Tony Holmes Technical Training Seminar on

Tony Holmes Technical Training Seminar on
“Identifying Picture Problems in a HFC Network” for CCTA Member Companies August 12, 2008 St. Kitts August 15, 2008 San Juan Mario Sebastiani Tony Holmes

Detailed Agenda Visual Carrier Levels Aural Carrier Levels
Adjacent Visual Carrier Levels Carrier to Composite Noise (C/N) Coherent Disturbances (C/I, CSO, CTB) Hum Modulation Digital Channel Power MER measurements & BER behavior Leakage and Ingress behavior Depth of Video and Audio Modulation

Problems Simulator Suitcase

Carrier Level Measurements

In This Section You Will Learn
Why carrier levels are important How to accurately measure carrier levels with a spectrum analyzer Differences between a spectrum analyzer and a signal level meter

Why Measure Visual Carrier Levels?
The FCC Says So! Subscriber satisfaction Critical for other system performance

Visual Carrier Level FCC 76.605 (a) (3)
Specification: 0 dBmV at subscriber terminal Picture effect: Snow on picture as if poor carrier-to-noise level Spectrum Analyzer Spec: ± 1.0 dB Number of Test Points: 6+ Number of Channels 4+ Frequency of Test Two times per year Location of Test: Subscriber terminal and head end Center Frequency Span Resolution BW Video BW Sweep Time Reference Level Scale Center on visual carrier 6 MHz 300 kHz Auto Higher than carrier 10 dB/div Spectrum Analyzer Settings Measurement Notes: None

Aural Carrier Level FCC 76.605 (a) (5)
Specification: 10 to 17 dB below visual carrier Picture effect: Muffled sound, next channel visual modulated by sound Spectrum Analyzer Spec: ± 1.0 dB Number of Test Points: 6+ Number of Channels ALL NTS Frequency of Test Two times per year Location of Test: Subscriber terminal and head end Center Frequency Span Resolution BW Video BW Sweep Time Reference Level Scale Center on carrier 6 MHz 300 kHz Auto Higher than carrier 10 dB/div Spectrum Analyzer Settings Measurement Notes: Use two markers

Relative and Absolute Amplitudes
Relative Frequency, Hz Absolute Frequency, Hz Absolute Amplitude, dBmV Relative Amplitude dB Absolute levels only on visual carrier All other amplitudes relative to the visual carrier

Resolution and Video Bandwidths
Resolution BW must be wide enough to "see" picture pulses but narrow enough not to see adjacent signal Video BW must be as wide or wider than resolution bandwidth Screen dump needed

Levels of Suppressed Sync Scrambled Channels
Don't change the resolution bandwidth Make the signal stay in the IF bandwidth longer by lengthening the sweep time Enhance the peak detection by using Trace Maximum Hold

Overload Causes Inaccuracy
Linear Operation Non-Linear 0.5 dB Decrease In Mixer Output Power Total Power Into Mixer, dBmV Power From Mixer At IF, dBmV Gain Compression Power, dBmV High input can cause low readings Compression Same on SLM???

Accuracy of Visual Carrier Level Reading
Better than ± 2 dB Self calibration Routine maintenance every two years

Adjacent Visual and Aural Carriers
> 10 dB < 3 dB > 13 dB Adjacent Visual Carriers Audio Sound carrier must be 10 to 17 dB down from picture carrier Visual and aural carrier measured with the same analyzer settings Measure their differences with both on-screen

Television Channel Frequencies
1.25 0.5 0.75 MHz min MHz 4.2 MHz 4.5 MHz 5 kHz 5.45 5.75 6 6 MHz 2 4 1.0 Relative Field Strength Picture Carrier Sound Carrier Video Bandwidth

Level Measurement Single Channel Display of
NTSC or PAL Video, Audio, SAP, Amplitude Function Key: “Goto” Full Scan… Channel Spectrum… or QAM Pull-down: Jump to data logging and other functions

Channel Tilt Up to 10 Pre-Selectable Tilt Channels
You can toggle the display with the Fn button Bar Graph Level Measurement Data Numeric Display The LOW and HIGH SOFTKEYS are used for computing the tilt

Full Channel Scan Scan Refresh Rate: > 1 Sec
Displays the amplitude of all Visual and Audio carriers in the selected channel plan. Choose between a simultaneous line graph (or) a bar graph Use the Fn button to quickly bring off scale signals on screen when viewing the Level Graph

Questions?

Problems Simulation (Levels)

Carrier-to-Composite Noise Measurements

Basic Measurement Principals
Swept Tuned Analyzer

Noise Power Measurement
frequency 4 MHz Filter Measured power Noise power contains all frequencies FCC requires noise measured in 4 MHz bandwidth Simulates the noise power received in a TV (4 MHz video bandwidth)

Measuring Power with a Spectrum Analyzer
The spectrum analyzer resolution filter acts as the noise filter It is not a square filter, so corrections must be made Another correction is made because the analyzer does not have a 4 MHz wide filter

Correcting Analyzer Noise Power Measurement
Use 30 kHz resolution bandwidth Add to the noise to correct for 4 MHz bandwidth Add 2.5 dB because the Spectrum Analyzer isn't a perfect voltmeter For Total Noise Correction add dB

Is It System Noise? Internal spectrum analyzer noise may be too high to allow system noise measurement  use the disconnect test

The Disconnect Test If > 10 dB drop, no corrections needed
Noise-Near-Noise Correction (dB) Noise Drop For Disconnect Test, dB 1 2 3 4 5 6 7 8 9 10 If > 10 dB drop, no corrections needed If > 3 dB drop, correct by using the graph below If < 3 dB drop, use a dB gain, <10 dB noise figure preamplifier When using a preamp it may be necessary to also use a bandpass filter. If the noise floor increases more than the gain of the preamp then the preamp is causing distortion or ‘noise floor lift’.

