How to recover the phase of the sine signal?

How to recover the phase of the sine signal?

First fftshift (rotate by N/2) the data to move the zero phase reference point to the center of the window before doing the FFT. (This is needed to keep the phase from flipping/alternating between adjacent FFT result bins. * ) Then do the FFT and estimate the frequency of the sinusoid by parabolic or, better yet, Sinc interpolation.

When to use non-interpolated FFT result phase?

Using an non-interpolated FFT result phase only works if the period of sinusoid is exactly an integer submultiple of the FFT length. In your example, the sine wave isn’t integer periodic in aperture. If not, you will need to interpolate the phase to get a better estimate.

What should the length of the FFT function be?

The FFT function computes -point complex DFT. The length of the transformation should cover the signal of interest otherwise we will some loose valuable information in the conversion process to frequency domain. However, we can choose a reasonable length if we know about the nature of the signal.

How to obtain a double-sided plot using FFT?

For obtaining a double-sided plot, the ordered frequency axis (result of fftshift) is computed based on the sampling frequency and the amplitude spectrum is plotted. 3b. Extract phase of frequency components (phase spectrum) Extracting the correct phase spectrum is a tricky business. I will show you why it is so.

How is the FFT used in signal analysis?

Computations Using the FFT The power spectrum shows power as the mean squared amplitude at each frequency line but includes no phase information. Because the power spectrum loses phase information, you may want to use the FFT to view both the frequency and the phase information of a signal.

How is the amplitude spectrum obtained from fftshift?

The amplitude spectrum is obtained For obtaining a double-sided plot, the ordered frequency axis (result of fftshift) is computed based on the sampling frequency and the amplitude spectrum is plotted. 3b. Extract phase of frequency components (phase spectrum) Extracting the correct phase spectrum is a tricky business.

How to interpolate the phase of a sine wave?

In your example, the sine wave isn’t integer periodic in aperture. If not, you will need to interpolate the phase to get a better estimate. Here’s one method to get an better interpolated phase: First fftshift (rotate by N/2) the data to move the zero phase reference point to the center of the window before doing the FFT.