Theory behind the application
• The general process of embedding an information varying signal into a
second signal is modulation.
• Extracting the information varying signal is known as demodulation.
Modulation methods rely on the concepts of
1. Amplitude modulation
2. Frequency modulation
3. Phase modulation
• Let x(t) be the information varying speech signal and c(t) be the carrier
signal. Then ,the modulated signal y(t) is given by
y(t)=x(t)c(t)
A speech signal typically has a low frequency range(200hz to 4khz).
Modulation is the key to transmit a voice signal x(t)at different range of
frequencies.
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