Fiber optic cable testing is a crucial process to ensure the integrity, reliability, and performance of fiber optic networks. Here's a detailed explanation of how fiber optic cables are tested:
Materials Needed
Test tool suite: This typically includes a light source and an optical power meter for insertion loss testing.
Patch panels: Used to connect two cables together without soldering.
Jumper cables: Required to complete the test setup.
Optical meter: Used to read the signal at the other end.
Protective eyewear: Specifically designed for fiber optic testing to protect the eyes from high-power optical signals.
Testing Steps
1. Set Up the Test Equipment
Purchase a test kit with a light source and an optical power meter.
Ensure that the wavelength settings of both measuring instruments are set to the same value, depending on the cable type.
Allow the light source and optical power meter to warm up for about 5 minutes.
2. Perform the Insertion Loss Test
Connect one end of the first jumper cable to the port on top of the light source and the other end to the optical meter.
Press the "Test" or "Signal" button to send a signal from the light source to the optical meter.
Check the readings on both screens to ensure they match, indicated in decibels milliwatts (dBm) and/or decibels (dB).
If the readings don't match, replace the jumper cable and test again.
3. Test with Patch Panels
Connect the jumper cables to the ports on the patch panels.
Insert one end of the cable under test into the port on the opposite side of the jumper cable connected to the light source.
Insert the other end of the cable under test into the port on the opposite side of the jumper cable connected to the optical meter.
4. Send the Signal and Analyze the Results
Check the connections to ensure they are properly set up through the patch ports.
Press the "Test" or "Signal" button to perform the insertion loss test.
The meter's reading should appear after 1-2 seconds.
Assess the accuracy of the cable connection by reading the database results.
Generally, a dB loss between 0.3 and 10 dB is acceptable.
Additional Considerations
Cleanliness: Use fiber optic cleaning solution to clean each port of the cable if you cannot see the correct power input on the screen.
Directional Testing: If you see a high dB loss, try flipping the cable under test and testing in the other direction to identify poor connections.
Power Levels: Assess the cable's dBm to determine its strength, with 0 to -15 dBm typically acceptable for cable power.
Advanced Testing Methods
For more comprehensive testing, technicians may use tools like an Optical Time Domain Reflectometer (OTDR), which can measure the loss, reflections, and other characteristics over the entire length of the fiber optic cable.
Importance of Standards
Adherence to national and international standards is necessary to maintain consistency, interoperability, and performance in fiber optic testing.
In summary, fiber optic cable testing involves setting up specialized equipment, performing insertion loss tests, analyzing results, and ensuring adherence to standards. This process ensures the reliability and performance of fiber optic networks.