The Difference Between AM and FM

AM and FM are two very popular and very different methods of sending information over the airwaves. AM is amplitude modulation while FM is frequency modulation. But what is modulation? It is the act of modifying a certain aspect of the carrier frequency in accordance to the information being sent. It is then clear that AM modifies the amplitude of the carrier frequency while FM modifies its frequency.

AM is the older an easier of the two technologies to implement. The receiver detects the changes in the carrier frequency’s amplitude and amplifies it to drive a speaker. The simplicity of the technology made it easy to build radio receivers in great quantities. The main problem associated with AM broadcasting is the fact that it is very susceptible to various weather conditions that deteriorate and distort the signal. The simplicity of the design also limits the broadcast to a single audio channel, making it inadequate for stereo sound.

FM is a development over AM broadcasting and it provides a lot of substantial benefits thus it is much more complex compared to AM. The first and most substantial benefit is its ability to send out two channels of information at the same time with the use of advanced algorithms. This allows the station to broadcast left and right audio channels for full stereo sound. Since most environmental factors that distort radio waves only affect its amplitude and not the frequency where FM stores the actual voice signal, the data in the FM signal doesn’t degrade as easily as AM. This also means that FM signal quality doesn’t degrade linearly as you get further from the transmitting station.

Range wise, AM takes the cake with its much greater distance travelled. FM signals usually drop of at around 50 miles from the station, but AM waves can be refracted in the atmosphere resulting in greater range. The range is also one of the reasons why talk radio prefers AM even if the sound quality is not very high.

The advancement in technology also meant that the degree in complexity and price between AM and FM receivers have become moot. Most manufacturers can even manage to place the whole circuitry for both AM and FM inside a single chip, turning them into a package instead of competing against each other.

Summary:
1. AM broadcasting is simpler than FM but the difference in complexity and price are very marginal at present.
2. AM is more prone to signal distortion and degradation compared to FM.
3. FM doesn’t degrade linearly with distance.
4. AM usually broadcasts in mono which makes it sufficient for talk radio.
5. FM can transmit in stereo making it ideal for music.
6. AM has a longer range than FM.

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