Computing the Hilbert transform via Fourier transform

In summary, the conversation discusses using the fft and ifft commands in MATLAB to compute the Hilbert transform, and the use of the sign function for this purpose. The sign function is described as returning an array where each element is 1, 0, or -1 depending on the value of the corresponding element in the input array. It is confirmed that the sign function can be used for computing the Hilbert transform.
  • #1
hunt_mat
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I know the result: [tex]\widehat{H(f)}=i\textrm{sgn}\hspace{1mm}(k)\hat{f}[/tex]

I thought I could use fft, and ifft to compute the transform easily, is there a MATLAB command for sgn?

Mat
 
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  • #2
Yes, sign!

sign
Signum function

Syntax
Y = sign(X)

Description
Y = sign(X) returns an array Y the same size as X, where each element of Y is:

1 if the corresponding element of X is greater than zero

0 if the corresponding element of X equals zero

-1 if the corresponding element of X is less than zero

For nonzero complex X, sign(X) = X./abs(X).
 
  • #3
Is it okay for computing the Hilbert transform?
 

1. What is the Hilbert transform?

The Hilbert transform is a mathematical operation that is used to obtain the analytic representation of a signal. It is commonly used in signal processing and mathematics to find the instantaneous amplitude and phase of a signal at any given point in time.

2. How is the Hilbert transform computed?

The Hilbert transform can be computed using the Fourier transform. The Fourier transform of a signal is multiplied by the sign function, which is a mathematical function that changes the sign of a signal at every point. The inverse Fourier transform of this product results in the Hilbert transform of the original signal.

3. What is the significance of computing the Hilbert transform via Fourier transform?

Computing the Hilbert transform via Fourier transform is significant because it provides a fast and efficient method for obtaining the analytic representation of a signal. This allows for easier analysis and processing of signals in various fields, such as telecommunications, image processing, and biomedical engineering.

4. Is the Hilbert transform via Fourier transform always accurate?

Yes, the Hilbert transform via Fourier transform is always accurate. This is because the Fourier transform is a well-defined mathematical operation and the sign function is a deterministic function, meaning it always produces the same output for a given input. Therefore, the result of the Hilbert transform via Fourier transform will always be accurate.

5. Are there any limitations to computing the Hilbert transform via Fourier transform?

One limitation of computing the Hilbert transform via Fourier transform is that it assumes the signal is stationary, meaning it does not change over time. This may not be the case for all signals, and can result in inaccuracies in the computed Hilbert transform. Additionally, the Fourier transform requires that the signal is bandlimited, meaning it contains only a finite range of frequencies. If the signal is not bandlimited, the computed Hilbert transform may be incorrect.

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