Radio explained - the difference between FM and AM

AM vs FM radio

One of the first things that most drivers do when entering their cars is turning on the radio. Many people have their favorite stations, while others constantly look for something new in the ether. This difference in style is common in many countries and just as real as the difference between AM and FM, which most listeners have no idea what it represents. Here are a few facts that will help you understand better the two options on your radio.

What are AM and FM?

To understand what makes AM so different from FM you need to find out what they mean. Both of them are ways of transmitting information through electromagnetic waves. AM stands for amplitude modulation, and it sends messages by changing the signal's amplitude and keeping the frequency constant. On the other hand, FM (frequency modulation) changes the frequency of the signal while maintaining its amplitude constant.

The main contrast between FM and AM

The AM radio was first invented in the United States in the 1870s. It took inventors over 60 years to come up with the FM radio, when Edwin Armstrong perfected it in 1930.

A radio wave transmitted through frequent modulation is changed to emulate the electromagnetic field that it transcends. Its amplitude remains the same the entire way before reaching the receiver, which is the consumer’s radio.

A signal sent through amplitude modulation keeps the same frequency encountered in the magnetic field and oscillates the amplitude of the wave regularly to reach the receiver.

Pros and Cons

Radio stations that use AM to broadcast their transmissions have a poorer sound quality than the ones which use FM. Nevertheless, this technology is cheap and allows the existence of many small radio stations or personal emitters.

The main benefit of listening to FM radio is that you receive almost no interferences with the signal and your favorite songs are not interrupted by the familiar buzz sound. On the other hand, FM signal is impacted by physical barriers, and this is why you lose signal when you drive through a tunnel or when you want to listen to the radio in your cellar.

How frequency influences modulation

Amplitude modulation has a frequency range between 535 and 1705 kHz, and it can transmit 1200 bits of information per second. When you use the AM function on your radio, you can only reach for the closest radio stations, because the bandwidth does not allow you to reach farther emitters.

Frequency modulation is the preferred way of using electromagnetic waves to transmit information because it has a frequency range between 88 and 108MHz. Also, it can send between 1200 and 2400 bits per second.

Complexity issues

AM technology allows many independent radio emitters to reach small audiences without the need for substantial investments. In fact, you can set up your radio station at home, if you want to communicate with the people in the local community. Both the transmitter and the receiver devices require a basic level of complexity.

Emitting in FM demands devices of a higher intricacy, and it can only be achieved with proper investment and voltage adaptors, which makes it difficult for radio enthusiasts to set up their FM station in their attic.