Amplitude modulation (AM) is used for various purposes in communication systems. Here are some of the main reasons why amplitude modulation is employed:
Broadcasting: AM is commonly used for broadcasting audio signals, such as in AM radio stations. In AM broadcasting, the audio signal (voice or music) is superimposed onto a carrier wave by varying the amplitude of the carrier wave in accordance with the instantaneous amplitude of the audio signal. This modulation technique allows the transmission of audio signals over long distances by utilizing the radio frequency spectrum efficiently.
Simple Implementation: AM is relatively simple to implement compared to other modulation techniques like frequency modulation (FM). The circuitry required for AM modulation and demodulation is typically less complex, making it a cost-effective option for many applications.
Compatibility: AM signals can be easily received by a wide range of devices, including simple receivers. This makes it accessible to a larger audience and allows for compatibility with older devices that may not support more advanced modulation techniques.
Long-range Transmission: AM signals are known to have a better range compared to other modulation techniques. They can propagate over long distances, including across geographical obstacles, with relatively simple antenna systems. This makes AM suitable for long-range communication, such as AM radio broadcasting.
Power Efficiency: AM modulation is power-efficient for the transmission of low-frequency signals. The power used for transmitting the carrier wave remains constant, and only the amplitude is varied to carry the information. This can be advantageous in certain scenarios where power consumption is a consideration.
However, it's important to note that AM has some limitations as well. It is susceptible to noise and interference, which can degrade the quality of the transmitted signal. Additionally, AM has a relatively limited bandwidth, which constrains the amount of information that can be transmitted compared to other modulation techniques like frequency modulation (FM) or digital modulation schemes.