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

[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.

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