cable handbook revised

Prepared Fayyaz Ahmad Sheikh SE Engineering Cable May 10, 2005 Colour Scheme Reinhold Mueller Com Engineer Central May 11, 2005 Reviewed Mohamed Barray Course Developer May 16, 2005 Checked Juergen Fiebach Manager Operation May 16, 2005 Approved Johann Graf Project Manager May 16, 2005

Revised Fayyaz Ahmad Sheikh SE Engineering Cable 10 October 2007

Christian Menzel Manager Operation 13 October 2007 Checked

Torsten Maass Manager Engineering 16 October 2007

Approved Juergen Fiebach Project Manager 18 October 2007

DETECON AL-SAUDIA CO. LTD LDTN Project

Handbook On

Fibre Optic Cable Maintenance

___________________________________________________________________________________ DETASAD TRAINING CONFIDENTIAL of 55

Content:

1. DEFINITION OF FIBRE OPTIC.......................................................................5

1.1 BASIC CONSTRUCTION OF OPTICAL FIBRE .........................................................5 1.2 CONSTRUCTIONAL DETAILS OF FIBRE OPTIC CABLE ........................................6 1.3 TYPES OF FIBRE OPTIC CABLES ..........................................................................7

2. DEFINITIONS OF TERMS USED IN FIBRE OPTIC CABLE......................8

2.1 TERMINATIONS.....................................................................................................8 2.2 SPLICING.............................................................................................................10 2.3 TEST EQUIPMENT ...............................................................................................10 2.4 MEASUREMENTS.................................................................................................10 2.5 UNITS, POWER PREFIXES ...................................................................................11

3. FIBRE OPTIC TOOL KIT AND ACCESSORIES.........................................12

3.1 LIST AND PICTURES OF TOOLS ..........................................................................12

4. FIBRE OPTIC SPLICING ................................................................................15

4.1 MECHANICAL SPLICING:....................................................................................15 4.2 FUSION SPLICING: ..............................................................................................15 4.3 PREPARATION OF FIBRE OPTIC CABLE FOR SPLICING.....................................15 4.4 OPTICAL FIBRE SPLICING PROCESS ..................................................................15

5. TESTING OF FIBRE OPTIC LINK ................................................................16

5.1 TOOLS AND TEST EQUIPMENT FOR THE JOB .....................................................16 5.2 MEASUREMENT OF OPTICAL POWER & LOSS...................................................16 5.2.1 MEASURING POWER ..........................................................................................16 5.2.2 TESTING LOSS...................................................................................................16 5.2.3 REFERENCING OPTICAL LOSS TEST UNIT..........................................................17 5.2.4 FIBRE LOSS VARIABLES....................................................................................20 5.2.5 CALCULATING LINK LOSS.................................................................................21

6. OTDR TRACE ANALYSIS...............................................................................22

6.1 OTDR PARAMETERS..........................................................................................23 6.1.1 WAVELENGTH...................................................................................................23 6.1.2 INDEX OF REFRACTION.....................................................................................23 6.1.3 PULSE WIDTH OR DURATION ............................................................................23 6.1.4 RANGE OR DISTANCE........................................................................................24 6.2 DEAD ZONE: .......................................................................................................24


7. CLEANING OF CONNECTORS .....................................................................25

7.1 INSPECTION AND CLEANING PROCEDURE .........................................................25 7.2 DRY CLEANING METHODS.................................................................................26 7.3 WET CLEANING METHODS ................................................................................27

8. SPECIFICATIONS AND PROCEDURES FOR CABLE INSTALLATION & REPAIRS................................................................................................................28

8.1 CABLE DEPTH.....................................................................................................28 8.2 SPLICE POINTS....................................................................................................29

9. POINTS TO REMEMBER................................................................................31

9.1 SAFETY FIRST!....................................................................................................31 9.2 ZERO TOLERANCE FOR DIRT.............................................................................31 9.3 TOOLS AND MATERIALS.....................................................................................32 9.4 DOCUMENTATION AND RECORD MAINTENANCE ..............................................32

10. CHECK LIST AND PROCEDURES FOR FINAL REPAIR / RELOCATION OF FIBRE OPTIC CABLE..........................................................33

10.1 CIVIL WORKS & PREPARATION IN THE FIELD .................................................33 10.2 ORGANIZING MDT/TC....................................................................................33 10.3 LIST OF TOOL & TEST EQUIPMENT..................................................................34 10.4 STAFF ARRANGEMENTS ...................................................................................34 10.5 EXECUTION OF TC/MDT................................................................................35 10.6 TEST REQUIRED ...............................................................................................36 10.7 PRIORITY OF SYSTEMS .....................................................................................36 10.8 EMERGENCY REPAIR PROCESS........................................................................37

11. GUIDELINES FOR OPENING AND UPDATING OF THREATENING TROUBLE TICKETS. ..............................................................................................38

11.1 UPDATES RELATED TO MONITORING OF ACTIVITIES BY THIRD PARTIES ON OR NEAR TO THE CABLE:...................................................................................................38 11.2 UPDATES RELATED TO RELOCATION ACTIVITIES BY THIRD PARTIES:............42 11.3 UPDATES RELATED TO MDT’S EXECUTED BY THIRD PARTIES FOR RELOCATION PROJECTS. ............................................................................................44

12. CABLE ROUTE MARKER POSTS...............................................................45

12.1 TYPES OF CABLE ROUTE MARKERS POSTS.....................................................45 12.2 INSTALLATION OF CABLE ROUTE MARKERS POSTS.......................................45

13. RELOCATION OPTIONS ..............................................................................46


14. GUIDELINES FOR 3RD PARTY MDT/TC’S EXECUTED ON EXISTING FIBER OPTIC CABLES ......................................................................48

15. PHYSICAL CABLE LOCATION ..................................................................49

15.1 INTRODUCTION.................................................................................................49 15.2 BASIC THEORY. ................................................................................................49 15.3 APPLYING THE SIGNAL.....................................................................................50 15.3.1 CONDUCTIVE / DIRECT CONNECTION METHOD ...............................................51 15.3.2 INDUCTIVE METHOD........................................................................................52 15.3.3 INDUCTIVE CLAMP METHOD ...........................................................................53 15.4 TRACING OF CABLE..........................................................................................53 15.5 ADJUSTING THE GAIN ......................................................................................54

16. COLOUR SCHEME.........................................................................................55

Figures: Figure 1: Basic construction of optical fibre..................................................................5 Figure 2: Constructional Details of Fibre Optic Cable ..................................................6 Figure 3: Single Ended Loss ........................................................................................17 Figure 4:Double Ended Loss Measurement / FASTEST SETUP ..............................17 Figure 5: Loop Back Method.......................................................................................18 Figure 6: Side by Side Method ....................................................................................19 Figure 7: OTDR Trace Analysis ..................................................................................22 Figure 8: Cable Trench ................................................................................................28 Figure 9: Arrangement for splicing at site ...................................................................29 Figure 10: Arrangement of splice enclosures ..............................................................30 Figure 11: Arrangement of Buried Splice....................................................................30 Figure 12: Information for 1st update of Threatening Trouble Ticket .........................39 Figure 13: Working Area of Third Party .....................................................................40 Figure 14: Information for Trouble Ticket update during course of activity ..............41 Figure 15: Information for Trouble Ticket update during course of activity ..............41 Figure 16: Information for Final update of Threatening Trouble Ticket.....................42 Figure 17: Types of Cable Route Marker Posts...........................................................45 Figure 18: Marker Post Placement...............................................................................45 Figure 19: Relocation Option-1 ...................................................................................46 Figure 20: Relocation Option-2 ...................................................................................46 Figure 21: Cable Locator Direction Connection..........................................................51 Figure 22: Cable Locator Inductive Method................................................................52 Figure 23: Cable Locator Inductive Clamp Method ....................................................53 Tables: Table 1: List of Tool Kit ..............................................................................................14 Table 2: Attenuation Criteria .......................................................................................21 Table 3: Depth of Buried Fibre Optic Cables ..............................................................28


1. Definition of Fibre Optic Fibre Optic is a thin strand of highly transparent glass or plastic that guide light. It is used as a medium for carrying information from one point to another in the form of light. A basic fibre optic link consists of a transmitting device, which generates the light signal; an optical fibre cable, which carries the light; and a receiver, which accepts the light signal transmitted. The fibre itself is passive and does not contain any active properties

1.1 Basic Construction of Optical Fibre

Figure 1: Basic construction of optical fibre

Core: The centre of the fibre through which the light is transmitted Cladding: The outside optical layer of the fibre that traps the light in the core and guides it along and even through curves Buffer coating or primary coating: A hard plastic coating on the outside of the fibre that protects the glass from moisture or physical damage. Fibre optic cable functions as a "light guide," guiding the light introduced at one end of the cable through to the other end. The core and cladding are manufactured together as a single piece of silica glass. The core region’s refractive index is greater than the cladding layer. The glass does not have a hole in the core, but is completely solid throughout. The light is "guided" down through the core. The cladding traps the light in the core using an optical technique called "total internal reflection.” The third section of an optical fibre is the outer protective coating called the "primary buffer coating". This coating is typically an ultraviolet (UV) light-cured acrylate applied during the manufacturing process to provide physical and environmental protection for the fibre. During the installation process, this coating is stripped away from the cladding to allow proper termination to an optical transmission system.

