Fourier effect of time shift + convolution

In summary, the Fourier effect of a time shift is a multiplication with an exponential, and when convolving Y(f) with either X(f) or exp(-j2∏f*t0)X(f), the difference is that the former is a normal multiplication of x(t-t0) and y(t) in the time domain, while the latter is a multiplication of their Fourier transforms in the frequency domain. The Fourier transform is a representation of functions in the frequency domain, while convolution is a way of combining frequency contributions.
  • #1
azay
19
0
Ok, I know the Fourier effect of a time shift is a multiplication with an exponential:

x(t-t0) → exp(-j2∏f*t0)X(f)

Now say Y(f) is the Fourier transform of y(t).

What I am wondering what is the difference in the Fourier space when convolving Y(f) with either X(f) or exp(-j2∏f*t0)X(f) respectively? (and why)
 
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  • #2
If you want me to improve your intuition of the Fourier transform and convolution, that would be very hard.

but if you want to know physically what's the difference between convolving with e^(...)X, isn't it just in correspondence with normal multiplication of x(t-t_0) and y? Multiplying two signals should just multiply there amplitude at each moment in time.

The Fourier transform is weird, it's all referring to functions of frequency, not time. Convolution is maybe just a funny way to add up all the frequency contributions.
 

1. What is the Fourier effect of time shift?

The Fourier effect of time shift refers to the change in the frequency spectrum of a signal when it is shifted in time. This effect is caused by the multiplication of the Fourier transform of the original signal with a complex exponential function representing the time shift.

2. How does the Fourier effect of time shift affect the amplitude and phase of a signal?

The Fourier effect of time shift does not change the amplitude of the signal, but it does introduce a phase shift that is dependent on the amount of time shift applied. This means that the shape and magnitude of the frequency spectrum remain the same, but the phase values are shifted.

3. What is the relationship between Fourier effect of time shift and convolution?

The Fourier effect of time shift and convolution are closely related concepts. Convolution can be thought of as a mathematical operation that combines two signals, and the Fourier effect of time shift is one of the ways that the frequency spectrum of the resulting signal can be altered.

4. Can the Fourier effect of time shift be reversed?

Yes, the Fourier effect of time shift can be reversed by applying a time shift in the opposite direction. This can be done by multiplying the frequency spectrum with a complex exponential function representing the negative time shift.

5. How is the Fourier effect of time shift used in signal processing?

The Fourier effect of time shift is a useful tool in signal processing for tasks such as filtering and deconvolution. It allows for the manipulation of a signal's frequency components by applying a time shift, which can help isolate or remove certain frequencies from the signal.

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