Techniques for Measuring Frequency Response

Frequency response can be measured using single-tone, stepped swept-sine, continuous swept-sine, and broadband methods.

The following table lists the basic features of four techniques for measuring frequency response.

Table 11. Frequency Response Measurement Techniques
Single-Tone Stepped Swept-Sine Continuous Swept-Sine Broadband
  • Pure-tone excitation
  • Arbitrary test frequencies
  • Single-point spectral resolution
  • Optimal dynamic range
  • Simple and simultaneous measurement of linear response, harmonic distortion, and noise
  • Stepped-sine excitation
  • Arbitrary test frequencies
  • Test time dominated by low-frequency test points
  • Can optimize dynamic range by using custom amplitudes
  • Simultaneous measurement of linear response and harmonic distortion
  • Stepped-sine excitation
  • Arbitrary test frequencies
  • Test time dominated by low-frequency test points
  • Can optimize dynamic range by using custom amplitudes
  • Simultaneous measurement of linear response and harmonic distortion
  • Broadband excitation (chirp, noise, and impulse)
  • Arbitrary frequency distribution of excitation
  • Test time dominated by required frequency resolution and averaging
  • Signals with high crest factors sacrifice dynamic range
  • Simultaneous measurement of linear response over the entire frequency spectrum