Presentation on theme: "Technical Training Seminar on “Egress & Ingress Testing and Troubleshooting” for CCTA Member Companies August 25, 26 and 27, 2009 San Juan, Puerto."— Presentation transcript:
1 Technical Training Seminar on “Egress & Ingress Testing and Troubleshooting” for CCTA Member Companies August 25, 26 and 27, 2009 San Juan, Puerto RicoMario SebastianiTony Holmes
2 Seminar SummaryHow the Egress and Ingress of unwanted signals in the forward and reverse plant behaveHow they effect picture, data and voice qualityWhat to look for and how to fix it
3 Technical Training Outline Egress terminologyWhat is egressWhy do we test for egressWhat causes egressEgress characteristicsLocating source of egressSignal Egress/Leakage AutomationThe specific chapters of this seminar areLeakage terminology- I will go over various terms commonly used with regard to signal leakageWhat is leakage- I will define leakage and try to create a mental picture of signal leakageWhy do we monitor for leakage- I will discuss the 4 basic reasons for monitoring leakageWhat causes leakage- I will mention some of the common and unusual causes of leakageLeakage characteristics- I will explain why leakage acts the way it does
4 Egress Terminology Leakage Radiation (Never Say!!!) µV/M Squelch CalibrationTagging (CT-2 or CT-3)Egress - Older term used among RF engineers- Term still used in other industriesRadiation - Original CATV term- Not advisable term around customersLeakage - Fairly recent term which best describes the nature of the problemIngress - Opposite of leakage- Signal leaking “into” the cable systemuV/M - Microvolts per meter-.Preferred unit of measure by the FCC- Leakage measurements are in the same units of measure as radio transmissionSquelch - Adjustment to leakage detector determining the leakage amplitude necessary to set off audible alarmof a leakage detectorCalibration - Adjustment to leakage detector to assure accurate level reading of leakage
5 What is Egress/Leakage? Definition:Undesired emission of signals out of HFC networksEgress is generally referred to as signal leakageWhat is signal leakage?The undesired emission of signal out of an HFC network.We monitor a specific frequency for signal leakageHowever:1.) If you leak one you are leaking all frequencies2.) All frequencies do not leak at the same amplitude.3.) Leaks become worse over time.4.) Leakage is evasive, measurements taken at the same location at different times do not always produce the same readings.We will discuss how leakage can be:Dangerous - to aero-navigational usersDisruptive - to off-air broadcastersDestructive - to the physical condition of the plant if left unrepaired
6 Egress & Ingress Egress Ingress RF signal leaking out of the coaxial environmentIngressRF or electrical energy that enters the coaxial environment
7 Why do we test for leakage? Why do we monitor for leakage?4 Primary reasons
8 Reason #1 to Test for Leakage Meet FCC Compliance
9 Spectrum Chart 108MHz 137MHz Aircraft Radio & Navigation CH 98 CH 99 Off-airCableBroadband communication networks are designed to be closed system networks. Since Signals in these networks are theoretically “contained” and not exposed to the “off-air” environment, all frequencies then become available for the network operators’ use.The problem arises when signals leak out of these networks and interfere with off-air users of the same frequencies.TVAircraftLand mobileGovernment communications
10 Cumulative Leakage Index (CLI) CLI is the net effect of the combination of all the leaks in the system added togetherThese cumulative leaks form an invisible cloud of unwanted RF energy over the cable systemCompliance = 64 or less
11 CLI Quarterly Rules Ride out 100% of system and log all leaks Log should include Date found and Date fixedDocumenting leakage levels isn’t required for this drive outActual practice for your system may vary!
