Impulse Response

The output signal h(t) (or h[n] in discrete time) produced by a system in response to a unit impulse (Dirac delta or Kronecker delta) input; for LTI systems it is the system's time-domain kernel that determines outputs by convolution.

The time‑domain function h(t) of a linear time‑invariant (LTI) system that equals the output produced when the input is an ideal unit impulse δ(t); for LTI systems the output y(t) to any input x(t) equals the convolution y(t)=x(t)*h(t). In communications, the impulse response summarizes delay, amplitude scaling and phase effects (including multipath components) experienced by transmitted pulses.