Plant Reliability Larry Jump JDSU Field Applications Engineer

Plant Reliability Larry Jump JDSU Field Applications Engineer
TAC Opt. 3 / 2

Agenda 3 major areas of concern
Coax Fiber Inside plant

To provide better service to our customers in light of competition
Purpose To provide better service to our customers in light of competition Maintain plant instead of reacting to problems Be alerted to issues before the customer notices Maintain reliability for essential services To increase revenues

The outside plant

WHY SWEEP? Less manpower needed
Sweeping can does reduce the number of service calls VOD not working Internet not working Channel 12 video problems Cracked hardline found with SWEEP

WHY SWEEP? Loose Face Plate No Termination

Sweep vs. Signal Level Meter Measurements
References: Sweep systems allow a reference to be stored eliminating the effect of headend level error or headend level drift. Sweep Segments: Referenced sweep makes it possible to divide the HFC plant into network sections and test its performance against individual specifications. Non-Invasive: Sweep systems can measure in unused frequencies. This is most important during construction and system overbuilding. BEST Solution to align: Sweep systems are more accurate, faster and easier to interpret than measuring individual carriers. 56

Frequency Response Definition
System’s ability properly to transmit signals from headend to subscriber and back throughout the designed frequency range Expected Results (Traditionally): n/10 + x = max flatness variation where n = number of amplifiers in cascade where x = best case flatness figure (supplied by manufacturer) Expected Results in current HFC Networks: Typically < 3 to 4 dB max flatness variation anywhere in the network (check with your Manager for max flatness variation limits) 55

Forward Path Considerations
Diverging System Constant Outputs Channel Plan to Match Fixed Signals video / audio / digital carriers Sweep Telemetry Carriers, 1MHz wide System Noise is the sum of cascaded amplifiers Balance or Align (Sweep) compensate for losses before the amp 6 6

Sweep Reference Considerations
Typically the node is used for the reference Use test probe designed for node/amp It’s a good engineering practice to store a new reference each day Establish reference points to simplify ongoing maintenance (sweep file overlay) Need to know amps hidden losses in return path (Block diagrams / Schematics) Need to know where to inject sweep pulses and the recommended injection levels Once the transmitter is configured properly, the next step is to store a reference in the receiver to enable accurate normalized tests at each amplifier output test point. This reference is usually stored at the node. The response at subsequent amplifiers is compared with this reference to verify operation according to the unity gain principle (theoretically every amplifier will have the same output levels and response). 16

Unity Gain in the forward path
L R R Each amplifier compensates for the loss in the cable and passives before the amplifier under test. The system is aligned so that the levels at each green arrow are exactly the same. In the forward path, signals originate at the headend and are transmitted to many customer drops. One output feeds many inputs. In the forward system the outputs of like devices are typically set to same output level. Each amplifier compensates for the cable and passive loss before it. This principal (Gain = Loss) is Unity Gain. Level changes in the forward path occur due to changes in cable loss caused by temperature. Automatic level or gain controls (ALC or AGC) are located in the amplifiers to compensate for these changes in level. A section of the alignment procedure for the forward path involves setting the operating point for the automatic control circuit. In short all amplifiers have a constant output to compensate for the losses in the cable and any passives before the amplifier.

Why do we need Unity Gain?
32/26 31/25 30/24 29/23 22 22 22 22 23 23 23 If unity gain is not observed then the signal impairments quickly overtake the desired signals. In the case shown above, we experience a 3 dB degradation in CNR with just 3 amps in cascade. In today’s systems, 3 dB would easily make or break us. If the signals were 1 db high at each amp, then CSO would be worse by 6 dB and CTB would be worse by 3 dB. It is very important to maintain constant levels! If Unity Gain is not observed distortions and or noise build up quickly!

Forward Sweep Display Reference Name dB/div Max/Min Markers

A Sweep Finds Problems That Signal Level Measurements Miss
Misalignment Standing Waves Roll off at band edges 6 6 6

Sweeping Reverse Path Goals
The objective in reverse path alignment is to maintain unity gain with constant inputs and minimize noise and ingress. Set all optical receivers in the headend to same output level and ideally the same noise floor to optimize C/N ratio. The reverse path noise is the summation of all noise from all the amplifiers in the reverse path. Adjust sweep response to match 0dB flat line Sweep reference and 0dBmV Telemetry level 11 12 12

Before reverse sweeping begins….
Optimize the upstream node Splitting, combining and padding considerations in the headend.

Return Optics We discuss this first because it has the greater impact on the MER at the CMTS input because it has the lowest dynamic range Optimized by measuring NPR at the input to the CMTS by injecting different total power at the input to laser. Carriers should be derated according to bandwidth using power per hertz. Not part of the unity gain portion of the HFC plant. Set up is laser and node specific The input to the laser and the OMI setting are normally taken care of at the factory

NPR Measurement Measured by injecting a wideband noise source with a notch filter at the input. Then measuring essentially the noise to the notch at the output. Measured as 10 log Power/hz of the signal/Power/hz of the notch noise The lower the signal the lower the CNR, the higher the signal, the more distortion. Input starts low and then raised in 1 dB steps

Power per Hertz Calculation
dBmV/Hz = Total Power – 10 Log (BW) dBmV/HZ = 45 – 10 Log (37,000,000) dBmV/ Hz = 45 – 10 (7.57) dBmV/ Hz = 45 – 75.7 dBmV/ Hz = -29.3 Total Power Input for 6.4 MHz 64 QAM dBmV = Log (BW) dBmV = Log (6,400,000) dBmV = (6.8) dBmV = dBmV = 38.7

REVERSE LEVEL 20 dBmV Optical Receiver NODE 20 dBmV Optical Receiver NODE Combiner Reverse Optical Receiver NODE Optical Receiver NODE Pad for 0 dBmV All signal levels must be set to same output level at the optical receiver in the headend or hubsite with the same input at the node. FREQ CHAN ENTER FCN CLEAR help status alpha light abc def ghi jkl mno pqr stu vwx yz space +/- 1 2 3 4 5 6 7 8 9 x . FILE AUTO SETUP TILT SCAN LEVEL C/N HUM MOD SWEEP SPECT PRINT System Sweep Transmitter 3SR Stealth Sweep 13 14 14

