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....  Xtend 900 1W board break out board (no headders) Xtend 900 pin breakout


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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.

this might work to take the Xtend board to RJ45 and 3 pin. just need some 2 sided blank PCB a 12 pin female headder ( one blank pin)  a 3 pin male strip and a cat5 (RJ45) socket.


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!

i like that!  i like the Xtend but your DNT900 has a much faster kbps rate than the Xtend andmore than the Xbee for that matter. i would be very interested in one of your sheilds as well if they work out. count me in for one! i could see using the DNT900 as a dropable midpoint relay station to double that range. i am working on a mini CPU based on the beagleboard that could use the DNT900 to stream relayed commands via RF as a secondary ground station. im trying to squeeze it into a small water proofed package so it can be dropped at a half way point and picked up on the trip back or later on.

These functional modules great, here is an example of its operation

I really like the idea of a midpoint to range extend...  to air drop repeater stations when you are flying long range!


One of the fantastic things about these boards is they can work in a wireless mesh topology. You could effectively scatter a handful of these throughout the area, and they will bounce the signal around by themselves


If you want more info on the raw capabilities of the DNT900 radio, check out RFM's product manual   < these are really quite remarkable!

These are excellent units. I fly with them for about a year at a distance of up to 40 kilometers without any problems.

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.

Hi, Alex  Do you use XTend 900 without any problem ?? what is the accessories for example the Anttenas to get 40 kilometers ?? if u have any pictures that will be very helpful..... thanks in advance

printing out and etching a couple proto boards tomarrow... still gotta get an xtend to try it out with, the DNT900 is looking better though just because of its stand alone capabilities and nice kbps rate.

without any problem =)


Ground Yagi 11dBi

UAV -  antenna from a kit


P.s. With  antenna from a kit on ground I flying at a distance 15 km.

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?)

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