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On Sat, 1 Aug 2009, tom wrote: > Gordon Henderson wrote: >> .... >> The problem we had (runing community Wi-Fi broadband access) was always >> the last mile. (and to a lesser extent, the first mile) E.g. in Devon, we >> had 10Mb connectivity from our base at Sowton to the mast at Marldon above >> Torbay, then from there we had a 5.8GHz link of some 17.5Km to a farm high >> up on Dartmoor, then another 5.8GHz link from there to another farm above >> Buckfastleigh, then from there via 2.4GHz Wi-Fi links to a series of >> access points in town. We had similar issues in Cornwall too >> (Penwith/Lands End area) >> ... > Sounds like pringles aerials required. No it doesn't We were doing it properly with very good and expensive outdoor kit, guaranteeing line of sight with minimal fresnel zone intrusions between our relay stations. Pringles cans are an abomination to work with. They go soggy in the rain and are not even a cheap substitute for the real thing. We had Ethernet to the box which was outdoors with proper power over ethernet to the radio units. None of this co-ax nonsense. The 17.5Km line was a pair of 2' diameter dishes for example. You're not going to do that with pringles cans. That was between a pair of (now positively ancient by comparison to todays products) Apperto 5.8GHz units. The longest Wi-Fi (2.4GHz) link we ran was just over 6 miles - and the recipient had an 18db grid parabolic antennae pointing at a 12db omni. Line of sight all the way. > I must try and get in touch with the techies at bristol connect(?) > @2.4/5.8G it should be possible to know up reasonably effective helical > aerials for point to point - just a few turns of copper wire on a > lathe.. now wheres my old uni notes..... Everything you need for this sort of thing is off the shelf these days, and while it's fun to build, sometimes you want something that just works. It does annoy me when people say thing like "just use a pringles can". It's obvious that they've never tried to build a commercial network out of them, nor had to deal with non line of sight communications. Incidentally this project went bust for several reasons - the cost of install was too high and BT ADSL enabled all the exchanges. 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