Sample rate / filtering interaction on the xA4
Posted: Wed Sep 20, 2023 4:37 pm
Is there any documentation on how filtering configuration is handled on the xA4? I am using SDRangel as a test bed and am seeing behavior I do not understand. The receiver configuration is shown in the linked images. The input signal is at -60 dBm in all cases.
Sample rate 2083335 Hz and above:
Sample rate 2083335 Hz and above:
- The spectrum for a 1000.2 MHz signal looks like this. The signal strength is about right, but the noise floor looks strange.
- At 1001.1 GHz we get this. The signal is aliased to ~999.02 MHz and is down by only ~15 dB.
- The spectrum looks like this. The noise floor shape is textbook and there is no aliasing of out-of-band signals, but the amplitude is about 11 dB too high.