Introduction to Telephony Basics

1

Central Office Concepts

High Level OverviewIntroduction to Telephony Basics

Created by:Eddie Phillips

Revision date: 6/2002

Verizon Course # YYJ8166

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C.O. Concepts - Table of Contents

Slide Topic__________

Purpose 7 Purpose of High Level Overview

Introduction 9 Telephone Services10 POTS – Plain Old Telephone Service11 Special Circuits – Generic Types21 Special Circuit Overview23 Sound versus Frequency25 Analog lines, Digital trunks26 Converting an Analog signal to Digital27 Filtering, Sampling & PAM29 PAM – Pulse Amplitude Modulation30 Quantizing Error31 PCM32 Voice to PAM to PCM

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Table of Contents (Continued)Slide Topic_____________

Data Rate Overview & low bit-rate circuits33 Why Digital?34 Effect of Noise36 Digital Signal Rate 0 – DS037 Data Rates - DS0, DS1, DS339 Time Division Multiplexing – TDM43 DS1 - Digital Signal Rate 147 Uni- and Bi-polar signals51 B8ZS - Binary 8-bit Zero Substitution53 DS3 Multiplexer 55 DS-30 format58 Lines versus Trunks59 Signaling63 Robbed-bit Signaling68 Extended Superframe – ESF 70 ISDN BRI 73 ISDN PRI76 Central Office Layout77 Main Distribution Frame79 MDF - Pair protection

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Table of Contents (Continued)Slide Topic_____ ______

89 DSX-1 cross-connect96 D4 channel bank100 Dual Ringing Generators102 Special Circuits108 ISDN channel bank112 Digital Cross-connect System - DCS115 DCS 1/0 - DS1 input/DS0 cross-connect122 DCS Functional types 126 Hi-cap circuit127 DS1 versus T1129 Line Termination Shelf130 T1 Repeater Housing133 Repeater Housing Symbol134 T1 Repeatered Span Line 137 HDSL143 Fractional T1 (DS1)147 DSX-3 Cross-connect153 M13 Asynchronous Multiplexer148 Fiber Systems - Asynchronous159 Fiber Optic Systems – interoffice components

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Table of Contents (Continued)Slide Topic_____________

166 SONET Fiber Optic Systems169 SONET Hierarchy & Rates173 SONET Rings - UPSR174 SONET Rings - BLSR176 Fiber Cable Termination - LGX189 Tracing an FX circuit through an office190 Wave Division Multiplexing193 Dense WDM196 Wideband DCS199 Broadband DCS201 Microwave Radio208 Digital Loop Carrier (DLC’s)218 MDF in DLC’s – Equipment protection

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Table of Contents (Continued)Slide Topic_______________________

220 ADSL231 Timing 242 Power Diagram249 Main Power Board feeding Trans. Dist. Power Board253 Batteries256 Generator257 AC Transfer Switch258 Grounding - protection from lightning, etc

The pictures on this page are of antique operator cordboards.

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Central Office Concepts

Purpose: To provide an high level overview

of the signal formats, circuits andequipment types that are foundin a typical telephone office.

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Central Office ConceptsOverview - Part One

• Telephone Services - POTS Vs. Special Circuits• Analog to Digital Conversion• Data Rates - DS0, DS1, DS3• Main Distribution Frame• DSX-1, DSX-3 Jacks• D4 Channel Bank• ISDN Banks• DCS 1/0 - Digital Access Cross-connect System

9

Telephone Services

POTS

CLASS

PBX

Centrex

Operator

Call Center

ACDAutomatic Call Distribution

ISP IXCCLEC

DS1Hi-caps

Special Circuits

ADSL

Telephone Office

10

POTSPlain Old Telephone Service

Voice Signal

Telephone Office2 wires, 1 pair

Maximum distance from telephone office – 18,000 feet.Under 12,000 feet is preferred.

11

Special CircuitsEverything Else but POTS

Central Office

To distant office

To Internet

To customer’s network

To ISDN line circuit

Digital Circuits

Alarm & control circuits

Analog Phone

Personal Computer

DS1 Hi-cap to Network

ISDN phone

Computer circuits

Utility company circuit

Overview of Generic Types

12

POTS & Special Circuits

Phone line

Phone line

Trunk

TransmissionEquipment

Network

Digital Switch

Telephone Office

POTS

Special CircuitsAnalog Phone

Personal ComputerDS1 Hi-cap to Network

ISDN phone

Computer circuitsUtility company circuit

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Digital Switch – Nortel DMS-100

14

Digital Switch- Automatic

ElectricGTD-5

15


16


17

MainDistribution

Frame- terminates

copper outsideplant cables &

equipment cables

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Copper outside plant cables

19

Copper cable splice closuresin vault

20

Fiber Optic cable& jumper

termination

21

Special Circuits Overview3 Broad Categories

• Voice-grade circuits– Foreign exchange - draws dial tone from a ‘foreign

office’• Analog Data circuits - non-digital

– ex. Circuits for real-time measurements;– pump starting, water levels, door open/close etc.

• Digital Data circuits• digital circuits, ISDN, hi-caps, etc.

22

Introduction Summary

What a telephone office does:

• POTS – normal 7 or 10 digit dialing forcalls we make everyday.

• Special Circuits – unique circuits requestedby the customer to meet a specific customerrequirements.

23

Sound versus Frequency

Sound Waves- unit of measure is

Hertz or cycles per secondHuman ear - 20 -10,000 Hertz (and higher)

Frequency - Electrical representation of sound

Analog Signal - electrical signal analogous to real sound

24

How voice circuits go through the networkPOTS, Special Circuits

Voice or Analog signal

Voice or Analog signal

Digital signal- analog signal

converted to a binary code - 1’s and 0’s.

NetworkTelephone Office

Telephone Office

25

Analog lines, Digital trunks

Line

Line

Line

Analog Signal

1 0 1 1 0 1 0 1

1 0 1 1 0 1 0 1

Digital Trunk

Telephone Office

Telephone Office

Telephone Office

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Converting an Analog Signal to aDigital Signal

‘1’ - presence of a pulse‘0’ - absence of a pulse

Analog Signal Digital Signal

Binary 8-bit word or ‘byte’

Binary digit or ‘bit’ 1 0 1 1 0 1 0 1

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Filtering, Sampling & PAM - PulseAmplitude Modulation

125 microseconds

Low-pass Filter Output

Original Voice Frequency Signal

8000 times per second (Hertz) sampling

20 Hz to 10,000+ Hz

20 Hz - 4000 Hz

Measuring signal levels in real-time

28

Voice signal voltage ‘sampled’ at125 microseconds intervals.

- 8000 times per second

125 microseconds between measurements

T0 T1 T2 T3 T4 T5 T6 T7 T8 T9 Time

Voltage

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PAM - Pulse Amplitude ModulationVoltage level compared to Quantization level

T0 T1 T2 T3 T4 T5 T6 T7 T8 T9 Time

QuantizationLevel

7 - 111

6 - 110

5 - 101

4 - 100

3 - 011

2 - 010

1 - 001

0 - 000

Decimal - Binary

3-bit binary code

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Quantizing Error – small distortionof signalQuantization

Level

T0 T1 T2 Time

7 - 111

6 - 110

5 - 101

4 - 100

3 - 011

2 - 010

1 - 001

0 - 000

Quantizing Error

Decimal - Binary

3-bit binary code

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PCMPulse Code Modulation

10000001 110000010 2

10000011 310000100 410000101 5

10000110 6

11111111 128

00000001 -100000010 -200000011 -300000110 -4

00000101 -5

00000110 -6

01111111 -128

time

Maximumdistortion

Quantization error

PAM pulse

8-bit Binary Code

00000000 0

Each voltage level has a pre-assigned code

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Voice EncodingVoice to PAM to PCM - 8-bit word

DS0 = 64,000 bits per second

Each PAM valueconverted to8-bit word PCM encoder

125 microseconds

1 0 1 1 0 1 0 1 1 0 1 0 1 1 0 1

8-bits 8-bits

8000 samples/sec X 8 bits/sample= 64,000 bits/sec digital stream per voice channel

33

Why Digital?Analog Transmission Noise Problems

Analog Signal

Signal Plus Noise

After Transmission AttenuationPlus Increased Noise

Amplified Signal Plus Noise

34

Effect of NoiseAnalog versus Digital

+ =

+ =

Signal Noise Received Signal

Signal Noise ReceivedSignal

PCM + NoiseEncoded (PCM)

Analog-only signal plus noise:

Digital Signal plus noise:

35

Summary• Analog lines, digital trunks• Voice frequency:

– Filtered– Sampled – PAM – Pulse Amplitude Modulation– Quantized – PCM – Pulse Code Modulation

8-BIT word – 8,000 times per second• PCM – 64,000 bits/second = 1 DS0

36

Digital Signal rate 0 - DS08-bit format - 64 kbs

DS0 = 8000 8-bit words per second = 64,000 bits/second = 64 kbs

1 0 1 1 0 1 0 1

1 2 3 4 5 6 7 8

Fundamental digital signal in telecommunicationsBuilding block of most of all other signals

125 microsecond interval per 8-bit word

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Data Rates & Formats

• DS1 - 24 DS0's = 24 x 64,000 = 1.544 Mbit/sec

• DS3 - 28 DS1's = 28 x 1.544 Mbs + overhead = 44.736 Mbit/sec

- 672 DS0’s = 24 DS0’s x 28 DS1’s

• DS0 - 64,000 bits/sec (64 kbs) channel - digitized voice or data

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Information is on leading edgeof pulse

1 0 1 1 0 1 0 1

1 2 3 4 5 6 7 8

Width of each pulse is ‘squeezed’ to occupy less time so other circuits can be added in the same time frame.

