FM Part 2. AM Vs FM: The Technical Reasons Freq Modulation is Superior. FM Advantage Outweigh AM.
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• Modulation Part 1. Why Modulation is ...
Why Frequency Modulation (FM) is Superior: Key Advantages Over Amplitude Modulation (AM).
Frequency Modulation (FM) is often preferred over Amplitude Modulation (AM) for several reasons, particularly in the context of radio broadcasting and communication systems. Here are the key advantages of FM over AM:
1. Better Signal-to-Noise Ratio (SNR):
FM is less susceptible to amplitude noise and interference, such as static from electrical devices or atmospheric disturbances. Since FM encodes information in the frequency variations rather than the amplitude, amplitude noise can be effectively filtered out at the receiver.
AM, on the other hand, is more prone to noise because it encodes information in the amplitude of the signal, which can be easily affected by interference.
In AM, information is carried in the changes of carrier amplitude.
In FM, information is carried in the changes of carrier frequency, the carrier amplitude carries no information.
At the receiving end of the FM system, only frequency components of the FM signal will be extracted out during demodulation
Any noise that was superimposed on the FM signal has therefore no effect on the recovered modulating signal
2. Improved Sound Quality:
FM provides higher fidelity audio because it has a wider bandwidth, allowing for a greater range of frequencies to be transmitted. This results in better sound quality, especially for music and high-fidelity audio.
AM has a narrower bandwidth, which limits the range of frequencies that can be transmitted, leading to lower audio quality, particularly for music.
3. Less Susceptible to Signal Strength Variations:
FM signals are less affected by variations in signal strength, which can occur due to changes in distance from the transmitter or obstacles like buildings. As long as the signal is strong enough to be received, the quality remains consistent.
AM signals can be significantly affected by signal strength variations, leading to fluctuations in volume and clarity.
4. Efficient Use of Power:
FM transmitters can operate more efficiently because they do not need to vary the amplitude of the signal. This allows for more efficient use of power, as the transmitter can operate at a constant power level.
AM transmitters must vary the amplitude of the signal, which can lead to less efficient power usage and higher energy consumption.
5. Reduced Interference from Other Stations:
FM signals are less likely to interfere with each other because they are separated by frequency. This allows for more stations to operate in the same geographic area without causing interference.
AM signals are more prone to interference from other stations, especially at night when AM signals can travel farther due to ionospheric reflection.
6. Stereo Broadcasting:
FM supports stereo broadcasting, which allows for the transmission of two separate audio channels (left and right) to create a more immersive listening experience.
AM typically does not support stereo broadcasting, although there are some AM stereo systems, they are not widely adopted.
7. Less Affected by Multipath Distortion:
FM is less affected by multipath distortion, which occurs when signals reflect off buildings, mountains, or other obstacles and arrive at the receiver at slightly different times. FM receivers can better handle these reflections without significant degradation in quality.
AM is more susceptible to multipath distortion, which can cause fading and distortion in the received signal.
8. Higher Bandwidth:
FM signals typically use a wider bandwidth, which allows for the transmission of more information and higher-quality audio.
AM signals use a narrower bandwidth, which limits the amount of information that can be transmitted and results in lower audio quality.
Summary:
FM is generally preferred over AM for high-fidelity audio broadcasting, such as music and high-quality voice transmission, due to its superior noise resistance, better sound quality, and more efficient use of power. AM, while simpler and capable of longer-range transmission under certain conditions, is more susceptible to noise and interference, making it less suitable for high-quality audio applications.