[bojan]

Yes you are right, waterfall is actually spectrum vs time, and it's very easy to spot features, especially transients.
However, I am not sure this can be recorded with current version of SDR#.. and the data record is essential.
Another problem with recording raw data is the file size..
Since the SDR sample rate is huge, so would be the data file as well..
Maybe SDR# is not the ideal solution after all.. for spectrum analysis that is.
I tried to use my HP 8569B Spectrum analyser for this purpose, but it has limitations as well.. one of them is relatively high internal noise floor, so I need more (variable) gain in front of it (40dB or so).
So for this to do I will have to go for suitable down converter.
Tere are some mixers and VCO's stored in my boxes somewhere..

I am now considering building the AM detector for RF signal, and my own ADC, which can be controlled by SkyPipe.