Coating 250µm

Core

Cladding

Coating

Core 8.3 ~ 9µm

Cladding 125µm

Cross Sectional View of a Single Mode Fibre Side View of a Single Mode Fibre


1.2 Constructional Details of Fibre Optic Cable

Figure 2: Constructional Details of Fibre Optic Cable

Rip Cord

Water Blocking Material (Jelly)

Outer Sheath (Jacket) Double Layer for Direct Buried & Single Layer for Duct Cable

Steel for Grounding

Thread & Paper

Dielectric Strength Element (Kevlar)

Central Strength Member

Optical Fibres Gel-Filled Buffer Tube

Outer Sheath (Jacket)

Steel sheath for Grounding

Dielectric Strength Element (Kevlar)

Thread and Paper

Gel Filled Buffer Tubes

Central Strength Member

Optical fibres


1.3 Types of Fibre Optic Cables There are two types of fibre optic cable commonly used: 1. Multi Mode Cables: Over the years a variety of core sizes have been produced

but these days there are only two main sizes for Multimode fibres. These cables are most widely used in data networks. The numbers 50/125 & 62.5/125 represent the diameters of the fibre core and cladding; these are measured in microns, which are millionths of a metre

2. Single Mode Cables: Single Mode cable has a core diameter of 8.3 to 10 microns.

It is the most commonly used cable in Telecommunication for transmission systems. The numbers 8.3/125 represent the diameters of the fibre core and cladding

Note: Both multimode and single mode fibres have an outside diameter of 125 microns - about 5 thousandths of an inch - just slightly larger than a human hair.


2. Definitions of Terms used in Fibre Optic Cable

2.1 Terminations

Patch panels Provides a centralized location for patching fibres, testing, monitoring and restoring cables.

Connector

A non-permanent device for connecting two fibres or fibres to equipment where they are expected to be disconnected occasionally for testing or rerouting. It also provides protection to both fibres.

Ferrule A tube, which holds a fibre for alignment, usually part of a connector

SC connector : SC Stands for Single Coupling. It is a Square shaped snap-in connector that latches with a simple push-pull. The SC connector has the advantage (over ST) of being duplexed into a single connector clip with both transmit/receive fibres

SC/UPC SM connector, Pre-Dome 125um ferrule

SC/APC SM connector Pre-Angle Cone 125um ferrule

FC Connector: The FC stands for "Face Contact" The anti-rotation key prevents fibre end face damage and rotational sensitivity and the floating ferrule prevents shock and vibration.

FC/UPC SM connector , Pre-Dome 125um ferrule

FC/APC SM Connector Pre-Angled 125um ferrule


ST Connector : ST Stands for Straight Tip. The ST connector is spring-loaded bayonet mount and have a long cylindrical ferrule to hold the fibre

ST/UPC SM Connector Pre-Dome 125um ferrule

LC Connector : LC stands for Latched Connector and it’s interconnect is based upon the RJ-45 telephone interface. The LC Connector uses Zirconium ceramic ferrules in a free-floating and pull proof design.

LC SM Simplex connector, with 125 ferrule

LC SM Duplex connector , with 125 ferrule

LC SM Duplex connector, with 125 ferrule

MU Connector : The MU stands for Miniature Unit fibre-optic connector, which features compact size, high packaging density, and high performance and a simple push-pull design. The MU connector ferrules are half the size of the standard FC, SC connectors and are excellent for high-density installations.

MU SM Connector Compact - Miniature Body-Stable, reliable,

PC Connector Physical Contact Connector FPC Connector Flat Physical Contact Connector APC Connector Angled Physical Contact Connector SPC Connector Super Physical Contact Connector UPC Connector Ultra Physical Contact Connector


2.2 Splicing Splice enclosures For long cable runs outside, the point where cables

are spliced sealed up and buried in the ground, put in a vault of some kind or hung off a pole.

Splice panels Connect individual fibres from cables to pigtails Mechanical Splice A splice where the fibres are aligned by mechanical

means Fusion Splice A splice created by fusing two fibres together Fusion Splicer An instrument that splices fibres by fusing them,

typically by electrical arc

2.3 Test Equipment

Optical Power Meter An instrument that measures optical power from the end of a fibre

Laser Source An instrument that uses a laser or LED to send an optical signal into fibre for testing loss of the fibre

Optical Loss Test Set (OLTS)

A measurement instrument for optical loss that includes both a power meter and laser source

Reference Test Cables Short, single fibre cables with connectors on both ends, used to test unknown cables.

Mating Adapter Also called couplers, allow two cables with connectors to mate.

Optical Microscope Used to inspect the end surface of a connector for dirt.

2.4 Measurements

Attenuation The reduction in optical power as it passes along a fibre, usually expressed in decibels (dB).

Bandwidth The range of signal frequencies or bit rate within which a fibre optic link or network will operate.

Chromatic Dispersion

A property of optical fibre due to which different wavelengths travel at different speeds and arrive at different times, resulting in spreading of a pulse in an optical wave guide.

Decibels (dB) A unit of measurement for optical power, which indicates relative power. A -10 dB means a reduction in power by 10 times.

dBm Absolute Power, Optical power referenced to 1 milliwatt

Nanometer (nm) A unit of measure used to measure the wavelength of light (meaning one-billionth of a meter)

Optical Loss The amount of optical power lost during transmission of through fibre, splices, couplers, etc. expressed in dB.

Optical Power It is measured in "dBm", or decibels referenced to one milliwatt of power. While loss is a relative reading, optical power is an absolute measurement,


referenced to standards. Absolute power is measured to test transmitters or receivers and relative power to test loss.

Back Reflection Light reflected from the cleaved or polished end of a fibre caused by the difference of refractive indices of air and glass.

Power Budget The total amount of power lost in the link. Often used in terms of the maximum amount of loss that can be tolerated by a given link.

Polarization Mode Dispersion

The spreading of a pulse in an optical wave guide by virtue of different light paths lengths is called Modal dispersion.

Refractive Index A measure of the speed of light in a material, a property of optical materials that relates to the velocity of light in the material

Scattering The change of direction of light after striking small particles that causes loss in optical fibres and is used to make measurements by an OTDR

Wavelength

A term for the colour of light, usually expressed in nanometres (nm) or microns (m). Fibre is mostly used in the infrared region where the light is invisible to the human eye.

2.5 Units, Power Prefixes Prefix Symbol Factor tera T 1012 giga G 109 mega M 106 kilo k 103

hecto h 102 deka da 101 deci d 10-1 centi c 10-2 milli m 10-3 micro µ 10-6 nano η 10-9 pico p 10-12


3. Fibre Optic Tool Kit and Accessories Toolkit provides the cable technician with a collection of essential tools required for the installation, maintenance and termination of Fibre Optic Cables. The essential tools listed below includes everything required to perform rapid emergency repairs to damaged fibre optic cables as well as to perform permanent repairs of fibre optic cables.

