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No, it is definitely not relative to audio. Sound waves and radio waves are of completely different carriers. The reference medium frequency band in electromag
by daveguy 9y ago
No, it is definitely not relative to audio. Sound waves and radio waves are of completely different carriers.
The reference medium frequency band in electromagnetic (EM) is based on the original AM broadcast frequency ranges (first time broadcasts could be separated into distinct frequency bands). Medium frequency (MF) is just what we started with broadcasts and the ranges expanded around that.
Audio and Radio frequency ranges are completely unrelated.
Radio is electromagnetic and audio is air pressure. As far as human hearing is concerned there is only one "band" 20 Hz to 20kHz with greatest sensitivity from 1kHz to 4kHz. That is air pressure wave propagation and has nothing to do with radio frequencies and propagation of electromagnetic waves in the ULF to VLF ranges.
- kazinator 9y ago> Sound waves and radio waves are of completely different carriers. (ITYM "media"; a carrier is a waveform onto which a signal is imprinted.) In an electronic circuit it's just frequency, whether the waveform came from a microphone, or from a radio-frequency oscillator. When you mix audio into a carrier to produce a radio signal, it's all just math functions realized in the same medium: the medium of voltage/current changes versus time. In radio, audio frequencies that were once carried through the air are imprinted, via electronics, onto radio frequencies. For instance, a 500 Hz audio tone modulating a 700 kHz AM carrier creates 700.5 kHz and 699.5 kHz side bands (chopped to just one side band with SSB (single side band) encoding). The fact that there had been a sound wave moving through the air is now imprinted in the radio wave medium. "Low frequency" in radio basically starts in a range that is outside of radio, yet high enough to be usable for carrying audio signals.