Information is on the ‘leading edge’ of the pulse.

8-bit word represents a 125-microsecond sampling interval

8-bit word can occupy less time than 125 microseconds

1 0 1 1 0 1 0 1

1 2 3 4 5 6 7 8

Same 8-bit word, but occupying less time.

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Time Division Multiplexing - TDM

1

2

3

24

DS0 - 64 kbs

DS1 - 1.544 Mbs

Low-speed side High-speed side

Bi-directional multiplexer.Only one direction is shown.

TDM

The pulse widths of bits in the 24 channels are ‘squeezed’ to put all 24 channels on one high-speed channel.

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Time Division MultiplexingTDM - 24 DS0’s into a DS1

TDM

DS0 12345

21222324

1 0 1 0 1 0 1 0

DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0

1 0 1 0 1 0 1 0DS0

Only one direction shown

124

Framing bit

Channel

TDM - Interleaved together in time.One frame = 24 channels X 8 bits/chan. + 1 framing bit=193 bits/frame Rate = 193 bits/frame X 8000 frames/sec

= 1,544,000 bits/sec = 1.544 Mbs

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Voice to Digital to TDM

TimeDivision

Multiplexer

Analog to

Digital Converter

1

2

3

24

24 channels ‘multiplexed’ together in time.

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A/D-Mux - TDM – Demux-D/A

TimeDivision

Multiplexer Analog

to Digital

Converter

1

2

3

24

TimeDivision

De-multiplexer Digital

to Analog

Converter

1

2

3

24

24 channels ‘multiplexed’ together in time.

Only one direction is shown.

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DS-1 Digital Signal rate 124 channels TDM + Framing bit

1 DS1 frame is:24 DS0 channels (64 kbs) plus one framing bit= 24 channels X 8 bits/channel + 1 framing bit= 193 bits/frame.

Rate per second: 193 bits/frame X 8000 frames/sec

= 1,544,000 bits/sec -OR- 1.544 Mbs.Framing Bit indicates the beginning of the frame.

12324DS0’s

Framing bit

193 bits/frameDS1 Frame

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Bits in a DS1 are Bi-polarEvery other ‘1’ bit is reversed in polarity

0 1 1 0 1 0 1 1 01101011 0 1 1 0 1 0 1 1

DS1 bit stream

DS0 DS0 DS0

Max bit rate = 1.544 Mbs Max frequency = 772 kHz

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One 24-channel frameA DS1 has a signal going in both directions,

a Transmit signal and a Receive signal

1 24

1 8 1 8

Framing Bit

(24x8) +1 = 193 bits/frame

One 8-bit channel One 8-bit channel

125 microseconds

8-bit channel

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One DS1 frame

1 24

24 8-bit words = 192 bits

Framing bit(1 bit only)

1 2 3 4 5 6 7 87-bit word

8-bit word

24 8-bit words +1framing bit = 193 bits

Least Significant Bit

125 microseconds

TX - TransmitRX - Receive

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Uni-polar & Bi-polar SignalsSignals look different, but binary codes are the same

1 0 1 1 0

1 0 1 1 0

Uni-polar signal

Bi-polar signal

48

Line Frequency of Uni-polar andBi-polar signals

1 0 1 1 0

1 0 1 1 0

A

B

‘B’ has half the frequency of ‘A’

6 times crossing reference line


Uni-polar signal

Bi-polar signal

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Bi-polar signals cut the effectivefrequency in half

1 0 1 1 0

1 0 1 1 0

A

B

A



Uni-polar signal

Bi-polar signal

‘Bipolar’ has half the frequency of ‘Uni-polar’

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Bi-polar SignalsDoubles digital signal distance on copper wire

Cutting the frequency in half, doubles the distance the signal can travel

Uni-polar signal

Bi-polar signal

2 times Distance

Distance

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The Zero Problem B8ZS - Binary 8-bit Zero Substitution

0 0 0 0 0 0 0 08 zero’s

Flat line

0 0 0 1 1 0 1 1

Solution:Substitute with B8ZS line encoding

Bi-polar violation (by design)

8 zero’s line code

One 8-bit word with all ‘0’s

Rule: Every 8-bit word MUST have at least one ‘1-bit’

A code is substituted when all zero’s appear.

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Summary• DS0 – one digitized voice channel• TDM – combines 24 voice channels into a DS1

– Mux – multiplexes DS0’s together in time into a DS1– DeMux – de-multiplexes DS0’s from a DS1 into individual

channels.• Binary digits in a digital bit stream are bi-polar• Bi-polar signals have lower frequency & can travel

further on copper wire.• B8ZS – substitutes a special code for eight zero’s.

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DS3 MultiplexerTDM - 28 DS1’s to 1 DS3

12345678910

262728

DS1 - 1.544 Mbs

DS3 - 44.736 MbsDS3

Multiplexer

28 DS1’sLow-speed side

High-speed side

Multiplex : 28 DS1s to 1 DS3

De-multiplex : 1 DS3 to 28 DS1s

The pulse widths of the bits in the 28 DS1’s are ‘squeezed’ to put all 28 channels on one high-speed DS3 channel.

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DS3 Frame Format

5 4 3 2 128 27 26

DS3 rate = 44.736 Mbit/sec

DS1DS1 DS1DS1DS1DS1DS1DS1 Header

24 DS0 channels for each DS1

• 672 DS0 channels = (28 DS1’s X 24 DS0’s/DS1)• Bi-directional - TX and RX

• 28 DS1 channels plus DS3 framing

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DS-30

• Like a DS1, but with 32 channels instead of 24 channels;no framing bit used.

• 30 channels voice, 2 channels control• European standard• Sometimes used by switch vendors inside digital switches

12332DS0’s

193 bits/frame

DS-30 Frame

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ComparisonDS0, DS1, DS3

DS1

24 DS0’s

DS328 DS1’s

DS0

Digital voice

DS-30

32 DS0’s

Bit rate

64 kbs

1.544 Mbs

2.048 Mbs

44.736 Mbs

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Central Office• Switching

– Lines, Trunks• Transmission

– connection between offices– special circuits– most anything else

• Switching & Transmission are blendingtogether

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1 Trunk = one 2-path digital voice circuit = 1 DS0Transmit & Receive on two separate facility paths

Lines versus Trunks

- access from customer to the network

Line

Trunk - connection from office-to-office

1 Line = one 1-path voice circuitTransmit & Receive on 1 cable pair - analog or digital connection

Line

Telephone Office

Telephone Office

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Signaling

Signaling is the process by which two or more telephone offices communicate between each other to setup and take down a telephone call.

LineLine

Telephone Office

Telephone Office

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In-band Signaling from Telephoneoffice to Telephone office

LineLine

Telephone Office

Telephone Office

A B

A informs B of incoming call.B checks line for on-hook or off-hook condition.B informs A of status of line.B applies ringing to the line. When phone answers, voice path is created between A & B. If off-hook, a busy tone is sent from B to A.When a phone is again on-hook, path is dropped.

Trunk

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SignalingCalling-office to Called-office

LineLine

Robbed-bit Signaling is used to transfer signaling information from calling-office to called-office.Ex. when calling-phone goes off hook; sending dialed digits.

Digital Trunk - DS0

Telephone Office

Telephone Office

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SignalingCalled-office back to Calling-office

LineLine

Robbed-bit Signaling is used to transfer signaling information back from called-office to calling-office.Ex. When called-phone answers, or hangs up.

Digital Trunk - DS0

Telephone Office

Telephone Office

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Robbed-Bit Signaling in DS1

1 6 12 18 24

A frameEvery 6th frame is robbed of the least significant bit in all channels

1 24

1 8 1 8

1 24

1 81 8

Dot isrobbed-bit

channel

193 bit frame 193 bit frame

Channels Channels

Bit is used for signaling, not voice.

DS1 – 24 frames shown

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Robbed-bit Signaling56 kbs - Computer to Computer

LineLine

Robbed-bit Signaling limits the maximum digital bit rate to 56 kbs (DS0=64 kbs).

Digital Trunk - DS0

Telephone Office

Telephone Office

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SS7 Signaling - Signaling System 7Out-of-band signaling

HostOfficeSSP

SS7 Signaling uses a separate data paths to send call setup information from the calling office to the called office. STP

HostOfficeSSP

SCP

Voice path - Trunk

database

This Town That Town

Big CityReally Big City

Line Line

SSP - Signal Service Point - local officeSTP - Signal Transfer Point - one per regional areaSCP - Signal Control Point - database for customer info

data paths

SS7 is implemented nationally & regionally and is required for advanced features such as caller id, etc.

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Summary

• Lines – many one-path circuits• Trunks – fewer two-path circuits• Signaling is used for telephone offices to

communicate so a telephone call can be set up andtaken down.

• Robbed-bit signaling is an in-band signal systemthat uses the least significant bit in a DS0 trunk tosend signaling between offices.

• SS7 is an out-of-band signaling system withadvanced features.

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DS1 Superframe

Superframe = 12 frames grouped together

1 6 12

One frame - 193 bits

1 24

1 8 1 8

193 bit frameFraming bitat beginningof frame beforefirst 8-bit word

DS1 Superframe – 12 frames

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DS1 Extended SuperframeESF

1 6 12 18 24

One frame (193 bits)

- Framing bits of 24 frames = virtual 8000 bits/second channel – just like a DS0.‘Framing Channel’ used to send call setup informationwithout ‘Robbing bits’ from the bit stream.