3.1 List and Pictures of Tools

S. No. Description Picture

1 RXS Cleaver

2 3M 2501 Fiberlok Assembly Tool

3 Cable Cutter

4 Side Cutter Pliers (Small)

5 Side Cutter Pliers

6 Pliers

7 Fibre Cable Jacket Slitter (Longitudinal)


8 Fibre Cable Jacket Slitter (Round)

9 Kevlar Electrician Scissor

10 Buffer Tube Stripper

11 Buffer Tube Stripper Pliers type

12 Fibre Stripper Pliers Type

13 No-Nik Stripper

14 Tweezers

15 Cleaning Tape

16 Utility Knife

17 Measuring Tape 3”

18 Screw Drivers Set Philips & Flat


19 Adjustable Wrench 4"

20 Number Markers

21 Compressed Air Jet Cleaner

22 Nylon Cable Ties (Assorted)

23 Permanent Marker

24 Alcohol Swabs

25 Electrician's Tape

26 Flash Light

27 Kimwipes

Table 1: List of Tool Kit


4. Fibre Optic Splicing There are two methods of fibre optic splicing, fusion splicing & mechanical splicing. Mechanical splicing is usually carried out for emergency restorations whereas fusion splicing is done for permanent repairs of damaged cable or to connect the reels of cable during installation

4.1 Mechanical Splicing: Mechanical splices are simply alignment devices; designed to hold the two fibres ends in a precisely aligned position thus enabling light to pass from one fibre into the other. (Typical loss: 0.3 dB)

4.2 Fusion Splicing: Fusion splicing is the joining and fusing of two fibres by placing them between two electrodes, and discharging an electric arc over the fibres. This splice technique is non-reflective. Fusion splicing machine is used to precisely align the two fibre ends then the glass ends are "fused" together using electric arc. This produces a continuous connection between the fibres enabling lower loss and less back reflection than mechanical splicing because the resulting fusion splice points are almost seamless. (Typical loss: 0.1 dB)

4.3 Preparation of Fibre Optic Cable for Splicing 1 Removal of outer jacket: Remove the fibre optic cable's protective jackets and

buffers to allow access to the optical fibre. Make sure the cutting members are not

damaging the buffer tubes.

2 Cutting of Kevlar: The Kevlar can be trimmed using scissors or Kevlar cutters.

3 Cleaning of Buffer Tubes: Clean the jelly on buffer tubes with isopropyl wipes.

4 Fixing of cable in the enclosure: The cable should be fixed in the enclosure

according to the recommendations of the manufacturer of the splice enclosure.

5 Stripping of Buffer Tubes: The buffer tubes, like the outer jackets, can be

removed by stripping tools. Care must be taken to avoid kink or damage to

internal coated fibres.

4.4 Optical Fibre Splicing Process 1. Stripping : Once the coated fibre is exposed, Use fibre stripper to strip fibre to

appropriate length. Take care not to damage the fibres in the process.

2. Cleaning: After the coating is removed, clean the fibre with specially designed

isopropyl alcohol wipes so that the fibre squeaks.


3. Cleaving: A good cleave is the key to obtaining a good splice. Use cleaver to cut

the fibre. After cleaving do not touch or clean the fibre.

4. Splicing: The fibre is now ready to be spliced mechanically or Fusion. Insert the

fibre carefully in the mechanical splice or in the fusion splicer for splicing. While

inserting in the mechanical splice make sure that fibre is inserted directly in the

groove and do not touch any other surface. Fusion splicer will automatically align

and fuse the fibre.

5. Protection: In case of fusion splicing cover the splice with heat shrink sleeve and

place it in the heater, for mechanical splice carefully close the mechanical splice.

6. Organizing: Organize the fibre in the enclosure properly Make sure that

organising do not cause Micro-bending.

5. Testing of Fibre Optic Link Cables need to be tested for Continuity, End-to-End Loss and any other potential problems. For long outside plant cables with intermediate splices, all individual splices need to be verified with an OTDR, since that's the only way to make sure that each one is good. Within the network testing for power is necessary as power is the measurement that tells whether the system is operating properly.

5.1 Tools and Test Equipment for the job 1. Source and power meter, optical loss test 2. Reference test cables 3. Cleaning materials - lint free cleaning wipes and pure alcohol 4. OTDR and launch cable for outside plant jobs

5.2 Measurement of Optical Power & Loss There is a difference between the power coupled into a component like a cable or a connector and the power that is transmitted through it. This difference is what we call optical loss and defines the performance of a cable, connector, splice, etc.

5.2.1 Measuring power Power in a fibre optic system is like voltage in an electrical circuit. To measure power, attach the meter to the cable that has the output you want to measure. Turn on the transmitter/source and note the power the meter measures.

5.2.2 Testing Loss Following two methods are used to measure loss. Optical Loss Test Sets contains a light source and power meter in the same unit. For both methods two units of loss test sets (one at each end of the fibre under test) are required.


1. Single Ended Loss (Laser Source and Power Meter) This test is initiated from one end and result is displayed at far end unit.

Figure 3: Single Ended Loss

2. Double Ended Loss (FasTest Method) In this test Laser source is initiated from one end and the results are displayed at both ends simultaneously. Both test method measure the loss of two ODF connectors (one on each end), the loss of cable and splices in between. Most commonly FASTTEST set-up method is used for loss testing. _______________________________

Figure 4:Double Ended Loss Measurement / FASTEST SETUP

5.2.3 Referencing Optical Loss Test Unit Prior to perform loss test measurement, a reference measurement must be stored in both units. The reference measurement includes the loss caused by the test set-up components including test Patch cords. The unit will store a reference reading of power level at the end of test Patch cord. This reference measurement is subtracted

Fiber Optic Link under Test

Test Patch Cord Test

Patch Cord

Optical Loss

Test Set

Receiver Transmitter

Optical Loss

Test Set

Detector Port

Source / FasTesT

Port

Detector Port

Source / FasTesT

Port

Test Patch Cord

Transmitter

Optical Loss

Test Set

Fiber Optic Link under Test

Test Patch Cord

Measurement SETUP

Optical Loss

Test Set

Receiver

Detector Port

Source / FasTesT

Port

Detector Port

Source / FasTesT

Port


from the overall loss so the final loss result represents the loss of system under test alone. There are two referencing methods in practice for Loss test sets and both results in accurate loss measurement:

Loop-back Method with only one test jumper Side-by-Side Method with two test patch cords and a mating adapter

1. Loop back Method

Figure 5: Loop Back Method

The main advantage of the loop back referencing method is that there is no need to bring both units at same location. This is performed by connecting a single test patch cord from the unit’s Source Port (FASTTEST Port) to Detector Port. 1. After performing the loop-back reference, simply disconnect the test patch cord

from the Detector Port and connect it to the ODF of Fibre link Under Test. 2. It is very important not to disconnect it from the source port (FASTTEST Port)

because the amount of light coupled or injected into the test patch cord varies from one connection to another.

3. If the test patch cord is disconnected from the source port, it is required to repeat

the references. 4. The loop-back test is performed individually on each of the two units. 5. An important advantage of the loop-back method is that it automatically takes into

account the loss of the test patch cord and Mating adapters, allowing a true measurement of the fibre itself.

Optical Loss

Test Set

Source / FasTesT Port Not to be disrupted once

the reference is set.

Detector Port, Disconnect this end and connect to ODF of FO link under Test

once the reference is set


2. Side-by-Side Method To perform the side-by-side reference procedure, two test patch cords are connected via a Mating adapter and then connect the test patch cord ends to the Source Port (FASTTEST Port) of both units.

Figure 6: Side by Side Method

1. When using the side-by-side reference method, both units must be brought to a common site to take the appropriate references.

2. Once the side-by-side reference is performed, disconnect the test jumpers at the

Mating Adopter and connect both test jumpers to the ODF of Fibre Link Under Test.

3. Much like the loop back reference, it is very important not to disconnect the test

jumper from the source port as the amount of light coupled or injected into the test patch cord will vary from one connection to another. If the test patch cord is disconnected from the source port (FASTTEST Port), it is required to repeat the reference

Note: Before measuring optical loss with an automated OLTS, referencing is a crucial procedure that should be performed before every test session.

