Tuesday, October 27, 2015
- Carier Signal
A
carrier is a radio frequency (RF) electromagnetic wave that transmits or carries: the information signal. Within
the modulator, the information signal modulates or alters the carrier signal to
form the modulated carrier signal
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| RF Modulation |
- Sinewave Carrier
A
sinewave may be modulated by varying any of its three characteristics:
1.Amplitudo (A)
2.Frequency (ω)
3.Phase (ϕ)
- Sinewave Carrier Modulation Amplitude Modulation
In an AM signal, the instantaneous
amplitude of the modulated carrier signal changes in direct relation to the
instantaneous amplitude of the information signal.
- Sinewave Carrier Modulation Frequency Modulation
A
larger information signal amplitude result in a proportionally greater
frequency change in the modulated carrier signal.
- Sinewave Carrier Modulation Phase Modulation
In
a ϕ
modulation signal, the phase angle of the modulated carrier signal changes with
respect to its reference in direct relation to the instantaneous amplitude of
the information signal.
A
larger information signal amplitude result in a greater phase shift in the
modulated carrier signal.
- Pros and cons Using AM, FM & PM
•AM : is effective to broadcast radio
signal to large number of people. Because
the receiver design is simple and cheap to manufacture.
•FM : is effective when signal fidelity is
important such as for audio music. Because
the FM technique results in a much higher signal-to-noise ratio at the receiver.
•PM : is
enable greater amounts of digital data to be transmitted by encoding multiple
data bits in each phase change of the carrier. Φ
modulation can send at a higher data rate than AM.
-From Multiple Sources
