[linux-dvb] Circular polarization
dubost at crans.ens-cachan.fr
Fri Mar 31 19:50:11 CEST 2006
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Gregor Fuis wrote:
> I am using Nexus-S card and i would like to know if latest hq v4l-dvb
> driver support circular polarization. And if so, do i need support for
> that polarization in my application with which i watch dvb-s programs.
> The reason is that i got a subscription fot N-TV channels on Eutelsat 4W
> and i am planing to tur the dish there if it works.
A little physics about this ...
If the light is in linear polarization, you'll get a number of photons
proportional to cos2(theta) where theta is the angle beetween the
polarization of the photons and your linear polarizer.
Now if you put photons with a circular polarization on a linear
polarizer you'll ALWAYS get one photon about two (in average).
In regular cards there is (in general) two orthogonal linear polarizers.
So you can try with any linear polarization but you'll get -3dB on your
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