Re: [RFCv2] Add spectral scan support for Atheros AR92xx/AR93xx

[Simon Wunderlich <simon.wunderlich@s2003.tu-chemnitz.de>]

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Hello Adrian,

On Sun, Dec 30, 2012 at 11:48:36PM -0800, Adrian Chadd wrote:
> Hi all,
> 
> Simon - I've reviewed your code a bit.

Cool, thanks a lot! Since you are replying to v2, I hope you are
aware that I posted a v3 version[1] already?

[1] http://thread.gmane.org/gmane.linux.kernel.wireless.general/101735
> 
> You're not (yet) shifting the magnitude values over as needed before
> trying to extract the channel power out of it all.
> 
> Specifically:
> 
> * each bin has a 7 bit value;
> * the bin value is scaled by max_exp;
> * there's a max magnitude value which I don't think you need for
> spectral FFT reports; only radar FFT reports (since in radar FFT
> reports, the reported FFT bins are between 0..7/8ths of the maximum
> magnitude value)
> 
> You're not scaling the data by max_exp in your FFT dump program, so
> the values aren't entirely correct.
> Are you doing it in the kernel code?

In the latest patchset I'm doing scaling already in the kernel driver.
I haven't done this in the v2 patchset yet, something for scaling
was included in the then-corresponding FFT dump program. As I'm using
the new format now with the pre-processed and scaled dumps from the
kernel, this code has been removed in my FFT dump program. :)

> 
> I've just finished my first pass at this and plotting whatever values
> I get from the spectral data frames. I'll post more updates as I
> find/fix more bugs.

Cool! What kind of tool do you use for plotting? Maybe we can use
something (my simple program, yours, whatever) for both Linux and
FreeBSD? 

Thanks as always for the feedback!

Cheers,
	Simon

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