OK, so over in this other thread they're picking my poor li'l 3-transistor headphone amplifier apart, doing all kinds of FFT stuff with it and all. So I'd like to be able to do the same, just to be able to keep up there.
Now, I know about the FFT viewer, but I really don't know how to use it. And, as usual, the online help is of absolutely no help. What they say is this:
Followed by a screenshot of the FFT dialog. WTF?????
So I know how to select the trace to perform the FFT analysis on. That's easy.
I know I can select the "number of data point samples in time", although I really don't know what this does, but I assume that more is better (but may also take more time to simulate).
"Binomial Smoothing done before FFT and windowing/Number of points"? Right over my head. (Default is 3.)
Now we come to the worst part: the Windowing Function. Not only do I have no frigging idea what this is, but I now have a dizzying array of choices:
Are any of these guys available on-line to ask them how to use their algorithm? (Just kidding.)
So I would very much appreciate it if anyone could point me to a set of choices here that works and will allow me to see the distribution of harmonics in my little amp's output. (Or to a decent explanation of how to use this function.)
I guess LTspice is like a lot of similar software packages: extremely powerful, widely used, and very poorly documented.
Now, I know about the FFT viewer, but I really don't know how to use it. And, as usual, the online help is of absolutely no help. What they say is this:
3. Display the Fourier Transform of a Trace.
You can use the menu command View=>FFT to perform a Fast Fourier transform on various data traces.
Followed by a screenshot of the FFT dialog. WTF?????
So I know how to select the trace to perform the FFT analysis on. That's easy.
I know I can select the "number of data point samples in time", although I really don't know what this does, but I assume that more is better (but may also take more time to simulate).
"Binomial Smoothing done before FFT and windowing/Number of points"? Right over my head. (Default is 3.)
Now we come to the worst part: the Windowing Function. Not only do I have no frigging idea what this is, but I now have a dizzying array of choices:
- Bartlett
- Bartlett-Hann
- Blackman
- Blackmann-Harris
- Blackman-Nuttall
- Bohman
- Cosine
- etc., etc., etc.
Are any of these guys available on-line to ask them how to use their algorithm? (Just kidding.)
So I would very much appreciate it if anyone could point me to a set of choices here that works and will allow me to see the distribution of harmonics in my little amp's output. (Or to a decent explanation of how to use this function.)
I guess LTspice is like a lot of similar software packages: extremely powerful, widely used, and very poorly documented.