Quoting Martin Dvh <[EMAIL PROTECTED]>: > 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 >
And NCO.imag is only zero if the NCO frequency has not been changed from zero since USRP powerup. _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
