Archived from groups: alt.internet.wireless (More info?)

Hi,

I have seen a lot of discussion about this, and have seen a number of
offerings, all of which seem to involve lots of "bodges" ... with pigtails,
and replacement connectors.... etc etc ...

Given that the radio signal appears to be the critical part, and the more
connectors / adapters you add the greater the signal loss, is it possible to
use a USB wifi "dongle" with a metal mesh reflector, and rely on the USB
cable to carry the digital signal ...

Would there be any snags to this approach?

What would be the maximum length of USB cable? And could a Powered USB Hub
increase this ?

Regards

John



---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.713 / Virus Database: 469 - Release Date: 30/06/2004

Archived from groups: alt.internet.wireless (More info?)

> Given that the radio signal appears to be the critical part, and the more
> connectors / adapters you add the greater the signal loss, is it possible to
> use a USB wifi "dongle" with a metal mesh reflector, and rely on the USB
> cable to carry the digital signal ...

You mean something like this?

http://www.nodomainname.co.uk/cantenna/IMG_0384s.jpg

http://www.nodomainname.co.uk/cantenna3/cantenna3.htm



> Would there be any snags to this approach?

Not really

> What would be the maximum length of USB cable? And could a Powered USB Hub
> increase this ?

USB cable length is 5m max, you can string 5 active cables together so
lets call that 25m.

David.

Archived from groups: alt.internet.wireless (More info?)

John Beeston wrote:
> Hi,
>
> I have seen a lot of discussion about this, and have seen a number of
> offerings, all of which seem to involve lots of "bodges" ... with
> pigtails, and replacement connectors.... etc etc ...
>
> Given that the radio signal appears to be the critical part, and the
> more connectors / adapters you add the greater the signal loss, is it
> possible to use a USB wifi "dongle" with a metal mesh reflector, and
> rely on the USB cable to carry the digital signal ...
>
> Would there be any snags to this approach?
>
> What would be the maximum length of USB cable? And could a Powered
> USB Hub increase this ?
>
> Regards
>
> John
>
would this be any good?

http://www.linksys.com/products/pr [...] 6&prid=612




--
Mike E

Archived from groups: alt.internet.wireless (More info?)

"David Taylor" <djtaylor@bigfoot.com> wrote in message
news:MPG.1b4f5fddec65da5e989c9a@news.individual.de...
> > Given that the radio signal appears to be the critical part, and the
more
> > connectors / adapters you add the greater the signal loss, is it
possible to
> > use a USB wifi "dongle" with a metal mesh reflector, and rely on the USB
> > cable to carry the digital signal ...
>
> You mean something like this?
>
> http://www.nodomainname.co.uk/cantenna/IMG_0384s.jpg
>
> http://www.nodomainname.co.uk/cantenna3/cantenna3.htm
>
>
>
> > Would there be any snags to this approach?
>
> Not really
>

Very impressive, but I was thinking of something far simpler ... this
approach still has mentions of brass bits, solder, and pigtails...

But there again, perhaps I do not understand the full complexities...

I was thinking more of a small self contained USB device such as the
linksys WUSB12 or D-Link DWL122 being placed at the focus of a suitable
dish and connected back to the PC using a standard USB extension cable (or
cables)

For the reflector I had something like a SKY satellite dish in mind, as
these are cheap, and easy to install.

John




---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.713 / Virus Database: 469 - Release Date: 30/06/2004

Archived from groups: alt.internet.wireless (More info?)

John Beeston <john.Beeston@talk21.com> wrote:
> I was thinking more of a small self contained USB device such as the
> linksys WUSB12 or D-Link DWL122 being placed at the focus of a suitable
> dish and connected back to the PC using a standard USB extension cable (or
> cables)

> For the reflector I had something like a SKY satellite dish in mind, as
> these are cheap, and easy to install.

The mini-USB won't properly paint a satellite dish. It might work in a
small can, like the one on David's page.
I used a DWL-122 witha 9" pie plate pretty effectively. I'm going to mount
it in the bottom of a coffee can next.

You need two coffee cans soldered together and cut off to about 6 inches,
and then mount the USB mini about half inch from the bottom end.

http://www.turnpoint.net/wireless/cantennahowto.html provides the
calculator and ideas. I was going to put the miniUSB in there, although
some experimentation to find the right focus and orientation.



--
---
Clarence A Dold - Hidden Valley (Lake County) CA USA 38.8-122.5

Archived from groups: alt.internet.wireless (More info?)

On Fri, 2 Jul 2004 12:01:29 +0100, "John Beeston"
<john.Beeston@talk21.com> wrote:

>Given that the radio signal appears to be the critical part, and the more
>connectors / adapters you add the greater the signal loss, is it possible to
>use a USB wifi "dongle" with a metal mesh reflector, and rely on the USB
>cable to carry the digital signal ...

http://www.freeantennas.com
http://www.freeantennas.com/projects/Ez-10/

The nice part is that it doesn't require an pigtails. A USB radio
should work as well. I'll leave it to your ingenuity to figure out
how to do it with a PCMCIA card in a laptop. (ribbon cable
extension?)

