Re: [Discuss-gnuradio] questions about USRP2 sink block and upconversion

[Markus Heller M.A. (relix GmbH)]

Hi Marcus,

thanks a lot for sending the flowgraph. I completely understand it and I
am very confident that I can get this going. Only thing, I currently
don't have an external 3,5mm plugged microphone :-)

BR
Markus
DL8RDS

Am Mittwoch, den 03.11.2010, 23:54 -0400 schrieb Marcus D. Leech:
> On 11/03/2010 11:11 PM, Markus Heller M.A. (relix GmbH) wrote:
> > Hi Marcus,
> >
> > great, now I know what was wrong. I didn't expect my dummy load to be so
> > safe. It was a real signal lock :-)
> >
> > For all the others, here's a short experiment report:
> >
> > Here are the parameters:
> >
> >       * Sample rate 200k
> >       * Signal source at 1 KHz, amplitude at a minimum of 0.001 - to
> >         make sure that a bad SWR does no harm. BTW, this is a good
> >         counter check that you can really influence the output power!
> >       * USRP2 sink: interpolation 500, frequency 14 MHz
> >
> > Result: I hear a clear signal at 14.000 MHz, +/- 1 kHz
> >
> > Thanks very much!
> >
> >   
> In the spirit of a "conspiracy of Mar[ck]uses":
> 
> http://www.sbrac.org/files/ssb_xmitter.grc
> 
> It's not actually connected to USRP2, but to an FFT sink, but it samples
> at 200KHz, so one
>   could easily replace that FFT block with an USRP2 block.
> 
> It uses an audio source sampled at 20KHz, and then uses a bandpass
> filter after interpolating
>   up to 200KHz to pick off either the upper or lower side-bands, which
> are limited to a roughly
>   2.7KHz bandwidth:  LSB: -3KHz to -300Hz and USB: 300Hz to 3KHz.
> 
> Audio and baseband signal levels will need to be adjusted, etc, but it's
> a good starting point.
> 
> It uses a "0Hz carrier", which happens to work perfectly when you're
> dealing with a
>  complex baseband signal.
>