Old Telephone cabling4 wire

RJ 11Color code

Used in commercial and residence NEW

Prior to DivestitureIn years gone past, it was the responsibility

of the phone company not only to bring phone service to your house but to do the phone wiring within your house as well.

This is no longer the case. When you order phone service to your house, the local phone company installs a network interface device, a sturdy grey plastic box usually mounted either in your basement or on an outside wall.

ResidentialBefore Divestiture

Phone company maintained

AfterDemarcYou pay if the problem is

on your premiseStatement by operator

when calling in a trouble report “if the problem is internal you will need to cover the cost of the service call”

Note: Star and Branching

Typical Residential Layout

Wiring the NID

CommercialBefore divestiture

Teleco maintained all wiring Teleco repaired the phones

Afterinternal wiring turned over for $1Phones given to the campus

Demarc established Normally at the EF or Entrance Facility

FVTC – maintained on the 2nd floor

Commercial continuedTypical install

Large multi-conductor cable ran into DemarcRan into EF Entrance FacilityBackbone cables ran to TR’s Telecom Rooms or

IC’s Intermediate Cross ConnectsFrom TR’s to 110/66 blocks 110/66 cross-connect field to 110/66

Distribution fieldDistribution field to station jack or

Mutoas or connection points then to stationsIC’ to TR’s via a backbone cable

Jack to RackPrimary focus will be on the cable that runs

from the TR to the work area station jack.Performance testscable termination

110/66 blocksPatch Panels

Equipment Racks19” Rack standard23” Rack standard

GroundingNeed

Power companies do not provide groundSafety issues

BISCI Standards, Doc cam pg 292, 296

Typical facility layoutPG 9 BISCI – Doc camDraw on board

MDF

IDF

IDF

IDF IDF

STA

CO

Typical Residential layoutWire color code Telephone Network

InterfaceDraw on board

Function Old Color New Color

Tip 1 Green White/Blue

Ring 1 Red Blue/White

Tip 2 Black White/Orange

Ring 2 Yellow Orange/White

Multiple jacks in a residence

Plenum versus non plenum cablingWhyCharacteristics

Cable SpecificationsReview specs on a given cable – look up on

webhttp://docs.commscope.com/Public/5504LC.p

df

NEXT – Near end cross talk or EMI, signal transmitted on an adjacent pair from the near end and measured at the near end

FEXT – Far end cross talk, signal transmitted on an adjacent pair from the near end and measured at the far end of the cable

Attenuation This is the decrease in signal strength (expressed as negative dB) from one end of a cable to the other. The main causes of attenuation are impedance, temperature, skin effect and dielectric loss. Impedance is the combination of resistance, inductance and capacitance in a cable, it is measured in Ohms and opposes the flow of current.

DC loop resistance

This is simply the resistance between the two conductors of a twisted pair which is looped back at the far end. The primary purpose of this test is to make sure that there are no high resistance connections in the link.

Return Loss When a cable is manufactured there are slight imperfections in the copper. These imperfections all contribute to the Structural Return Loss (SRL) measurement because each one causes an impedance mismatch which adds to the cables attenuation.

Delay This is the propagation delay or the time it takes for the signal to travel from one end of the cable to the other

Delay Skew

The difference between the fastest and slowest pairs. Some networks use a four pair transmission method, this means that the signal is split into four, sent down the four pairs in the cable and re-combined at the far end. It is essential that the signals reach the far end at near enough the same time, otherwise the signal will not be re-combined correctly.

ACR

The pink area in the graph is the attenuation, and the blue area is the crosstalk.

ACR

The first thing to understand about testing data cables is the ACR, this stands for Attenuation to Crosstalk Ratio. The pink area in the graph is the attenuation, this can be caused by several things as will be explained below, and the blue area is the crosstalk. Attenuation is the reduction in signal strength over the length of the cable and frequency range

the crosstalk is the external noise that is introduced into the cable. So, if the two areas meet, the data signal will be lost because the crosstalk noise will be at the same level as the attenuated signal.

ACR is the most important result when testing a link because it represents the overall performance of the cable.

Toning out a cableTest Equipment Demo –click on imageGeneratorReceiver

Basic Telephone serviceSignals on a telephone line

Tracing a line, another set of test equipment

BatteryRingDial tone