Frequency domain

In mathematics, physics, electronics, control systems engineering, and statistics, the frequency domain refers to the analysis of mathematical functions or signals with respect to frequency (and possibly phase), rather than time, as in time series.

A complex valued frequency-domain representation consists of both the magnitude and the phase of a set of sinusoids (or other basis waveforms) at the frequency components of the signal.

A given function or signal can be converted between the time and frequency domains with a pair of mathematical operators called transforms.

A spectrum analyzer is a tool commonly used to visualize electronic signals in the frequency domain.

One of the main reasons for using a frequency-domain representation of a problem is to simplify the mathematical analysis.

In addition, looking at a system from the point of view of frequency can often give an intuitive understanding of the qualitative behavior of the system, and a revealing scientific nomenclature has grown up to describe it, characterizing the behavior of physical systems to time varying inputs using terms such as bandwidth, frequency response, gain, phase shift, resonant frequencies, time constant, resonance width, damping factor, Q factor, harmonics, spectrum, power spectral density, eigenvalues, poles, and zeros.

Frequency Domain Electromagnetic Method (FDEM) as tool to study contamination at the sub-soil layer.