XBee Pro or Xtend Data Modems?

[jtprouty]

Hi All,

I'm trying to decide which data modem to use with my autopilot and can't make up my mind. I have experience with Digi's Xtend data modems and like them but I'm leaning towards using the XBee Pro 100 mw modems on my next project since I won't be flying more a mile from my base station (going to chase and keep the plane in visual range.) Has anyone out used the XBee Pro? My biggest concern is if it would have sufficient throughput to be able to send commands from a ground station and still send information back to the ground.

Thanks in advance for any information.

Jimmy
KD0DOI

[Mark Hanson]

I'm trying to decide which data modem to use with my autopilot ....
KD0DOI

When it comes to radio modems, my rule of thumb is "use the lowest power
you need". RFI (radio frequency interference) can cause major problems on UAVs and even threaten flight safety. The XTend ( 1 W ) may seem useful with a range of 40 miles ( directional antenna ) but we've had several reports of RFI problems with it. I like to use the 1 mile range XBeePro ( wire antennas ) which is adaquate for most close-in missions. I've haven't had an RFI problem with the XBeePro yet (knock on wood).

[jtprouty]

Thanks for the input, Mark.

Do you use two-way communication from your ground station to the UAV? Have you had any problems with throughput?

Thanks again,

Jimmy

[eddymoore]

Good antenna installations make all the difference. Filtered connectors into your avionics box and emi filters on ADC lines and those kinds of sundries make a big difference. 1W is tonnes of power. On our high altitude balloons we can get lat/long/alt and other gubbins (about 80 characters total) from a shade over 500km (if it's got that far away, it's gone wrong) with a 10mW radio. Admittedly it's only 300 baud, but it's enough for the essential info. That doesn't help you specifically, but I always like to think of things like that when I think I need 'more power', be it in an avionics cpu (scout rocket reached orbit reliably with a paper tape flight computer) or a radio or whatever.

[Jack Crossfire]

Sparkfun started selling 4800bps 315Mhz radio modems. They're cheap enough to build a full duplex system for 1/2 the cost of using XBee's & they won't interfere with video. It's only 500ft unfortunately. Stay out of 2.4Ghz to avoid paying big bucks for video.


http://www.sparkfun.com/commerce/product_info.php?products_id=8945