Amplitude modulation (AM) is also commonly called “dual-band amplitude modulation” (DSB-AM). This term emphasizes that in AM, the upper and lower sidebands of the modulated signal contain the same information as the original baseband signal.
The carrier wave in AM is amplitude modulated to encode the information signal, resulting in a modulated signal that consists of the carrier wave and its two sidebands.
The modulation wave, which is the signal carrying the information to be transmitted, is often called a “baseband signal” or “message signal.” This term emphasizes that the modulation wave usually contains the actual data or information transmitted via the modulation.
In AM, this modulating wave varies the amplitude of the carrier wave according to the instantaneous amplitude of the baseband signal.
The modulation index m in amplitude modulation (AM) is also known as “modulation depth” or “modulation percentage”. It represents the ratio of the maximum amplitude of the modulation signal (baseband signal) to the amplitude of the unmodulated carrier wave. The modulation index m determines the extent to which the amplitude of the carrier wave is varied by the modulation signal.
Higher values of m indicate more significant variations in carrier wave amplitude, resulting in greater changes in signal amplitude and more efficient use of transmitter power.
Amplitude modulation (AM) and frequency modulation (FM) are distinct modulation techniques used in radio communication. They differ fundamentally in how they encode information on a carrier wave. In AM, the amplitude of the carrier wave is modulated to reflect variations in the amplitude of the baseband signal.
In contrast, FM modulates the frequency of the carrier wave, where the frequency deviation corresponds to the amplitude of the baseband signal. This difference means that AM and FM are not the same; They offer different benefits and are used for different types of communications applications depending on factors such as signal clarity, bandwidth efficiency, and noise resilience.
Pulse amplitude modulation (PAM) is also known by the term “pulse modulation”.
PAM is a modulation technique where the amplitude of a series of pulses varies according to variations in the amplitude of the analog signal (modulating wave) transmitted. Each pulse in PAM corresponds to a sample of the modulation wave at a specific instance in time, and the amplitude of the pulse represents the instantaneous amplitude of the modulating signal. PAM is commonly used in digital communications systems, where it forms the basis for more complex modulation schemes like pulse code modulation (PCM) used in digital audio and telecommunications
