SR71-A Txpower Question

[Adrian Chadd]

Hi!

No worries. I plan on digging up my previous emails with Ubiquiti and
documenting exactly what the SR-71A behaviour should be.

Thanks,


Adrian

On 26 May 2011 11:14, Shant Kassardjian <shant at skylab.ca> wrote:
>
> Hello Adrian,
>
> Glad to see you're always there for us!
>
> I spent countless hours looking for ubiquiti documentation that proves setting txpower 0 turns off the device...
>
> and found nothing so far. Either way, I still see this as a useful feature to consider :)
>
> Thanks for the detailed explanation regarding the txpower formula, it makes much more sense now whenever I play with the power transmit settings.
>
> Thanks again!
> Shant K
>
>> Date: Wed, 25 May 2011 00:43:21 +0800
>> Subject: Re: SR71-A Txpower Question
>> From: adrian at freebsd.org
>> To: shant at skylab.ca
>> CC: freebsd-wireless at freebsd.org
>>
>> 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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>> >
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