4 ms·
Why use an FFT at all? Yes it's easy but you'll almost always get a better result with a lot less computation by building an actual digital filter.
by dreamcompiler 6y ago
Why use an FFT at all? Yes it's easy but you'll almost always get a better result with a lot less computation by building an actual digital filter.
- midjji 6y agoApplying a FIR in frequency domain faster for 1D filters longer than some very small number, usually 7-16. The old school graphics and audio filters are shorter sure, but they are also horribly bad compared to what you can do with a designed filter in the 20-40 range.
- CamperBob2 6y agoAn IIR filter will always beat an FFT, but the most efficient way to implement longer FIR kernels is often with a WOLA or similar "streaming" FFT filter implementation. At some point, it takes fewer cycles to do N*log(N) multiplication in the frequency domain than to do N^2 multiplications to convolve in the time domain. The crossover point will be system-dependent and heavily influenced by overhead, but a crude WAG might be in the vicinity of 64- to 128-wide kernels. There is no question of one implementation being "better" than the other, they are capable of identical results if implemented accordingly.
- rightbyte 6y agoWhen you want to do signal analysis in the frequency domain?
- kroeckx 6y agoSome standards define a frequency response of the whole measurement chain, including things like the frequency response of your sensor and anti aliasing filter. An FFT is the easiest way to deal with that.