Photo: Peter Megyeri
The radio is a perfect example of an old technology that we completely take for granted – do you know how it works or are you just cluelessly upset when all you hear is static? These older technologies are much easier to wrap my head around – if a some guy in the 19th century could figure it out, I should be able to understand the basic idea. I’m not going to focus on how a radio transmitter physically creates the signal or receiver is able to turn it into sound, but rather the basic theory and some interesting things to know.
What is the major difference between AM and FM?
AM stands for amplitude modulation. This means the sound determines the amplitude of the radio wave. FM stands for frequency modulation – the sound alters the frequency of the radio wave. The transmitter is able to turn the sound being created into the appropriate wave. Here is an example of a sound and how it would look as an AM and FM wave:
Source: Berserkerus
Another major difference is that AM radio waves are a much lower frequency than FM. Think of AM having the wavelength of a football field and FM the ball. In reality you can broadcast amplitude modulation or frequency modulation at any frequency, but high quality FM audio must be a high frequency to allow for the differences (or modulation) in frequency.