Quoting Achilleas Anastasopoulos <[EMAIL PROTECTED]>: > I have a question/observation on this issue: > > Since the DDC multiplication is complex and since the internal DDC > oscilator is noncoherent, I do not see a difference between the MUX > settings: 0x33221100 and 0xf3f2f1f0. > Is the difference between them a phase shift of 45 degrees and a gain ratio of sqrt(2)?
> Similarly, with the setting 0x00003210 you will never be able to > separate the two channels coming from ADC0/ADC1 and ADC2/ADC3. > You can seperate ADC0/ADC1 and ADC2/ADC3 if you set the DDC frequency to zero (I think you also have to never have set it to a non-zero value after powerup, since you can't reset the DDC phase) > Is this right? > > Thanks > Achilleas > > > > > > On Wed, May 25, 2005 at 02:54:05PM -0400, Philip Balister wrote: > > >> I'm working on making a SCA component for the usrp based on the usrp > >> standard interface. I've got a few questions on how to use the DDC's and > >> the input mux. > >> > >> If I set the mux word to 0x33221100 (and the number of channels to four) > >> I believe I will have 4 channels of complex data from each A2D. > > > FYI, the current fpga image only support two DDCs. > > You always get complex data out of the DDCs. The question is what are > you putting in? > > If you want two DDCs with a different pair of A/Ds to each one > the mux should == 0x00003210 > > > >> If I set the mux word to 0xf3f2f1f0 I will have four channels of real > >> data, interleaved with the zeros from the Q channel. > > > Yes. This will feed a zero to the Q input of each DDC and will feed > ADC's 3, 2, 1, 0 to the I inputs. Note that there are only two > channels available in the current FPGA build. > > Eric > > > _______________________________________________ > Discuss-gnuradio mailing list > [email protected] > http://lists.gnu.org/mailman/listinfo/discuss-gnuradio > _______________________________________________ Discuss-gnuradio mailing list [email protected] http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
