I don't know much about this patent other than what I read in the past few minutes, but: 1. The claims don't cover "use FFT, get key features". It actually cla

I don't know much about this patent other than what I read in the past few minutes, but: 1. The claims don't cover "use FFT, get key features". It actually claims something different but quite broadly. 2. Having some background in signal processing, I can tell you it's never that simple. Many years ago, I once took on a similar project that looked like "oh, a simple frequency-domain cross-correlation should suffice" and it turned into a multi-month exercise that ended without a satisfactory solution. I'm guessing the right solution would have looked a lot like this patent. Taking this use case, for instance: What's a "key feature" that works best for your use case? You do an FFT, fine. What next? What do you hash? How do you hash it in a way to get something useful? You have a ton of information: phase, frequency, amplitude for an N-point FFT, and you have M such chunks of FFTs. How do you use these M x N points to solve your problem? Can you come up with something (without reading the patent, of course) that works reasonably well in a reasonably short time frame?