Difference Between AM and FM (With Table)

Modulation is a simple process through which a message signal is transmitted from one place to another with the help of a high-frequency signal or carrier signal. It is a process of interposing a low-frequency signal with a high-frequency signal. Amplitude Modulation (AM) and Frequency Modulation (FM) are types of Analog Modulation, Both are used in the transmission of information in the form of electromagnetic waves.

AM vs FM

The main difference between Amplitude Modulation (AM) and Frequency Modulation (FM) is that in Amplitude Modulation, the carrier wave is modified by varying the amplitude of the carrier wave while keeping the frequency constant. Whereas in the case of Frequency Modulation (FM), the carrier wave is modified by varying the frequency of the carrier wave while keeping the amplitude constant.

Amplitude Modulation known by the abbreviation AM is a method of broadcasting radio signals, it is a much older method than Frequency Modulation. In this technique, the information is encoded by varying the amplitude of the signals and keeping the frequency constant.

Frequency Modulation known as FM is a newer method of broadcasting radio signals. In this method, the carrier waves are modulated by corresponding input signals. In this technique, the frequency of the carrier, signals are modulated, and the amplitude is kept constant

Comparison Table Between AM and FM

Parameter Of ComparisonAMFM
Full formThe full form of AM is Amplitude ModulationThe full form of FM is Frequency Modulation
Originated in the yearAM is originated in the mid 1870sFM is introduced in the year 1930s in United States.
Introduced ByAM is introduced by Reginald Fessenden.FM is introduced by Edwin Armstrong.
Difference in ModulationIn Amplitude Modulation (AM) the carrier signals are modulated by keeping the frequency constant and varying the amplitude.In Frequency Modulation(FM) the carrier signals are modulated by keeping the amplitude constant and varying the frequency proportionately.
Range of FrequencyThe frequency range of Amplitude Modulation lies in between 535 kHz to 1705 kHzThe frequency range of Frequency Modulation lies in between 88MHz  to 108 MHz
Distance CoverageAM signals can cover longer distance FM signals can not cover longer distance alone it requires multiple stations for receiving and sending signals
Sound quality of SignalIt produces high level of noise and makes the sound quality  poorIt produces less noise and the sound quality is good
Complexity & Cost of transmitter and receiverThe transmitter and receiver in case of AM are not complex and are economicalThe transmitter and receiver in case of FM are complex and expensive

What is AM?

Amplitude modulation( AM), is a type of Analog Modulation in which the carrier signals are modulated by varying the amplitude and keeping the frequency constant.

It is an older version of transmitting radio signals. It came into existence in the 1870s.The first AM signal is transmitted by an engineer named Reginald Fessenden. The frequency range of Amplitude Modulation lies in between535 kHz to 1705 kHz

It uses lower frequency signals and is cheaper in comparison to frequency modulation The transmitter and receiver used in Amplitude Modulation is not complex which makes it more easy and preferred option of transmission in long distances.

Merits of using Amplitude Modulation (AM)

  1. It is less costly and economical
  2. It uses a simple demodulator for the transmission of data
  3. It can easily cover a larger distance.

Demerits of using Amplitude Modulation(AM).

  1. It consumes more power for transmission
  2. It also needs very high bandwidth in the transmission process
  3. It makes a high level of noise which makes the quality of the signal very poor.

What is FM?

Frequency Modulation(FM) is also a type of analog modulation, in which the information is encoded by modulating the frequency of carrier wave while keeping the amplitude constant.

This technique was introduced by Edwin Armstrong. The frequency range lies between 88MHz  to 108 MHz

It is widely used in radio communication. The receiver and transmitter used in this technique are relatively complex and expensive in comparison to Amplitude Modulation (AM). However, it is most preferred for its good signal quality and less noise.

Merits of using Frequency Modulation (FM)

  1. It makes less noise in transmission of the data, which in turn provides a good quality of signal.
  2. It uses less power consumption for transmitting the information.
  3. Due to its versatility, it is much preferred in mobile radio communication

Demerits of using Frequency Modulation(FM)

  1. The transmitter and receiver are more complex and expensive in the case of frequency modulation
  2. Here, in FM, the carrier signal cannot cover a longer distance, for covering a longer distance requires multiple stations for receiving and sending the signals.

Main Differences Between AM and FM

  1. In Amplitude Modulation, the Amplitude of the carrier waves is modulated and frequency is kept constant whereas in Frequency Modulation, The frequency of carrier waves is modulated and amplitude is kept constant.
  2. AM uses lower bandwidth and it produce low quality of sound while in FM, Higher bandwidth is used which makes the sound quality much better
  3. The transmitter and receiver used in AM are preferable in terms of less complexity and cost while The transmitter and receiver used in FM are more complex and expensive.
  4. FM signals have a narrow approach in terms of distance coverage, they cannot cover long distances as compared to AM signals. It will require multiple stations for covering a larger area
  5. AM signals use more power consumption in comparison to  FM signals in the transmission of data.

Conclusion

Both Amplitude Modulation (AM) and Frequency Modulation (FM) are used in the transmission of signals. They both are widely used in different sectors.

FM is widely used in Mobile communication and music channels while AM is used in audio and speech broadcasting like news. Both are indeed very important techniques of information broadcasting and are required by the information, its quality, and in which range you want to spread your information.

References

  1. https://ieeexplore.ieee.org/abstract/document/1670876/
  2. https://ieeexplore.ieee.org/abstract/document/1670711/