The value of many physical quantities is determined via frequency measurement, which is of essential importance for electrical measurement technology. This applies, for example, to speed, length and velocity measurement as well as to communication technology. The measuring instruments used for frequency measurement can measure frequencies of sinusoidal alternating voltages as well as rectangular signals (tilt oscillations, pulse trains).
In physics and electrical engineering, frequency is generally defined as the number of oscillations of a periodic process per unit of time. In modern measurement technology, common methods of frequency measurement include the counting method, the fast Fourier transformation (FFT) and an electronic mix with reference frequency. Accordingly, digital frequency counters, pointer frequency meters, reed frequency meters, wave meters, dip meters and absorption frequency meters are used as measuring instruments for frequency measurement.