Using FFT

[vsoft]

I consider buying an oscilloscope. Spectral analysis is important to me. That is why I have been using software oscilloscopes until now.
Your manual tells very little about using FFT. Thus I have many questions:

1. What is shown on the screen? I guess it's power spectral density?
2. Is it averaged or instant?
3. Is it possible to have the Y axis in dB?
4. Is screen resolution sufficient to show 512 points?

[jye1]

Display is the FFT of signal voltage. It can be considered as instant. FFT is performed once capture is filled. After FFT another capture starts right away. This FFT only serves as a rough indicator of frequency components since it is not calibrated and the vertical screen resolution is too low for meaningful value display.