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Re: [Discuss-gnuradio] USRP DDC usage

From: Eric Blossom
Subject: Re: [Discuss-gnuradio] USRP DDC usage
Date: Thu, 26 May 2005 19:34:53 -0700
User-agent: Mutt/1.5.6i

On Thu, May 26, 2005 at 01:36:28PM -0400, Krzysztof Kamieniecki wrote:
> Quoting Achilleas Anastasopoulos <address@hidden>:
> > 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)?

That's what I would expect.

> > 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)

I think I'm missing the question.   Set nchannels to 2 and the output
of the two DDCs will be interleaved.  You deinterleave to separate

See gnuradio-examples/python/usrp/wfm_rcv_many.py for an example that
separates the output from more than one DDC.


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