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From: navprojects on 20 Feb 2006 19:00
Hi Jeff,

My apologies for the delay in responding with followup.
As mentioned in the last posting I was looking into various aspects of this
question and also on some of the information which came from your links.

> The Sputnik spreadsheet claims to calculate range for their products.
> http://www.sputnik.com/support/docs/docs_deployment.html
> I don't know how accurate it is becauase I haven't played with their
> equipment.

> >Great, I also had seen a couple of these (Cisco etc), but the others are
> >very appropriate.

I looked at this, there is little help on the interpretation of the optional
sheet's cells. The PDF is compensates a little.

> I have some issues with the Proxim spreadsheet, which uses 12dB as the
> target fade margin, and the Cisco spreadsheet, which uses 10dB.
> 10-12dB is barely functional and not very reliable. I deal with one
> 5.6GHz link with a 13dB caculated fade margin. (The aesthetics
> committee would not allow larger dish antennas.) It's down about 10%
> of the time, which is acceptable because all it does is unload
> non-time sensitive collected data.

> >In fact it's interesting to note that 'expected range' calcs based on
> >specsheet data are hard to come by. It might be nice to devise one.
> >Based on your approach above it should not be difficult.

> Yet another project. However, it's something I find interesting.
> However, I will NOT concoct a fixed table or chart showing "typical"
> speeds and ranges. There are far too many variations and I don't
> wanna spend my life defending the numbers.

> >> I'll post the material attenuation specs when www.thirdbreak.org comes
> >> back online.

Looked at it briefly but I had already read these notes of yours with
pleasure.
Sputnik Firmware for Linksys WRT54GL ?
AFAYK they write FW's for other Linksys products? (Not mentioned there.)

> The site is back up. No clue what happened (or why it only happens
> when I post a link to it). Probabaly a conspiracy.
> http://www.thirdbreak.org/pipermail/wireless/2005-June/000804.html
> Note that the material attenuation numbers are all over the place and
> vary with the source. I once read a report where an instructor had
> students measure wall, door, and window attenuation. The result was
> huge variations in attenuations. I was also amused at reading the
> table of attenuations "accurate" to 3 decimal places. Sigh.
>
> I've also had some entertainment dealing with people that claim they
> have perfectly good coverage going through 4 or 5 walls. It's
> possible, but more often, the signal arrives via a reflection through
> open windows that simply bypass the walls. I got involved in such a
> mystery when a company was doing a site survey and noticed that the
> signal was useable no matter how many walls they went through. When I
> showed up, I blocked a few windows with aluminum foil and wall
> attentuation returned to normal. In another, it was leaking through
> the HVAC ducts. Still another leaked trough the plenum above a
> suspended acoustic ceiling. Translation: It's REALLY difficult to
> get accurate material attenuation numbers as much depends on the
> layout.

Interesting story :-)

> Testing Wireless Products:
> http://cpliterature.product.agilent.com/litweb/pdf/5988-3762EN.pdf
>
> >A site that might interest you is the following which offers a reasonably
> >sophisicated Survey Tool for an acceptable price.
> >http://www.ekahau.com/?id=4600
>
> Ekahau is $6,000. Also see:
> http://www.airespace.com/products/appnote_wlan_planning_design.php
> Airespace is now owned by Cisco.

Hey Jeff, you might be mistaken here. I have found several quotes going from
3,500 ca. down. It all depends on which packet you buy. The developpers kit
is over 5,000 but the basic Survey is much less.
In professional circuits it is quoted as being a good product.
In case your interested in an excellent comparison review of Wlan tools :
http://www.networkcomputing.com/channels/wireless/showArticle.jhtml?articleI
D=174402549&pgno=1

I have seen it priced at less under $. 2,000 in some places.
Hope to get back with some other info on estimation/calculation/comparison.
If you have anything else let me know.
Thanks for the help.


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