This allows the entire 64 kbs bandwidth in each DS0 voice channel to send voice information.

Also, the Framing Channel sends error checking codes & information about the status of the facility.

Extended Superframe = 24 frames grouped together

Framing bits – 1st bit in each frameDS1 ESF = 24 frames

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ISDN - Integrated SubscriberDigital Network

• all digital connection from telco to phone• higher quality voice circuits• high speed data lines

Digital Line

1 cable pairTelephone Office

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ISDNBRI - Basic Rate Interface

2 digital voice channelsISDN line cardin line bay orchannel bank

NT1Local 2-wire loop

Network Termination 1

2B + D = 160 kbs

Customer PremiseTelephone office and local loop

Demarcation

1 Bearer channel64 kbs

1 Bearer channel64 kbs

Digital 1-path circuit

BRI

Entire 64 kbs channel used for voice.

ISDN phone

ISDN phone

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ISDNBRI - Basic Rate Interface

One 128 kbs channelISDN line cardin line bay orchannel bank

NT1Local 2-wire loop

Network Termination 1

2B + D = 160 kbs

Customer PremiseTelephone office and local loop

demarcation

Digital 1-path circuit

BRI

2 Bearer channels 128 kbs

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ISDN BRIBRI - Basic Rate Interface – all digital circuit

2 B

D

160 kbs channel

Overhead

64 kbs

64 kbs16 kbs

16 kbs

BRI = 2 x 64kb + 16kb + 16kb = 160kb/sec

2B + D - 2 Bearer channels (2 DS0’S) - 64kb each (voice or data) 1 Data channel - 16kb plus 1 overhead channel for signaling - 16 kb

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ISDN PRI - Primary Rate Interface• DS1 format, but channels are - 23B + D = 24 channels• 23 Bearer channels – 23 DS0’s

- 64 kbs each (voice or data)• 1 data channel - 64kbit – 1 DS0

1 24

FramingBit

125 microseconds8-bit, 64 kbs channels

B B B B B B B B B B B B B B B B B B B B B B B B D

PRI = 23B + D

1.544 Mbs DS1 rate

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ISDN BRI LineInternet connection

PRI, a DS1, uses each entire 64 kbs DS0 channel for information.Signaling information is sent via the Data channel & ESF.Allows for clear channel data transfer – ALL 8 bits in each DS0.No Robbed-bit signaling is used.

PRI TrunkingInternet ServiceProvider (ISP)

Telephone Office

Telephone Office

2B + DPRI – DS1PRI – DS1

75

Summary• ISDN BRI – Basic Rate Interface

– 2B+D - 2 ‘Bearer’ channels, 1 Data channel– Full 64,000 bits/sec – no robbed bits– Higher quality, all digital phone lines– Used also for data connections.

• ISDN PRI – 23B+D– DS1 with 23 full 64kbs rate channels– Used by Internet Service providers for higher speed

connections and ISDN connections.

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Central Office Layout

MDF

ISDN

M13 Mux Fiber Optic System

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DSX-1DSX-1DSX-1

LGX

D4 ChannelBank

HDSL

DS1 line termination shelf

DSX-3DSX-3

DS1

DS1

DS1

DS1

DS1

DS1

DS1

HDSL DS1

VF signal

2B + DBRI

DS3

DS3

OSP fiber cable

fiberjumpers

coaxialcable

coaxialcable

OutsidePlant cables

Span powered DS1 (T1)

DCS1/0

77

MainDistributionFrame – C.O.- 2 sided frame

Vertical side - cable protectorsHorizontal side - line blocks

Horizontal side

Verticalside

78

Main DistributionFrame -Vertical side - pair protectionProtectors- termination of cable pairs- may also have blocks

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Main Distribution Frame in atypical central office

• Pair Protection– Protectors

• terminate the outside plant pair• provide lightning protection on the pair

– Blocks• terminate the lines from the equipment• wired out to a cross connect cabinet

Copper pairsin outside plant cable

Protector

Line equip. jumper Equipment cabling

Terminal block LineEquipment

Bay

80

Vertical side – Cosmic frame

81

Main Distribution Frame cable pairprotector (connector)

- 100-pair termination of cable pairs- lightning protection; sends lightning surge to the c.o. ground field

Protector module (solid state)

82

Main Frame Cable pairprotector- jumpers to line circuits of telephone switch.

83

Main Frame Horizontal side

Blocks- termination of line circuits

84

Blocks onMain Distribution Frame

85

Blocks – Cosmic frame

86

‘Tipping’ cablesfrom frame

to vault

87

Vault – Splice Closures - connects ‘tipping’ cable to

outside plant cable

88

Summary• Main Distribution Frame terminates all

voice grade connections in a telephoneoffice.– Outside Plant cables– Line cables– Special circuits

• Pair protection – each cable pair isgrounded if a lightning surge occurs.

89

Central Office Functional Layout

MDF

ISDN


DCS1/0

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LGX

D4 ChannelBank

HDSL


DSX-3DSX-3

DS1

DS1

DS1

DS1

DS1

DS1

DS1

HDSL DS1


VF signal

2B + DBRI

DS3

DS3

OSP fiber cable

fiberjumpers

coaxialcable

coaxialcable

DSX-1DSX-1DSX-1

OutsidePlant cables

90

DSX-1 Cross-connectConnecting DS1 circuits

between equipment

jacks

30-pair high-frequency cabling from equipment

jacks

DSX-1 module DSX-1 module

DS1 DS1Bantam patch cord (dual)

5-wire jumper(flipped over)

LEDMON

INOUT

LEDMON

INOUT

Terminates DS1’sfrom equipment

Light

30-pair high-frequencycabling from equipment

Terminates DS1’sfrom equipment

91

DSX-1 BaysTerminations for DS1’s

Cross-connects to other DS1’s

92

DSX-1 Bays

93

DSX-1 Bays5-wire jumpers

94

DSX-1 jumpers – what NOT to do

95


MDF

ISDN

DSX-1DSX-1


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DSX-1

LGX

D4 ChannelBank

HDSL


DSX-3DSX-3

DS1

DS1

DS1

DS1

DS1

DS1

DS1

HDSL DS1


VF signal

2B + DBRI

DS3

DS3

OSP fiber cable

fiberjumpers

coaxialcable

coaxialcable

OutsidePlant cables

DCS1/0

96

D4 Channel BankA/D, D/A conversion + TDM

• Aggregates many lowspeed circuits into onehigh speed circuit fortransport

• 24 low speed circuits- converted to 64kbit/sec – DS0

• 1 DS1 high speed side- 1.544 Mbit/sec

24 Voice channels

1 DS1 D4

channelbank

1

24

24 VoiceFrequency

circuits24 DS0’s 1 DS1

A/D, D/A TDM

Low-speedside

High-speedside

97

D4 channel bank

Alcatel (Charles Ind.)- dual di-group - two - 24 channels- common cards in the middle of eachdi-group (digital group)

12 channels

12 channels

Common cardsfor one di-group

98

D4 bank to D4 bank

DS1 D4

channelbank

D4channel

bank

24 Voice channels

Office ‘A’ Office ‘B’

1

24

24 Voice channels

1

24

99

Nortel D4- dual di-group- two - 24 channels- common cards on right side of shelf

100

Dual Ringing Generators

101

Summary

• DSX-1 jacks – terminating DS1 cables,providing cross-connections between DS1circuits.

• D4 Bank – Combines 24 incoming voicechannels into 1 DS1 output.24 Low-speed VF – A/D, D/A – TDM –High-speed DS1.

102

Special Circuits

– FX - Foreign exchange historically most popular special circuit used for extending dial tone from another office

Voice Grade:

Foreign Dial tone office– Washington, DC

ChannelBanks

Local office – Austin, TX

DS1 DS1Network

Line

103

Special Circuits

E & M - Ear & Mouth - used for trunk circuits in electromechanical offices.

Voice Grade:

Analogtrunks

DS1

Analogtrunks

ChannelBanks

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Special Circuits

- ETO - Equalized Transmission Onlyused mainly for sending analog data

• on/off condition• real-time measurements, etc.• utility company circuits

Analog Data:

Data centerChannelBanks

DS1

105

Special Circuits

- Data rates 64 kbs or less (1 DS0 or less)• 2.4 kbs, 4.8 kbs, 9.6 kbs, 19.2 kbs, 56 kbs, 64 kbs

Digital Data:

- Fractional T1 - data rate multiples of 64 kbs• 128 - 384 kbs (2-6 DS0’s)

- operates at a DS1 rate, but with only the DS0’s used turned on.

Typically used with Frame Relay circuits.

ChannelBanks

DS1Digital data Digital data

106

Special CircuitsISDN - Integrated Services Digital Network

– digital connection from telco to phone– 3 DS0's per low speed circuit – 3 slots used.

• ISDN card occupies one slot in channel bank, but the 2nd & 3rd slots are unusable for anything else.• 2 ‘Slot-Blocker’ cards are used to prevent other

cards from being placed in the 2nd & 3rd slots.– 8 ISDN channels MAX per D4 bank or

di-group.

1 2 3 4 5 6 7 8 9 10 11 12

DS1

Slots in channel bank

3 DS0’s used

Channel bankChannel bank

ISDNcircuit

ISDNcircuit

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MDF

ISDN


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DSX-1DSX-1DSX-1

LGX

D4 ChannelBank

HDSL


DSX-3DSX-3

DS1

DS1

DS1

DS1

DS1

DS1

DS1

HDSL DS1


VF signal

2B + DBRI

DS3

DS3

OSP fiber cable

fiberjumpers

coaxialcable

coaxialcable

OutsidePlant cables

DCS1/0

108

ISDN Channel Bank

DS1 ISDN

channelbank

Office ‘A’ Office ‘B’

ISDNchannel

bank

• Only 8 physical slots, not 24 channels• 3 DS0’s per physical slot

• Can interface another ISDN bank, D4 or DACS

1 82 3 4 5 6 7 1 82 3 4 5 6 7

109

Adtran BR1/10 ISDN dual-channel banks- two di-groups (digital groups) per shelf.

