Stimulus Signal Configuration

Stimulus signals should cover the required frequency range of DUTs. To reduce test time, sweep signals are commonly used as stimulus signals. Sweep signals include continuous frequency sweep signals (also known as chirp signals), stepped frequency sweep signals, and stepped level sweep signals.

For frequency sweep signals, sweeping from high to low frequencies is preferred over sweeping from low to high frequencies because this approach allows a more gradual increase in the power applied to the speaker and decreases the settling time before measurements for each frequency.

The sweeping duration mainly depends on the lowest frequency. The lower the lowest frequency, the longer the sweeping duration. Consider the following factors when setting the sweeping duration:
  • Minimizing the impacts of background noises—Prolong the sweeping duration at lower frequencies where more background noises exist.
  • Saving test time—Set separate sweeping durations for the 1/n octave stepped frequency sweep signal at low and high frequencies.
  • Balancing test efficiency and accuracy—Reduce the sweeping duration step by step when the test results are stable and stop reducing when the results start to deviate.