Correcting Analyzer for Noise-Near-Noise
0.5 dB 1.2 dB 3.0 dB 6.9 dB 10.0 dB 6.0 dB 1.0 dB (a) Disconnect Test (b) Correction Values System Noise Analyzer This is a graphical representation of the previous slide to illustrate the correction factor. Noise contributions from the analyzer

Summary of Analyzer Corrections
For voltmeter and bandwidth: Add dB For disconnect test: Subtract the value on graph Preamplifier correction

Quick CCN Measurement Measure the carrier peak in 300 kHz resolution and video bandwidths Set the bandwidth to 30 kHz Set video bandwidth to 100 Hz Measure noise 1.2 MHz below the picture carrier Disconnect test

Results Are Worst Case Carrier is 36 dBmV Noise is -37.58 dBmV
Add dB Disconnect 6 dB drop (Subtract 1 dB) Noise = dBmV Carrier/ Noise = dB/4 MHz

FCC CCN Measurement Requirements
Video modulation off Measure within video frequency range FCC C/N range

Automatic C/N Measurement
Gated analyzer measures modulated carrier in video range No subscriber interference Corrections made automatically Preamplifier added if required Overload avoided The gated CCN is a worst case result. It includes noise from the video source. Operators are only responsible for noise they add so if the result is close to the FCC limit then you should test noise with modulation and or carrier off to get the noise contributed by your system.

Test Choices and Accuracy Assessment
Quick test between Channels FCC Test (with and without modulation)

CCN Test has Built-in Accuracy Evaluation

8821Q CCN Measurement Measure C/N
Check analyzer noise correction value in results box on screen - 3 to - 8 dB 0 to - 3 dB Using BPF Done Add BPF If best accuracy is desired use a bandpass filter Add external amplifier or test at a higher level test point YES NO

Manual CCN with Spectrum Analyzer
Measure C/N Noise floor drop during disconnect test Drop > 10 dB Calculate Correction Factor Done Drop < 3 dB 3 dB< Drop < 10 dB Zero dB Noise drop Add BPF Add Preamp If not overload, then decrease ATTEN 1 step Decrease Analyzer Attenuation 1 step YES NO Not 0dB The manual measurement of carrier to composite noise is difficult, time consuming and prone to errors in the calculations. Yes

CATV Analyzer CCN Accuracy
CCN Accuracy vs. Analyzer Noise Correction Correction Uncertainty ± 1 dB ± 2 dB ± 3.5 dB 1 dB 3 dB 7 dB } Results Good Improve Sensitivity

Carrier / Noise Measurement
Displays the ratio of the amplitudes of the visual and noise within a single selected channel The GO TO SOFTKEY gives a rapid access to the SPECTRUM and SCAN modes Use the Fn button to quickly bring off scale signals on screen when viewing the Level Graph

Carrier-to-Composite Noise Summary
Noise masks TV picture with snow Spec getting tougher Analyzer Measurement disconnect test correction for BW and voltmeter Manual measurement worst case Automatic measurement meets FCC rules

Questions?

Problems Simulation (C/N)

Analog Distortion Measurements

Coherent Disturbances FCC 76.605 (a) (8)
Specification: 51 dB Picture effect: Interfering line patterns, horizontal line streaks, various Spectrum Analyzer Spec: ± 1.5 dB to ± 4.0 dB Number of Test Points: 6+ Number of Channels 4+ Frequency of Test Two times per year Location of Test: Subscriber terminal and head end Center Frequency Span Resolution BW Video BW Sweep Time Reference Level Scale Center on carrier 6 MHz 300 kHz Auto Distortion above bottom div 10 dB/div Spectrum Analyzer Settings Measurement Notes: Carrier measurement same as carrier level, CSO ± 0.75 and ± 1.25 from picture, CTB at carrier. May need band pass filter

Sources of distortion How distortion appears on TV Coherent disturbances (C/I, CSO, CTB) What composite means Quick and practical tips Hands-on experience with manual and automatic measurements

Coherent Disturbances - Beating C/I,CSO and CTB
Additional signals in the cable frequency range Second order distortion - composite second order or CSO Third order distortion - composite triple beat or CTB From amplifier's non-linear behavior CSO from fiber, CTB from electrical amps.

Distortion Increases Through Each Amplifier
Frequency 2000 ft cable +21 dBmV +31 dBmV Amplifiers use gain to replace level lost through a length of cable. The unity gain concept. Unfortunately distortion (and noise) adds with each amplifier.

Why the Subscriber Complains about CSO/CTB Beats
Distortions cause a variety of visual effects CSO CTB CSO can appear as herringbone patterns (swimming diagonal stripes) and CTB can appear as horizontal streaks.

Composite Distortion The fewer the channels the less composite distortion Many distortion products fall on a single frequency The summation of these is called composite Composite beats are like a noise signal

CSO/CTB Measurement 53 dB Visual Carrier CTB CSO
Composite distortion is measured as dB down from the visual carrier 53 dB

FCC Compliance 51 dBc for non-coherent disturbances (Standard EIA Frequency Networks) 47 dBc for coherent Disturbances (Non-standard EIA Frequency Network)

Where They Fall For Standard frequency allocation systems
CTB CSO ±0.75 MHz ±1.25 MHz Visual Carrier Aural Carrier Lower Adjacent Aural For Standard frequency allocation systems CTB fall on the picture carriers CSO fall ±1.25 MHz and ±0.75 MHz from the picture carrier Channels five and six are offset from the rest of the carriers so the distortion products actually fall in the middle of the channel. Maybe add a slide with that screen dump to show they can measure CTB without turning off those channels.

Television Channel Frequencies
1.25 0.5 0.75 MHz min MHz 4.2 MHz 4.5 MHz 5 kHz 2 kHz 5.45 5.75 6 6 MHz 2 4 1.0 Relative Field Strength Picture Carrier Sound Carrier Video Bandwidth

CSO -1.25 MHz -0.75 Mhz +0.75Mhz +1.25Mhz

Practical Measurement Procedures
Measure CSO, CTB just like a CW signal Average the amplitude Treat low level signals like noise Correct as noise signal in CCN measurements Needs a line deleted to do the gated measurement in this example line 17 was selected but the line was not deleted.