12 CLI Annual RulesRide out 75% of the oldest part of the system and log all leaks location and measured levelMust be performed within a reasonable period of timeUsually within 2 wks of due date
13 Required Actions All leaks 20µV/m must be logged and fixed Only leaks above 50 μV/m are used in CLI calculationAll measurements taken outside MHz must be converted as if they were taken within the band
14 μV/M Standard unit of measure for CLI 50 Ohm off air measurement Voltage developed in 1 meter of infinitely thin section of wire submerged in a leakage field produces 1µV of energy
15 Acceptable Procedures for Leakage Measurement Use a calibrated halfwave dipole antennaAntenna must be elevated 3 meters off the ground and positioned 3 meters from the leakage sourceAntenna must be rotated 360º in the horizontal plane for maximum readingCLI Fly-over
16 Reason #2 to Test for Leakage Prevent Off-Air Interference
17 Off-Air Interference Aeronautical & Aircraft Communications Amateur CommunicationsBroadcast TV signals (Analog & Digital)Public and Emergency CommunicationsRadio Mobile Communications
18 Off-Air Spectrum (forward path) 300400500900700800Frequency in MHzSource: NTIA
19 Reason #3 to Test for Leakage Improves System PerformanceReduces Repeat Service CallsLocate Physical problems
20 Common Causes70% of all leakage is caused by problems between the tap and entry to the houseAging and environmental stressPhysical trauma to cables or connectorsLoose drop connectorsInferior quality coaxial cable, passives, or connectorsLoose hard line connectorsCommon causes:- cracks in cable- corroded or loose connectors- loose device enclosures
21 Other Causes of Leakage Improperly installed connectorsCracks in the trunk and feeder cablesAnimal chewsPoorly-shielded drop cablesBad connectors at the tapsBad/loose port terminatorsCorroded connectorsUnusual causes:- squirrel chewing on hardline coax- dog chewing RG coax- puncture in coax at midspan locationsclamps without the use of spacerstree branch rubbing or falling on cableprojectiles - gunshots, arrows, pellets, etc.vandalism- customer caused leakageuse of antenna on A/B switchillegal outlets using inferior materialstampering with settop box
22 Other Causes Continued Customer installed equipmentDamaged amplifier housingsLoose amplifier housing lidsBroken tap portsPoor installation of splices and connectorsPoorly-shielded customer premise equipment
23 Polarization Angle Dipole MonopoleDipoleLeakage signals are normally at their highest amplitude in the horizontal plane. This is probably due to the fact that most of the cable plant is in a horizontal position.The FCC requires the use of a horizontal dipole antenna to make CLI compliance measurements. This would be to optimize the leakage signal reading by matching the polarization plane. However, it is required to rotate the dipole antenna to match the polarization angle for peak amplitude readings.For “Find and Fix” maintenance purposes, a vertical whip antenna is preferred because of its omni-directional properties vs. the directional properties of a dipole. Peaking a dipole antenna on a moving vehicle would be impractical.With a handheld leakage detector, you would be rotating the “rubber duck” antenna from a vertical to horizontal plane, looking to maximize the peak amplitude reading and determine the direction and ultimately the location of a leak.
26 Signal phasing Radiated signals can: 1.) Reflect off surfaces ` 2.) Travel on conductive surfaces3.) Occur from more than one nearby locationThese “Multipath” signals arrive at the leakage receiver at different times but at the same frequency.These multipath signals can combine inside the leakage receiver and cause a time relationship problem which may add to or cancel from the signal amplitude reading, depending on the phase relationship.Being aware of potential multipath conditions is the only thing a technician can do. Awareness of such condition would encourage the technician make extra effort in properly peaking the antenna.
27 Standing WavesAs stated before, leakage signals can travel down a conductive path to ground.In most cases this conductive path will be the strand wire or the coaxial sheath.The technician should continue monitoring a leak until a peak reading is made.
28 Electrical NoiseElectrical noise is an interesting annoyance to the leakage technician.In most cases, electrical noise is caused by “spark gap energy” at power line insulators. This energy can manifest itself as RF!This spark gap energy (RF) may reach the leakage frequency range and cause a buzzing noise on the audio circuit of a leakage detector.Channel tagging usually eliminates this problem.
29 Leakage Field Strength AmpLowestPotentialConsider an amplifier the transmitter....Consider leakage points along the cable as antennas....Result: The antennas closest to the transmitter have the highest potential for power.Leakage amplitude is determined by:- the available signal level in the coax at the point of leakage.- the severity of the physical condition causing the leak.HighestPotential
30 Distance Correction Reading x Distance (meters) = Corrected Reading3Why would you want to know the leakage level from a 10 foot distance?The FCC states:Leaks greater than 20uV/m at 10 feet shall be logged and then repaired within a reasonable period of time.Note the measurement reference is at a 10 foot distance from the plant.This distance correction formula will aid in determining the repair priority of a leak.At this point it would be well to note that many operating companies commonly have more stringent requirements than the FCC.
