Features of Fiber Optic Cable
Apr 27, 2024
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1. When a structured cabling system requires long-distance transmission between buildings, where in-building cabling combines telephones, computers, hubs, dedicated switches, and other information systems into high-speed networks, or when it is laid alongside external networks, particularly power cable networks with requirements to resist electromagnetic interference, it is advisable to use fiber optic digital multiplexing equipment as the transmission medium. The fiber optic transmission system should meet comprehensive transmission requirements for telephones, data, computers, television, etc., within and between building complexes. For computer local area networks, multimode fiber optic cables are recommended; for public telephone or data networks, single-mode Optical fibers should be used.
Fiber optic transmission systems can provide higher speeds and transfer greater volumes of information, making them suitable for large-scale structured cabling systems. Practical fiber optic transmission devices, components, and cables are currently available.
A structured cabling system integrates various information systems such as voice, data, video conferencing, surveillance television, etc. Using fiber optics can extend transmission distances, hence structured cabling is an integrated distribution network system composed of both fiber and copper patch cables. Fiber optic systems form networks resistant to electromagnetic interference.
Generally, multimode fiber optic cables are suitable for short-distance computer local area networks. For long-distance transmission in public telephone networks or data networks, single-mode fiber optic cables are used for convenience in connectivity. It is preferable for the structured cabling to adopt compatible specifications with these networks.
2. When the structured cabling system employs optical fiber components for cross-connect hardware, it may serve as the main cross-connect location for fiber optic cables. Backbone fiber cables extend from this central termination and ingress/egress point to other floors, distributing fiber cables horizontally along each floor through cable and connections.
3. The fiber optic transmission system should utilize standard single-unit fiber optic connectors. Connectors can terminate at fiber optic cross-connect units, with connections using ceramic ferrules not exceeding 0.4dB of attenuation per connection point. For plastic ferrule connectors, the attenuation should not exceed 0.5dB per connection point.
For ceramic ferrule STⅡ connectors, the attenuation change after 1,000 re-connections should be less than 0.2dB. For plastic ferrule STⅡ connectors, the attenuation change after 200 re-connections should be less than 0.2dB.
Regardless of the type of STⅡ connector, the average time needed to install one connector is about 16 minutes. However, installing 12 STⅡ connectors at the same time reduces the average installation time to 6 minutes per connector.
4. Structured cabling systems should use enhanced multimode fiber optic cables with a fiber diameter of 62.5mm and a cladding diameter of 125mm, with nominal wavelengths of 850nm or 1300nm; single-mode fiber optic cables with nominal wavelengths of 1310nm or 1550nm can also be used.
For in-building structured cabling, multimode fiber optic cables are typically used, while single-mode fiber optic cables are generally used for long-distance transmission.
5. The bit rate and digital interface characteristics of the fiber optic digital transmission system should comply with the following specifications:
□ PDH digital serial bit rates should meet the national standard "Pulse Code Modulation Communication System Series" (GB 4110-83) as shown in the table below.
Table of Serial Bit Rates
|
Digital Hierarchy Level
|
Primary Group
|
Secondary Group
|
Tertiary Group
|
Quaternary Group
|
|---|---|---|---|---|
|
Nominal Bit Rate (kbps)
|
2048
|
8448
|
34368
|
139264
|
□ Bit rate deviations, pulse waveform characteristics, code types, and input and output specifications for digital interfaces must comply with the national standard "Digital Interface Parameters for Pulse Code Modulation Communication System Networks (XGB7611-87)".
6. Fiber optic transmission systems should use loose tube or central core type fiber optic cable bundles but may also use ribbon fiber optic cables.
7. Standard fiber optic cable connection devices in the transmission system, apart from supporting connectors, should also directly support cable bundles and jumper cables.
8. Connections for all types of fiber optic cables should use universal cable boxes, providing reliable connections and protective casings for joint sections of cable bundles, ribbon cables, or jumper cables. The cable entries provided by the universal cable box should be capable of accommodating multiple building cables simultaneously.
Like copper cables, fiber optic cables are also available in armored, ordinary, and filled types.
When connecting ribbon cables to one another, array connectors must be used. To interconnect a ribbon cable with a non-ribbon indoor cable, an enhanced conversion connector should be utilized.
9. Fiber optic cabling networks can be installed in buildings or complexes and can support a variety of broadband communication services not explicitly planned in the initial design stage. Such cabling systems can be used as independent local area networks (LANs) or for local image transmission of video conferencing, surveillance television, connecting to the public telephone network.
