Modern communication systems rely on fiber optic cables to quickly, safely, and reliably transmit data over great distances. However, even the most reliable network can break down. Knowing how to test fiber optic cable is important for finding problems that can degrade connectivity and network performance.
How To Test Fiber Optic Cable for Optimal Performance
Correct procedures for testing fiber optic cable are crucial for troubleshooting connectivity issues, performing routine network maintenance, or installing new lines. Learn about common testing methods for fiber optics, what tools are used, and the best practices to ensure success.
Common Testing Methods for Fiber Optic Cable
Several testing methods are available for different diagnostic purposes. Once you understand them, you can choose the best fit for your application.
Continuity Testing
Continuity testing verifies that the fiber optics have a continuous end-to-end connection. Connectors, breaks, and jacketing damage can all cause problems with continuity. Left unchecked, it will degrade signal quality and network performance will suffer.
To perform continuity testing on a fiber optic cable, a technician shines a light source into the end of a fiber cable while checking for signal reception at the other end. It is ideal for quick system checks or to identify faults in short cable runs.
Loopback Testing
Loopback testing is often used for continuity testing to ensure that transceivers are working correctly. You perform it by hooking a loopback module to the transceiver. It sends and receives signals, recording the values to check for signal loss.
Insertion Loss Testing
Insertion loss is the amount of signal lost during transmission over fiber networks. Measuring it can help identify issues in cables, transceivers, connections, and splices.
To perform insertion loss testing, you must connect a power meter to one end of the cable. Then, you shine an optical light into the other cable end. The meter provides a measurement that you then compare to the input to calculate losses.
Insertion loss testing of fiber optic cable provides a dB value for the amount of signal lost between the light source and the other end. It is commonly used to verify that a fiber optic cable meets specifications.
Optical Return Loss Testing
ORL testing shines light into an optical fiber and measures the amount of light reflected back. High return loss degrades high-speed network performance by interfering with laser transmitters. You use an ORL meter or optical time-domain reflectometer to perform ORL testing.
OTDR Testing
OTDR is a comprehensive test of fiber optic cable that can accurately pinpoint trouble spots in the network. It evaluates cable condition and locates faults, connector losses, and splices.
OTDR testing uses an Optical Time Domain Reflectometer to send light pulses into the optical fibers. It then measures and analyzes reflection to trace the network. OTDR produces an accurate visualization of the fiber’s condition, including total length and event losses.
Originally developed for diagnostics on long fiber runs, newer technology makes OTDR tests of fiber optic cable a valuable tool for shorter cables. This is especially true when it is difficult to physically access the entire cable length.
Tools Used To Test Fiber Optic Cable
Having the right tools makes testing easier and more accurate. Some of the most common tools for running tests on fiber optic cable include:
- Fiber Optic Inspection Scope: A digital or optical scope used to inspect connectors for contamination, proper polishing, and material defects
- Fiber Optic Power Meter: Used to measure optical power transmitted through a fiber optic cable.
- Optical Light Source: Often used with an OPM, this produces a light source to test for continuity and signal loss
- Optical Time Domain Reflectometer: An advanced tool that sends light into a fiber cable, records reflections, and analyzes them to create a graphic representation of the network
- Visual Fault Locator: A handheld tool that uses red light to visually identify breaks in fiber cable, faulty connections, and bad splices
Always ensure your tools are properly maintained, stored, and cleaned before using them. All equipment should be calibrated before you test fiber optic cables. Using reference cables with a known value, you can zero out meters before testing to help establish a proper reference for accurate readings.
Best Practices for Testing Fiber Optic Cable
Following industry standards and best practices for testing fiber optic cable will help you achieve accurate results. These apply to test procedures, equipment, and processes used.
Clean Connections
Even minor contamination can interfere with test results, so you must clean every connection before testing. Use lint-free wipes, isopropyl alcohol, or a cleaning cassette to remove any dust. Then, carefully inspect the connections to ensure they are clean and free from damage.
Follow Proper Handling Procedures
Optical fibers are flexible, but they have limits. Never exceed the minimum bend radius when testing fiber optic cable. It can cause permanent damage to the glass strands and degrade signal quality. Following proper cable handling, management, and labeling procedures during testing helps ensure the structural integrity of your network components.
Record Procedures and Results
Accurate documentation provides a record of your tests to create a picture of system performance and health. It also serves as an excellent reference point for comparison. For example, if you are experiencing performance issues, you can test the system and compare the results to those from earlier tests.
Data that you should record includes:
- Cable lengths, types, colors, etc.
- Connector types and locations
- OTDR traces
- Test results
Having this record does more than facilitate troubleshooting. It can also help you file for warranty coverage and plan network upgrades as needed.
Use the Correct Wavelength
Fiber networks can carry various wavelengths. You should perform testing using the wavelength of your network and equipment to provide the most relevant results for your system.
Trust Equal Optics To Know How To Test Fiber Optic Cable
Equal Optics is a leading supplier of tier-one network components. We understand the value of testing fiber optic cable and its components. Contact us to ensure your fiber optic cables are tested for peak performance.
