It seems wrong because there are many android apps for instrumental tuning. And they doesn't take any longer than 1sec for deciding which frequency is playing
Is there anything I can't catch?? I hope any opinions of yoursThanks
With careful interpolation from an appropriately windowed FFT you can measure peak frequency to a lot better resolution than the bin width,
And I can't understand your intend for second question...sorry. Is that important?
at that moment it seems time domain is windowed by rectangular window, other bins are zeros(301~30,000)
Well, the app that I use displays second decimal place.(I'm not sure it really measures or just computes, but can display anyway)
So sampling rate will be 3000hz following Nyquist sampling theory.
If the sample depth is 12 bits, you might be able to linearly interpolate a zero crossing to about 1/200th of a sample period, ie 100ns.
But why 1/200? Isn't it 1/4096(=2^12)?