“Cumulative Leakage Index”What? Why? Who? Where? When? And How?

Listen for answers to these questions…What is CLI? Why do I need to be concerned with CLI?  FCC ---who are they and why are they involved?  Why keep leakage logs? What’s a microvolt?  What is noise and how can it impact customers?  Is there a direct correlation between CLI and

other distortions? Why is the customer's home a major contributor

to system problems?  Why is proper cable and connector craftsmanship

so important?

What is Leakage?*Cumulative Leakage Index (CLI)CLI is the net effect of the combination of all

the leaks in the system added together =the amount of radio frequency (RF) signal that escapes or infects the cable system

These cumulative leaks form an invisible cloud of unwanted RF energy over the cable system

Leakage results from:Improper cable installationcomponent corrosionpoor product designVandalismcable breakspoor connections

Two types of leakage: Egress and IngressEgress= RF signal leaking out of the cable system

Damaged cableImproperly installed cableSignal escapes and follows the path of least resistance

including free space (air), strand, power and phone linesIngress= RF noise or interference that leaks into the

cable system through a break or external leak (loose connectors)Hair dryers, microwaves, radios, etc.Feeds into the coax drop from bad TV’s, long center

conductors, amplifiers, jumpers, customer equipment (VCR)

Ingress/EgressIngress:RF signal leaking into the coaxial plant

Egress:RF signal leaking out of the coaxial plant

Why Is It Important to Determine Leakage?Cable television systems and licensed over-the-

air broadcasters use many of the same frequencies to transmit programming. Specifically, cable systems use TV, radio and aeronautical radio channels, among others, within their cable plant.

Cable operators are considered the secondary users of these frequencies; therefore they must not interfere with the licensed over-the-air users who are the protected (primary) users of these frequencies.

What Problems Can Signal Leakage Cause? Cable signal leakage can interfere with any of

the over-the-air services that happen to be using the same frequencies as the cable operator and that are within the vicinity of the cable system.

Such interference, especially on the emergency channels, can interfere with the communications of safety personnel or airplane pilots.

When such interference occurs, it can endanger the lives or hamper the rescue efforts of safety personnel.

What are the FCC Rules Governing Signal Leakage? The FCC (Federal Communication Commission)has

set maximum individual signal leakage levels for cable systems.

The FCC sets even more stringent limits for cable systems that may interfere with aeronautical and navigation communications.

As a further measure, the FCC requires cable operators to have a periodic, on-going program to inspect, locate and repair leaks on their systems. –FCC files include:CLI quarterly ride outs (100% of system & log all leaks)Annual Flyovers (report on form 320)Daily Leakage Logs (date found/date repaired)

Can the Cable Company be penalized if it fails to control CLI?

4/17/2012

Pays to keep the system clean… In this Notice of Apparent Liability for Forfeiture (NAL), we

find that Cebridge Acquisition, LP (Cebridge), operator of the cable television system in Honey Grove, Texas, apparently willfully violated Sections 76.605(a)(12) and 76.611(a)(1) of the Commission’s rules (Rules),[1] by failing to prevent excessive signal leakage in the Honey Grove cable system.  We conclude that Cebridge is apparently liable for a forfeiture in the amount of eight thousand dollars ($8,000). 

Quarterly CLI Drive Out Results

Unauthorized Connection 1333 44.7%

Loose F Connector 426 14.3%

Loose Terminator 185 6.2%

Replace Connector 142 4.8%

No Fault Found 415 13.9%

It is a shared responsibility across Operations and Engineering.

Five Steps in Leakage AbatementDetectionLocationMeasurementCorrectionRe-measurement

Detection (What do I need?)Carrier Generator- a unique frequency

inserted by the headend that can be recognized by the leakage detector tuned to the carrier’s frequency

Leakage Detector- (Seekers’, Searchers’, Sleuths’)-provided and used by all technicians to detect leaks in the free space where RF energy is encountered

Calibrating Leakage Equipment1.Connect calibrated signal source set at 20 uV/m.2. Position the dipole antenna.3. Adjust to read 20 uV/m.

Identify the precise Location of the leak with your Leakage Detector

Hand Held Detectors Check the battery voltage, insure the unit is

charged before you proceed to isolate the leakListen to the audible alarm indicator as you

proceed to isolate the leak sourceIncreases in the tone pitch indicate you are closer

to the sourceDecreases in the tone pitch indicate you are

moving away from the leak sourceFollow the manufacturers recommended mode to

identify the leak sourceOnce the leak is identified to a pole, cable, or a

home, follow standard troubleshooting procedures until the leak is within compliance

Measurement-rules of engagementOnce a leak is located it must be

measuredμV/M What is a microvolt per Meter?

