What is impulse response?

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saif haider

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what is impulse response

impulse response is usually used in filter and for convolution but i always find it difficult to explain my self what is this and how does it help.
my question what is practical meaning of impulse response, either it an equation or characteristic of a system in response to input.
 

what is impulse response?

Impulse response is the response of a system to a unit impulse at its input.

Any signal can be considered(approximated) as a stream of impulses (These impulses will be immeasurably close to each other in continuous signals, and will be 1 sample apart for discrete signals). These are not unit impulses. (they have magnitude not necessarily 1). So the response of the system to this impulse should be a scaled form of 'unit impulse response'.

So the output of the system for a certain signal can be considered as the superposition of impulse response due to all the impulses in the input signal. This process of scaling the unit impulse response according to the i/p signal values and adding them all is convolution.

Jacob
 
what is impulse response

Impulse response is response of system when input is provided to it is impulse. if u want to know more then plz proceed this talk,if u've any confusion then reply
 

what is impulse response?


Impulse includes 1,3,5,7......order harmonic, in other word, it covers all the frequency band form 1th order to ∞,
So its purpose is to test the stablity of circuit by transient response.

it is very useful.
 

what is impulse response

Yet another explanation: The impulse response function is the inverse Laplace transform of the system transfer function H(s).
 

unit impulse input

thx nitrojacob for brief reply but would u gave me an easy explanation for this line especially SUPERPOSITION
"So the output of the system for a certain signal can be considered as the superposition of impulse response due to all the impulses in the input signal."
 

what is impulse response function

Think of it from a system perspective. Lets look at an airplane.
Sitting at the controls, a test pilot will get to a smooth level flight. Then they will push the flight stick all the way forward, then bring it all the way back to center position, as fast as possible.
They then see what the planes response is. Some will just drop in altitude, then level off. Some will start to dive and keep diving at a constant rate, and some (OH NO!) will start to dive faster and faster!

So knowing what the impulse response is, goes a long way in telling the characteristics of a system.

A designer should know what the impulse response should be, then design the system to it.

Hope this helps.

Red
 
what is a impulse response

Consider this example.

Your friend needs capital to start a business. He offers you a scheme, in which you will lend him some amount of money.

If you give him 1$ on day1, he will return
0.5$ on day 2
0.25$ on day 3
0.25$ on day 4
and 0.10$ on day5. (This .1$ is the interest for your money)

Let you be investing 50$ on day 1, 30$ on day 2 and 75 $ on day 3, how will you calculate the amount that your friend should return to you each day?

This exactly is what is done with impulse response.
Considering th offer, the 1$ specified is the unit impulse. How your friend will return you each dollar is unit impulse response.

Your input signal is x[n]=(50$, 30$,75$)
What you have calculated as return to you each day is y[n]=covolution(x[n],unit impulse response)

Hope this helped you
 
unit impulse response

the plane was a very good example to understand the practical meaning of the impulse response of a system . first you have to understand what is the input of the system for example for the plane the input was the movement of the stick. and the output was the reaction of the plane to that stick movement. the response of a system to a very abrupt input with a very abrupt decay of the input is called impulse response. it shows the agility and many other factors for a system. system can be anything like plane, a mechanical or an electrical filter, a car, etc.
 

meaning of impulse response

It is output of the system when an impulse is applied to the input, it is denoted by h[n].

There are two types of impulse responce

FIR
IIR
 

impulse input

hi saif.......

i think all these people should tell you in urdu. or some examples from your personal life.........or tell you a long story again and again....then you will understand impulse response.... hopefully....

superposition mean???? you dont know? If I lay upon you....or behind you...that means i m super imposed on you.....or you can say in technical language that...one after the other.....and so on...is called superposition....

hope that answers the question.........

I really appreciate the efforst of all these people who really managed time to answer you so devotedly....may you got it
 

The definition of impulse is given by the function

δ(t)= { 1 , t=0 | 0 , otherwise }

When you want to analyze a system from its frequency, you transform the time domain to the frequency.

First we find the transfer function of the system, so we spent this function to the frequency domain (Fourier transform).
The system input and output are related by Y(jW)=H(jW)*X(jW)
Where Y(jW) is the output, X(jW) is the input and H(jW) is our transfer function.
To analyze how our system behaves in frequency, we take as input X(jW) a unit impulse.

Applying the Fourier transform for δ(t) we have δ(jW)=1

Y(jW)=H(jW)*1 ---> Y(jW)=H(jW)

Thus our output does not change with the entry of a unit impulse, and we can analize our system in two different domains.
This is usually used for filter projects. However, there are several other applications for this tool.
 

i though, firstly, you should approach the definition of impulse response in analog system.
 

It's show the exiting of input signal and about delay time.
 

if you have a system and u don't know the properties of that system ....then to check the response of that system...for this u should give an impulse signal as a input ...after passing through the system the impulse will be changed through which u can find out the response of that system and the output signal is the impulse response of that system.
 

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