Performing FasTesT: The purpose of a FasTesT is to test the fibre according to set parameters with minimum intervention by the persons involved in test. Although the FasTesT is performed with two units, one at each end of the fibre, it is initiated from only one unit and the result will be displayed at both units

Optical Loss

Test Set

Source / FastTesT Port Not to be disrupted once

the reference is set

Optical Loss

Test Set

Detector Port / Power Meter Port

Mating Adapter Disconnect here to connect to ODF of FO link Under Test

Receiver Transmitter


5.2.4 Fibre Loss Variables i. Attenuation

All fibre has losses from absorption and back reflection of the light caused by impurities in the glass. Attenuation is a function of wavelength and needs to be specified or measured at the wavelength in use.

ii. Modal Dispersion

The higher the data rate, the shorter the distance the signal can travel before modal dispersion creates an inability to accurately detect the signal (i.e. a "1" from a "0").

iii. Chromatic Dispersion

Another dispersion effect, which causes pulse spreading, and limits distance is chromatic dispersion, where the broader spectrum of light can result in varying travel times for different parts of a light pulse.

iv. Splices

Although small and often insignificant, there is no perfect loss-less splice. Many errors in loss calculations are made due to a failure to include splices. Average splice loss is usually less than 0.1 dB.

v. Connectors

Like splices, there is no perfect loss-less connector. It is important to note that even the highest quality connectors can get dirty. Dirt and dust can completely obscure a fibre light wave and create huge losses. A 0.5 dB loss per connector is commonly the worst-case scenario assuming a cleaned and polished connector is used. There will always be a minimum of two connectors per fibre segment, so remember to multiply connector loss by two.

vi. Safety Buffer

It is common to add a loss as a design margin. Allowing 2 - 3 dB of loss can take fibre aging, poor splices, maintenance margin, temperature and humidity, etc., into account and ensures a solid system.

NOTE: To determine minimum/maximum losses and maximum distances you need to identify all of the above variables. Failure to identify even one of these variables can create potential problems Terminology


5.2.5 Calculating Link Loss Losses occur at many points in a fibre optic system. We have to ensure that the light source launches enough power into the fibre to provide enough power at the receiver. The receiver has limited sensitivity. Transmitter output - Receiver input = Losses + Margin (All calculations are done in dB) For single mode fibre cable with two most commonly used wavelengths— 1310 nm and 1550 nm—The attenuation measurement will vary depending upon which wavelength is in use. Attenuation is measured in dB and is quoted as attenuation in dB/km. Under mentioned is the most commonly used method to determine the maximum signal loss across a piece of pre-existing fibre (Link Loss)

Loss/Km Loss in dB Connector Splice Optical

Fibre Type 1310nm 1550nm In dB Single Mode 0.35 0.23 0.50 0.09

Table 2: Attenuation Criteria

The measured value of attenuation of a FO link should not exceed the sum of allowable attenuation of each component. These components are: • The Fibre Optic cable • The FO connectors • The Splices

Link Loss (dB) = Cable Loss + Connector Loss + Splice Loss + (Safety Margin)

Cable Loss = Cable length (Km) x Attenuation Coefficient (db/Km) Connector Loss = Number of Connector Pairs x Connector Loss (dB) Splice Loss = Number of Splices x Splice Loss (dB) (Safety Margin / Maintenance Margin ) = 2 ~ 3 dB depending upon the length of link


6. OTDR Trace Analysis

Figure 7: OTDR Trace Analysis

Reflective Event Dead Zone

Reflective Event Loss

Dead Zone

Launch Level

Non-Reflective Event Loss

Non-Reflective Event Loss caused by Macro-Bending

Non-Reflective Event (Fusion Splice, Bend)

Non-Reflective Event (Macro Bend)

Noise

Out Put End-Face Reflection

In-Put End-Face Reflection

Dead Zone Dynamic Range

Reflective Event (Connector, Mechanical Splice, crack)

Distance (M)0 M

dB

End-

to-E

nd L

oss


6.1 OTDR Parameters There are four main settings that the technician must set correctly on the OTDR before testing. Those are Wavelength, Index Of Refraction, Pulse Width and Distance

6.1.1 Wavelength The behaviour of an Optical system is directly related to the wavelength of transmission. Not only Optical fibre will exhibit different loss characteristics at different Wavelengths, but splice loss value also differ at different wavelengths. In general fibre should be tested with both wavelengths i.e. 1310 and 1550nm for single mode fibres. If testing is only to be performed at one wavelength it should be done with 1550nm considering the following points.

1550nm will see longer distances down the fibre due to the lower attenuation as compared t0 1310nm

1550nm is more sensitive to losses incurred by bending during installation and

organising of fibres in the splice enclosures after splicing

6.1.2 Index Of Refraction The index of refraction sets the OTDR to the proper speed of light for a particular fibre link being tested.

Changing the IOR value will change the distances to events on the OTDR trace, and also the overall length of the fibre.

The IOR of a particular fibre is usually provided by the manufacturer

6.1.3 Pulse Width or Duration This is another setting that must be selected to receive the clearest information from the OTDR trace. The length of time that the OTDR's laser is turned on is called the "pulse width". As the OTDR turns the laser on and off, the duration of the laser being “on” results in a pulse of a certain length.

Shorter pulse widths provide better traces of events that are close together, as the shorter pulse widths will have shorter “dead” zones after reflective events. However, short pulse widths will result in a noisy, hard to interpret trace for long distance fibre link, as the OTDR process weaker returned signals.

Long pulse widths means more light energy is injected in the fibre. The more light

injected means the more light is reflected back from the fibre to OTDR. It causes longer “dead” zones, and reduces resolution of events that are close to each other. Long Pulse width is therefore used to see long-distance down a cable.


The General Rule to set Pulse width is:

Short Fibre Link = Short Pulse Width

Long Fibre Link = Long Pulse Width

Shorter pulse widths can be used on longer fibre links to give greater detail to

events close to the OTDR and for fault analysis.

6.1.4 Range or Distance The range on an OTDR is the maximum distance that OTDR will acquire data samples. This parameter is generally set at twice the distance of the end of the fibre Note: Neglecting to set any of these parameters properly can result in wrong reporting by the OTDR

6.2 Dead Zone: The OTDR is designed to detect the back scattering level all along the fibre link. It measures the back-scattered signals, which are much smaller than the signal sent to the fibre. When there is a strong reflection then the power received at the OTDR is much higher than the backscattered power, which saturates the OTDR. OTDR requires time to recover from the saturated condition. During this time OTDR cannot detect the backscattered signal accurately. The length of fibre, which is not fully characterized during the recovery period, is termed as dead zone. This affect is similar to the one when we are driving a car at night and that another car’s headlight dazzles our vision momentarily. The dead zone depends on the pulse width, the reflectance, the loss and the location


7. Cleaning of Connectors

CAUTION:-

Lasers used in telecommunication systems are powerful enough to burn contaminants into the fibre end face. Always ensure the laser is turned off while performing the cleaning procedure.

Warnings:-

Do not look into a fibre while the system laser is on.

Do not connect a fiberscope while the system laser is on.

Do not use alcohol or other wet cleaner without a way to ensure that all residues are removed.

Do not touch the end face of the fibre connector.

Install dust caps on unplugged connectors

Store unused dust caps in a container to prevent dust on the caps from being

transferred to the fibre end.

Do not re-use swabs or cleaning tissues.

Proper cleaning of connectors is very important. The core diameter of a single-mode fibre is only about 9um. This generally means you cannot see streaks or scratches on the surface.

There are three critical steps to ensure high quality optical connections.

1. Inspection

2. Cleaning

3. Re-inspection

7.1 Inspection and Cleaning Procedure

The following are general steps that should be performed for cleaning fibre optic patch cord connectors.

1. Inspect the fibre end with a fiberscope.

2. If the fibre end is contaminated, clean using a dry cleaning method.


3. Inspect the connector again using the fiberscope.

4. If the fibre end is still contaminated, attempt the dry cleaning method again.


6. If the connector is still contaminated, clean using a wet cleaning method immediately followed by a dry cleaning method to remove all residues.


8. Repeat this process until the end face is clean.

9. If the fibre end cleaning is unsuccessful, the contamination may be due to scratching, improper polishing, or other damage. If possible, this fibre should not be used.

7.2 Dry Cleaning Methods

For dry cleaning method, use Cletop cleaner.

1. Move the thumb lever to expose the cleaning cloth. Each time the lever is pressed, a clean section of cloth is exposed.

2. Holding the fibre end perpendicular to the cleaning cloth, twist 90 degrees and then drag down across the exposed cleaning cloth applying a small amount of pressure.

(View diagram on Cletop)

3. Do not re-use the same section of cleaning cloth once a fibre end has been cleaned. To expose a new section of cleaning cloth, release the thumb lever, then actuate the lever again.

4. Inspect with fiberscope.


7.3 Wet Cleaning Methods

If the dry cleaning method does not adequately clean the connector, using isopropyl alcohol swabs. Remember that isopropyl alcohol is not very quick drying and leaves residue.

1. Holding the fibre connector perpendicular to the swab, twist and wipe the end face several times.

2. Repeat the twist and clean with CLETOP cleaner as explained above.

3. Inspect the end face.

Note: Do Not Forget to clean the connector with cleaning tape after cleaning it with isopropyl alcohol swab. L


8. Specifications and procedures for Cable Installation & Repairs

8.1 Cable Depth The depth at which buried cable can be placed will vary with local conditions i.e. Type of soil and Terrain. However fibre optic cable must be buried at a minimum depth of 80 cm.

Location Depth Soft Soil 80 ~ 130 cm Hard Soil / Rock Soil Minimum 80 cm Road Way crossing Minimum 110 cm

Table 3: Depth of Buried Fibre Optic Cables

Under mentioned diagram shows the typical layout of Direct Buried cable.

Figure 8: Cable Trench

Soft Sand

Legend

Back filling

Undisturbed Earth

20 cm

20 cm Soft Sand

Soft Sand

40 ~90 cm

80 ~130 Cm

Back filling

Fibre Optic Cable

Soft Sand

Soft Sand

Back filling

Warning Tape

Front ViewSide View of Trench


In certain installation areas, for example, rights-of-way with limited access (public highways, private property boundaries, water ways, Culverts and under the bridges, cable must be buried in a duct and if such constructions are done after the installation of cable, Fibre Optic cable must be protected in the affected area with PVC pipe, iron barring and concrete. Cable must be protected at all locations such as unimproved roads, streets and alleys that may later be paved or asphalted. CAUTION:

Depths less than those specified may expose the cable to erosion or excavation damage

In conditions where these depths are not feasible or permitted lesser depth is

permissible provided additional protection in the form of concrete casements or sub duct is provided.

8.2 Splice Points Splice point locations must be chosen carefully to have easy access for future maintenance. Splicing must always be done in the car and in order to reach splicing vehicle, ensure a minimum of 10 ~ 15meters of extra cable on both cable ends at each splice point.

At Hand Holes and Man Holes place the cable slack vertically (in line with the cable route)

In the case of a buried splice point, coil and bury the slack horizontally as shown in the Figure below

Figure 9: Arrangement for splicing at site

20 Cm

Warning Tape

10~15M slack

Splice Pit 2 x 2 Meter

80~120 cm

Splicing Van


Figure 10: Arrangement of splice enclosures

Figure 11: Arrangement of Buried Splice

Buried Splice Point Man Hole Hand Hole

Buried Joint Top View

20 cm 20cm

Soft Sand

Soft Sand

20 ~70 cm

80 ~130 Cm

Min 2Meter

Back filling

Front View

Warning Tape

20cm Tiles

Direct Buried Splice


9. Points To Remember

9.1 Safety First! Small scraps of glass i.e. cleaved-off ends of the fibres being terminated or spliced is very dangerous! They are extremely sharp and are basically glass needles that will easily penetrate flesh then break off and become nearly impossible to remove. Once in the body it will likely become infected. If they get into the eyes, they are very hard to flush out. Don't even think about what happens if you eat one. Always follow these rules when working with fibre.

Find and dispose-off all cut fibre fragments immediately after cutting.

Dispose-off all scraps properly

Handle cut fibre fragments with tweezers only

Do not drop them on the floor where they will stick in carpets or shoes and be carried elsewhere.

It is your responsibility to ensure that no fibre fragments ‘escape’ and injure someone. If you lose a fibre fragment you must look until you find it.

Fibre fragments can stick to the cover of the cleaver. Move slowly when opening the cover. Always look on the inside of the cover if you don’t see your fragment on the shelf of the cleaver.

If you can’t find your fragment, get more light on the subject and work area.

Do not move the cleaver until the fragment has been found.

Use a magnifying glass if you need to but FIND THAT FRAGMENT.

Do not eat or drink anywhere near the work area.

The light in Transmission system is infrared and you can't see it therefore always be careful with your eyes.

When using a fibre optic microscope. NEVER look into a fibre unless you personally confirm no light is present. Use a power meter to check it.

9.2 Zero Tolerance for Dirt With fibre optics, our tolerance to dirt is near zero. Airborne particles are about the size of the core of SM fibre- they absorb lots of light and may scratch connectors if not removed! Dirt on connectors is the biggest cause of scratches on polished connectors and high loss measurements!

Try to work in a clean area.


Always keep dust caps on connectors & patch panels when not in use. Keep them covered to keep them clean.

Use lint free pads and isopropyl alcohol to clean the connectors.

After cleaning with isopropyl alcohol swab do not forget to clean it with the Cleaning Tape

9.3 Tools and Materials

Make sure to have the proper tools for the job.

Confirm that all tools are in good shape before you head out for the job. This includes all the cable tools and test equipment.

Make sure that your test cables are good? Without that, good terminations are tested as bad every time.

Make sure that your test equipment is fully charged and you have spare battery backup.

9.4 Documentation and Record Maintenance It is very hard to troubleshoot cables when you don't know how long they are, where is the route or how they were tested originally! So keep good records. It is recommended that the following records be maintained and kept current always:

Schematic drawings – to include "as-built" information for street maps records

Splice loss data

End-to-end optical loss measurements

End-to-end OTDR traces


10. Check List and Procedures for Final Repair / Relocation of Fibre Optic Cable

10.1 Civil works & Preparation in the field 1. Opening of TC with TNOC for the excavation on the existing cable.

2. Execution of Civil works. (Under supervision of MC cable technicians)

3. Laying/Pulling of By Pass/New Cable

4. Installation of enclosures and testing of New/Bypass cable. (Secure new splice

enclosures with plastic foil (bag) to avoid water or sand intake)

5. Marking of cutting point for existing cable, keeping in mind the maintenance

loop of 15 meter each side.

6. Assure site accessibility and secure work site with safety signs. (i.e. traffic signs,

road cones, warning tape)

7. OTDR testing of Dark Fibre Measurement prior to MDT

10.2 Organizing MDT/TC 1. Fibre utilization Form must be filled correctly for both sites of the section

involved

2. All working and spare fibres at both sites (ODF’s) must be clearly identified

and labelled.

3. Splicing Machines and Test Equipment must be checked prior to MDT.

4. MC Supervisor is responsible to arrange a meeting with all scheduled staff, to

determine tasks and procedures to be followed during MDT

5. MDT request


10.3 List of tool & Test equipment Item in red are mandatory for emergency and final splicing (Item 1 to 13 in the list) 1. Fibre Phone sets (2X2)

2. Satellite Phone

3. OTDR

4. Cable locator (fault locating only)

5. Testing Patch Cords

6. Power Meter (Max Tester)

7. Laptop (for SDH Technician)

8. Mobile Generators

9. Emergency Lights for night work.

10. Floppy Disk for recording of OTDR test results.

11. Power extension cords

12. Mechanical Splices (to connect fibre phones)

13. Fibre Optic Cleaning and Preparation Tools (Please refer to toolkit details on

page 12)

14. Splicing Machines

15. Enclosures (already preinstalled during site / cable preparation)

16. Splice protection (Heat shrink) sleeves

17. Hot air gun

18. Splicing Cars

10.4 Staff Arrangements 1. Each cable splicing team will comprise of two-cable technicians and two

labourers.

2. Two teams will work simultaneously at both splicing points.

3. For coordination and disconnection/reconnection of Fibres at ODF, SDH

technician must be available at both terminal sites of the section involved.

4. At least at one terminal site SDH technician must have Laptop for local login and testing in case of any problem /outage or loss of association at TNOC.


10.5 Execution OF TC/MDT 1. MDT / TC approval from TNOC.

2. Contact and inform to TNOC regarding TC/MDT 15 minutes prior to start of

MDT/TC.

3. Contact TNOC at start time of MDT and get OK/ Go Ahead from TNOC.

4. Keep TNOC on line; disconnect working fibres from ODF one by one at one site

only.

5. Reconfirmation from TNOC regarding stability of systems.

6. In case of any unexpected outage reconnect fibre in coordination with TNOC and

ask for TNOC’s advice as well as inform to Senior Engineer LDN HQ according

to escalation procedure.

7. If all systems are stable according to TNOC’s information, disconnect working

fibres from ODF of second site of section involved.

8. Cut cable and start preparation of cable ends.

9. Installation of fibre phone and testing with SDH technician on terminal site.

10. Splicing of fibres according to the priority (Most important system first)

11. Testing & recording of results for fibres immediately after splicing and before

reconnecting the systems. (Max Tester and OTDR testing)

12. Reconnection of fibres one by one at ODF of both terminal sites immediately after splicing and testing. (Do Not Forget to clean pigtails/connectors according to the cleaning procedure before reconnection at ODF)

13. Reconfirmation with TNOC if the systems are restored to normal.

14. In case of any problem retesting of the fibre and reconnection according to

TNOC’s advice and Fibre Utilization Plan.

15. After completion of splicing for all fibres, reconfirmation from TNOC regarding

stability of all working systems.

16. Fibres must be organized carefully in splice enclosure to avoid Macro-Bends.

17. Closing of splice enclosures and securing the cable with splice enclosure with heat

shrink sleeve.

18. Inform TNOC when splice enclosures are closed permanently.

19. Preparation of cable maintenance loop and storage of splice enclosure.

20. In case of direct buried cable, backfill 30cm with soft sand and place tiles above

the splice.


21. In case of Manholes, secue the splice on the brackets in the Manhole.

22. Installation of Marker Posts.

23. Update the drawing and submit updated drawing and test results to LDN HQ.

10.6 Test Required 1. OTDR testing from both terminal sites of the section involved immediately after

splicing.

2. Section loss test with MaxTester (Optical Loss Test Set) immediately after splicing.

10.7 Priority of Systems Priority of system changes according to the situation. Unprotected systems are always

on Top Priority. Under normal circumstances following sequence of System Priority

must be followed.

1. Unprotected System

2. DWDM Systems

3. High Capacity SDH Systems

4. Line Sections


10.8 Emergency Repair Process 1. At all times satellite phone must be dispatched with cable team in order to avoid

communication problem during restoration activities in the areas without GSM coverage.

2. During the process of mechanical splicing, SDH technicians must be available at

both sites of the section involved. 3. Care must be taken in opening and closing of ODF trays to avoid damage or

macro-bending of pigtails and patch cords. 4. SDH technician must have power meter at one site and OTDR on the other site in

order to perform continuity test. 5. After mechanical splicing of each fibre, OTDR test must be performed to check

the quality of the mechanical splice. 6. Prior to connect fibres with the system, test with laser source and power meter

must be conducted in order to ensure the correct sequence and continuity of fibres at both sites.

7. After above-mentioned tests, fibres must be connected to the system. 8. If the system is not restored, troubleshooting must be done according to the

following steps.

a) First of all direction of failure must be identified.

b) Faulty fibre No must be identified. c) OTDR test must be performed to check the quality of mechanical

splice. d) If the quality of mechanical splice is good and trace shows continuity

through mechanical splice point then continuity test with laser source and power meter must be performed in order to confirm the continuity of fibre and correct sequence at ODF’s of both sites.

e) Both ODF’s must be checked carefully for micro-bending of ODF

pigtails or patch cords.


11. Guidelines for opening and updating of Threatening Trouble Tickets.

_____________________________________________________________________ This document explains the procedure to track the movement of third parties along the cable route during the course of activity. This includes the third parties and Detasad OP group working for relocations of cable.

11.1 Updates related to monitoring of activities by Third Parties on or near to the cable:

1. Cable Patrol technicians must issue a verbal warning to the third parties

working within a distance to 10-50 meters from the cable route in order to make them aware about presence of cable in the vicinity.

2. They must be given the contact number of MC Supervisor with advice to

contact MC supervisor in case they want to work on near to the cable.

3. A written warning letter must be issued to the companies working on or near to the cable (i.e. within 10 meters) of the cable route. Cable patrol must advise them to contact MC for physical location of the cable within their area of work.

4. Third parties found working within 5meters of the cable route must be advised

to stop the work immediately and contact MC supervisor for the process of physical cable location to avoid cable damages.

5. In such cases cable patrol must immediately inform MC Supervisor regarding

name of the third party, their contact person name and contact number as well as exact location of their work.

6. SV MC must send the cable technician to assess the situation and to get more

information for further action.

7. Once the warning letter is issued physical location of the cable must be carried out by the cable technician and a request for opening a threatening trouble ticket must be send to LDN HQ.

8. The warning letter is valid for a maximum of three months time and if the

work of the third party is not completed within three months new warning letter must be issued and trouble ticket must be updated accordingly.

9. Physical cable location is also valid for a maximum period of three months

and it must be redone if the work of third party is not completed within three months.


Once the trouble ticket is opened and referred to the MC, MC must regularly update the trouble ticket regarding on going activities of the third party until the work of third party is completed. Following guidelines for updating the threatening trouble ticket must be followed. 1. First update must include the following:

1.1. Name of third party

1.2. Contact Number of third party

1.3. Nature of work

1.4. Date of warning letter

1.5. Date of physical cable location

1.6. Exact location of third parties work with reference to land marks and

kilometers readings from the FON sites.

a. Distance from Site-A

b. Distance from Site-B

c. Length of working area

d. Between Marker Post No. XXX & Marker Post No. YYY

e. XXX-meters from MP-XXX and YYY-meters from MP-YYY

(Please see Fig-12 below for reference)

Figure 12: Information for 1st update of Threatening Trouble Ticket

Site A Site B

Working area of third Party

KM from site A KM from site B

Marker Post No.XXX Marker Post No. YYY

Length of working area on or along the cable route.

Distance from nearest Marker Post XXX

Distance from nearest Marker Post YYY


2. Cable technician / Cable Patrol Technician must visit the sites of third parties work regularly (at least every alternate day / every day for critical sites) and progress of wok must be reflected in the threatening trouble ticket clearly with reference land marks and kilometers readings. Remarks usually seen in the trouble ticket “work in progress” is not enough.

3. All updates following the first update must reflect the progress of third party work

with reference to the start location. Always nearest Marker Post Numbers on left and right side of the working area must be mentioned as reference.

Examples:

i. Company started work at xxx-meters from MP-xxx. The working area is aaa-meters/Km wide along the cable route. (Refer Fig-13 Below).

Figure 13: Working Area of Third Party

Site A Site B

Working area of third Party

KM from site A KM from site B

Marker Post No. YYY

Length of working area on or along the cable route.

Distance from nearest Marker Post XXX Distance from

nearest Marker Post YYY Marker Post No.XXX

Total working area of third party Current working area of third party

Working area of third party where work completed but not yet completely backfilled

Working area of third party where work completed and area completely backfilled

LEGEND:

1st reference: - Distance from MP-XXX Direction Site-A

2nd reference:- Distance from MP-YYY Direction site-B


ii. Company has completed work at xxx-meters from MP-xxx. The area is backfilled / not yet backfilled and currently they are working xxx-meters from nearest MP-xxx direction site-A & YYY-meters from nearest MP-YYY direction site-B. The working area is aaa-meters/Km wide along the cable route. (Refer Fig-14&15 below). These updates with references must be done continuously until the work of the third party is completed in the section.

Figure 14: Information for Trouble Ticket update during course of activity

Figure 15: Information for Trouble Ticket update during course of activity

4. Updating of trouble ticket must also include the statement regarding status of

Marker Posts if these are damaged, broken, removed or missing during the activity of third party. Affected Marker Post must be clearly identified in the update with Marker Post No. and section (i.e. Site A and Site B).

1st Reference for current working area of third party (i.e. XXX-meters from MP-XXX direction Site-A)

Reference for completely backfilled area

(i.e. xxx-meters from nearest MPxxx)

2nd Reference for current working area of third party (i.e. YYY-Meters from MP-YYY direction site-B)

Reference for completely backfilled area

Reference for working area of third party where work is completed but area not

yet completely backfilled

2nd Reference for current working area of third party

1st Reference for current working area of third party


5. If the damage to Marker Post during the activity is observed warning letter regarding damage to marker Post must be issued to the third party and an update regarding issuance of warning letter must be included in the update of the ticket with date, time, Name of person to whom the warning letter is issued and contact number.

