Figure 9 13 shows the same system response in presence of a disturbance. As expected, there is no effect on the steady state controller effectiveness in reducing the effect of the disturbance, but the transient effect of the disturbance signal is reduced fewer oscillations. Figure 9 14 shows how the changing value of the derivative time constant (the same as derivative. Gain ) affects the system closed loop response. Derivative time constant (or derivative gain) the stronger the derivative effect hence fewer oscillations. Figure 9 12 closed loop step response of the example system under. Figure 9 13 closed loop step response under pd control effect of. Figure 9 14 closed loop step response under pd control effect of. Changing derivative time constant 9. 3. 1 proportional + derivative control in presence of noise. Let"s consider now the effect of using a derivative control on the system closed loop frequency response specifically, its bandwidth.