I would like to introduce you to a new radio modem that we developed for very long range datalinks!
Some of the key features of the RFD900 are as follows:
These modems are designed to support long range applications, while being easy to use and affordable.
These modems have been flying in various platforms and have demonstrated excellent performance in real applications.
RFD900 modems are now available at: http://store.rfdesign.com.au
Support within APM planner and the radio configurator from Michael Oborne is already available.
It works seamlessly with APM planner, all radio Mavlink parameters are available.
Update, December 2014: The RFD900+ with improved specifications is available now at:
Can the rfd900+ take an sbus signal and send it to an rfd900u, which will then output that same sbus signal?
I am also curious about powering the RFD900 externally or from the flight controller. It would be simpler to power the radio from the flight controller, so this is my preferred solution. Is it not recommended to do so because you risk to damage your flight controller by drawing too much current, or because the telemetry range could suffer because the radio cannot get enough power? Other outcomes? If it is a question of the range being restricted, I guess it is a matter of testing to see if the actual range you achieve is sufficient for your use?
Thanks for sharing any insight on this
I'm looking to put the antennas for my 900+ (for uav basestation) and 900x (for remote instrument control) up on a pole (up to 60' if possible). Can I use SMA extensions to connect the RFD radios on the ground to their dipole antennas on top of the pole? How far can antennas be extended without interfering with performance? Is there a better way to do this?
I'd think you would want to mount the modem on top of the pole and run data & power over the 60 feet (using a $30 active USB extension) rather than the coax because losses can be quite high. Try this calculator - http://www.qsl.net/co8tw/Coax_Calculator.htm It shows 9.2dB loss even with a 1:1 SWR with RG-58. Of course, you could look into low-loss coax but I'm guessing that may get pretty pricey for 60 feet. Not sure. Interesting project. Good luck.
Thanks for the suggestions. I think I'll try to find someone who can make an active USB extension out of silicone wire or something so it's not going to break in sub zero temperatures. I suppose this should also have some kind of shielding to?
Well, USB needs one twisted pair for each direction. If you can't find an off-the-shelf outdoor type, maybe you could buy the indoor type and just use the electronics by replacing the cable with two silicone twisted pairs. I do see an indoor one (SKU #1501-SF-52 at sfcable.com). The active electronics module is only on one end and it looks like that would be the end that plugs into your pc so it would be indoors (I assume) and wouldn't need to be outside where it might need to be heated. Well lots of stuff to think about and experiment with. Sounds like fun.
If you were really going to go the home-made USB cable route, CAT-5e would be a good choice. Here's some rated to -40C. Not sure about price but probably fairly cheap: