D&C GLug - Home Page

[ Date Index ] [ Thread Index ] [ <= Previous by date / thread ] [ Next by date / thread => ]

Re: [LUG] Connecting two points 500m apart

 

On Wed, 16 Jun 2010, James Andrews wrote:

Where I work we had a slightly different problem, less than 500m but poor
reception so we used one of these

http://www.ubnt.com/bulletm

With a very large omni antenna

Intersting. If it's 600mw ERP then I'm fairly sure it's illegal in the UK - max is 100mw ERP in the 2.4GHz Wi-Fi band from what I recall...

However, directional and high gain antennae is the way to go. Longest Wi-Fi link we ran was 6.5 miles from a 12db omni to an 18bd grid antennae. That was clear line of sight though, and those antennae were expensive a the time. (We also ran a 17.5 mile 10Mb link but that was on posher kit with a 2' dish at either end)

Power over mains won't work - too far and you'll never get the same ring over that distance anyway.

And your budget of £100 is going to rule out almost anything else.

Is it clear line of sight? If so, then a pair of good Wi-Fi access points acting in bridge mode might just work. (And even if you do have line of sight, lookup fresnel zone - it'll be a factor at that distance)

And I'm guessing you want "Ethernet" speeds too. If less, then rs232 might work ;-)

Or a pair of baseband modems - you'll get 2Mb/sec or more - possibly even 8Mb if you have good twisted pair copper. (or multiple pairs)

The downside is the cost of the modems and ethernet adapters.

I'd go back to the Wi-Fi access points in bridge mode. Trouble is, as I found out recently, most are over 50 quid when bought without an adsl router! And then, what do you do with one that has 2 antennae? Which one do you pick to plug the directional antennae into? And then there's the cost of the directional antennae to connect to it, and cabling - basically I think you're stuffed for that budget. Might as well use mobile data, or install a 2nd ADSL line at the far-end and use a VPN...

Gordon
-- 
The Mailing List for the Devon & Cornwall LUG
http://mailman.dclug.org.uk/listinfo/list
FAQ: http://www.dcglug.org.uk/linux_adm/list-faq.html