Re: Turning up the power? (experimental patch)

From: Hristo Nazarow (
Date: 2002-01-03 17:40:50 UTC

Hi there,
Happy New Year,
I have some prism2 PLX cards and I can not use this driver:::(((. My question is would be enough to hack CR31 (card PDA) with prism2dl (linux-wlan), And increase TX Power?
>There is a test command to set automatic level control (ALC)
off. I haven't measured TX power changes, but at least this allowed the driver to control CR31.

Do i need to disable ALC, I know that latest wlan-ng supports wireless extensions?
Hristo Nazarov

> On Tue, Jan 01, 2002 at 11:24:06AM +0200, Jouni Malinen wrote:
> > I do not know the proper mapping of TX power between dBm/mW and CR31,
> > but this patch uses the mapping proposed in WAP11 related
> > text. iwconfig can be used to set TX power with 'txpower' command
> > (check 'man iwconfig'). Current version of the driver uses this
> > assumed mapping and the power levels may be totally off. I'll take a
> > closer look at this, but please let me know, if you happen to
> > know/figure out proper mapping.
> Good news: manual TX power setting seems to works. Bad news: the above
> mentioned guess about the mapping is incorrect (at least on all
> cards I tested). Apparently it would be better to prefer data sheets over
> web pages describing AP hacking ;-). CR31 is signed 7-bit value (lowest
> ignored). -64 results in highest TX power and 63 in lowest, but I'm not
> whether this is linear or logarithmic (or something else).
> Receiving station (Lucent WaveLAN, couple of meters from AP) reported
> levels from -40 dBm to -100 dBm and the reported value seemed to
> quit nicely to the configured CR31 value. The default TX power level
> (automatically controlled by the MAC) seemed to be quite close to the
> maximum TX power, so turning up the power is quite limited. However, it
> possible to use much smaller TX power so this might be especially useful
> environments that have the AP near and do not which to flood the
> neighborhood with unwanted signals.
> In other words, the patch I sent does not work correctly when TX power is
> set with iwconfig's txpower command, but the TX power can be set with
> lower-level access (iwpriv wlan0 alc 0; iwpriv wlan0 txpower ###). This
> unsigned integers, so 128 corresponds to maximum TX power and 127 to
> (from lowest to highest power: 127..0, 255..128). I'll modify SIOCSIWTXPOW
> to use a bit more intelligent mapping so that iwconfig can be used to set
> the power levels. The values won't probably match exactly with the TX
> level, but at least the lowest and highest level should be in the correct
> ends of the scale ;-).
> --
> Jouni Malinen PGP id EFC895FA

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