6. Once the work of the third party is completed. Ticket must be updated with

closing remarks which must include the complete status of cable route within the working area of third party. For example not backfilled properly, debris and construction material not removed from the cable route, No of missing, broken, tilted or removed Marker Posts etc. (Please see Fig-16: below for reference)

Figure 16: Information for Final update of Threatening Trouble Ticket

11.2 Updates related to relocation activities by third parties: LDN cable is under our O&M responsibility and Relocation work done by third parties as well as Detasad OP group on this cable is required to be monitored in order to ensure that the work is executed according to the STC specifications. Deficiencies if any are required to be identified and must be escalated to STC Transmission Operation Riyadh immediately after the completion of work. If these deficiencies are not reported to STC TO well in time, Detasad has to clear as well as bear the cost to clear these deficiencies. In order to avoid this, relocation work on LDN cable must be closely monitored in addition to above mentioned guidelines. In this regard a study was made and a Hand Over / Take Over Procedure was developed and submitted to STC Transmission Operation Riyadh. The objective of this process was to formally Handover the cable section to third party working for the relocation and to takeover after the process of relocation is completed. Once implemented, this process will help to control the activities of third parties working for relocation of cables under our maintenance responsibility. This process is yet with STC Transmission Operation

Broken

Down Tilted Missing

Area not backfilled properly

Debris & Construction Material on the cable route left by third party


Riyadh under study for implementation. Until this process is implemented under mentioned guidelines must be followed to control the activities of these third parties in order to avoid penalty discussion due to deficiencies as a result of these projects. Under mentioned are the important points to be recorded in this regard.

1. During routine cable route patrolling cable technician must observe the following during the process of cable relocation.

• If the depth of trench is according to specification. • If cable is laid on the soft sand bed (i.e. 20 cm)

• If cable is covered with soft sand (i.e. 20cm)

• If the warning tape is laid.

• Length of newly laid cable (i.e. Km reading at both ends of

new cable.

2. During MDT following observations must be made.

• If both sites were manned by third party. • Fibers at ODF of both sites were disconnected by the third

party in coordination with TNOC prior to start MDT.

• OTDR and Section Loss measurements were carried out for working fibers prior to reconnection at ODF.

• OTDR and Section loss measurements were carried out for dark

fibres.

3. One day after the execution of MDT by the third party MC technician must perform and record OTDR and Section Loss measurements for the relocated section in order to verify the quality of work done by the third party.

4. In addition survey of the cable relocation area must be carried out to

confirm that the newly relocated area is backfilled properly and Marker Posts from the old route are being removed and Marker Posts at the newly relocated route are installed by the third party according to STC specification.

All deficiencies found must be recorded and pictures must be taken for the deficiencies if any and complete report of these deficiencies observed during the whole process together with the OTDR and Section Loss measurements must be sent to LDN HQ within three days of the completion of MDT for further escalation to STC Transmission Operation Riyadh.


11.3 Updates related to MDT’s executed by third parties for Relocation Projects.

After execution of MDT / TC by third parties for relocation of cable, MC concerned must update the ticket correctly. At present these tickets always have only one Remark (MDT Completed Successfully). This remark is not enough and does not reflect the real picture of the scenario. There were several instances when the systems were not restored after the MDT executed by third party and our manpower was extensively involved to troubleshoot and restore the traffic. Several times transmission equipment was damaged due to mishandling by third party as well as due to their ignorant attitude towards guidelines related to execution of MDT/TC issued by STC TO. Due the missing information in the ticket the damage caused by third parties could not be reported to STC Transmission Operation. Following guidelines must be followed therefore to update the Trouble Ticket after completion of MDT by third party.

Trouble ticket must include clear remarks if third party ignored the guidelines, such as:

• Both terminal sites were not manned by the third party. • Fibers at ODF of both sites were not disconnected by the third party in

coordination with TNOC prior to start MDT.

• Cable was cut without any coordination with TNOC.

• OTDR and Section Loss measurements were not carried out for working fibers prior to reconnection at ODF.

• Damage / failure of any equipment due to mishandling and non

compliance of guidelines for execution of MDT.

• Delay in restoration of systems due to the activities of third party. Supervisor of the MC is prime in this regard, he must make sure that trouble ticket is properly updated according to these guidelines reflecting all events during the MDT.


12. Cable Route Marker Posts

12.1 Types of Cable Route Markers Posts

Figure 17: Types of Cable Route Marker Posts

12.2 Installation of Cable Route Markers Posts

Diagram below illustrate the guidelines for Marker Post installation.

Figure 18: Marker Post Placement

Site A Site B

Standard Distance250 meters

Site A Site B Diversion

Site A Site B

Protection Splice Point

Site A Site B Relocated Area

Normal Cable Route Marker

Cable Route Marker for Protection

Cable Route Marker for Diversion

Cable Route Marker for Splice Location


13. Relocation Options

Figure 19: Relocation Option-1

Figure 20: Relocation Option-2

All MC’s must strictly follow these guidelines. Region must ensure the implementation through the under mentioned process.

1. Cable patrol Technician / Cable Technician must submit Daily Cable Route

Patrolling Report Form to the Supervisors with details of third parties working on the cable as well as Marker Post status (i.e. tilted, broken, down and missing).


2. Supervisor of the MC must ensure that these reports are reviewed on weekly basis

and a weekly status report is prepared. 3. Based on the weekly status report corrective action must be carried out on weekly

basis for the Marker Posts not related to Third party activities. 4. Warning letter to the third party must be issued regarding damage of marker posts. 5. A monthly status report must be sent to LDN HQ.


14. Guidelines for 3rd Party MDT/TC’s executed on existing Fiber Optic Cables

1) MDT/TC Implementer (3rd Party) shall contact TNOC & NNCC at least 15

minutes prior to approve start time to notify that they are ready to implement the MDT/TC activities as requested.

2) Confirm with TNOC for the go ahead during the approved start time.

3) MDT/TC Implementer (3rd Party) should keep TNOC on line as they

disconnect the fibers at ODF one by one on site A.

4) Ensure that the system is stable. In case of outage re-connect the fiber in coordination with TNOC and wait for their advice.

5) Once confirmed by TNOC that the systems are stable, MDT/TC Implementer

(3rd Party) shall disconnect the fibers at ODF one by one on site B of the section involved - in close coordination (online) with T-NOC.

6) After confirmation by TNOC, that there is no outage and the system is stable,

the MDT/TC Implementer (3rd Party) can start work on Fiber Optic Cable.

7) MDT/TC Implementer (3rd Party) should splice the fibers according to priority.

8) After splicing, MDT/TC Implementer (3rd Party) shall conduct OTDR and

section loss test of the working fibers.

9) MDT/TC Implementer (3rd Party) shall reconnect the fibers one by one to its original allocation on site A&B in close coordination (online) with T-NOC. Pigtails/connectors must be cleaned (with cleaning cassette) before reconnection at ODF. Reconfirm with TNOC if system is stable & working as per the original allocation.

10) MDT/TC Implementer (3rd Party) should confirm from TNOC that all alarms

are clear on the route.

11) Once TNOC confirmed that there is no outage and/or alarm(s) on the route, and MDT/TC Implementer (3rd Party) confirms that all the activities are completed, TC / MDT can be declared as finished.

Exception: Fibers on ODF should not be disconnected if the job is related to open an existing splice and connect spare fibres to new cable.

Field Maintenance (DETASAD) must be on site to observe the disconnection of fibers one by one at the ODF of site A & B by the MDT/TC Implementer (3rd Party).


15. Physical Cable Location

15.1 Introduction Cable location is one of the most important aspects of the cable maintenance. It relates to a technique for locating a buried cable, by comparing the radiation pattern of a locating signal induced on the cable to an expected radiation pattern for such a signal. Given that burial records may not always yield an accurate indication of the location of an underground cable, we must physically locate cables in order to provide warnings to excavating contractors. In practice, a technician physically locates a buried cable using a cable locator and cable locating works well when no other buried utilities are present in the area. However, other buried utilities are often present in the same area as the cable and each such utility will radiate the electromagnetic signal induced in the target line (i.e. Cable). Consequently, a technician trying to locate a particular cable will some times detect the signals at different locations, rather than the same location above the buried cable. This may lead to wrong results. Therefore locating buried cables is a responsible business. Accurate and precise information is required to be provided to third parties as well as to maintenance teams. Wrong or incomplete information can mislead the third party causing damage to cable during their activity as well as this could mislead the teams during troubleshooting to find the exact location of damage.

