OT. BT Midband

> >
> >
> >>You need a license to use WLAN at that kind of range.
> >
> >
> > Really? You got a reference for that Alun?
>
> The maximum unlicensed power limit in the license-exempt bands
> such as 2.4GHz is 4W. Whether commercial wlans
> run at that level I don't know, as the IEEE802.11b
> only claims 50m range. You could try looking in ofcom.org.uk.
>
> - Keith
>
The maximum EIRP for 2.4Ghz is 20dBm.

If you look at this spread sheet that Cisco provide you can get some
guesstimates of the sorts of ranges you can get in theory.

By using very sensitive aerials you can get a range in excess of 4 miles at
11Mbs and it will still be legal, dropping down to 1Mbs then you can get a
theoretical range of 11miles but then you get other issues with curvature of
the earth.

Darren Soothill wrote:
> The maximum EIRP for 2.4Ghz is 20dBm.
>
> By using very sensitive aerials you can get a range in excess of 4
> miles at 11Mbs and it will still be legal, dropping down to 1Mbs then
> you can get a theoretical range of 11miles but then you get other
> issues with curvature of the earth.

The trouble is it's line of sight stuff. I run a lot more
power than that on an overlapping band but you can't see
it standing on my roof you can't work it.

nigelH
Wideband ATV.

Darren Soothill wrote:

> The maximum EIRP for 2.4Ghz is 20dBm.

Hum, in fact 4W EIRP is the max for America. In
the UK according to EN 300.328.1 it's 100mW.
Are the ranges you quote for US or UK based
power levels?

- Keith

"Darren Soothill" <darren@soothill.com> wrote ...

> > >>You need a license to use WLAN at that kind of range.

> > > Really? You got a reference for that Alun?

> > The maximum unlicensed power limit in the license-exempt bands
> > such as 2.4GHz is 4W. Whether commercial wlans
> > run at that level I don't know, as the IEEE802.11b
> > only claims 50m range. You could try looking in ofcom.org.uk.

> The maximum EIRP for 2.4Ghz is 20dBm.

> If you look at this spread sheet that Cisco provide you can get some
> guesstimates of the sorts of ranges you can get in theory.

> By using very sensitive aerials you can get a range in excess
> of 4 miles at 11Mbs and it will still be legal, dropping down
> to 1Mbs then you can get a theoretical range of 11miles but then
> you get other issues with curvature of the earth.

As Nigel says it's all line-of-sight stuff as we're up in the 5GHz range
here. My little WLAN bridge runs at only 22mw, I've heard of people sticking
aerials on them and getting a few Km's between bridges with no problem.

Keith L

"Keith Lawrence" <false@nospam.com> wrote in message
news:4035eeab$0$4096$5a6aecb4@news.aaisp.net.uk...
> "Alun Harford" <alunharford@yahoo.com> wrote
>
> > > > > Immediate thought is to find a geek/friend that =IS= near
> > > > > enough to the exchange, for a couple of hundered quid or so
> > > > > you could WLAN bridge it (2 or 3 km shouldn't be a problem)
> > > > > and then go halves on the ADSL
>
> > > > You need a license to use WLAN at that kind of range.
>
> > > Really? You got a reference for that Alun?
>
> > Nope. Sorry - but I remember it was a potential problem when I was
> looking
> > into doing exactly what you suggested above.
>
> There have been some huge changes in licensing of late, things are still
in
> a state of flux. The nearest thing I can come up with is -
>
http://www.ofcom.org.uk/licensing_nu...rlans_licensin
g/?a=87101
>
> This one could be worth a call to Ofcom, my understanding is that low
> powered private 802.11b/g point-to-point links are exempt from licensing
> requirements but I could be wrong on that.
>
> K
>
>

Well,

Frequency allocation tends to be an international issue and the 2,4 GHz band
tends to be exempt of licensing in everywhere in Europe and mostly elsewhere
too regardless of what you decide to do with it. There are some basic
conformance sules, sort of "good citicenship" regulations, but mostly it's a
pretty wild world out there. I'm no expert on the particular license
conditions in the UK, but do know a fair bit about them in Scandinavia. The
two documents below should also cast some light on this from UK standpoint.

http://www.ofcom.org.uk/static/archi...ans-licence-ex
empt/licenceexemptioncondocfinal.doc

http://www.ofcom.org.uk/static/archi...cs/other/y32a0
18a/y32a018a-finalreport.pdf

One problem with building long links with 802.11b at least is that you tend
to get a lot of interference from other devices on the same (unlicensed)
band. This includes other 802.11 stations, Bluetooth devices, stadium lamps,
microwave ovens, etc. So, even if in theory you should get the link working
it does not necessarily happen in practice.

Regards,

Timo

"Keith S." <false@ntlworld.com> wrote in message
news:c14f0j$1bu3p1$1@ID-169434.news.uni-berlin.de...
> Keith Lawrence wrote:
> > "Alun Harford" <alunharford@yahoo.com> wrote...
> >
> >
> >>>Immediate thought is to find a geek/friend that =IS= near
> >>>enough to the exchange, for a couple of hundered quid or so
> >>>you could WLAN bridge it (2 or 3 km shouldn't be a problem)
> >>>and then go halves on the ADSL
> >
> >
> >>You need a license to use WLAN at that kind of range.
> >
> >
> > Really? You got a reference for that Alun?
>
> The maximum unlicensed power limit in the license-exempt bands
> such as 2.4GHz is 4W. Whether commercial wlans
> run at that level I don't know, as the IEEE802.11b
> only claims 50m range. You could try looking in ofcom.org.uk.

