SR71-A Txpower Question

[Adrian Chadd]

Hi,

ifconfig wlan0 txpower 0 merely sets the txpower to 0dBm, which isn't
"off" strictly speaking. It's actually 1mW.

The SR-71A also has a TX power offset in hardware. If I remember
right, the hardware is actually a couple of dBm higher than what you
configure. So when you configure 19 dBm, you're programming the
hardware at 19dBm, but the hardware responds by allowing a max of
16dBm per channel, which is * 3 (3 TX chains, as per the patch I gave
you) to give ~ 21dBm. I'd have to check the math to get the exact tx
power offset but that's roughly what's going on.

Now, if it's documented somewhere that 0 dBm should be "killing" the
interface, let me know. :)



Adrian

On 25 May 2011 00:24, Shant Kassardjian <shant at skylab.ca> wrote:
>
> Hello FreeBSD-Wireless,
>
> I've been running SR71-A on FreeBSD 8.1 for quite some time now and it's been running very well. Many thanks to Adrian Chadd who really helped ironing out all my questions!
>
> My only problem so far that I've noticed is that when I do:  ifconfig wlan0 txpower 0; this does not turn off power to the wireless as it's suppose to and rather I have to bring down the interface manually to shut it down hence whenever I need to start it up again I have to reconfigure the interface.
>
> >From my observation it looks like changing the txpower rate using ifconfig has little to no effect controlling this adapter.
>
>
> My question is that, could it be because I have compiled the kernel with the following modifications as suggested by Adrian Chadd to take advantage of Max 3x antenna transmit power that I am having this problem?
>
> Edit sys/dev/ath/ath_hal/ar5416/ar5416.h:
>
> #define AR5416_DEFAULT_RXCHAINMASK      7
> #define AR5416_DEFAULT_TXCHAINMASK      7
>
>
> Does anyone else have this symptom with their SR71-A (AR5416)?
>
>
> Many thanks in advance;
>
> Regards,
> Shant K.
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