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ELECTRONIC COMMUNICATIONS A SYSTEMS APPROACH CHAPTER Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Electronic Communications: A Systems Approach Beasley | Hymer | Miller Telephone Networks Line Codes and TDM 9
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Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Digital Wired Networks Line Codes Format of pulses sent over communications link. Data first be coded or prepared for transmission. Eliminates need for data states to be represented in terms of absolute voltage levels.
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Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Figure 9-9 Digital signal encoding formats.
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Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Digital Wired Networks Line Codes Maintaining synchronization between transmitter and receiver clocks. Enable a form of error detection. NRZ group of codes: encoding binary data. See Table 9-1: NRZ Codes
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Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Table 9-1 NRZ Codes
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Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Digital Wired Networks Line Codes RZ codes: return-to-zero line- coding formats. See Table 9-2: RZ Codes
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Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Table 9-2 RZ Codes
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Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Digital Wired Networks Line Codes Biphase codes Use in optical systems, satellite telemetry links, magnetic recording systems. See Table 9-3: Phase-Encoded and Delay-Modulation (Miller) Codes
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Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Table 9-3 Phase-Encoded and Delay-Modulation (Miller) Codes
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Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Digital Wired Networks Line Codes Multilevel binary codes More than two levels representing the data. See Table 9-4: Multilevel Binary Codes
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Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Table 9-4 Multilevel Binary Codes
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Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Digital Wired Networks Line Codes Transition between logic states results in fast change in rise or fall times of transmitted pulses. Coding scheme chosen determined by available bandwidth and need for transmitter and receiver to maintain synchronization.
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Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved The T-Carrier System and Multiplexing Time-Division Multiplexing (TDM) Each information signal accesses entire channel bandwidth for only small part of available time.
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Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Figure 9-10 An example of generating a TDMA output.
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Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved The T-Carrier System and Multiplexing Time-Division Multiplexing (TDM) Time-division multiple access (TDMA) Transport data from multiple sources over same serial data channel. T-carrier TDM system PCM data from channel 1 transmitted first, then data from channel 2, and so on in sequence before process repeats.
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Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Figure 9-11 An example of recovering TDMA data.
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Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved The T-Carrier System and Multiplexing Time-Division Multiplexing (TDM) T1 line Capacity for 24 individual, 64-kbps, time- division-multiplexed telephone calls. Fractional T1 (FT1) Only portion of T1 bandwidth being used.
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Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Table 9-5 Data Rates for the T and DS Carriers
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Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Table 9-6 E1 and E3 Data-Transmission Rates
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Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved The T-Carrier System and Multiplexing Time-Division Multiplexing (TDM) Point of presence Point where communication carrier brings in service to a facility. Channel service unit/data service unit (CSU/DSU). See Table 9-7: The CSU/DSU Alarms
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Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Figure 9-12 T1 multiplexing and framing.
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Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Table 9-7 The CSU/DSU Alarms
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Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved The T-Carrier System and Multiplexing Time-Division Multiplexing (TDM) Framing Maintain synchronization of receiving equipment. See Table 9-8: The Function of the 24 ESF Framing Bits
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Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Table 9-8 The Function of the 24 ESF Framing Bits
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Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved The T-Carrier System and Multiplexing Time-Division Multiplexing (TDM) Loopback capability Causes transmitted data to be routed back to originating location.
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Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved The T-Carrier System and Multiplexing Time-Division Multiplexing (TDM) T1 line coding AMI and B8ZS. System capacity and bit rate are not unlimited.
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Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Figure 9-15 An example of the AMI data encoding format.
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Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Figure 9-16 Intentional bipolar violations in B8ZS encoding.
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Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved The T-Carrier System and Multiplexing TDM Channel Bandwidth Shannon-Hartley theorem C= BW * Log 2 (1+SNR), C in bits/sec, BW in Hz, SNR as a ratio not dBs, Note: SNR is Signal power/noise power Example: BW is 3000Hz, SNR is 35 dB, Find channel capacity in bps (C) SNR = 10 35/10 = 3162 => C=3k * Log 2 (1+3162) C=3k * Log 2 3163 = 3k * (Log 3163)/Log 2 C = 3k 3.5001/0.30103 = 3k * 11.627 = 34,881 bps
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