multifrekvens

Multifrekvens, literally "multiple frequencies," is a property of a signal or system that involves more than one frequency component. In physics and engineering it usually refers to signals that can be represented as a sum of sinusoidal terms with different frequencies, amplitudes and phases. Through Fourier analysis a multifrekvens signal in the time domain corresponds to a spectrum with multiple peaks in the frequency domain.

In practice a multifrekvens signal is created by superposing several tones or by modulating a carrier with several subcarriers. The resulting waveform may be described by a Fourier series or Fourier transform, and its instantaneous characteristics can be reconstructed by summing the components. When analyzing such signals, practitioners examine the amplitude and phase of each frequency component, and the overall bandwidth spans from the lowest to the highest significant frequency present.

Applications of multifrekvens are wide. In telecommunications, multifrekvens or multi-carrier modulation (for example OFDM) uses many closely spaced carriers to increase data throughput. In audio and music production, layering tones creates complex timbres. In imaging and sensing, multifrekvens excitation (or multispectral/multifrequency illumination) may improve resolution or contrast. In nondestructive testing and vibration analysis, multiple excitation frequencies reveal material properties.

Challenges include managing spectral interference, accurately estimating components in the presence of noise, and ensuring sufficient sampling rate and dynamic range. Hardware needs to cover the full bandwidth and avoid distortion; windowing and spectral leakage must be handled in analysis.

The term is used in Norwegian contexts as multifrekvens or flerfrekvens. See also Fourier transform, multitone signals, OFDM, multiplexing.