Advanced Cable Fault Locating - Oct 11-06

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TELUS REV 2006-10-11


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ADVANCED CABLE FAULT LOCATING Student Handbook

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TELUS Learning Services

Burnaby Calgary Edmonton

5th Floor, 3777 KingswayBurnaby, BCCanada V5H 3Z7Tel: 604-432-3455Fax: 604-298-1387

2nd Floor, 120-7th AvenueCalgary, ABCanada T2P 0W4Tel: 808-248-5327Fax: 403-530-7525

5W 10035 – 102 AvenueEdmonton, ABCanada T5J 0E5Tel: 808-248-5327Fax: 780-493-2634

Copyright 2006 by TELUS Communications.

All rights reserved. No part of this publication may bereproduced in any form, by any photographic, electronic,mechanical, or other means, or used in any informationstorage and retrieval system, without written permission ofTELUS Communications.

Printed in Canada


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Student Handbook ADVANCED CABLE FAULT LOCATING

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Table of Contents


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Table of Contents

ADVANCED CABLE FAULT LOCATING............................................................9 INTRODUCTION...............................................................................................9

BASIC THEORY FOR TESTING........................................................................13 INTRODUCTION.............................................................................................13 PRIMARY CABLE ...........................................................................................15 CHARACTERISTICS ......................................................................................15

Series Resistance........................................................................................15 Shunt Capacitance ......................................................................................17 Series Inductance ........................................................................................17 Shunt Conductance .....................................................................................17

TRANSMISSION CHARACTERISTICS ..........................................................19 Attenuation...................................................................................................19 Characteristic Impedance............................................................................19

Impedance Mismatch ...............................................................................20 CABLE, NON-LOADED...................................................................................21

Net Loss ......................................................................................................21 Slope ...........................................................................................................23 Impedance...................................................................................................23 Return Loss .................................................................................................25

SUMMARY......................................................................................................29 NOISE THEORY & MITIGATION DEVICES ......................................................33

INTRODUCTION.............................................................................................33 NOISE .............................................................................................................35

Definition......................................................................................................35 Noise Origins ...............................................................................................35 Noise Limits .................................................................................................35 Classification and Sources of Noise ............................................................36

DC Noises ................................................................................................36 AC Noises ................................................................................................37

CONDITIONS FOR POWER INDUCTION......................................................39 Influence ......................................................................................................39 Susceptibility................................................................................................41 Coupling ......................................................................................................43

DESIGN TECHNIQUES TO MINIMIZE NOISE...............................................45 EXTERNAL NOISE MITIGATION DEVICES...................................................49 Noise Chokes or Longitudinal Chokes.........................................................49

Neutralizing Transformer .............................................................................51 Harmonic Suppression Reactor...................................................................55 Smart Switch................................................................................................55 Solid State Protectors ..................................................................................57


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VOICE FREQUENCY BROADBAND TESTING & MEASUREMENTS USINGDYNATEL 965DSP/SA.......................................................................................61

INTRODUCTION.............................................................................................61 ACCEPTED MEASUREMENTS......................................................................63 FOR POTS SERVICE AND BROADBAND .....................................................63 Acceptance Measurements for POTS Service.............................................63

Accepted Measurements for Broadband .....................................................65 DYNATEL 965DSP/SA TEST FUNCTIONS....................................................67

DSL Function ...............................................................................................69 DSL Test Menu ........................................................................................71 ISDN Error Test........................................................................................73 DSL Loss..................................................................................................75 DSL Noise ................................................................................................75 Spectrum Analyzer ...................................................................................77

TDR .............................................................................................................81 TDR Setup ...............................................................................................81 TDR Controls ...........................................................................................83 TDR Modes ..............................................................................................89 TDR Save.................................................................................................97 Event Recognition ....................................................................................99 TDR Trace of a Good Pair......................................................................101 TDR Rules..............................................................................................103 TDR Rules Summary .............................................................................106 Masking..................................................................................................109 TDR Trace Samples...............................................................................111 TDR Controls .........................................................................................117 Maximum TDR Range............................................................................119

dB ..............................................................................................................121

Loss .......................................................................................................123 Noise......................................................................................................123 Longitudinal Balance ..............................................................................125 Wideband (Broadband) Loss..................................................................127 Level Trace ............................................................................................129

Auto Test ...................................................................................................131 Auto Test without Fed ............................................................................135 Inactive Pair – without Fed.....................................................................135 Inactive Pair Test Results.......................................................................139

Active Pair (No Fed)...............................................................................141

LINE QUALIFICATION TESTING WITH FAR END DEVICE (FED II) AND THE965DSP/SA ...................................................................................................157 TESTING PAIRS WITH FED II ......................................................................161

Auto Test with Fed.....................................................................................161 FED II Connections....................................................................................161 Inactive Auto Test with FED II....................................................................163


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WIDEBAND (BROADBAND) TEST WITH FED II..........................................169 Wideband Loss Test Frequencies .............................................................173 Error Screens.............................................................................................175 Wideband/Broadband Auto Test Results...................................................177

Auto Test Configuration .............................................................................181 Fed II Special Applications ........................................................................185

Auto Test Save ..........................................................................................193 TALK SET .....................................................................................................197

Talk Set Setup ...........................................................................................201 SUMMARY....................................................................................................202 DYNATEL 965AMS ADSL2+ SERVICE MODULE........................................203

Module Installation.....................................................................................203 Hook-Up ....................................................................................................205 Initial Set-Up ..............................................................................................205 Basic Operation Details .............................................................................210

Advanced Operation ..................................................................................215 WAN Set-Up ..............................................................................................215 WAN Set-Up Transport Type.....................................................................215 WAN Set-UP - Address Mode....................................................................219 LAN Set-UP ...............................................................................................221 PING..........................................................................................................223 PING Set-Up..............................................................................................223 PING Hook-Up...........................................................................................226 PING Operation .........................................................................................226 Thru Mode .................................................................................................228 Thru Mode Hook-Up ..................................................................................228 Thru Mode Operation.................................................................................229

ADSL MODEM TESTING AND PC LINK.........................................................233 INTRODUCTION...........................................................................................233

ADSL MODEM TESTING..............................................................................235 965 DSP ADSL Modem .............................................................................237 Testing.......................................................................................................237

ADSL Setup...............................................................................................239 Threshold Setup ........................................................................................239

ADSL Self Test ..........................................................................................241 Establishing Connection ............................................................................241 First Test Screen .......................................................................................243

ADSL Status ..............................................................................................243