110

Summary• Special Circuits:

– Foreign Exchange – dial tone from a different c.o.– E & M – Ear & Mouth – analog trunks– ETO – Equalized Transmission Only – analog data.– Digital Data – data rates from 2.4 kbs to 64 kbs.– ISDN in channel bank uses 3 slots.

• ISDN Banks have 8 channels per di-group.

111


MDF

ISDN

DSX-1DSX-1


Dig

ital s

witc

h

DSX-1

LGX

D4 ChannelBank

HDSL


DSX-3DSX-3

DS1

DS1

DS1

DS1

DS1

DS1

DS1

HDSL DS1


VF signal

2B + DBRI

DS3

DS3

OSP fiber cable

fiberjumpers

coaxialcable

coaxialcable

OutsidePlant cables

DCS1/0

112

DCS–Digital Cross-connect System

• Partial elimination of channel banks• Device to access the DS0’s in a DS1 bit stream, while

keeping the circuits all digital• No analog to digital conversion necessary.• Facilitates a cost-effective management of

special circuits in an office.• Higher quality circuits DS1

DS1

DS1

DACS

DS1

DS1

DS1

113

DCSDigital Cross-connect System

DS1

DS1

DS1

DACSDS1

DS1

DS0 cross-connects

DS1

24 DS0’s each DS1

114

Why have a DCS?Before DCS: Back-to-Back D4’s

D4Channel

Bank

D4Channel

Bank

D4Channel

Bank

D4Channel

Bank

D4Channel

Bank

D4Channel

Bank

DS1

DS1

DS1

DS1

DS1

DS1

VF circuits VF circuits

Jumpers

Main Distribution Frame

115

DCS - 1/0DS1 input / DS0 cross-connectBack-to-Back D4 elimination

D4Channel Bank

.

.

.

.

DS1

DS1

DS1

DS1

DACS1/0

DS1

DS1

DS1

DS0 cross connects in 1/0 DACSD4 bank forlocal circuits.

DS0 cross-connects

in matrix

Port cards

Permanently connected ‘virtual’

cross-connectedDS0 circuits.

116

DS0 cross-connects

in matrix

28 DS1’s

Unit Shelves

28 DS1’s

Unit Shelves

Matrix

28 DS1’s 28 DS1’s

28 DS1’s

28 DS1’s

28 DS1’s

Digital Cross-connect SystemUnit shelves & Matrix

DS1 input / DS0 cross-connectInter-shelf bus

117

Dual, on-line matrices and dual data paths for full circuit protection Fully distributed A and B power feeds Dual power supply architecture Single DS1 per port card Distributed processing

Matrix Shelf

Admin Shelf

Filler Panel

Fuse Panel

DS1 Unit Shelf

DS1 Unit Shelf

DS1 Unit Shelf

DS1 Unit Shelf

Fuse Panel

DS1 Unit Shelf

DS1 Unit Shelf

DS1 Unit Shelf

DS1 Unit Shelf

Unit Bay Expansions to 5,376 DS1s

Admin and/or Matrix Bay

DS1 Unit Bay DS1 Unit Bay

Fuse PanelFuse PanelFuse Panel

Disk Drive

DSC - ALCATELDEXCS Bay layout

118

Alcatel DS1 Unit Bay

112 ports per bay

28 ports per unit shelf




1 DS1 per port card

119

AlcatelDEXCS 1/0Bay lineup

Unit bays

Admin bay

Matrix bay

120

Alcatel DEXCS Unit Shelf28 DS1 Ports per shelf

Unit cards ( 28 1-DS1 cards )

Power Supplycard

Controllercards

Power Supplycard

121

Alcatel NarrowbandDEXCS sizes - matrix Size

• CS1S - 84 DS1's - small

• CS1 - 336 DS1's - medium

• CS1L - 1544 DS1's - large

• CS1VL - 5376 DS1's - very large

Matrix Shelf

Admin Shelf

Filler Panel

Fuse Panel

Disk Drive

122

Digital Cross-connect SystemsFunctional types – Generic terms

• Narrowband - 1 / 0– DS1 input, DS0 cross-connect

• Wideband - 3 / 1 – DS3 & DS1 input, DS1 cross-connect

• Broadband - 3 / 3 / fiber– DS3 & fiber optic input, DS3 cross-connect

123

Summary• 1/0 DCS – DS1 input, DS0 cross-connect• DCS accesses all DS0’s in a DS1 bit stream,

while keeping the circuits digital; no A/Dconversion

• reduces the need for back-to-back channelbanks for ‘through’ circuits.

• Saves on equipment quantity and cost,keeps quality of signal high.

• Easier to add, delete, & manage circuits.

124

Central Office ConceptsOverview Part Two

• T1 Span lines, HDSL• M13 Multiplexer• Introduction to Fiber Systems• Fiber Cable Termination – LGX• Broadband DCS• Digital Loop Carrier• ADSL• Timing - BITS Clock• Power - AC/DC, Batteries, Generator• Grounding - protection from lightning, etc.

125


MDF

ISDN

DSX-1DSX-1


DCS

Dig

ital s

witc

h

DSX-1

LGX

D4 ChannelBank

HDSL


DSX-3DSX-3

DS1

DS1

DS1

DS1

DS1

DS1

DS1

HDSL DS1


VF signal

2B + DBRI

DS3

DS3

OSP fiber cable

fiberjumpers

coaxialcable

coaxialcable

OutsidePlant cables

126

Hi-CapHigh Capacity Line – DS1 to Customer

1 2 3 24DS0’s

Framing bit 193 bits/frame

DS1 Frame

Telephone Office DS1

• Various services can be carried on a hi-cap circuit: PBX trunks (voice), Frame Relay, ATM, ISDN PRI, video, etc.• Hi-caps can connect directly to local telco network or pass through to another carrier.

Business or Industry

127

DS1 versus T1

0 Volts

+ 5 Volts

- 5 Volts

0 Volts

+130 Volts

Max bit rate = 1.544 MbsMax frequency = 772 kHz

DC power component added

+135 Volts

+125 Volts

DS1 - low voltage levels, typically 5-12 volts.Limitation of 400 ft in an office.

T1 - has added DC power componentused to power line repeaters.

128


MDF

ISDN

DSX-1DSX-1


DCS1/0

Dig

ital s

witc

h

DSX-1

LGX

D4 ChannelBank

HDSL


DSX-3DSX-3

DS1

DS1

DS1

DS1

DS1

DS1

DS1

HDSL DS1


VF signal

2B + DBRI

DS3

DS3

OSP fiber cable

fiberjumpers

coaxialcable

coaxialcable

OutsidePlant cables

129

Line Termination Shelf(span shelf)

Wired toDSX-1 jacks Wired to block

On MDF to access cable pairs

DSX1

Two 12-pair

Shielded Cables

Two 12-pair

Shielded Cables

12-slot shelf

To cable pairs

C.O. repeater cards

130

T1 Repeater Housing

To next repeater housingFrom previous repeater housing

12 - Position25 - Position50 - Position

Housings

Aerial or Buried Cable

Local Cable or Toll Cable (T-Screen)

Telephone pole

131

Span line repeater housingregeneration of signal

Pulse degenerates into: Repeater makes a new pulse:

Line repeater card

To next repeater housingFrom previous repeater housing

132

New Pulse Generation symbols

One pairin and out

Repeater makes a newpulse in each direction

Side 1

Side 2

133

Repeater HousingSymbol

Side 1

Side 2

134

T1 Repeatered Span LineCentral Office ‘A’

Line Termination ShelfCentral Office ‘B’

Line Termination Shelf

Repeater Housings

C.O. repeater

Line Repeater,

12, 25, 50 slots

Outside plantcopper cable

135

Line termination shelf

Line termination shelf

T1 Repeaters

T1 Span Line - SchematicSpacing Between

Housings- 3000-5000 feet

DS1 in

DS1 out

DS1 out

DS1 in

DC power componentadded to signal to powerrepeater housings - see slide ‘DS1 vs. T1’

T1 signal (DC powered DS1)

C.O.Repeater

Office A Office B

Typically, no new T1 span lines are placed, except in rural areas.

136


MDF

ISDN

DSX-1DSX-1


Dig

ital s

witc

h

DSX-1

LGX

D4 ChannelBank

HDSL


DSX-3DSX-3

DS1

DS1

DS1

DS1

DS1

DS1

DS1

HDSL DS1


VF signal

2B + DBRI

DS3

DS3

OSP fiber cable

fiberjumpers

coaxialcable

coaxialcable

OutsidePlant cables

DCS1/0

137

HDSL

High-bit-rate Digital Subscriber Line

Delivers DS1’s to remotes, DS1’s forcustomer high-caps WITHOUT a repeaterup to 12,000 feet.

Central OfficeHDSL

Remote / Customer Premise

HDSL

No repeater housings

Up to 12,000 feet

138

HDSL

00

01

10

11

• 2B1Q - 2 binary, 1 Quaternary• Two Binary digits per pulse• 4 Pulse levels• cuts line frequency in half from T1 HDSL=384 kHz; T1=772 kHz

Distances up to 12,000without a repeater.

