Info needed on possible factors affecting signal range

Hello all

I've operated a wireless network at home for a couple of years now and never
needed this group up until now, so please forgive me if I'm asking questions
that are common knowledge (I have already checked out Google groups for
possible answers, but with no success).

Anyway, the issue is this:

I was able to implement an SMC Barricade (SMC7004AWBR) with an unencrypted
802.11b WLAN from the top shelf in an upstairs room at the front of my
house, and was able to get a strong enough signal in the back garden on a
Dell laptop with a Belkin PC card (F5D6020u). Proof of concept achieved,
I've not bothered using it in the garden since then.

In the meantime I temporarily retired said laptop/PC card and implemented
128 bit security on the WLAN. I've also added in an Ethernet network drive,
which is connected to the Barricade but sits on the shelf below it.

Now that I've started using the WLAN in earnest again I've noticed that I'm
getting a poorer link quality, and am having trouble maintaining a link in
the room almost directly underneath the router. In fact, the Dell laptop/PC
card combo signal strength indicator leaps around all over the place from
"Excellent" to "Not Connected" even when it is in the same room as the
router (a second laptop, an HP with built-in WLAN capability is ok).

Is encryption giving a poorer signal, or is the presence of another
electronic device that is causing problems? Or is it both? Can my particular
wireless router have its antenna upgraded to solve this problem? Is there
anything else I can do? Physics isn't my strong point - I just want things
to work!

--
Thanks in anticipation


Martin




Martin Lowe

On Fri, 03 Feb 2006 10:16:15 GMT, in alt.internet.wireless , "Martin
Lowe" <(E-Mail Removed)> wrote:

>Now that I've started using the WLAN in earnest again I've noticed that I'm
>getting a poorer link quality,
>
>Is encryption giving a poorer signal, or is the presence of another
>electronic device that is causing problems?

Did you buy some new cordless phones, or a video sender, or a new
microwave? The first two use the same frequency as 802.11b/g, the
latter generates interference.

Mark McIntyre
--

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Mark McIntyre wrote:
> On Fri, 03 Feb 2006 10:16:15 GMT, in alt.internet.wireless , "Martin
> Lowe" <(E-Mail Removed)> wrote:
>
>> Now that I've started using the WLAN in earnest again I've noticed that I'm
>> getting a poorer link quality,
>>
>> Is encryption giving a poorer signal, or is the presence of another
>> electronic device that is causing problems?
>
> Did you buy some new cordless phones, or a video sender, or a new
> microwave? The first two use the same frequency as 802.11b/g, the
> latter generates interference.
>
> Mark McIntyre
The OP is in the UK and DECT phones work from 1.88Ghz to 1.9Ghz so
shouldn't cause interference.

Bob

Mark McIntyre <(E-Mail Removed)> wrote in
news:(E-Mail Removed):

> On Fri, 03 Feb 2006 10:16:15 GMT, in alt.internet.wireless , "Martin
> Lowe" <(E-Mail Removed)> wrote:
>
>>Now that I've started using the WLAN in earnest again I've noticed
>>that I'm getting a poorer link quality,
>>
>>Is encryption giving a poorer signal, or is the presence of another
>>electronic device that is causing problems?
>
> Did you buy some new cordless phones, or a video sender, or a new
> microwave? The first two use the same frequency as 802.11b/g, the
> latter generates interference.
>
> Mark McIntyre

The latter also operates in the 2.4Ghz range, which is why it would cause
interference. A leaky microwave that is. That is the resonant frequency of
water, which is how the microwave operates, and why trees full of leaves
absorb 2.4 GHz frequencies.

I've actually seen a few article's about using the magnetron from a
microwave oven to build hi power amplifier's.

On Sat, 04 Feb 2006, in the Usenet newsgroup alt.internet.wireless, in article
<Xns9760756A7AB1Bidispcom@216.196.97.142>, DanS wrote:

>I've actually seen a few article's about using the magnetron from a
>microwave oven to build hi power amplifier's.

