Shulou(Shulou.com)11/24 Report--

"if there is an optical cable under it, excavation is strictly prohibited." What is the fiber optic cable for? What will happen if you dig it up?

When you are staying at home, happily surfing the Internet, watching HD IPTV and browsing moments, if the nearby fiber optic cable is dug up, these things may have to say goodbye.

Because optical cable is an important part of communication transmission, it shoulders the important mission of transmitting network signals.

What is a fiber optic cable? When it comes to optical cable, we have to mention optical fiber. The yellow cable in the following picture is optical fiber, commonly known as tail fiber. (if you want to learn more about optical fiber, see the complete book of optical fiber. )

The optical fiber from the operator's computer room should be connected to another room, or building, or even a home light cat several kilometers away, but you cannot directly pull a long optical fiber to connect it. A single optical fiber is easy to bend, damage, and poor impact resistance, just like a chopstick is easy to break, but a chopstick is difficult to break. In order to ensure the safety of optical fiber, multiple optical fibers that transmit optical signals over long distances need to be tied together and merged into optical cables. And in order to avoid the damage of external high temperature, Rain Water, rats, insects and birds, he also needs to be equipped with multi-layer armor: strengthening components, protective layers and fillers, etc.

Okay, now let's take a look at the components of the fiber optic cable:

Cable core: composed of one or more optical fibers.

Reinforcement component: a component used to enhance the tension resistance of an optical cable. The material is generally steel wire or non-metallic fiber. It is usually located in the center of the cable core and sometimes in the protective layer.

Protective layer (usually inner sheath → armor layer → outer protective layer three-layer structure): used for waterproof and moisture-proof, tensile, compression, bending and so on. The materials are polyethylene or polyvinyl chloride (PE or PVC), polyurethane polyamide, aluminum and steel and other metals. The position is one or more layers of cylindrical sheath from the inside to the outside. The armor layer is generally steel wire and steel belt, which is located in the outer protective layer, mainly to prevent external forces from damaging the optical cable.

In addition, there will be filling materials for moistureproof and waterproof between the cable core and the protective layer. The filling material is generally moistureproof ointment.

What are the common types of optical cables? Just like snowflakes, although they are basically similar in shape, there are no two snowflakes of exactly the same shape in the real world. Scientists have found snowflakes of tens of thousands of shapes, and optical cables with different structures are also beautiful snowflakes in terms of cross section, and each kind of snowflake (cross section) has a unique aesthetic feeling. According to different structural shapes, optical cables can be divided into layer stranded type, skeleton type, bundle tube type and ribbon type.

Layer stranded: a loose or tight-sheathed optical fiber stranded around a central reinforcing member. Tight-sheathed or loose-sheathed optical fiber refers to the optical fiber wearing protective coats, which are mainly made of polypropylene, nylon-12, polyester elastomers, fluorine-46, fiber reinforced plastics, oriented stretching polymers and so on. Layer stranded structure optical cable is similar to the traditional cable structure, so it is also called classical optical cable. The number of fibers that can be held by this kind of optical cable is generally 6 to 12 fibers, and there are also 24 fibers. With the increasing demand for the number of optical fibers, there is a unit stranding, that is, the optical fiber in the casing is not only one optical fiber core, but also multiple optical fiber cores, but also expands the number of optical fibers that the layer stranded optical cable can hold.

The layer stranded optical cable is easy to manufacture, the excess length of the optical fiber in the optical cable is easy to control, and the mechanical and environmental performance of the optical cable is good, which can be used for direct burying, pipeline and overhead laying.

Skeleton type: since it is called skeleton type, there is no doubt that there must be a part called skeleton in the optical cable. This kind of optical cable is to hold the optical fiber with the slot of the plastic skeleton. The cross section of the skeleton groove may be V-shaped, U-shaped and so on, and the longitudinal section may be spiral or sinusoidal. A skeleton slot can hold 5 "10 coated optical fibers.

The skeleton optical cable has good protection performance for optical fiber, good lateral compression strength, compact structure and small cable diameter, so it is suitable for pipeline layout. In addition, the density of optical fiber is high, up to thousands of cores. But the manufacture of skeleton fiber optic cable is complicated.

Bundle tube type: similar to the skeleton type optical cable, there is a large tube in the center of the bundle tube type optical cable, which is used to hold the optical fiber. This pipe is called a big casing. The coated optical fibers are loaded in the large casing, and the optical fibers are placed in the large casing without stranding. The reinforcing member layer is wound around the large casing.

This kind of optical cable has the advantages of simple structure and simple manufacturing process, and the protection of optical fiber is better than that of other structures, which can improve the stability of network transmission. The optical cable has small cross-sectional area and light weight, so it is especially suitable for overhead laying. The number of optical fibers in the bundle tube is flexible, but the number of optical fibers in the cable should not be too large.

