Quote:
Originally Posted by EricVanWyk
You may see it refered to as "FFT" for "Fast Fourier Transform". For whatever reason, that extra F got into the lexicon.
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The Fast Fourier Transform is a specific implementation, based on powers of two and something called a "butterfly" operation. It's very well optimized for digital computers.
For DTMF decoding, there is an even more specific implementation called the Goertzel algorithm. It simultaneously computes the "DFT" for "
Discrete Fourier Transform" at all seven (or eight) frequencies of interest. It's a lot faster than doing a full FFT over the entire range of frequencies.
A quick Google search shows that there's a
goertzel MathScript function in LabVIEW. The book
Digital signal processing system-level design using LabVIEW appears to have a complete DTMF decoder as one of its lab exercises.