Average power of a signal in spectral display

In summary, the conversation discusses a modulated signal with a spectral modulated signal and a carrier of several COS. The question asks for the average energy or power of the signal at a given frequency. The speaker believes it is a power signal and has attempted to calculate it using Parseval's theorem but is unsure if it is correct due to the signal not being periodic. They also mention being confused about the units of the signal and suggest considering the y-axis as V/root Hz. They also point out that the integral must be modified for accuracy.
  • #1
axcelenator
33
0
Hello, I've got a modulated signal - Y(f) (the question doesn't say if AM or DSB or whatever) which it's spectral modulted signal is shown(in the file I've uploaded).its is modulated by a carrier of sum of several COS.

It asks what is the average energy or power( I should decide) of the modulated signal y(t)^2 - if W=100kHZ.


I think that it is power signal.
I've tried to do that with parseval:∫|Y(f)|df from and got 400KJoule. but I don't know wheter it right or wrong and I don't know how to do the Integral because it is not periodic.
Thanks!
 

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  • #2
I am a bit confused that Y is expressed in volts. I think it should be V/root Hz or V^2/Hz since there is clearly a continuum of frequencies in a bandwidth of W. If it were V then there would be an infinity of spot frequencies in a bandwidth W with attendand infinite power.

So unless you get better info I would consider the y-axis as V/root Hz, then you can easily determine the total power by looking at the +x axis spectral distributions.
 
  • #3
In addition to the erroneous units that rude man pointed out, please note that 1) Parseval's theorem gives you energy, not power, and 2) your integral must be modified to be correct.
 

What is the average power of a signal in spectral display?

The average power of a signal in spectral display is a measure of the signal's strength over a period of time. It is calculated by taking the average of the squared values of the signal amplitude over the entire period.

Why is the average power of a signal important?

The average power of a signal is important because it gives an indication of the signal's energy and can be used to compare different signals. It is also used in various engineering and scientific applications, such as in the design and analysis of communication systems.

How is the average power of a signal calculated in spectral display?

The average power of a signal in spectral display is calculated by first obtaining the power spectral density (PSD) of the signal, which is a measure of the signal's power at different frequencies. The average power is then calculated by integrating the PSD over all frequencies.

What is the difference between average power and peak power of a signal?

The average power of a signal is the average strength of the signal over a period of time, while the peak power is the maximum strength of the signal at any given moment. The average power takes into account the signal's strength over time, while the peak power only considers the maximum value.

How does the average power of a signal affect its spectral display?

The average power of a signal affects its spectral display by influencing the height of the signal's spectrum. A higher average power will result in a taller spectrum, while a lower average power will result in a shorter spectrum. This is because the average power is directly related to the amplitude of the signal in the frequency domain.

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