Felix Hi, Felix Domke wrote: > 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 The QPSK modulator block diagram as described here on page 6 http://web.syr.edu/~syu05/report%20for%20software%20radio.pdf can be helpful. Suppose the broadcaster does some stupid thing. eventually there is no separate I and Q signal for inversion to happen. Now, there are two places where this can happen, afaict. * LNB LO for by the down conversion mixer * Tuner I and Q inputs wired in an inverted way. Manu _______________________________________________ linux-dvb mailing list linux-dvb@xxxxxxxxxxx http://www.linuxtv.org/cgi-bin/mailman/listinfo/linux-dvb