31 Patrolling for Leakage 3 meters20µVm30 metersPinpointing sources of leakage can at times seem to be more of an art than a science.Patrolling the system: The first indication of leakage will be very short tone pulses from the leakage receiver. These will be followed by longer pulses eventually changing to a continuous tone if the leakage is strong enough. Relying solely on the audio indication, drive the vehicle until the tone starts to decay. Mentally mark the peak tone indication and return to that area for further investigation. Note: best result at at patrolling speeds of under 25 MPH.Apply distance correction formula: This will help determine the priority of the leakage repair.2 μVm
32 Walking Out a Leakage Area Walking the area: Use the rubber duck antenna or near-field probe to find the exact source of the leakage. The near-field probe is especially useful in congested mechanical areas, such as multi-connector housings and MDU locations.If the leakage amplitude is greater than the threshold setting on the leakage detector, an audible tone will sound from the detector.Listen for the audible pitch of the leakage detector to rise from the increasing signal amplitude as you get closer to the leakage source.Optional: In areas where it is difficult to determine the direction of a leak, the technician can use a dipole antenna to triangulate the leakage source.If necessary, use the near-field probe to literally touch suspected points of leakage. When many connectors are within close proximity of each other, using the near-field probe will help determine which connector(s) is the cause of leakage.5 – 10 meters
36 Seeker GPS System LAW Client Serial GPS Rx Bluetooth GPS Rx Seeker LAW The Seeker GPS System expands the Seeker into full GPS and map-based leakage management system, covering all activities from leak discovery to resolution, from data collection to map graphics, reports and analysis.When the MCA is communicating to the GPS receiver the blue LED will blink approx twice per second if not it blinks once per second.Connecting MCA to Seeker Setup:1. Load Seeker Setup software then install USB drivers2. Connect the MCA via the mini- USB to USB cable to PC. First, get Setup from MCA then Search for Devices then Send Setup to MCALAWServerMCABB-2
37 Seeker GPSData Storage GPS Equipped WiFi Upload Capable MapQuest Mapping Server Based
38 Driving Preparation GPS This icon is shown when the Seeker is placed in the mobile mount and a GPS connection is established with the MCA. When the icon is not shown, the Seeker is not in the mobile mount or the GPS connection cannot be established with the MCA. If the icon blinks the MCA is connected to the GPS but the GPS does not have a good position fix
39 Records uploaded to client Seeker Data PathsLeak ReadingsFrom GPSRecordsOther ApplicationsWIFIPort 24007Records uploaded to clientLawServerPort 80Third PartySoftware
40 Work Order Distribution As leaks are uncovered, work orders will be assignedto technicians assigned to a specific leakage territoryor to the supervisor responsible for the areaWork order sent to designated person viaTechs can act on a leak reported via , take the appropriate pre- and post-fix snapshots, upload the data in the usual manner and the work orders will then close themselves out as the leaks are repairedEven the assignment of work orders can be automated. In this mode of operation, as leaks are uncovered, work orders will be assigned either to technicians who are designated in the application as responsible for a specific leakage territory, or perhaps to the supervisor responsible for the area. The designated person will be sent the work order via . In this way, technicians can act on a leak reported via , take the appropriate pre- and post-fix snapshots, upload the data in the usual automated manner and the work orders will then close themselves out as the leaks are repaired. In the fully automated method of working, the only supervisor intervention required will be for the FCC filing requirement.
41 LAW Map Versatile Map Interface Sort-able Leak List The LAW map works like most familiar Internet map web sites, in that the user can click and drag to move the map within the window, double click to center, mouse over pinpoints to bring up further data, and click the pinpoint to get complete details.The data list below the map can be sorted by any of the columns, and the supervisor can check mark specific leaks by clicking on the associated box, and then create a work order by clicking the “Create Work Order” button.(The plant manager can sort the detected/mapped leaks by field strength in an associated table on the map page, and assign work orders logistically. )Simple Work Order Generation
42 Aerial ImageThe ability to switch to a hybrid aerial image and map gives some insight into the physical features of the location, helping the tech to be more prepared for the work, and possibly speeding the leak repair.
