RE: Re: [OT] [Possibly] WiFi WLAN update..

["Ian Lowe" <ian@xxxxxxx>]

From: andylaurence [mailto:andy@xxxxxxx]
>>That's 13,920 metres away
>
>Word of warning: a wireeless link over this distance *will* be
illegal.

err.. you sure?

I really, honestly, don't understans the maths involved any more, but I
was
under the impression that using a CE marked, UK sold WiFi Card, the
radiated
power should be within the legal limit using an antenna of up to 21db
Gain.

It's one of the reasons I chose 19dbi antennas, max power whilst
staying
legal..

> When you say you have LOS, do you mean you can see
> eachother, or you have radio LOS?  The two are mutually
exclusive.

I don't know about that Andy! I know that RF LOS and Visual LOS are not
the
same thing, but they are not mutually exclusive!

I have some concerns about a) some trees at about 500m from me, and b)
a
tower block at about 2 degrees off line and 6km out, which *may*
protrude
into the fresnel zone. If the trees are a problem, they are on old
commercial ground *cough* chainsaw *cough* the tower block is more of a
problem, but I think it's far enough out of line..

>For perfect signal quality, you need clear space in an elliptical
area
>between the two aerials.

Agreed, but we have a bit of gain to play with. not to mention that
whilst
11Mbps would be nice, for sharing a 1Mb DSL connecion (the ulterior
motive
here) we really don't need that much. I would be happy to get a 2Mb
Direct
Sequence connection going.

>You'll need some good gain on the antennae to get that distance,

hence, buying a commercially manfactured antenna rather than trying
some
Pringles can hilarity. ;)

>but it's not impossible by any means.

Well, given Lucent are selling 25Km capable bridging gear, 14km should be
a
walk in the park :D

>Is your plan to hook up two 24dB antennae and hope for the best?

Well, we have spent quite a bit of time driving around with Orinoco +
Laptop
plotting WLANs, to ensure we don't stomp over someone, getting GPS fixes
on
almost everything taller than six storeys and trying to see if it will
fly..

but ultimately, yes.. it's a question of fire it up and see. :D

>Community (wireless) networking for Bristol
>http://consume.andylaurence.co.uk

As an aside Andy, are you guys using all short local hops in Bristol, or
are
there any big links involved there?




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