LabVIEW
signal compression whit FFT
Hopefully, this thread will be moved, so I can start replying here:
Your code makes absolutely no sense. What kind of compression do you have in mind? Can you point to a web site that describes the algorithm?
It almost looks like you want to keep only the major frequencies, but whatever you are doing seems silly and your order of operations does not seem correct. You are doing an FFT, throw away the phase information, and transform right back, again throwing away phase information then thresholding the backtransform. Makes no sense.
You could do an FFT, retain the complex components that have a magnitude above a threshold, then do a inverse real FFT to reconstruct the signal.
Also, you use charts instead of graphs.
altenbach wrote:You could do an FFT, retain the complex components that have a magnitude above a threshold, then do a inverse real FFT to reconstruct the signal.
Here's a quick draft (LabVIEW 8.0). Most likely it needs some tweaks. 😉
You also have significant spectral leakage, because (using your default values) the sample interval is not an integer multiple of your fundamental frequencies. If you would set fe=512, things look significantly better.