15.2 Basic Theory. A Cable locator does not locate buried cables! It detects a magnetic field around the cable created by an alternating current (AC) flowing along the cable sheath. This magnetic field forms a cylindrical shape around the cable and is known as the signal. Alternating current creates the detectable magnetic field or signal because it is not only field but also an oscillating frequency which makes the location possible. Cable locator generally consist of two parts 1. A transmitter 2. A receiver

The transmitter puts an electrical signal onto the cable or pipe being traced, while the receiver picks up that signal, allowing the locator operator to trace the signal’s path and follow the cable being located. The electromagnetic field created by the transmitter can usually be set to a specific frequency. Frequency choices can range from less than 1 kilohertz to about 480 kHz. With this range of frequencies, it is important to keep one thing in mind Always start out at the lowest frequency, and if that frequency works, don’t change it. The reason is that lower frequencies seem to stay on the target line (i.e. cable under location) and does not induce to the adjacent lines.


15.3 Applying the Signal

There are three methods of applying signal with a transmitter:

1. Conductive / Direct Connection method

2. Inductive method

3. Inductive Clamp method With any method of applying signal, frequency choice is important to get the "most" signal on the cable. Any signal applied to an insulated, buried cable leaks off to ground; as it gets farther away from the transmitter, the signal gets weaker and finally disappears. How fast it leaks off is determined by:

1. Cable diameter.

2. Wet or dry soil conditions.

3. Signal frequency. Since we do not have any control over the first two conditions, the Transmitter offers more than one frequency choice:

1. Low (<1 kHz): These frequencies usually provide the most accurate locate in congested areas (the lower the frequency, the better). They are best for tracing over long distances and do not couple easily to other buried conductors. These frequencies are too low to be used with Inductive clamp or inductive methods and so the conductive method should be used with these frequencies.

2. Medium (1 kHz - 30 kHz): Medium frequencies are the most useful general-

purpose signals. They allow the use of the Inductive clamp method. Although they will couple to other nearby cables, medium frequencies do not do so as strongly as high frequency. Medium frequencies travel less far than low frequencies but farther than the high frequencies. They are best when the Inductive clamp method is used (when the conductive method cannot be used) and the tracing distance is one mile or less. These frequencies may not be high enough to induce a strong signal on small diameter lines like telecom cables.

3. High (30 kHz - 100 kHz): High frequencies attenuate over shorter distances

than low or medium frequencies. They travel well on small diameter conductors (CATV and Telecom). High frequencies will couple strongly to other nearby conductors. They work best with inductive clamp and induction methods. If the receive signal is weak at the beginning of the trace, try a higher frequency.


4. Very High (100 kHz and higher): These frequencies attenuate rapidly with distance and so are intended for shorter runs. They couple strongly to other nearby conductors and will couple across non-conductive gaps such as cable breaks. They work best with Inductive clamp and induction methods. Very high frequencies are best for sweeping a large area to locate all buried cables and pipes.

The three most common methods of sending signals are direct connect, general induction, and inductive coupling. In the inductive coupling method, the cable must be grounded to form a complete circuit path.

15.3.1 Conductive / Direct Connection method

Connecting a signal directly to the cable is the most accurate method of cable locating. The direct-connect method allows to physically attach transmitter to the cable to be located by gaining access to the shield that surrounds the cable. That means to connect it at a terminal site or cabinet by gaining access to the cable shield which is usually grounded at this point. Disconnect the shield from frame or rack ground point and connect one end of the transmitter to the shield and other end to the ground bar so that the transmitter is connected in series between the cable shield and ground bar. Do not disconnect the far-end shield from ground bar since this supplies a far end ground. When tracing a cable over a long distance, the signal strength decreases gradually as the receiver moves along the cable. Missing splice point ground connection causes an abrupt or distinct drop in signal. Therefore missing ground connection at splice points ground connection can severely limit the tracing distance.

Figure 21: Cable Locator Direction Connection


15.3.2 Inductive method If it is impossible to directly attach the transmitter to the cable, then the induction method may be the logical choice. Here, the transmitter is placed on the ground directly over the cable with transmitter arrow parallel to the cable to be located. This is the simplest way to put signal on a buried cable. However, you have to have some idea where the conductor is buried. When the Transmitter is turned on, a signal current is induced into any parallel conductor within range. It is therefore important to place the unit directly over the target cable. The effectiveness of this method decreases rapidly if you place the Transmitter even 5 or 10 feet to either side of the path. In congested situations where other services such as gas or water pipes, Electrical cables are all buried nearby, it is not advisable to use the inductive method because the signal will be applied to all nearby conductors causing confusion during the trace. The strength of the induced signal depends on three things:

• The Transmitter frequency, • How well the conductor is grounded, • How deep the conductor is buried.

When using the inductive method, the high frequencies (82 kHz or 455 kHz) should be used. Both of these frequencies will couple to the nearest conductors. Keep in mind that 455 kHz will definitely put signal on conductors other than the one you are tracing. The Receiver can pick up signals from the Transmitter through the air from 40 feet away, even if no cable exists in between. The cable must be well grounded at both ends to produce a good locate. In all methods, the better the ground to the conductor, the stronger the signal.

Figure 22: Cable Locator Inductive Method


15.3.3 Inductive Clamp method Another way to put signal on a cable is the Inductive clamp method. Although inductive coupling doesn’t let the user directly connect to the cable, it provides a higher level of confidence than does general induction. The Inductive clamp puts signal selectively on a cable by clamping around it. This eliminates the need to disconnect the cable. The Inductive clamp puts signal on a cable between grounds, so where you place it is important. Insert the plug into the transmitter jack BEFORE TURNING THE POWER ON, open the jaws of the clamp and place it so that it completely encircles the desired cable. Make sure the clamp can fully closed.

Figure 23: Cable Locator Inductive Clamp Method

15.4 Tracing of Cable To get the most accurate results when tracing a cable, signal should be isolated to the individual cable. This means using either the Conductive or the Inductive clamp methods of applying signal. If access to cable is not possible, then use the induction method. Trace the cable at a slow walk while moving the Receiver in a side-to-side motion. Periodically mark the path. As tracing proceeds, remember that the most powerful signal is near the Transmitter. As the Receiver gets farther away from the Transmitter the signal strength drops off. It will be necessary to readjust the gain periodically to be sure there is adequate signal for the Receiver to operate. There are two modes for detection. One is called Peak mode and the other is called Null Mode. In Peak Mode the Receiver will exhibit a peak response at the top of target cable. The pitch of the sound from the Receiver's speaker increases to a


maximum as the receiver crosses the cable. It diminishes as the receiver moves away from the cable path. The numeric strength indicator also increases to a maximum. Consequently in Null mode the receiver will diminish at the top of the cable. It will exhibit increased response as it moves away from the cable path. On the display of the receiver arrows are indicating the cable path as described below.

Right Arrow: Move Receiver to the right to get closer to cable path.

Left Arrow: Move Receiver to the left to get closer to cable path.

Both Arrows and Bar: Receiver is directly over the target. This is also accompanied by a beeping sound.

When all three arrow elements are OFF, the signal strength is not adequate to make a directional determination. Keep searching based on the signal strength indication (you may need to increase the gain) and the audio feedback, until one of the arrows comes ON.

15.5 Adjusting the Gain The Receiver gain setting determines the sensitivity to a signal. It is an important adjustment. Too little gain and the signal may be lost - too much gain and accuracy is lost or worse the wrong conductor is traced. The receiver has the ability to operate in manual or automatic gain control modes (AGC). Always adjust the Receiver gain only when you are over the target cable. As you trace cables away from the transmitter, the signal becomes weaker and it may be necessary to manually adjust the gain. Always operate at the minimum gain that shows a clear "peak" over the target. It is not important what the signal strength number is at the peak, as long as it clearly decreases on each side of the target. It is NOT necessary to operate with a signal strength close to 100%, the signal is saturating the amplifiers and the gain should be reduced. For best results keep between 20 and 80. It is recommended to always start from 50% gain selection.


16. Colour scheme

Colour Fibre No.

BLUE 1 ORANGE 2 GREEN 3 BROWN 4 SLATE 5 WHITE 6 RED 7 BLACK 8 YELLOW 9 PURPLE 10 ROSE 11 AQUA 12

cable handbook revised

Documents

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definition of fibre

fibre optic cable maintenance

testing of fibre optic

fibre optic tool kit

types of fibre optic

optical fibre splicing

fibre loss variables