REVERSE LEVEL 20 dBmV Optical Receiver NODE 20 dBmV Optical Receiver NODE 20 dBmV Combiner Reverse Optical Receiver NODE Optical Receiver NODE Pad for 0 dBmV All signal levels must be set to same output level at the optical receiver in the headend or hubsite with the same input at the node. FREQ CHAN ENTER FCN CLEAR help status alpha light abc def ghi jkl mno pqr stu vwx yz space +/- 1 2 3 4 5 6 7 8 9 x . FILE AUTO SETUP TILT SCAN LEVEL C/N HUM MOD SWEEP SPECT PRINT System Sweep Transmitter 3SR Stealth Sweep 13 14 14

REVERSE LEVEL 20 dBmV Optical Receiver NODE 20 dBmV Optical Receiver NODE 20 dBmV Combiner Reverse Optical Receiver NODE 20 dBmV Optical Receiver NODE Pad for 0 dBmV All signal levels must be set to same output level at the optical receiver in the headend or hubsite with the same input at the node. FREQ CHAN ENTER FCN CLEAR help status alpha light abc def ghi jkl mno pqr stu vwx yz space +/- 1 2 3 4 5 6 7 8 9 x . FILE AUTO SETUP TILT SCAN LEVEL C/N HUM MOD SWEEP SPECT PRINT System Sweep Transmitter 3SR Stealth Sweep 13 14 14

REVERSE LEVEL 20 dBmV Optical Receiver NODE 20 dBmV Optical Receiver NODE 20 dBmV Combiner Reverse Optical Receiver NODE 20 dBmV Optical Receiver NODE 20 dBmV Pad for 0 dBmV All signal levels must be set to same output level at the optical receiver in the headend or hubsite with the same input at the node. FREQ CHAN ENTER FCN CLEAR help status alpha light abc def ghi jkl mno pqr stu vwx yz space +/- 1 2 3 4 5 6 7 8 9 x . FILE AUTO SETUP TILT SCAN LEVEL C/N HUM MOD SWEEP SPECT PRINT System Sweep Transmitter 3SR Stealth Sweep 13 14 14

REVERSE NOISE Noise -35 dBmV Optical Receiver NODE Noise -35 dBmV Optical Receiver NODE Combiner Reverse Noise -35 dBmV Optical Receiver NODE Noise -35 dBmV Optical Receiver NODE If your headend has multiple reverse trunks you will need to patch in the appropriate trunk to be swept. It’s a good idea to set up a patch panel to quickly move the reverse sweep to different trunks. Ideally all combined nodes should have same noise floor to maximize C/N ratio. FREQ CHAN ENTER FCN CLEAR help status alpha light abc def ghi jkl mno pqr stu vwx yz space +/- 1 2 3 4 5 6 7 8 9 x . FILE AUTO SETUP TILT SCAN LEVEL C/N HUM MOD SWEEP SPECT PRINT System Sweep Transmitter 3SR Stealth Sweep 12 13 13

Headend combining and splitting
Other Return Services CMTS PathTrak The headend lash up should be carefully planned. Notice that even though there are only 4 return services that 8 way splitters are used with open ports terminated. This allows for future expansion and a test point without having re-engineer the entire return path. Notice the pad on the input to the CMTS port. This should be padded so that the input is the optimum 0 dBmv with the reference signal injected at the node. Again that forces the modems in the field to run at their highest levels to maximize C/I. Set top converter FREQ CHAN ENTER FCN CLEAR help status alpha light abc def ghi jkl mno pqr stu vwx yz space +/- 1 2 3 4 5 6 7 8 9 x . FILE AUTO SETUP TILT SCAN LEVEL C/N HUM MOD SWEEP SPECT PRINT System Sweep Transmitter 3SR Stealth Sweep

Return Sweep considerations
Instead of point to multipoint, the system is multipoint to point Unity gain at the inputs to the amplifiers Telemetry carriers upstream and downstream Noise and ingress are additive from the entire node. One bad drop can take down the entire node. Channel Plan to match bursty digital signals. No sweep points on upstream carriers Return Sweep compensates for losses after the amp Set telemetry carrier level and sweep level to the same thing.

Advantages of return sweep over the older methods
Not as labor intensive as the older methods. Align forward and reverse with the same stop at the amplifier No cumbersome equipment in the field or the headend Minimum use of bandwidth for test equipment Control over the measurements We are aligning the entire spectrum in both directions, not just 2 carriers! Using a return sweep system is the most efficient method for alignment and troubleshooting of the return path.

5 things you need to know to set up your return path correctly
Know your equipment Block diagrams of amplifiers, nodes, receivers, etc. Test Equipment Determine reverse sweep input levels Determine reference points Optimize return lasers portion first Sweep coaxial portion of the plant Here are 5 steps you should consider before attempting to align your return path. Let’s discuss each one individually.

Typical Node RF Block Diagram
STATION FWD EQ PAD LOW PASS FILTER H L REV Switch Diplex Filter PORT 4 Port 4 Output TP REV Switch Diplex Filter PORT 6 Port 6 Output TP H L PORT 3 Port 3 Fwd Signal from Optical Rcvr. H L REV Switch Diplex Filter PORT 5 Port 5 Output TP Return Signal to Optical Transmitter Notice the test points of this node. The test points on the outside of the diplexer are directional for the forward direction. If the return path is viewed from these ports, it will be at a greatly reduced amplitude. The test points inside the diplexer are also directional, but for the return path. The bottom 2 legs are combined in the return through a splitter, but since the test points are directional too, ingress from one leg would be greatly reduced if not eliminated if viewed on the the other return test point. How are your amplifiers and nodes configured?

Typical RF Bridging Amplifier Block Diagram
(1) Test Points are Bi-Directional Notes: ALL test points can be -20 or -25dB ALC PIN DIODE ATTEN Interstage EQ Pre- Amplifier Plug-In PAD High Pass Filter Diplex H L IGC Main Reverse Low Pass ALC Circuit Bridger AC Power RF/AC RF Aux REV  TRANSPONDER RF INTERFECE BRIDGER RF TEST REVERSE STATION PORT 1 PORT 5 PORT 2 PORT 3 PORT 6 BRIDGE (1) Notice her that the test points are bi-directional, that means that both the forward and return signals are present and that means a LPF is necessary. In this instance also notice that the only isolation between the test points is the plug-in splitter or DC. Ingress present on one leg this amplifier would probably be viewable from the other test point, but at a reduced level. FNBs: Forward Path Input: Port 1 RF and AC separated. Port 1 Test Point (Bi-Directional) Diplex Filter Station Fwd EQ. Adjust for Tilt Station Pad. Adjust level Pre amplifier High pass filter Inter stage Compersator Inter stage EQ Pin Diode circuit Main Amplifier On output to Port 4.

