Build Your Own 10Mbit/sec Optical Data Link

redcliffe writes: "This website has complete plans to build a 10 megabit per second optical data link that can work over up to 1 kilometre. It uses fairly cheap components, such as standard LED's instead of laser diodes. This also makes it a lot safer to work with, i.e. you won't burn your eyes out if you accidently look into it."

Comments

Why not 802.11b?

[msolnik]

The equiptment is cheaper easier to make/get and can get further range. I can get upto 15 miles in Houston with 2 15db direction antennas that you can get for 40$ a peice.

Re:Why not 802.11b?

[laserjet]

You have a good point, and 802.11b probably would make sense in most conditions. The only benefits that this would offer you are 1) if you work in an area that has too much RF interference for 802.11b to work correctly, and 2) this would be more secure that 802.11b. For instance if you want to run a connection to your neighbor across the street, to intercept your connection, someone would have to get exactly in line with the transceiver, whereas 802.11b is broadcast all over the place.

Aside from that, it just looks like they built it because they could, and that, is reason enough.

Re:Sigh...

[Anonymous Coward]

Having said that, those few mW are very consentrated compared to say 70W lightbulb.

Uses the AUI interface

[Animats]

This works because the AUI interface is still around. That's the original, really simple, interface used with the original Xerox PARC Ethernet tranceivers in the 1970s. It still works.

Others have done similar things with the AUI interface. Here's an RF link using the same technology.

If you want more range from the optical link, I'd suggest putting an optical interference filter (from Edmund Scientific) in front of the receiver. Pick one that matches the color of the transmitted beam, and you'll reject most other light.

Use these for backbone of (community) wireless?

[Brian Stretch]

These, or higher-speed commercial point-to-point transmitters, seem like a neat way to set up a wireless backbone for a (community) wireless network. Then you just hang WiFi transmitters off the backbone access points. Actually, I'd want something a bit faster than 10Mbps for a backbone (aggregate multiple transmitters?), but you get the idea. I'm not sure it'd be superior to using the new 802.11a 5GHz gear for such a backbone, but in either case, you avoid dealing with the local telco monopoly, which is always a Good Thing.

Maybe put small caching proxy servers at the access points backed up by a big one at the end of the network? Or just the latter. If you're liable to wind up with a Linux box at the access points anyhow...

I've already got a cable modem and I'm lazy, so I'll let someone else run with this :-).

Fiberless Optical Networks

[Alien54]

There was this old story about a company doing something similar with lasers between skyscapers, etc. I suppose the usual fog and bird problems apply. And maybe some mean spirited neighborhood kids with a couple of balloons

Personally, I wouldn't mind a way to do this sort of thing by shortwave. It would be great for WAN applications between cities [shrug]

Re:Not to mention reliability...

[markov_chain]

What are you talking about? The guy built 10 Mbps transceiver out of some LEDs-- a far cry from 10 Gbps. He used ordinary Ethernet NICs with AUI ports and converted the signal into light. Replacing the LEDs with laser diodes should be easy .