Laser Data Link

[planters]

I am looking for a commercial solution or at least a starting point to construct a high speed, long distance free space laser data connection. Ideally, it would be two way, low cost and modifiable. The "crew" consists of H.S. and early collage age boys (strong). We are hoping to transmit and receive across miles from one mountain top to another and hike the gear such as small telescopes, laptops and electronics. The typical laser pen modulated by a serial port output and plastered all over YouTube won't cut it, but at the same time an expensive, "black box" solution won't provide any hands on learning. The ideal would be a system that is straight forward and for example might be modified by substituting a 150mm catadioptric telescope for a "supplied" 6mm lens. Or, the electronics are there and we/they supply the diode and optics. If operation out of the KHz range and into the MHz range would provide WiFi like connectivity,that would be good as well, but is not critical. Any suggestions or leads would be appreciated.

[CountFunkula]

http://ronja.twibright.com

Reasonable Optical Near Joint Access. Open Source, 10+Mbps link speed.

Some leads on R.O.N.J.A. system parts: http://ronja.twibright.com/get/

R.O.N.J.A. schematics and dev info: http://ronja.twibright.com/development/ http://ronja.twibright.com/schematics/

Hope that helps!

[mixedgas]

I have some experience in this matter.

BTW, incoherent LED does better long haul then laser in some respects, over a certain threshold distance, mainly in bandwidth. Laser can suffer from group delay and other issues with respect to scintillation.

Would you like some ham radio microwave gear?, perhaps I can help as that is the "other" hobby at 10 Ghz and some other frequencies. Desired Distance?

http://www.bluehaze.com.au/modlight/

I also have a few 10 watt LEDs if your game, I can drop one in the mail, and I'm sure DTR will have some from Ca$io pojectors.

Going to narrow bandwidth allows signal recovery over distance. I'd love to see what the Auzzies could have done with Avalanche Photodiodes.

Steve

[planters]

Incoherent may be the way to go as we are willing to use some pretty big optics if necessary. We are looking at up to 15 Mi. We have some good size LiFePhos batteries and so power abounds. Where I am out of my comfort zone is the comp to modulation and detection to comp parts of the train. The microwave would be a kick as my older son is into FM and AM radio, but I don't want to get too distracted at this stage.