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| FFT in LTSPICE XVII - force settings |
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| fcb:
Is there a way to force the setting of the FFT in LTspice (using XVII). I'm already using the .four operative to create THD readouts successfully and also the FFT (View>FFT). Problem is that it (FFT) doesn't seem to remember my 'specify a time range/time range' choices and requires resetting every simulation run (although it does remember my choice of window?). ?Any ideas if their are some operatives/instructions to force the the FFT? |
| SiliconWizard:
IIRC, the View/FFT computes an FFT over the portion of signal in the current window by default. I don't think there is any other way to make it "remember" the time range. So your best bet, if you want to issue an FFT over a specific time range, would be to define this time range in the transient simulation (time to start saving data/stop time). |
| fcb:
Thanks SiliconWizard. That fix does work and is saving my sometime. Still be nice if their were .op options to force the settings of the FFT, perhaps someone from LT/AD will read this. |
| Jay_Diddy_B:
--- Quote from: fcb on May 18, 2020, 09:37:02 am ---Is there a way to force the setting of the FFT in LTspice (using XVII). I'm already using the .four operative to create THD readouts successfully and also the FFT (View>FFT). Problem is that it (FFT) doesn't seem to remember my 'specify a time range/time range' choices and requires resetting every simulation run (although it does remember my choice of window?). ?Any ideas if their are some operatives/instructions to force the the FFT? --- End quote --- Can you share your model? or an example with the same challenges? There may be a solution. Regards, Jay_Diddy_B |
| fcb:
Sorry Jay_Diddy_B. It's under a fairly draconian NDA. For anybody else searching how to do an FFT or THD (.four) using LTspice, this is the main resource I used: |
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