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From: | Martin Dvh |
Subject: | Re: [Discuss-gnuradio] gnuradio 101 |
Date: | Tue, 23 Aug 2005 17:46:01 +0200 |
User-agent: | Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.5b) Gecko/20030823 |
cswiger wrote:
One thing I don't understand tho: if a typical mux of 0xF0F0F0F0 feeds zeros to all DDC Q inputs, and ADC 0 to all DDC I inputs, nchannels = 1 sends data from DDC 0 only, and looking at the DDC block diagram in figure 3 at: http://www.gnu.org/software/gnuradio/doc/exploring-gnuradio.html how is it we can a complex stream to the software? Why aren't all the Q values also 0 ( zero * nco-cos ) ? Is the decimating low pass filter also a hilbert?
I think simple complex math: out.complex=ADC.complex * NCO.complex out.real=ADC.real*NCO.real - ADC.imag*NCO.imag out.imag=ADC.imag.NCO.real + ADC.real*NCO.imag ADC.imag=0 ==> out.real=ADC.real*NCO.real out.imag=ADC.real*NCO.imag Greetings, Martin
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