ADSL Information Screen ..........................................................................247 OSI 7- Layer Model....................................................................................249

ADSL Alarms .............................................................................................251 ADSL Graph ..............................................................................................253 ADSL Warning Screens.............................................................................255


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PC LINK ........................................................................................................263 Installing PC Link .......................................................................................265 Loading Test Results .................................................................................269 Exporting To an Excel Spreadsheet ..........................................................275 Importing to Excel ......................................................................................279 Renaming the Sheets ................................................................................283 Loading ADSL Modem Test Results..........................................................285 Viewing ADSL Results with PC Link..........................................................289 Export One or All ADSL Results to Excel ..................................................295


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ADVANCED CABLEFAULT LOCATING

BASIC THEORY

FOR TESTING

NOISE THEORY AND

MITIGATION DEVICES

VOICE FREQUENCY BROADBANDTESTING & MEASUREMENTS USING

DYNATEL 965DSP/SA

ADSL MODEM TESTING & PC LINK


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ADVANCED CABLE FAULT LOCATING

INTRODUCTION Welcome to the Advanced Cable Fault LocationCourse. Prior to this course you should have takenthe Cable Fault Locate Course.

The course is 3 days in length and contains thefollowing units:

Unit 1 - Basic Theory For Testing

Unit 2 - Noise Theory & Mitigation Devices

Unit 3 – Voice Frequency Broadband Testing andMeasurements using Dynatel 965DSPKA

Unit 4 – ADSL Modem Testing and PC Link.


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UNIT 1

Basic Theory

For Testing


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BASIC THEORY FOR TESTING

INTRODUCTION In this unit we will review the basic theory requiredto perform advanced fault locating on voicefrequency cable pairs.

Topics are:

• Primary Cable Characteristics• Transmission Characteristics• Cable, Unloaded.


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Electrical Characteristics of aCable pair

Loop Resistance – Ohms/Km


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PRIMARY CABLECHARACTERISTICS

There are four electrical characteristics of a cablepair:

• Series Resistance• Shunt Capacitance• Series Inductance• Shut Conductance.

Series Resistance Is the resistance of the cable pair or conductor.

It depends directly upon the gauge and temperature

of the cable pair.

Measurements of resistance are expressed inOhms (Ω) per kilometer.

The table indicates how the resistance increases(Ohms/Km) as the temperature rises and gaugeschange.


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Cable Pair Shunt Capacity

Cable Pair Shunt Capacitance


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Shunt Capacitance Is the capacitive effect between two, closely spacedcurrent carrying conductors, which are insulatedfrom one another.

Cable capacitance is determined by the insulationthickness (Conductor Separation).

The gauge of the cable has no effect on thecapacitance.

Capacitance also is affected by pair length.

Manufactured cable pair shunt capacitance valve

averages about .052µF/Km for all cable gauges.

Series Inductance Is the magnetic field effect between two twisted,closely spaced conductors which are insulated fromeach other.

Depends on the electromagnetic fields set up by the A.C. currents in the conductors.

The measurement is measured in millihenries per

kilometer.

Shunt Conductance A measure of the ability of a substance to conductelectricity.

It is the reciprocal of resistance, ohm

Shunt conductance however contributes to thereduction in signal as it passes through cable pairsbased upon dissipation factor of the insulating

material.


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Impedance


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TRANSMISSIONCHARACTERISTICS

Two secondary constants delivered from the fourprimary constants are:

• Attenuation• Characteristic Impedance.

Attenuation Is the energy loss of a signal measured in db?

It is dependent on the frequency of the signal andincreases with an increase in frequency.

CharacteristicImpedance

Is the loss of ac signal (voice) due to the impedanceof the loop, which is the resistance of the loop to acpower (voice frequency 300 Hz to 340 Hz).

Impedance is measured in Ohms and uses thesymbol Z.

For maximum power transfer then the inputimpedance should equal the output impedance.

In voice applications, a compromise impedance of600 or 900 01xms is used to match the cable pairs.

600 Ohms impedance is preferred for pots and 900Ohms is used in the C.O. switching systems.


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Impedance Mismatch An impedance mismatch prevents maximum powertransfer in the circuit.

A change in the cross-section of the conductors ora change in insulation thickness causes changes inresistance and capacitance in the cable.

Some forms of impedance mismatch are:

• Half taps• Opens• Change of gauge or size• Splices.

Reflection occurs when there is an impedancemismatch.

Some of the energy from the source gets reflectedback and never reaches the load because the loadis at the far end.


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CABLE, NON-LOADED This course will only cover non-loaded cable(maximum length 5486 m)

The four main characteristics of non-loaded cablefor voice frequency operation are:

• Net Loss• Slope• Impedance• Return Loss.

Net Loss Is measured in db, at any given frequency from300Hz to 3400 Hz (usually at 1004 Hz) from theinput end of the cable pair to the output end.

Whenever we transmit energy from one point toanother over a transmission line, we lose a portionof the energy.

This is because of the inherent electricalcharacteristics of the line.

Recalling the four electrical constants of cable pair,then an efficient transmission line is one which hasgood balance between those components andtherefore absorbs a minimum of the transmittedenergy.

It is then the amount of the voice band energy indb’s which is absorbed by the transmission line.


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Loaded Cable Loss


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CABLE, NON-LOADED (CONT.)

Slope Frequency response or frequency distortion is ameasure of the high frequency response of a line.

Level of the circuit is measured at two frequencies,100 Hz and 280 Hz and the difference in levelsdetermines the slope.

A properly designed circuit has a relatively flatfrequency response from 400 Hz to about 2800 Hz,above which, the loss increases quickly.

High frequency roll off increases as circuits getlonger.

Circuits that are beyond 5-5 km the slope would beunacceptable unless it is compensated in some way(loading).

Impedance Is the “opposition to A.C. current flow”.

It acts like resistance except that impedance varies

with frequency.

At low frequencies a cable pair has a fairly highimpedance and at a high frequency it has a lowimpedance.


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Return Loss A less confusing term for Return Loss would havebeen Reflection Loss because that more accuratelydescribes what is actually happening.

Assume that we are sending a 1000 Hz tone downa cable pair to a terminal that is 6 db’s away, alsoassume that the cable pair is open or un-terminated.

What happens? Roughly, what happens is this:

The energy of the 1KHz tone gets to the end of thecable and sees this open condition or extremely

high impedance.

Because of the open condition, there is no A.C.current flow at the terminal. In order to absorb ordissipate energy, or power, there must be currentflow. If the energy is not transferred to a load, ortermination, and is not dissipated, where then doesit go?

