Re: [Discuss-gnuradio] USRP and RFX2400 block diagrams

[Eric Blossom]

On Wed, Aug 30, 2006 at 01:28:33PM -0400, Lee Patton wrote:
> On Wed, 2006-08-30 at 06:56 +0000, Eric Blossom wrote:
> > On Tue, Aug 29, 2006 at 10:08:47PM -0400, Lee Patton wrote:
> > > I've taken a shot at coming up with block diagrams for the USRP and
> > > RFX2400.  The diagram for the USRP is the result of information I've
> > > gleaned from different messages in the list, data sheets, and block
> > > diagrams created by other GNU Radio users (specifically, Achilleas
> > > Anastasopoulos).  The RFX2400 diagram was created from Matt's drawings
> > > and associated data sheets. 
> > > 
> > > The diagrams can be found here:
> > > http://www.pattoncentral.org/gnuradio/diagram/
> > 
> > Nice diagrams! Thanks!
> 
> Glad to.
> 
> > Here are a couple of tweaks:
> > 
> > The digital down-conversion should show a single complex multiplier
> > instead of two real multipliers.
> 
> Thanks. I'll make the change.  A complex multiplier is just a more
> efficient digital version of what I've drawn, right?

No.  They're not equivalent.  The naive complex multiplier has 4 real
mulitipliers and two adders:

  (a + bj) * (c + dj) = (ac - bd) + (ad + bc)j 

> > Same comment on the digital up-conversion.  We've got "Block D"
> > enabled in the AD9862, thus it's functioning as a complex multiplier.
> 
> Okay. Out of curiosity, is "Block B" enabled too?

Yes, if it needs to be.

Eric