Bandpass Filter (Optional)
Preventing Overload Tunable bandpass filter recommended Tunable Bandpass Filter (Optional) Preamplifier (optional) Spectrum Analyzer RF Input Cable Tap 2 dB Step Attenuator

Measurement Procedure
Measure carrier peak Turn off modulation Set 30 kHz resolution bandwidth Narrow video bandwidth to 100 Hz Composite level using marker CSO or CTB = visual carrier - distortion level Automatic cable analyzer can make the CSO measurement without interrupting the subscriber

CSO/CTB MODE Measures the amplitude of two common intermodulation products, Composite Second Order and Composite Triple Beat present within a selected analog video carrier Displays numerical values for CSO and CTB and a spectrum view You will need signal levels of at least 10 dBmv for proper measurements 860 DSP CSO CTB Measurement Composite Triple Beat (CTB) has Traditionally required the channel to be turned off because the disturbance is located below the carrier New devices have been produced to combat this problem. They can turn the channel off at a specified time for a very short duration that is invisible to subscribers The devise settings usually allow for the choice of the particular line to be tested (deleted) The devise settings usually allow for the choice of the particular line to be tested, the duration and, if it is to do one or both fields. (Per instructions with device) When the unit is set up and turned on it activates a switch that disconnects the IF path for the line duration, typically 53 uSec or 70 uSec. In effect it turns the channel off. If your modulator has the ability to segregate the VIDEO IF, this would be the best choice. If the composite IF must be used [Both Video and Audio IF together], the effect will be a light "clicking" in the TV audio. This is not usually offensive or even noticeable over a short time. When a spectrum analyzer capable of Gated Measurements is used the video line to be “deleted” is selected. The effect is the carrier will be off during the measurement interval and CTB can be measured without actually disrupting the channel. This test now can be performed during normal working hours. This is desirable because it saves the tech being out late (and off the next day) and saves money for overtime. It also is customer friendly, no matter what time the test is done when you turn off the channel you know someone is watching! How it is done with the 860DSP: Using the Advanced Spectrum Analyzer (Option SA-1) set the analyzer for the channel under test. The easiest way to do this is to select the channel with the single channel meter, press GOTO and select the analyzer. The channel will be centered on the screen. Select the RBW and reduce it to 30 kHz. Select the Hold key and place it in “MAX”. Place Marker A on the video carrier. Simplify this by observing the peak marker (the round marker that appears on the carrier) look in the lower right side of the screen at the "Peak" it will show the level and frequency, record that level and move to the Marker A field and type in the video carrier frequency. Marker A will go to that peak. Change to MIN. First you will see the modulation disappear over a short time. In about 15 seconds or less you will see the carrier disappear if the line deletion unit is active. The time for this to happen depends on the settings in the line deletion device. If it is set for an older type analyzer the setting will be for both fields at 70 uSec duration. With this setting the carrier will be removed relatively quickly. If it is set for newer analyzers, it will most likely be set to one field 53uSec and will take a little longer. When the carrier is gone, observe the CTB as a small hump in the noise. Place the marker on that peak and record the level quickly. CTB is a changing value dependent of the various signal peaks occurring together, you do not want to allow the minimum value to be recorded. Add the two together for CTB Using the Advanced Spectrum Analyzer (Option SA-1) set the analyzer for the channel under test Select the RBW and reduce it to 30 kHz Select MAX Place Marker A on the video carrier and record level Change to MIN When the carrier is gone observe the CTB as a small hump in the noise Place the marker on that peak and record the level Use Marker B to measure CSO and record level Add absolute values of video level to CSO/CTB level Example: Carrier at 10 dBmV, CTB at -50 dBmV add the absolute values = 60 dBc

CSO/CTB MODE Once you have selected the desired channel, the 860 DSP will display the video carrier level To measure CSO/CTB you must briefly turn off the video carrier. When the 860 DSP sense that the carrier has been removed, it will measure and display the CSO and CTB 860 DSP CSO CTB Measurement Composite Triple Beat (CTB) has Traditionally required the channel to be turned off because the disturbance is located below the carrier New devices have been produced to combat this problem. They can turn the channel off at a specified time for a very short duration that is invisible to subscribers The devise settings usually allow for the choice of the particular line to be tested (deleted) The devise settings usually allow for the choice of the particular line to be tested, the duration and, if it is to do one or both fields. (Per instructions with device) When the unit is set up and turned on it activates a switch that disconnects the IF path for the line duration, typically 53 uSec or 70 uSec. In effect it turns the channel off. If your modulator has the ability to segregate the VIDEO IF, this would be the best choice. If the composite IF must be used [Both Video and Audio IF together], the effect will be a light "clicking" in the TV audio. This is not usually offensive or even noticeable over a short time. When a spectrum analyzer capable of Gated Measurements is used the video line to be “deleted” is selected. The effect is the carrier will be off during the measurement interval and CTB can be measured without actually disrupting the channel. This test now can be performed during normal working hours. This is desirable because it saves the tech being out late (and off the next day) and saves money for overtime. It also is customer friendly, no matter what time the test is done when you turn off the channel you know someone is watching! How it is done with the 860DSP: Using the Advanced Spectrum Analyzer (Option SA-1) set the analyzer for the channel under test. The easiest way to do this is to select the channel with the single channel meter, press GOTO and select the analyzer. The channel will be centered on the screen. Select the RBW and reduce it to 30 kHz. Select the Hold key and place it in “MAX”. Place Marker A on the video carrier. Simplify this by observing the peak marker (the round marker that appears on the carrier) look in the lower right side of the screen at the "Peak" it will show the level and frequency, record that level and move to the Marker A field and type in the video carrier frequency. Marker A will go to that peak. Change to MIN. First you will see the modulation disappear over a short time. In about 15 seconds or less you will see the carrier disappear if the line deletion unit is active. The time for this to happen depends on the settings in the line deletion device. If it is set for an older type analyzer the setting will be for both fields at 70 uSec duration. With this setting the carrier will be removed relatively quickly. If it is set for newer analyzers, it will most likely be set to one field 53uSec and will take a little longer. When the carrier is gone, observe the CTB as a small hump in the noise. Place the marker on that peak and record the level quickly. CTB is a changing value dependent of the various signal peaks occurring together, you do not want to allow the minimum value to be recorded. Add the two together for CTB Using the Advanced Spectrum Analyzer (Option SA-1) set the analyzer for the channel under test Select the RBW and reduce it to 30 kHz Select MAX Place Marker A on the video carrier and record level Change to MIN When the carrier is gone observe the CTB as a small hump in the noise Place the marker on that peak and record the level Use Marker B to measure CSO and record level Add absolute values of video level to CSO/CTB level Example: Carrier at 10 dBmV, CTB at -50 dBmV add the absolute values = 60 dBc

