[prev in list] [next in list] [prev in thread] [next in thread]
List: gnuradio-discuss
Subject: Re: [Discuss-gnuradio] I/Q samples and Analytic Signals
From: Lucas Ingles <lucas.lorenzi () gmail ! com>
Date: 2013-09-30 19:15:30
Message-ID: CAHA_kS39zAv9fDRtRSX7Eod1ufu0iCOakK5Q90B6s=Xn=SL9HA () mail ! gmail ! com
[Download RAW message or body]
[Attachment #2 (multipart/alternative)]
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 <aditya@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.lorenzi@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 #5 (text/html)]
<div dir="ltr">Thanks very much for the help!<div style>I obtained the book (fifth \
edition) and already read whole section 2.1 (Band pass and Low pass \
Signals).</div><div style>That was exactly what I was looking for.</div> <div \
style><br></div><div style>I have one more doubt. Figure 2.1-6 in page 25 shows a \
real demodulator (I attached the figure here).</div><div style>This is not the same \
block diagram of the demodulador that we have inside Elonics E4000 Tuner (zero-IF \
demodulador).</div> <div style>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().</div><div style>Perhaps the Hilbert transform is implemented by handling \
the I and Q components as a complex number I+jQ inside GNU Radio?</div> <div \
style>Can someone please explain to me how the zero-IF demodulator is related to the \
real demodulator shown in the book?</div><div style><br></div><div style>Thanks very \
much again,</div><div style>Lucas Lorenzi Ingles</div> <div style><br></div><div \
style><br></div><div class="gmail_extra"><br><br><div class="gmail_quote">2013/9/30 \
Aditya Dhananjay <span dir="ltr"><<a href="mailto:aditya@cs.nyu.edu" \
target="_blank">aditya@cs.nyu.edu</a>></span><br> <blockquote class="gmail_quote" \
style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div \
dir="ltr"><div style="font-family:courier new,monospace">Perhaps, Chapter 2 of \
"Digital Communications" by John Proakis?</div> <div \
style="font-family:courier new,monospace">
<br></div><div style="font-family:courier new,monospace">best,</div><div \
style="font-family:courier new,monospace">aditya</div><div style="font-family:courier \
new,monospace">
<br></div></div><div class="gmail_extra"><br><br><div class="gmail_quote"><div><div \
class="h5">On Mon, Sep 30, 2013 at 10:26 AM, Lucas Ingles <span dir="ltr"><<a \
href="mailto:lucas.lorenzi@gmail.com" \
target="_blank">lucas.lorenzi@gmail.com</a>></span> wrote:<br>
</div></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px \
#ccc solid;padding-left:1ex"><div><div class="h5"><div dir="ltr">Hello to \
all,<div><br></div><div>I am using GNU Radio to study digital communications \
systems.</div> <div>
I have been working on the basic FM receiver with RTL-SDR for a \
while.</div><div><br></div><div> I was trying to find out what is the theory behind \
the complex I/Q samples.</div><div>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).</div>
<div>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.</div><div><br> </div><div>Please, can someone with more \
experience confirm to me if I am correct?</div><div>Can someone please recommend me \
some reference books about the theory of I/Q samples?<br></div><div><br></div> \
<div><div>Thanks very much in advance,</div>Lucas Lorenzi Ingles </div></div>
<br></div></div>_______________________________________________<br>
Discuss-gnuradio mailing list<br>
<a href="mailto:Discuss-gnuradio@gnu.org" \
target="_blank">Discuss-gnuradio@gnu.org</a><br> <a \
href="https://lists.gnu.org/mailman/listinfo/discuss-gnuradio" \
target="_blank">https://lists.gnu.org/mailman/listinfo/discuss-gnuradio</a><br> \
<br></blockquote></div><br></div> </blockquote></div><br></div></div>
--047d7b15a72bd7193c04e79ea85b--
["demodulator_proakis.jpeg" (image/jpeg)]
[prev in list] [next in list] [prev in thread] [next in thread]
Configure |
About |
News |
Add a list |
Sponsored by KoreLogic