Incorrect Atheros txpower output

Sam Leffler sam at freebsd.org
Tue Jul 29 20:39:42 UTC 2008


M. Warner Losh wrote:
> In message: <6fe7c62a0807291226x15ef59bcn334c97562f3399b8 at mail.gmail.com>
>             "Mohammad Ikram" <ikram at wideband.com.pk> writes:
> : Hi !
> : 
> : I am using FreeBSD 7.0 and recently installed a Engines EPI-3601S card. The
> : card has an Atheros chip with a 27dBm output power rating. I am using it as
> : hostap. FreeBSD detects it fine, but the trouble is FreeBSD does not takes
> : the power level up. The max i was able to set is was 16dBm. (ifconfig ath0
> : txpower xx). I tried it on linux with madwifi but same results, so i started
> : having a few doubts with this card, a friend of mine suggested that i should
> : try the router OS (www.mikrotik.com) i did, and it worked perfectly.
> : 
> : can any one tell me why can't i change the power level ? (i did changed
> : country codes, to no avail)  i read some where it is the problem with the
> : driver ? so is there any patch ?
>
> Did you measure the output power directly?  Many cards have a final
> stage amplifier that kicks things up a few dB...  Maybe router OS
> knows about this card's quirks and copes...
>
>   

The external PA's you're thinking of are not controllable by the host; 
they are always present.  The original post doesn't explain how mikrotik 
"worked perfectly" while freebsd did not.  I have measured many high 
power cards with a power meter and SA under FreeBSD and have never seen 
a power cap other than that imposed by regulatory or vendor mis-claims.

    Sam



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