>Would there be any snags to this approach?

That depends on your construction abilities. There have been
aluminium foil and cardboard corner reflectors built, that I consider
to be marginal and unstable, but it can't be any worse than a
cardboard pringles can antenna.

>What would be the maximum length of USB cable? And could a Powered USB Hub
>increase this ?

16ft for USB.


--
Jeff Liebermann jeffl@comix.santa-cruz.ca.us
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 AE6KS 831-336-2558

Archived from groups: alt.internet.wireless (More info?)

Clarence, I am interested in your pie plate ... how / where did you mount
the DWL-122?

John


<dold@ExternalXa.usenet.us.com> wrote in message
news:cc40h9$ajh$1@blue.rahul.net...
>
> The mini-USB won't properly paint a satellite dish. It might work in a
> small can, like the one on David's page.
> I used a DWL-122 witha 9" pie plate pretty effectively. I'm going to
mount
> it in the bottom of a coffee can next.
>
> You need two coffee cans soldered together and cut off to about 6 inches,
> and then mount the USB mini about half inch from the bottom end.
>
> http://www.turnpoint.net/wireless/cantennahowto.html provides the
> calculator and ideas. I was going to put the miniUSB in there, although
> some experimentation to find the right focus and orientation.
>
>




---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.713 / Virus Database: 469 - Release Date: 30/06/2004

Archived from groups: alt.internet.wireless (More info?)

> Very impressive, but I was thinking of something far simpler ... this
> approach still has mentions of brass bits, solder, and pigtails...

Not in the first picture I linked you to. All that's going on there is
a the antenna from a Netgear USB NIC poked up into the cardboard tube
(foil lined).

> I was thinking more of a small self contained USB device such as the
> linksys WUSB12 or D-Link DWL122 being placed at the focus of a suitable
> dish and connected back to the PC using a standard USB extension cable (or
> cables)
> For the reflector I had something like a SKY satellite dish in mind, as
> these are cheap, and easy to install.

It has been done before but it's just as easy to stuff the antenna into
a can and use the can in the place of the LNB.

David.

Archived from groups: alt.internet.wireless (More info?)

> 16ft for USB.

or 5 active cables strung together.

Archived from groups: alt.internet.wireless (More info?)

Jeff Liebermann <jeffl@comix.santa-cruz.ca.us> wrote:
> The nice part is that it doesn't require an pigtails. A USB radio
> should work as well. I'll leave it to your ingenuity to figure out
> how to do it with a PCMCIA card in a laptop. (ribbon cable
> extension?)

I used a reflector with an Orinoco PCMCIA card.
I was holding the reflector with one hand, and the laptop with the other,
so it wasn't very useful, but NetStumbler definitely showed the effects of
the reflector being in place.
"I'll leave it to your ingenuity to figure out how to do it" in some
worthwhile fashion ;-)

--
---
Clarence A Dold - Hidden Valley (Lake County) CA USA 38.8-122.5

Archived from groups: alt.internet.wireless (More info?)

John Beeston <john.Beeston@talk21.com> wrote:
> Clarence, I am interested in your pie plate ... how / where did you mount
> the DWL-122?

I used a Marie Calendar's pie tin, which is just a touch too small of a
surface. I used double back tape to affix the mini-USB to a wall, a
window, a cookie sheet, and the pie tin. In each case, I also used
varying thicknesses of material behind the mini-USB, and settled on about
3/4" standoff from the surface.

I have some NetStumbler charts that made sense at the time, but I can't
correlate the charts to the different applications now. azimuth,
elevation, and orientation were all important. Without learnbydestorying's
help, I don't know how the antenna element in the dongle is oriented.

The pie plate was directional enough that I could see that my strongest
signal was coming in through a window, rather than a straight line through
the wall.

The coffee can is the next step, although I haven't decided how to route
the wire. The easiest would be to just run it down the side, inside the
can. Better would be poking a hole in some lined cardboard, like David
Taylor, but Pringles is way too small, so I'm going to play with the coffee
can. I only have one can, and I need two, so I'm a little slow getting
started.

Although Jeff might point out that all of my attempts are so haphazard,
a few inches of length might not be important.

---
Clarence A Dold - Hidden Valley (Lake County) CA USA 38.8-122.5

Archived from groups: alt.internet.wireless (More info?)

On Fri, 2 Jul 2004 19:44:57 +0000 (UTC), dold@ExternalXa.usenet.us.com
wrote:

>Jeff Liebermann <jeffl@comix.santa-cruz.ca.us> wrote:
>> The nice part is that it doesn't require an pigtails. A USB radio
>> should work as well. I'll leave it to your ingenuity to figure out
>> how to do it with a PCMCIA card in a laptop. (ribbon cable
>> extension?)