CSO/CTB MODE The worst case CSO/CTB readings are displayed below the channel. A detailed list of CSO/CTB components are displayed in a tabular form at the lower left of the screen. The 860 DSP will hold the CSO/CTB reading after you turn the carrier back on. 860 DSP CSO CTB Measurement Composite Triple Beat (CTB) has Traditionally required the channel to be turned off because the disturbance is located below the carrier New devices have been produced to combat this problem. They can turn the channel off at a specified time for a very short duration that is invisible to subscribers The devise settings usually allow for the choice of the particular line to be tested (deleted) The devise settings usually allow for the choice of the particular line to be tested, the duration and, if it is to do one or both fields. (Per instructions with device) When the unit is set up and turned on it activates a switch that disconnects the IF path for the line duration, typically 53 uSec or 70 uSec. In effect it turns the channel off. If your modulator has the ability to segregate the VIDEO IF, this would be the best choice. If the composite IF must be used [Both Video and Audio IF together], the effect will be a light "clicking" in the TV audio. This is not usually offensive or even noticeable over a short time. When a spectrum analyzer capable of Gated Measurements is used the video line to be “deleted” is selected. The effect is the carrier will be off during the measurement interval and CTB can be measured without actually disrupting the channel. This test now can be performed during normal working hours. This is desirable because it saves the tech being out late (and off the next day) and saves money for overtime. It also is customer friendly, no matter what time the test is done when you turn off the channel you know someone is watching! How it is done with the 860DSP: Using the Advanced Spectrum Analyzer (Option SA-1) set the analyzer for the channel under test. The easiest way to do this is to select the channel with the single channel meter, press GOTO and select the analyzer. The channel will be centered on the screen. Select the RBW and reduce it to 30 kHz. Select the Hold key and place it in “MAX”. Place Marker A on the video carrier. Simplify this by observing the peak marker (the round marker that appears on the carrier) look in the lower right side of the screen at the "Peak" it will show the level and frequency, record that level and move to the Marker A field and type in the video carrier frequency. Marker A will go to that peak. Change to MIN. First you will see the modulation disappear over a short time. In about 15 seconds or less you will see the carrier disappear if the line deletion unit is active. The time for this to happen depends on the settings in the line deletion device. If it is set for an older type analyzer the setting will be for both fields at 70 uSec duration. With this setting the carrier will be removed relatively quickly. If it is set for newer analyzers, it will most likely be set to one field 53uSec and will take a little longer. When the carrier is gone, observe the CTB as a small hump in the noise. Place the marker on that peak and record the level quickly. CTB is a changing value dependent of the various signal peaks occurring together, you do not want to allow the minimum value to be recorded. Add the two together for CTB Using the Advanced Spectrum Analyzer (Option SA-1) set the analyzer for the channel under test Select the RBW and reduce it to 30 kHz Select MAX Place Marker A on the video carrier and record level Change to MIN When the carrier is gone observe the CTB as a small hump in the noise Place the marker on that peak and record the level Use Marker B to measure CSO and record level Add absolute values of video level to CSO/CTB level Example: Carrier at 10 dBmV, CTB at -50 dBmV add the absolute values = 60 dBc Note: CSO is maximum at the lowest and highest frequency, CTB tends to be maximum at the mid-frequencies

Distortion Summary Known frequencies
Measure relative to visual carrier amplitude Modulation and/or carrier off

Questions?

Problems Simulation (C/I,CSO & CTB)

Hum Measurements

Low Frequency Disturbances – Hum FCC 76.605 (a) (10)
Specification: < 3% Picture effect: Horizontal bars or stripes slowly moving up the picture. Spectrum Analyzer Spec: ± 0.5% for levels < 5% Number of Test Points: 6+ Number of Channels 4+ Frequency of Test Two times per year Location of Test: Subscriber terminal and head end Center Frequency Span Resolution BW Video BW Sweep Time Reference Level Scale Center on visual carrier Zero Hz 1 MHz 1 MHz (mod ON), 1 kHz (mod OFF) Auto Distortion above bottom div 10 dB/div Spectrum Analyzer Settings` Measurement Notes: NCTA is peak-to-peak to peak level ratio, IEEE is peak to average level ratio. FFT used to see harmonic content.

The definition and origins of hum distortion How it looks to your subscriber FCC regulations Measurement on signal level meter and spectrum analyzer Diagnostics to help find the source

Why the Subscriber Complains About Hum
Hum causes horizontal bars rolling from bottom to top

Hum Is Important Because...
May indicate more serious maintenance problem, or it may not Either way it upsets subscriber

Definition and Regulations
Demodulated Carrier Voltage Time Peak Peak-to-Peak % Hum = 100 X Hum is amplitude modulation of the visual carrier The level is a % of the total voltage FCC says 3% is limit

How Hum is Generated Power line frequencies: 60 and 120 Hz
Power supply Mains supply Ground loops DC Power Supply AC In Low Line Voltage (120 Hz) Wrong Voltage Setting (120 Hz) Distribution Amplifier Connector Corrosion (60 Hz) Bad Filter Capacitor (120 Hz) Bad Power Supply Diode (60 Hz) Trunk Feed

Hum Measurement Techniques
Spectrum analyzer demodulates carrier and measures the voltage swings Signal level meter filters and measures the power line components carrier input IF mixer local oscillator bandpass filter detector video sweep generator time How does dsp do it?