Ribbon: the ribbon optical cable is named after the optical fiber contained in the optical cable as the ribbon optical fiber unit. Ribbon optical fiber unit is a rectangular optical fiber combination composed of several layers of ribbon optical fiber. Put the ribbon optical fiber unit into the large casing, that is, the bundle tube ribbon optical cable; put into the skeleton slot, it is the skeleton ribbon optical cable; put into the optical fiber casing and twist around the central reinforcement component, that is, the layer stranded ribbon optical cable. The schematic diagram of the bundle-tube ribbon cable is as follows:

The small size of the ribbon cable can increase the density of the fiber in the cable and accommodate more fiber cores, such as 320mm 3456 core. Ribbon optical cable is suitable for the rapid development of optical fiber access network.

What we often say about user optical cable, local telephone optical cable, long-distance optical cable and submarine optical cable is actually classified according to the different uses of optical cable. The corresponding relationship between these optical cables and the cable structure is as follows:

What do you mean by the model of optical cable? The appearance of the cable will be printed with English plus numeric symbols indicating the type of cable. What do you mean?

In China, the type naming of optical cable is regulated by the communication industry standard YD / T908-2011 of the people's Republic of China. The type of optical cable consists of three parts: type, specification and special performance identification, in which the special performance identification can be defaulted.

Note: types, specifications and special performance marks are separated by spaces.

The types and components of the optical cable are as follows:

The specifications of the optical cable are as follows:

The I (classification) meaning of the medium type of optical cable is shown in the following table:

Code name

Meaning

GY

Outdoor optical cable for communication

GYW

Miniature outdoor optical cable for communication

GYC

Miniature outdoor optical cable for communication

GYL

Laying fiber optic cable with microgrooves on outdoor road surface for communication

GYP

Outdoor rodent proof drainage pipe optical cable for communication

GJ

Indoor optical cable for communication

Air-blown miniature indoor optical cable for GJC communication

GJX

Indoor butterfly lead-in optical cable for communication

GJY communication indoor and outdoor fiber optic cable

Indoor and outdoor butterfly lead-in optical cable for GJYX communication

GH

Submarine optical cable for communication

GM

Mobile optical cable for communication

GS

Submarine optical cable for communication

GT

Special optical cable for communication

The meaning of medium-sized II (reinforcement) for optical cable models is shown in the following table:

Code name

Meaning is unsigned

Metal reinforced member

F

Non-metallic reinforced member

The meaning of medium-sized III (structural characteristics) of optical cable model is shown in the following table:

Structural feature type

Code meaning

Cable core fiber structure

Unsigned

Discrete optical fiber structure D optical fiber band structure

Secondary coating structure

Unsigned optical fiber loosely sheathed coated structure or uncoated structure

S

Optical fiber bundle structure

J

Optical fiber tightly sheathed coating structure

Loose casing material

Unsigned plastic loose casing or non-loose casing

M

Metal loose casing

Cable core structure

Unsigned stranded structure

G

Skeleton slot structure

X

Central tube structure

Water blocking structure

Unsigned

Full-dry or semi-dry

T

Filled structure

Load bearing structure

Unsigned non-self-bearing structure

C self-supporting structure

Cable material

Unsigned metal reinforced cable or non-cable

F

Non-metallic reinforced cable

Cross section shape

Unsigned circle

E

Ellipse shape

B Ellipse shape 8

The meaning of IV (sheath) for figure-8 optical cable models and medium-sized ones is shown in the following table:

Code name

Meaning

Y

Polyethylene sheath

V

Polyvinyl chloride sheath

U

Polyurethane sheath

H low smoke halogen free sheath

A

Aluminum-polyethylene adhesive sheath (A sheath for short)

S

Steel-polyethylene bonding sheath (S sheath for short)

F non-metallic fiber reinforced polyethylene adhesive sheath (F sheath for short)

W

Steel-polyethylene bonding sheath with steel wire (W sheath for short)

L

Aluminum sheath

G

Steel sheath

When the optical cable has an outer protective layer (that is, a type of V), the outer protective layer may contain some or all of the cushion, armor and outer coating, so V is represented by two sets of numbers. Each set of numbers may consist of one or two digits. The meaning of the type V (cover) is shown in the following table:

Group 1 (armoring layer)

The second group (outer coat or coat)

Code name

Meaning code

Meaning

0

Unarmored layer

Unsigned

No outer cover layer

1 steel pipe

1 fiber outer quilt

two

Double steel strip wrapped

2 polyvinyl chloride sleeve

three

Single thin round steel wire

3 polyethylene sleeve

33 double thin round steel wire

4 polyethylene sleeve with nylon sleeve

four

Single thick round steel wire

5 polyethylene protective cover

forty-four

Double thick round steel wire

6 Flame retardant polyethylene sleeve

five

Wrinkled steel strip

7 nylon sleeve with polyethylene sleeve

six

Non-metallic wire

-

-7 non-metallic belt

The specification of the type of optical cable consists of optical fiber, communication line and feeder, which are separated by "+". Communication lines and feeder lines can be all or part of the default.

