[CLUE-Tech] wireless ethernet industrial application

[Jim Ockers]

Hi everyone,

I thought I'd ask the group since I don't know what to do.  I
have a requirement to develop a prototype industrial-strength
communications system using COTS* hardware and WLAN.

Since nobody makes cheap, widely available frequency hopping
spread spectrum (FHSS) wireless ethernet cards, I think I'm 
going to have to use direct-sequence spread spectrum (DSSS) 
cards.  My major requirement is immunity to (or tolerance of) 
interference.  Reliability is king.

Linux support is obviously a requirement.  I thought I would use
an Intersil prism2 card but as of 3 or 4 months ago you can't
buy those in any quantity from any vendor.  They are GONE out of
the channel.  I have to use something that's readily available in
quantity.

So, what should I get?  I thought I would use the Atheros chipset
but the madwifi README says in the known problems section
"Performance in lossy environments is suboptimal."  Also madwifi
is beta, and might have a bunch of unknown problems.  The
industrial environment that this system will live in is very
"lossy."

I believe that Intel Centrino and any Texas Instruments chips are
out of the question due to lack of Linux driver support.

We don't need super speed (I'm replacing a 115Kbps link) - 
anything 1Mbps or faster would work.  Also, 2.4GHz is preferable 
to 5GHz because the range is slightly better with the lower 
frequency.

This is quite a bit different than trying to network a laptop
and a PC together in an apartment, and I'm not even sure how to
evaluate the WLAN hardware that's out there.

Any ideas?  Suggestions?  What is the best (newer) chipset to 
use?

Thanks,
Jim

PS COTS == Commodity Off The Shelf, in case someone didn't know.

PPS We might be able to get away with using any old WLAN card
if we had an antenna array and phased-array signal processing
hardware.  If I had a Ph.D. in computer science and another Ph.D.
in electrical engineering I might think about working on that.
I don't think there is a SourceForge open source phased-array
signal processing software package that I can download...

-- 
Jim Ockers, P.Eng. (ockers at ockers.net)
Contact info: please see http://www.ockers.net/