Know your test equipment
Different test equipment operates differently. Size Matters!

How is a reference level determined?
From trunk return 52 dBmv max modem output 23db tap 2 dB drop loss 7 dB directional coupler The goal of reverse design is to keep the plant levels as high as possible to optimize C/I ratio. The levels are controlled by long loop AGC from the CMTS. The worst case will be from the high value taps because they have the most loss in the path from the house to the return active. The reference level inputs are calculated by finding the worst case signal loss from a transmitter in the home to the reverse input to a multi-port device. Modems put out 58 dBmv max. EXAMPLE: 26 tap 9 db for DC that feeds the modem 2 db drop loss Note, we did not consider cable loss. At the sub frequencies, this is minimal. Does your system use this as the reference point? 20dBmV at the reference point H L H L 23

ALIGNING THE RETURN PATH

Constant outputs in the return path?
L R R Return Equip. In the return path, signals originate at the customer drops and are transmitted back to the headend. In other words, many outputs feed one input. In this slide we can see that all amplifiers are receiving signals not only from one or more return amps, but from transmitters in the home as well. If all the return amplifiers are aligned to have constant outputs, the signal levels will vary widely by the time they get back to the headend. Of course this is unacceptable. Because of this, a different approach needs to be taken to the maintain the unity gain concept in the reverse path . If the return amplifiers were balanced with constant outputs, the levels would vary widely by the time they got back to the headend. This is due to return amplifiers having several inputs.

How does reverse sweep work?
The DSAM receives data from the transmitter and displays sweep from the headend unit 3. The field unit initiates the sweep through the return path at the reference level. 1. H L R R Return Equip. With this method the field unit injects a sweep signal into the return amplifier at the reference level. This sweep signal is essentially all frequencies in the return spectrum. The headend recognizes this sweep signal from the field unit, digitizes it’s own trace, and then sends it back out via the forward path to the field unit. The field unit detects the forward digital carrier from the headend unit and displays the results of the sweep trace at the headend. RF in FREQ CHAN ENTER FCN CLEAR help status alpha light abc def ghi jkl mno pqr stu vwx yz space +/- 1 2 3 4 5 6 7 8 9 x . FILE AUTO SETUP TILT SCAN LEVEL C/N HUM MOD SWEEP SPECT PRINT System Sweep Transmitter 3SR Stealth Sweep The headend unit receives the sweep from the field unit, digitizes it’s own trace, and sends out on a forward telemetry pilot. 2. RF out

Normalizing or Storing a Sweep Reference, reverse
H L R R Return Equip. With this method the field unit injects a sweep signal into the return amplifier at the reference level. This sweep signal is essentially all frequencies in the return spectrum. The headend recognizes this sweep signal from the field unit, digitizes it’s own trace, and then sends it back out via the forward path to the field unit. The field unit detects the forward digital carrier from the headend unit and displays the results of the sweep trace at the headend. RF in FREQ CHAN ENTER FCN CLEAR help status alpha light abc def ghi jkl mno pqr stu vwx yz space +/- 1 2 3 4 5 6 7 8 9 x . FILE AUTO SETUP TILT SCAN LEVEL C/N HUM MOD SWEEP SPECT PRINT System Sweep Transmitter 3SR Stealth Sweep Inject correct input sweep level Check for adjust raw sweep level Store reference file RF out

Continuing On Inject correct input sweep level
H L R R Return Equip. With this method the field unit injects a sweep signal into the return amplifier at the reference level. This sweep signal is essentially all frequencies in the return spectrum. The headend recognizes this sweep signal from the field unit, digitizes it’s own trace, and then sends it back out via the forward path to the field unit. The field unit detects the forward digital carrier from the headend unit and displays the results of the sweep trace at the headend. RF in FREQ CHAN ENTER FCN CLEAR help status alpha light abc def ghi jkl mno pqr stu vwx yz space +/- 1 2 3 4 5 6 7 8 9 x . FILE AUTO SETUP TILT SCAN LEVEL C/N HUM MOD SWEEP SPECT PRINT System Sweep Transmitter 3SR Stealth Sweep Inject correct input sweep level Use the reverse sweep reference to compare and adjust amplifier output levels RF out

Reverse Sweep Display Scale Factor Markers Start Frequency
Stop Frequency Marker Frequencies Max Variation within Frequency Range Marker Relative Levels

Fiber Optics

Loose Fiber Connector : A display an RF guy can understand
SC connector not pushed in all the way Before After This slide was provided by Jim Kuhns and he made the following statement. An SC connector that had not been pushed all the way in. The first picture has a wavy motion that rolls from left to right on the analyzer screen.

Cross section of an Single Mode optical fiber
Fiber Structure consists of a glass core, an outer protective glass cladding, and a buffer or coating Buffer Cladding Core 250 125 9 - What is fiber characterization? A series of tests to perform network base-lining on a fiber network. Fiber characterization mainly consists of the 5 following tests: - Optical Insertion Loss - Optical Return Loss - Optical Time Domain Reflectometry traces - Chromatic Dispersion testing - Polarized Mode Dispersion testing Side Front

Refraction Refraction is the bending of a ray of light at an interface. Cladding - What is fiber characterization? A series of tests to perform network base-lining on a fiber network. Fiber characterization mainly consists of the 5 following tests: - Optical Insertion Loss - Optical Return Loss - Optical Time Domain Reflectometry traces - Chromatic Dispersion testing - Polarized Mode Dispersion testing Core

IOR = Index of Refraction
The Velocity of light in glass is different than the velocity of light in a vacuum. This ratio is known as the Index of Refraction. n = c / v n = refractive index c = velocity of light in a vacuum v = velocity of light in glass Glass - What is fiber characterization? A series of tests to perform network base-lining on a fiber network. Fiber characterization mainly consists of the 5 following tests: - Optical Insertion Loss - Optical Return Loss - Optical Time Domain Reflectometry traces - Chromatic Dispersion testing - Polarized Mode Dispersion testing Vacuum

