digital modulation techniques
DESCRIPTION
Digital ModulationTRANSCRIPT
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Digital modulation techniques
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Modulations systems
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Channel capacity
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Reasons for choosing encoding techniques
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What is modulation ?
• Modulation = Adding information to a carrier signal• The sine wave on which the characteristics of the
information signal are modulated is called a carrier signal
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Analog modulation
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Digital modulation and demodulation
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Signal characteristics that can be modified
signal x(t) = A cos(2πft + Φ)
• A – amplitude
• f – frequency
• Φ – phase (initial angle of the sinusoidal function at its origin
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Modulation
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Modulation (1)
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Digital modulation techniques
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ASK• ASK On-off keying (Amplitude Shift Keying) –
frequency is kept constant, amplitude has 2 levels (for bit 1 and for bit 0)
The binary sequence 0010110010
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FSK (Frequency shift keyring)
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PSK (Phase shift keyring)
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