Laser Communication

[alaskalonewolf]

How reliable is point to point DATA communication using laser technology? Is there any off the shelf gear anyone has used with any success?

[mlarma]

That's kind of an open question. Through a vacuum, very reliable (provided your aim is right on). Through air...well, depends. Since the atmosphere has water vapor and other stuff, your signal will drop with distance as some light is diffracted or absorbed by the foreign material. That's speaking off the shelf. The thing is that Heathkit back in the late 80s had a HeNe laser that my 14 year old self wanted...bad. (but $300 in 1987 is a buttload of dough) Anyway, it had the laser AND a receiver, so you could modulate the beam to carry voice. Since that was in the analog domain with amplitude modulation, the same would be true for data, but you're looking at setting a clock on each end and/or putting in an error correcting protocol around the data. So... I would suggest looking at a site/catalog like Black Box (the network guys) and see if you can get any ideas. Again, anything is possible...just depends on what you want to spend. Have you thought about doing something other than laser, like microwave or just kicking 802.11 up a few watts with a parabolic dish antenna at each end? Just a thought....

Mark

[alaskalonewolf]

I would very much like to lay my paws on that gear. Do you still have the technical data, like the focal length, the wavelength, etc... it is a visible light or IR? I've been searching for it for a while now. Line-of-sight like that has some rather nice properties, like for example you know when someone's listening since they would only intercept by breaking the beam. Plus, you can go around corners with the right mirrors... or reflective surface. Been doing a bit of reading, but I'll admit I got more out of your post than an hour in Goooooogle. (Yeah like six o's)

[alaskalonewolf]

Probably I'd lay out around two large for the laser if it has the snort... like .8 mW to 1 watt. If I can find one. That $300-400 kit sounds kick ass, a damn good start, for me anyways. I'd spend another grand for the A/D conv. and software if they even make any. Been having a helluva time finding decent shareware for some reason. Maybe it's jus' me. There's a lot of garbage on the 'net it seems.