Continuous Time Fourier in LTI system

In summary, for the given homework statement, the student is unsure of how to approach the problem and asks for guidance. The conversation then suggests using the definition of power and the Fourier transform to solve Part A, and using the transfer function and |H| to solve Part B. The student expresses confidence in being able to figure it out with the suggested methods.
  • #1
beanus
17
0

Homework Statement


Capture.jpg



Homework Equations


Not sure


The Attempt at a Solution


No idea how to even begin.

I don't even know how to start this equation. My textbook has no examples of this type. Do I need to transform x(t)? If someone could simply steer me in the right direction I'm confident I can figure it out.
 
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  • #2
beanus said:
I don't even know how to start this equation. My textbook has no examples of this type. Do I need to transform x(t)? If someone could simply steer me in the right direction I'm confident I can figure it out.
For Part A. You can solve this several different ways. If you don't know what to do, you should always resort to the definition of power. But in this case you should know that you can also find the power of a signal from its Fourier transform and this particular signal has a really simple Fourier transform. Normally I would just compute the power of the sinusoids from rms values but part A is leading into part B.

For Part B, the transfer function shows how sinusoids are transformed by the system. Your input is the sum of two sinusoids. Again, there is more than one way to do this one but the question is practically begging you to use |H| somehow. From part A you should have the spectrum of X and therefore its magnitude too.
 
Last edited:

1. What is the Continuous Time Fourier Transform (CTFT)?

The Continuous Time Fourier Transform (CTFT) is a mathematical tool used to analyze signals in the time domain and represent them in the frequency domain. It is particularly useful in studying Linear Time-Invariant (LTI) systems, which are systems that do not change over time. The CTFT converts a continuous time signal into a continuous frequency spectrum, providing valuable information about the frequency content of the signal.

2. How is the CTFT different from the Discrete Time Fourier Transform (DTFT)?

The main difference between the CTFT and the DTFT is that the CTFT deals with continuous time signals, while the DTFT deals with discrete time signals. This means that the CTFT is used for signals that are continuous in both time and frequency domains, while the DTFT is used for signals that are discrete in both domains.

3. What is the relationship between the CTFT and the Fourier Series?

The Fourier Series is a special case of the CTFT, where the input signal is periodic. It is used to decompose a periodic signal into a series of sinusoidal components. The CTFT, on the other hand, is used for non-periodic signals and provides a continuous frequency spectrum.

4. How can the CTFT be used to analyze LTI systems?

The CTFT can be used to analyze LTI systems by converting the input signal into the frequency domain and then applying the system's frequency response to obtain the output signal in the frequency domain. The output signal can then be transformed back into the time domain using the inverse CTFT. This allows for a better understanding of how the system affects different frequencies in the input signal.

5. What are the limitations of using the CTFT in analyzing LTI systems?

One of the main limitations of using the CTFT to analyze LTI systems is that it assumes the system is time-invariant, meaning that its behavior does not change over time. In real-world situations, many systems are not completely time-invariant, which can lead to errors in the analysis. Additionally, the CTFT is only applicable to signals that are absolutely integrable, which means that the signal's energy is finite over all time.

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