There is only one place left that it can go and that isback down the cable pair in the direction from

where it came.

Using a certain test arrangement with a test hybrid,we can actually see this being returned to thesending end.

Allowing for the loss of the test hybrid, we will seethat the level of the tone is – 12 db.

This equals two times the total one way loss.

All the energy that arrived at the far end wasreflected and it suffered 6 more db’s of loss on thereturn trip.


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Return Loss (Cont.) Further, we could say that the reason that theenergy was returned is because of an impedancemismatch at the terminal end.

If the cable pair had not ended at that point, but hadcontinued on indefinitely than all of the energywould be eventually dissipated by the impedance ofthe cable and none would have been reflected.

Or, if we had placed a termination on the end of thecable at the 6 db point, then the energy would havebeen dissipated by the termination and again nonewould be reflected.

To transfer energy with maximum efficiency, it isnecessary that the impedances of the oscillator,cable pair, and termination be exactly equal.

We have seen what happens in the case of a totalmismatch such as an open pair.

The same thing happens to mismatches of lesserdegrees with the difference being the amount ofenergy being reflected.

The less difference in impedances, the less energyis reflected.

The same applies to mismatches where theterminating impedance is less than characteristicimpedance of a cable pair.

A total mismatch in this case would be short appliedacross the tip and ring at the end.

Before, we said that without current flow there wasno energy dissipation.

The same is true of resistance, if there is currentflow but no resistance then there will still be noenergy dissipated.


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Return Loss (Cont.) At this point we can say that to get maximumtransfer of energy from the source to the terminationwith minimum reflection, all interface impedancesmust match.

The amount of reflection is directly proportional tothe amount of mismatch.

The level of energy which is representative of areflection from the terminal end caused by amismatch is referred to as “Echo Return Loss”(ERL).

So far we have assumed that all of the energyreflection has been caused by a mismatch at theterminal end of the transmission line and that theline itself was ideal.

In practice however, this is not the case.

The transmission line or cable pair also causesreflections.

The amount of reflection depends on how well the

line is designed and built.

To explain what happens to a cable pair to causereflections let’s divide the cable into short sectionswith each section being one meter long.

Now each one of these one meter sections has theelectrical constants that we previously described.

However, because the cable manufacturer is unableto precisely control the physical make up of a cable,

thus ensuring that each one meter section is exactlylike every other one meter section, their electricalcomponents change.


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Return Loss (Cont.) For instance the insulation thickness could bethicker in one section from another.

This causes the conductor spacing to increase thusthe capacitance will be less and the impedance willbe higher in that section.

When we connect this section to other sections wehave an impedance mismatch and consequently areflection.

The amount of reflection is dependent upon thedegree of mismatch.

In this case the mismatch is small, so the reflectionis small, so small in fact that we probably could notmeasure it.

But this is only one section and the cable is madeup of bunches and bunches of these sections and aconsiderable amount of these sections will bemismatched.

Each mismatched section causes a small reflection

at the sending end.

If the cable is very poorly constructed, this reflectionamounts to a substantial amount of energy.

The level of energy measured as the source whichis caused by irregularities in the transmission line isreferred to as Structural Return Loss.

In contrast to the Echo Return Loss which can beeliminated or reduced by matching the impedance

of the transmission line and termination, there is justno way to reduce the Structural Return Loss oncethe line is built.


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SUMMARY Primary constants (Resistance, CapacitanceInductance and Resistance) have a direct bearingon the transmission of voice signals and are largelyresponsible for the amount of energy lossintroduced by a cable pair.

Two secondary constants, derived from the fourprimary constants are attenuation and characteristicimpedance.

Also two other impairments to transmission are:

• Impedance Mismatch• Reflection.


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UNIT 2

Noise Theory &

Mitigation Devices


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NOISE THEORY & MITIGATION DEVICES

INTRODUCTION In this unit, you will learn how to identify the typesand sources of noise in the subscriber loop.

In addition, you will review theory and application ofdesign techniques for noise mitigation.

The following subjects will be discussed:

• Noise• Conditions for power induction

• Design techniques to minimize noise• External noise – mitigation devices.


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Steady State Noise – Circuit Noise

Power – dBm versus dBrn


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NOISE

Definition Noise is any undesired sound or disturbinginfluence within the frequency band of interest (0 –4 kHz voice, data higher)

Noise Origins Noise originates from an external source or is theresult of abnormal conditions within the cable, suchas:

• Wet cable• Power interference• Radio interference• Bad splice• CO noise• Cross talk.

Noise Limits Measured in decibels above a reference noise levelin dBrnc; thus, 0 dBrnc = -90 dBm.

The noise objective for a subscriber’s loop is to

have a noise level less than 20 dBrnc (dB refers tonoise through “c” message filter)


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NOISE (CONT.)

Classification andSources of Noise

Noises are considered to be in two groups:

• DC Noises• AC Noises.

DC Noises Thermal Noise:

• Caused by heat• High electron activity

• Current flow through a circuit.

Static Noise:

• Electron discharge caused by difference inpotential.

Battery Noise:

• Noise from battery chargers in CO.

Impulse Noise:

• Clicks on line—too short a duration to affectspeech

• Affects data on line—dial pulses, keyingdevices, etc.


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NOISE (CONT.)

Classification andSources of Noise (Cont.)

AC Noises Cross Talk:

• Induced from adjacent circuit• Due to faulty cable or abnormal levels of

adjacent circuits.

RF Interference:

• Unshielded wiring picks up RF signal• Common near transmit antenna.

Power Line Induction:

• Induced form adjacent power lines• Most common single source of noise on

subscriber loop• Audible noise is a harmonic of 60 Hz, which

is below response of telephone set.

Note: OP has no control over DC Noises, as they are COor equipment origins. AC Noises can be prevented orreduce by following design rules.


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Electro Static Induction

Power Influence from Hydro


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CONDITIONS FORPOWER INDUCTION

Three factors must be present for induction tooccur.

These factors are:

• Influence• Susceptibility• Coupling.

Influence The tendency of the power system to affect thetelephone system:

• Electro Static Induction• Electro Magnetic Induction:

o Harmonics of 60 Hz is the noise actuallyheard on the telephone line

o A balanced three-phase power line hasfew harmonics; the exceptions are oddtriplets which are the greatest source ofinduce noise

o For example: 3, 6, 9, 12, 15 (9 x 60 Hz =540 Hz)

o All single phase power systems areunbalanced, consequently rich inharmonics

o Influence can only be reduced by PowerCompany.


