SoliS wrote on Nov 22nd, 2011, 8:20am:...
what about just increasing the length of the time vector and not cutting out the settling time? this would reduce its effects on the DFT.
But slowly. Dropping them is usually much more effective.
NB: 20dB/decade roll-off is caused by a discontinuity in the periodically extended signal.
Quote:though I realize it is more unrealistic to leave it in there, as the DFT will show me what happens when I have a startup settling time every X periods of my waveform. I assumed this part of the waveform would be de-emphasized by the window in the first place. (it's only ~20 points of settling time out of a 100k point vector).
Yes. But if you remove those ~20 points before windowing, there is much less to do for the windowing function. You may not even need any windowing if you use enough points for settling.
Quote:Also, any recommendations for what type of window to use?
Note: A window in the time domain is essentially a "low-pass filter in the frequency domain".
Quote:... I am trying to show the effects of low pass filtering on the image peaks of a sampled-and-held and reconstructed waveform.
- B O E