Introduction
To ensure you get accurate measurements each time you use your OTDR for testing fibre optic cabling, there are a number of things you should be doing every time.
In this blog we will look at those points, which if followed will mean you can quickly and effectively get the correct measurements every time. Saving yourself considerable time and hassle.
Use Appropriate Settings
When using an OTDR, it's important to use appropriate settings for the fibre being measured. This includes setting the pulse width, distance range and threshold correctly. Using inappropriate settings can result in inaccurate measurements.
Pulse Width
The pulse width setting on the OTDR determines the duration of the laser pulse that is launched into the fibre. The pulse width affects the spatial resolution of the measurement, with shorter pulse widths providing better resolution. However, shorter pulse widths also have lower energy, which can result in lower signal to noise ratios and reduced measurement range. It's important to choose the appropriate pulse width for the specific measurement being taken.
Averaging Time
The averaging time determines the length of time that the OTDR will average the reflected light signal. Longer averaging times can improve the signal-to-noise ratio but can also increase measurement time. Shorter averaging times can reduce the measurement time but may result in a noisier measurement. It is important to choose the appropriate averaging time for the specific measurement being taken.
Distance Range
The distance range setting on the OTDR determines the maximum distance that the OTDR will measure. It's important to choose an appropriate distance range for the specific measurement being taken to ensure accurate and reliable results.
Threshold
The threshold setting on the OTDR determines the minimum signal level required for the OTDR to detect a reflection. It's important to choose an appropriate threshold level to ensure that the OTDR is sensitive enough to detect the reflections of interest.
By using appropriate settings for each measurement, the OTDR can provide accurate and reliable results.
Follow Best Practices for Handling Fibre
Fibre optic cables are delicate, and even small amounts of damage can affect OTDR readings. It is essential to follow best practices for handling and storing fibre cables, such as using proper cable management techniques and avoiding excessive bending or tension.
Avoiding Contamination
Contamination on the fibre can impact the signal quality and introduce errors in the measurement. Best practices for handling fibre include cleaning the fibre and connectors before testing and avoiding touching the fibre with bare hands.
Properly Identifying Fibre
It's important to properly identify the fibre being tested and to confirm that the correct fibre is being measured. Proper labelling and documentation can help ensure that the right fibre is being tested and that the test results are accurate and reliable.
Avoiding Fibre Stress
Any stress or damage to the fibre can impact the signal quality and introduce errors in the measurement. Best practices for handling fibre include avoiding sharp bends or kinks, avoiding pulling or twisting the fibre, and using appropriate strain relief.
Using Proper Test Equipment
The use of proper test equipment is critical to obtaining accurate OTDR test results. This includes using the appropriate launch and receive cables, ensuring that the equipment is calibrated, and using appropriate test settings.
Regular Cleaning and Inspection
Regular cleaning and inspection of the fibre, connectors, and splices can help ensure that the fibre is in good condition and that the signal quality is not impacted by contamination, damage, or wear and tear.
By following best practices for handling fibre, including cleaning and inspection, avoiding contamination, properly identifying the fibre, avoiding fibre stress, and using proper test equipment, you can help ensure that you get accurate OTDR test results.
Keep Equipment Clean and Calibrated
Dirty or poorly calibrated equipment can also affect OTDR readings. It's essential to keep your OTDR and other equipment clean and well maintained, and to calibrate equipment regularly to ensure accurate measurements.
Contamination
Dust, dirt, and other contaminants on the connectors, fibre, and test equipment can impact the signal quality and introduce errors in the measurement. Regular cleaning of equipment and connectors helps ensure that the measurements are accurate and reliable.
Calibration
Proper calibration of the test equipment is critical to obtaining accurate OTDR measurements. Calibration ensures that the test equipment is functioning properly and accurately, providing consistent and reliable results.
Signal-to-Noise Ratio
Keeping equipment clean and calibrated helps ensure that the signal-to-noise ratio is optimal for accurate measurement. A poor signal-to-noise ratio can result in measurements that are noisy or inaccurate.
