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-... Xtend 900 pin breakout
I should be getting a few prototypes by next tues - I'll let you know how they work! They could be easily adapted to simply act as the repeater beacon you are looking for. Keep us updated how your boards turn out!
(are you using the laserprinter method?)
yep, laser printer. and sodium bisulfate/peroxide as the etchant. a little quicker and not as toxic as iron chloride. you can get sodium bisulfate cheap in Kg ammounts as ph buffer for swiming pools.
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
Oh and on another note!!!!
If you are in Australia you MUST flash the modems with the Australian firmware before you use them. The firmware changes the hopping frequencies used by the modem to stay out of the optus mobile telephone network! You have been warned! You will need to do this using the Sparkfun TTL to serial port adapter. Plug the modem via the board into a serial port on your PC, run the X-CTU software which you can download from the Digi website and upload (flash) the Australian firmware (#2268) to the modem. The standard baud rate for initial communication is 9600bps.