In article ,
T i m wrote:

If you don't have true line of sight, then you're shafted.

I sorta do Gordon. From the window in the spare (junk) room I can
clearly 'see' the workshop.

OK. You are in with a good chance. I'd still go with an outdoor antennae
if possible though.

I've built community broadband networks with various units - the favourite
is the Smart Bridges range - they have various flat-plat directional
units which are reasonably good in bridge mode, and more importantly,
weather proof and take power over Ethernet. The ones we use are about
7" square.

Is this 'legal' then Gordon. That panel seems likely to gave a gain
greater than unity?

I'm not that hot on the technical side of things (Internet, IP, routing,
etc. is my area of expertiese, however you learn a lot when working with
the radio heads!)

As far as I could tell yes - the radios insude the units are matched
the the flatplate (actually they look like a foil pie dish!) units to
keep the ERP to legal levels...

Power over Ethernet means that you just run one cable to the outdoor unit,
and that cable is a digital data cable,

Like USB . didn't know you could get such but it makes sense.

Isn't there is distance limit of USB cables though? If not, it might be
an option in the workshop then. I've run 50M cables to these units in the
past.

rather than an analogue RF signal,
which at the power levels avalable to you in WiFi applications is woefully
weak and prone to cable, and connector losses.

Indeed ;-(

It can be done, but you need expensive cable and connectors - I've used
some units which have external co-ax plugs and cables though, but we
still ran ethernet right up tothe device, then connected it to an omni
or grid parabolic via a veryshort patch lead.


I have one link that 7.5Km long, and it's providing and acceptable signal
for the home user, but they have a rather large grid parabolic reflector
on the chimney of their house pointing back to the base station... So
with care and the right kit, quite a lot is possible.

Hmm, so if you were to 'reflect' (concentrate) the signal would that
stay within the rules? What would be the practical difference then re
using a Yagi?

Yagis, etc. are all just differetn types of antenna. You need a base
station which has a co-ax outlet and a bit of cable to connect to the
antenna. You have to do sums like multiply the output power by the gain
of the antennae then subtract the losses in the cables and connectors -
in extreme cases, adding an external antennae can actually reduce the ERP.

Saying all that, you might be lucky with ordinary kit - radio waves do
reflect - but they will be severely attentuated by trees with leaves on
-I have some graphs that look great in the winter... Come spring when
the sap starts to rise and you can see the signal strength drop )-:

All concrete here ;-) I *did* have a pretty reliable link using a
Netgear AP to a Netgear USB unit (not dongle) but the AP seems to have
died and a Belkin WiFi router has taken it's place for the moment
running in AP mode.

When we did tests, Netgears seemd reasonable, and I have a really old
Belkin at home which I use from time to time and it seems better. DLink
gave the worst performance of the lot of them.

but IIRC we were paying
something like £150 each for the smartBridge units...

Ouch! A bit outside my league I'm afraid .. hence the 'DIY' interest

Indeed - and this is why commnity WiFi projects will never fly )-: It
simply costs to much to build the infrastructure and people just won't
pay the real home install costs - it was costing us something like
£250 per punter in real terms to put a unit on the side/roof of their
house.. charging them £99 which was all they would be prepared to spend
meant we made a loss for a very long time...

Gordon