Reflection Reflection is the abrupt change in the
direction of a light ray at an interface. Cladding - What is fiber characterization? A series of tests to perform network base-lining on a fiber network. Fiber characterization mainly consists of the 5 following tests: - Optical Insertion Loss - Optical Return Loss - Optical Time Domain Reflectometry traces - Chromatic Dispersion testing - Polarized Mode Dispersion testing Core

Light in an optical fiber – Total Internal Reflection
If, for a moment, we could magnify a fiber and slow down the speed of light, we could visualize one pulse as it reflects off the core/cladding boundary. This is known as Total Internal Reflection Core - If we magnify a fiber for a moment and slow down the speed of light, we can visualize one pulse of light as it reflects off the core/cladding boundary. This is referred to as “total internal reflection” Magnified 25400x Timed slowed to 1 nanosecond Cladding

Bending Large noticeable bends and microscopic irregularities
can both attribute to loss in a fiber. Macrobending Microbending

Attenuation As the light signal travels down the fiber it decreases in power and is expressed in a rate of loss known as dB/km Cladding Cladding - What is fiber characterization? A series of tests to perform network base-lining on a fiber network. Fiber characterization mainly consists of the 5 following tests: - Optical Insertion Loss - Optical Return Loss - Optical Time Domain Reflectometry traces - Chromatic Dispersion testing - Polarized Mode Dispersion testing Core Core 100 km

Optical Return Loss = Optical Reflectance Loss
Excessive Reflectance or high Optical Return Loss (ORL) can decrease the performance of a transmission system, eventually damage the transmitter and increase noise. Cladding Cladding - What is fiber characterization? A series of tests to perform network base-lining on a fiber network. Fiber characterization mainly consists of the 5 following tests: - Optical Insertion Loss - Optical Return Loss - Optical Time Domain Reflectometry traces - Chromatic Dispersion testing - Polarized Mode Dispersion testing Core

Common Connector Types
SC Commonly referred to as Sam Charlie ST Commonly referred to as Sam Tom FC Commonly referred to as Frank Charlie LC Commonly referred to as Lima Charlie

Connector Configurations
PC or UPS vs APC SC - PC SC - APC

Inspect Before You Connectsm
Dave intros the webinar and intros me

Focused On the Connection
Bulkhead Adapter Ferrule Fiber Fiber Connector Alignment Sleeve Alignment Sleeve Physical Contact Fiber connectors are widely known as the WEAKEST AND MOST PROBLEMATIC points in the fiber network.

What Makes a GOOD Fiber Connection?
The 3 basic principles that are critical to achieving an efficient fiber optic connection are “The 3 P’s”: Perfect Core Alignment Physical Contact Pristine Connector Interface Light Transmitted Core Cladding CLEAN

What Makes a BAD Fiber Connection?
CONTAMINATION is the #1 source of troubleshooting in optical networks. A single particle mated into the core of a fiber can cause significant back reflection, insertion loss and even equipment damage. Visual inspection of fiber optic connectors is the only way to determine if they are truly clean before mating them. Light Back Reflection Insertion Loss Core Cladding DIRT

Illustration of Particle Migration
11.8µ 15.1µ 10.3µ Core Cladding Actual fiber end face images of particle migration Each time the connectors are mated, particles around the core are displaced, causing them to migrate and spread across the fiber surface. Particles larger than 5µ usually explode and multiply upon mating. Large particles can create barriers (“air gap”) that prevent physical contact. Particles less than 5µ tend to embed into the fiber surface creating pits and chips.

Types of Contamination
A fiber end-face should be free of any contamination or defects, as shown below: Simplex Ribbon Common types of contamination and defects include the following: Dirt Oil Pits & Chips Scratches

Contamination and Signal Performance
Fiber Contamination and Its Affect on Signal Performance 1 CLEAN CONNECTION Back Reflection = dB Total Loss = dB 3 DIRTY CONNECTION Clean Connection vs. Dirty Connection This OTDR trace illustrates a significant decrease in signal performance when dirty connectors are mated. Back Reflection = dB Total Loss = 4.87 dB

Test! Basic Tests Advanced Tests Visual Fault Locator (VFL)
Optical Insertion Loss Optical Power Levels Advanced Tests Optical Return Loss (ORL) Optical Time Domain Reflectometer (OTDR) Chromatic Dispersion (CD) Polarization Mode Dispersion (PMD) Optical Spectral Analysis (OSA)

Visual Fault Locator VFLs provide a visible red light source useful for identifying fiber locations, detecting faults due to bending or poor connectorization, and to confirming continuity. VFL sources can be modulated in a number of formats to help identify the correct VFL (where a number of VFL tests may be performed). FFL-100 FFL-050

Advanced Tests Optical Return Loss (ORL)
Optical Time Domain Reflectometer (OTDR) Detect, locate, and measure events at any location on the fiber link Fiber Characterization Determines the services that the fiber can be carry Basic tests plus: Chromatic Dispersion (CD) Polarization Mode Dispersion (PMD) Optical Spectrum Analysis (OSA) Spectral analysis for Wavelength Division Multiplexing (WDM) systems

T-BERD 4000 FTTx / Access OTDR
Introduction to OTDR It’s the single most important tester used in the installation, maintenance & troubleshooting of fiber plant Most versatile of Fiber Test Tools Detect, locate and measure events at any location on the fiber link Identifies events & impairments (splices, bends, connectors, breaks) Provides physical distance to each event/ impairment Measures fiber attenuation loss of each event or impairment Provides reflectance / return loss values for each reflective event or impairment Manages the data collected and supports data reporting. T-BERD 4000 FTTx / Access OTDR If you can only afford one piece of test gear in your network (and it’s not a small LAN), the OTDR is the tool you will need. It will do almost everything you need to fundamentally evaluate the fiber (except for advanced test, such as PMD, CD)

Background on Fiber Phenomena
OTDR depends on two types of phenomena: Rayleigh scattering Fresnel reflections. Light reflection phenomenon = Fresnel reflection Rayleigh scattering and backscattering effect in a fiber

How does it work ? The OTDR injects a short pulse of light into one end of the fiber and analyzes the backscatter and reflected signal coming back The received signal is then plotted into a backscatter X/Y display in dB vs. distance Event analysis is then performed in order to populate the table of results. OTDR Block Diagram Example of an OTDR trace OTDR’s are similar in principle to: Copper TDR Radar Sonar Shoot from one end collect reflected signal tie round trip time to one way distance.

