On Thu, Feb 15, 2018 at 07:51:28AM +0200, Kalle Valo wrote:
> James Cameron <qu...@laptop.org> writes:
> 
> > On Wed, Feb 14, 2018 at 04:26:42PM +0000, Jean Pierre TOSONI wrote:
> >> ath9k returns a wrong RSSI value for frames received in a 30ms time
> >> window after a channel change. The correct value is typically 10dB
> >> below the returned value.
> >
> > How was your correct value determined?
> >
> >> This was found with a Atheros AR9300 Rev:3 chip (WLE350NX / JWX6083
> >> cards), during offchannel scans.
> >> 
> >> Mark the signal value as invalid in this case.
> >
> > Why not adjust by 10dB?
> >
> > Speculating: in a typical card, RSSI is calculated by firmware from
> > readings of ADCs attached to the receiver.  Firmware may average
> > several readings.  Firmware may apply other offsets or calibrations,
> > based on frequency and temperature.  This sounds like a firmware
> > problem.
> 
> ath9k does not have firmware, only ath9k_htc has it.

Heh.  s/firmware/silicon implementation/g

-- 
James Cameron
http://quozl.netrek.org/

Reply via email to