Installation & Maintenance Testing for FTTx Passive...
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Installation & Maintenance Testing for FTTx Passive Optical Networks ANMTA Fall Conference Tucson, AZ October 2016
Transcript of Installation & Maintenance Testing for FTTx Passive...
Installation & Maintenance Testingfor FTTx Passive Optical Networks
ANMTA Fall ConferenceTucson, AZ
October 2016
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● Introduction● FTTx Passive Optical Network (PON) Overview● FTTx PON End-to-End Loss Test – Construction Phase● FTTx PON OTDR Test – Construction Phase● FTTx PON In-service Tests PON Power Meter – Verifying Transmit & Receive power levels In-service PON OTDR test – Fault-locating an in-service PON Active ONT Identifier
● Connector Cleaning and Inspection
Presentation Agenda
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● Audience background to help focus the presentation: How many have experience installing or maintaining fiber optic
networks? What network architectures have you deployed?
– Fiber-to-the-Home (FTTH) PON?– Fiber-to-the-Curb (FTTC) PON with coax/copper drops?– HFC point-to-point fibers feeding tree-and-branch coax network?
How many have used Source and Power Meter to measure optical loss or attenuation?
How many have used an OTDR to:– Trace a fiber?– Measure distance and loss to fiber end?– Locate & measure loss & reflectance of connectors or splices?
Introduction
GPON or EPON FTTH Architecture
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GPON / EPON deliver voice, Internet & video to homes
ONT
OLT
FDH
AccessTerminal
PON Splitter
Locatedat FDH…
…and/orAccess
Terminal
Central Office /Local Exchange
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● Optical Distribution Network (ODN) includes: WDM Mux/Demux at Headend Optical distribution fiber (feeder fiber) Passive Splitter (or cascaded splitters) Customer Drop Fibers
RFoG PON Architecture
Source: Aurora Networks
Headend
R-ONU
ODN
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● Optical Light Source (OLS): Injects known amount ofoptical power (CW or tone) into an FTTH network fiber
Optical Power Meter (OPM): Measures receivedoptical power at the output of an FTTH network fiber
● Optical Time Domain Reflectometer (OTDR): Works like an optical radar to detect connectors, splitters, and fiber ends in FTTH networks
Optical Fiber Identifier (OFI): Clips onto a fiberto detect active fibers (without disrupting service), inactive fibers, or fibers carrying a test tone
● Visual Fiber Identifier (VFI): Injects visible red light intooptical fiber for tracing fibers inside CO or building
Equipment Used to Test FTTx PONs
Measure Loss using an Optical Light Source + Optical Power Meter
Measuring Optical Loss (Attenuation)
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1) Set reference
Light Source
Tx
Optical PowerMeter
Rx
Tx cordPIN = -20 dBm
Measure PIN and store it as the 0 dB reference level.
0 dB
Rx cord
Connection (two connectors matedthrough an adapter)
Tx
Optical PowerMeter
Rx
Light Source
2) Check test cords
Tx cord
Allowed insertion lossdepends on connector type.
0.4 dB
Measure Loss using an Optical Light Source + Optical Power Meter
Measuring Optical Loss (cont.)
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Rx
Optical PowerMeter Light Source
Tx
In this example:IL = -20 dBm - (- 22 dBm) = 2 dB
POUT = -22 dBm
3) Measure link insertion lossMeasure POUT and calculate IL = PIN – POUT.
2.0 dB
LinkPIN = -20 dBm
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● Use Source (OLS) & Power Meter (OPM) to measure loss Use OLS to inject light at known power level into one end Use OPM to measure output light at other end OPM displays loss in dB Loss testing done during Construction phase
Construction Phase Loss Test
Video Serving Office (VSO)
CustomerPremises
OLT
Feeder
Distribution
DropCWDM
FDF
Feeder Splitter Distribution Drop
20 km reach typical
1490 nm1310 nm
1550 nm ONT CATV Video
Optional
Outside Plant
FDH
InjectKnownPower
MeasureLoss
MeasureLoss
OLS7OPM4
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Loss Measurement using OLS + OPM
Power (dBm)
Distance
? IL (dB)
PIN
POUT
An OLS/OPM can only measure end to end loss. If loss is excessive, how can one determine cause?
