[Discuss-gnuradio] Multiplying 2 signals from the grc

[guelord ingala]

Hi all,
I need to multiply 2 signals (800 MHz and 820 MHz) from external signal generators. I used the usrp-1 and DBSRX daughter-boards to detect the 2 signals. I attached the grc file that I created for this application. I can detect signal from the output  of the usrp source.

When I multiply, I expect to have 2 components (sum and difference) at 20 MHz and 1.620 GHz. To visualize these 2 components, I need to set the FFT-sink to display a wide range. This means the FFT sink sample rate must be high i.e 3.4 G. With this value, the FFT doesn't display the plot. I used a Rational Resampler to match the usrp source sample rate with the FFT sample rate. But it's still not working.

Can anyone tell me how to fix this. Your help will be appreciated.
Dominique
Regards.

Screenshot at 2012-04-06 10:30:15.png
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