TYPES OF MODULATION
Amplitude modulation (AM) is a modulation technique used in
electronic communication, most commonly for transmitting messages
with a radio carrier wave. In amplitude modulation, the amplitude (signal
strength) of the carrier wave is varied in proportion to that of the message
signal, such as an audio signal. In amplitude modulation, the amplitude
or strength of the carrier oscillations is varied. For example, in AM radio
communication, a continuous wave radio-frequency signal (a sinusoidal
carrier wave) has its amplitude modulated by an audio waveform before
transmission. The audio waveform modifies the amplitude of the carrier
wave and determines the envelope of the waveform. In the frequency
domain, amplitude modulation produces a signal with power
concentrated at the carrier frequency and two adjacent sidebands. Each
sideband is equal in bandwidth to that of the modulating signal, and is a
mirror image of the other. Standard AM is thus sometimes called "double-
sideband amplitude modulation" (DSBAM). Single-sideband amplitude
modulation.
A disadvantage of all amplitude modulation techniques, not only standard
AM, is that the receiver amplifies and detects noise and electromagnetic
interference in equal proportion to the signal. AM broadcast is not
favoured for music and high-fidelity broadcasting, but rather for voice
communications and broadcasts (sports, news, talk radio etc.). AM is also
in efficient in power usage; at least two-thirds of the power is
concentrated in the carrier signal.
Frequency modulation (FM) is the encoding of information in a carrier
wave by varying the instantaneous frequency of the wave. The
technology is used in telecommunications, radio broadcasting, signal
processing, and computing. In frequency modulation, such as radio
broadcasting, of an audio signal representing voice or music, the
instantaneous frequency deviation, i.e., the difference between the
frequency of the carrier and its centre frequency, has a functional relation
to the modulating signal amplitude. Frequency modulation is widely used
for FM radio broadcasting.
Amplitude modulation (AM) is a modulation technique used in
electronic communication, most commonly for transmitting messages
with a radio carrier wave. In amplitude modulation, the amplitude (signal
strength) of the carrier wave is varied in proportion to that of the message
signal, such as an audio signal. In amplitude modulation, the amplitude
or strength of the carrier oscillations is varied. For example, in AM radio
communication, a continuous wave radio-frequency signal (a sinusoidal
carrier wave) has its amplitude modulated by an audio waveform before
transmission. The audio waveform modifies the amplitude of the carrier
wave and determines the envelope of the waveform. In the frequency
domain, amplitude modulation produces a signal with power
concentrated at the carrier frequency and two adjacent sidebands. Each
sideband is equal in bandwidth to that of the modulating signal, and is a
mirror image of the other. Standard AM is thus sometimes called "double-
sideband amplitude modulation" (DSBAM). Single-sideband amplitude
modulation.
A disadvantage of all amplitude modulation techniques, not only standard
AM, is that the receiver amplifies and detects noise and electromagnetic
interference in equal proportion to the signal. AM broadcast is not
favoured for music and high-fidelity broadcasting, but rather for voice
communications and broadcasts (sports, news, talk radio etc.). AM is also
in efficient in power usage; at least two-thirds of the power is
concentrated in the carrier signal.
Frequency modulation (FM) is the encoding of information in a carrier
wave by varying the instantaneous frequency of the wave. The
technology is used in telecommunications, radio broadcasting, signal
processing, and computing. In frequency modulation, such as radio
broadcasting, of an audio signal representing voice or music, the
instantaneous frequency deviation, i.e., the difference between the
frequency of the carrier and its centre frequency, has a functional relation
to the modulating signal amplitude. Frequency modulation is widely used
for FM radio broadcasting.