Actual
Expected
Distance
RelativePower(dB)
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● An OTDR is a one-dimensional optical “radar” Injects pulses of light, measures the amplitude and time of flight of
backscattered and reflected light guided back up the fiber Converts time-of-flight into distance based on speed of light in glass Plots returned signal level vs. distance OTDR can measure the loss of fiber sections, as well as the loss and
reflectance of connections, splices, splitters, macrobends or breaks.
OTDR Provides Loss vs. Distance
PIN
POUT
C1
S1
C3
Fiber
C2
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● OTDR setup offers: Multiple Distance (Range) settings Multiple Pulsewidth settings Variable Averaging Times Variable filter / resolution settings
● What settings should you choose? OTDRs offer automatic settings, but also provide experienced users
with manual control of pulsewidth, averaging time and filter settings Pulsewidth selection requires tradeoff between dynamic range and
event resolution Longer averaging times improve dynamic range, but tests take longer
OTDR Settings
Setting Range
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Too short: less than link length
Link
Can’t see entire link –unpredictable results
Good: about 1.2x to 2x link length
Link
Good trace – can see end of fiber.
Too long: much larger than link length
Link
Trace is “squashed” into left side of display.
Selecting Pulsewidth
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Too narrow:
Trace “disappears” into noise floor.
Link
About right:
Events can be seen and trace is smooth.
Link
Too wide:
Can’t resolve events
Link
Where is this this event?
OTDR Time & Distance
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10 ns 1 m30 ns 3 m
100 ns 10 m1000 ns = 1 µs 100 m3000 ns = 3 µs 300 m
10,000 ns = 10 µs 1,000 m
Useful OTDR rule of thumb: Distance (m) = Time (ns) / 10
Examples:
10m Jumper
PW=30 ns= 3 m
With 30 ns PW:Able to resolve 2 connectors 10m apart
10m Jumper
PW=100 ns= 10 m
With 100 ns PW:Unable to resolve 2 connectors 10m apart
Setting Test Time (Number of Averages)
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About right:
Trace is smooth.
Link
Too few:
Trace is noisy – noise floor is too high.
Link
Too many
Trace is smooth but excessive test time.
Link
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● If OTDR test attempted from the OLT end: Normal trace up to the splitter Backscatter &reflections from drop fibers overlap beyond the splitter
– Unacceptable loss in one drop fiber may be hidden by backscatter or reflections from overlapping drop fibers
If only a few drop fibers attached to a high split ratio splitter, splitter will appear as a high-loss event– May be declared as the end of the fiber
What’s Unique When Tracing a PON?
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● Use OTDR to Trace Fiber from ONT towards OLT Detect connectors, splitters, and optical faults Display “trace” showing fiber loss and reflections Measure loss at connectors, splitters, faults and macrobends Typically test at 1310 & 1550 (upstream & downstream λ) 1550 & 1625 nm show bending losses not seen at 1310 nm
Construction Phase OTDR Test
Video Serving Office (VSO)
OLTCWDM
FDF
1490 nm1310 nm
1550 nm
Video Overlay
(Optional)
FeederFiber
DistributionFiber
DropFiber
ONT
CustomerPremises
Outside Plant
Splitter
TraceNetwork
FLX380
FLX380
FDH
FLX380
OTDR Trace Display
Distance
Loss
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Use OTDR to “Trace” Fiber
OLTFeederFiber
DistributionFiber
DropFiber
CWDM
FDF
1490 nm1310 nm
1550 nm
ONT
CATV Video Optional
FeederSplitterDistributionDrop
Splitter Loss
ConnectorLoss
End-to-EndLoss
Video Serving Office (VSO)Customer
Premises
Outside Plant
TraceNetwork
FLX380
Reflectionsat Connectors
FDHSplitter
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● Measure network power levels: OK (power levels are acceptable) Dim (one or more power levels are low) Dark (no light due to break or severe bend)
● Must not test a live PON fiber using a “normal” OTDR Test at 1310, 1490, or 1550 will disrupt service to other customers! Downstream signals at 1490 or 1550 nm interfere with a normal
OTDR’s receiver
● In-service OTDR test can be performed with a PON-optimized live-fiber OTDR which includes: An OTDR laser at an out-of-band wavelength (e.g. 1625 nm) A filtered detector to reject in-service wavelengths (e.g. 1490, 1550)
