tinySA | Main / Resolution Filters

The first filter in the tinySA is the band pass filter of the 1st IF.
It has a bit of an odd shape but it does a good job in removing the image that would otherwise reduce the sensitivity.

(ifend:)

The tinySA resolution filters are implemented in DSP code. Here is the shape of each of the selectable resolution filters. The the displayed span is always 10 times the selected RBW. The side lobes are caused by spectral leakage in the DSP filter. The noise floor moves up with decreasing bandwidth due to the phase noise.

600kHz

The side lobes are mostly removed by the 1st IF filter

300kHz

Also here the side lobes are mostly removed by the 1st IF filter.

100kHz

As the side lobes now fit within the passband of the 1st IF filter they become visible

30kHz

10kHz

The impact of the phase noise is visible with the noise floor moving up

3kHz