How do you find the period of a sinusoidal graph in Excel?

Question

I have a great deal of experimental data; it all roughly fits a sine wave. I have been working out the period manually by identifying the peaks and troughs, on an Excel graph; it takes ages... Is there a function, or Data Analysis tool which is able to calculate the period? (The amplitude get small exponentially as well). If not could I make a macro that does the same thing?

Help! Thank you!

Is FFT Fourier analysis? I don't understand!

Answer 1

You need to perform an FFT of your data (which is available in the analysis pak). The FFT will compute the amplitudes of the complex exponential functions (essentially, the sinusoids) that make up your input data. As with any FFT, you need to provide a data set whose size (K) is an even power of 2 (2^10 (1024) or 2^12 (4096) samples works well). The output will then be the coefficients x_n in the equation

The series will be the amplitudes of the sinusoidal components at frequencies defined by

f_n = 2*pi*k*n/N

where k is the discrete time interval represented by your original data.

If you plot the FFT coefficients, you should be able to easily determine the fundamental frequency of your input data.

Answer 2

it is obtainable, whether it is not an extremely sturdy graph. right here is what I did: in the 1st block/cellular (A1) I entered on your equation (y=26+4sin((pi/6)x-one million) ). After that, I chosen the cellular and clicked on the graph icon on the gadget bar. next, I chosen "line" and clicked the "next" button. Then "next" returned, considering the fact that there is no documents, and "next" returned. Then, I clicked "end". i don't think of the graph is an extremely sturdy one, and optimistically I helped. you ought to purpose exploring slightly with some values and consistent with probability the technique. sturdy success.

Answer 3

Can't you just graph it and get an approximation? How precise do you need?