139

HDSL shelf & wiring

12-pair high-frequency cabling to DSX-1 jacks

12-pair high-frequency cabling to main

distribution frame

C N T R L

H T U R

H T U R

H T U R

H T U R

H T U R

H T U R

H T U R

H T U R

H T U R

H T U R

H T U R

H T U R

H T U R

H D S L

140

HDSL shelf

Wired toDSX-1 jacks

Wired to block on MDF to access cable pairs

DSX1

Two 12-pair

Shielded Cables

Two 12-pair

Shielded Cables

13-slot shelfTo

cable pairs

HTU-C cards

HDSL controller card

MDF Block

141

HDSLHTU-C & HTU-R

HTU-C HTU-R2-wire circuit 12 DS0’s

2-wire circuit 12 DS0’s

DS1DS1

Central Office Customer Premise

Up to 12,000 feet

HTU-C - HDSL Terminating Unit - Central OfficeHTU-R - HDSL Terminating Unit - Remote

DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0 DS0




142

HDSL Repeaterdoubles the distance

HTU-C


2-wire circuit 12 DS0’sDS1



HDSL Repeater HTU-R

12,000 feet 12,000 feet

DS1

Central OfficeCustomerPremise

Two HDSL repeaters may be used to go 36,000 feet

143

Fractional T1 (Fractional DS1)• DS1 rate, but with only a portion of the 24 DS0’s carrying

traffic - can be delivered via a T1 span line or HDSL• customer wanting MORE than ONE 64Kbps channel• typically 2-6 DS0's - rate - 128kbps to 384kpbs• Can be provisioned on one pair

Framing bit(1 bit only)

24 8-bit words +1framing bit = 193 bits

124

12345678

6

6 DS0’s shown

144

Fractional T1 over HDSL

D4 bank

HTU-C HTU-R

2-wire circuit, 2-6 DS0’s, 12 max

Central OfficeCustomer Premise

Up to 12,000 feet

Only one pair requiredDS1

4-wirecircuit

Fractional DS1 (6-DS0) 2-wire circuit

MDF

LC

24

Customer’sEquipment





DS0 DS0 DS0 DS0 DS0 DS0

DS0 DS0 DS0 DS0 DS0 DS0

24Fractional T1 with 6 DS0’s carrying traffic

1

1

6 DS0’s in D4 bank

High-speedside

Low-speed side

1 6 12

1612

145

Summary

• Hi-cap – DS1 to customer• T1 span line – transports DS1’s on copper

cable facilities from one office to another;uses T1 repeater housings 3000-5000 feetapart.

• HDSL – transports DS1’s on copper cablefacilities up to 12,000 feet without arepeater housing.

146


MDF

ISDN

DSX-1DSX-1


Dig

ital s

witc

h

DSX-1

LGX

D4 ChannelBank

HDSL


DSX-3DSX-3

DS1

DS1

DS1

DS1

DS1

DS1

DS1

HDSL DS1


VF signal

2B + DBRI

DS3

DS3

OSP fiber cable

fiberjumpers

coaxialcable

coaxialcable

OutsidePlant cables

DCS1/0

147

DSX-3 Cross-Connect- connecting DS3 circuits

between equipment

cross-connect cables(backside of modules)

jacks

coaxial cablingfrom fiber

optic terminal

jacks

DSX-3 module DSX-3 module

coaxial cablingFrom M13 mux

DS3 DS3Patchcords

INOUTI-XO-X

INOUTI-XO-X

MONMON

Light

Cables flipped over

FrontFrontRearRear

148

DSX-3 Bay – front

149

DSX-3 Lineup

150

DSX-3 Bay-Rear View- equipment termination- cross-connect cables

151

Coaxial Terminations

152


MDF

ISDN

DSX-1DSX-1


Dig

ital s

witc

h

DSX-1

LGX

D4 ChannelBank

HDSL


DSX-3DSX-3

DS1

DS1

DS1

DS1

DS1

DS1

DS1

HDSL DS1


VF signal

2B + DBRI

DS3

DS3

OSP fiber cable

fiberjumpers

coaxialcable

coaxialcable

OutsidePlant cables

DCS1/0

153

M13 Asynchronous Multiplexer

• 28 DS1's multiplexup to 1 DS3

• typically use NortelDMT-300 mux orTelco SystemsRC-28D

1

28

DS1

DS3 M13

Multiplexer

to DSX-3 jacks

to DSX-1 jacks

.

.

.

.

.

.

154

Nortel DMT-300 M13 multiplexer4 drawers per shelf

coaxial cablesfor DS3terminations

30-pairHigh-frequencyCabling for28 DS1 terminations

Multiplexer (mux) drawer

empty slot

155

Telco 828 M13 multiplexer

156

NEC RC-28D M13 Multiplexer

157


MDF

ISDN

DSX-1DSX-1


Dig

ital s

witc

h

DSX-1

LGX

D4 ChannelBank

HDSL


DSX-3DSX-3

DS1

DS1

DS1

DS1

DS1

DS1

DS1

HDSL DS1


VF signal

2B + DBRI

DS3

DS3

OSP fiber cable

fiberjumpers

coaxialcable

coaxialcable

OutsidePlant cables

DCS1/0

158

Fiber System - AsyncFundamental structure

DS3

DS3

Fiber Optic Terminal

working

protection

TxRx

TxRx

.

.

.

.

DSX3

159

Fiber optic system -interoffice components


FOT

DS3’s

Office A


FOT

DS3’s

Office B

LGX

LGX

Outside plantfiber cable

Fiber opticsplice closure

Inside plant‘mic’ cable

DSX3

DSX3

Fiber terminationpanel

Point-to-Point configuration

160

Basic Fiber Optic TerminalSimplified block diagram

DS3 #1

DS3 #2

DS3 #3

working

protection

Low-speed side, orEquipment side

High-speed side, orFacility side

To DSX-3 panels To outside plant fiber facilities

DE

MUX

XCVR

MUX

XCVR

45 Mb/s

135 Mb/s

Light – 1300 nmwavelengthTx or In

Rx or Out

DS3

DS3

DS3

3-DS3 Fiber Optic Terminal

161

FD-565 Fiber Optic Terminal

Controllercard

Transmit card Receive card

Working sideOptics cards

(Tx, Rx,Mux, Demux)

Protection sideOptics cards

Power supplies

DS3 interface cards

Fiber jumper slack storage

Coaxial termination

162

Multiplexing Hierarchy & wiring


FOT

DS3M13mux

DS1 #1

DS1 #28

D4Channel

bank

DS0 channel 1

DS0 channel 24

Fibers to next office

Coaxialcable

30-pair24-gaugeshielded

cable

25-pair24-gauge

voice frequency

cable

64 Kbs1.544 Mbs 45.736 Mbs

163

Test EquipmentDS1, DS3, SONET T-Berd

Acterna Products - formerly TTC

164

Mux, DSX-3, & F.O.T.connections

DS3

.

.

.DS3

FiberOptic

Terminal

working

protection

TxRx

TxRx

DS3

DSX-3PANEL

DSX-3PANEL

M13MUX

To fiber termination panel

DS1

coaxialcable coaxial

cable

High-frequency

cabling

coaxial cross-connect

cords

165

Summary• DSX-3 jacks - terminating DS3 cables,

providing cross-connections between DS3circuits. Connects to M13 muxes & FOT’s.

• M13 Multiplexer – TDM device combining28 DS1’s into one DS3.

• Fiber Optic Terminal – TDM devicecombining lower speed DS3 (and DS1)circuits together into a high speed circuit.This high speed circuit is converted into lightpulses and connected to a fiber cable.

166

SONETSynchronous Optical NETwork

• SONET is a standard for synchronous data transmissionon fiber optic equipment.

• STS-1 Synchronous Transport Signal rate 1.- fundamental bit rate within SONET hierarchy.

• SONET rate = 51.840 Mbs. When transmitted via light,called Optical Carrier rate 1, or OC-1.

• STS-1 typically is a DS3 signal within a SONET frame.

5 4 3 2 128 27 26

DS1 DS1SONET Frame

DS3

HeaderDS1DS1DS1DS1DS1DS1DS1DS1

167

SONET FrameSynchronous Transport Signal Rate - 1

Optical Carrier - Rate 1

Frame Rate=9 Rows X 90 Columns X 8 bits/sec X 8000 frames/sec = 51.84 Mbs Payload = 50.112 Mbs, Transport Overhead = 1.728 Mbs

87 Columns

90 Columns

9 Rows

Payload

Transport Overhead

8-bit word

8-bit word

STS-1 – electrical, OC-1 - optical

168

SONETFiber Optic

System

SONETAdvantages:• Mix and match fiber vendors on same span.• Since the SONET bit streams are byte-

interleaved and timed from a common,stable clock source, the individual lower-rate bit streams can be accessed without de-multiplexing the entire bit stream.

DS3

.

.

.

SONETFiber Optic

SystemDS3

.

.

.

.

Vendor “A” Vendor “B”

.

.

.

.

.

.

.

.

.

.

.

.

169

SONET Hierarchy & Rates# DS3's SONET OPTICAL Rate Capacity - DS1's

1 STS-1 OC-1 51.84 Mbs 28 DS1's3 STS-3 OC-3 155 Mbs 84 DS1's12 STS-12 OC-12 622 Mbs 336 DS1's48 STS-48 OC-48 2488 Mbs - 2.4 Gbs 1344 DS1's

192 STS-192 OC-192 9953 Mbs - 9.9 Gbs 5376 DS1's

SONETFiber Optic

SystemDS3

.

.

