# FFT giving a huge magnitude of first frequency and pretty much zero after that

So I have a (visually) very noisy time series signal and I have applied the fast Fourier transform using numpy's fft function. I am wondering why I am seeing the magnitude of the coefficient for the first frequency very large, actually equal to the number of samples ( 256 samples ) in the data, and the rest of the coefficients very low.

I am assuming this means there there is no periodic signal being extracted from the data, but I wanted to get a second opinion about it. How do I interpret this result? Maybe I am doing something wrong.

Input Signal:

Frequency Coefficients:

Zoomed Picture:

• That's not particularly noisy. You have just zoomed in a lot. – mathreadler Nov 30 '19 at 15:31