I was looking in the Android app store for a guitar tuner. I found a tuner app that claimed it was faster than other apps. It claimed it could find the frequency without using the DFT (I wish I still had the URL to this specification).
I have never heard of this. Can you acquire an audio signal and compute the frequency without using the DFT or FFT algorithm?
Answer
FFT is actually not a great way of making a tuner. FFT has inherently a finite frequency resolution and it's not easy to detect very small frequency changes without making the time window extremely long which makes it unwieldy and sluggish.
Better solutions can be based on phase-locked loops, delay-locked loops, auto correlation, zero crossing detection and tracking, max or min detection and tracking and certainly intelligent combination of these methods.
Pre-processing always helps.
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