.

.

.

.

.

170

Lucent DDM-2000OC-3 shelfTransceiver cards

Processorcards

DS1 Interfacecards – Group A28 DS1’s

Group B - emptyGroup C - empty

Drop down door

Timing Cards

171

SONET Fiber Optic SystemSynchronous Optical NETwork – OC12

Fan shelf

Transceiver cards

OperationalController

OPCTiming

cards

Processorcard

DS3 or DS1Interface cards

172

Fujitsu FLM-150 Fiber Shelf

173

12 STS-1’s maximum available around the ring.

SONET RingsUPSR - Uni-directional Path Switched Ring

B

12 STS-1’s

OC-12 UPSR RingNumber of available STS-1’s = rated capacity of system (N)

DS3’s DS3’s

DS3’s

Example:A-B - Ch.1 workingB-C-A - Ch.1 protection

X – where DS3 interfaces the ring.

CONTROL

POWER

POWER

OC -

12XCVR

OC -

12XCVR

PROT .

MAPPER

SW I TCHER

MAPPER 14 DS-1'S

MAPPER 14 DS-1'S

MAPPER 14 DS-1'S

MAPPER 14 DS-1'S

MAPPER 14 DS-1'S

MAPPER 14 DS-1'S

T I

M I N GBC

ONTROL

POWER

POWER

OC -

12XCVR

OC -

12XCVR

PROT .

MAPPER

SW I TCHER

MAPPER 14 DS-1'S

MAPPER 14 DS-1'S

MAPPER 14 DS-1'S

MAPPER 14 DS-1'S

MAPPER 14 DS-1'S

MAPPER 14 DS-1'S

T I

M I N GA

CONTROL

POWER

POWER

OC -

12XCVR

OC -

12XCVR

PROT .

MAPPER

SW I TCHER

MAPPER 14 DS-1'S

MAPPER 14 DS-1'S

MAPPER 14 DS-1'S

MAPPER 14 DS-1'S

MAPPER 14 DS-1'S

MAPPER 14 DS-1'S

T I

M I N GC

174

SONET RingsBLSR –Bi-directional Line Switched Ring

Number of available STS-1’s = N/2 * number of nodes

Each segment is has ½ working STS-1’s and ½ protection STS-1’s

A B

C

½ STS-1’s working &½ STS-1’s protection

½ STS-1’s working,½ STS-1’s protection

½ STS-1’s working,½ STS-1’s protection

CONTROL

POWER

POWER

OC -

12XCVR

OC -

12XCVR

PROT .

MAPPER

SW I TCHER

MAPPER 14 DS-1'S

MAPPER 14 DS-1'S

MAPPER 14 DS-1'S

MAPPER 14 DS-1'S

MAPPER 14 DS-1'S

MAPPER 14 DS-1'S

T I

M I N GBC

ONTROL

POWER

POWER

OC -

12XCVR

OC -

12XCVR

PROT .

MAPPER

SW I TCHER

MAPPER 14 DS-1'S

MAPPER 14 DS-1'S

MAPPER 14 DS-1'S

MAPPER 14 DS-1'S

MAPPER 14 DS-1'S

MAPPER 14 DS-1'S

T I

M I N GA

CONTROL

POWER

POWER

OC -

12XCVR

OC -

12XCVR

PROT .

MAPPER

SW I TCHER

MAPPER 14 DS-1'S

MAPPER 14 DS-1'S

MAPPER 14 DS-1'S

MAPPER 14 DS-1'S

MAPPER 14 DS-1'S

MAPPER 14 DS-1'S

T I

M I N GC

DS3’s DS3’s

DS3’s

6 STS-1’s available in each segment.

OC-12 BLSR Ring

175

Summary

• SONET – standard format for fiber opticequipment.

• Accesses bits in the bit stream withoutde-multiplexing the entire bit stream.

• Allows concatenation of signals togetherfor higher speeds.

• Equipment must be synchronized or timedtogether.

176

Fiber Cable TerminationOSP cable - closure - fiber panel

Outside Plant fiber cable

Inside Plant fiber cable(mic cable)

Fiber closure fiber

connector panel

177

LGXLight Guide Cross-Connect

6-pack

Fiber connectors

Fiber optic connectorBulkhead connector

- mates to fiber optic connector

Pigtail (or jumper)

178

Fiber optic connectors

Fiber optic connector

Bulkhead connector in termination shelf

Mated together in fiber termination shelf

Fiber opticjumper

Fiber opticpigtail

equipment sidefacility side

179

Fiber Optical connectors

ST SC FC BiconicMost commonlyused in telephony

Used in videoapplications

Older type,not beingplaced innew systems

180

Fiber Termination Bays- Lucent

LGX – Light Guide Cross-connect

also called,

OSX- Optical Signal Cross-connect

Facility-side bay &| equipment-side bay

181

Fiber Termination Bay- ADC

Fiber termination panel – jumpers slide out to side

182

Fiber termination shelves

Fiber jumpers

Fiber pigtail (72 in bundle)

Fiber terminationshelf

Connectors (72 per shelf)

Designationstrip

183

OCEF Optical Cable

Entrance Facility

MIC cable from LGX bay

184

Fiber Jumper Inter-connect

FiberOptic

Terminal

Fiber Jumper- connects to front of LGX panel

MIC cable- terminateson back ofLGX panel

Fiber closure LGX panel

Outside Plant Fiber

185

Fiber Jumper ConnectionsInter-connect

FiberOptic

Terminal

Fiber closureLGX panel– top view

EquipmentJumpers (4)

MIC cable12-, 24-, 72-fiber, etc.

Fiber opticconnectors

186

Fiber Jumper cross-connect

FiberOptic

Terminal

Fiber X-CJumper

- terminateson front

mic cable- terminateson back ofLGX panel

Fiber closure

LGX panelfacility side

Fiber equipmentJumper

- terminateson rear

LGX panelequipment side

187

Fiber Jumper ConnectionsCross-connect

FiberOptic

Terminal

Fiber closure

LGX panelfacility-side

LGX panelequipment-side

Cross-connect Jumpers (4)

EquipmentJumpers (4)

MIC cable12-, 24-, 72-fiber, etc.

ST connectors

188

Summary• LGX – fiber cable & jumper termination;

allows for fiber cable management.• MIC cable is fire retardant• ST & SC connectors are the most

commonly used in telephony.• Inter-connect & cross-connect are both

used.

189

Tracing an FX circuit through an officeSummary of circuits, signals & equipment

DS1 D4

channelbank

DSX3

DSX3

DS3 M13

MultiplexerDS1

FX circuit

MDF

DSX-1

work prot


DS3

DSX-1

DSX-1

DS1 DS1

DACS

matrixDS0

DSX-1

LGX

LGX

Outside Plantfiber cable

Fiber jumpers

Over network to ‘foreign exchange’

for dial tone

190

Wave Division MultiplexingWDM

Fiber Optic Terminal #2Rx

Fiber Optic Terminal #1Rx

Fiber Optic

Terminal #2

Tx

Fiber Optic Terminal #1

Tx WDMDevice

WDMDevice

Office A Office B

WDM is used to place multiple wavelengths of light on a single fiber.

+

191

Wave Division MultiplexingWavelengths of Light

Fiber optic lasers traditionally operated at 1310 nm, 1550 nm.Dense Wave Division Multiplexing uses finer increments

of wavelengths – 0.1 nanometers.DWDM uses wavelengths such as 1557.1, 1557.2, 1557.3,1557.4, and higher.

Wave length(s)

Nanometers – nm

Lambda - λ

192

Basic Wave Division Multiplexing

Fiber Optic

Terminal #2

Tx

Rx

Fiber Optic

Terminal #1

Tx

Rx

Fiber Optic

Terminal #2

Tx

Rx

Fiber Optic

Terminal #1

Tx

Rx

WDMDevice

WDMDevice

WDM - passive devices,no power required

Fiber optic cable Between telephone

offices

1310 nm 1310 nm

1550 nm1550 nm

Not shown are the fiber termination panels, etc.

Office A Office B

Requires ONLY four fibers, NOT eight fibers.

Both 1310 nm and 1550 nm light signals are on same fiber in one direction.

Only the Working side is displayed.

λ−1 λ−1

λ−2 λ−2

193

DWDM – Four wave length systemRequires only four fibers, not sixteen fibers.

Only the Working side is displayed.

F.O.T.#1 1557.1 Tx

F.O.T.#2 1557.2 Tx

F.O.T.#3 1557.3 Tx

F.O.T.#4 1557.4 Tx

F.O.T.#1 1557.1 Rx

F.O.T.#2 1557.2 Rx

F.O.T.#3 1557.3 Rx

F.O.T.#4 1557.4 Rx F.O.T.#4 1557.4Tx

F.O.T.#3 1557.3Tx

F.O.T.#2 1557.2Tx

F.O.T.#1 1557.1Tx

F.O.T.#4 1557.4Rx

F.O.T.#3 1557.3Rx

F.O.T.#2 1557.2Rx

F.O.T.#1 1557.1Rx

4-inputWDMDevice

4-inputWDMDevice

Transmitter and receivers must be matched properly.

Office A Office B

194

DWDM – 8 wavelength system

1557.1

1557.2

1557.3

1557.4

1557.5

1557.6

1557.7

1557.8

1557.1

1557.2

1557.3

1557.4

1557.5

1557.6

1557.7

1557.8

8-input WDM device

F.O.T.Transmitters

8-input WDM device

F.O.T.Receivers

Only one direction of the working sides shown.Requires only four fibers, not thirty-two fibers.

