Amplitude modulation (AM) is a widely used technique in communication systems for transmitting information through radio waves. It involves varying the amplitude of a carrier signal in proportion to the instantaneous amplitude of a modulating signal (usually an audio signal).
The main application of amplitude modulation is in broadcasting, particularly in the field of radio broadcasting. Here are some key applications of amplitude modulation:
Radio Broadcasting: AM is commonly used for broadcasting radio signals in the medium-wave (AM) frequency band. AM allows the transmission of audio signals over long distances by modulating the carrier signal with the audio signal. AM radio stations transmit audio content, including music, news, talk shows, and other forms of entertainment.
Two-Way Radio Communication: AM is utilized in two-way radio communication systems, such as citizen band (CB) radios and aviation communication. These systems enable voice communication for various purposes, such as emergency services, transportation, and personal use.
Shortwave Broadcasting: AM is employed in shortwave broadcasting, which allows long-distance communication. Shortwave signals can travel around the Earth by reflecting off the ionosphere, making it useful for international broadcasting.
Radio Navigation: AM signals are used in certain radio navigation systems, such as Non-Directional Beacons (NDBs). NDBs transmit AM signals that provide navigation information to aircraft and ships, assisting in determining their position.
Radio Alarms and Sensors: AM is utilized in wireless alarm systems and sensors. The modulated AM signals can transmit information about alarm conditions, such as intrusions or environmental changes, wirelessly to a central monitoring station.
It's worth noting that while AM has been widely used historically, some applications have transitioned to other modulation techniques, such as frequency modulation (FM) or digital modulation methods like amplitude-shift keying (ASK), phase-shift keying (PSK), and quadrature amplitude modulation (QAM). Nonetheless, AM remains relevant in specific areas of communication and broadcasting.