Signal Level Meter / Analyzer Comparison
Hum measured in the Time Domain Cable analyzer more accurate, has wider range SLM, portability for quick looks Need a screen dump

Hum Mode In HUM MODE the 860DSP displays the amplitude of the 50/60Hz and 100/120Hz and low frequency interference HUM MODE requires a minimum signal level of dBmV The GO TO SOFTKEY gives a rapid access to the SPECTRUM and SCAN modes Rule of thumb: 60 Hz is passive (Capacitor) 120 Hz is active (Power Supply in Amp) typical problem is the house amp Use the <1K reading for maintenance and recording for FCC records. Do not use the 60 or 120 Hz readings for the FCC records. The FCC requires that HUM is all low frequ<1K

Hum Measurement Summary
Hum is annoying, but also may point to bigger problems Hum may be measured easily and accurately by SLM or cable analyzer

Questions?

Problems Simulation (Hum)

Digital Measurements What you need to know

What you will learn Channel Power Constellation MER BER Equalization
Statistics Settings

Channel Power Channel power is measured in the frequency domain over the specified bandwidth. The logarithmic values (dB) are converted to linear values, averaged and the converted back to a log value. If video averaging is used with normal marker and normalizing from Resolution BW to channel BW then a 2.5dB too low of a reading will be obtained. It is important to set Digital Channel Power levels relative to the analog channels to optimize signal to noise while avoiding laser clipping.

Constellation Typical Problems Coherent Interference
Incoherent Interference System Noise Phase Noise Gain Compression IQ Imbalance CONSTELLATION Mode Shows a picture of the quality of the digital signal. Identifying a specific constellation pattern on the grid and associating this pattern with a specific type of impairment quickly leads to troubleshooting options that minimize or eliminate the impairment. (A good QAM signal would show the dots in the center of each square on the grid.)

Measurement Examples Coherent Interference
If the coherent interference is great enough, the plot of all dots landing in a given box will form a rough ring, usually distorted by incidental noise Sources of coherent interference may include: Intermodulation products PC clock harmonics Broadcast transmitters These displace the symbols in a given box into a tell-tale circular pattern Coherent as applied to light waves, having identical frequency and identical phase, and traveling in the same direction. Lasers produce coherent light.

Measurement Examples Incoherent Interference
QAM signal always suffers some noise contamination Motors Relays and Power Equipment Transmission devices in the distribution path Noise jitters the displayed symbol around its nominal point in the constellation "box", so the sum of all symbols that occupy a given box in some length of time form a "cloud", with each symbol displaced to a slightly different spot due to noise If there is enough noise contamination, the constellation diagram will show some of the symbols displaced past Decision Thresholds, becoming "bit errors" Incoherent as applied to light waves, having a jumbled mixture of frequency phase, and possibly direction. In real systems, the QAM signal always suffers some noise contamination caused by motors, relays and power equipment and by transmission devices in the distribution path Noise jitters the displayed symbol around its nominal point in the constellation "box", so the sum of all symbols that occupy a given box in some length of time form a "cloud", with each symbol displaced to a slightly different spot due to noise If there is enough noise contamination, the constellation diagram will show some of the symbols displaced past Decision Thresholds, becoming "bit errors"

System Noise Constellation displaying significant noise
Dots are defused Incoherent (Noise) interference In real systems, the QAM signal always suffers some noise contamination caused by motors, relays and power equipment and by transmission devices in the distribution path. Noise jitters the displayed symbol around its nominal point in the constellation “box,” so the sum of all symbols that occupy a given box in some length of time form a “cloud,” with each symbol displaced to a slightly different spot due to noise. If there is enough noise contamination, the constellation diagram will show some of the symbols displaced past Decision Thresholds, become “bit errors.” The constellation displays the dots defused or spread out. System Noise can be caused by a bad fiber link, or over-padding the input gain stage of an amplifier. It can also be caused by intermodulation distortion, which is caused by digital signal loading.

Measurement Examples Phase Noise
However, a defective modulator or processor can add appreciable phase noise to the signal, resulting in a constellation that appears "rotated" around the center of the graph "Phase noise" is a term for the phase-related instabilities of an oscillator If the oscillator is involved in processing a signal (as a local oscillator, for example) these instabilities are impressed on the signal The oscillators in signal processing devices are designed to add very little phase noise to the signals they handle

Measurement Examples Gain Compression
In the resulting constellation, the corners are pulled in giving the graph a "bowed", rather than square, shape Gain compression is a signal distortion caused by overdriving an active component (amplifier or processor) in the signal path, or by defective active components

IQ Imbalance The constellation is taller than it is wide
Difference in gain I channel Q channel I Q Imbalance baseband amplifiers filters digital modulator. Q I I Q Imbalance The constellation is taller than it is wide. This is a difference between the gain of the I and Q channels. I Q Imbalance is caused by baseband amplifiers, filters, or the digital modulator.

average symbol magnitude
MER Calculation I Q average symbol magnitude magnitude average error ( ) average error magnitude MER (dB) = 20 x log The Modulation Error Ratio (MER) is the average error over a relatively large number of symbols. This is a good metric for small errors.

Worsening Signal Quality
Threshold and Margin Digital Perfect Picture Quality Analog No Picture With Analog Video Systems, the picture degradation was directly related to Carrier to Noise. As C/N decreased, the picture quality gradually degraded as well. With Digital Video Systems, the picture quality is near perfect until the receiver can no longer correct errors and finally looses lock and freezes. This happens with a very small decrease in carrier level when it is near that boundary (the cliff edge). The Estimated Noise Margin (ENM) value on the QAM screen gives an indication of how close one is to the cliff edge. Worsening Signal Quality

BER - Bit Error Rate Before Forward Error Correction
Calculated from FEC errors After Forward Error Correction FEC encoding uses extra bits so is overhead on the data stream. The level of FEC is set by the standard used. In a cable modem return (upstream) the level of FEC can be set in the modem’s modulation profile.

Equalization Equalization can be turned on or off
Some like to measure MER with EQ on and off 8 Feedforward and 24 Decision Feedback Equalizer Coefficients Display of distance to reflection In Channel Frequency Response Displays peak to peak flatness result Group Delay Displays peak to peak group delay result It is good to know how hard the equalizer is working. Since it will fail to decode if it is taken past it’s limits. Equalizer implementation is important as well. This limits how much (magnitude and time offset) it can compensate. As well as the resolution of the graphs.

