Re: [Discuss-gnuradio] Basic RX/TX

[Angilberto Muniz Sb]

Sorry if it sounds silly, but why one is supposed to
get DC out of the DAC if Carrier Freq is set to zero?

What if one generates a 1Mhz QPSK in GNURadio ? Its
not zero hertz, its baseband...
Im puzzled...

Angilberto.

--- Matt Ettus <address@hidden> wrote:

> On Sat, 2006-05-27 at 12:16 -0700, Thomas Schmid
> wrote:
> > Hi,
> > 
> > I have a question about the basic RX/TX boards.
> What should I see if I
> > hook the basic TX board to an oscilloscope if I
> send out a QPSK
> > signal? Here is what I do:
> > - I generate a QPSK signal in GnuRadio
> > - I send the signal to a complex file source and
> the signal looks right
> > - I send the signal to the complex USRP source and
> have a BasicTX on
> > it. The outputs TXA and TXB are hooked up to a
> oscilloscope on channel
> > 1 and 2 respectively.
> > 
> > Now, what should I see on the oscilloscope? Is it
> the baseband signal?
> > How does the I and Q phases get mixed together?
> Does that depend on
> > the mux values? Unfortunately I couldn't find a
> good block diagram of
> > the TX path on the wiki, i.e., the link to [A
> system block diagram of
> > the USRP receiver and transmitter path] on the
> wiki page
> >
>
"http://www.comsec.com/wiki?UniversalSoftwareRadioPeripheral";
> is dead.
> 
> If you set the carrier frequency to 0 you will see
> the I signal on the I
> channel out and the Q signal on the Q channel out. 
> This will only be
> useful with the LFTX board since the BasicTX will
> block DC.
> 
> If you set the carrier frequency to something other
> than 0, then the I
> and Q signals will be upconverted and sent to the
> outputs.  As long as
> the carrier frequency is greater than your signal
> bandwidth, then you
> only need either the I output or the Q output since
> they are now
> double-sided real signals.  You can still use the I
> and Q connectors
> with an image-reject mixer if you need.
> 
> Matt
> 
> 
> 
> _______________________________________________
> Discuss-gnuradio mailing list
> address@hidden
>
http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
> 


__________________________________________________
Do You Yahoo!?
Tired of spam?  Yahoo! Mail has the best spam protection around 
http://mail.yahoo.com