Type of Fiber and Wavelengths
Single Mode (SM) 1310 & 1550nm are primary wavelengths used in SM OTDR measurements 1625nm is used in trouble-shooting when testing on active networks is needed Multimode (MM) 850 & 1300nm are dominant wavelengths used in MM transmission & testing 1490 FTTH operating wavelength We believe 1490 is an unnecessary expense (to OTDR at 1490) 1550 test wavelength is fully adequate to evaluate fiber for 1490 operation

Dynamic Range & Injection Level
Dynamic Range determines the observable length of the fiber & depends on the OTDR design and settings Injection level is the power level in which the OTDR injects light into the fiber under test Poor launch conditions, resulting in low injection levels, are the primary reason for reductions in dynamic range, and therefore accuracy of the measurements Effect of pulse width: the bigger the pulse, the more backscatter we receive The higher the dynamic range the further the OTDR will see. The higher the dynamic range, the more expensive the OTDR will be. For best value determine the right module for the job.

What does an OTDR Measure ?
Distance The OTDR measurement is based on “Time”: The round trip time travel of each pulse sent down the fiber is measured. Knowing the speed of light in a vacuum and the index of refraction of the fiber glass, distance can then be calculated. Fiber distance = Speed of light (vacuum) X time 2 x IOR Converts time (round trip time for signal to go out and backscatter return)

Attenuation (also called fiber loss) Expressed in dB or dB/km, this represents the loss, or rate of loss between two events along a fiber span The further the round trip of the backscatter the weaker the signal.. The X axis plots distance & Y axis plots dB signal level It appears logically as a decreasing signal left to right over distance.

Event Loss Difference in optical power level before and after an event, expressed in dB An event is either something that was placed on purpose (splice, connector) Or something that has happened to the fiber (bend) Depending upon the event, It’s going to look something like the above Fusion Splice or Macrobend Connector or Mechanical Splice

Reflectance Ratio of reflected power to incident power of an event, expressed as a negative dB value The higher the reflectance, the more light reflected back, the worse the connection A -50dB reflectance is better than -20dB value Typical reflectance values Polished Connector ~ -45dB Ultra-Polished Connector ~ -55dB Angled Polished Connector ~ -65dB Reflectance relates to a specific event . This is especially critical in high speed networks (10G+) Or in applications that use high power lasers (RF Video overlay in FTTH) Reflectance can cause signal degradation and needs to be managed.

Optical Return Loss (ORL) Measure of the amount of light that is reflected back from a feature: forward power to the reflected power. The bigger the number in dBs the less light is being reflected. The OTDR is able to measure not only the total ORL of the link but also section ORL Attenuation (dB) ORL is similar to reflectance, but instead of a single event, ORL is a measure of a section or span of overall reflected signal. ORL of the defined section Distance (km)

Optical Return Loss (ORL)
Light reflected back to the source PAPC PPC PT PF Light Source Photo- diode Optical return loss is the ratio of the output power of the light source to the total amount of back-reflected power (reflections and scattering). It is defined as a positive quantity. Reflectance (dB) is the ratio of reflected power to incident power due to a single interface. It is defined as a negative quantity PT: Output power of the light source PAPC: Back-reflected power of APC connector PPC: Back-reflected power of PC connector PF: Backscattered power of fiber PB: Total amount of back-reflected power ORL (dB) = 10Log > 0

Effects of High ORL Values
All laser sources, especially distributed feedback lasers, are sensitive to optical reflection, which causes spectral fluctuation and, subsequently, power jitter. Return loss is a measure of the amount of reflection accruing in an optical system. A -45dB reflection is equivalent to 45dB return loss (ORL). A minimum of 45-50dB return loss is the industry standard for passive components to ensure normal system operation in singlemode fiber systems. Increase in transmitter noise Reducing the OSNR in analog video transmission Increasing the BER in digital transmission systems Increase in light source interference Changes central wavelength and output power Higher incidence of transmitter damage The angle reduces the back-reflection of the connection. SC - PC SC - APC

Optical Return Loss Ratio between the transmitted power and the received power at the fiber origin 2 different test methods: Optical Continuous Wave Reflectometry (OCWR): A laser source and a power meter, using the same test port, are connected to the fiber under test. Optical Time Domain Reflectometry (OTDR) The laser source sends a signal at a know power level into the fiber, and the power meter measures the reflected power level at the same location. OCWR method OTDR method ON/ OFF Backscatter

CW Stabilized Light Source
ORL Measurement Methods Optical Continuous Wave Reflectometer Accuracy (typ.) ± 0.5dB Typical Application - Total link ORL & isolated event reflectance measurements during fiber installation & commissioning Strengths - Accuracy - Fast & real time info - Simple & easy results (direct value) Weaknesses - No localization CW Stabilized Light Source Process Controller Coupler Display Termination Plug Power Meter Optical Time Domain Reflectometer Accuracy (typ.) ± 2dB Typical Application - Perfect tool for troubleshooting- Spatial characterization of reflective events & estimation of the partial & total ORL Strengths - Locate reflective events - Single-end measurement Weaknesses - Accuracy - Long acquisition time Pulsed Light Source Process Controller Coupler Display Photodetector

How to interpret a trace
OTDR Events How to interpret a trace

How to interpret an OTDR Trace
Do step you through interpretation of an OTDR trace, we’re going to utilize content from one of our Wall posters we’ve recently developed. It’s called “Undersanding OTDRs”. ILater in the Webex we’ll show you how you can get your own poster. So here you see an OTDR trace w/ lots of “events”. Let’s take a closer look at each one.

Front End Reflection Connection between the OTDR and the patchcord or launch cable Located at the extreme left edge of the trace Reflectance: Polished Connector ~ -45dB Ultra-Polished Connector ~ -55dB Angled Polished Connector up to ~ -65dB Insertion Loss: Unable to measure At the very beginning of the OTDR trace you see the first connection.(reflective) Notice the spike (reflection) then a drop back down to a steady signal level.