Office A Office B

195

Summary

• Wave Division Multiplexing is used to addanother fiber optic system to the same set offibers, but with optic cards with differentwavelengths.

• DWDM adds many fiber systems to thesame set of fibers, with optic cards only0.1 nm apart in wavelength.

196

Wideband DCSDS3, SONET fiber input, DS1 cross-connect

DS3

DS3

DS3

DS3

DCS3/1

DS3

DS3

DS1 cross connects in 3/1 DCS

DS1 cross-connects

in matrix

Port cards

SONET Fiber optic interface

OC-1, OC-3, OC-12

Verizon approvedTellabs Titan 5500

-‘Grooming’ DS1 circuits from one port to another.- Reduces back-to-back equipment.

197

Tellabs Titan 5500SONET 3/1 DCS

198

Titan 5500 unit shelfDS3 input

199

SONET Fiber optic interface

OC-1, OC-3, OC-12

SONET Broadband DCSDS3, SONET fiber input, DS3 cross-connect

DS3

DCS3/3

DS3

DS3

DS3 cross connects in 3/3 DCS

DS3 cross-connects

in matrix

Port cards

‘Grooming’ DS3 circuitsfrom one port to another.

200

Summary• Wideband DACS – DS3/fiber input, DS1 cross-

connect; management of DS1 circuits.• Reduces the need for M13 multiplexers,

DSX-1 jack panels, etc.• Broadband DACS – DS3/fiber input,

DS3 cross-connect; management of DS3circuits.• Reduces the need for fiber optic terminals;

allows direct interface of fiber optics.• Reduces the need for DSX-3 jack panels.

201

Microwave RadioPoint-to-Point Radio Transmission

202

Microwave RadioPoint-to-Point - DS1 & DS3 circuits

Telephone Office

Telephone Office

2 – 11 GigaHertz Microwave carrier

frequencies

Waveguide

Parabolic Dish Antenna

Tower structure

203

Microwave Radio Waveguide

DS3

DS3

MicrowaveRadio

Terminal

DSX-3Panel

coaxialcable

Waveguide

Parabolic Dish Antenna

3-DS3 maximum per radio Tower structure

204

Microwave Radio Equipment

Radio/Antenna Interface - Rigid Waveguide

Telephone OfficeWave guide

Ports

Tower structureMW RadioEquipment

DS1 or DS3Inputs

205

Microwave RadioFrequencies & Distances

• 2 GHz – now used for PCS.Existing systems - grandfathered

• 6 GHz – 11 to 30 miles• 11 GHz – 3 to 15 miles• 18 GHz – 0 to 5 miles• 38 GHz – across the street Typically, transmit power is only

one Watt.Microwave dishes are from 2 – 15 feet in diameter. The larger the dish, the higher the gain, hence greater distanceis achieved.

206

Microwave Radio

Telephone Office Telephone

Office

Passive Reflector

Reflectors are used to bounce microwave beam over or

around an obstruction.

207

Summary

• Microwave Radio – used to transport telephony signals in lieu of fiber cable; over mountains, bodies of water, etc.

• Both DS1 and DS3 circuits are transported

208

Digital Loop CarrierExisting copper plant

600-pair ‘Feeder’ cable

450 homes

100-pair feeder cable


75 homesDistribution cables

Distribution cablesTelephone

Office

209

Digital Loop CarrierDLC added in growing subdivision


450 homes



75 homes

300 new homes

DLC

Distribution cables


Office

210

Digital Loop CarrierDLC distribution cable

& span cable added


450 homes



75 homes

300 new homes

DLCExisting

distribution cable

New T1 ( or HDSL) span cable

New DLCdistribution cable

Distribution cables


Office

211

Digital Loop CarrierDLC is cutover; old feeder cable is

free to be reused


450 homes



75 homes

300 new homes

DLC

New T1 ( or HDSL) span cable

New DLCdistribution cable

Existing 100-pair feeder cablecan be reused for other customers

Distribution cables

Distribution cables

New distribution cablesfor another subdivision

Telephone Office

212

NGDLCNext Generation Digital Loop

Carrier

DLC cabinetCross-connect

cabinet

Concrete pad

• POTS• Special Circuits - ISDN, FX, etc.• Hi-caps• ADSL

Fiber or copper DS1’s to central office

To provide telephone services to areas where it would be economically unfeasible to place copper cable.

AFC AccessMax (formerly UMC-1000A), Alcatel Litespan,Zhone (formerly Nortel) AccessNode,Lucent SLC-96, SLC-5, SLC-2000Marconi DISC*S (Reltec), and others.

213

Digital Loop Carrier cabinet site672 lines maximum

Outside plant cable

Cross connect cabinet

Digital LoopCarrier cabinet

AC Powercabinet

Generator

214

Walk-in Cabinet672 to 2688+ lines

215

Walk-inCabinet

Digital Loop Carrier equipment (lines) directly cabled to protectors. ProtectorsCabled to external cross-connect cabinet – no blocks, no jumpers required in DLC cabinet.

DLC bays Protectors

216

DLCDigital Loop Carrier

Universal arrangement

Line bayMDF

Central Office DLC

Fiber optics or copper DS1’s

672 lines

240 lines

672 linesDLC cabinet

COT - Central Office Terminal

Cross-connectcabinetJumpers

Central office / remote

217

DLCDigital Loop Carrier

Direct interface into switch

DS1 port bay Central Office DLC

Fiber opticsno lines


Cross-connectcabinet

4-6 DS1 connections

Host central office

Copper span linesLine termination shelf

4-6 DS1 connections

DS1interfaces


218

Main Distribution Frame inDLC’s & walk-in cabinets

• Equipment Protection– Protectors

• terminate the lines from the equipment• provide lightning protection on the equipment

– Blocks– terminate the outside plant pair– also used in walk-in cabinets

Cable pair

Protector

Line equip. jumper Equipment cabling

Terminal blockDLCline

equipment

219

Digital Loop Carrier DLC is telephone line

equipment placed inan area where it ismore cost effectivethan placing copperfacilities to the area.

Inter-cabinetcabling

Fiber cableto central office

Cross-Connect cabinet

DLC

protectors

Fibertermination

panel

terminals

jumpers

800-pairEquipment

Side

1600-pairField side

Ground rodsfor ground field

OutsidePlant

distributioncable

220

ADSLAsymmetrical Digital Subscriber

Line

ADSL

Telephone Office

One cable pair

Basic phone circuitAnd

Digital Subscriber Line for High Speed Internet ServiceOn

221

Asymmetrical DigitalSubscriber Line

ADSL

Frequency

4kHz 140 KHz 1.1 MHz

ADSLUpstreambandwidth

ADSLDownstreambandwidth

POTS

Signal level

20 kHz

High speed internet withphone both working at same time.

Signal versus Frequency

Cable Pair Spectrum

222

Basic phone circuit – before ADSL

LC

LineBlock Protector

Main DistributionFrame

Cable PairLine cabling

LC-line card

Jumper

RegularNID

Telephone OfficePOTSLine Bay

223

Basic phone circuit - with ADSL

SplitterNID

LineBlock

POTSLine Bay Protector



ADSLSplitter Block

ATU-R

Jumpers

DS1 to Frame Relay

switch Ethernet connection

Fujitsu SpeedportADSL

ATU|

C

Telephone Office

LC

xLC=xDSL line card

224

Fujitsu ADSL shelf

Jumper to line circuit, andjumper to cable pair

48 circuits per shelf.16 circuits per splitter block.3 splitter blocks required per shelf.

MDF-mountedsplitter block -passive electronics

Newer installations use rack-mounted splitter

225

ADSL Service Offerings• Bronze CIR=10 kbs

256 kbs downstream / 64 kbs upstream• Silver CIR= 32 kbs

384 kbs downstream / 384 kbs upstream• Gold CIR = 64 kbs

768 kbs downstream / 768 kbs upstream• Platinum CIR = 192 kbs

1.5 Mbs downstream / 768 kbs upstream• Platinum Plus - Multi-User CIR=384 kbs

1.5 Mbs downstream / 768 kbs upstreamCIR = Committed Information Rate

226

frequency

4kHz 140 KHz 1.1 MHz

Upstream Downstream

POTS

Signal level

20 kHz

‘Weak’ frequency in cablepair

ADSL “carriers” or “channels227 maximum carriers

3 kHz spacingbetween carriers

‘Carriers’ used by ADSLto send high-speed digital bit stream

0 kHz

QAM – Quadrature Amplitude Modulation.2-8 bits per carrier.

Bit rate64 Kbs-768 Kbs

Bit rate256 Kbs-1.5 Mbs

227

ADSL Components atCustomer Premise

RJ48 ADSL Data

RJ11 Voice

6 Line Protector

Network Interface Card

Power Supply

Homerun RJ48 if Customer has second line.

CAT 5 Patch Cable betweenRJ48 and Modem

CAT 5 Patch Cable betweenModem and NIC card in PC

RADSL Modem

Test Boardin C.O.

228

G.LiteUniversal ADSL

Universal ADSL or G.Lite• Lower bit-rate & lower frequency ADSL service

– 1.5 Mbs downstream / 384 kbs upstream

• Splitter-less NID• Works through special

line card in existingline bay.

G.LiteRegularNID

Cable pair

4kHz140 KHz

1.1 MHz

POTS

20 kHz0 kHz

Upstream Downstream

550 KHz

Microfilter

229

G.Lite

G.LiteUniversal ADSL

xLC

RegularNID

LineBlock Protector



xLC=xDSL line card

2-wirejumper

D-BIC- Splitter-less, lower bit-rate ADSL- 1.5 Mbs downstream- 384 kbs upstream- Standard protocol - works with any vendor’s ADSL equipment- Small modification to line bay

DS1 to Frame Relay

switch

Modificationto Line bay;

D-BICData-Bus

Interface Card

POTSLine Bay

Microfilter

1-pair

230

Summary

• ADSL – POTS & high speed data oversame cable pair.

