Wireless point to point link for broadband

I am too far away from my local exchange to get ADSL but I have found
a willing partner who can get broadband and have been looking at the
options to link to his service via a wireless link. We have direct
line of sight with a distance of 1.5Km. I am looking at Netgear
Antenna for the purpose. One snag I have hit is that the line of
sight goes straight through national grid high voltage electricity
lines between two pylons. Does anyone know or can anyone point me to
a source of expertise that would tell me if the electromagnetic field
around the lines would screw up the wireless transmission? I would
hate to buy all the gear for it not to work for this reason!

On Wed, 22 Jun 2005 18:04:28 +0100,it is alleged that Chris
<(E-Mail Removed)> spake thusly in
uk.telecom.broadband:

>I am too far away from my local exchange to get ADSL but I have found
>a willing partner who can get broadband and have been looking at the
>options to link to his service via a wireless link. We have direct
>line of sight with a distance of 1.5Km. I am looking at Netgear
>Antenna for the purpose. One snag I have hit is that the line of
>sight goes straight through national grid high voltage electricity
>lines between two pylons. Does anyone know or can anyone point me to
>a source of expertise that would tell me if the electromagnetic field
>around the lines would screw up the wireless transmission? I would
>hate to buy all the gear for it not to work for this reason!

The electromagnetic field around the lines will be 50Hz, wireless
ethernet runs at 2.4 GHz, so the field itself wouldn't be a problem.
What might be a problem is the distance, 2.4GHz is in the microwave
region, and we all know what water does to microwaves (think rain).
Also I am not sure if reflection/obstruction from the metal of the
cables would be an issue.

--
There is not the slightest indication that nuclear energy will
ever be obtainable. It would mean that the atom would have to
be shattered at will.
- Albert Einstein, 1932

On Wed, 22 Jun 2005 18:04:28 +0100, Chris
<(E-Mail Removed)> wrote:

> Does anyone know or can anyone point me to
>a source of expertise that would tell me if the electromagnetic field
>around the lines would screw up the wireless transmission?

I wonder if you may pick up interference with your aerial focussed on
the grid lines, you pick a lot up on a car radio driving underneath
them.

Get Netstumbler and a compatible wireless card in a laptop and go sit
underneath. I might even try it myself :-)

I have also asked someone who may know.

Phil
--
Tiscali - dialup speeds at Broadband prices, see
http://bbs.adslguide.org.uk/postlist...&Board=tiscali

AOL - the unlimited ISP of choice for heavy downloaders.

On Wed, 22 Jun 2005 18:04:28 +0100, Chris
<(E-Mail Removed)> wrote:

>I am too far away from my local exchange to get ADSL but I have found
>a willing partner who can get broadband and have been looking at the
>options to link to his service via a wireless link. We have direct
>line of sight with a distance of 1.5Km. I am looking at Netgear
>Antenna for the purpose. One snag I have hit is that the line of
>sight goes straight through national grid high voltage electricity
>lines between two pylons. Does anyone know or can anyone point me to
>a source of expertise that would tell me if the electromagnetic field
>around the lines would screw up the wireless transmission? I would
>hate to buy all the gear for it not to work for this reason!

You should get some good responses from alt.internet.wireless where
some knowledgeable guys hang out. F/ups set.


--
AnthonyL

>
>Get Netstumbler and a compatible wireless card in a laptop and go sit
>underneath. I might even try it myself :-)

Thanks. I have a Centrino laptop but on reading the info with
Netstumbler I am not sure this will help or tell me anything.
>
>I have also asked someone who may know.
>
>Phil

That would be great as I am really venturing way beyond my knowledge
base here. I am looking at using 2 x Netgear ANT24D18 antenna with
appropriate wireless devices at each end and the whole caboodle will
cost around £350 which I am reluctant to spend if it is not likely to
work!

