Hi, >>>>>> - Inversion might happen on up- and downconversion, depending on what >>>>>> frequency situation you have. >>>>>> - The SatelliteDeliverySystemDescriptor does not specify Inversion. >>>>> AFAICS, Inversion isn't a part of the transport. >>>> Why not? It's part of it like the frequency, isn't it? >>> What i meant is that it does not depend on the transport, but the hardware. >>> LNB + tuner <-> demod wiring >>> Whereas frequency is not. >> Some transponders have an inversed frequency spectrum already when >> broadcasted (before downconversion). >> There is no way for the broadcaster to specify this. > What do you mean by a inverted spectrum when broadcast ? > AFAICS, Inversion happens after there is a Phase shift to extract the I and Q signals Swapping I/Q is *one* way to create spectral inversion. Just inverting the spectrum is (obviosly) another one, and can happen on the (non-complex) modulated signal as well. Just mix it with another frequency and take the lower sideband. It's the same thing which happens in a C-Band downconversion - it can also happen in the upconversion. I don't know if broadcasters are required to send non-inverted signals. I just know (read: remember) that some do. I might be wrong, so second opinions are welcome. Again, I'm not a frontend guy. Maybe somebody with broadcasting experiences can tell us more here. Felix _______________________________________________ linux-dvb mailing list linux-dvb@xxxxxxxxxxx http://www.linuxtv.org/cgi-bin/mailman/listinfo/linux-dvb