The specification of optical fiber is composed of the number of optical fiber and the category of optical fiber. The category of optical fiber is shown in the classification table of optical fiber products. The number of optical fiber is expressed by the actual effective number of the same kind of optical fiber in the middle of optical cable. The optical fiber category code shall comply with the provisions of GB / T 12357 and GB / T 9771. The optical fiber category is shown in the following table:

Multimode optical fiber

Single mode optical fiber code

Meaning code

Meaning A1a.1

Silica graded index multimode fiber B1.1

Silica non-dispersive shifted single-mode fiber, namely G.652.A/ G.652.B fiber

A1a.2

B1.2

Silica cutoff wavelength shift single mode fiber, namely G.654 fiber

A1a.3

B1.3

Silica wavelength band extended non-dispersion shifted single-mode fiber, namely G.652.C fiber

A1b

B2

Silica dispersion shifted single mode fiber, i.e. G.653 fiber

A1d

B4a

Silica non-zero dispersion shift single mode fiber, namely G.655.A fiber

A2a~A2c

Silica abrupt refractive index multimode fiber

B4b

Silica non-zero dispersion shift single mode fiber, namely G.655.B fiber

A3a~A3c

Silica graded refractive index and plastic clad multimode optical fiber

B4c

Silica non-zero dispersion shift single mode fiber, namely G.655.C fiber

A4a~A4d

Abrupt refractive index plastic optical fiber

B4d

Silica non-zero dispersion shift single mode fiber, namely G.655.D fiber A4e

Graded or multi-order refractive index plastic optical fiber

B4e

Silica non-zero dispersion shift single mode fiber, namely G.655.E fiber A4f~A4h

Graded index plastic optical fiber

B5

Non-zero dispersion fiber for wide-wavelength optical transmission, that is, G.656 fiber

-

-

B6a1

Bend loss insensitive optical fiber for access network, namely G.657.A1 optical fiber

-- B6a2

Bend loss insensitive optical fiber for access network, namely G.657.A2 optical fiber

-- B6b2

Bend loss insensitive optical fiber for access network, namely G.657.B2 optical fiber

-- B6b3

Bend loss insensitive optical fiber for access network, namely G.657.B3 optical fiber

The composition of communication line specifications shall comply with the provisions of Table 3 in YD / T322-1996. For example: 2 × 2 × 0.4, which means 2 pairs of communication pairs with nominal diameter of 0.4mm.

The composition of feeder specifications shall be in accordance with Table 3 in YD / T 1173-2010. For example: 4 × 1.5, which means 4 pairs of feeder lines with a nominal cross-sectional area of 1.5mm2.

This will know the meaning of "GYFTA53" mentioned earlier, right? Guess What?

[answer: GY communication outdoor optical cable, F non-metallic reinforced member, T-filled structure (here represents structural features, several items are unsigned, we can't just look at the meaning of the letter T, we should add the unsigned structural meaning, so the complete meaning of structural features should be: loose layer strand filled structure), An aluminum-polyethylene adhesive sheath, 5 wrinkled steel tape armor, 3 polyethylene sheath]

How will the fiber optic cable develop in the future? The structure of optical cable develops with the development of optical network and the requirement of service environment. The new generation of all-optical network requires optical cables to provide wider bandwidth, accommodate more wavelengths, transmit higher rates, facilitate installation and maintenance, longer service life, and so on. The emergence of new materials for optical cable has promoted the improvement of optical cable structure, such as the use of dry water-resistant materials, nano-materials, flame retardant materials, etc., so that the performance of optical cable has been significantly improved. In recent years, new optical cables have emerged, such as ecological optical cable, nanotechnology optical cable, miniature optical cable and so on.

Ecological optical cable: mainly from the point of view of environmental protection, to solve the problem of non-environmentally friendly materials in optical cable, such as toxic gas released by PVC combustion and lead in optical cable stabilizer. This kind of optical cable is mainly used indoors, buildings and families. At present, some companies have produced some new materials for this kind of optical cable, such as halogen-free flame retardant plastics.

Nanotechnology optical cables: optical cables using nano-materials (such as nano-fiber coatings, nano-fiber ointment, nano-sheath polyethylene, fiber-optic sheath nano-PBT) take advantage of many excellent properties of nano-materials, such as improving the mechanical impact resistance of optical cables.

Miniature optical cable: miniature optical cable is mainly to cooperate with the application of air pressure or water pressure installation and construction system. All kinds of miniature optical cable structures have been designed and used, which requires a certain coefficient between optical cable and pipeline. The weight of the optical cable should be accurate and have a certain hardness. Miniature optical cable and automatic installation are designed to meet the needs of the future access network, especially the integrated wiring system in the customer premises network and the wiring in the intelligent pipelines of intelligent buildings.

To sum up, with the development of higher technology of optical network, optical cable continues to improve in structure, new materials and performance, in order to meet the diverse needs of future communications, such as the needs of massive data carrying and massive connections in 5G era.

This article comes from the official account of Wechat: ZTE documents (ID:ztedoc)

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