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Electromagnetic Induction

Degree of Balance of Telephone Line


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CONDITIONS FORPOWER INDUCTION(CONT.)

Susceptibility The tendency of the telephone system to pick upthe effects of the power system affects the degreeof balance of telephone line.

Causes of line unbalance include:

• Bad splice• Divided ringers• Defective cable• Grounded carbons• Customer equipment.

Effect of interfering frequency.

Degree of shielding:

• If shield is open or non-grounded, thentelephone plant is susceptible to induction.


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“C” Message Filter


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CONDITIONS FORPOWER INDUCTION(CONT.)

Coupling Similar to primary and secondary windings of atransformer.

Coupling is dependent on:

• Length of exposure• Separation between power and telephone• Effectiveness of telephone shielding• Earth resistance.


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Electro Static Induction

Cable Shield Reduces Power Influence


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DESIGN TECHNIQUESTO MINIMIZE NOISE

The following are design techniques used tominimize noise by elimination of electro staticinduction:

• Twisted pairs• Continuous shield.

Shield current induced from Hydro is largely due tolow resistance.

Shield current then induces into cable pairs acurrent opposite in direction to Hydro induction.

Resultant power influence longitudinal current issmall.

Power influence less than 80 dBrnC is acceptable.

Reduction of Electro Magnetic Induction:

• Continuous shielding• Bonding and grounding.


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Bonding

Grounding


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DESIGN TECHNIQUESTO MINIMIZE NOISE(CONT.)

Shields of all cables must be electrically continuousfor safety and noise.

Maximum distance between shield to messengerbond is 400 metres.

At Ready Access Terminal, provide shield to strandbond as well as shield to shield continuity.

Grounding is required for:

• Safety from electrical shock• Preventing high voltage flashover• Effective noise shielding of pairs• Operate power circuit breakers• Lightning discharge.

Cable grounds are:

• Power MGN (Multi Grounded Neutral)• Telephone ground rods.


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Noise in Unbalanced Pair

Noise Choke


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EXTERNAL NOISEMITIGATION DEVICES

Noise Chokes orLongitudinal Chokes

If noise is due to longitudinal induced AC current, asa result of longitudinal induced AC voltage, then theuse of a longitudinal choke can reduce thiscondition.

A longitudinal choke can be thought of as a twowinding, mutually coupled, well balancedtransformer.

These chokes are connected in series with tip and

ring and present high longitudinal impedance toinduced AC.

It only adds some DC resistance of the coil to themetallic circuit.

Induced noise will be out of phase across chokeand will be cancelled.


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Neutralizing Transformer

Tip and ring are twisted together.


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EXTERNAL NOISEMITIGATION DEVICES(CONT.)

Neutralizing Transformer Neutralizing Transformer has the followingcharacteristics:

• Is most commonly used noise mitigationdevice

• Its function of neutralizing transformer isprimarily for safety, not for noise reduction

• If induced voltage is higher than safety limits,then neutralizing transformer may beconsidered; noise reduction is a by-product ofreducing voltage; noise is not alwaysreduced; depends on location of transformerin relation to location of induced noise

• Acts on complement of pairs rather thanindividual pair

• Comes in sizes ranging from 6 to 100 pairs

• Operates on transformer principle that avoltage applied to primary is 180 degrees outof phase with voltage induced in secondary.

• A single exciter pair is connected to theprimary (tip and ring are twice as big)

• All other pairs are connected to the multi pairsecondary

• Neutralizing transformer is placed in theelectrical midpoint of the circuit—locationwhere induced AC voltage on each side ofopen pair is equal when measured to ground

• Can sometimes be located in the customer’spremises.


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Neutralizing Transformer(Cont.)

• Location determined by Transmission group

• Requirement for NT also determined byTransmission group

• Cable technician to specify exciter pair onwork order.

Neutralizing Transformer adds anywhere from 60 to150 meters of cable to the loop.

It doesn’t affect load coil spacing significantlybecause windings are not shielded, therefore, noincreased capacitance to ground.

Disadvantages of Neutralizing Transformer include:

• Expensive

• May mask true cause of noise, i.e., poor

design

• Pairs are closely coupled through windings,so any trouble on one pair may affect others;grounded pair on secondary would groundout secondary, thus causing higher noise onother pairs

• Transformer coupling rather than spacecoupling gives better cancellation.


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Harmonic Suppression Reactor

Smart Switch


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Harmonic SuppressionReactor

Harmonic Suppression Reactor shifts the resonantfrequency of a capacitor bank.

Power company uses cap bank on 3 Phase toimprove P-factor by helping balance load and alsoas a smoothing means at industrial parks.

Capacitor banks can cause TELUS noise problems.

Smart Switch Smart Switch floats ground connection to acapacitor bank.

It operates under a ground fault condition.

This equipment is HYDRO equipment.


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Ground.... and Ground We Go!

Don’t take grounds for granite!

The usefulness of a specific type of ground depends onthe application characteristics of your particular circuit.


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Solid State Protectors Solid state over voltage protection (SSOVP) is thestandard multi-pair protector for TELUS.

They last longer, with less noise than the previouslyused carbon 5 pin protectors.

They also provide superior protection because they“fire” faster and at lower voltages than carbon.

Span Line protectors are red 5 pin, solid state, 300volt protectors.

Pair Gain remote feeder protectors are 240 voltfiring solid state protectors.

Induced longitudinal voltage is lower at theCO/remote switch site than at the customer end ofthe loop.


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UNIT 3

Voice Frequency

Broadband Testing &Measurements UsingDynatel 965DSP/SA


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3M Far-End-Device II & 965DSP/SA

Line Qualification Testing


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VOICE FREQUENCY BROADBAND TESTING &

MEASUREMENTS USING DYNATEL 965DSP/SA

INTRODUCTION In this unit we will cover accepted criteria for POTSservice (Voice Frequency) and how to utilize the965DSP/SA to quantify cable pairs prior to newservices.

Topics that will be covered are:

• Accepted Measurements for POTS Serviceand Broadband

• Dynatel 965DSP/SA Test Functions:o DSLo TDRo dBo Auto test - without and with Fed II.

• Line Qualification Testing with the Dynatel964DSP/SA without the Fed II

• Wideband/Broadband Test with the Fed II• Talk Set.


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ACCEPTED MEASUREMENTSFOR POTS SERVICE AND BROADBAND

AcceptanceMeasurements for POTSService

Loop Current – Should be greater than 23 ma.

