Manual test using an EXFO optical time domain reflectometer

Manual testing with an EXFO OTDR involves setting up the device, selecting appropriate test parameters, acquiring fiber traces, and analyzing results to locate faults and measure fiber characteristics.

Setting Up the OTDR

1. Power on the device and ensure the battery is charged or connected to a power source.
2. Select the appropriate wavelength for testing, typically 1310 nm and 1550 nm for singlemode fibers, depending on the fiber type and network requirements .
3. Connect the fiber under test using APC connectors for singlemode ports to minimize reflectance and improve measurement accuracy .
4. Clean all connectors to prevent contamination, which can affect OTDR readings.

Configuring Test Parameters

• Manual Mode: Choose manual or advanced mode to control pulse width, averaging time, and range settings .
• Pulse Width: Select a shorter pulse for high-resolution measurements near the source and longer pulses for longer fiber spans.
• Acquisition Settings: Adjust averaging time to reduce noise and improve trace clarity. Longer averaging improves accuracy but increases test time.
• Event Thresholds: Set thresholds for detecting splices, connectors, and faults.

Acquiring OTDR Traces

1. Launch the test by sending light pulses into the fiber. The OTDR will record backscattered light to generate a trace .
2. Observe the trace for events such as splices, connectors, bends, or breaks. Each event appears as a change in the backscatter level.
3. Repeat measurements if necessary to ensure consistency, especially for long fibers or complex networks.

Analyzing Results

• Event Table: Review the automatically generated event table for distances, loss, and reflectance values .
• Bidirectional Testing: For higher accuracy, perform bidirectional measurements and average the results to account for splice loss variations .
• Compare to Reference: If available, compare the acquired trace to a reference trace to detect deviations or degradation.

Post-Processing and Reporting

• Use EXFO software such as FastReporter to generate detailed reports, including fiber length, attenuation, splice and connector losses, and total return loss .
• Reports can be customized for project documentation or quality assurance purposes.

Best Practices

• Always clean and inspect connectors before testing.
• Use APC connectors for singlemode fibers to reduce dead zones.
• Ensure the OTDR firmware is up-to-date to access the latest features and improvements .
• For complex networks, consider using iOLM software to simplify trace interpretation and reduce manual analysis errors . By following these steps, a technician can manually test optical fibers using an EXFO OTDR, accurately locate faults, and characterize fiber performance for maintenance or installation verification.