Got any cites? A magnetron is a power oscillator - there is a power
source, a magnetic field, and one RF terminal (coax or waveguide depending
on frequency range). There is a an amplifier based on the same
principles as the magnetron, called a "Crossed-Field Amplifier", but they
are comparatively rare, and of limited usefulness (they are limited in
gain to about 15 dB because of feedback, and are quite noisy and very
limited in bandwidth). They are a saturated gain device, meaning the power
out is relatively independent of (RF) power in. Their advantages are a
relatively high DC to RF efficiency (60% is practical), and they can be
designed for _very_ high peak power. Converting a magnetron to act as
an amplifier would be an interesting exercise, given that you'd have to
open the tube and install an RF input connection of some kind, then
re-evacuate the tube and seal it. Try a google search for the word
"amplitron" which is a trademark for CFAs from Raytheon (the company
that "invented" the microwave oven).

Old guy

"Mark McIntyre" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...

> On Fri, 03 Feb 2006 10:16:15 GMT, in alt.internet.wireless , "Martin
> Lowe" <(E-Mail Removed)> wrote:

>>Now that I've started using the WLAN in earnest again I've noticed that
>>I'm getting a poorer link quality,
>>
>>Is encryption giving a poorer signal, or is the presence of another
>>electronic device causing problems?

> Did you buy some new cordless phones, or a video sender, or a new
> microwave? The first two use the same frequency as 802.11b/g, the
> latter generates interference.

Hi Mark

The only device we have from those you mentioned is a cordless phone. I've
unplugged it and tested connection and found no difference (in fact, the
laptop now can't connect!)

One thing I didn't mention before that springs to mind is that I'm pretty
sure I was the first to use a WLAN in my street - I only encrypted it when I
later found that there were two others (one is secure, the other isn't).

--

Martin

On Mon, 06 Feb 2006 11:56:31 GMT, in alt.internet.wireless , "Martin
Lowe" <(E-Mail Removed)> wrote:

>One thing I didn't mention before that springs to mind is that I'm pretty
>sure I was the first to use a WLAN in my street - I only encrypted it when I
>later found that there were two others (one is secure, the other isn't).

Download netstumbler or similar, install it on the lappy, and do a
site survey. You will hopefully see the your own as well as any other
WLANs and their setups (channel, encryption etc). This will help you
diagnose whether there's interference.
Mark McIntyre
--

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----= East and West-Coast Server Farms - Total Privacy via Encryption =----

"Mark McIntyre" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...

> On Mon, 06 Feb 2006 11:56:31 GMT, in alt.internet.wireless , "Martin
> Lowe" <(E-Mail Removed)> wrote:
>
>>One thing I didn't mention before that springs to mind is that I'm pretty
>>sure I was the first to use a WLAN in my street - I only encrypted it when
>>I
>>later found that there were two others (one is secure, the other isn't).
>
> Download netstumbler or similar, install it on the lappy, and do a
> site survey. You will hopefully see the your own as well as any other
> WLANs and their setups (channel, encryption etc). This will help you
> diagnose whether there's interference.

Hi again

It's allowed me to collect a whole load of data but I'm at a loss as to
interpreting it.

What I do see is two 802.11g networks on channel 11 (mine is on channel 6)
that are a lot stronger than my network. One is encrypted; the other isn't.

( SSID ) [ SNR Sig Noise ] Flags Channelbits BcnIntvl DataRate
LastChannel

( myHouse) [ 147 196 49 ] 11 40 90 110 6
( linksys ) [ 110 163 53 ] 401 800 100 540 11
( Applesandpears ) [ 101 154 53 ] 411 800 100 540 11


This is the data summary I get when the laptop is in the same room as the
router. The only think that springs to mind is that my 11b network signal is
a lot weaker than the two 11g signals. The signal drops off quite
dramatically around the house, which it never used to do.

Any further suggestions?



