Building A Long Range UAV
I am working on a project of controlling a UAV over long ranges, for example would it be possible to control a UAV Via wifi?. 2.4ghz has a range of 140 mile with the proper equipment, so would it be possible to operate a UAV within this hotspot?. Once I figure out the range issue the next step would be to figure out how to control this UAV via Windows PC with joystick and throttle. I really think this can be done with the technology we have available to use, but I am new to the R/C scene and I may be wrong.
Replies to This Discussion
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Permalink Reply by Krzysztof Bosak on -
"2.4ghz has a range of 140 mile with the proper equipment"
With this equipment you can also fry chickens.
Search for LRS systems, like Scherrer LRS. It's all done.
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Permalink Reply by Ken on -
"With this equipment you can also fry chickens."
LOL. I was going to say you could pop corn. :)
But, you could do it with ~1 watt if you were willing to use 10 to 12 foot dishes at each end and did it in desert dry air. It would be a heck of a UAV that could carry a 12 foot steerable dish...
It would still be illegal, at least in the US, no? I've forgotten the formula, but starting at 1 watt don't you have to cut back power 1dB for every 3dB of antenna gain or something like that. Bet Earl would know...
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Permalink Reply by Dean Franks on -
Don't confuse EIRP with actual power. You cannot cook a chicken with one watt regardless of antenna gain. The beam would have to be focused on a very small spot on the chicken to produce significant heating. With a dish the beam is never that focused, it just diverges less over distance (narrower beam width) giving the appearance of higher transmit power at long range.
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Permalink Reply by Ken on
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I was not confused.
After the joke I mentioned *another* way of achieving the range *without* using huge power.
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Permalink Reply by Ken on
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Found it. Yes, for unlicensed operation, if you use a directional antenna you have to reduce 1dB for each 3dB.
Permissible under Part 15: Max. Transmitter RF power Ant. gain (dBi) EIRP (W)
2.4 GHz omni-directional 30 dBm (1 W) 6 3.98
2.4 GHz directional...........29 dBm (800 mW) 9 6.35
......................................28 dBm (640 mW) 12 10.14
......................................27 dBM (500 mW) 15 15.81
......................................26 dBm (400 mW) 18 25.23
......................................25 dBm (320 mW) 21 40.28
......................................24 dBm (250 mW) 24 62.79
......................................23 dBm (200 mW) 27 100.2
......................................22 dBm (160 mW) 30 160.0
As others have said, if you get an amateur license you can up the power to "chicken roaster."
Achievable under Part 97: Max. PEP RF power .........Sample Ant. gain...........sample EIRP (not a limit)
2.4 GHz (SS i.e. 802.11 or 802.11b) 1 W w/o using APC (per 97.313) 24 dBi partial parabolic 252.2 W
2.4 GHz (SS i.e. 802.11 or 802.11b) 100 W using APC (per 97.313) 24 dBi partial parabolic 25.1 KW
2.4 GHz (non SS i.e. 802.11g) 1500 W (per 97.313) 24 dBi partial parabolic 376.8 KW
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Permalink Reply by Gary Mortimer on
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Just for interest, how high would the UAV have to be to still be in radio LOS at 140 miles??
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Permalink Reply by Ken on
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If the base station was at 10 feet, the UAV would need to be above 10,000 feet.
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Permalink Reply by Bertrand Duchiron on -
You can use the Iridium sat phone system, it is use by the US force to control the Global Hawk UAVs over the Arctic region.
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Permalink Reply by Dean Franks on
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Two possibilities:
Get a 3g cellular aircard (e.g. Verizon EvDO) and do everything over IP or get a Technician Amateur radio license (assuming you are in the US).
The power for a remote control link under amateur radio rules is limited to 1W (no limit on antenna gain and you have lots of frequencies to choose from). I believe that you could get away with putting a fast scan video transmitter on the UAV and then using the telecommand rules (97.213) to implement a control link between your "control station" and the UAV.
In all cases you are going to have to do a data link rather than pwm/ppm for control.
Both these solutions are going to require a significant amount of engineering, if you are new to the RC scene then start with a standard short range RC system, learn to fly, modify the airframe to use a data link/autopilot, only then start thinking about long range operation.
Be aware that there are new rules in process that will place restrictions on the operation of UAVS at long range, and there are already lots of restrictions relating to airspace rules (and lots of federal employees with no sense of humor about airspace incursions).
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Flight Level or Altitude Radio Line of Sight in Nautical Miles
15,000' 150.6
14,000' 145.5
13,000' 140.2
12,000' 134.7
11,000' 129.0
10,000' 123.0
9,000' 116.7
8,000' 110.0
7,000' 102.9
6,000' 95.3
5,000' 87.0
4,000' 77.8
3,000' 67.4
2,000' 55.0
1,500' 47.6
1,000' 38.9
I knew I had seen that somewhere ;-)
You could of course just fly from free Wifi hotspot to free wifi hotspot, in fact if you flew from a coffee house you could drink coffee at your command centre.
http://en.wikipedia.org/wiki/Radio_propagation
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Permalink Reply by Krzysztof Bosak on
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You can expect some 20km from 800MHz region modems and 9600baud.
There is whole rcgroups discussion on that.
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