Let’s go back in time to a time before Spotify, Apple Music, and YouTube — to the early twentieth century. It was the era of physicists experimenting with electromagnetic waves and inventors developing the first radio wave receivers. It was the birth of modern AM (amplitude modulation) radio. It has been bringing people together to share news, music, and other broadcasts since its inception.
FM, or frequency modulation, was introduced as an alternative to AM in the 1930s. These two types of radio waves became increasingly popular over time. They are currently the two main types of radio broadcasting services.
AM and FM radio are two sides of the same coin, both of which provide us with hours of entertainment and information. But what distinguishes them? Is one superior to the other? In this article, we’ll look at radio waves and signal modulation, as well as compare AM and FM radio to see how they compare.
AM vs FM Radio: Side-by-Side Comparison
| AM Radio | FM Radio | |
|---|---|---|
| Year Developed | 1906 | 1933 |
| Signal Modulation | Amplitude modulation (AM) | Frequency modulation (FM) |
| Frequency | 535 to 1605 kHz | 88 to 108 MHz |
| Wavelength | Between 600 and 300 meters | Between 3 and 10 meters |
| Range | Longer range, better for long-distance transmissions, but more prone to interference | Shorter range, preferred choice for local radio stations, and less prone to interference |
| Signal Quality | Lower quality | Higher quality |
| Resistance to Interference | More susceptible to interference | Less susceptible to interference |
AM vs FM Radio: What’s the Difference?
Now that we’ve covered the broad strokes of their differences, let’s dig deeper into each one individually to better understand them.
Signal Modulation
The primary distinction between AM and FM is in how information is encoded onto electromagnetic signals via a process known as modulation. AM radio transmits audio signals by varying the amplitude of a radio wave. The audio signal is superimposed on the amplitude of the carrier wave, causing the wave’s strength to fluctuate up and down.
These fluctuations are then picked up by the receiver and converted back into an audio signal. Although AM radio waves can travel long distances, they are more susceptible to noise and interference, which can cause static and signal distortion.
FM radio, on the other hand, transmits audio signals by varying the frequency of the radio wave. When information is superimposed on the frequency of a carrier wave, the frequency of the wave fluctuates accordingly. FM radio waves carry more information and have better signal quality than AM radio waves.
Frequency Band
AM waves have a frequency range of 535 to 1605 kHz, while FM waves have a frequency range of 88 to 108 MHz. This variation indicates that AM waves are a better choice for long-distance communication than FM waves, which have a shorter range.
The reason for this difference is that lower frequencies have longer wavelengths and can more effectively penetrate buildings, mountains, and other obstacles.
AM waves, on the other hand, aren’t always the better option. Because of their lower frequency, they are more susceptible to interference and noise from other electronic devices, such as power lines, motors, and other electrical equipment. This interference can be aggravating for listeners, particularly in densely populated urban areas with a high concentration of electronic devices.
FM waves, on the other hand, operate at higher frequencies, resulting in shorter wavelengths and more stable signals. As a result, FM radio stations can broadcast higher-quality, clearer sound and are less susceptible to interference, making them the preferred option for local radio stations.
Wavelength
As previously stated, the wavelengths of AM and FM waves differ, and this has a significant impact on signal quality and reliability. The length of a wave is simply the distance between two corresponding points on adjacent waves, such as the distance between the waves’ peaks and troughs.
The wavelength of AM waves is much longer than that of FM waves, measuring between 600 and 300 meters. This means that the waves have a lower frequency and can carry less information.
FM waves, on the other hand, have much shorter wavelengths, ranging from 3 to 10 meters. This allows them to carry more information, resulting in higher sound/signal quality.
Range
The wavelength of a radio wave determines its range. AM waves, with wavelengths ranging from 600 to 300 meters, can travel further without being attenuated (losing signal strength). As a result, AM radio is a better option for long-distance transmissions. This can be beneficial for rural listeners who may not have access to other forms of media.
Because of the ionosphere’s reflection, AM waves travel further. Unlike FM waves, which dissipate into space, this allows them to travel around the world without the use of boosters. However, because of the increased range, AM radio is more susceptible to interference from other devices, such as other transmitters and power lines.
Signal Quality
When comparing AM vs FM radio in terms of signal quality, FM typically comes out on top. This is due to FM radio’s higher bandwidth, which allows it to transmit a wider range of frequencies.
Because of the increased bandwidth, more information can be carried, resulting in clearer and more detailed sound. Because FM radio can transmit a wider range of frequencies, it can pick up on more subtle nuances in music and speech, resulting in more accurate sound reproduction.
