Thanks very much for the help! I obtained the book (fifth edition) and already read whole section 2.1 (Band pass and Low pass Signals). That was exactly what I was looking for.
I have one more doubt. Figure 2.1-6 in page 25 shows a real demodulator (I attached the figure here). This is not the same block diagram of the demodulador that we have inside Elonics E4000 Tuner (zero-IF demodulador). We don't have a Hilbert transformer inside the zero-IF demodulator. We have just two paths, one multiplying by cos() and the other by sin(). Perhaps the Hilbert transform is implemented by handling the I and Q components as a complex number I+jQ inside GNU Radio? Can someone please explain to me how the zero-IF demodulator is related to the real demodulator shown in the book? Thanks very much again, Lucas Lorenzi Ingles 2013/9/30 Aditya Dhananjay <adi...@cs.nyu.edu> > Perhaps, Chapter 2 of "Digital Communications" by John Proakis? > > best, > aditya > > > > On Mon, Sep 30, 2013 at 10:26 AM, Lucas Ingles <lucas.lore...@gmail.com>wrote: > >> Hello to all, >> >> I am using GNU Radio to study digital communications systems. >> I have been working on the basic FM receiver with RTL-SDR for a while. >> >> I was trying to find out what is the theory behind the complex I/Q >> samples. >> What I discovered is that I/Q samples are first related to analytic >> signals (the pre envelope) and then to the complex envelope of the signal >> (the complex signal in base band). >> In fact, what RTL-SDR outputs to the flow graph is the complex base >> band signal, in other words, the signal translated to base band with just >> the positive or negative portion of the spectrum. >> >> Please, can someone with more experience confirm to me if I am correct? >> Can someone please recommend me some reference books about the theory of >> I/Q samples? >> >> Thanks very much in advance, >> Lucas Lorenzi Ingles >> >> _______________________________________________ >> Discuss-gnuradio mailing list >> Discuss-gnuradio@gnu.org >> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >> >> >
<<attachment: demodulator_proakis.jpeg>>
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