Return Loss Cable modem specified 6dB return loss
Incident wave is returned this much lower Unterminated ports cause reflections Reflections setup standing waves Loss is your friend Problem for low value tap plates Shows up in Equalizer display The cable modem return loss specification is poor. This guarantees reflections. An unterminated port reflects all power back to the source. But loss is your friend. High tap plate values attenuate the reflections and keep them from the rest of the system.

Statistics Averaging MER masks transient problems
System sweep Ingress/Leakage Distortions Long time record confirms problem The statistics screen allows long testing intervals so that intermittent disturbances can be seen. Usually good MER but intermittently bad MER spikes can be seen. Pre FEC BER and possibly bad Post FEC BER spikes can also be seen.

Settings Select Standard Select QAM format
J83 A, B or C (The US uses B) Select QAM format Non standard symbol rate values Proprietary system No FEC Optimize measurement Once the standard is set (J83-B) then pick 64 or 256 QAM and should be good. Non standard symbol rates can be handled by setting symbol rate to manual and keying it in. Pick the closest standard first (J83 A, B or C). If testing a source with NO FEC encoding as in the case of a QAM modulated signal generator then that option is available under the Standard menu. Polarity, reverse allows testing at IF. Automatically setting the attenuator and preamp is best for the digital demodulator but just in case there is a situation where control is needed, it is available.

Digital Power Designed for digital carriers
USA - 6 MHz filter Europe - 8 MHz filter The wider the bandwidth for a given peak power The higher the average power Bandwidth must be taken into account for the accurate measurement of digital signals The average power (with digital carriers) is not affected by the programming content The amount of distortion in a system is related to the total power of all of the carriers Digital carriers are different in signal content, distribution of power, and are measured differently. The amount of distortion in a system is related to the total power of all of the carriers which makes accurate power measurements critical for optimum performance. The wider the bandwidth for a given peak power. The higher the average power. Bandwidth must be taken into account for the accurate measurement of digital signals. Absolute Vs Relative Power - Power is measured either as an absolute level or relative to another power level. Carrier levels are absolute measurements and are measured in power units, one example dBmV. Relative power measurement examples are C/N, Delta Audio to Video, CSO & CTB which are measured in dB. The shape of the carrier also affects the average power. Older or previous Signal Level Meters and Spectrum Analyzers make multiple measurements across the frequency range of a digital carrier. The power of each of these measurements is summed and the average power of the whole channel is calculated. Other SLMs and Spectrum Analyzers correct for the shape factor of their 300 KHz IF filters to ensure a correct reading. Digital measurements must measure all of the power at all frequencies within the channel, and reject any adjacent channel power. The average power (with digital carriers) is not affected by the programming content.

Digital Carrier Levels
64 QAM signals 10 dB below video (Typical) 256 QAM signals 6 dB below video (Typical) Digital signals work well until very close to the point of failure. This makes measurement of digital carriers critical to determine the system margin. Signal level, MER, and BER are the vital measurements. The BER Mode helps to find any BER problems

Adaptive Equalizer Response
Digital Carriers sensitive to reflections Tree rubs Squirrel chews Loose Connectors Distance to Fault Equalizer Mode The Adaptive Equalizer corrects the effects of reflections in the transmission path. The Equalizer Mode indicates the strength of specific reflections, their location in relation to the test point location, and how hard the equalizer is working to correct them. A primary function of this mode is to help the user maintain low levels of equalizer stress by locating excessive equalization at specific QAM demodulator digital filter coefficients that require correction. Digital Carriers can be very susceptible to reflections in the cable caused by a variety of problems such as bad splitters, bad connectors, kinks, squirrel chews, Godzilla backhoe, and tree rubs. Reflections can cause errors in the signal because a reflection of a particular bit of data can overlap data bits that come later. Set top converters have an adaptive equalizer that senses the amount of reflections and compensates for them. It’s important to know how hard the adaptive equalizer is working to determine if there is any margin for system degradation. The adaptive equalizer changes the level at a particular time. This time matches the time which the reflection occurs. The gain is reduced only at this time, thus reducing the reflection.

QAM Measurements Constellation Display MER BER True BER or Estimated
Digital HFC services are distributed using a modulation system that transmits two data streams, each carrying its own independent information. Conventionally, these streams are called “I” and “Q.” Quadrature Amplitude Modulation *QAM) is a means of modulating both streams onto one RF carrier. The transmitted values of I and Q occupy only a few pre-defined, widely separated states. A modulation “protocol” (set of rules) prescribes the number of allowed states for each type of modulation. For example, in 16 QAM, the I and Q signals can have only 4 allowable states each; in 64 QAM, each can have eight. Constellation and “Boxes” I and Q streams can be represented as being “in quadrature,” forming a grid that offers I time Q possible states. The grid is conventionally referred to as a “constellation” and may be thought of as an array of “boxes,” with each box representing a particular I – Q “symbol state.” The ideal or “nominal” location for a given symbol stat is the center of the box. The boundary between neighboring boxes is called a “Decision Threshold.”

64 & 256 QAM Constellations Symbol Rate
The Symbol Rate corresponds to the size and shape (bandwidth) of the digital signal. This rate is expressed in “millions of symbols per second” (Msym/s). The default for 64 QAM is The default for 256 QAM is

Constellation Deviation from the ideal location 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 level High noise floor Good MER Poor MER

BER Digital signals work well until very close to the point of failure
Measurement of digital carriers critical to determine the system margin Signal level MER BER The BER Mode helps to find problems

