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[Ham-80211] Access control suggestions

David Young dyoung at pobox.com
Thu Nov 4 20:01:46 UTC 2004

On Thu, Nov 04, 2004 at 11:34:31AM -0500, Guillaume Filion wrote:
> "Steven Phillips" <steven_phillips at yahoo.com> wrote:
> > Here's a thought.  How about we work with major
> > manufacturers such as Icom (who already has wifi
> > products), yaesue, kenwood, etc. to get them to
> > produce a ham radio specific WiFi solution.  The
> > technology would be identical to existing products.
> > Only difference would be is setting the RF equipment
> > to work on ham radio frequences that do not fall on
> > the shared part 15 frequencies.  If they contracted
> > with companies such as Orinoco, Linksys, Cisco and
> > other wifi producers, there would be very little
> > startup costs.  Just  a matter of firmware
> > modification (I think) to use ham specific frequences.
> >  If that could happen, then we would not have to worry
> > about the mixup between part 15 and part 97 users.
> >
> > IF they can do this for under $50, even under $100, I
> > could jump out and buy one.
> I read an interesting article (http://kerneltrap.org/node/view/4118) about
> adding support for most wireless cards to the open-source operating system
> OpenBSD.
> Here's the part of the article that sparked my interest:
> -----
> Jeremy Andrews: What exactly do you hope to accomplish with the wireless
> vendors, and how quickly?
> Theo de Raadt: Well, the four large vendors in the wireless space are
> currently Intel, TI, Conexant/Intersil (Prism G/Javelin) and Atheros. The
> first three need firmware. The Atheros does not require a firmware since it
> does not have a host cpu (instead: it requires a .o object blob of code that
> runs on the host machine, but reverse enginering for that is very nearly
> complete).
> -----
> If I'm not mistaken, that means that the reverse engineering of the Atheros
> "firmware" is almost complete.

It looks to me like the reverse-engineering has just begun.  Many "magic
numbers" (un-named numbers whose functional role is unclear) remain.

I don't know where Theo gets the idea that "the" four large vendors in
the space are Intel, TI, Conexant/Intersil, and Atheros.  Surely Broadcom
is in the top four?  And on most of the $10 802.11b cards you can buy,
there is usually a chip by Realtek or ADMtek.  And I thought that Conexant
was losing favor with OEMs.

I think that for amateur experimentation, the firmware-based radios may
be a dead-end, unless and until there are cheap/free development kits for
the on-board microcontrollers.  You need to re-program the microcontroller
if you're doing to meddle with the synthesizer settings and tune non-ISM
frequencies.  With the ADMtek / Realtek chips (and finally the Atheros
chips), you can program the transceiver/synthesizer/baseband chips
directly with software that runs on your PC.

Links to Realtek and ADMtek sources are below.  My Realtek driver is
not finished, yet.  Word is that the open-source Linux driver is finished.

ADMtek ADM8211

ADMtek ancillary chips: RFMD RF3000, Silicon Labs Si4136.

Realtek RTL8180

Realtek ancillary chips: Maxim MAX2820, Philips SA2400.


David Young             OJC Technologies
dyoung at ojctech.com      Urbana, IL * (217) 278-3933

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