I am presently experiencing difficulty in performing FFT for frequency below 1Hz

[olaola2017]

Good day,

I am presently attempting to do an Impedance analysis which involves the division of the frequency response of voltage and current (V/I). However, I am having serious challenges with performing this operation at the low frequencies (1Hz - 10mHz). How I code currently is by using an Index array to specify the frequency bin (for the particular frequency) that I want to divide. However, for the low frequencies the index array doesn't accept figures less than one. Moreover my sampling frequency and number of samples is both set at 100,000Hz and 100,000 samples. 

I will appreciate help with this. Please find attached my code. Thanks 

[GerdW · Accepted solution]

Hi olaola,

sampling frequency and number of samples is both set at 100,000Hz and 100,000 samples. 

That gives you a frequency resolution of 1Hz after the FFT…

When you want a finer resolution you need to increase the sample count!