Circuit Loss – less than 8.5 db.

Power Influence – less than 80 dbrnC (loss througha ‘C’ filter.

Circuit Noise – less than 20 dbrnC.

Balance:• Greater than 60 db• Power influence and circuit noise are

interrelated (formula PI-CN=Balancer).

Longitudinal Balance – greater than 60 db.

Ground Resistance:• Less than 25 ohms• This is the resistance between the C.O.

ground and the customer ground.

Slope:• Less than 7.5 db• Is between the high and low frequencies of a

circuit.

Insulation Resistance – 3.3 M ohms or more.


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Qualification Testing

ISDN(144K on 1 pr.)

HDSL(1.54M on 2 pr.)

ADSL(8M on 1 pr.)

Loop Length

Use Opens & Loop Ohmsor 965DSP TDR


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Accepted Measurementsfor Broadband

Without good clean copper pairs these circuits won’tfunction.

Most operational problems can be traced to simplecircuit faults such as leakage, opens, load coils andbridge tap.

See the Qualification Suggested Test Limits on theleft page.

Note:For more information see TOPPS 2.6.1.3.


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965DSP/SA

Note:Make sure the 965DSP test set has the proper software version (Version 7)


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DYNATEL 965DSP/SATEST FUNCTIONS

The Dynatel 965DSP/SA is used to:

1. Reclaim defective cable pairs for new service2. Analyze pairs and locate faults on POTS and

Wideband lines3. Pre-qualify lines for POTS and wideband

installations4. Post-qualify lines for POTS installations.

In the previous course Cable Fault Locating, thefocus on the 965dsp/sa was using the following testfunction keys:

1. Voltmeter – measure ac or dc voltage2. Current meter – measure loop current3. Ohmmeter – measure resistance4. Tool box – access any of the functions in the

Tool box5. Open locator – find the distance to a break in

a cable pair6. Tone oscillator – send a tone on a cable pair7. Resistance fault locate – find the distance to

an insulation resistance fault on a pair.

The focus in this Unit will be using the remainingkeys for various test functions. They are:

8. DSL – to perform specialized tests on ISDNand DSL lines

9. TDR – shows the pair as a trace on thescreen, TDR measures distance to eventsbased on input about the pair

10. dB key – this function is used to measureloss, noise, longitudinal balance, widebandloss or perform a level trace

11. Auto test key – perform an automaticsequence of tests on an inactive, active orwideband pair, utilizes the Fed II

12. Talk set – allows you to use the 965dsp/saas talk set on active pairs, or to send dtmftones on inactive pairs.


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965DSP/SA - DSL Function

DSL Menu & Service Selection


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DSL Function Use this function to perform tests on ISDN and DSLlines.

Use the ‘up’ and ‘down’ arrow keys to move to thedesired test then press the ‘enter’ key to accept thechoice.

For DSL loss and DSL noise measurements, youfirst need to select the type of DSL service that youwant to test.

This automatically selects the appropriate linetermination impedance and noise weighting filter for

the selected service.

Parameters for the different services are indicatedin the table below.

Service Termination Filter Frequency Range

ISDN/IDSLHDSLADSL

135 135 100

EFG

1KhZ - 50KhZ4.9kHz – 245kHz20kHz – 1.1MHz

Press the [Setup] key to choose a DSL service.

Use the ‘up’ and ‘down’ keys to highlight thedesired service.

Press ‘enter’ to select the service and return to theprevious screen.

Note: ADSL modem will be covered in Unit 4 in PC link.


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ISDN Link Established


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DSL Test Menu Connect the Red and Black lead to the pair andpress the [Enter] key.

The 965DSP/SA displays the work “Connecting”while the instrument goes through three steps:

1. AIP (Activation in Progress),2. Sync (Synchronization), and3. Link (successful connection).

If any of these three tests is unsuccessful, thewords “Link Failed” will show in the screen.

Once a link is established with an ISDN signal, thescreen will display “Connected” in the main screen.

For the US, Canada and Korea, the [Enter] key willappear.

Press the [Enter] key to perform an Error Test onan active NI1 (National Implementation) ISDN pair.


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ISDN Error Test


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ISDN Error Test The 965DSP/SA can perform a near end and farend block error test after linking to a NII ISDN line.

The 965DSP/SA will count and display the numberof near-end and far-end errors.

“Near-end” errors are the errors detected at the965DSP/SA.

“Far-end” errors are errors detected at an ISDN linecard. (The far-end count is transmitted to the965DSP/SA over the ISDN link).

The screen displays the elapsed time since the startof the ISDN Error Test.

Standard practice is to monitor the line for a fixedperiod of time (for example, 5 or 15 minutes) andcount the number of errors.

Near-end and far-end errors are “blocks” of biterrors.

If there are no block errors in a given period of time,

this insures there will be no bit errors in the sameperiod.

The 965DSP/SA will automatically stop countingerrors after 15 minutes.

The word “Link” will be displayed as long as the965DSP/SA is linked to the ISDN line.

If the link is lost, the screen will display “No Link.”

Press the [Enter] key to start the test again.


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DSL Loss

DSL Noise


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DSL Loss

See page 64

Use this function to measure loss from the far endto near end using a tone between 20 Khz and 1.2Mhz.

You must have a tone at the far end.

The screen displays the signal level in dBm, thefrequency of the tone in Khz, the selected servicetype and the line terminating impedance.

Press [Enter] to return to DSL menu.

DSL Noise

See page 64

Use this function to measure wideband metallic andlongitudinal noise on a pair.

Connect the Red and Black test leads to the pairand Green lead to ground.

Press the [Tab] key to move between metallic noisepower measurement across the pair andlongitudinal noise power of the conductors toground.

The highlighted reading is “live” and continuouslyupdated.

The screen displays noise power (referenced to -90dBm), selected service type, noise weightingfilter, and the metallic terminating impedance.


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Broadband Interface FrequencySignatures

HDSL T1

ISDN


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Spectrum Analyzer Interfering noise signals on a pair often occur as aresult of crosstalk from other Wideband/Broadbandservices.

Each Broadband service type has a uniquefrequency signature.

Provides a graphic display of the signals, a noise ona line, over a selected range of frequencies.

Connect the Red and Black test leads to the pair.

Use the [Up] and [Down] arrow keys to select the

frequency span of interest.

The endpoints of the frequency span bar willchange to indicate the frequency range.

Use the [Left] and [Right] arrow keys to move thecursor across the screen.