Dead Zones Attenuation Dead Zone (ADZ) is the minimum distance after a reflective event that a non-reflective event can be measured (0.5dB) In this case the two events are more closely spaced than the ADZ, and shown as one event ADZ can be reduced using shorter pulse widths Event Dead Zone (EDZ) is the minimum distance where 2 consecutive unsaturated reflective events can be distinguished In this case the two events are more closely spaced than the EDZ, and shown as one event EDZ can be reduced using shorter pulse widths At some point you’ve probably heard people talk about dead zones. Where w/ your mobile phone, a dead zone is a spot where you can’t hear, an OTDR dead zone is an area where you cannot see true signal. It’s caused by reflective events (connector, mechanical splice) Within the definition of Dead Zone, there are two categories: ADZ & EDZ (above)

Connector A connector mechanically mates 2 fibers together and creates a reflective event Reflectance: Polished Connector ~ -45dB Ultra-Polished Connector ~ -55dB Angled Polished Connector up to ~ -65dB Insertion Loss: ~ 0.5dB (loss of ~0.2dB w/ very good connector) A connector causes a reflection (air gap) which. An angled connector will have a much lower spike than a non-angled (PC type)

Fusion Splices A Fusion Splice thermally fuses two fibers together using a splicing machine Reflectance: None Insertion Loss: < 0.1dB A “Gainer” is a splice gain that appears when two fibers of different backscatter coefficients are spliced together (the higher coefficient being downstream) Fusion splices are the standard method of splicing fibers today. You won’t see them as much in LANs as you will in public networks.due to distances. Reflectance: None Insertion Loss: Small gain

Fusion Splices Direction A-B Direction B-A
Biggest chalenge w/ OTDR’s here is getting the loss of the event accurate. If you need optimum accuracy you’ll need to shoort both directions. Bi directional measurements also emiminate gainers.

Macrobend Macrobending results from physical bending of the fiber.
Bending Losses are higher as wavelength increases. Therefore to distinguish a bend from a splice, two wavelengths are used (typically 1310 & 1550nm) Here we’re only covering Macrobends; but… You’ll also here the two terms Macrobend & Microbend - Same result, but different causes… Macrobending loss refers to loss from physical bending of the fiber Microbending loss is caused by pressure resulting in changing the physical shape fo the glass at a particular spot (core deformation) Reflectance: None Insertion Loss: Varies w/ degree of bend & wavelength

Mechanical Splice A Mechanical Splice mechanically aligns two fibers together using a self-contained assembly. Don’t see too many of these anymore. Looks like a connector because it’s a mechanical connection w/ an air gap. This has been replaced for the most part by the fusion splice. Reflectance: ~ -35dB Insertion Loss: ~ 0.5dB

Fiber End or Break A Fiber End or Break occurs when the fiber terminates. The end reflection depends on the fiber end cleavage and its environment. Reflectance: PC open to air ~ -14dB APC open to air ~ - 35dB Insertion Loss: High (generally) An OTDR cannot tell you whether the end of the fiber is the real end or a cut or break. The signals look the same, so here you have to use your knowledge of the network. ”How long is it supposed to be?” “ “Am I shooting the correct fiber?”

Ghosts A Ghost is an unexpected event resulting from a strong reflection causing “echos” on the trace When it appears it often occurs after the fiber end. It is always an exact duplicate distance from the incident reflection. Ghosts are what they sound like (unless you believe in Ghosts) The are artifacts that show up on the trace that aren’t really there. But you can spot a ghost if you know what to look for… Now OTDRs have Ghost detect features that you can use to help identify them. Reflectance: Lower than echo source Insertion Loss: None

Typical Attenuation Values
0.2 dB/km for singlemode fiber at 1550 nm 0.35 dB/km for singlemode fiber at 1310 nm 1 dB/km for multimode fiber at 1300 nm 3 dB/km for multimode fiber at 850 nm 0.05 dB for a fusion splice 0.3 dB for a mechanical splice 0.5 dB for a connector pair (FOTP-34) Splitters/monitor points (varys with component)

Monitoring the Reverse Path Inside Plant

Major Operational Challenges
Plant Certification and Maintenance: Elevate plant performance to ensure reliable service HFC: Sweep & advanced return path certification Metro Optical: Fiber and transport analysis Monitor Performance: Continuously monitor the health of your upstream and downstream carriers Proactively identify developing problems before customers do Monitor both physical HFC & VoIP service call quality Utilize advanced performance trending and analysis to prioritize Get Installations Right the First Time Improve installation practices to prevent service callbacks & churn Verify physical, DOCSIS® and PacketCable performance Drive consistency across all technicians Troubleshoot Fast: When issues occur, find and fix fast Isolate and segment from NOC, dispatch right tech at right time Field test tools that can find problems and verify fix

Return Path Monitoring Benefits
Troubleshoot nodes faster to reduce MTTR and increase workforce efficiency Identify impairments before rolling a truck using both spectrum and packet monitoring technology Use field meters to quickly locate ingress, the most common impairment View performance history to understand transient problems to roll a truck at the right time to find and fix the issue Reduce trouble tickets and customer churn by identifying problems before your subscribers Rank nodes using convenient web-based reports for proactive maintenance Easily and quickly detect impairments such as fast impulse noise, ingress, CPD, and laser clipping on all nodes 24/7 View live spectrum, QAMTrak™ analyzers and a wide array of reports conveniently via the web

DOCSIS® 3.0 adds Capability to Bond up to 4 Upstream 64QAM Carriers!
Four times 6.4 MHz = 25.6 MHz! (without guard-bands) Increased chances for laser clipping Increased probability of problems caused by ingress, group delay, micro-reflections and other linear distortions Inability to avoid problem frequencies such as Citizens’ Band, Ham, Shortwave and CPD distortion beats Where are you going to place your sweep points?

