Subject: Re: driver for webgear aviator 2.4 card
To: None <tech-kern@netbsd.org>
From: Mike Cheponis <mac@Wireless.Com>
List: tech-kern
Date: 01/24/2000 11:13:24
On Mon, 24 Jan 2000, Lennart Augustsson wrote:

> Thor Lancelot Simon wrote:

> > Please excuse this question from someone very naive about 802.11:
> >
> > Will these cards talk to _any_ other 802.11 cards?  If so, which ones?
> 
> The 802.11 standard is another one of those standards that is the union
> of several things.  It encompasses two totally incompatible modulation
> methods: slow frequency hopping and CDMA (or direct sequence as it's called
n> in 802.11).  With the same modulation type and data rate I think the
> theory is that different cards should be able to talk to each other, but
> I wouldn't bet on it.

Normally, Frequency Hopping (FH) and Direct Sequence (DS) types of Spread
Spectrum are both called "CDMA" - so much so that "Code Division, Multiple
Access" essentially means "Spread Spectrum" these days.


> > My dad's just dropped the dough for an AirPort Base Station and the card
> > for his iBook -- I'd love to find cheap ISA cards I could use to clean
> > up the rest of the cable mess all over his house.
> 
> AirPort uses direct sequence, so Aviator cards can't talk to them.

That's right.

There are pretty much two competing standards: 2 Mb/s DS from Lucent and
FH from everybody else.  

Here's an excellent page from Breezecom that helps explain the differences:

<http://www.breezecom.com/TechSupport/fhvsds.htm>


For more generic Spread Spectrum, see <http://www.sss-mag.com/>


Incidentally, FHSS was invented and patented during WWII by Hedy Lamarr,
an actress, who died only last week.  See

<http://www.hoxie.org/news99/senior99/hedy1.html>


-Mike Cheponis
mac@wireless.com