Re: [Discuss-gnuradio] Signal coming from the USRP to the computer

[Marcus D. Leech]

On 05/29/2011 05:17 PM, John Andrews wrote:
> Of course that is true. I just wanted to make sure my understanding of 
> the whole signal flow in GNU Radio/USRP system was right. The IF, down 
> coversion etc stages confused me a bit. I was only interested in what 
> I am getting on the USB bus to work with so, I wanted to make sure my 
> understanding of this system was right.
>
> Thanks for the reply.
You should perhaps do a literature search on "complex downconverter" or 
"quadrature downconverter" and "direct-conversion receiver" to
  get more understanding.

With one exception, all of the daughtercards use a direct-conversion 
scheme to directly convert from RF to a complex baseband, which
  is described mathematically as you've shown.

I'm always nervous when I see a purely-mathematical description, because 
if you think in terms purely mathematical, without also
  considering the very-real, very-practical, you can be in for some 
surprises.

--
Marcus Leech
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org