• Keeps Internet traffic off of the PublicSwitched Telephone Network (PSTN).

• G.Lite – lower speed & splitter-less versionof ADSL.

231

TIMING - What is it?• Everybody is marching to the same 'beat'

• BITS - Building Integrated Timing Supply– Stable timing source for digital networks

• allows equipment to synchronize or'sync up’ to one reliable timing source sodigital circuits are timed together.

232

TIMING - Why is it?• Required for prevention of Binary Digit Slips• a slip is loss of a block of bits due to

frequency shift, phase shift, etc. betweennetworks.

• causes outages, loss of data, audible clickingon line, facsimile distortions

Original Signal

Bit Slip

233

• Purely analog circuits DO NOT requiretiming.

Timing required for:• D4 channel banks – only for digital circuits• SONET fiber systems• DACS• Digital switch

TIMING - For what equipment?

234

TIMING - How?

• BITS Clock Building Integrated Timing Supply Clock

– accurate & stable clock oscillator– obtains timing from the GPS - Global

Positioning System• GPS distributes a timing reference to

non-GPS sites

235

GPS & BITS Clock

GPS receiveron roof

Coaxial or fiber cable fromroof to timing shelf

power cableto roof mountedreceiver

gathers timing referencesfrom multiple satellites

Stratum 2Clock

GPS satellites

236

GPSAntenna

237

3 clock levels of timing - Stratum Levels

Stratum 2 Stratum 2

GPS

Stratum 3 Stratum 3 Stratum 3

TelephoneOffice

TelephoneOffice

Telephone Office

Telephone Office

Telephone Office

Stratum 1 Stratum 1

GPS

238

TIMING - Stratum levels• Stratum 1 Clock - directly from GPS receiver

– typically put at host offices with Stratum 2– stability – infinite – continuously connected to GPS

• Stratum 2 Clock - stability - 28 days w/out externalinput

• Stratum 3 Clock - stability - 5 days w/out externalinput– typically put at main wire centers other than hosts

• Stratum 4 Clock - stability - less than 24 hours– typically for clocks put on fiber optic cards

239

BITS Clock/Timing Distribution Shelf& GPS Antenna control shelf

240

BITS

“TOTA” output.DS1 outputs

to digital switch, 1/0 DACS, 3/1 DACS,

Broadband DACS,SONET fiber optic

terminals, etc.

Stratum 2Clock

Timing Outputs

“TOCA” outputor ‘composite clock’.

DS0 outputsto channel banks,

ISDN banks, DLC’s.

Coaxial cable or fiber cablefrom roof to timing shelf

GPS Antenna

TOCA Output

TOTAOutput

Power cable toroof mountedreceiver

241

Summary

• Timing – keeping all digital circuits andequipment synchronized together to prevent lossof information.

• GPS – Global Positioning System – an accuratetiming source sent from satellites to a roofmounted receiver.\

• BITS – Building Integrated Timing Supply –supplies accurate timing signals for all equipmentin a telephone office.

242

Power

RectifiersAC to DC Batteries

Power Board

- -- +

+shunt

-48V -48VTo

C.O.equipment

+

Common bus for (+) & ( -)

-48VAC

AC

DC DC

c.o. ground bus

Fuses

meters

Output power:large office - 600-10,000+ Amps @ -48 VDCsmall office - 100-600 Amps @ -48 VDC

Input power:- 120/240 Volts-AC - 208 or 440 Volts-AC 3-phase

243

Main Power Board

4 main fuses (600 Amp) - for feeding secondary power boards

Distribution:32 ‘A’ fuses (30 Amp)32 ‘B’ fuses (30 Amp) - for feeding fuse panels in equipment bays.

244

POWERMain Power Board

• measures voltage & current used by office– Shunt - measures current - ammeter

• provides main fuses to powersecondary distribution boards

• may provide distribution fuses fortransmission racks (remote)

• provides a 'battery return' bus forbattery grounds

Shunt

Voltage Current

Fuses

245

Shunt – used to measure office current

Shunt - Measures current by measuring voltage. - provides protection for power plant - plates heat up & fall out or burn up Measured Current = Voltage drop across shunt Resistance plates - known, accurate

individual plates

246

POWERSecondary Power Distribution

BoardsSwitching – PDC

- Power Distribution Center– located in switching lineup

Transmission - BDFB - Battery Distribution Fuse Board– located in transmission equipment area

Voltage Current

247

Nortel SwitchingPDC

Power Distribution Centerfor digital switch

248

POWERTransmission Distribution Power

Board• provides secondary power distribution

to transmission racks• may be fuses or breakers• A & B sides - 2 Shunts, 2 voltmeters,

2 ammeters• powers A & B battery & ground to

fuse panels with 2 power inputs• distribution fuses typically 10 to 30 Amp

• requires two 600-Amp fuses from MainPower Board for diversity protection

A-side

B-side

Voltage Current

shunt shunt

Fuses or breakers

249

Main Power Board feedingTransmission Power Board

Main Power Board

Transmission Power Board

‘A’ side

‘B’ side

BDFB

shunt

Voltage Current

To TransmissionRacks to Powerfuse panels.

30-70 Amp fuses / breakers600 Amp fuses

Voltage Current

shunt shunt

-48V

250

Power DistributionDual power feeds with ground

BDFB

-48V

‘A’ side

‘B’ sideEquipment

Rack

BDFBGround Bar

Battery plant Ground Bar

TelephoneEquipment

Fuse panel

Main Power Board

Ground leadsGround

cable

shunt

Voltage CurrentVoltage Current

Shunt Shunt Shunt

251

TransmissionDistributionPower Board

Meter Panel for A & B sides30 Amp breakers

A side Distribution

B side Distribution

Power cablesFeeding powerBoard, and Powering otherEquipment.

252

Remote buildingPower Boardwith Rectifiers

Two Rectifiers,100-Amp each- Load not toexceed 100

Amps (Maximum load

+1 rectifier)

Meter panel

Main Distribution panelSecondary Distribution panel

Shunt panel

Secondary Distribution panel

253

Batteries

RectifierAC to DC

Batteries Power Board Main or Distribution

- -- +

+-48V -48V

ToC.O.

equipment

+

Common bus for (+) & ( -)

-48VAC

AC

DC DC

3-hour backup with Generator8-hour backup without Generator

C.O. ground bus

Shunt

Voltage Current

254

Batteries24 Cells-48 Volts nominal-52 Volts Charge

voltageWet Cell -

lead calcium 20 -25 year life

255

Batteries- Sealed ‘Dry’ cells- Valve Regulated- GNB “Absolyte” has Absorbent glass mat.- 20 year life

256

Backup Generator• provides electrical power to run the office in event of A/C

power failure - typically 7.5 kW to 60 kW units

• larger sizes for main central offices – 250kW to 750kW+

• runs on propane (older installations) or diesel fuel (newerinstallations.

Shown is a365 kW dieselGenerator.

257

AC Transfer SwitchCommercial AC Power

Backup Generator

AC Load

Automatic Transfer Switch

To: rectifiers air conditioning lights

Normal

Emergency

258

GroundingKeep People & Equipment Safe from Lightning

4 Grounding Elements:– Producers– Absorbers– Isolated Ground Zone - IGZ– Non-Isolated Ground Zone - Non-IGZ

259

Grounding

Producers – anythingthat allows lightninggets into a telephoneoffice.– sheath of cables

entering office– firing point of protector

modules– radio towers

Outside plantCopper cable

MDF protectors

Grounding pointsconnected to ground bar

260

Grounding

Absorbers – anythingthat absorbs alightning surge.– ground field around

office - 5 ohm grounddesired

– building structure /metal water pipes

Telephone Office

Ground field/ring – 8-foot deep ground rods buried 8-feet apart

261

Grounding

• •

• •

• •

• •

Producer Absorber Non-IGZ IGZ

Master Ground Bar – MGB

262

Master Ground Bar - MGB

Producers Absorbers Non-IGZ IGZ

P.A.N.I. bar

263

GroundingIGZ

IGZ - Isolated Ground Zone– All cards in equipment bays are isolated from

the bay ironwork.Digital switch has a separate IGZ bus bar -

Ground Window Bar - GWB– GWB connects to IGZ zone on MGB

• •

• •

Ground Window Bar - GWB

MGBTo IGZ(digital switch)

264

GroundingNon-IGZ

Non-Isolated Ground ZoneTransmission equipment:

– May not have the cardsisolated from the shelves

– May not have the shelvesisolated from the bays

– i.e. the cards & shelves maybe grounded to the ironworkwhich violates the IGZ concept


Fuse panel


Rack

Cardsshelf

265

OSP fiber cable

MDF

ISDN


Dig

ital s

witc

h

LGX

D4 ChannelBank

HDSL


DSX-3DSX-3

DS1

DS1

DS1

DS1

DS1

DS1

DS1

HDSL DS1


VF signal

2B + DBRI

DS3

DS3

fiberjumpers

coaxialcable

coaxialcable

OutsidePlant cables

DSX-1DSX-1DSX-1

DCS1/0


Introduction to Telephony Basics

Documents

special circuitsvoice grade

fiber optic terminal

d4 channel bank24

main distribution frame

osp fiber cable

d4 channel bank

copper cable facilities

entire bit stream