Amplitude Modulation vs Frequency Modulation Essay Example

signal called double sideband amplitude modulation (DSB-AM) was produced.

A sideband is a band of frequencies higher (called upper sideband) or lower (called lower sideband) than the carrier frequencies which is a result of modulation. All forms of modulations produce sidebands. In DSB-AM the carrier and both USB and LSB are present. The power usage in this system proved inefficient and led to the double-sideband suppressed-carrier (DSBSC) signal in which the carrier is removed. For greater efficiency, single-sideband modulation was developed and used in which only a single sideband remained. For digital ommunication, a simple form of AM called continuous wave (CW) operation is used in which the presence or absence of carrier wave represents binary data. The International Telecommunication Union (ITU) designated different types of amplitude modulation in 1982 which include A3E, double sideband full–carrier; R3E, single-sideband reduced-carrier; H3E, single-sideband full-carrier; J3E, single-sideband suppressed-carrier; B8E, independent-sideband emission; C3F, vestigial-sideband and Lincompex, linked compressor and expander.

FM radio characteristics and services include pre-emphasis and de-emphasis, stereophonic FM sound, Quadraphonic sound, Dolby FM and other subcarrier services. Pre-emphasis and de-emphasis are processes that require boosting and reducing certain frequencies. This is done to reduce noise at high frequencies. Stereophonic FM radio was developed and formally approved in 1961 in the USA. This uses two or more audio channels independently to produce sound heard from various directions. Quadraphonic is four-channel FM broadcasting. Dolby FM is a noise reduction system used with FM radio, which has not been very successful, commercially.

FM vs. AM The Explanation: FM stands for “frequency modulation” and AM stands for “amplitude modulation,” so it’s not hard to figure out that the distinction is based on the

way a radio wave modulates, or fluctuates. FM waves differ from one another based on frequency, or how many times per second the wave’s current changes direction. AM waves, however, fluctuate based on amplitude, which refers to the specific strength of the signal. All radio waves experience changes in amplitude as they travel, but obviously, if the amplitude isn’t strong enough when it reaches a receiver, you’ll hear static.

And because AM waves depend on specific amplitudes to get a signal, they’re less reliable. This also makes them less valuable, which is why it’s easier for all those farm news enthusiasts and mariachi bands to get one of their own. If you’re wondering about their order, there’s no chicken and egg here: The AM definitely came first. Inventor Reginald Fessenden made the first AM radio broadcast in 1906—presaging those radio preachers by making his first broadcast a reading from the Bible and a live performance of himself playing “O Holy Night” on the violin. And while the medium was most popular from 920 to the advent of FM in the ’50s, AM certainly has its limitations. For one thing, AM travels by sound waves close to the Earth during the day and higher in the sky in the evening, meaning it’s hard to have a large broadcast radius during daylight hours. For another thing, AM signals, unlike FM, are often disrupted by tall buildings—a bigger problem today than in 1920. As for FM, it was invented in 1933 by Edwin Armstrong—but sadly enough, Armstrong never lived to see his invention succeed. Convinced FM had failed, Armstrong committed suicide by jumping out of his window in 1954.

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a few years later, the superior sound quality and general betterness of FM were recognized by the American public, and FM took off, making Armstrong’s widow rich. 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. 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.