data communication unit 2
TRANSCRIPT
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Digital-To-Digital ConversionLINE CODING: data element signal element
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DATA RATE AND SIGNAL RATE The data rate is measured in bps (bits/sec). The data rate is also called bit rate. The signal rate is measured in baud. The signal rate is also called pulse rate, modulation rate, or baud rate.
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Unipolar Scheme
Polar Scheme
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Return to Zero (RZ)
BIPHASE Manchester and Differential Manchester
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BIPOLAR SCHEMES (MULTILEVEL BINARY)(i)AMI (alternate mark inversion)
(ii)Pseudoternary
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MULTILEVEL SCHEMES2B1Q (Two binary, one Quaternary)Transition Table
Previous level=positive Previous level=negativeNext bits Next level Next level
00 +1 -101 +3 -310 -1 +111 -3 +3
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ANALOG TO DIGITAL CONVERSIONPulse Code Modulation (PCM)
1.Sampling:
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2. Quantization:
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3. Encoding:For example, if a sample has quantization code of 2, then it is encoded as 010, similarly, 5 is encoded as 101, and so on. The bit rate will be
SNRdB = 6.02nb + 1.76 dB
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DIGITAL-TO-ANALOG CONVERSION
An analog signal carries 4 bits per signal element. If 1000 signal elements are sent per second, find the bit rate.
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Amplitude Shift Keying (ASK)
Implementation
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Frequency Shift Keying (FSK)
Implementation
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Phase Shift Keying
Implementation
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Quadrature PSK (QPSK)
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Constellation Diagram
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Quadrature Amplitude Modulation (QAM)
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ANALOG-TO-ANALOG CONVERSION
Amplitude Modulation:
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Frequency Modulation:
Phase Modulation: