Difference in waterfall display using osmocom_fft

[wpats]

Hi,

I used my bladeRF x40 to observe a signal using osmocom_fft in waterfall displat mode. The signal of interest is spread almost evenly between around 746MHz and 756MHz and turns on and off intermittently. I see a difference in the waterfall display between using 24Ms/sec and 28Ms/sec sample rates. The former shows a nice blocked pattern in time. The latter does not show this clear structure and is diffused. This is the screenshot of the 24Ms/sec display https://www.dropbox.com/s/hqkv0hmmqlfhz ... 1.png?dl=0 and this is the screentshot of the 28Ms/sec displayhttps://www.dropbox.com/s/to6t7wkpiz8xt ... 2.png?dl=0 What is the reason for this difference ? The only parameter different is the sample rate. The time scale is the same. With the sample rate set to 20Ms/sec I see the same diffuse pattern. Only 24Ms/sec shows the accurate display. What is special about this ?

I would appreciate any explanation/help.

Thanks,

--Patrick