LED weather balloon of doom! / General Chatting / Forums

Forums

4hv.org :: Forums :: General Chatting

« Previous topic | Next topic »

LED weather balloon of doom!

1 2 next

Move Thread

LAN_403

Conundrum

Wed Feb 18 2009, 09:17PM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4061

Hi all.

Was just looking into sending back atmospheric data using a green Luxeon, from a helium balloon.

So far I've determined experimentally that a 5mm 5700mcd LED can be seen from over three miles (tested) and its likely
that the package can send back Morse data so anyone else seeing it can relay information back.

Also looked into keeping the balloon inflated using a metal/acid reaction generating hydrogen.

Comments?
-A

Nik

Wed Feb 18 2009, 11:08PM

Registered Member #53 Joined: Thu Feb 09 2006, 04:31AM
Location: Ontario, Canada
Posts: 638

When you tested the LED for distance did you have it pointed right at you? IF so then it may not be visible from all sides.

AND for retrieving data I have the perfect tracking solution: A pair of binoculars with your light sensor attached to one eyepiece. That way you know that as long as you can see the balloon/LED with one lens the other will also see it. (Credit this to Bill Beaty, he described this technique for finding non/human light sources with his Light-to-sound idea) Can be found here:

Chris Russell

Thu Feb 19 2009, 04:07PM

... not Russel!
Registered Member #1 Joined: Thu Jan 26 2006, 12:18AM
Location: Tempe, Arizona
Posts: 1052

I realize the novelty of the approach can be half the allure, but you really will see a much better range using radio as opposed to light, in the same sized package. VHF will get you line of sight, which can be a pretty impressive distance from a few miles up. The right HF band can get you global coverage. I think you're a lot more likely to come across people who are willing to switch on a radio and listen, than you are to find people who are willing to comb the night sky for a dimly blinking light.

Steve Conner

Thu Feb 19 2009, 04:34PM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

Well, this is the fundamental problem. High-intensity LEDs achieve their intensity by having a narrow beam, and if that beam isn't pointing right at you, it won't work. And if you use an omnidirectional light source, the range will take a hit.

It may still be usable with a telescope receiver. Markus Kuhn of Cambridge University has done some remarkable things with optical eavesdropping: for instance he claimed that some modems had the RS232 data in the front panel lights, and it could be read through a telescope, even reflected off a wall. His party trick is to reconstruct the image on a CRT monitor from the diffuse light that it gives off into the room. I wouldn't use an ATM within a two mile radius of the guy.

But radio is really so much easier.

Chris Russell

Thu Feb 19 2009, 05:15PM

... not Russel!
Registered Member #1 Joined: Thu Jan 26 2006, 12:18AM
Location: Tempe, Arizona
Posts: 1052

I've seen a single, vanilla, red LED work over a five mile distance on a clear day using scattering in the atmosphere. Both the receiver and the LED were pointed up, rather than being aimed at one another. The trick there was that the receiver was a photodiode with a 12" fresnel lens focused on it, and it used a long integration time -- it sent Morse at the speed of about 10 seconds per dit. It also used amplitude modulation of the LED, which is an absolute must in a case like that. That said, I still don't think it's a realistic solution, because of the specialized equipment and knowledge that would be required. Unless, that is, you're happy with the fact that you'll probably be the only one to track the balloon.

If the appeal of the visual method is that no special equipment is required, you could always set up a transmitter using more common frequencies. Nearly everyone has an AM or FM radio, and low power transmitting there is usually permitted with certain restrictions.

Conundrum

Thu Feb 19 2009, 07:34PM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4061

Interesting guys. Someone on #hvcomm kindly suggested multiple narrow angle LED's pointed in random directions so at least one beam is visible from the most common range of angles. If I was really clever I could have it turn off the most useless ones (near 45 degree angles) as it ascends to save power.

I also wondered about using a Luxeon Star LED pointing up illuminating the balloon itself (larger target, near 100% light usage) and also using a foam reflector to project as much light as possible downwards.

-A

Dr. Dark Current

Thu Feb 19 2009, 08:19PM

Registered Member #152 Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384

Well, the development of LEDs is going really fast now as well as prices going down, here you can get e.g a 15000mcd 80degree LED for about $1...

Proud Mary

Thu Feb 19 2009, 08:49PM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

You can buy a new, unused Microsonde GPS weather balloon unit for about $15.

Chris Russell

Fri Feb 20 2009, 03:56AM

... not Russel!
Registered Member #1 Joined: Thu Jan 26 2006, 12:18AM
Location: Tempe, Arizona
Posts: 1052

Harry wrote ...

You can buy a new, unused Microsonde GPS weather balloon unit for about $15.

Yes, but...

Actually, that's pretty neat. The chipset for the GPS alone would be nice to have.

Conundrum

Fri Feb 20 2009, 06:37PM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4061

I have two. Any use?

:)
-A

1 2 next

Moderator(s): Chris Russell, Noelle, Alex, Tesladownunder, Dave Marshall, Dave Billington, Bjørn, Steve Conner, Wolfram, Kizmo, Mads Barnkob