special functions – Microfluctuations analysis and Power spectrum

I measured a parameter over time and obtained the values below:

0,627896 0,205004 0,259237 1,059125 0,832184 0,587992 0,565537 0,527323 0,460228 0,471958 0,26696 0,75367 0,892273 0,789401 1,089945 0,579791 0,421917 0,677286 -0,34936 -0,16841 -0,24775 0,813205 0,421242 -0,15486 0,612315 0,953073 0,561099

The values were obtained every 0.5 seconds.

How can I get the power spectrum in mathematica? And how can I calculate the amplitude of microfluctuations?

Thanks
I have no ideia how to start.