Frequency meter
Frequency meters are measuring devices for determining the frequency of an electrical alternating voltage. Depending on the type, it can be used to measure sinusoidal alternating voltages or rectangular signals (e.g. breakover oscillations or pulse trains).
Types
- Digital frequency counter - electronic measuring device
- Pointer frequency meter - rotary pointer instruments, analog frequency meters based on the principle of voltage measurement on a frequency-dependent voltage divider
- Tongue frequency meter - electromagnetically coupled measuring device (for approx. 25 ... 400 Hz)
- Wave meter - determination of very high frequencies in the microwave range based on their wavelength
- Dipmeter - based on the resonance and superposition principle
- Absorption frequency meter - after the resonance operation
Analog frequency meters are only suitable for determining frequencies up to around 1 MHz, since parasitic component properties increasingly play a role at higher frequencies. For frequencies up to over 1 GHz, however, digital frequency meters based on the counting principle are predominantly used today. These do not have any problems with irregular pulse trains either, since they determine the number of zero crossings in a certain period of time, while the analog measuring methods only work with sinusoidal signals or defined pulse shapes without display errors.
Tongue frequency meters are also suitable for measuring acoustic vibrations by stimulating them directly with structure-borne sound rather than electromagnetically.
Wave meters register interferences in a waveguide or a piece of coaxial line, in which a short-circuit slide can be moved. Half the wavelength can be read off directly on a metric scale by looking for two neighboring minima or maxima. The frequency can also be calculated from the phase velocity .
Frequency meters that record airborne sound with a microphone are used as tuners by musicians.