FTTx PON – In Service Fault Location
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● Measure optical power: At output of OLT or Video Output at Video Serving Office At input or output of Splitter at Fiber Distribution Hub At input to ONT at Customer Premise
Measuring Optical Power in FTTH
Video Serving Office (VSO)
Outside Plant CustomerPremises
OLT
FDH
Feeder
Distribution
DropCWDM
FDF
Feeder Splitter Distribution Drop
20 km reach typical
1490 nm1310 nm
1550 nm ONT CATV Video
MeasurePower
MeasurePower
MeasurePower
OPM4
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Fault-locating a live (in-service) customer fiber
FTTx PON – In Service Fault Location
Feeder Fiber
Customer Fiber
conn
ecto
rized
spl
itter
Drop Cable
TP5
SplitterCabinet
LaunchCord
1490 nm(1550 nm)
OLT
To other customers
1625 nm
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1. Measure downstream power level at ONT2. If the customer fiber is ‘dark’
Use normal or PON OTDR to locate the break or severe bend Test at 1550 or 1625 nm to detect bending losses
3. If the customer fiber is ‘dim’ Use a live fiber OTDR to locate the break, macrobend, or poor
connection/splice Use high resolution (short pulse width) settings to detect faults in
the short customer drop fiber User wider pulsewidths to detect faults between cascaded splitters
(higher dynamic range)
4. If power levels at customer fiber are acceptable You don’t need to use an OTDR The problem is probably not in the PON (is not fiber related) Replacing the ONT module is often first & only required step
FTTx PON – In Service Fault Location
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FTTx PON – In Service Fault Location
Receive Cord
Launch Cord
FeederFiber
TP5
TP1
Distance
RelativePower (dB)
SplitterLoss
(not to scale)
End-to-endPON Loss
Customer fiber &drop cable
Splitter (connection)
If the OTDR is set up to test through the splitter, it may not be able to locate faults on the customer fiber…
Distance
RelativePower (dB)
(not to scale)Launch
CordCustomer fiber &
drop cable
Macrobend
So fault location of a live (in service) customer fiber should be performed using a high resolution (short pulsewidth) set-up.
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● In large headends, it may be difficult to locate both ends of one fiber On shorter fibers, inject visible light using VFI and look for glow at far end On longer fibers, inject fiber identifying test tone at one end using an OLS On singlemode fibers, use OFI to detect tone without disrupting live service On unused fibers, connect OPM to far-end fibers to detect fiber carrying tone
Using Tone to Identify Specific Fibers
Inject Fiber Identifying Test Tone
Inject Visible Light
Indicate Live Traffic
or Tone Detected
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● When applied to a splitter pigtail at FDH, an Active ONT Identifier detects upstream (1310 nm) GPON or EPON signals from an ONT while ignoring downstream (1490 and 1550 nm) signals
● Similar to an Optical Fiber Identifier (OFI), but … Does not detect normal traffic Works only on drop fibers in FTTx PONs Can be used with either SMF-28e or BIF
● Verify drop fiber is out of service before disconnecting for troubleshooting or reassignment Fewer ‘technician’ alarms
● Identify and re-use splitter ports (and drop fibers) whichare connected at the FDH but not assigned to a customer Re-use existing FTTx infrastructure Reduce capital and construction expenses
Active ONT Identification
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Active ONT Detection
OLT
ONT ONT ONT ONT ONT ONT
Splitter
FDH
“Parking” ports
F2 fiber ports
F1 fiber
F2 fibers
ONT detected !Flash Flash
ONTActive
Not Detected
OFI-FTTx
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Inactive or Missing ONT Detection
ONT ONT ONT ONT ONT ONT
“Parking” ports
Splitter
F2 fiber ports
FDHOLTF1 fiber
X
F2 fibers
ONT not detected
On
ONTActive
Not Detected
OFI-FTTx
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● Dirty or damaged fiber end-faces are a primary cause of poor optical network performance
● FOCIS Flex enables visual inspection of magnified end-faces Auto-focuses, captures, and applies IEC Pass/Fail analysis
● Cleaning supplies quickly and easily remove end-face contamination
Inspection & Cleaning
