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[Discuss-gnuradio] Re: new to GNU radio

From: jiqun qi
Subject: [Discuss-gnuradio] Re: new to GNU radio
Date: Tue, 4 Mar 2008 20:45:53 -0600


In fact, the mapped complex symbol will go into two parts, that is,
the real part and the image part will modulate the cos(w_c * t) and
sin(w_c * t), separately.
E.g., complex symbol is denoted, y = a+jb = r*cos(theta) + j*r*sin(theta);

so, a*cos(w_c * t) - b*sin(w_c *t)
= r*cos(theta)*cos(w_c * t) - j*r*sin(theta)*sin(w_c * t)
= r*cos(w_c * t + theta)

This is the final transmitted real signals, where w_c is the carrier
frequency, shown in Gnu radio as well.

>yup..got it..thanks..

>i understood in QPSK how the bits get mapped to constellation space.

>One doubt still persists.QPSK modulation theory tells us that we need to
>change the phase of the carrier depending upon the incoming data
>bits..i.e what we see mapped to the constellation space is the modulated
>I cannot see a carrier frequency specified anywhere in bqpsk.y..Where do
>i specify the carrier frequency for my transmission...this part is still
>a bit hazy...
>I can see the incoming bits getting mapped to constellation space not
>the modulated data..M i missing something here?

>Posted via http://www.ruby-forum.com/.



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