AM radio, on the other hand, has a lower bandwidth, limiting its ability to transmit a wide range of frequencies. As a result, the sound quality is less detailed and clear, which is why AM radio is commonly used for talk radio and news broadcasts.
Despite its limitations, AM radio remains a popular medium for long-distance communication, particularly in rural areas where FM radio signals may be unavailable.
It’s also worth noting that the strength of the input signal, the quality of the equipment used to transmit and receive the signal, and the environment in which the signal is transmitted can all have an impact on the quality of the signal received.
Resistance to Interference
When it comes to interference resistance, FM radio outperforms AM radio. This is because the frequency modulation of FM radio is less susceptible to interference than the amplitude modulation of AM radio.
In layman’s terms, FM radio’s method of encoding information into the frequency of the carrier wave means that any interference in the amplitude of the wave will not affect the transmitted information.
As a result, the sound quality is clearer and more consistent, with less distortion and noise. AM radio, on the other hand, encodes information into the carrier wave’s amplitude, making it more susceptible to interference. Static, crackling, and other unwanted sounds can result, interfering with the listening experience.
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AM vs FM Radio: Where Is Each Type Applied?
As we’ve seen, AM and FM have distinct characteristics that make one more suitable for certain types of content than the other. Because of its greater range and lower susceptibility to interference, AM radio has long been the preferred medium for talk radio and news broadcasts.
This is especially useful for emergency announcements and public service messages that must reach a large number of people quickly. Because of ionosphere reflection, AM waves travel further than FM waves.
This enables them to reach further away locations without the use of terrestrial boosters. Furthermore, AM waves can easily pass through many physical obstacles, making them ideal for emergency communication. AM radio is also more widely available, with a greater selection of low-cost receivers.
FM radio, on the other hand, has long been the preferred medium for music broadcasts due to its lower susceptibility to noise and superior sound quality, which is critical when fidelity and clarity are critical to the end listener’s experience.
The distinction between AM and FM radio has evolved over time, with most radio stations now using FM for talk shows and news programs due to technological advancements that have improved sound quality.
Nonetheless, AM and FM radio are still widely used in some areas, with AM serving as the primary source for talk radio and news, and FM serving as the primary source for music broadcasts.
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AM vs FM Radio: 6 Must-Know Facts
- In 1864, James Clerk Maxwell predicted the existence of radio waves, which Heinrich Hertz discovered in 1888. In recognition of his contributions, Hertz had the frequency unit named after him.
- Both types of radios use electromagnetic radiation, which travels at the speed of light through air (300 million meters per second).
- Reginald Fessenden was the first person to broadcast an audio signal using amplitude modulation (AM) on Christmas Eve 1906 from Brant Rock Massachusetts.
- Edwin Armstrong demonstrated wide-band FM in 1933 with a prototype transmitter he built himself out of spare parts he found lying around his Columbia University lab.
- To receive an AM signal, you must have an antenna that can pick up long-wave signals; however, to receive an FM signal, you must have an antenna that can pick up short-wave signals or use a satellite dish if you use satellite radio services such as SiriusXM.
- Consumer-grade walkie-talkies typically use amplitude modulation (AM), whereas professional-grade walkie-talkies typically use narrow-band frequency modulation (FM).
AM vs FM Radio: Which One Is Better?
When it comes down to it, whether to use AM or FM radio is usually determined by the situation at hand.
AM radio is typically the better choice for long-distance communication because it can travel farther and penetrate walls and other obstacles more effectively. Due to its lower bandwidth, however, it is more susceptible to interference from other signals, resulting in static and distortion.
FM radio, on the other hand, is the preferred choice for local radio stations because it provides higher quality sound and is less affected by interference. However, because of its shorter wavelength, it is less suitable for long-distance communication.
Finally, the decision between AM and FM radio comes down to the broadcaster’s and intended listener’s needs, as well as the environment in which it is used.
FAQs
What’s the main advantage of using AM radio for communication?
AM has a greater range than FM, is less expensive and simpler to use, and can be used effectively in areas with many obstacles, such as mountainous terrain or dense foliage.
What are the advantages of using FM over AM radio?
The main advantage of FM radio waves over AM waves is that they have a wider bandwidth, which allows them to carry more data and produces better sound quality. Furthermore, FM waves are less susceptible to interference and noise, making them more dependable.
Are AM radios still in use?
Yes, many parts of the world still use AM radio waves. Because of their lower frequency and longer wavelength, they are frequently used for long-distance communication.
