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

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.

Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Figure 9-9 Digital signal encoding formats.

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

Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Table 9-1 NRZ Codes

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

Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Table 9-2 RZ Codes

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

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

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

Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Table 9-4 Multilevel Binary Codes

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.

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.

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.

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.

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.

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.

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

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

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

Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Figure 9-12 T1 multiplexing and framing.

Electronic Communications: A Systems Approach Beasley | Hymer | Miller Copyright © 2014 by Pearson Education, Inc. All Rights Reserved Table 9-7 The CSU/DSU Alarms

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

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

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.

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.

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.

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.

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 = 3k * (Log 3163)/Log 2 C = 3k / = 3k * = 34,881 bps