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Introducerea mai multor cabluri comune utilizate în supraveghere și securitate

2021-02-04

Introducerea mai multor cabluri comune folosit inSupraveghereși securitate

The most widely used cabluri in surveillance și securitate projects include coaxial cabluri, twisted pairs, șioptical fibers. The following are the main points of knowledge about the usage methods and functions of these commonly used cabluri, precum și diferențele dintre ele.

 

1. Cablu coaxial

 

 

Cablu coaxial is a cable with a central copper conductor wrapped in layers of insulated wires. It is characterized by good anti-interference ability, stable data transmission, șilow price. It is also widely used, such as closed-circuit television lines. Coaxial thin cabluri are generally sold at a few yuan per meter in the market, which is not too expensive. Coaxial cabluri are used to connect with BNC connectors. The coaxial cabluri sold on the market are generally finished products that have been connected with BNC connectors.

 

In engineering practice, in order to extend the transmission distance, a coaxial amplifier is used. The coaxial amplifier can amplify the video signal to a certain extent, șican also compensate different frequency components in different sizes through equalization adjustment, so as to minimize the distortion of the video signal output by the receiving end. However, coaxial amplifiers cannot be cascaded indefinitely. Generally, only 2 to 3 coaxial amplifiers can be cascaded in a point-to-point system. Otherwise, the video transmission quality cannot be guaranteed and adjustment is difficult. Therefore, when using coaxial cabluri in a monitoring system, in order to ensure a better image quality, the transmission distance range is generally limited to about 400-500 meters.

In addition, coaxial cabluri still have some shortcomings in the transmission of image signals in the monitoring system:

1) Cablul coaxial în sine este foarte afectat de schimbările climatice, iar calitatea imaginii este afectată într-o anumită măsură;

2) Cablul coaxial este relativ gros, ceea ce nu este convenabil pentru cablare în aplicații de monitorizare densă;

3) Coaxial cabluri generally can only transmit video signals. If the system needs to transmit control data, audio and other signals at the same time, additional wiring is required;

4) Cablu coaxial has limited anti-interference ability and cannot be folosit instrong interference environment;

5) Amplificatorul coaxial are, de asemenea, dezavantajul dificultății de reglare.

 

2.Cablu Ethernet Cablu răsucit

 

Common twisted-pair cabluri are CLA 5șiCLA 5E, CLA6, șiCLA7. Primul are un diametru subțire al firului, iar cel din urmă are un diametru gros al firului. Modelele sunt după cum urmează:

 

5) CLA 5 cable: This type of cable has increased winding density, a high-quality insulation material, șia transmission rate of 100MHz. It is used for voice transmission and data transmission with a maximum transmission rate of 100Mbps. It is mainly used for 100BASE-T and 10BASE-T network. This is the most commonly used Ethernet cabluri.

6) CLA 5 cable: CLA 5 has low attenuation, less crosstalk, higher attenuation to crosstalk ratio (ACR), signal-to-noise ratio (Structural Return Loss), smaller delay error, șiperformance Greatly improved. The maximum transmission rate of CLA 5E cable is 250Mbps.

7) CLA6 cable: The transmission frequency of this type of cable is 1MHz250MHz, șithe comprehensive attenuation crosstalk ratio (PS-ACR) of Category 6 wiring system should have a larger margin at 200MHz. It provides two times the power of CLA 5 bandwidth. The transmission performance of Category 6 cabling is much higher than that of the Super Category 5 standard, șiis most suitable for applications with a transmission rate higher than 1Gbps.

 

An important difference between CLA6 and CLA 5 is: improved crosstalk and return loss performance. For a new generation of full-duplex high-speed network applications, excellent return loss performance is extremely important. The basic link model is canceled in the six types of standards, șithe wiring standard adopts a star-shaped topology. The required wiring distance is: the length of the permanent link cannot exceed 90m, șithe channel length cannot exceed 100m.

8)CLA6A Cable: CLA6A Cable is an improved version of Category 6, which is also an unshielded twisted pair cable specified in ANSI/EIA/TIA-568B.2 and ISO Category 6/Class E standards. Mainly folosit ingigabit networks. In terms of transmission frequency, it is also 200-250 MHz like Category 6 lines, șithe maximum transmission speed can also reach 1 000 Mbps, but it is greatly improved in terms of crosstalk, attenuation and signal-to-noise ratio.

9) CLA7 Cable: This line is the latest twisted pair in the ISO 7/F standard. It is mainly used to adapt to the application and development of 10 Gigabit Ethernet technology. But it is no longer an unshielded twisted pair, but a shielded twisted pair, so its transmission frequency can reach at least 500 MHz, which is more than twice that of CLA 6 and CLA6A cabluri. Up to 10 Gbps.

 

 

3. Fibra optica

Fibra optica (Fiber Optic Cable) transmits signals in the form of light pulses, so the material is mainly glass or plexiglass. It consists of a fiber core, a cladding and a protective cover.

 

The structure of the optical fiber is very similar to that of a coaxial cable, șithe center is an optical fiber made of glass or transparent plastic, surrounded by a protective material, șimultiple optical fibers can be combined in one optical cable as needed. According to different optical signal generation methods, optical fibers can be divided into single-mode fibers and multi-mode fibers. To

 

Multimode fiber is generally used for network connections in the same office building or in a relatively close area. The single-mode optical fiber transmits data with higher quality and longer transmission distance, șiis usually used to connect office buildings or geographically dispersed networks. If optical fiber and cable are used as the network transmission medium, it is necessary to add equipment such as optical transceivers, so the cost investment is greater and it is less folosit ingeneral applications.

 

The biggest feature of optical fiber is that it conducts optical signals, so it is not interfered by external electromagnetic signals, șithe signal attenuation speed is very slow, so the signal transmission distance is much longer than the above various network cabluri that transmit electrical signals, șiit is especially suitable for Places with harsh electromagnetic environment.

 

Datorită caracteristicilor de reflexie optică ale fibrelor optice, semnale multiple pot fi transmise în același timp în interiorul unei fibre optice, astfel încât viteza de transmisie a fibrei optice poate fi foarte mare. În prezent, rețeaua de fibră optică de 1 Gbps 1000 Mbps a devenit rețeaua principală de mare viteză. Teoretic, rețeaua de fibră optică poate ajunge până la 50000Gbps 50Tbps. viteză.