Question 2.38: Impulse response of a system...

It is not possible to produce an impulse function electronically as no practical signal can have an infinite height. However, an approximation to an impulse function is often used, consisting of a pulse with a large voltage, V, and short duration, T. The strength ofsuch an impulse is VT. When this pulse signal is injected into a system the output obtained is known as the impulse response of the system.
The approximation is valid provided the width of the pulse is an order of magnitude less than the fastest time constant in the system. If the value of T required is small in order to satisfy this constraint, then the value of V may need to be large to achieve the correct impulse strength, VT. Often this can rule out its use for many systems as the value of V is large enough to distort the system characteristics.