impulse invariance?

Question

impulse invariance what's it's basis?

what is impulse invariance methods basis?

thank you

Answer 1

Impulse invariance is a technique used to transform the response of a continuous time filter into a sampled (discrete) time digital filter. It's one of the methods used to 'approximate' the required coefficients of a digital filter by 'sampling' the impulse response of an analog filter and then using those values as the coefficients for the sampled data filter.

Why use an 'approximation'? Simple. Nobody knows how to go from a direct analog transfer function to a discrete time transfer function. That's something that most of the textbooks won't say specifically, but it's the truth. Even the z-transform is an approximation (since it looses all of the higher order Fourier components greater than the Nyquist limit)


Doug