Standard unit of measure for CLI 50 Ohm off air measurementVoltage developed in 1 meter of infinitely thin

section of wire submerged in a leakage field produces 1μV of energy

All leaks greater than 20 microvolt's MUST be repaired per FCC rules

Any leak greater than 50 microvolt's MUST be repaired IMMEDIATELY per FCC rules

Measurement-rules of engagement (cont.)

Only leaks above 50 μV/m are used in CLI calculation

All measurements taken outside 108-137 MHz must be converted as if they were taken within the band

Leakage Detector-measures the level of the leak Take the reading at about 10 feet (3 meters)Repair itRe-measure

Measurement-rules of engagement (cont.)

Use a calibrated halfwave dipole antennaAntenna must be elevated 3 meters off the

ground and positioned 3 meters from the leakage source

Antenna must be rotated 360º in the horizontal plane for maximum reading

Turn on your Leakage Detector!

Measurement-Why do we care?

1. Meet FCC Compliance2. Prevent Off-Air Interference

Aeronautical & Aircraft CommunicationsAmateur Communications Broadcast TV signals (Analog & Digital)Public and Emergency Communications Radio Mobile Communications

Measurement-Why do we care?

3. Improves System PerformanceReduces Repeat Service CallsLocate Physical problems

Correction of Leak80% of all leakage is caused by problems

from the tap to customer equipment Common Causes of Leakage-

Loose drop connectorsImproperly installed connectors Inferior quality coaxial cable, passives, or

connectorsPoorly-shielded drop cablesBad connectors at the tapsBad/loose port terminators Corroded connectors

CorrectionCommon Causes of Leakage-cont.Cracks in the trunk and feeder cablesAnimal chews Physical trauma to cables or connectorsAging and environmental stressLoose hard line connectors

CorrectionCommon Causes of Leakage-cont.Customer installed equipmentDamaged amplifier housingsLoose amplifier housing lidsBroken tap portsPoor installation of splices and connectors Poorly-shielded customer premise equipment

Ingress impacts on Digital ChannelsMacro Blocking (Tiling)Freeze FramePicture and Sound go to blackRobotic VoiceData Packet Loss or slower speedsRepeat Service Calls

Ingress impacts on Analog ChannelsLines in pictureGhostingPay-per-view problemsInterference with two-way radio services

using the same frequenciesRepeat Service Calls

CorrectionRepair the leak- determine the root cause and

use TWC procedures to implement proper restorationTighten or replace connectorsReplace cracked or damaged cableTerminate open ports with 75 ohm terminatorsCorrect customer created issues (replace

splitters, self-run inferior cable)Properly terminate unauthorized connections

and report theft of service to Audit/Security operations

Audit/Security ProcessInsert your local process and contact

information

Re-measurementTake a final reading using the same

equipment and record the corrected CLI calculation (reportable to the FCC)

If the leak is still above 20 microvolt's it is NOT repaired (incomplete diagnosis-reengage)

Work the issue backtracking all the cable and connections

Correct issue until leak is under 20 microvolt's

CLI tipsTurn on your CLI equipment and use

properlyRecord/Repair/Re-measure your leaksTighten all connectorsUse PPC Signal Tight Connectors indoorsProperly terminate open portsDisconnect unauthorized drops and properly

terminate

EX vs EX PLUS G2 Comparative.wmv

Benefits of CLI programReduced ingress/noise in the plant (SNR)Increased plant performance (FEC)Better CPE performance thus improved

Whole House CheckReduction in Trouble Calls (TC to RGU

and rework)Customer Satisfaction!

Be careful using the word “radiate.”

(Q & A’s from the FCC website)

FAQ’s from the customerDoes a Cable Operator Need to Come into My

Home to Monitor for Signal Leakage?Usually, no. Cable operators can use equipment to

locate the general area of a leak. To pinpoint a leakage source for subsequent repair, however, the cable operator may request access to your home.

Am I Required to Let the Cable Operator into My Home to Monitor for and Repair Signal Leakage? Homeowners have the right to deny access to their

premises. If a leak cannot be repaired without access to your home, however, a cable operator can disconnect your service for denied access.

FAQ’s from the customer (cont.)Can My Cable Operator Terminate My Service

Because of Signal Leakage? The FCC’s rules allow cable operators to

disconnect service in order to repair signal leakage that exceeds FCC standards. The operator restores service when the signal leakage problem is remedied, and may not charge you for service while it is disconnected.

Is the Cable Operator Responsible for Repairing Signal Leakage on Subscriber-owned Equipment? No.

FAQ’s from the customer (cont.)Can I Hook Up a Second Set Myself?

In terms of the signal leakage rules, yes, but because the cable operator is responsible for leakage from the wiring, the operator can either refuse to connect to it or terminate service if the hook up causes signal leakage problems.

Is Signal Leakage Biologically Harmful? The power levels used in a cable system are

low. Therefore, it is unlikely that cable signal leakage from a cable facility will exceed the FCC’s RF allowable limits for RF exposure.

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