43 Work Order Distribution Even the assignment of work orders can be automated. In this mode of operation, as leaks are uncovered, work orders will be assigned either to technicians who are designated in the application as responsible for a specific leakage territory, or perhaps to the supervisor responsible for the area. The designated person will be sent the work order via . In this way, technicians can act on a leak reported via , take the appropriate pre- and post-fix snapshots, upload the data in the usual automated manner and the work orders will then close themselves out as the leaks are repaired. In the fully automated method of working, the only supervisor intervention required will be for the FCC filing requirement.
44 Pre and Post-Fix Measurements Snapshot ModeUse the Seeker’s Snapshot button to access the snapshot modeIn the less automated part of the process (that dictated by the FCC procedure) the leakage tech makes a peak measurement of the leak with a dipole antenna (10 feet from the leak and 10 feet from the ground). The meter’s “snapshot” button makes capturing the peak level simple. The pre-fix measurement snapshot is automatically logged and recorded in the database when the stored measurement data is uploaded. The post-fix measurement snapshot automatically closes out the work order and eliminates that leakage flag (push pin) from the map. Through this process the leakage map in LAW has become a virtual real-time representation of the leakage condition of the cable plant.
46 Reason #4 to improve system quality Eliminates forward and return IngressPrepares network for triple play deploymentsTo increase plant performance and reliability
47 Ingress There is a direct relationship between Leakage and Ingress If signals can leak out of your system, off-air signals can leak into your system.The degree of ingress is determined by Signal leakage amplitude vs Off-air signal amplitude.
48 Ingress on Analog Channels Lines in pictureGhostingPay-per-view problemsHigh speed data problemsInterference with two-way radio services using the same frequenciesRepeat Service CallsInterference to a customer’s analog pictures can be identified as:Ghosting or black vertical bars in the TV picture. This occurs when the same program on the same channel is ingressing into the cable or TV set.“S” shaped or diagonal lines in the TV picture. This occurs when a different program on the same channel is ingressing into the cable or TV set.Intermittent lines in the picture and possibly audio buzz. Possible causes are:- CB radio effecting channel 5- Local pager services effecting channels 19 & 20- Ham radio effecting 5-40 MHz return band and MHz band
49 Ingress on Digital Channels Macro Blocking (Tiling)Freeze FramePicture and Sound go to blackRobotic VoiceData Packet Loss or slower speedsRepeat Service CallsInterference to a customer’s digital pictures can be identified as:Mosaic - This happens when ingress has created marginal Bit Error causing the loss of a packet(s) of video compression dataFreeze frame - This happens when ingress has created significant Bit Error causing the loss of an entire refresh frameLoss of picture and sound to black - This happens when ingress is severe enough to completely destroy a data stream into unusable garbage.
50 Increased implementation of services requiring return path activation If a system has egress it will most likely have ingressIngress brings the viability of two-way services into questionVoIP demands higher network reliability49898
51 Forward and Return Ingress Troubleshooting Tools
52 QAM EVSTroubleshooting in-channel ingress is easy with the QAM EVS modeTypical ingress areasLoose connectorTap plate looseHome wiringSometimesCSO/CTB from an over driven amplifierThe Trilithic 860DSPi has a unique feature that allows the user to see ingress or other interference under a 64- or 256-QAM digitally modulated signal without turning the carrier off. The meter mathematically removes the haystack from the display, allowing the noise floor under the signal to be seen.In this example, the QAM analyzer’s ‘Peak’ marker is auto placed on a beat -30.1dB 0.251MHz above the digitally modulated signal’s center frequency.Troubleshooting in-channel ingress is easy with the QAM EVS modeTypical problems: Ingress from of air UHF channels caused by: Loose connectors, Tap plates loose, Home wiringExample: In-channel carrier-to-interference ratio of -30.1dB MHz above center frequency
53 Constellation Good MER Poor MER Constellation screen The constellation screen gives a visual indication of how far the noise is moving the signal from its ideal locations on the constellation.Problems:Low signal levelHigh noise floorGood MERPoor MER
54 BER Digital signals work well until very close to the point of failure Measurement of digital carriers critical to determine the system marginSignal levelMERBERThe BER Mode helps to find problemsDigital signals work well until very close to the point of failureMeasurement of digital carriers critical to determine the system marginSignal levelMERBERThe BER Mode helps to find problems
55 DemonstrationInterferences from VHF/UHF sources
60 Ingress Mitigation Test This is a test where you can quickly check thedrop and home wiring for ingressSet Ref level so as to not over-loadthe meterDetector set for averagingRBW at 300 KHz10 db/divSpectrum MHzUse peak holdSet up the Analyzer so you see what you want to see, ingress.The reference level is set dependant on where the tech is located in the network (ground block, tap seizer screw, amp, etc…). What you don’t want is to set this ref level to low and over-load the front end of the meter which can cause spurious beats that don’t exist.Detector setting on averaging so you can control the amount of averages (“digital snap-shots”) during the sweep scan.Resolution Bandwidth setting at 300 KHz because this is what most spectrum analyzers have. If your fortunate to have a meter that you can adjust the RBW then try setting it lower like 100 KHz this will help with smoothing out the noise that you know is supposed to be there.10 db/per division so you can see as much as possible at first.Spectrum bandwidth so you can see all of the return, plus the FM band. We (being the MSO) used to provide FM off-air signals across our network. There by a customer could connect his FM receiver up to the plant and receive quality FM signals to his stereo equipment.We long since abandoned this service (DMX is so much better!) but some customers still have their FM tuners still connected to the home wiring. So being able to “look” at the FM band we can quickly see unwanted signals.Use of the peak hold function will aid in seeing bursty and intermittent carriers that are there one second and gone the next.
