Discussions

Can anyone suggest a good path for 5.8GHz tx/rx for UAV telemetry?

Posted by Brett Glossop on May 30, 2010 at 8:01pm

Hi everyone,

Is there a good path to 5.8GHz UAV telemetry or a commercial combo?

I'm in Australia so 900MHz is illegal.

The only 5.8 GHz combos I've found being from blip and they are about 3 x as pricey as the Xbee 2.4 GHz telemetry from DiyDrones.

I'm just starting out in this UAV game (AP only so far) so I'd prefer to start on the quality but lower end till I know what quality I need etc.

FYI: I use a Spektrum 2.4 GHz set for the plane. I have some electronics skills (soldering, rewiring, building from kits) but not redesign skills (latter probably illegit anyways and I want to 'play safe' with the laws).

thanks in advance,

Brett

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Replies

Steve Croft July 12, 2010 at 1:25am

I've rigged up a 5.8GHz downlink for a UAV company, using Airwave TX/RX's. The TX was only 25mW, a night test resulted in 500 metres range with clear video, a small pcb 7db patch was used on the RX.

Checkout Iftron online,http://www.iftrontech.com/5.8GHz-Diversity-Pro-Receivers/c48/index.... they make a 5.8GHz diversity Pro receiver, this produces very good results.
Matching TX's range from 25mW to 500mW.

The 2.4GHz band is a bit too busy for my liking for a reliable downink. 900Mhz & 1.2GHz band are better, but, illegal in many countries.

Steve
John Holdsworth June 1, 2010 at 7:33am

if you want to go 5.8 (against the advice here) then try BEVRC (birds eye view) web site...

www.bevrc.com
Brett Glossop May 31, 2010 at 9:08pm

Thanks for all the replies, much appreciated.

I just found out that the Xbee rf tx would be a no go (unless modified) due to it overlapping with GSM mobile phone network.

From ACMA in Aus:
Please note: the Australian 900 MHz ISM band is strictly limited to 915 MHz – 928 MHz. Australian mobile telephone carriers operate their GSM mobile telephone networks between 890 MHz and 915 MHz so operating at or below 915 MHz will almost certainly interfere with these services. Severe criminal and civil penalties exist for interfering with licensed services.

From Xbee datasheet:
Frequency band: 902 - 928 MHz
and no C-tick (Aus certification)

Maybe someone here knows how to modify????
Ryan May 31, 2010 at 3:03am

Keeping them far apart isn't going to do anything for you!

I mean, think about it, if you keep them 12" away and hope to that the signal will be weak enought to not interfere then how do you expect it to reach the ground where you're standing :)
Fouad May 31, 2010 at 12:34am

I had bad experience in this subject using similar combination, here is a reference to my previous thread:
http://diydrones.com/forum/topics/score-xbee-pro-2-receivers
Ryan May 30, 2010 at 10:45pm

Using 2.4ghz for telemetry in conjunction with 2.4ghz RC gears you will experience some link quality degradation (spelling)
especially if you use high power telemetry link.

I you must use it then I suggest using Futaba FASST instead of JR/Spektrum because Futaba FASST does true freq. hopping and so will your 2.4ghz telemetry link thus they will less likely to step on each other.

I however know that Futaba gears/services in Australian is sh*t - nobody seem to carry them in the shops which is unfortunate but Toy Trader (the importer) is not doing a very good job.
3D Robotics

Chris Anderson May 30, 2010 at 8:25pm

I would avoid 5.8. The higher the frequency, the worse the range in my experience. You can use 2.4 even if you're using 2.4 RC, however.