why impulse response !!

[Hassan92]

Hi all , i want to ask why we use always the impulse function to find the transfer function of the system , what is the properties that impulse has to became the base that we stand up on it to see if the system is good or not ?

 

[MahmoudHassan]

because if you tried to find the Fourier transform of an impulse you will find that it equals to one
what ever frequency the amplitude is one

now suppose that we have system and we need to know what is the effect on an input signal ? what is the frequency response of this system
simply we test it using impulse signal and the output response will be resulting from the system not from the test signal which is an impulse that has amplitude of one at any frequency
so impulse is used to test frequency response

 

[emresel]

Another approximation is in time domain.
You can write any continous time domain signal as sum of impulse/delta function (sifting integral).
Here on page 5, you can find intuitive explanation.
Hence if you know impulse response of the system, then you can find the response to any desired continous signal (convolution).