How to Check Fiber Fusion Splice Loss with OTDR Malaysia
How to Check Fiber Fusion Splice Loss with OTDR Malaysia
Fusion splicing is widely used to create permanent low-loss connections between optical fibers.
A properly completed splice should introduce relatively little optical loss.
However, poor fiber preparation, contamination, alignment problems or mechanical stress can result in higher-than-expected splice loss.
An OTDR (Optical Time Domain Reflectometer) can help technicians identify splice events, estimate their location and evaluate how they affect a fiber link.
For Malaysian fiber installers and maintenance teams, a portable OTDR such as the Noyafa NF-981 can be useful for installation checks and troubleshooting.
What Is Fusion Splice Loss?
Whenever two fibers are joined, a small amount of optical power may be lost at the connection.
This is known as:
Splice Loss
The actual acceptable loss depends on the fiber, installation requirements, equipment and project specifications.
The important point is that a splice showing unusually high loss compared with other similar splices may deserve further investigation.
What Causes High Fusion Splice Loss?
Possible causes include:
Dirty fiber
Poor cleaving
Incorrect fiber preparation
Fiber core misalignment
Contaminated electrodes or splicer components
Incorrect fusion parameters
Damaged fiber
Mechanical stress after splicing
Excessive bending near the splice
A fusion splicer's estimated loss can provide useful immediate feedback.
However, testing the completed link with appropriate external instruments provides additional information about the installed fiber path.
How Does a Fusion Splice Appear on an OTDR?
A fusion splice is generally a non-reflective event.
On a conventional OTDR trace, it often appears as a small step in the backscatter level rather than a large reflective peak.
The OTDR can estimate:
Splice location
Event loss
Distance from the tester
If a splice produces excessive loss, the event may stand out compared with other splices along the link.
Fusion Splice vs Connector on an OTDR Trace
These two events often look different.
Fusion Splice
Typically:
Non-reflective
Appears as a step in the trace
Relatively low loss when properly completed
Connector
Typically:
Reflective
May produce a noticeable peak
Can show both reflection and insertion loss
Understanding this distinction helps technicians interpret OTDR results more accurately.
Step 1: Clean the OTDR Connection
Before performing the test, make sure the relevant connectors are clean.
Dirty connectors can introduce excessive loss and reflection, affecting the trace.
Use appropriate fiber inspection and cleaning procedures before connecting the OTDR.
Step 2: Use a Launch Cable
For better OTDR testing, connect an appropriate launch cable between the OTDR and the fiber under test.
The setup becomes:
OTDR → Launch Cable → Fiber Link
The launch cable moves the first link connector away from the OTDR's initial dead zone.
This allows technicians to evaluate the first connection more effectively.
Step 3: Select the Correct Wavelength
The Noyafa NF-981 supports:
1310nm
and
1550nm
Testing at both wavelengths can provide additional information about the fiber link.
If a suspicious event behaves very differently between wavelengths, technicians can investigate whether factors such as fiber bending may also be involved.
Step 4: Select an Appropriate OTDR Range
Choose a test range that covers the expected fiber length.
For example, if the link is approximately 3 km, use a range suitable for analysing the entire cable without selecting an unnecessarily large distance.
Correct range selection can improve trace readability.
Step 5: Select the Pulse Width
Pulse width affects both measurement reach and event resolution.
A narrow pulse generally provides better ability to separate nearby events.
A wider pulse provides more energy for longer or higher-loss links but can reduce spatial resolution.
A simplified rule is:
Narrow pulse → Better event separation
Wide pulse → Better measurement reach
Choose according to the fiber length and network architecture.
Step 6: Run the OTDR Test
Start the measurement and allow the OTDR to analyse the fiber.
Look for expected splice locations.
If the installation drawing indicates a splice enclosure around 800 metres, check whether the OTDR identifies an event around that distance.
The OTDR distance can then be compared with the physical cable route.
Example: High-Loss Splice
Imagine a 2 km fiber link contains three fusion splices.
The OTDR detects events around:
420 m
960 m
1,480 m
The first and third splice events appear relatively small.
The event at 960 m shows noticeably greater loss.
The technician checks the splice record and confirms that a splice enclosure exists around that optical distance.
The enclosure can then be opened and the relevant splice inspected.
If necessary, the fiber can be re-cleaved and re-spliced before repeating the OTDR test.
Why OTDR Distance Is Useful
Without OTDR information, technicians may know that the total link loss is excessive but not know which splice is responsible.
If a long fiber route contains many splice closures, inspecting every enclosure can take considerable time.
