In all countries, multi-pair copper cable networks are being replaced by fiber optic cables, since a cable with 8 optical fibers, considerably smaller than those commonly used, can support the same communications as 60 copper cables with 1800 pairs or 4 coaxial cables with 8 tubes, all with a much greater distance between repeaters.
In addition to the bandwidth available in fiber optics, this medium offers several advantages over conventional telephone networks, such as immunity to noise and interference, signal multiplexing, absence of electrical signals, reduced weight and dimensions, and compatibility with digital technology.
Installing this type of network requires specific equipment to work with the various elements available in the network.
For joining different fiber optic cables, we can use two solutions depending on the needs and requirements:
Fusion Splicing System:
The Corning OptiSplice family of fusion splicers offers fiber splicing capabilities using three different fusion systems: LID (Light Injection and Detection), CDS (Core Detection), and L-Pas (Fiber Profile Alignment).
The fusion process involves joining fibers using an electric arc that melts the glass fiber, merging the different fiber densities within the cable and achieving attenuation levels below 0.05 dB in all cases.
LID System : This system enables fusion through power measurements. Single-mode light (1300nm) is injected into the core of one fiber by means of the bender on the left (emitter) and received by the other fiber at the bender on the right (receiver). By controlling the light reception level during fusion, we achieve the optimal transmission point for each fusion performed.
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CDS System : This system allows for rapid fiber pre-alignment.
A small electric arc illuminates the fibers, enabling the fusion splicer to take a digital photograph, detecting and analyzing the core of both fibers. The fusion is performed by aligning and joining these cores, eliminating any eccentricities in the cables.
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L-PAS System : This system analyzes fiber profiles (fiber beginning/end,
core beginning/end) and uses the correlation method to calculate the exact positioning of the fibers, control pre-alignment with great accuracy, and detect any shadows or defects along the entire exposed fiber.
Camsplice Mechanical Splicing System.
The Camsplice is a fast and easy-to-use mechanical splicing system for single-mode and multimode fibers. Its main feature is the eccentric lock (Cam) that secures the inserted fibers without the need for adhesive. Together with a high-precision V-shaped glass groove, this mechanism forms a patented positioning method that ensures very accurate fiber placement.
With this system, we achieve splice attenuations on the order of 0.05 dB.
Once the fiber optic cable is installed, it is necessary to terminate the fibers in elements that facilitate their subsequent connection.
Depending on the fiber termination location (distribution cabinet, wall box, optical equipment, PTRO, etc.), we can use various applications:
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Pigtail Termination:
A pigtail is a fiber optic cable with a factory-assembled connector at one end, which will be connected to the corresponding distribution system. The unconnected end will be joined to the termination of the incoming fiber optic cable.
Both cables must be prepared, exposing 125 µm of fiber to perform the fusion splice between them. The splice must then be protected (using heat-shrink tubing or crimping tape) and placed in its corresponding splice tray.
This system provides a line termination with low attenuation and allows for easy distribution and patching of fibers depending on the application.
The market offers a wide variety of hardware for performing these terminations (wall boxes, distribution cabinets, subracks, etc.), achieving high transmission and distribution capacity
in confined spaces.
Mechanical Connectorization.
As with fiber splicing, Corning offers mechanical connectorization for final connectorization using pre-polished connectors. This is made possible by the patented Unicam® system.
The connector has a fiber end inserted into the ferrule, with final polishing performed at the factory. The Unicam connector contains an internal mechanical splice that aligns and matches the incoming fiber with the pre-polished fiber end inside the connector.
The assembly is extremely quick and easy and allows us to terminate the fiber in various standard connectors at a very low price.
Fiber optic connectors:
Controlling the connector surface is key to ensuring network reliability. The bend radius, apex offset, and fiber undercut are three other critical parameters that affect connector performance in the medium and long term, so these parameters are closely monitored during the assembly process.
Once the cables are installed, two parameters become vitally important:
Insertion loss: Power loss resulting from inserting the connector into the network.
Return loss: Signal level returning to the source due to reflections.
The choice of connector polish type (PC, APC, SPC, UPC) also greatly influences both return and insertion loss.
Common uses for patch cords include interconnecting the outside plant fiber optic cable with optoelectronic equipment and/or cross-connecting fiber optic cable segments.
Measurement Equipment
After installing, modifying, or repairing a fiber optic system, measurements and tests are extremely important to ensure consistent and satisfactory operation
network performance. The measurement results indicate the network quality in numerical terms, reveal system errors, and clarify the causes of failures, especially when products from different suppliers have been used.
The main measurement parameters of a fiber optic network are:
- Network attenuation.
- Absolute system level.
- Receiver sensitivity.
- Total system bandwidth.
OV1000 OTDR
is used to graphically display the fiber's condition and measure signal loss. Its main advantage is that it allows for the localization of issues along the fiber, such as splices, connections, potential installation faults, or defective materials.
These devices operate on the principle of optical scattering return measurement. They send a light pulse along the fiber and measure the backscatter, or reflected light.
is the most versatile instrument among fiber optic measurement equipment.
It is a compact and modular optical reflectometer designed for testing, documentation, and measurements in local area network (LAN), carrier, CATV, and FTTx fiber optic networks.
It is available in various wavelength combinations (850, 1300, 1310, 1490, 1550, and 1625 nm) and dynamic ranges.
This OTDR model is easy to use and extremely precise, with an attenuation resolution of 0.001 dB, 128,000 measurement points for high resolution, three testing modes (automatic, advanced, and templates), internal memory for 1,500 traces, 8-hour battery life, lightweight design, 10/100 Mb/s Ethernet Cat. 5 RJ45, touchscreen, and user-friendly software for creating professional reports, including bidirectional analysis and a fast printing function.
Its advanced design allows us to reduce the measurement dead zone to a distance of between 1 and 4.5 meters.
Light Sources and Power Meters: OTS and LTX Series.
A light source and a power meter are essential components of any technician's equipment.
These devices allow us to measure the total loss of a transmission line.
The light source acts as a transmitter at one end of the fiber optic cable, emitting at a specific power level. The power meter is located at the other end of the line, collecting the light emitted by the transmitter. Through mathematical calculations, it measures and displays the total line losses.
The Corning product range offers several versions of this equipment. We can have the light source and power meter in two separate units, transmitting and receiving at different points in the network, or we can obtain a power meter with an integrated light source in a single unit, allowing us to transmit and receive from the same location with the same device.
This family of equipment simplifies the work, as it features automatic wavelength detection, eliminating potential errors due to incorrect transmitter and receiver alignment.
The equipment can be purchased with two, three, and four wavelengths.
Active Fiber Identifier.
The active fiber identifier is an easy-to-use auxiliary tool for the installation and maintenance of fiber optic systems. It safely detects fiber optic signals and indicates their transmission direction without interrupting network operation. The signal direction and type (continuous, pulsed, or none) are displayed via indicator lights. An integrated power meter is also available, which simultaneously measures and displays the relative power of the fibers.
It operates using non-intrusive detection technology, ensuring no damage to the network during or after testing.
Thanks to the wide range of options offered in both materials and instrumentation, Rextel Private Networks provides a specialized engineering team to analyze the needs of each client and/or installation, integrating solutions tailored to the specific requirements of each case. Selecting the right materials and having the appropriate equipment is the only way to implement a communications network with the quality demanded by today's market.
Article prepared by the Rextel Technical Department
