be great for those using gas/glow for long missions. transmits on the popular 900mhz so bad news for those of you in eroupe. i did however send a message to sparkfun to see if they will make a version in 2.4ghz in the future. now to figure out how to break this guy out to USB so it will connect to the APM....
http://www.sparkfun.com/products/9411 Xtend 900 1W board
http://www.sparkfun.com/products/9596 break out board (no headders)
http://www.sparkfun.com/datasheets/BreakoutBoards/Xtend-Digi-Modem-V11.pdf Xtend 900 pin breakout
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I am curretly playing with these modems and have established communications using the sparkfun TTL to Serial board (at the PC end of the link only). I seem to be having trouble getting the APM board to change from 57600 to 9600. The full 40km range is achivable only at 9600 and the range drops as the over the air data rate increases. I get rock solid comms at 57600 but when I swap to 9600, I get no comms. The spark fun boards work perfectly. and they even do one with an RJ45 plug sold mounted... Stay tuned
i wonder how hard it would be to make the air dropable relay units solar charging (still have batteries) and self righting like the M93 mine. 6-8 spring loaded bars around the exterior so when it lands and senses it stopped moving they spring out so the unit is forced upright exposing say a 2W 9V solar cell like the one linked to charge a lipo cell and power it during the day. made out of a nice waterproof Fglass or kevlar composite for durability. i could see a small claw like deal on the UAV (copter/multicopter) so the UAV its self can pick up the units later. RF locator beacons are cheap so the uav could autonomously locate it and you could then manualy interface to pick it up. it would be cool but might take a bit of work and practice to get it practical. for now though you may have to retrieve the units yourself.
http://www.dinodirect.com/solar-panel-9v-2w-monocrystalline.html
These functional modules great, here is an example of its operation http://diydrones.com/profiles/blogs/summary-of-missions-in-auto-mod...
I looked into that about a year ago and really liked it! the problem was the price tag... 360 for two modules is really steep (for me - poor college student haha)
I have been working on an arduino mega shield for a similar radio, at less than half the price. RFM's DNT900. It too is a 900 MHz, 1watt transceiver. My board has servo connections, pressure/temp sensor, hook up for external gps, and video (2 sources can be video switched - and the output sent to your video transmitter!). Oh, and it can be controlled via a ps3 controller! much more light and comfortable than a big RC remote! I will get the 4 boards back from the prototype shop in about 2 weeks! If i can generate enough interest, I will produce a limit run and sell them here on the boards!
http://www.diydrones.com/forum/topics/new-long-range-telemetry-shie...
hmmm... maybe a RS458 to usb BOB from sparkfun, it has the RJ45 and a 3 pin 'screw terminal' nothing is attached so i plan to switch that terminal to a 3 pin headder. id have to make a PCB to make the Xtend's BOB have a RJ45 and 3 pin headder so it will connect with the RS458/USB BOB. there might be a need for a new driver though... their RS458/USB can handle 10mbs so it should be good with the Rx/Tx rate needed for controlling your drone. looking at the schematics for the Xtend's BOB it would be easy enough to make a RJ45+3-pin to a 11 pin headder (male) to connect with the Xtend and run a short cat5 and 3wire ribbon to the RS458/USB. it all should be able to fit within the footprint of the Xtend module its self so it wouldnt take up too much space (minus the cat5/3wire jumpers). i wont know untill i try but the Xtend is a little pricey... another project for another day.
http://www.sparkfun.com/products/9822
http://www.sparkfun.com/datasheets/BreakoutBoards/USB-to-RS485-Brea...