Post on 09-Jul-2020
IQ Modulator/Demodulator
2006-12-06 By 小宗宗
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ModulationModulation is a higher frequency carrier signal carry a lower frequency message signal in a receiver and discard the carrier signal to get the original message signal in the demodulator.
There are three ways for digital information to be carried.Using amplitude shifting (AM)Using frequency shifting (FM)Using phase shifting (PM)
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Three types of modulation
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Polar coordinate systemThese two representations are equivalent and contain the exact same information, just in different forms.
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Using the trigonometry to proof the I/Q equation
I=Amplitude of the “In-Phase Carrier”Q=Amplitude of the “Quadrature-Phase Carrier”
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Block diagram of an IQ modulator
What is the advantages of I/Q modulation?
Hardware circuit is easy to design.
More flexible.
Quadrature Phase Shift Keying (QPSK)
QPSK IQ Diagram
Non-return-to-zero (NRZ)
QPSK Modulator
QPSK Demodulator
Matlab Simulation
Block diagram of Modulator
The scopes of each point
The scopes of each point (continue)
Block diagram of demodulator
The scopes of each point
The scopes of each point (continue)
The scopes of each point (continue)
Fin