Ensuring Cabling Performance in the Customer-Owned Outside Plant

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Nathaniel Randall
5 years ago
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1 Ensuring Cabling Performance in the Customer-Owned Outside Plant

2 Needs to be able to qualify the installation to validate bandwidth requirements are met Future high bandwidth applications Future Proof Fiber has virtually unlimited bandwidth The transmitter and receiver determine the data rates Outside plant networks require low reflectance terminations Photo: Versitron

3 Methods for Terminating cables in the outside plant: 1. Mechanical splicing 2. Polishing 3. Pre-polished mechanical connector 4. Splicing pre-terminated patch cords 5. Fusion splicing using Splice on Connectors (SOC)

45dB) Long term reliability issues Polishing: Time consuming and hard to do in the field High

4 Mechanical splices: Have inconsistent performance, sensitive to vibration Requires matching gels High return loss, limits bandwidth High insertion loss (0.45dB) Long term reliability issues Polishing: Time consuming and hard to do in the field High return loss (30dB), high insertion loss (0.5dB) Subject to technician ability Photo: Shenzhen G-Tech Communication Photo: Network Cabling Help

Not suitable for outdoor installations Splicing pre-terminated patch cords Requires a splice tray

5 Mechanical Connector Bandwidth limiting due to return loss Long term reliability issues Requires fiber end to be cleaved Up to five attempts? Use a VFL to qualify? Not suitable for outdoor installations Splicing pre-terminated patch cords Requires a splice tray Approximately the same cost as splice on connectors Requires that both fiber ends be cleaved Photo: Fiber Instrument Sales Photo: Fiber Instrument Sales

6 Splice on Connectors Available in SC, LC, FC, ST No crimping, epoxies, matching gels Faster installation More reliable installation Photo: Greenlee Communications

7 Splice on Connectors Low insertion Low return loss Splice protection sleeve is located in the strain relief No splice tray is required Pre-cleaved fiber ready for splicing Pre-polished fiber termini Splice protector located in strain relief

8 Splice on Connector Mounted in Fusion Splicer 900u Fiber Adapter SC/UPC SOC in Universal Holder Electrodes

9 Cost Analysis: Splice on Connector Connector $9.00* Labor (20 splices per hour) $2.75 Total Cost $11.75 Mechanical Connector Connector $12.00* Labor (25 terminations per hour) $2.20 & VFL Testing Total Cost $14.20 $55/hour

10 Splice on Connectors meet the following standards: ANSI/TIA-568-C.3 TIA-604-FOCIS Telcordia GR-326-CORE

Fusion Splicing: Splicing provides consistent results for high bandwidth applications Low amount of technician training required, simple user interface Excellent return

11 Fusion Splicing: Splicing provides consistent results for high bandwidth applications Low amount of technician training required, simple user interface Excellent return loss, typically >60dB Excellent insertion loss, typically 0.02dB SMF and 0.01dB MMF Removable holders allow for SOC Splicing time = 9s fiber stripping takes all of the time!

Core alignment vs V-Groove Lower splice losses due to active alignment Two cameras and six motors align the fiber core not the outside diameter of the fiber Compensates for

12 Core alignment vs V-Groove Lower splice losses due to active alignment Two cameras and six motors align the fiber core not the outside diameter of the fiber Compensates for fiber concentricity Compensates for cladding diameter differences Each fiber manufacturer will have slightly different geometries Old fiber especially problematic Courtesy: Corning

13 Core alignment vs V-Groove Compensates for dirt in V-Groove Compensates for V-Groove damage and misalignment Even the same fiber cut and re-spliced will have higher losses since the V-Groove splicer does not know where the core of the fiber is!

clean both ferrule and bulkhead Photo: Courtesy

14 Connectors must be CLEAN! Dirty connectors can cause: Complete failure Cross contamination Reduce bandwidth Permanent damage Reel type of cleaners work well Pens can clean both ferrule and bulkhead Photo: Courtesy Cletop Photo: Courtesy Greenlee Communications The technician will use the pens!

the cleaning platform The end face is cleaned

15 Combination Cleaning Process cleans the complete end face of the widest range of debris and contamination A small amount of precision fiber optic cleaner is placed in one corner of the cleaning platform The end face is cleaned and dried in one straight-line motion Courtesy: Chemtronics

16 Fiber Scopes: Inspect Clean if Necessary Inspect Then Connect Replace if Necessary Validate that connector is clean Micron resolution Field of View most important specification must be able to view outside of the four zones Contamination can migrate with vibration

17 Fiber Scopes: PASS/FAIL to IEC Wireless hotspot created for interface to smart phones

18 Connector Zones:

19 Single-Mode Criteria Table Zone Description Diameter Allowable Defects (Dia) Allowable Scratches (Width) A Critical Zone 25um None visible at 200X None visible at 200x B Cladding Zone 25 to 120um Any < 2um None >3um Total of five 2um - 5um None > 10um C Adhesive Zone 120 to 130um None > 10um Any scratch OK D Contact Zone 130 to 250um None > 10um Any Scratch OK