Live Spectrum Display Remember only 2 people on the same RPM card at the same time and only 2 people on the same port at the same time. Discuss left side controls Discuss controls at the top of the screen including Spectrum analyzer settings Zero span Reference Levels

Choose a carrier for QAMTrak
First thing that needs to be done besides choose a node is to choose which upstream carrier for viewing

Getting To Know The QAMTrak Analyzer
QAMTrak Sections Impairment Dashboard Impairment Charts FFT Spectrum Display Constellation Strip Chart Data Tables Control/Information Bar

QAMTrak Analyzer: Primary Sections
Impairment Dashboard The top 3 selections show the health of the system; the bottom 6 show the impairments and frequency of the impairments Display in simple red light / green light format which impairments have violated admin-defined thresholds and what % of packets affected by each (rollup status) Shows min/max/average for health metrics and impairments Provides single-click launch points to detailed charts for each impairment type

Impairment Dashboard – Two Main Sections
Top three boxes indicate HFC health Is data corruption occurring within packets being demodulated? How tight are the constellation points before CMTS compensation How well is the CMTS likely able to compensate for impairments present Bottom six boxes indicate how frequently each impairment type is occurring How often does a packet come across which violates threshold? What is min/max/average for each impairment type? Which impairment(s) are my biggest problem right now? Clicking any button will launch a maximized impairment chart window within the QAMTrak Analyzer

Impairment Dashboard – General Interpretation
Impairment/Health Metric Label Rollup Counter Percent of packets since start of QAMTrak session which have violated admin defined threshold for that impairment or metric Session Status (Background Color) Indicates whether impairment threshold has been violated during session Latest Value Value for last packet demodulated or current packet highlighted for historical packet analysis Latest Status Pass/Fail status for last packet demodulated or current packet highlighted for historical packet analysis ( or ) Min/Max/Average Minimum, Maximum, Average values for all packets captured during current QAMTrak session or since last reset Caveats: Only the latest 600 packets are displayed on strip chart and in tables Min/Max/Average and Rollup Counter can reflect packets which are not visible in strip chart of tables for sessions with >600 packets captured!

Primary Impairments Impairment Dashboard Impairment Charts
Provides detailed display for five primary impairment types plus codeword error strip chart – supplement Impairment Dashboard Charts update for each packet in live mode or historical packet review mode Y-Axes can be manually rescaled or auto-scaled, charts can be resized, many other options available through Flash interface

Primary Measurements Impairment Dashboard Impairment Charts FFT Spectrum Display Provides Spectrum Analyzer display without opening a separate window FFT-based spectrum analyzer – will look different than standard PathTrak SA Display will show what spectrum looked like at time of packet capture when reviewing captured packets in paused mode

Upstream Constellation
Impairment Dashboard Impairment Charts FFT Spectrum Display Constellation Can display Equalized, UnEqualized symbol locations, or both Can show latest packets, all historical packets, or both Displays constellation packet by packet when reviewing historical packets

Impairment Dashboard Impairment Charts FFT Spectrum Display Constellation Strip Chart Separate chart traces for Equalized MER, Unequalized MER, and Carrier Level (on second Y-Axis) Detailed packet info available using hover function Can use arrow keys to review historical packets one at a time

Impairment Dashboard Impairment Charts FFT Spectrum Display Constellation Strip Chart Data Tables Users can toggle between strip chart, all-packet data table, and unique MAC data table Tables are sortable by all rows, can be exported to .csv file Data can be copied from tables to clipboard for pasting into other apps

PathTrak WebView Code Word Errors CPE MAC Address
The user can also place all metrics on the same page CPE MAC Address

PathTrak WebView QAMTrak
CPE MAC Address Codeword Error Detection Equalized and UnEqualized MER Micro-reflections In Band Response – Ripple Group Delay Ingress Under the Carrier Impulse Noise Detection

DOCSIS Downstream Codewords
122 of each RS codeword’s 128 symbols are data symbols, and the remaining six are parity symbols used for error correction. ITU-T J.83, Annex B states that the data is “…encoded using a (128,122) code over GF(128)…” which shows each RS codeword consists of 128 RS symbols (first number in first parentheses) and the number of data symbols per RS codeword is 122 (second number in first parentheses), leaving six symbols per RS codeword for error correction. DOCSIS downstream RS FEC is configured for what is known as “t = 3,” which means that the FEC can fix up to any three errored RS symbols in a RS codeword.

Downstream Monitoring

The Cable Video Network
Video Passes Through Four Separate Operational Layers Before it Reaches the Home. MPEG Headend Master/Super Headend IP Transport Hub/HFC Home Origination and processing Transport through the IP network MPEG edge-processing RF combining Distribution over HFC Inside Plant Outside Plant Off-air Ingest VOD Combiner DPI STB IP L2/L3 Core Network MPEG Mux. Modem Encryption Modulation Phone Purpose here is to illustrate the evolution of video monitoring for cable, highlight how JDSU arrived at the edge, and why this is the critical segment for monitoring. 4 Segments are Ingest/Super Head-end, Backbone, Edge Head-end, HFC/Outside Plant Early on, Video Monitoring in cable was driven by a corporate desire for “end to end” visibility of video services. Corporate owned the backbone portion of the network, and the early video monitoring solutions catered to this segment. The other “end” was then served by sticking light-duty probes at the egress of the edge headends. Net Result was limited visibility to the most critical element… In Backbone, pretty much only two things that can hurt video – IP packet loss or IP delays. These are fundamentally ethernet functions – no real value to deep service layer monitoring as nothing happens there. Cable continues to push video technology to the edge – this is where MPEG services are manipulated, massaged and processed. This is where visibility is most needed, but monitoring deep mpeg is complex and until recently, there was no cost-effective way to get deep 24/7 visibility. AT JDSU, we’ve been converging on the edge headend for years. With the Wavetek line we’ve always served the last segment – the HFC and outside plant – by providing RF engineers and techs with meters and more recently the RSAM for monitoring the RF at the combiner. On the inside plant side, our MPEG analyzer provide much needed visibility and troubleshooting for the MPEG elements in the head-end. Transition: In the original “end-to-end” diagram, the edge headend was a single node. In actuality there is a chain within the headend where MEPG streams are manipulated – isolating problem sources requires visibility between these devices. This is troublshooting need that JDSU has been serving for years with our MPEG analyzers. CMTS PC But The MPEG Edge is the most critical layer and poses the most significant risk to video quality.

The RF edge is home to the most complex equipment in the network
Current monitoring solutions focus on the national backbone and on validating the content when programming first enters the network. Often QoS issues (like tiling) are introduced by the complicated equipment at the network edge If you aren’t monitoring at the RF edge, only the subscriber will have visibility to the impairments You’ve caused these problems, but you don’t see them Troubleshooting is initiated by a customer complaint and without this “edge” visibility you may spend multiple truck rolls and weeks isolating the source. MPEG edge-processing RF combining Off-air Ingest Combiner DPI MPEG Mux. Encryption Modulation CMTS

And currently this is the last place you’re monitoring the video?
Often QoS issues are introduced by the complicated equipment at the network edge Local Off-Air Ingest: Provider issues Antennas 8VSB Receivers Muxes to groom for regional networks Program Insertion: Quality of ad being spiced PCR Discontinuity Decoding/Timing of DPI information MPEG edge-processing RF combining Encryption: Encryption not-enabled Equipment configuration Multiplexing: Streams from regional networks Grooming Transrating Over-compression Equipment configuration Off-air Ingest Combiner DPI Modulation: MPEG to RF Equipment configuration Oversubscription MPEG Mux. Encryption Modulation CMTS RF Combining: Poor cabling Poor Isolation Loose connectors Driver/Isolation amp issues And currently this is the last place you’re monitoring the video?

