What is FM ?

A quasar is an incredibly bright galactic core powered by a supermassive black hole.

A quasar is an incredibly bright galactic core powered by a supermassive black hole.

Quasars radiate energy broadly across the EM spectrum, but the name comes from the fact that the first quasars to be identified emit mostly radio energy. Quasars are very energetic; some emit 1,000 times as much energy as the entire Milky Way.

What Are Radio Waves?

You're probably familiar with AM, which stands for Amplitude Modulation, and FM, which stands for Frequency Modulation.

Both AM and FM radio programs are transmitted over the air via radio waves, which are part of a broad range of electromagnetic waves

Electromagnetic waves are all around us everywhere in different frequencies. Radio waves exhibit similar properties to that of light waves (e.g. reflection, polarization, diffraction, refraction), but exist at a frequency that our eyes

which is the electrical power used to run pretty much every appliance and/or technology in our homes and lives – from washing machines to televisions to our mobile devices. In the United States, alternating current operates at 120 volts at 60 Hz.

This means that the current alternates (changes direction) in the wire 60 times per second. Other countries use 50 Hz as the standard. Although both 50 and 60 Hz are considered relatively low frequencies, the alternating currents still generate a basic level of electromagnetic radiation (EMR). This means that some of the electric energy escapes the wire and is transmitted into the air.

This means that the current alternates (changes direction) in the wire 60 times per second. Other countries use 50 Hz as the standard. Although both 50 and 60 Hz are considered relatively low frequencies, the alternating currents still generate a basic level of electromagnetic radiation (EMR). This means that some of the electric energy escapes the wire and is transmitted into the air.

The higher the frequency of the electricity, the more energy that manages to escape the wire out into open space. Thus, electromagnetic radiation can be loosely described as 'electricity in the air'.

Electricity in the air is nothing but random noise. To be turned into useful signals that transmit information (music or voice) it must first be modulated, and modulation is the basis for AM and FM radio signals.

Electricity in the air is nothing but random noise. To be turned into useful signals that transmit information (music or voice) it must first be modulated, and modulation is the basis for AM and FM radio signals.

That's how the terms AM and FM originated since AM stands for amplitude modulation and FM stands for frequency modulation.

Another word for modulation is change. The electromagnetic radiation must be modulated or changed in order to be useful as a radio transmission.

The electromagnetic radiation must be modulated or changed in order to be useful as a radio transmission. Without modulation, no information would be carried by a radio signal.

Modulation is an easy concept to understand, especially since it's all around us. Our sense of vision is a good example to describe how modulation works.

A blank piece of paper in your hand is useless until it becomes modulated or changed in some meaningful way. Someone would have to write or draw on the paper in order to communicate useful information.

When it comes to radio broadcasts, the electromagnetic radiation (electricity in the air) must be modulated with the desired information to send.

AM Radio Broadcasts

AM radio uses amplitude modulation and is the simplest form of radio broadcast.

To understand amplitude modulation, consider a steady signal (or wave) broadcasting at 1000 kHz on the AM band.

The amplitude (or height) of the constant signal is unchanged or un-modulated, thus containing no useful information.

This steady signal produces only noise until it is modulated with information, such as voice or music.

The combination of the two results in a change to the amplitude strength of the steady signal, which increases and decreases in direct proportion to the information.