>I used a reflector with an Orinoco PCMCIA card.
>I was holding the reflector with one hand, and the laptop with the other,
>so it wasn't very useful, but NetStumbler definitely showed the effects of
>the reflector being in place.

Careful. Tuning by signal strength alone is not sufficient. You need
to keep an eye on the S/N (signal to noise) ratio. You can have a
very strong signal, but if multipath, reflections, or interference get
in the way, your S/N ratio and thus your thruput will suffer.

>"I'll leave it to your ingenuity to figure out how to do it" in some
>worthwhile fashion ;-)

The Orinoco/Proxim/Wavelan/Agere/Avaya/Whatever card has a connector
for a pigtail to an external antenna. Methinks that will work better
although it is admittedly more expensive.

--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831.336.2558 voice http://www.LearnByDestroying.com
# jeffl@comix.santa-cruz.ca.us
# 831.421.6491 digital_pager jeffl@cruzio.com AE6KS

Archived from groups: alt.internet.wireless (More info?)

On Fri, 2 Jul 2004 19:54:45 +0000 (UTC), dold@ExternalXa.usenet.us.com
wrote:

>Although Jeff might point out that all of my attempts are so haphazard,
>a few inches of length might not be important.
>Clarence A Dold - Hidden Valley (Lake County) CA USA 38.8-122.5

Yep. Let's do the math the long way (to illustrate the problem).

The 2.4GHz band is 83MHz wide.
One wavelength at the bottom of the band is:
3x10^8 meters/sec / 2.400x10^9 cycles/sec = 12.50 cm/wavelenth.
and at the top of the band:
3x10^8 meters/sec / 2.483x10^9 cycles/sec = 12.08 cm/wavelenth.
For a half wave dipole, the difference between the top and bottom of
the band is:
6.25 cm - 6.04 cm = 0.21 cm = 2.1 mm.
So, your basic tolerance for a simple (62mm) half wave dipole is plus
or minus 1.0 mm or your antenna falls out of the ISM band. Actually,
it's somewhat tighter than that as being 1.0mm off is sufficient to
screw up the VSWR and induce some entertaining group delay across the
operating bandwidth.

To be fair, the reflector does not need to be that accurate. Rule of
thumb for big dishes is flat within 1/10 wavelength or within 12.5mm
of flat at 2.4GHz. Well, ok... I guess your wrinkled aluminium foil
reflector is close enough.

--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831.336.2558 voice http://www.LearnByDestroying.com
# jeffl@comix.santa-cruz.ca.us
# 831.421.6491 digital_pager jeffl@cruzio.com AE6KS

Archived from groups: alt.internet.wireless (More info?)

Jeff Liebermann <jeffl@comix.santa-cruz.ca.us> wrote:
> Careful. Tuning by signal strength alone is not sufficient. You need
> to keep an eye on the S/N (signal to noise) ratio. You can have a
> very strong signal, but if multipath, reflections, or interference get
> in the way, your S/N ratio and thus your thruput will suffer.

The NetStumbler screen combines strength and SNR in one graph. There are
occasions where the "red" portion gets a little larger, but I live in the
sticks with no alternate sources of noise. The noise is generally -100dB,
so the SNR is pretty good. I do see it come up, but the best signal
strength is the lowest SNR in coincidence. I haven't tested throughput as
a tuning aid. I think that might be valuable with finely focused antennas
at long distance. Maybe I'll do a little checking with iperf.

> The Orinoco/Proxim/Wavelan/Agere/Avaya/Whatever card has a connector
> for a pigtail to an external antenna. Methinks that will work better
> although it is admittedly more expensive.

I have a few of those. A mag mount for the car, a Conifer that provides a
claimed 11dBi, and a spare "N" adapter that's not being used currently.

Flat pieces of metal are flat pieces of metal. I don't see the difference
in a commercially built antenna and a similar design built at home out of
Radio Shack PC board material. The commercial antenna might be built of
better material for outdoor use, or have plastic housings to make it look
pretty, but the dimensions are all that matter.

My wrinkled aluminum foil works as well as the Conifer, except that the
beam is narrower. I haven't looked at the specs to see if that is supposed
to be true. I started to learnbydestroying to measure the dimensions of
the Conifer, but I couldn't get myself to break the waterproof seal.

The only specs I can find for the Conifer are in Russian.

< http://www.rahul.net/dold/clarence [...] rength.htm >
< http://www.is.net.ua/wireless/prod/dl2410.html >
< http://dast.nlanr.net/Projects/Iperf/ >

--
---
Clarence A Dold - Hidden Valley (Lake County) CA USA 38.8-122.5