frequentierespons

Frequentierespons is a term used in signal processing to describe how the output of a system responds to inputs that vary sinusoidally across different frequencies. In linear time-invariant systems, the frequentierespons is represented by a complex function H(ω) = Y(ω)/X(ω), where Y is the output spectrum and X is the input spectrum. The magnitude |H(ω)|, often expressed in decibels, indicates gain or attenuation at each frequency, while the phase ∠H(ω) describes the phase shift introduced by the system.

The time-domain counterpart of the frequentierespons is the impulse response h(t). For LTI systems, H(ω) is the Fourier transform of h(t), and knowledge of either h(t) or H(ω) completely characterizes the system’s linear behavior. Discrete-time systems use H(e^{jω}) as their frequency response.

Measurement and visualization commonly rely on Bode plots, with magnitude in dB and phase in degrees plotted against frequency on logarithmic scales. Practical measurements can be obtained by exciting the device with a sweep or chirp signal and analyzing the output, or by converting a measured impulse response via Fourier transform. Frequency response analysis is widely used in designing and evaluating filters, amplifiers, loudspeakers, microphones, and control systems, as well as in acoustics and room characterization.

Limitations arise when the system is nonlinear, time-varying, or operates outside a linear small-signal regime; in such cases a single frequency response may not fully describe behavior. Real-world measurements also depend on setup factors such as measurement environment, sensor placement, and loading effects, which can colour the observed response.