20 Manual OLTS Measurements: Measure insertion loss of the fiber link Return loss not measured Laser Source (GDLS 350) Optical Power Meter (GRP 460)

21 Insertion Loss Measurements using a handheld laser and power meter Zero the power meter Insert the DUT and measure the IL Measurement Qualit y Jumper 0.00dB

22 Typical Report: Test data Time stamp Description PDF Report

Fully Automatic Optical Loss Test Set (OLTS) One OLTS unit on each end of the fiber link AutoTest button provides single button operation RL and IL is measured

23 Fully Automatic Optical Loss Test Set (OLTS) One OLTS unit on each end of the fiber link AutoTest button provides single button operation RL and IL is measured bi-directionally at all wavelengths The location of the losses is not measured OLTS can also be used as a standalone power meter and laser source Reporting/documentation software is provided

24 OLTS Results Pass/Fail reporting Bi-directional measurement of insertion loss from A to B and B to A for a patch cord Summary page shows the insertion loss and return loss results for the entire link

Optical Time Domain Reflectometer (OTDR) Single ended measurement Locates individual insertion and return losses in the fiber link Full reporting for compliance and later during

25 Optical Time Domain Reflectometer (OTDR) Single ended measurement Locates individual insertion and return losses in the fiber link Full reporting for compliance and later during troubleshooting Auto shutdown feature so that live fibers are not interrupted Out of band testing is available to test live fibers at 1625nm Bi-directional measurements Macrobend analysis 930XC OTDR

26 Laser Probe pulse End of fiber Display Processor Coupler Detector Fiber under test Rayleigh backscatter Fresnel reflection The Optical Time Domain Reflectometer (OTDR) is an instrument that uses the inherent backscattering properties of an optical fiber to detect faults and categorize its condition. The OTDR sends high-power pulses of laser light down the fiber and captures the light that is reflected back (much like a radar system). By measuring the timing and power levels of the return pulses, the instrument correlates the reflected information with physical locations along the fiber and displays a trace that shows optical power versus distance. Attenuation of the fiber is displayed as the slope of the trace. Interruptions such as splices, connectors, bends, breaks or flaws in the fiber appear as transitions ( events ) that represent their nature and location.

27 Optical Time Domain Reflectometer (OTDR) Key Specifications Dynamic range; typically 32-38dB for handheld; 42dB+ for tablet Higher dynamic range will allow the technician to probe longer fibers or fibers with high loss events Dynamic Range is quoted at the widest pulse width, this results in the poorest resolution. Event Deadzone; typically 1-2m The ability of the OTDR to resolve between two reflective events such as poor connectors and over-layed fiber events Resolution is quoted at the narrowest pulse width, this results in the poorest dynamic range. Attenuation Deadzone; typically 4m The ability of the OTDR to measure a backscatter event (fusion splice) after a reflective event.

28 OTDR Trade-offs - Pulse Width Larger pulse width (more energy into the fiber) Longer distance measured Results in lower resolution Smaller pulse width (less energy into the fiber) Shorter distance measured Results in higher resolution

29 OTDR Trade-offs - Averaging Longer averaging time Best signal to noise Shorter averaging time Lower signal to noise

30 Typical OTDR Trace using Trace Viewer Software: OTDR Bulkhead *Reflective Event (not a splice) Cursors End of Fiber Some light is reflected back from the bad connection The reflected light hits the laser and is then transmitted again as signal but it is really noise (ghosting) A ghost (not real ) of the original reflection will be at 2X the original reflection Reflections will limit the bandwidth of fiber links due to ghosting effects!

31 Mechanical connector with high loss (but passes mechanical connector specification) and high reflection Mechanical connectors can move and change loss The insertion loss is <0.75dB but the return loss is > -40dB Courtesy Greenlee Communications

32 Fusion splice measurement Fusion Splice

33 Fusion splice measurement Fusion Splice = 0.048dB The return loss was not measureable!

34 SUMMARY Splice on connectors provide zero return loss/low IL Short ROI on fusion splicer when using SOC Fusion splicing dramatically improves network performance Mechanical connectors limit bandwidth due to ghosting effects and losses Effective cleaning prevents IL and damage Effective use of an OTDR allows the technician to quickly find faults

35 Greenlee Communications 1390 Aspen Way Vista, CA,

Ensuring Cabling Performance in the Customer-Owned Outside Plant. Keith Foord Product Manager Greenlee Communications

Ensuring Cabling Performance in the Customer-Owned Outside Plant Keith Foord Product Manager Greenlee Communications Introduction: Outside plant fiber networks require low reflectance terminations for