This is an Excel workbook calculating the Fourier transform of a signal.
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Hello, George. Why do we divide the “cos” and “sin” totals by 20000?
I need to look deeper into this. It might just be some arbitrary scaling.
Hi George, Any thoughts? If considering speed, what would be a realistic data point limit? Thanks.
Yes that’s easy to do, except it’s going to be slow. I chose the limits you see there for speed reasons.
Thanks. What was the largest data points you used besides the demo version?
This is a great tool! Thanks!
If I need to include more data points, how would I do it? Thanks.
How many points you need?
10X of the current limit.
I love this tool. used in work place to demo something.
Thanks for your sharing.
Thanks Harold.
Ishan, what you have here is not a general solution. The way the algorithm was written, it can only extract a FT from a real function. Right now I don’t have the time to add to it. Maybe later.
I used this workbook and seemed pretty handy. Thanks. But I am having trouble doing an inverse FFT in excel using the values from this workbook(excel is returning complex values instead of real numbers). Can you post a solution to this? If it is possible to an inverse FFT compatible to the algorithm used in this workbook
Hi, I am trying to generate fourier transform graph on Unusual excel by using my own data points and time blocks. When I copy and paste my data points under Custom 1, I dont get an appropriate fourier transform. Should I type them in in a form of functional equation? Or can I just plug in numbers ? what do I have to do to generate fourier transform based on my own data points?
How long is the data series? I wrote the whole thing for a certain length. You might have to go in the macro and change the number. Let me know the length.
Hi, George;
It is very good one, I love it. I am learning how to use it properly. I plug in my own data points and time blocks such that I copy and paste my data points under Custom 4, and time blocks at Column 3, changed stop frequency to 10000, then choose Function #4 and run, I do not get an appropriate fourier transform. My data points is 2000 and time increase is 0.005. what should I do in order to make it work with any my own data points?
Thanks,
Looked like a very useful tool, but is almost unusable. Its so slow in Excel 2010 – even for your examples. I think I will have to resort to FFTW or other package
Liberty,
That is unfortunate. Try minimizing the chart or the whole Excel window in 2010 while is calculating. It must be 10x faster this way. After it’s finished you could increase the chart or the window. Good luck!
I have since discovered that having a second spread sheet opened slows the process. Once I close the second spreadsheet performance picks up considerably and it becomes very usable.
Its very nice. Ever considered an “inverse transform” option ?
I want to build an inverse as well as a DFT both direct and inverse. I’ve been too busy lately with insurance claims and a contract I need to finish.