Bidirectional Video & Data Transmission from an Airplane? 9
airjose asks: "I 'work' (if you can call it that) for Skydive DeLand in Florida. We have a Hi-8 camcorder shooting exit images, and I would like to transmit them to the ground. I can get 2.4 GHz video transmitters for $1200 (we are flying the plane at 13,500 feet) but I'm hoping to get two way video and data services. Is this would be too expensive, or are there cheaper solutions?"
hey someone died there today. (Score:1)
Interesting that this got posted today (Score:2)
<A HREF="http://www.canoe.ca/CNEWSTopNews/sky_apr14-
Against FAA regulations isn't it? (Score:2)
Low tech answer. (Score:1)
It'll be on the ground ready to play well before the jumper arrives.
-Peter
$1200 Too Much? (Score:1)
It's not that much money to spend if you want the technology. A new computer will probably run you more, heck the camcorder you bought was probably half that.
If your in financial straights and can't afford $1200 perhaps your focus should be else where now, and not on the technology to beam images to the ground.
Change your focus, then once you have a few thousand in your capital expenditures budget, use something that is designed for the task you are trying, and don't try to cheap out. From the sounds of it though (see previous article)
Makes you wonder where else they are cutting corners doesn't it.
You are joking? Right? (Score:2)
Is this 2.4 GHz kit approved for aircraft use? If so then you have found a bargain. Does the $1200 include the cost of installing it? Where does the antenna go?
However, I have a horrible suspicion that you think that you can just take a commercial 2.4 GHz video transmitter and "put it on an aircraft". Have you any idea how much it would cost to get FAA approval for this (assuming they would allow it at all)? If we were talking a light aircraft with just you and your buddy on board then you might get away with it (or at least avoid a prison sentence if caught). But you are proposing to do it with fare paying passengers!!
Your biggest problem (well one of them) is going to be the antenna. Where are you going to put it, remembering that it needs to basically point down? If you fix it to the outside of the aircraft then that is an external modification which requires the approval of the design authority (usualy the plane's manufacturer). You need to prove to the FAA that it won't effect the aerodynamics. Obviously a small antenna won't but you need a official letter saying so and they cost a lots of money (thousands). You might be able to come up with some scheme involving a small patch which you can push out through the door (maybe!). If we weren't a government agency we could design such an installation for you. It wouldn't cost less than $4000. And as for the loony in another post who suggested fixing it on with sticky tape, well words fail me! What happens when it comes loose and the cable wraps itself round the tail? Well, at least some of those on board will have parachutes!!
Next, if the 2.4 GHz transmitter isn't type approved for flight use then you need it tested for EMC. Its not enough to say "nothing else on the aircraft uses 2.4 GHz". How do you KNOW that it doesn't produce some small spurious signals on a frequency which you do use? Again, this is going to cost thousands.
Remember, you can get away with quite a lot on small private aircraft and those with special experimental licenses (by which you can become your own design authority), but once you start carrying the paying public the rules get much tougher!!
Hopefully the two-way video isn't for the jumpers (Score:2)
1. Your insurance company would probably appreciate it if you checked all the avionics for interference while this stuff is turned on and functioning. While I cannot think of anything in a normal aircraft that would have hassles with 2.4 Gig, one never knows.
2. If you are in a fairly rural setting, you could try just about any vendors 802.11b equipment and laptop PCs. Use external antenna with reflectors to get as much power as possible into the area that the plane will be in. Remember that most omni antenna are designed to produce a toroidal volume (normally you want the power concentrated in a circular plane near the ground) so you may have to use a custom antenna here.
3. Use laptop PCs as before, but use multiple cell phone channels to get your signal back. Use software to distribute packets among the six to eight channels you are going to need. ;)
4. AMSAT or InMarSat M can be had for aircraft. Expensive, but gets you 64K both way over most of the US. Use laptops as before.
If you are really geeky and have the know-how, and you can adequately predict where the plane is going to be, you might want to consider 802.11b with narrow beam antenna and active tracking. The plane might have to hold on station for a few minutes whilst comms links lock up alignment and tracking. The best way to do this is by having a search program divide the look area into quarters, measure signal strengths, take strongest quarter, divide again, measure signal, repeat until adequate.
hmm... (Score:1)
Just make sure your on Different Channels, and it should work fine.
Two-way video? Why? Go the cheap route. (Score:1)
If you are considering this, you probably know that obeying the KISS principle is the way to get things to work. Here's my take on it:
- Forget 2-way video and data. You need two-way voice and a video downlink, and you probably have the voice already.
- If all you need is a video downlink, put the complexity on the ground. A 2.4 GHz transmitter is a piece of cake to find; put the antenna on the bottom of the aircraft with double-sided tape or something. Power it with aircraft power if you can, but batteries will probably do just fine.
- On the ground you need an antenna, receiver and video gear. Take your cheapo receiver and put its antenna at the focus of a 3 or 4 foot parabolic dish on an az-el mount. Have someone track the plane with the dish while you are doing video (only a few minutes per flight, I'd assume). As soon as the last jumper is out of camera range, you're done and your plane-tracker can lock the dish and go do other things.
Motorized dish controls would be nice, but a small dish is fairly easy to move using the Armstrong method as long as it's balanced. Remember, you are after cheap and reliable. Once it starts making a lot of money you can think about making it fancy. Note: You could probably use the same dish to capture video from a jumper's helmet camera, even using the same dish. You would just want some way of switching between cameras as that jumper left the aircraft.--
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