Consistency
Regular calibration and cleaning help ensure that measurements are consistent over time. This helps in identifying any changes or anomalies in the fibre network and can help in diagnosing issues and planning for future upgrades or maintenance.
Increased Efficiency
Accurate measurements that are consistent over time can increase efficiency in identifying and addressing issues in the fibre network. This can help reduce downtime and prevent unnecessary costs associated with troubleshooting and repairing problems in the network.
Take Multiple Measurements
Taking multiple OTDR measurements from different locations along the fibre can help to verify the accuracy of readings and to identify potential errors or issues.
Signal Averaging
By taking multiple measurements and averaging the results, you can reduce the impact of noise and variations in the measurement. Signal averaging can help provide a more accurate representation of the true signal and can improve the accuracy and precision of the measurement.
Dead Zones
Taking multiple measurements can help reduce the impact of dead zones in the fibre network. Dead zones are areas where the OTDR is unable to accurately measure the fibre due to the signal being too weak or too strong. By taking multiple measurements, you can ensure that you capture the full length of the fibre and identify any changes or anomalies in the network.
Fibre Variability
Fibre can have natural variations that impact the signal quality and measurement accuracy. Taking multiple measurements can help identify any variations and provide a more accurate representation of the true signal.
Fibre Length
By taking multiple measurements at different points along the fibre, you can ensure that the measurement is consistent over the full length of the fibre. This can help identify any changes or issues in the network, such as breaks or bends in the fibre.
Increased Confidence
Taking multiple measurements and averaging the results can increase confidence in the measurement and reduce the likelihood of errors or inaccuracies. This can help ensure that the measurement is reliable and can be used for troubleshooting, maintenance, and planning for future upgrades or expansions.
By taking multiple measurements, you can improve the accuracy and reliability of your OTDR readings. Signal averaging, reducing the impact of dead zones, accounting for fibre variability, ensuring consistency over the full length of the fibre, and increasing confidence in the measurement are all benefits of taking multiple measurements. Overall, taking multiple measurements can help you make more informed decisions about your fibre network, improve efficiency, and reduce unnecessary costs and downtime.
Interpret Results Correctly
Interpreting OTDR traces can be challenging, especially for complex fibre networks.
Understanding the Results
The first step in interpreting results is to understand the data that is presented. This includes understanding the signal strength, loss, and reflections that are shown in the OTDR trace. By interpreting the results correctly, you can identify any issues or anomalies in the fibre network and take appropriate actions to address them.
Identifying Issues
Interpreting the results correctly can help identify issues in the fibre network, such as breaks, bends, and other types of damage. This can help in troubleshooting and planning for maintenance and repairs, reducing downtime and costs associated with network outages.
Avoiding False Positives
Incorrectly interpreting results can lead to false positives, where issues are identified that do not actually exist. This can result in unnecessary maintenance or repairs, increasing costs and reducing network efficiency.
Planning for Future Upgrades
Interpreting the results correctly can also help in planning for future upgrades or expansions of the fibre network. By understanding the current state of the network and identifying any limitations or issues, you can make informed decisions about future upgrades or expansions.
Collaboration
Interpreting results correctly can help facilitate collaboration between different teams or departments involved in maintaining the fibre network. By sharing accurate and reliable data, teams can work together more efficiently to identify and address issues and improve the overall performance of the network.
Overall, interpreting results correctly is a critical step in obtaining accurate OTDR readings. It helps identify issues, avoid false positives, plan for future upgrades, and facilitate collaboration between teams.
Conclusion
There are many things you need to do to ensure that you get accurate measurements from your OTDR every time. Taking the time to follow them will save you time and money in the long run and make your more efficient at your job.
If you want to take a closer look at our range of OTDRs click here. If you want to contact or find out more about this blog posts author, Ian Bankhurst click here.
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