--

Martin

Martin Lowe wrote:
> "Mark McIntyre" <(E-Mail Removed)> wrote in message
> news:(E-Mail Removed)...
>
>> On Mon, 06 Feb 2006 11:56:31 GMT, in alt.internet.wireless , "Martin
>> Lowe" <(E-Mail Removed)> wrote:
>>
>>> One thing I didn't mention before that springs to mind is that I'm pretty
>>> sure I was the first to use a WLAN in my street - I only encrypted it when
>>> I
>>> later found that there were two others (one is secure, the other isn't).
>> Download netstumbler or similar, install it on the lappy, and do a
>> site survey. You will hopefully see the your own as well as any other
>> WLANs and their setups (channel, encryption etc). This will help you
>> diagnose whether there's interference.
>
> Hi again
>
> It's allowed me to collect a whole load of data but I'm at a loss as to
> interpreting it.
>
> What I do see is two 802.11g networks on channel 11 (mine is on channel 6)
> that are a lot stronger than my network. One is encrypted; the other isn't.
>
> ( SSID ) [ SNR Sig Noise ] Flags Channelbits BcnIntvl DataRate
> LastChannel
>
> ( myHouse) [ 147 196 49 ] 11 40 90 110 6
> ( linksys ) [ 110 163 53 ] 401 800 100 540 11
> ( Applesandpears ) [ 101 154 53 ] 411 800 100 540 11


I find these signal levels quite odd as they seem to correspond to
+47dBm in the case of "myHouse",this is more than your Wireless should
be Transmitting.When you look at the graphical display what does the
vertical axis show as signal level? Mine is normally around -50dBm.
For my network(edited):-
# $Creator: Network Stumbler Version 0.4.0
# $Format: wi-scan summary with extensions
#Time (GMT) [ SNR Sig Noise ]
17:54:36 (GMT) [ 55 104 49 ]
Gives me a signal level of -45 dBm at this time.

>
>

"Bob II" <(E-Mail Removed)> wrote in message
news:dsapde$5nf$(E-Mail Removed)...

> Martin Lowe wrote:
>> "Mark McIntyre" <(E-Mail Removed)> wrote in message
>> news:(E-Mail Removed)...
>>
>>> On Mon, 06 Feb 2006 11:56:31 GMT, in alt.internet.wireless , "Martin
>>> Lowe" <(E-Mail Removed)> wrote:
>>>
>>>> One thing I didn't mention before that springs to mind is that I'm
>>>> pretty
>>>> sure I was the first to use a WLAN in my street - I only encrypted it
>>>> when I
>>>> later found that there were two others (one is secure, the other
>>>> isn't).
>>> Download netstumbler or similar, install it on the lappy, and do a
>>> site survey. You will hopefully see the your own as well as any other
>>> WLANs and their setups (channel, encryption etc). This will help you
>>> diagnose whether there's interference.
>>
>> Hi again
>>
>> It's allowed me to collect a whole load of data but I'm at a loss as to
>> interpreting it.
>>
>> What I do see is two 802.11g networks on channel 11 (mine is on channel
>> 6) that are a lot stronger than my network. One is encrypted; the other
>> isn't.
>>
>> ( SSID ) [ SNR Sig Noise ] Flags Channelbits BcnIntvl DataRate
>> LastChannel
>>
>> ( myHouse) [ 147 196 49 ] 11 40 90 110 6
>> ( linksys ) [ 110 163 53 ] 401 800 100 540 11
>> ( Applesandpears ) [ 101 154 53 ] 411 800 100 540 11

> I find these signal levels quite odd as they seem to correspond to +47dBm
> in the case of "myHouse",this is more than your Wireless should be
> Transmitting.When you look at the graphical display what does the vertical
> axis show as signal level? Mine is normally around -50dBm.
> For my network(edited):-
> # $Creator: Network Stumbler Version 0.4.0
> # $Format: wi-scan summary with extensions
> #Time (GMT) [ SNR Sig Noise ] 17:54:36 (GMT) [ 55 104 49 ] Gives me a
> signal level of -45 dBm at this time.

Hi Bob

The graphical representation of the signal/noise is all over the place. The
highest number is roughly +41dBm, immediately followed by a low number of
usually -40dBm (but sometimes down to -100dBm every thirty seconds or so),
then followed by a number that is on average -30dBm. It cycles through the
high, low, medium number pattern.

This seems to be a more detailed representation of the WiFi card's indicator
in the system tray which cycles through poor/fair/excellent quality links;
and the card Utility screen which also cycles through
none/poor/fair/excellent quality link and signal strength.

--

Martin