# even and odd signals

Discussion in 'Homework Help' started by bhuvanesh, Feb 17, 2015.

1. ### bhuvanesh Thread Starter Member

Aug 10, 2013
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2
Signals can be in nature or we artificially produce it. In nature no signals are going to be in even or odd. so other option we have is to produce.So my next question is why we want to produce such signal(even and odd signal) ?

content form my signal book by oppenheim
why we need to do even-odd decomposition for the signal.what is the use in that ?

2. ### WBahn Moderator

Mar 31, 2012
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Since this is Homework Help, why don't YOU start by giving us YOUR best thoughts as to an answer?

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3. ### bhuvanesh Thread Starter Member

Aug 10, 2013
268
2
i dont get any idea.we can use it to separate sin(odd) and cosine(even) signal .May be in later studies(dft,fourier)i may come to the use of even and odd signal.but so far as now i want to knkow why we decompose odd and even component of signal what is the use of that?

4. ### WBahn Moderator

Mar 31, 2012
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If I tell you that a signal is odd, what does knowing that, all by itself, tell you?

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5. ### bhuvanesh Thread Starter Member

Aug 10, 2013
268
2
nothing its just odd signal,what do you want me to know from that?

6. ### WBahn Moderator

Mar 31, 2012
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What is the average value of an odd signal?

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7. ### bhuvanesh Thread Starter Member

Aug 10, 2013
268
2
Xe(t)=(X(t)+X(-t)/2

8. ### WBahn Moderator

Mar 31, 2012
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Don't know what you are trying to express with this. But if you apply the definition of an odd signal, you might still get at what the average has to be.

9. ### bhuvanesh Thread Starter Member

Aug 10, 2013
268
2
i dont know what is mean average value of an odd signal?

10. ### WBahn Moderator

Mar 31, 2012
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Do you know what is meant if someone were to ask about the average value of a just any old signal?

What does "average" mean to you?

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11. ### bhuvanesh Thread Starter Member

Aug 10, 2013
268
2
Average mean list of numbers divided by number of numbers

Average value of odd signal mean taking integration of odd signal over duration and dividing it by that duration. Am i making any sense

12. ### WBahn Moderator

Mar 31, 2012
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Some, but I'm not convinced that you understand the concept of an "average".

In the first case, if I have the following list of numbers: {10, 20, 30, 40}, your description would mean that the average is {2.5, 5, 7.5, 10}.

I don't think that is what you meant to say, but it is what you actually said.

If I have 20 gallon milk containers and each has a different amount of milk in them and I tell you that the average amount of milk in each container is 0.25 gal, how did I arrive at that and what does knowing that average tell you?

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13. ### bhuvanesh Thread Starter Member

Aug 10, 2013
268
2
i mean summation of list of numbers divided by number of numbers like((10+20+30+40)/4)
it mean you are saying that averagely 2.5 litres in each milk container (some can have little high and low).it is also used to share the equally 2.5 gallons among them. Am i making any sense

14. ### WBahn Moderator

Mar 31, 2012
20,064
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Just knowing that I have 20 containers that have, on average, 0.25 gallons each lets you determine several things. First and foremost you know that I have a total of 5 gallons milk. You don't need to know the details of how much milk is in each container (i.e., a list of 20 different numbers) in order to determine that. So knowing the average tells you something about the collection as a whole. It does NOT tell you everything, nor does it tell you anything about any one of the containers in particular. Sure, you can say that at least five of the containers have at least some milk in them and, similarly, that at most five containers are completely full. You can also assert that there is at least one container that has at least 0.25 gallon in it and, similarly, that there is at least one container that has no more than 0.25 gallons in it. Sometimes being able to assert things like this is all that is needed to solve a problem and sometimes it's not. It's entirely possible that ten of the containers have never had a drop of milk in them ever or that no container has less than a pint of milk or more than three pints -- the knowledge about the average is insufficient to answer these questions.

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15. ### bhuvanesh Thread Starter Member

Aug 10, 2013
268
2
okay,but how would you relate it to my question tachnically. Non technically i am okay with what you saying let get back here
let consider voltage wave here i can say average voltage by rms and current in same analogy ,is what your expecting

16. ### WBahn Moderator

Mar 31, 2012
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I'm expecting a very specific number.

What, by definition, is an odd signal?

What is the average value, over all time (or even over any pair of symmetric limits) of such a signal?

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17. ### bhuvanesh Thread Starter Member

Aug 10, 2013
268
2
okay lets turn the plate i am asking you What is the average value, over all time (or even over any pair of symmetric limits) of such a signal?

18. ### WBahn Moderator

Mar 31, 2012
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This Homework Help, not Homework Done For You. You need to show an effort to work it out. That way I can see where you are going right and where you are going wrong.

Start with the first part. What is the mathematical definition of an odd signal?

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19. ### bhuvanesh Thread Starter Member

Aug 10, 2013
268
2
Thank you sire

mathematical definition is x(t)=-x(-t)

A signal x(t) is anti-symmetric about about vertical axis is said to be odd signal

20. ### WBahn Moderator

Mar 31, 2012
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Okay.

So now, given a signal x(t) (may or may not be odd or even, it's just a signal) defined over all time, what is the mathematical expression that is used to find its average value?