The frequency of the cursor position appears on thecenter of the span bar.

The 965DSP/SA continuously analyzes the signalsand noise present on the pair.

The screen displays the average power of all thesignals and noise in the selected span in dBm at theupper left.

The actual signal level at the cursor position isdisplayed in dB at the upper right.


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Broadband Interface FrequencySignatures

ADSL Down Stream

ADSL Up Stream


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Spectrum Analyzer(Cont.)

Interfering noise signals on a pair often occur as theresult of crosstalk from other Wideband services inthe same cable.

Each Wideband service type has a uniquefrequency signature.

Use the spectrum analyzer to classify the source ofthe noise interference on a pair.

The 965DSP/SA Subscriber Loop Analyzermeasures extremely low noise levels and requiresproper handling of the test leads to ensure

consistent measurements.

Extend the test leads away from the 965DSP/SAwhen conducting DSL tests and make sure that theRed and Black leads are kept as close together aspossible to minimize RF noise pickup.

Note:Do not attempt to conduct DSL noise or lossmeasurements while the external DC charger is

connected.


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965DSP/SA Keypad - TDR Key

TDR Setup


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TDR This function shows the pair as a ‘trace’ on thescreen.

Measures distance to events based on input aboutthe pair.

Six modes to view a pair:

1. Single Trace – view a single pair2. Dual Trace – view two pairs3. Differential – view difference between two

pairs4. Crosstalk – view the electrical coupling

between two pairs5. Memory – compare a ‘Live’ trace with a trace

stored in memory6. Peak – displays a history of maximum and

minimum values with the live trace.

Press the ‘Up’ and ‘Down’ keys to move to adesired selection.

Press ‘Enter’ to accept the choice and start themeasurement.

TDR Setup Features a setup function that allows you to enterthe cable type, gauge and first length.

VP (Propagation Velocity) is automatically set fromthese selections.

Press ‘Setup’ to chance cable type gauge or toselect either minimum first length or last used.


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TDR Controls

Length:100 ft, 200 ft, 500 ft, 1 kft, 2 kft, 5 kft, 10 kft, 20kft, 30 kft.(30m, 60m, 150m, 300m, 600m, 1.5 km, 3 km, 6 km, 10 km)

Filter: is Out, is In

Filter allows you to switch in a filter to remove noise.You should use the filter if you see noise on the display.

Note: Switching in the filter may make it difficult to detect small events onthe cable.

Pulse Width: 5 ns, 34 ns, 235 ns, 1600 ns


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TDR Controls Are valid for all modes except the ‘Memory’ mode.

Controls and parameters are displayed at thebottom of the screen.

Use ‘Tab’ and ‘Enter’ keys to move forward orbackward through the TDR controls.

Individual controls and their parameters are:

• Length:o Allows you to set the distance from the left

side of the screen to the right side.o The left side is usually at the test set and

the right side is the furthest that can bedisplayed with the length selected.

• Filter:o Allows you to switch in a filter to remove

noiseo Use the filter if you see noise on the

display.

Note:Using the filter may make it difficult to detect smallevents on the cable.

• Pulse Width:o Allows you to select the width of the pulse

sent out on the pair.o The 965DSP/SA automatically selects the

best pulse for each length selectedo Use a shorter pulse width to give better

resolution of events (will not go as far on

the pair)o Use a wider pulse width to see further on

the pair (resolution will not be as good asa shorter pulse.

o Pulse width is displayed at top right ofscreen.


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TDR Controls (Cont.)

Gain: 0db, 6db, 12db, 18db, 24db, 30db, 36db, 42 db, 48db, 54db,etc, through 198 db - for a total of 34 gain settings.

Vp: 0.50 to 1.00 (75 to 150 m/uS)

Values for Cable Types & Gauges

PIC: 19 AWG22 AWG24 AWG26 AWG

0.69 (108 m/us)0.68 (102 m/us)0.67 (100 m/us)0.66 (99 m/us)

JELLY-FILLED:19 AWG 22 AWG 24 AWG 26 AWG

0.66 (102 m/us) 0.65 (97 m/us) 0.64 (96 m/us) 0.63 (94 m/us)

PULP: 22 AWG 24 AWG 26 AWG

0.69 (103 m/us) 0.68 (102 m/us) 0.67 (100 m/us)


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TDR Controls (Cont.) • Gain:o Allows you to select the vertical gain of

the TDRo Higher gain will make events look taller on

the screen and is helpful for finding smallfaults

o Gain settings are referenced to VB level

• Vp (Propagation Velocity):o Allows you to adjust the velocity factor of

the pair or cable:o Different cable types have different

values of Vpo To be accurate, the Vp should be set to

the exact value of the cable being testedo If in doubt use a known length of cable to

calibrate Vpo Water in the cable increases the value of

Vpo If cable has water in it, it will appear

shortero Vp displayed at top left of screen.


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TDR Controls (Cont.)

Zoom: x1, x2, x4, x8, x16

Note: Subtract the five foot length of the test leads from measurement.

TDR Traces

Before Offset After Offset


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TDR Controls (Cont.) • Zoom:o Allows you to set the horizontal gain of the

TDRo Higher zoom will spread out the trace and

make it easy to resolve the start of anevent

• Move Cursor:o Always align the cursor to the left side of

an event in questiono Use the ‘Left’ and ‘Right’ arrow keys to

move the cursor across the screeno The distance from the 965DSP/SA to the

cursor is always shown in the center ofthe distance bar.

o The ‘Start’ and ‘Stop’ numbers shown inthe distance bar are the distances fromthe test set to the left and right side of thescreen.

o The Stop distance may be different fromthe Length selected due to the screenresolution.

o The Start and Stop distances are alsoaffected by zooming and panning(described below).

o If you move the cursor to the right side ofthe screen, the screen will “pan” to theleft.

o If the cursor is moved to a position on theTDR trace that is out of viewing range(above the top of the screen or below thebottom), the trace is shifted up or down tobring it into view. The x axis will not move.

o The vertical offset will be maintained untilthe cursor is moved to another point that

is out of viewing range or until one of thedisplay controls is changed.

o The vertical offset function affects allmodes except memory.


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TDR Single Trace

TDR Dual Trace


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TDR Modes Single Trace:

• Connect the red and black test leads to thepair you want to test

• View a single pair at a time.

Dual Trace:

• Connect red and black test leads to the pairunder test

• Connect the blue and yellow leads to thereference pair

• Pair under test is displayed at top of thescreen

• Reference pair is at the bottom of the screen

• Changes in control parameters affect bothtraces

• Not possible to control each traceindependently

• Usually you are comparing a faulted pair witha good pair.