On Wed, 22 Jun 2005 20:44:40 +0100, Chris
<(E-Mail Removed)> wrote:

>Thanks. I have a Centrino laptop but on reading the info with
>Netstumbler I am not sure this will help or tell me anything.

it gives you signal and noise graphs, so you could drive under a
powerline or point an antenna at it and see if you get loads of extra
noise.

Phil
--
Tiscali - dialup speeds at Broadband prices, see
http://bbs.adslguide.org.uk/postlist...&Board=tiscali

AOL - the unlimited ISP of choice for heavy downloaders.

Chip:
>and we all know what water does to microwaves (think rain).

Rain does NOT affect my wifi - over 75m of open space.
Regards,
Martin

> Rain does NOT affect my wifi - over 75m of open space.

Yes, it's probably not evident over that range, but microwave ovens do
use 2.4 GHz, because that's the specific range of frequencies that
excites water molecules, thus causing them to vibrate and heat up. Over
longer distances rain will certainly have an effect. Other (typically
higher) microwave frequencies are not affected anywhere near as much, if
at all.

One further caveat:

2.4 GHz systems in the UK may not legally transmit at more than 100 mW
(20 dBm) EIRP (see
http://www.ofcom.org.uk/static/archi...df/ir2005.pdf),
and the omni-directional antennas included with most WiFi gear provide
enough gain for that level or something just below it.

Adding a high gain directional antenna is therefore not permitted unless
the transmit power of the radio is reduced sufficiently to maintain the
20 dBm EIRP.

Ray

On Wed, 22 Jun 2005 20:44:40 +0100, Chris
<(E-Mail Removed)> wrote:

>Thanks. I have a Centrino laptop but on reading the info with
>Netstumbler I am not sure this will help or tell me anything.

well, I parked under a bit of heavy duty grid pylon cabling. This took
out the AM radio with a very loud buzz but FM worked fine.

Netstumbler needs an access point to trigger it into displaying the
stats, so I moved down the road where I could get a house with an open
access point between me and the pylon. Downloaded an antivirus update
will clocking the figures - the interfeence level was -100 dBm and it
changed little if I aimed at the pylon or away from it. Signal was -75
to -80 dB so plenty of SNR.

Outside a Little Chef on the A1 I got -98 dB of noise so there is no
appreciable interference to 802.11b from grid pylons.

Look up "fresnel zone" on Google, the wires and pylons may cause a
bit of grief.

Phil
--
Tiscali - dialup speeds at Broadband prices, see
http://bbs.adslguide.org.uk/postlist...&Board=tiscali

AOL - the unlimited ISP of choice for heavy downloaders.

Many thanks. On the advice of someone in this newsgroup I made a
posting in alt.internet.wireless and have had some helpful responses
including one that should help me calculate whether or not the setup I
am contemplating will work. I am missing the transmit power of the
Netgear DG834g at the moment. They give it for the WG602 but not the
router so I have emailed them.

On Thu, 23 Jun 2005 20:41:30 +0100, Phil Thompson
<(E-Mail Removed)> wrote:

>On Wed, 22 Jun 2005 20:44:40 +0100, Chris
><(E-Mail Removed)> wrote:
>
>>Thanks. I have a Centrino laptop but on reading the info with
>>Netstumbler I am not sure this will help or tell me anything.
>
>well, I parked under a bit of heavy duty grid pylon cabling. This took
>out the AM radio with a very loud buzz but FM worked fine.
>
>Netstumbler needs an access point to trigger it into displaying the
>stats, so I moved down the road where I could get a house with an open
>access point between me and the pylon. Downloaded an antivirus update
>will clocking the figures - the interfeence level was -100 dBm and it
>changed little if I aimed at the pylon or away from it. Signal was -75
>to -80 dB so plenty of SNR.
>
>Outside a Little Chef on the A1 I got -98 dB of noise so there is no
>appreciable interference to 802.11b from grid pylons.
>
>Look up "fresnel zone" on Google, the wires and pylons may cause a
>bit of grief.
>
>Phil