In order to understand the particulars of FM radio, we must start with the basic science behind radio technology. Radio waves are capable of transmitting more than just sound. They are the basis for all modern wireless technology, including cell phones and wireless Internet. A radio works by converting data (of any kind) into a sine wave. A sine wave is an electronic signal based on oscillating (changing between two points) electrical current. The sine wave moves repeatedly between two points of high and low voltage, and this change is known as the wave's amplitude.

These electrical currents will naturally affect any conductive material in their vicinity because of the motion of electrons in all directions. This phenomenon is boosted with additional electricity in order to create radio transmission.

Sine Waves and Frequency
The speed at which a sine wave oscillates is known as the wave's frequency. In order to distinguish one wave from another, each data stream's sine wave has its own frequency.

In order to locate a particular signal being transmitted, any signal-receiving device must be calibrated to pick up a particular speed of sine wave. Each particular wave will be given its own place on the radio dial, and these are the numbers we use to identify radio stations. The device which filters out all sine waves except the one the listener has programmed is called the tuner.

Encoding Information
A sine wave which is sent over radio does not carry any information on its own. In order to transmit data, the data itself must also be converted into sine form, then the data sine wave must be attached to the signal sine wave. This can be done by altering the amplitude (amplitude modulation, or AM) or by altering the frequency (frequency modulation, or FM).

Frequency Modulation
FM radio is a method of adding more frequencies to the radio signal which is attached to carrier wave. These frequencies create a higher quality, higher fidelity audio through the reduction of static and interference. This is because static is generally created by naturally occurring phenomena (such as lightning), creating low-frequency sine waves which an AM receiver will try to pick up as signal.

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How Do FM Radiowaves Work?

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