Affordable, Homebrewed Optical Networking?

Graham Wheeler asks: "Lately I've been obscessed with grassroots community network projects, and the hardware that enables them. Most sites I have seen focus on wireless RF networking, but I have noticed a few projects revolving around free space optical transcievers. Twibright Labs' RONJA is a good example of what I'm talking about. Not being an electronics hobbyist, however, makes the various plans for building a comm laser from scratch look rather daunting. It seems to me that it would be easier to just make a lens and housing system into which would go one of the many cheaply available copper-to-fiber media converters. Then you could simply modify it so that the laser ports were optically connected to the TX and RX lens assemblies instead of the standard fiber interface. So, what factor(s) am I overlooking that would explain why nobody seems to be doing this?"

Comments

My company does this

[MrResistor]

...for agricultural telemetry and irrigation control. What we use is lower bandwidth than what you want (RS485 over ifrared), but the basic principals are similar.

The biggest problem we have is reflection. A unit sending data gets back a reflection of that data off the receiving lense. If you're just using 2 stations, it's not that big of a problem to scan the buffers for reflections, but we've found that with several units (usually all communicating with a central base-station) collision becomes a serious issue, and detecting/masking reflections is extremely difficult.

Hope this helps. Good luck on your project.