Forward Error Correction
FEC Corrects errors to a point Pre FEC BER (Before Correction) Forward Error Correction (FEC) Forward Error Correction adds redundant information to the data stream to decrease the number of bit errors introduced by the transmission channel. The BER before FEC is the sum of all bit errors correctable and uncorrectable. BER after FEC indicates the number of uncorrectable errors the FEC was unable to correct. The difference between PRE and POST FEC indicate how hard the FEC function is working and how close the system is to failure. The FEC can correct errors up to a point, after which errors are passed on to the decoding circuitry. It’s important to know the Pre and Post FEC BER to know how hard the FEC is working to correct errors. The harder it’s working, the closer the system is to failure. FEC is a method where additional data bits are added to the digital video bit stream to help identify and correct any errors that may be caused by the transmission system. Data errors if not corrected, can cause significant picture impairments that will be seen by the subscriber. The FEC attempts to correct these errors as much as possible. Interleaving is another method of reducing the effect of errors. Interleaving takes the data stream and mixes the transmitted bits in a different order, the error burst is spread out over a larger amount of data, making it easier for the FEC to handle. Errors that exist prior to the FEC circuitry in the set top may be completely removed making it important to determine how hard the FEC is working by checking the Pre-FEC errors and comparing them to the Post-FEC errors. Post FEC BER (After Correction)

Forward Error Correction (FEC)
Pre BER (before FEC) is the sum of all bit errors Post BER (after FEC) indicates the number of uncorrectable errors Adds information to the data stream (parity bit) Parity Bit Odd Even data size vs error correction Pre and Post-FEC Measurements QAM communications systems include the means to patch up some of the bits that become corrupted in transit. “Forward Error Correction” FEC) data, included with the QAM data transmissions, is the information the QAM receiver uses to “fix” the misinterpreted bits. Because Pre- and Post-FEC data quality may differ greatly, BER measurements are typically specified as being either “Pre-FEC” or “Post-FEC,” to indicate whether the data has already been repaired by FEC. Forward Error Correction (FEC) Adds information to the data stream to decrease the number of bit errors introduced by the transmission channel. The BER before FEC is the sum of all bit errors. BER after FEC indicates the number of uncorrectable errors. Which are the errors that FEC was unable to correct and were passed on to the decoding circuitry. The difference between PRE and POST FEC indicate how hard the FEC function is working and how close the system is to failure. By adding an additional bit to a group of bits, errors can be detected within the group. This is known as a parity bit. Even parity means that when the parity bit is added the group of bits including the parity always has an even number of ones. Odd parity means the group would have an odd number of ones. If after transmission the number of ones is no longer even (for even parity), then there must be an error.

How Do I see the Noise when the QAM carrier is present?
Use the QAM EVS (Error Vector Spectrum) The QAM carrier is removed from the spectrum

MER TARGET - THE “CLIFF” EFFECT
What is The “Cliff Effect”?

Crash Operating margin Zone Risk Zone Crash Zone
Up/Downstream QAM >21dB 21dB - 19dB <17dB Downstream QAM >27dB 27dB - 25dB <23dB Downstream QAM >32dB 32dB - 30dB <28dB

Summary Digital level setting MER has it’s limitations Equalizer
Peak to Average MER has it’s limitations Margin and BER Equalizer Can only help so much Statistics show transients Flexible Digital demodulation Digital signals need to be carefully set to insure margin and avoid laser clipping. MER works well for smaller errors but limit out as the signal degrades. The Equalizer compensates for reflections, flatness and group delay. Up to a point. Measurement Statistics show intermittent spikes in MER. Having a digital demod that is not constrained to a single format means it can accommodate worldwide standards and proprietary systems.

Questions?

Problems Simulation (MER & BER)

Signal Leakage Welcome to seminar I am ..............
This seminar has been developed to provide a fundamental understanding of: the following topics: Signal leakage Leakage characteristics Searching for leakage FCC compliance CLI - Cumulative Leakage Index Signal Ingress

Leakage Leakage terminology What is leakage
Why do we monitor for leakage What causes leakage Leakage characteristics Locating source of leakage Ingress The specific chapters of this seminar are Leakage terminology - I will go over various terms commonly used with regard to signal leakage What is leakage - I will define leakage and try to create a mental picture of signal leakage Why do we monitor for leakage - I will discuss the 4 basic reasons for monitoring leakage What causes leakage - I will mention some of the common and unusual causes of leakage Leakage characteristics - I will explain why leakage acts the way it does

Leakage Terminology Egress Radiation (Never Say!!!) Leakage Ingress
uV/M Squelch Calibration Tagging (CT-2 or CT-3) Egress - Older term used among RF engineers - Term still used in other industries Radiation - Original CATV term - Not advisable term around customers Leakage - Fairly recent term which best describes the nature of the problem Ingress - Opposite of leakage - Signal leaking “into” the cable system uV/M - Microvolts per meter -.Preferred unit of measure by the FCC - Leakage measurements are in the same units of measure as radio transmission Squelch - Adjustment to leakage detector determining the leakage amplitude necessary to set off audible alarm of a leakage detector Calibration - Adjustment to leakage detector to assure accurate level reading of leakage

What is Signal Leakage? Definition:
Undesired emission of signals out of an HFC network What is signal leakage? The undesired emission of signal out of an HFC network. We monitor a specific frequency for signal leakage However: 1.) If you leak one you are leaking all frequencies 2.) 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 users Disruptive - to off-air broadcasters Destructive - to the physical condition of the plant if left unrepaired

Ingress & Egress Ingress Egress
RF or electrical energy that enters the coaxial environment Egress RF signal leaking out of the coaxial environment

Why do we monitor for leakage?
4 Primary reasons

Reason #1 to Monitor for Leakage
Prevent Off-Air Broadcast Interference

Spectrum Chart 108MHz 137MHz Off-air Cable Aircraft Radio & Navigation
Broadband 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. TV Aircraft Land mobile Government communications

Reason #2 to monitor for leakage
Meet FCC Compliance

Cumulative Leakage Index (CLI)
CLI is the net effect of the combination of all the leaks in the system added together These cumulative leaks form an invisible cloud of unwanted RF energy over the cable system Compliance = 64 or less

CLI Quarterly Rules Ride out 100% of system and log all leaks
Log should include Date found and Date fixed Documenting leakage levels isn’t required for this drive out Actual practice for your system may vary!

