25-07-2012, 02:29 PM
Modulation
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Modulation is a process that causes a shift in the range of
frequencies in a signal.
• Signals that occupy the same range of frequencies can be
separated
• Modulation helps in noise immunity, attentuation - depends on
the physical medium
Figure 1 shows the different kinds of analog modulation schemes
that are available
Double Side Band - Suppressed Carrier
(DSB-SC) Modulation
• In AM modulation, transmission of carrier consumes lot of
power. Since, only the side bands contain the information
about the message, carrier is suppressed. This results in a
DSB-SC wave.
• A DSB-SC wave s(t) is given by