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2.1 Modulation And Demodulation
CHAPTER 2
MODULATION TECHNIQUES
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2.1 Modulation and Demodulation
Modulation is a process of changing one or more properties of the high frequency analog carrier signal either its amplitude, frequency or phase in proportion with the values of the low frequency information signal.
Figure 2.1: Modulation Process
The analog or digital information signals combines with the carrier in the modulator to produce a high frequency modulated signal. Modulated signal is the carrier signal that has been changed by information signal. The modulation is performed in a transmitter while the demodulation is performed in a receiver.
Figure 2.2: Demodulation Process
Demodulation is the reverse process of modulation where the information signal is extracted from the modulated signal in the demodulator. The demodulated signal is the original information signal.
Information Signal (Low Frequency) Modulator Modulated Signal (High Frequency)
Carrier Signal (High Frequency)
Modulated Signal (High Frequency) Demodulator Demodulated Signal (Low Frequency)
