Build your own free space optics data link
 

In case anyone is interested

http://ronja.twibright.com/

Re: Build your own free space optics data link
 

Good idea but I suspect that wireless is cheaper and faster:
http://www.frars.org.uk/cgi-bin/render.pl?pageid=1066

Re: Build your own free space optics data link
 

certainly it has distance advantages and point to multipoint advatages and possibly cost advatages as well.

however wifi also has it's disadvatages. For a start the 11mbs (for which you need a _good_ signal) give a throughput nearer 5mbs in reality.

interferance issues are another disadvantage

As far your link goes - I am sure they were not operating within the UK legal limits of 100mw EIRP. You just can not get that sort of range within 100mw EIRP - at least as I understand it.

For me affordable (read - build your own) free space optics complement wifi / wireless and wired options for community / self built networks and as such I welcome the ronja project.

Now all I have to do is find someone willing to build me one :)

Re: Build your own free space optics data link
 

Yep, the radiated power limit defined by ETSI is 100mW EIRP (or +20 dBm). I think that applies across the whole of Europe. Because, in America, they define the transmitter power instead, the limits are effectively much higher. Some details here:
http://www.cisco.com/application/vnd...00800a912a.xls
http://www.cisco.com/warp/public/102...re-us-calc.xls

Re: Build your own free space optics data link
 

OFCOM is currently looking at increasing the limits for outdoor use in rural / remote areas (200mw has beem suggested)
Also it's worth noting that 5.8ghz band C has an outdoor limit of 2w - though there is a 'light licensing' requirment to use this and compliant kit is a bit thin on the ground right now