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[Ham-80211] Rw: 23cm transverters for 802.11>

Bob Keyes bob at sinister.com
Sun Oct 7 09:19:18 UTC 2007



On Sat, 6 Oct 2007, Steve wrote:

> What we've found is the tricky part is the switching times.  Which is why a
> lot of our work revolved around FHSS equipment.  It's just easier to work
> with.

I just had another idea on switching times: If we were able to get the
firmware to signal that it was going to start transmitting, and then delay
enough ns for the switch to kick in, that should solve the problem. Of
course, you have to be able to get down into the low-level functions of
the WiFi chipset in order to do that. In the past, this might not have
been so easy but the drivers for the Atheros chipset have been
reverse-engineered and a fully open-source driver been built, called
OpenHAL. This is already the default driver for OpenBSD and will shortly
be the Atheros driver for Linux. I know that the Atheros chipset relies
heavily on the host systems CPU, instead of having its own on-board
microcontroller like earlier radio cards, so I am pretty sure this is
possible. However, it still may take some doing to uncover exactly what
would need to be reprogrammed in order to accomplish this.

Another thing about the Atheros cards was one of the primary (purported)
impetus for having the driver closed-source in the first place was to
prevent people from going out of authorized bands. However, this dam has
already been burst, so to speak, as there is a value that can be placed
into the 'country code' register that will allow universal coverage, into
areas well outside the Part 15 bands. So far, there have been no reports
of the feared hoards of 'free channel' modern-day version of the CB
hackers of old causing widespread chaos. In any case, this should allow
hams to take full advantage of WiFi gear for 2.4 ghz operation, and also
allow us more flexibility when using transverters.





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