Fiber Optic Installation: Techniques and Troubleshooting
Item 16: Outdoor Fiber Installation
1. Outdoor Fiber Piping
Buried pipes are commonly used for outdoor fiber installations. These pipes house multi-fiber cables, often with 16 fibers structured in 8 groups of 2. Each cover protects two fiber cables.
2. Laying Optical Fiber Outdoors
Fiber cables are introduced through underground conduits. Due to their weight, they are laid from one casket to another. The fiber comes in rolls of several kilometers. A lathe with a guide is used to introduce the fiber into the passageway, extending to intermediate and final chests.
3. Fiber Optic Torpedo
These are tight boxes protecting fiber optic joints, used for making joints or changing cable types.
4. OTDR Initials
OTDR stands for Optical Time Domain Reflectometer, useful for troubleshooting.
5. Using OTDR
OTDRs visualize fiber attenuation over distance, helping identify breaks, joint and connector attenuation, splice locations, and connectorized fiber issues.
6. OTDR Dead Zone
The initial distance in an OTDR where measurements are unreliable is called the dead zone.
7. Overcoming Dead Zone Limitation
A phantom coil of 1 km is connected to overcome the dead zone.
8. Identifying Fiber Portions in OTDR
Key events in an OTDR include:
- Home of action: A large peak from the phantom coil.
- Tender Fiber: Consistent attenuation without peaks, showing dB/km.
- Final Fiber: A zigzag line with reflection due to the connector.
9. Connectors
- Connector/Adapter: Reflection followed by power loss, indicating connector or adapter presence.
- Hoses: A peak followed by another reflection.
10. Identifying Mechanical/Fusion Joints
- Mechanical Splice: Power loss of about 0.1 dB without reflections.
- Fusion Splice: Minimal power loss, around 0.01 dB.
Item 15: Fiber Optics Cable Specifications
1. Minimum Radius of Curvature
The minimum bend radius to prevent losses in indoor installations is typically 3-6 cm, or multiples of the cable’s outer diameter.
2. Relationship with Laying Spokes
Fiber installations should avoid sections with folds, bends smaller than the minimum radius, and abrupt direction changes.
3. Fiber Drive Box
These boxes allow fiber segments to run without damage. Traction corner boxes ensure the fiber maintains the minimum radius of curvature under stress. Intermediate pull boxes assist in laying long straight stretches, reducing fiber tension.
4. Minimum Dimensions of Pull-Corner Box
The minimum size is 3R x 2R (R being the radius of curvature).
5. Intermediate Stages
Intermediate stages should be 4R wide and 2R long.
6. Fiber Pipes Size
- Diameter should be at least twice the fiber’s radius of curvature in pipes.
- Width should be at least twice the fiber’s radius of curvature in sewers.
7. Laying in Pipes
- Avoid twisting the optical fiber cable.
- Do not use clamps or fasteners that may damage the cord.
- Secure vertical cables to the wall with a mesh.
- Avoid stacking fibers; use crush-resistant coatings if necessary.
8. Fiber Junction Box
Boxes used to protect joints from external damage, often wall-mounted.
9. Fiber Distribution Panel
Panels allowing the termination of laid fiber on a connector, with a hose connecting to the receiver.