The shape of the magnitude and phase responses of a filter impacts how signals look in the time domain. The step response of a filter is typically used to identify the behavior of a filter in the time domain.

Three important factors of the filter step response are group delay, rise time, and overshoot/undershoot. The three filters differ in step response across signals in the transition band:

  • Brickwall—Has the longest group delay. The output signal shows overshoot and undershoot.
  • Butterworth—Has a shorter group delay and the longest rise time. The output signal shows overshoot.
  • Comb—Has the shortest group delay and good rise time. The output signal does not show overshoot or undershoot.
Figure 36. Comparing Typical Step Response of FieldDAQ Filters


Refer to the FD-11634 Specifications for details on the amount of variation in the response you can expect for different input frequency ranges.