Subject: Re: Using ath5k/ath9k radio for constant-tx noise source.
To: Zefir Kurtisi <zefir.kurtisi@neratec.com>,
        "linux-wireless@vger.kernel.org" <linux-wireless@vger.kernel.org>
References: <55D4D406.5000603@candelatech.com> <55D5EE0E.3020408@neratec.com>
Cc: Christian Lamparter <chunkeey@googlemail.com>
From: Ben Greear <greearb@candelatech.com>
Message-ID: <6d50965d-af35-dad9-23fe-162678a0f02f@candelatech.com> (sfid-20160915_022251_825178_592A7601)
Date: Wed, 14 Sep 2016 17:22:46 -0700
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On 08/20/2015 08:11 AM, Zefir Kurtisi wrote:
> On 08/19/2015 09:07 PM, Ben Greear wrote:
>> I have a commercial AP that is using a CM9 ath5k radio (evidently, I could be wrong)
>> and it has the ability to do a constant transmit of raw noise (RF probe shows
>> noise, but a monitor-port sniffer does not see any frames from the CM9).
>>
>> I don't know the low-level details of how it is doing this, but I suspect
>> it is using something like madwifi for a driver.
>>
>> Does anyone know how this can be done with modern software and
>> ath5k or ath9k NICs?
>>
>> Thanks,
>> Ben
>>
>
> Maybe slightly related: some years ago when DFS became a topic and it was hard to
> get hands on radar pattern generators, Christian Lamparter wrote a variant of the
> carl9170 fw [1] which can generate radar pulses to test ath9k and other DFS radar
> detectors. Pulses are generated by enabling txout at defined sampling intervals.
>
> It should be doable to mimic what you are looking for by generating a _very_ long
> pulse.

Sorry to revive such an old thread..but I'm back poking at this.

I've used the modified carl9170 firmware to generate pulses, with
the control being 'pulse-width' and 'pulse-interval'.

This sort of works, and sometimes our ath10k in an isolation chamber reports
a radar event.

But, after some reading, I am thinking I need more control to better mimic
a radar.

If I understand things properly, I need something like this:

A pulse event being:  pulse width, pulse period:  For instance 1us, 200us
Then, I need to configure an amount of pulse events, maybe 10-30 consecutive pulse events.
Then, I need a quiet period to mimic the radar sweeping full circle (15 seconds perhaps)

 From what I can tell, the carl9170 modified firmware is missing the features
to do this, though it should not be too difficult to add.

If someone has an idea whether the control above is appropriate, I'd
appreciate feedback before I start hacking...

This document seemed useful, for instance:

https://dl.cdn-anritsu.com/en-en/test-measurement/files/Product-Introductions/Product-Introduction/mx370073a-el1200.pdf

Thanks,
Ben

-- 
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc  http://www.candelatech.com