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Date:      Wed, 6 Dec 2000 10:53:06 -0700 (MST)
From:      Nate Williams <nate@yogotech.com>
To:        Warner Losh <imp@village.org>
Cc:        Christopher Yeoh <cyeoh@linuxcare.com.au>, Greg Lehey <grog@lemis.com>, Wesley Morgan <morganw@chemicals.tacorp.com>, mobile@FreeBSD.ORG
Subject:   Re: ray committed 
Message-ID:  <14894.32002.562845.683899@nomad.yogotech.com>
In-Reply-To: <200012060604.XAA76044@harmony.village.org>
References:  <14893.53324.616401.949125@rockhopper.linuxcare.com.au> <20001206152332.A21187@wantadilla.lemis.com> <Pine.BSF.4.21.0011122152410.34677-100000@volatile.chemicals.tacorp.com> <200011130313.UAA03395@harmony.village.org> <200012060509.WAA75737@harmony.village.org> <20001206154244.J20481@wantadilla.lemis.com> <200012060604.XAA76044@harmony.village.org>

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[ Orinoco vs. Zoom card experience ]

> I could then take the laptop with the aviator upstairs to 1' of the
> base station (which is just an intel box with an aviator card) and get
> 0 throughput (which sounds like a driver problem).  The really strange
> part is that I can reboot both machines and still get horrible to zero
> throughput.  This points to "enemy action" of some sort.

Are these radios 'Air' compatible with one another?  If not, one may be
using Spread Spectrum, and the other Frequency Hopping.

In some experience I've experienced in my 'Day Job', the Spread Spectrum
cards (Orinoco/WaveLan and clones) are *MUCH* (!!!) less suceptible to
noise than the cards based on hopping technology.  (802.11 allows for
both).

As a point of fact, my employer uses FH radios in their product, and my
ISP uses the Wavelan stuff.  Interestingly enough I had to shield my
employer's product from the Wavelan stuff even though the Wavelan
products are pushing a mile between sites.  I would have assumed that
the Wavelan cards would have the more difficult time because of the
link-length losses, but the opposite is true.  The Wavelan cards seems
to be completely un-affected by the FH card noise, while the FH cards
are wiped out by the SS cards.

> I also have a wireless link with the older pre802.11 wavelan cards at
> 2.4GHz to a friends house.  Maybe that is impacting things.  It
> doesn't impact the 802.11b cards that I use.

In my experience, the old 'non-802.11' cards seem to be less effected by
noise than the newer cards, FWIW.

Finally, multi-path can really screw you up when you get the radios
close to one another.  In our product, we have to use attenuators to get
decent performance when the radios are close to one another.


Nate



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