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skola28

802.11__ (fill in the blank)

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This is an open discussion of an idea I had on alternate methods of FPV, UAV, etc.

I have two ideas, first off:

Using 802.11a/b/g/n or any other method such as WiMAX, UWB, to transmit data to the aircraft. With all the wireless networking options going around these days, it seems that incorporating a small computer onboard an aircraft, and equipping the computer with some flavor of Wifi could be extremely beneficial... I know it is possible to tranmit data over quite large distances with Wifi. Most versions utilize the 2.4GHz frequency (not counting 802.11a which is 5GHz). Major benefits would be massive amounts of flexibility with software and modifications onboard the aircraft. Getting GPS data, telemetry, etc would be highly simplified.

Secondly, why not use a SpringPCS card or similar cellphone/mobile-phone based card on the PC installed in the aircraft? This would have EXTREME range possibilities as long as you don't fly to high, or use Sprint :P .

Just a thought, and wanted to see what some of the veterans think :)

(Kilrah, vrflyer, I'm looking at you two).

J. R. Skola

Cedar Rapids, IA

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The main problem from my point of view is range. Yes, with Wi-fi you can extend range using directional antennas. But the first point is that it won't be legal in many places as you would exceed the maximum EIRP.

Another thing is that Wi-Fi's modulation, encoding etc haven't really been designed for range but more for high speed at short distances. It's supposed to change speed as signal weakens to reduce errors, but from what I've seen in practice it doesn't work so well. Usually, nothing will pass through the connection anymore before it has had the chance of doing anything...

The GSM-based approach would be better IMO, but being aware that the throughput isn't very high. Connection reliability is to be taken account of as well.

Anyway, considering this sort of stuff is already getting into very serious UAVs. For now, I've promised myself not to go further than I do now until I've made an autopilot that would be able to cope with any link problem that could happen.

Heck, 1.8km with 10mW is already enough for many things...

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1.8km with 10mW is already enough for many things...

Wow! :blink: I'd say you've got that system tweaked... lol Care to point me to more details on it, like antennas used?

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Well.. the TX antenna looks like this:

P1230797_t.jpg

and that 1.8km flight was done using a 30dB gain RX setup (14dBi panel + 16dB preamp).

But I usually fly with a simple 8dBi patch on the RX. Standard range is 1km, in good conditions I've gone up to 1.2km. I don't have a guy to spot the plane, I just align it in the direction I intend to fly towards before the flight.

Actually why I don't want to go further is mainly the R/C range, which is generally blocking me at random distances... On the 1.8km flight the video was still very good, I could have gone further if that plane hadn't started jumping around a bit too much...

Edited by Kilrah

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Cool. I love that setup, the video was great! Not to get too far off topic, but where might I find more info on the preamp?

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Thanks ;)

It's a panel antenna with built-in preamp. It was made by Hyperlinktech but it's been discontinued for about 1 year now :(

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I'm currently experimenting with some RF Modems from sparkfun, 9600bps to 1.5km (supposedly). Kind of expensive though at $90 a piece, and you need 2.

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Somebody used a hardware router running linux to control a rc car

http://yasha.okshtein.net/wrt54g/index.html

So, one can't claim it is impossible, but ....

* consider the weight

* a computer

* ram

* storage

* cpu

* power

* consider the points of failure

* the wlan itself, wlan is nothing i'd call 'robust' or 'reliable'

* the software

* operating system

* anything used to control

* latency

using gsm or umts data services is no real alternative too

I think sticking with what works now and looking what comes next is best thing one can do currently.

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Sweet... That WIFI car project looks promising and I can assure you I'll be following it. I bought a $5 router (just like the one he has) from www.fon.com. I think I may 'toy' around with the same thing.

Kilrah, are you saying you're working on an Autopilot of sorts? On the aircraft I built in college last year for my senior design, we had a very simple method of 'autopilot'. We found a trainer R/C aircraft online which had a module that sensed heat/cold of the sky/ground. When we lost connection (or flipped a switch) the module would auto-correct the attitude of the aircraft to fly level plus a slight left rudder input (so it would circle). This actually ended up working pretty well;we had planned on further implementing some GPS waypoint following, but ran out of time.

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Yep. My final engineering school project is a telemetry/autopilot system. Basically very complete avionics, able to recreate all the cockpit instruments of a full-size aircraft live on the ground. The autopilot is mainly there for safety measures, technical challenge and openings to some "real world" applications. I personally prefer flying myself, that's where the fun is :)

As opposed to many school projects that I've seen, all the airframe/flying part is already OK for me, so I'm just concentrating on electronics... and the project-related paperwork (sigh).

I now have 3 months of (supposedly) full-time work on that one. Something with the recent happenings tells me that this will rip a bit though. The nights are too short :(

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Kilrah, your project is fascinating to me! I really hope you will post further details and videos of how it all turns out. I plan on getting UNAV's Pico Pilot and putting it on my Slow Stick, but thats still down the road a bit.

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