On 09/15/2016 08:28 AM, Zefir Kurtisi wrote:
Hi Ben,
On 09/15/2016 02:22 AM, Ben Greear wrote:
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.
Whew, that year went by so incredibly fast ;)
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.
Yes, that's essentially it - the last step is even not needed if your goal is to
estimate DFS detection probabilities, since in the certification lab they usually
just repeatedly fire the radar pattern and count detection events.
When I played with the modified carl9170 FW, I estimated that developing an solid
and reliable radar pattern pulse scheduler would take me 2-4 weeks, so being in a
hurry I ended up using an SDR (Ettus USRP N200, see [1]). I developed a pulse
scheduler to feed arbitrary patterns (covering those for DFS testing), which is
available in [2]. It has not been maintained ever since, but might help you as
starting point if you decide to go that route.
Out of curiosity, about how much did that kit cost?
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
We use the R&S SMBV100A [3], which we know is also used in some certification
labs. Unfortunately it is not exactly cheap - if you are not going to prepare your
product for certification, the SDR approach is affordable and good enough.
Thanks for the info. We previously used the carl9170 to do some const-tx signal generation
to reproduce some interesting crashes in ath10k, and now a user wants a cheap radar emulator.
We could also use it for some basic testing in our own labs.
I'll work on allowing the specific number of pulses as well as a quiet period in
the carl9170. Hopefully just a day or two of work on top of what I already have.
Thanks much for the suggestions.
--Ben
Thanks,
Ben
Good luck,
Zefir
[1] https://www.ettus.com/product/details/UN200-KIT
[2] https://github.com/zefir-kurtisi/USRP-Radar-Relay
[3]
https://www.rohde-schwarz.com/us/product/smbv100a-productstartpage_63493-10220.html
--
Ben Greear <greearb@xxxxxxxxxxxxxxx>
Candela Technologies Inc http://www.candelatech.com
