Power/Energy Signal Homework: u[n] - u[n-4]

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Discussion Overview

The discussion revolves around determining whether the signal defined by u[n] - u[n-4] is classified as a power signal or an energy signal. Participants explore definitions and calculations related to the signal's energy and power characteristics.

Discussion Character

  • Homework-related

Main Points Raised

  • One participant expresses uncertainty about how to proceed with the problem, seeking assistance.
  • Another participant suggests that the classification can be determined by inspecting the definitions of energy and power signals, hinting at a formula involving the squared magnitude of the signal.
  • A participant calculates that u[n] - u[n-4] equals 1 for n=0,1,2,3 and 0 elsewhere, leading to an energy calculation (Ex) of 4, proposing that this indicates it is an energy signal.
  • A later reply agrees with the previous calculation and classification as an energy signal, prompting a question about the significance of the value "4" in this context and what it would imply if the result were different.

Areas of Agreement / Disagreement

There is a general agreement among participants that u[n] - u[n-4] is an energy signal based on the calculations presented, but there is an ongoing inquiry into the implications of the specific energy value obtained.

Contextual Notes

The discussion does not resolve the implications of different energy values on the classification of the signal, nor does it clarify the definitions of energy and power signals in detail.

smart_worker
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Homework Statement


Determine whether u[n] - u[n-4] is a power or energy signal.

Homework Equations


form.PNG


The Attempt at a Solution


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I am stuck here. I don't know how to simply further. Please help.
 
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You could tell by inspection based on the definitions of "energy signal" and "power signal". If you want to use that formula, what can you say about the equivalence of u[n] - u[n-4] and |u[n] - u[n-4]|2 ?
 
lewando said:
You could tell by inspection based on the definitions of "energy signal" and "power signal". If you want to use that formula, what can you say about the equivalence of u[n] - u[n-4] and |u[n] - u[n-4]|2 ?

I think u[n] - u[n-4] = 1 for n=0,1,2,3 and 0 elsewhere.
So, Ex becomes 4. So, it's an Energy Signal. Am I right?
 
smart_worker said:
I think u[n] - u[n-4] = 1 for n=0,1,2,3 and 0 elsewhere.
So, Ex becomes 4.
That is exactly right.
So, it's an Energy Signal.
You might want to indicate (for others who might want to follow your logic) what is so special about "4" that leads you to classify the signal as you have. What if the result was "5"?
 

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