Exactly. 4W is building to building (about 200metres at most - if you want
it to actually work)
You need far more powerful transmitters to get it to work over a few
kilometers.

Alun Harford

"Alun Harford" <alunharford@yahoo.com> wrote in message
news:c132hl$fug$1@pegasus.csx.cam.ac.uk...
> "Keith Lawrence" <false@nospam.com> wrote in message
> news:40350d28$0$4101$5a6aecb4@news.aaisp.net.uk...
> > "Graham Bowers" <graham@nospam.frzzserve.co.uk> wrote...
> >

> > 3 km shouldn't be a problem) and then go halves on the ADSL
>
> You need a license to use WLAN at that kind of range.
>
Actually for the available equipment which delivers <1 Watt of power you
don't.
I have a community wireless service running at the moment for wireless
devices up to 802.11g; It is reliable and fast.

For links to Wireless ISPs try:-

http://dmoz.org/Regional/Europe/Unit...ders/Wireless/

"Keith Lawrence" <false@nospam.com> wrote in message
news:4035efe9$0$4105$5a6aecb4@news.aaisp.net.uk...
> "Darren Soothill" <darren@soothill.com> wrote ...
>
> > > >>You need a license to use WLAN at that kind of range.
>
> > > > Really? You got a reference for that Alun?
>
> > > The maximum unlicensed power limit in the license-exempt bands
> > > such as 2.4GHz is 4W. Whether commercial wlans
> > > run at that level I don't know, as the IEEE802.11b
> > > only claims 50m range. You could try looking in ofcom.org.uk.
>
> > The maximum EIRP for 2.4Ghz is 20dBm.
>
> > If you look at this spread sheet that Cisco provide you can get some
> > guesstimates of the sorts of ranges you can get in theory.
>
> > By using very sensitive aerials you can get a range in excess
> > of 4 miles at 11Mbs and it will still be legal, dropping down
> > to 1Mbs then you can get a theoretical range of 11miles but then
> > you get other issues with curvature of the earth.
>
> As Nigel says it's all line-of-sight stuff as we're up in the 5GHz range
> here. My little WLAN bridge runs at only 22mw, I've heard of people
sticking
> aerials on them and getting a few Km's between bridges with no problem.

Then... err... have you ever tried to get the damn things to work over a
large distance?
Bear in mind that two people transmitting on the same channel screws up the
system.

Alun Harford

In article <c132hl$fug$1@pegasus.csx.cam.ac.uk>,
Alun Harford <alunharford@yahoo.com> wrote:
>"Keith Lawrence" <false@nospam.com> wrote in message
>news:40350d28$0$4101$5a6aecb4@news.aaisp.net.uk.. .
>> "Graham Bowers" <graham@nospam.frzzserve.co.uk> wrote...
>>
>> > Having been turned down for ADSL again (too far from the
>> > exchange) I'm considering BT midband.
>> > Anybody in here tried it and have comments please??
>>
>> Personally I wouldn't go near anything to do with BT
>>
>> Immediate thought is to find a geek/friend that =IS= near enough to the
>> exchange, for a couple of hundered quid or so you could WLAN bridge it (2
>or
>> 3 km shouldn't be a problem) and then go halves on the ADSL
>
>You need a license to use WLAN at that kind of range.

er ... you don't, and I do this for a living. (It doesn't pay much though ):

What you do need for this range is very clear line of sight and decent
outdoor units and good directional antennae, and before you go any
further, lookup Fresnel Zone intrustions if you can think you can get away
with it in non-line of sight situations... (With UK power levels and the
equipment you can buy, you really can't do it reliably without true line
of sight, and then some) I currently have a few 5Km links running in
my network, which are acceptable, but they aren't the best of quality.
(I also have a 17Km link running at 12Mb/sec, but thats in a licensed
band and a different kettle of fish entirely!)

A pair of good outdoor units will cost you in the region of £300 plus
brackets & fitting. External antennae might be up to £50 each.

As for BT midband, well it's a crap ISDN offering from BT. If you really
are marginal for ADSL, I'd wait a while and see what they come up with
next. Rumours I'm hearing that they are looking at going over their
current 6Km range (but it's really line loss/quality that governs it,
not absolute distance)

Or rather than BT midband, just get HomeHighway and a BT Together package,
then look for Surftime/AnyTime ISPs and juggle the figures until you
find something thats affordable. My home backup (to the WiFi broaband)
is a 24/7 ISDN (Home Highway) line via Demon, but thats expensive, and
I'm probably going to cancel my Surftime/Anytime and Demon accounts soon
and go back to an 0845 ISDN dialup if I need it)

Gordon

"Graham Bowers" <graham@nospam.frzzserve.co.uk> wrote in message
news:c12tbc$onv$1@news6.svr.pol.co.uk...
> Having been turned down for ADSL again (too far from the exchange) I'm
> considering BT midband.
> Anybody in here tried it and have comments please??
> Cheers
> Graham
> header is munged. replace nospam with bbowers36 and correct obvious
spelling
> mistake
>
>

Aren't there any reasonably priced sattelite offerings? you just need a 56K
dialup to send your reqests for data and the ISP sends the data via 1Mb/Sec
or greater microwave sattelite from orbit.

rhys