CLI Annual Rules Ride out 75% of the oldest part of the system and log all leaks location and measured level Must be performed within a reasonable period of time Usually within 2 wks of due date

Required Actions All leaks 20uV/m must be logged and fixed
Only leaks above 50 uV/m are used in CLI calculation All measurements taken outside MHz must be converted as if they were taken within the band

uV/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 1uV of energy

Eliminates Ingress Improves System Performance Reduces Repeat Service Calls Reduces Drop Calls for VoIP

Locate Physical problems within the plant

Common Causes 70% of all leakage is caused by problems between the tap and entry to the house Aging and environmental stress Physical trauma to cables or connectors Loose drop connectors Inferior quality coaxial cable, passives, or connectors Loose hard line connectors Common causes: - cracks in cable - corroded or loose connectors - loose device enclosures

Other Causes of Leakage
Improperly installed connectors Cracks in the trunk and feeder cable Animal chews Poorly-shielded drop cable Bad connectors at the tap Bad/loose port terminator Corroded connectors Unusual causes: - squirrel chewing on hardline coax - dog chewing RG coax - puncture in coax at midspan locations clamps without the use of spacers tree branch rubbing or falling on cable projectiles - gunshots, arrows, pellets, etc. vandalism - customer caused leakage use of antenna on A/B switch illegal outlets using inferior materials tampering with settop box

Other Causes Continued
Customer installed equipment Damaged amplifier housing or loose amplifier housing lids Broken tap ports Poor installation of splices and connectors Poorly-shielded customer premise equipment

Acceptable Procedures for Leakage Measurement
Use a calibrated halfwave dipole antenna Antenna 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 CLI Fly-over

Polarization Angle Dipole Monopole
Leakage 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.

Leakage Antennas-Whip

Leakage Antennas-Dipole

Seeker Lite Frequency Agile Leakage Detector
Built-in directional Antenna

Seeker GPS Data Storage GPS Equipped WiFi Upload Capable MapQuest Mapping Server Based

Signal phasing Radiated signals can: 1.) Reflect off surfaces
` 2.) Travel on conductive surfaces 3.) Occur from more than one nearby location These “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.

Standing Waves As 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.

Electrical Noise Electrical 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.

Leakage Field Strength
Amp Consider 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. Lowest Potential Highest Potential

Distance Correction Reading x Distance
= Corrected Reading 10 Why 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.

Patrolling for Leakage
10 feet 20uVm 100 feet Pinpointing 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 uVm

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. 20-30 feet

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.

Ingress on Analog Channels
Lines in picture Ghosting Pay-per-view problems Interference with two-way radio services using the same frequencies Repeat Service Calls Interference 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

Ingress on Digital Channels
Macro Blocking (Tiling) Freeze Frame Picture and Sound go to black Robotic Voice Data Packet Loss or slower speeds Dropped VoIP Calls Repeat Service Calls Interference 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 data Freeze frame - This happens when ingress has created significant Bit Error causing the loss of an entire refresh frame Loss of picture and sound to black - This happens when ingress is severe enough to completely destroy a data stream into unusable garbage.

Why and How to Check for Leakage ?

Public Safety Quality of Service
Potential interference with aircraft communication/navigation The cable system could interfere with off-air signals Quality of Service Ingress impairs picture quality Ingress/Egress (leakage) usually is a sign of a pending equipment failure 3 97 97

Increased implementation of services requiring return path activation
If a system has egress it will most likely have ingress Ingress brings the viability of two-way services into question VoIP demands higher network reliability 4 98 98

Common Leakage Sources
Splices and fittings- Water and weather can result in pulled out, loose or corroding fittings Splices at taps, line extenders, splitters, amps and ground blocks Illegal hookups involving twin leads, cheap passive devices, house amplifiers, poor or no connectors, and improperly terminated splitters 15% jumpers from drops to taps or ground blocks 75% of leaks come from subscribers home 100 100

Recommended frequency range is 108-137MHz
Measurements must be repeatable Dipole 3 meters from leak above the ground Dipole should be rotated about a vertical axis and maximum reading recorded Other conductors must be 3 or more meter away from the measuring antenna The measurement range should be free from obstacles Greater than 20 uV/m at a distance of 3 meters 7 103 103

Questions?

Problems Simulation (Leakage)

=====================
Thank you - Gracias Trilithic Applications Engineering Tel: ===================== Incospec Communications Inc. Value Adder Trilithic Re-Seller for Caribbean Mario Sebastiani Bernard How

Short Company Profile August 2008

Who we are… Incospec is a performance-oriented, VAR & expert partner for its customers in the broadband telecommunications industry. More specifically, our expertise is in the following fields : - Headends and HFC networks for CATV - MMDS and Wireless Broadband - TVRO/Satcom - TV/FM Radio Broadcast - Data Transmission For over 25 years, from our headquarters in Montréal, Canada, we have been serving customers in North America and around the world. 154154

What we offer… We offer system and equipment solutions for the broadband telecommunications markets. We also offer equipment modifications & upgrades, refurbished equipment and in or out of warranty repairs in our fields of expertise. Our alliances with reputable manufacturers of high quality equipment make a winning combination. Trilithic’s broadband instruments is a good example 155155

TRILITHIC’s value added reseller for Caribbean…
TRILITHIC Test Equipment Core Market Signal analysis Reverse/Forward maintenance & monitoring Leakage detection system 156156

Trilithic’s equipment…
Installation TR-2 Model Two Seeker Lite TR 2040 RSVP2 Service & Maintenance 860 DSPi 8821Q Seeker GPS Supporting Products CT-2 Channel Tag FST 8300 9581 SSTR4 9581 RSA Speed Sweep Monitoring 860 DSPh Guardian II 157157

Trilithic’s Expertise…
Forward Monitoring & Remote Signal Analysis Return Path Monitoring & Remote Spectrum Analysis System Sweep (forward & reverse) Return Path Loss Testing, Alignment & Certification Throughput & VoIP RTP Testing Upstream QAM Testing Subscriber Premises Installation Service Assurance Test Data Management for Team Efficiency Automated CLI Leakage system assisted by GPS Drop integrity validation 158158

What represents us… 159159

http://www.incospec.com http://www.trilithic.com Contact…
For your future cost effective test equipment requirements for the Headend and all parts of the HFC network, we invite you to visit Mario Sebastiani Business Development

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