An OTDR helps identify which location deserves attention first.
Test from Both Directions
For more accurate splice evaluation, technicians may test a fiber from both directions when appropriate.
Why?
OTDR splice-loss measurements can be influenced by differences in backscatter characteristics between the two fiber sections.
A splice may even appear to show an unusual result or apparent "gainer" from one direction.
Testing from both ends and appropriately analysing the bidirectional results can provide a more representative assessment of splice loss.
This is especially important when accurate splice-loss evaluation is required.
What Is an OTDR Gainer?
Sometimes an OTDR may display an event that appears to have negative loss — as if the signal became stronger after the splice.
The splice is not actually generating optical power.
This phenomenon can occur because the two fiber sections have different backscatter characteristics.
Testing from the opposite direction may show a corresponding loss.
This is one reason professional splice analysis may use bidirectional OTDR measurements.
OTDR vs Fusion Splicer's Estimated Loss
Modern fusion splicers often estimate splice loss immediately after fusion.
This estimate is useful for field quality control.
However, it is not the same measurement method as OTDR testing.
A practical workflow can be:
Fusion Splicer → Immediate splice estimate
OTDR → Evaluate the splice as part of the installed fiber link
For projects requiring formal acceptance measurements, follow the specified testing standard and procedure.
OTDR vs Optical Loss Test
An OTDR provides event-based information along the fiber.
An optical light source and power meter can measure end-to-end insertion loss.
These methods provide different information.
A complete professional test procedure may require both depending on project requirements.
Do not assume that an OTDR result automatically replaces every other optical loss measurement.
Intelligent Event Analysis
The Noyafa NF-981 includes intelligent event analysis.
This can help technicians identify significant events without relying entirely on manual trace interpretation.
The event map may make it easier to review:
Event distance
Event sequence
Loss events
Reflective events
Fiber endpoint
For newer technicians, this can simplify initial OTDR troubleshooting.
Can OTDR Detect Every Bad Splice?
OTDR is a powerful diagnostic tool, but results depend on:
OTDR settings
Dynamic range
Pulse width
Dead zone
Fiber characteristics
Splice location
Network architecture
Closely spaced events can also be difficult to separate.
Technicians should interpret OTDR results together with installation records and other optical measurements.
Where Is Fusion Splice Testing Important?
FTTH Networks
Check splice points along distribution and drop fiber.
CCTV Fiber Networks
Evaluate fiber splices on long backbone links.
Factory Networks
Identify high-loss splice events between buildings and production areas.
Campus Networks
Troubleshoot splice closures along inter-building fiber routes.
Building Fiber Backbones
Check splices between communication rooms and distribution points.
Telecommunications
Evaluate installed fiber during commissioning and maintenance.
Noyafa NF-981 for Splice Troubleshooting
The NF-981 supports:
1310nm / 1550nm OTDR
Intelligent event analysis
Optical Power Meter
Visual Fault Locator
Optical laser source
SOR file storage
RJ45 wire mapping
For contractors who perform fusion splicing as part of installation and maintenance work, OTDR capability adds an important diagnostic layer.
Instead of only knowing that total optical loss is too high, technicians can investigate:
Which event may be causing the problem?
and:
How far away is that event?
Important: OTDR Does Not Replace Good Splicing Practice
An OTDR helps identify and analyse fiber events.
It cannot compensate for poor installation.
Good fusion splicing still requires:
Proper fiber stripping
Correct cleaning
High-quality cleaving
Suitable fusion settings
Proper splice protection
Correct fiber management
Testing should verify good workmanship, not replace it.
Noyafa NF-981 OTDR Malaysia
For Malaysian fiber contractors, OTDR testing can make splice troubleshooting much more efficient.
If a fiber link contains several splice points, the ability to identify an abnormal event by distance can reduce unnecessary inspection work.
The Noyafa NF-981 provides a portable way to combine OTDR analysis with other useful fiber testing functions.
For everyday installation and maintenance, it can help technicians move from:
"The fiber has too much loss."
to the much more actionable question:
"Which location should we inspect?"
Contact MTM Precision
For Noyafa NF-981 OTDR Fiber Tester Malaysia, fusion splice testing, fiber optic troubleshooting equipment and technical enquiries, contact MTM Precision.
MTM Precision Sdn Bhd
No. 29-1 & 29-2, Jalan Bandar 18,
Pusat Bandar Puchong,
47160 Puchong, Selangor, Malaysia.
Website: www.mtmpre.com.my
WhatsApp: +6016-660 7346
Email: mtmpre@yahoo.com
24 Aug 2026