61 Ingress Mitigation Test What you should see is NOTHING!Just the noise floor
62 Ingress Mitigation Test Look for ingressby using the“Peak Hold” functionIdentify the problem by workingback towards the houseStarting at the tap connect the drop to your meter and watch for ingress.If you see some work back towards the home and through the process of elimination you can dial in on the ingress and where it’s originating at.
64 Using the I-Stop Probe Press the button on the side of the probe If the ingress decreases by 4-6 dB when the button is depressed, the source of the ingress is farther from the node than you areIngress that doesn't decrease is entering the system nearer to the node than you are. The I-Stop Probe has little or no visible effect on forward path signals.
67 Monitoring Thresholds Alarm threshold information is stored in the 9581 SSTFive degrees of severityFor Ingress levelsCritical to WarningFor OutagesNo Signal WarningPersistence SettingsAuthenticate alarm conditionsTraffic CurveIdentifies the frequency and amplitude of carrier
68 Viewer II User Interface ComponentsStatus TreeIncident LogAlarm HistoryNode ReportingSpectrum DisplayADIA Web View
69 Node Status Tree Geography Services Groups nodes by City Headend HubsiteServicesCMTSBlade
70 Incident Log Displays Current Node Alarm Events based on SNMP Traps received by the Guardian II ServerTraps Originate in the 9581 SST based onAlarm Threshold ViolationsPersistence SettingsDisplayed information is based on Status Tree Configuration, but typically includesNode IDSeverityElapsed TimeTotal Alarm Time
71 Alarm Management Prioritize Alarm Information Sorting Tools Organize alarm information into logical groupings for managing service interruptions
72 Alarm Troubleshooting To investigate alarm conditions NOC operators can click on alarm events in the incident logBrings up Spectrum view withAlarm threshold and ingress signature that caused the alarm eventAllows operator to correlate alarm data from other monitoring sourcesEvaluate the effect of ingress on system services
73 Reporting Node Service Report Returns Alarm Activity over user specified time periods and locationsProvides correlation of service interruptions and return path ingress eventsIdentifies and prioritizes nodes in need of maintenanceSelection CriteriaAlarm severityNumber of nodes per location
74 Node Service Report Summary View Includes selection criteria Lists nodes meeting selection criteriaGrouped by locationNumber of nodes per location or top X nodesNumber of alarm events per location
75 Spectrum DisplayViewMax/Min/Avg ingress spectra over reporting periodPass/Fail ThresholdPass/Fail ToleranceRatio (dB) between threshold & ingress spectra
76 ADIA Web View Real time access to headend ingress levels Max/Min/Avg TracesMarkers withFrequencyAmplitudeDelta
77 Demonstration Impairments from : Digital TV Transmitters Return Path Ingress
78 Response to Your Question!!!! s Now let me address the questions that were sent…78
79 Thank you-Gracias-Merci-Masha danki… Trilithic Applications EngineeringTel:Incospec Communications Inc.Your Value Adder Trilithic Re-Seller for the CaribbeanMario SebastianiBernard How
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