network communications chapter 7 modems, dsl, cable modems and isdn

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Network Communications Chapter 7 Modems, DSL, Cable Modems and ISDN

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  • Network CommunicationsChapter 7Modems, DSL, Cable Modems and ISDN

  • Public Switched Telephone Network (PSTN)Figure 7.1

  • Telephone Carrier Signal(Sine Wave)Figure 7.2

  • Amplitude Shift Keying (ASK)Figure 7.3

    0

    1

    Original Signal

    Amplitude Modulation

  • Frequency Shift Keying (FSK)Figure 7.4

  • 90 Degree Phase ShiftFigure 7.5

  • Phase Shifting the CarrierFigure 7.6 Note: Error in text

  • Constellation DiagramsFigure 7.7 QPSKFigure 7.8 8-PSK

    0 degree

    90 degree

    180 degree

    270 degree

    00

    01

    10

    11

  • 8 QAM Modulation Figure 7.9Figure 7.10

    270 degree shift

    90 degree shift 180 degree shift

    No shift

    000

    010

    100

    110

    001

    011

    101

    111

    000 001

    011

    010

    101 100

    110

    111

  • 56 Kb/sec Modem ConnectionFigure 7.11

    56K Modem

    Server

    PSTN

    56kbps

    Digital

    Analog Signal

    Digital

    33.6Kbps

    56

    Kbps

    Central

    Switch

  • ADSL ModemAsymmetric Digital Subscriber Line Figure 7.12Figure 7.13

    Telephone

    Switch

    ADSL

    Modem

    ADSL

    Modem

    Subscriber Site

    16-640

    Kbps

    Upstream

    1.5-8Mbps Down Stream

  • ADSL Modem ArchitectureFigure 7.14POTs filters do not operate on the DSL signal!

  • Cable TV DistributionFigure 7.15

    Cable TV

    Head end

    =Coaxial Cable

    Amplifier

    End User

    Trunk Coaxial

    Feeder Coaxial cable

    Drop Coaxial cable

  • Hybrid Fiber Coax (HFC)Figure 7.16

    Cable TV

    Head End

    Fiber

    Node

    Fiber

    Node

    Fiber

    Node

    trunk

    Fiber cable

    Coaxial cable

    End Users

  • A Cable Modem ConnectionFigure 7.17

    Head

    END

    CM

    CM

    CM

    CM

    CM

    CM

    PC

    10Base-T NIC

    UTP cable

    Coaxial cable

  • Sharing a Cable/DSL ModemFigure 7.18Should be a Router and a Hub / Switch

    HUB

    / REPEATER

    Cable Modem

    UTP

    10Base-T

  • ISDN Basic Rate2B + D: 144 Kb/secFigure 7.19

  • Using the Basic Rate Interface2 wiresFigure 7.20

  • ISDN Primary Rate23B + D (T1)Figure 7.2164Figure 7.22

    8 bits 1bit 8 bits 1bit 8 bits 1bit 8 bits 1bit

    B1

    D

    B2

    D

    B1

    D

    B2

    D

  • ISDN PRI ApplicationFigure 7.23

    Central Switch

    NT1

    PRI

    NT2

    (PBX)

    LAN

    Phone

    Phone

    PRI