3.4.3 Responses of measuring system to typical excitations The first-order system H( +1 its impulse response h(t) (345) where t△ time constant h (t) Fig 3. 18 Impulse response of first-order systemThe first-order system its impulse response h(t) where time constant. 3.4.3 Responses of measuring system to typical excitations ( ) 1 1 + = s H s  ( )   t h t e − = 1 (3.45)   Fig. 3.18 Impulse response of first-order system