Main Differences Between AM And FM

If you were someone who still loves to hear the radio the old fashion way, then you will come across the word AM or FM. We will commonly choose the FM frequency over AM if we were to listen to our favorite radio station but do you also know how the AM frequency functions?

We might be wondering what are the differences between the two radio frequencies? Which one is much better than the other and why do certain countries prefer to use FM over AM?

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One time ago, many people were using the radio instead of smartphones and tablets to get instant news and the latest music. This was all done over the AM radio frequency. The introduction of the FM radio frequency for commercial news made a big change in this industry.

The term FM is very synonymous with something that plays music and sometimes people get confused over the word FM with devices that plays music over the radio frequency.

What is Modulation?

In radio communication, the radio signal will be demodulated so that it can be transmitted to a far distance. In simpler terms, this means that the radio signal (or input signal) which is the signal carrying the audio information is added to the carrying signal.

Unlike radio signals (usually with a very low frequency), the carrying signal has a constant amplitude and frequency which is the shape of the constant wave that helps carry the radio signal at a far distance.

The process of mounting the original signal to the carrying wave is called modulation.

Analog modulation can be found in three types: amplitude modulation, frequency modulation, and phase modulation. To understand the difference between amplitude modulation(AM) and frequency modulation(FM) shall be discussed below.

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What is Amplitude Modulation(AM)?

To fully understand in detail regarding this matter, it is crucial that we have a fundamental knowledge of how radio produces sound from the start.

Every radio station will emit what is known as a carrying wave or signal wave which is basically a stable electromagnetic wave similar to unchanged frequency and amplitude.

For instance, when the DJ starts playing a song at the radio station or other forms of sound, the sound wave will be changed to an electric signal that moves from the radio antenna and through the carrying wave.

The radio will then change it again into a sound wave that will be emitted by your sound system. When the carrying wave sends the signal, it will change from one of the two ways, FM or AM.

If it is an AM radio station, the carrying wave amplitude(height of the wave) will be manipulated based on the signal. This is what is known as amplitude modulation(AM).

What is Frequency Modulation(FM)?

For FM radio stations, the amplitude remains the same whereas the frequency (referring to the number of waves) will change.

FM in general is considered much better than AM. When a random electrical signal disturbs the carrying wave, this will affect the amplitude. Since the FM-carrying wave does not send a signal through amplitude, this will not affect the quality of the FM radio station.

But changing the AM amplitude carrying wave will disrupt the data that are being transmitted. This is why an AM radio station will sound more static compared to an FM.

FM radios also air a wider range of frequencies known as bandwidth. This means that it is capable of handling more feel and variations in the sounds produced. If you were to listen to any kind of music with less disruption, it will be best heard on an FM radio station.

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Uniqueness and Advantageous of AM

Despite FM radio generally being much better than AM,  there are a few advantages of using AM.

The length of the wave(the distance between one peak of the wave to another) is far much longer than the ones of FM. This ultimately helps the signal wave to travel much farther and remain intact when passing through obstacles such as buildings or mountains.

If you wish to air to as many people as possible, FM radio might be your best bet. Have you ever thought about why you cannot hear some of your favorite radio stations as you travel further to another state?

This is because an FM wave has a smaller range of geographical coverage whereas an AM wave has a wide range of coverage and due to that, it can still be heard despite going further to secluded areas.

This is one of the reasons why news stations will use AM through FM since they want the information to reach a broader range of audience even if the quality is not at its best.

When you talk about the cost, the required infrastructure for FM is far more expensive than AM. Since the AM uses inferior technology, it will depend on less complex tools that cost less to send the signals.

Source:

• Letter.ly

• PBS

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