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Differential Mode

Crosstalk Mode


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TDR Modes (Cont.) Differential Mode:

• Used to display the difference between twopairs (usually a good and bad pair

• Test lead hook up same as dual trace.

Crosstalk Mode:

• Used to display the amplitude and location ofsignals that “cross” from one pair to the other(could be caused by a split)

• Test lead hook up same as dual trace.


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Stored Traces

Display Stored Results


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TDR Modes (Cont.) Memory:

• Used to compare a pair under test (at top ofthe screen) with a stored trace that is inmemory (at the bottom)

• First screen will show a list of the ID numbersfor all the stored traces

• Use ‘Up’ and ‘Down’ keys to highlight theselection

• Use ‘Right’ key to delete the selected storedresult

• Use ‘Left’ key to delete all of the storedresults

• Press ‘Enter’ key to select the highlightedresult and display the stored results list forthat ID number by type (TDR) date and time

• Use ‘Up’ and ‘Down’ keys to highlight the

stored result

• Use ‘Right’ and ‘Left’ key to delete theselected result

• Press ‘Enter’ to display the stored trace onthe bottom of the TDR screen and ‘Live’ traceon the top.


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View Live & Stored Trace Results

Combined Trace


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TDR Modes (Cont.) Memory (Cont.):

• Cursor may be moved by using the ‘Left’ and‘Right’ keys

• Control settings for the stored trace can beviewed by pressing the ‘Tab’ or ‘Enter’ keysbut the settings cannot be changed

• Memory function includes a ‘Diff’ control,accessible from the memory screen bypressing the ‘Tab’ key

• Default is Diff off

• Use ‘Up’ and ‘Down’ keys to turn Diff on

• Diff combines the live trace with the storedtrace to show the difference in the tworeadings

• The TDR memory screen defaults to thecontrol settings that were active when the

stored trace was saved using the ‘TDR Save’function.


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TDR Peak Screen

Save Active Single Trace


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TDR Modes (Cont.) Peak:

• Used to capture events that maybeintermittent

• Mode continuously detects and displays themaximum and minimum traces that occurfrom the time that the mode is first selected

• The ‘Live Trace’ is displayed continuously

• As a new maximum or minimum trace isdetected, it will replace the previous one onthe display

• If the pair being tested is stable (nointermittent faults), the minimum, maximumand live traces should appear as a singletrace

• If any control valves are changed the peakhistories will be erased and new values willbegin to display.

TDR Save You can save any active ‘single trace’ TDR screen.

Select the TDR control parameters so the screenappears as desired.

Press ‘Save’ to save the trace.

Use blue keys to enter an alphanumeric ID.

Press ‘Enter’ once the ID has been entered to savethe current TDR trace information.


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Event Recognition


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Event Recognition Events:

• Are the ‘Dips’ and peaks seen on the screencaused by faults or devices on the pair.

Launch Pulse:

• First peak on the screen is the “launch Pulse”which occurs where the 965DSP/SAconnects to the test leads (at a distance of 0meters)

• The distance to the cursor includes the 1.5mlength of the test leads.

Fault:

• A resistance fault will show up as a dip on thescreen

• The lower the value of resistance, the lowerthe dip.


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TDR Trace of a GoodPair

A TDR looks at a cable pair as a series ofimpedances (Impedance 1,2,3,4,& 5), as shownabove, where the output pulse current will flowthrough.

A closer look at the TDR trace shows that the pulsestarts at 0 impedance and then increases to 600Ohms as it enters the pair.

Note: 600 ohms is standard impedance used in telephonecables.

This big change in impedance generates a very tallreflection at the beginning of the pair and this iscommonly referred to as the “Launch Pulse”.

After the initial big reflection, a ripple on the tracecan be seen as the pulse tries to stabilize at 600Ohms and then the impedance remains the sameuntil it senses another change.

When the impedance remains constant or stays the

same, the TDR trace also stays flat and stays flatuntil another change in impedance comes along.

As the pulse reaches the far-end of the cable,another big change in impedance occurs.

This time from 600 Ohms to infinity.

This creates another tall reflection at the end of thetrace. This final reflection represents the end of thecable.


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TDR Trace of a Good Pair

TDR Trace Analysis – Partial Open


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TDR Trace of a GoodPair (Cont.)

It is also interesting to note that the impedancechange at the end of the cable, although a lot biggerthan that at the beginning, did not generate a muchtaller reflection because as the pulse travels alongthe pair towards the far-end, a good amount ofpulse energy is also dissipated (consumed) alongthe way.

Whatever is left of the energy at the end of the pairwill ultimately determine the height or depth of thatlast reflection.

TDR Rules Rule 1:

Anything that causes the circuit impedance tochange creates a reflection or event on the TDRtrace.

If the change is an increase in impedance thereflection will be positive-going or “Peak” (above thebaseline).

If the change is a decrease in impedance thereflection will be negative-going or a “Dip”.

Partial Open is a kind of cable fault that “restricts orlimits” the flow of pulse current in a circuit.

This increases the impedance of the section(impedance #3) which then creates a “Peak” on thetrace.

Rule 2:

If the cause of impedance change ‘restricts or limits’

the flow of pulse current, this makes the impedancego higher thus the reflection generated will be a‘Peak’.

Examples: Opens, Partial Opens, Load Coils andSplits or anything that causes pair capacitance todecrease will generate a “Peak”.


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TDR Trace Analysis - Short

TDR Trace Analysis (Cont.)


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TDR Rules (Cont.) Short is a kind of cable fault that ‘absorbs or drains’pulse current in a circuit.

The result is a decrease in the impedance of thesection (impedance #3).

This creates a ‘Dip’.

Rule 3:

If the cause of change ‘drains or absorbs’ pulsecurrent, the impedance of the circuit go lower.

This then will create a ‘Dip’ on the trace.

Examples:

Shorts, Grounds, Crosses or anything thatincreases a circuit capacitance like Bridge Taps,Build-out Capacitors, wet spices or wet cablesections and corrected splits will generate a ‘Dip’.

Rule #4:

The ‘magnitude’ of the change in impedance andthe ‘amount’ of pulse current available at thatparticular instant will determine the height of the‘Peak’ or the ‘depth’ of the ‘Dip’.


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TDR Rules Summary Rule 1:

Anything that causes the circuit impedance tochange creates a reflection or event on the TDRtrace.

