My coworker ran a DFT query using a software in C downloaded to his PC. His results was the following chart: enter image description here

I am using a JS tool from corbanbrook/dsp.js

My results were very different. enter image description here

any ideas why, or where to look?

  • $\begingroup$ You could start by not running random software from the internet and go with a known-good library such as FFTW. $\endgroup$ – MBaz Nov 1 '19 at 14:27
  • $\begingroup$ I appreciate that, I did a lot of searching and found most people commenting positively on dsp.js so thats why I selected that for my software. $\endgroup$ – TDawg Nov 1 '19 at 20:14
  1. Make sure you use the same scaling and X and Y axis so you compare apples to apples. The upper graph is in power the lower seems to be amplitude
  2. Start with a known signal with a known answer. A sine wave or square wave for example and compare the outcome with the expected result.
  • $\begingroup$ Good point. Yes, we are both testing with same hz, same data. Point #2 I'll talk to him about so we can compare some results. $\endgroup$ – TDawg Nov 1 '19 at 20:15

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