#### • Class 11 Physics Demo

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Let us first define modulation before diving into the understanding of th definition of amplitude modulation and the disadvantages of amplitude modulation. Modulation is the process in which any one feature of the wave is changed. The changed wave is called the carrier wave. The signal with which the carrier wave’s property is changed is called modulating signal. This signal contains the actual information that has to be conveyed. So we can say that we are transmitting information with hole of another wave. This signal will contain the information. The wave is used because it can be transmitted over a physical channel.

Any property of the carrier wave can be changed or altered by the help of modulating signal. We classify the types of modulation on the basis of which property is altered.

Let us now talk about the definition of amplitude modulation. In this type of modulation the amplitude of the carrier wave is increased. Amplitude or strength is the same. It can lead to the formation of double sidebands which are mirror image of each other.

Disadvantages of amplitude modulation are many and they are stated below -
1. This type of transmission can be affected by natural sources of radiation. It can lead to electromagnetic interference. This may lead to disruption of the original signal or distortion.
2. This type of transmission is also affected by the man made noises or radiations like waves from other antennas or channels.
3. It cannot be used for transmitting music as done by FM.
4. It can only be used for sports talks etc.
5. Now we know that the carrier signal does not have any information that is transmitted and which is the entire reason for modulation. But in Amplitude modulation we have almost two third of the energy or power is in carrier waves. We can reduce this by cutting the carrier wave but then we have to have complex receiver equipment. Having such equipment is again costly. Hence serves no purpose.
6. In this type of modulation, for one transmitter we will have many corresponding receivers which further increase the cost.
7. It cannot be used for transmission of sensitive information like in army etc. where loss or disruption or interpretation during transmission is not an option.
8. All the above can lead to a bad overall and soppier transmission.
9. The bands in which this type of modulation is used is also low that means it is used in low frequency transmission.
10. It is again important to note that whatever we are doing in this type of transmission is the information present in sidebands. That is all the information is present in the sidebands. And all the power is used by the carrier waves.
All the above have affected the use of amplitude modulation a lot and even adversely. It has been limited to very primitive uses and is not use for Hi fi communication or transmissions. It has been suppressed in recent years due to the use of Frequency modulation.