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On Wednesday 05 February 2003 6:00 pm, Jon Gerdes wrote:
> Do you need line of sight between transmitters?
yes, for anything over ~ 300m, although it varies a little, you'll be damn
lucky to get anything more than 500m even going through a few tall trees
(i've tried it here, it works when it's dry, then when it rains, it all
breaks, and thats only ~ 400m and maybe 5 trees).
> What is the true range?
I've got just over 13km iirc, in london, though it was a long time ago now, so
things have probably improved.
There are a number of htings you can do to improve range, although bear in
mind reglusations only allow 100mW EIRP for wavelan, and max gain on transmit
is 14dBi (14dB ggain over an isotropic radiator), however, you can have
unlimited gain on recieve so if you can find some cards that have 2 external
antenna ports and use one for transmit (and push only the legal limit) and
one for recieve (whith a 24db antennal), thoguh i'm not sure where to find
them ;-)
A mail from old proposals i just dug out we did a while back:
{ Max power out of a card is +15dBm (15dB more over 1mW) approx = 32mW}
{ The reduced power one is +8dBm = approx 5mW.}
{ So +8dBm with a 14dBi antenna = 8+14 - 2 for cable losses = 20dBm = 100nW}
a guess would probably be 15 km line of site with real decent equipment, no
interferance, and good weather, while still keeping it legal.
see the wireless telegraphy act 1947, and all the ammendments sice then for
true legal advice, i barly understand why you can't walk outside naked, let
alone how all this radio stuff works, so don't take the above as gospel :p
> Who does the best gear?
lucent's top end orinoco kit is the best imho, thoguh a tad expensive compared
to others (~700 for a nice AP without cards last time i looked).
> Planning regs?
depends on your local area, and how big the ariels are. I've got one on a
tall (6 metre) scaffolding pole, that very nicly looks like my washing line
(i even added some washing line to it so it looks just perfect), and got away
with it, no neighbours have complained (and i've asked them). Anything more
obvious that intrudes badly will probably need permission, although i'm not
expert on real life things ;)
> Interferance with existing 2.4GHz stuff?
same rules as any radio signal stuff, really. I've seen a TV remote control
extender (that extends your remote to work in another room) break wavlan
completly - god knows why.
Although i've not proved it, mobile phones also caused me a fair bit of
trouble in small spaces.
> Realistic performance (11 or 22Mb - really!) ?
no way. You'll be lucky to shift a true 4mbit over it, the most i've ever
seen in 3 years of working a fair bith with wavelan is around 6 mbit, and
that was in the middle of the country ;)
I've not touched 22mb, until it's a standard i'm not going to. But i'd like
to see it in action, and actually be noticably faster.
~ Theo
- --
Theo Zourzouvillys
<theo@xxxxxxxxxxxxxxxx>
<http://theo.me.uk/>
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