You may already have monitoring…
Outside Plant CMTS STB Phone PC Modem DPI MPEG Mux. Encryption Modulation IP L2/L3 Core Network VOD Combiner Inside Plant Off-air Ingest IP monitoring IP monitoring … but your customers are still seeing issues Content monitoring has traditionally been expensive. Typically deployed only where content enters the network. Content Monitoring is typically not deployed at the very edge of the network That leaves the most vulnerable spot in the network, in the dark

Detailed MPEG analysis detects the important issues
Video/Audio QoS issues caused by equipment in the headend or local network are transport related and can be identified without performing content analysis Video freeze result of lost programs or video PIDs Audio loss as a result of missing audio PIDs Other frozen/black/no-audio that are the result of content (and not the programs) in almost all cases isn’t anything local system personnel can do anything about. Content analysis also limited to unencrypted programming – preventing use at edge of the network. Content analysis is impractical and costly at the edge of the network. Investment is significantly more effective if focused on transport tools that provide complete visibility and troubleshooting directly at the edge modulator.

Get complete visibility – “Wrap the Edge”
Video Monitoring is a video monitoring solution optimized for the network edge MVP-200 probe (full line-rate MPEG over GigE) RSAM probe (Digital video RF, Analog video RF, DOCSIS) PVM – Simple, lightweight, centralized system to tie it all together. Origination and processing Transport through the IP network MPEG edge-processing RF combining Distribution over HFC Inside Plant Outside Plant Off-air Ingest VOD Combiner DPI STB IP L2/L3 Core Network MPEG Mux. Modem Encryption Modulation Phone CMTS PC MVP-200 MVP-200 RSAM

Example – Tiling The RF probe consistently reported Continuity error alarms on a QAM. This clip shows what your Customer experienced the impact of these CC errors

Another Example - Video Freeze
Click on video to play How do you explain this to your customer?? Below are the alarms generated for the above event from the MVP: Event Starts - Minor Continues - Major HLN_13 (27) MVP Trap QAM 28 OUTPUT Trap Console received trap traps/event. Time: January 6, :03:10 AM EST STB: 27 PID ID: -1 PID: -1 PID Type: Event ID: programLost Event Severity: minor From MVP: Card: 2 Source IP: XX :60000 Dest. IP: XXX :28115 Ends - Clear HLN_13 (27) MVP Trap QAM 28 OUTPUT Trap Console received trap traps/event. Time: January 6, :03:17 AM EST STB: 27 PID ID: -1 PID: -1 PID Type: Event ID: programLost Event Severity: major From MVP: Card: 2 Source IP: XX :60000 Dest. IP: XXX :28115 HLN_13 (27) MVP Trap QAM 28 OUTPUT Trap Console received trap traps/event. Time: January 6, :03:21 AM EST STB: 27 PID ID: -1 PID: -1 PID Type: Event ID: programLost Event Severity: clear From MVP: Card: 2 Source IP: XX :60000 Dest. IP: XXX :28115

Knowing is only half the battle…
Monitoring tells you when you have a problem. To isolate the problem source, the ops staff needs troubleshooting tools as well. Remote access via PVM gives service level visibility at the edge of your network, from anywhere. Critical in digital video, where problems are intermittent and spurious. Critical at the edge, where staff may be hours from the equipment. JDSU’s monitoring probes are unique in providing integrated real-time analyzers for troubleshooting. Troubleshoot anytime, anywhere.

Video Monitoring Application
Identify and segment problems using intuitive displays RF or MPEG? Outside plan, headend or source issue Widespread or localized? Intermittent or persistent problem? Find root-cause with advanced troubleshooting Click an event or status bar to get a live display Capture transport streams to share with your network equipment suppliers View table decodes to understand impairments Access Historical PM Reports NetComplete Per Program, Per Node Worst Offenders Key Performance Indicators A source issue means it is coming into the headend bad, so it could be a transport problem, a problem with the content from the provider or a problem in the master headend. Basically it is not a problem created in this headend is the important thing to understand.

Network Management System Integration
SNMP and XML API: Designed to be flexible and easily integrated Per Program and Per Stream, real-time data Real-time per program status to one system view We can integrate with whomever whenever. We recognize that our customer already have management platforms in place, and do not want to have to deal with yet another monitoring platform. The MVP-200 was designed to be flexible and agnostic to the management system above it. We are a fact finder and truth seeker. Our job is to report on the MPEG services, and provide accurate information to the management platform. NO intermediary layer required! No need for a server to take our probe data and intrepret it. No need to deploy our own management system. Buy one MVP-200, buy 100 MVP-200’s, and plug them right into your existing management platform. Note that this slide has been very successful at getting customer’s engaged about the MVP-200 potential. This slide is Miranda’s iControl integration of the MVP The network model on top has block elements for the NEM equimpent – Cisco routers and SEM’s here. Prior to our MVP-200, Miranda could easily display diagnostics from those elements, and could monitor the physical layer, but had no fault management options for the programs at the MPEG Service layer. Once we were integrated, they got the bottom portion operational. All of the green “chicklets” on the bottom are real-time, per program statuses being provided by the MVP-200. Customizable alarm settings on a per program basis – SNMP interface. They can launch the MVP-200 GUI remotely for troubleshooting programs, with no impact to the monitoring done here. This is a good slide to end on – it’s repeated at the end of the deck.

Solve real problems today
Why Video Monitoring? Solve real problems today Optimized for an operations staff Real-time alarming direct to local staff Complete RF component for analog, digital and DOCSIS Cost-Efficient Fraction of the cost of conventional content monitoring Proximity to the Edge Monitor right at hand-off to access network, visibility for entire digital network Isolate problem sources Integrated remote analyzers at IP and RF

Thank You

Plant Reliability Larry Jump JDSU Field Applications Engineer

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