Difference between AM and FM

Difference between AM and FM

In 1905, radio broadcasting was more experiential than commercial, not until in 1920. In the ancient times of broadcasting, most radio stations used long-wave, short-wave, and medium-wave bands for broadcasting. But over time, with various upgrades, radio broadcasting has incorporated extremely high frequency and ultra-high frequency.

There are different modes of radio broadcast; they include amplitude modulation and frequency modulation. They are similar but have differentiating factors about them. These two modes can easily transmit information packaged as electromagnetic waves.


One main differentiating factor about them is that amplitude modulation will modulate the amplitude of any signal and keep the frequency at constant. On the other side, frequency modulation will modulate the frequency of a signal and keep the amplitude constant.

Amplitude modulation was created way before frequency modulation. FM was like an upgrade from the AM. If you compare signal clarity between the two modes, you’ll notice that FM is on the high end.

What is AM (Amplitude Modulation)?

Amplitude modulation is a process where radio waves are transmitted when you modulate the amplitude. AM is used as a form of electronic communication. Amplitude modulation is the oldest form of transmitting information signals for radio broadcast.

It is important to note that the carrier will not vary, but the modulating information changes it for it to get transmitted. AM is the most easy version of broadcast for transmission and reception to implement compared with the rest of other radio broadcasts. It will use low bandwidth.

Setting up an AM is not expensive, making it easier to go to radio broadcasts for long-distance transmission. The transmitter and the receiver components are not complex, and anyone can easily hack them. This makes it very economical.

You have to note that this form of transmission will consume huge amounts of power and reception. Sometimes it would require you to have high signals like that of a frequency modulation. The signal is somewhat poor as it can be interfered with by noises, but it is highly sought after since you can transmit long-distance.

AM radio stations can transmit at a frequency of up to 15 KHz, but it is turned to a frequency of 5 KHz or less. AM signals are always affected by external factors. Support and storms are some of the external factors that affect its signal.

What is FM (Frequency Modulation)?

Frequency Modulation is a way of transmitting radio wave signals with frequency. It is the effective mode from the two that you can use to transmit radio signal waves and reception. The amplitude must also be in frequency.

It is the most sought-after transmission mode because of its high-quality signals. Its transmitter and receptors are complex, a reason why they are very expensive. Additionally, operating the FM is not easy, and the signals cannot travel to long distances.

FM works because it needs various radio stations in between them to receive and reproduce data at a small distance. An advantage over the AM is that it does not consume a lot of power. There’s no geographical interference between stations, even with other man-made towers like cell phone towers, the signal maintains its h2 stature.

However, its transmission and reception would require high bandwidth. It is a premium broadcasting technology that requires its bandwidth to be high to get clear and quality sound.

It was initially created in the 1990s to provide great music over the radio. The transmitters work to detect the right signal and weed out all unwanted signals, ensuring that it is picture-perfect.

Difference between AM and FM

  • The main distinguishing factor is the disturbest factor. For instance, AM is noisy and is affected by external environmental factors, while FM is clear and disturbance-free and has quality sound.
  • AM is very economical in terms of expenses as its signals can travel over a long distance, and operating the transmissions and receptors is also easy. While FM, you will need various stations in between to transmit to a long distance. FM multiple radio stations to transmit and reproduce.
  • The components of Transmitters and receptors of an Amplitude Modulation are not complex and are easy to operate, whereas the components of transmitters and receptors of frequency modulation are complex and hard to hack.
  • When we look at the technical part of these two types of transmission modes, we find that AM is modulated, keeping the same phase and frequency constant. While FM is modulated, keeping the amplitude and phase constant.
  • In FM, it requires a high bandwidth, whereas AM will require a lower bandwidth.


These modes of transmission have unique features that make them a to-go mode. The mode of transmission you choose will depend on your need at a particular time. If you are going for a speech broadcast, then Amplitude Modulation is the best to go for since it will reach a larger audience.

On the other side, FM is used for transmitting music and broadcast. If you wish to select an affordable option, then AM takes the cake hands down. On the other side, FM is chosen because of its large sidebands. The advancement in technology has enabled the radio transmission and reception to become automated.

It has made broadcasting cost-effective and simple. It has made the international audience to tune in and listen to the broadcasting radio. The modes of transmission were discovered in different eras and made to function differently.