[ath9k-devel] ath9k: spectral scan -vs- channel state information

Robert Felten <robert.felten <at> googlemail.com> writes:

> 
> Hi Allen,
> 
> Spectral scan sum up I and Q for you and give you the magnitude it.
> Since I and Q are "merged", no phase information is available.
> As Adrian said, you have to run some math to get power in dBm from the
> special spectral sample format.
> If you are able to read Python code, here is an example for the transformation:
> https://github.com/bcopeland/speccy/blob/master/spectrum_file.py#L57
> 
> If you prefer "real code", there is an implementation how to threat
> the sample data in Adrians Radarlib:
> https://github.com/erikarn/ath_radar_stuff/tree/master/lib/libradarpkt
> 
> The paper found on "Atheros CSI Tool" link states:
> "The CSI measurements are complex values and hence contain two parts,
> the amplitude and the phase."
> So I guess that with CSI the I and Q values aren't merged. If you do
> so, you should be able to calculate the power levels - then you should
> end up with the same information like from spectral scan.
> But I do not have any first hand experience with CSI, if you have any,
> please share :)
> 
> If you want to play around with the spectral scan feature, I recommend
> to to give Bob Copelands "Speccy" a try:
> https://github.com/bcopeland/speccy
> 
> Hope this helps.
> 
> Robert
> 
> 2016-05-09 3:42 GMT+02:00 Allen Welkie <allen.welkie <at> gmail.com>:
> > Adrian Chadd <adrian <at> freebsd.org> writes:
> >
> >
> >>
> >> Well, there's magnitude and phase, and it gives you the values for
> >> each. You have to run it through math to get a power level for each
> >> bucket.
> >>
> >> https://wiki.freebsd.org/dev/ath_hal%284%29/SpectralScan
> >>
> >> You don't get separate readings for I and Q in spectral scan data.
> >>
> >> -adrian
> >>
> >
> > I'm confused. You say that the spectral scan only gives the magnitude of the
> > I and Q values combined, not separate. But then you say that "there's
> > magnitude and phase, and it gives you the values for each." Doesn't that
> > mean that you do get both the I and Q values (after converting from
> > magnitude/phase values)?
> >
> > Also, is this the same info that's logged in the "Atheros CSI Tool"
> > (https://github.com/xieyaxiongfly/Atheros-CSI-Tool)? Or is the spectral scan
> > data completely different?
> >
> > _______________________________________________
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> > ath9k-devel <at> lists.ath9k.org
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> 


Hi Folks

I have been using both Spectral and CSI.