In other words if circuit impedance remains thesame the TDR trace will stay flat (no reflection).

If the change is an ‘increase’ in impedance thereflection will be positive-going or a ‘Peak’.

If the change is a ‘decrease’ in impedance the

reflection will be negative-going or a ‘Dip’.

Rule 2:

If the cause of impedance change ‘restricts or limits’the slow of the pulse current the reflection will be apositive-going trace “Peak’.

Examples:

Opens, Partial Opens, Load Coils, and Splits or

anything that causes pair capacitance to decrease.The effect of all these is an ‘increase’ in circuitimpedance thus generating ‘Peak’.


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TDR Rules Summary(Cont.)

Rule 3:

If the cause of impedance change ‘drains or absorbs’pulse current the reflection will be a negative-going ora ‘Dip’.

Examples:

Shorts, Grounds, Crosses or anything that increasescircuit capacitance like Bridge Taps, Build-outCapacitors, wet splices or wet cable sections andcorrected splits.

The effect of all these is a decrease in circuitimpedance thus generating a ‘Dip’.

Rule 4:

The magnitude of the change in impedance and theamount of pulse current available at at that particularinstant will determine the ‘hieght or depth’ of thereflection.

The bigger the change plus the availability of more

pulse current will result in a much taller or deeperreflection but even if the change in impedance is big ifthere is not much pulse energy available will result insmaller ‘Peak’ or a shallower ‘Dip’.

Also although pulse current is abundant but thechange in impedance is small, the result will still be asmall ‘Peak’ or a shallow ‘Dip’.


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Masking


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Masking When two or more faults exist and one is moresevere than others behind it, the most severe oneovershadows all the others.

If the first fault is very severe compared to theothers, it is possible that the other faults behind itmay just be too small or may not be seen at all onthe TDR screen.


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TDR Trace Samples – Complete Open

TDR Trace Samples – Branch Cable


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TDR Trace Samples Complete Open:

• Is a kind of cable fault where the conductor iscompletely cut and that the flow of pulsecurrent through the circuit is no longerpossible.

• This is a severe fault which increases theimpedance of the circuit substantially.

• Because the fault is severe it then creates atall ‘Peak’ on the trace.

Branch Cable:

• A branch cable constitutes an addedcapacitance to the pair.

• This added capacitance absorbs additionalpulse current.

• This results in a decrease in circuitimpedance thus creating a ‘Dip’ at the bridge-

tap.

• At the far-end of the branch cable again therewill be another change, a decrease incapacitance and this increases circuitimpedance thus creating a ‘Peak’.

Note: The traces of branch cable and a wet cable sectionare similar. Both create a ‘Dip’ followed by a ‘Peak’in the trace.

.


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TDR Trace Samples – Load Coil

TDR Trace Samples - Split


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TDR Trace Samples(cont)

Load Coil:

• A Load Coil rejects the flow of pulse in thecircuit.

• This increases circuit impedance thuscreating a ‘Peak’.

• The reflection is unique because the tip issmooth and rounded.

• This distinguishes it from all other ‘Peaks’.

Split:

• A Split reduces the existing capacitance ofthe pair.

• The effect is that it will increase theimpedance of the circuit at the point wherethe two conductors separate thus creating a‘Peak’.


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TDR Trace Samples – Corrected Split

TDR Trace Samples – Wet Splice


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TDR Trace Samples(cont)

Corrected Split:

• A ‘Split’ reduces the existing capacitance ofthe pair which results into an increasedimpedance of the circuit thus creating a‘Peak’.

• A ‘Corrected Split’ will restore thecapacitance of the pair back to its originalvalue.

• The change results in a decrease in circuitimpedance thus creating a ‘Dip’ in the trace.

• A ‘Split and a Corrected Split’ will then showon the TDR trace as a ‘Peak’ followed by a“dip’.

Wet Splice:

• A West Splice represents an addedcapacitance which absorbs pulse currentcausing circuit impedance to change to alower value.

• This then creates a ‘Dip’ in the trace.

• After the wet splice the pair capacitance goesback to its original value causing anotherimpedance change.

• This time to a higher value thus creating a‘Peak’ in the trace.

• Because the interval between the two eventsis too short, a ‘wet splice’ will appear as a‘Dip’ immediately followed by a ‘Peak’.


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TDR Trace Samples – Wet Cable Section

TDR Controls


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TDR Trace Samples(Cont.)

Wet Cable Section:

• The trace of a ‘Wet Cable Section’ is verysimilar to a ‘wet splice’ but the separationbetween the ‘Dip’ and the ‘Peak’ is muchwider compared to that of a ‘wet splice’.

TDR Controls Table on left indicates the various TDR controls thatyou will use to locate problems on a cable pair.


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Maximum TDR Range per

Wire Gauge & Size


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Maximum TDR Range The table at left shows the limitations of using TDRfor the various cable gauges you will encounter.


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965DSP/SA Keypad – dB Key

dB & Transmission File


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dB This function is used to measure loss, noise,longitudinal balance, wideband loss or perform alevel trace.

Press the ‘Up’ or ‘Down’ keys to move to a test.

Press ‘Enter’ to accept the choice.

For loss, noise and longitudinal balance you will firstbe asked to dial a number before starting the test.

The ‘Dial Noise’ and Dial Longitudinal Balance’screen appears the same as ‘Dial Loss’ except for

the screen titles.

Separate lists of phone numbers are kept for eachfunction.

Press the ‘Right’ arrow key to bypass the dialingprocess and manually measure the loss.


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Loss Result

Transmission File

Measure Noise/PI


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TELUS REV 2006-10-11 123 # 070000

dB (Cont.)

Loss Use this function to measure loss from the far-endto near-end using a tone between 200 HZ and 20KHZ.

Press the ‘Tab’ key to go to noise.

Press the ‘Left’ arrow key to go to longitudinalbalance.

Press ‘Enter’ to return to DB menu.

Press ‘Up’ or ‘Down’ to adjust the speaker volume.

Use the blue keys to send DTMF tones.

Noise Use this function to measure the noise powerinfluence and the calculated balance of the pair andground.

Connect the red and black leads to the pair and thegreen leas to ground.

Press the ‘Tab’ key to go to longitudinal balance.

Press the ‘Left’ arrow key to go to loss.

Press ’Enter’ to return to the DB menu.

Press ‘Up’ and ‘Down’ to adjust the volume.

Use the blue keys to send DTMF tones.

8/15/2019 Advanced Cable Fault Locatin

Advanced Cable Fault Locating - Oct 11-06

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