Average power of a signal in spectral display

Click For Summary
SUMMARY

The discussion centers on calculating the average power of a modulated signal Y(f) with a bandwidth of W=100 kHz. The user initially applied Parseval's theorem, resulting in an energy calculation of 400 KJoules, but expressed confusion regarding the correct interpretation of the signal's units and the integral's application. It is established that the signal is likely a power signal, and the correct units for Y(f) should be V/sqrt(Hz) rather than volts. Additionally, it is clarified that Parseval's theorem provides energy, not power, necessitating a modification of the integral for accurate power calculation.

PREREQUISITES
  • Understanding of Parseval's theorem in signal processing
  • Knowledge of spectral analysis and signal modulation techniques
  • Familiarity with units of measurement in signal processing, specifically V/sqrt(Hz)
  • Basic calculus for performing integrals
NEXT STEPS
  • Study the application of Parseval's theorem for power signals
  • Learn about the differences between energy and power in signal processing
  • Explore spectral analysis techniques for modulated signals
  • Investigate the implications of unit conversions in signal representation
USEFUL FOR

Electrical engineers, signal processing specialists, and students studying modulation techniques and spectral analysis will benefit from this discussion.

axcelenator
Messages
33
Reaction score
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!
 

Attachments

  • fourier.jpg
    fourier.jpg
    14 KB · Views: 509
Physics news on Phys.org
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.
 
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.
 

Similar threads

  • · Replies 1 ·
Replies
1
Views
2K
Replies
5
Views
4K
  • · Replies 4 ·
Replies
4
Views
6K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 26 ·
Replies
26
Views
6K
  • · Replies 3 ·
Replies
3
Views
26K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 7 ·
Replies
7
Views
3K
  • · Replies 12 ·
Replies
12
Views
3K