Stay Tuned

As you probably know, theres two major way to transmit information through radio wave. Amplitude modulation (AM) and frequency modulation (FM). (Theres also Phase modulation PM, but i dont think its ever been used).

Amplitude modulation transmits sound waves by adjusting the amplitude of the radio wave, or carrier wave to match the changes in the sound. In AM transmissions, the frequency is kept constant and the amplitude is adjusted. If radio was broadcast using visible light, this would mean that each radio signal would have its own color, and the signal would be broadcast by brightening and dimming the light.

Commercial AM radio stations transmit at set frequencies between 535 kHz and 1,605 kHz. The good thing about transmitting at these frequencies is that they can be reflected and refracted by the layer of the atmosphere called the ionosphere. This means that AM radio can be heard very far away, even over mountains. The problem with AM radio, though, is that interference from things like lightning, machinery, and UFO?s affect the amplitude of the signal. This is why during thunderstorms and alien attacks, AM radio sucks even worse than it usually does.

Frequency modulation transmits sound by adjusting the frequency of the radio wave. The mechanics behind frequency modulation are more difficult, but the main point is that the amplitude of the radio wave stays constant, while the frequency fluctuates around a basic carrier wave. This is like keeping a light at a constant brightness, but changing the color to transmit information.

Commercial FM stations transmit between 88 MHz and 108 MHz, frequencies which aren?t reflected by the ionosphere. This means that FM stations need to be placed in high spots so that they can cover more area. However, FM isn?t affected by changes in amplitude, so the things that interfere with AM signals don?t affect FM signals. Unfortunately, controlling annoying passengers who fiddle with your car radio is still beyond the power of modern science.