Good day,
We wanted to record an AWGN signal between 5 - 65 MHz with the Ettus N320 SDR, save it in an I/Q file and then play it back.
Using GnuRadio, we used a flowgraph for recording and saving to a file and a flowgraph for playing back the file.
You can see the original AWGN signal in the picture (black line).
We have set the SDR to a center frequency = 32 MHz with a sampling rate = 125 MHz. After playback we observed the signal on a spectrum analyzer (blue line).
You can see a spike at 32 MHz and another one at 64 MHz (harmonics). Furthermore, from 5 - 32 MHz the blue signal does not correspond to the original signal.
In order to have the spike at 32 MHz outside of 5 - 65 MHz, we set the center frequency to 67 MHz (green line). Now the spike is outside our original signal but at the lower frequencies down to approx. 35 MHz the signal is
not the original.
My question is, what would be the correct approach for our application? You can see our Gnuradio flowgraphs in the attachment.
Kind regards
