The most widely used каблови in surveillance и сигурност projects include coaxial каблови, twisted pairs, иoptical fibers. The following are the main points of knowledge about the usage methods and functions of these commonly used каблови, као и разлике међу њима.
Коаксијални кабл 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, иlow price. It is also widely used, such as closed-circuit television lines. Coaxial thin каблови are generally sold at a few yuan per meter in the market, which is not too expensive. Coaxial каблови are used to connect with BNC connectors. The coaxial каблови 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, иcan 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 каблови 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 каблови still have some shortcomings in the transmission of image signals in the monitoring system:
1) Климатске промене у великој мери утичу на сам коаксијални кабл, а на квалитет слике утиче у одређеној мери;
2) Коаксијални кабл је релативно дебео, што није погодно за ожичење у густим апликацијама за надгледање;
3) Coaxial каблови 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) Коаксијални кабл has limited anti-interference ability and cannot be се користи уstrong interference environment;
5) Коаксијално појачало такође има недостатак због потешкоћа у подешавању.
2Етернет кабал Увијени кабл
5) CАТ5 cable: This type of cable has increased winding density, a high-quality insulation material, иa 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 каблови.
6) CАТ5 cable: CАТ5 has low attenuation, less crosstalk, higher attenuation to crosstalk ratio (ACR), signal-to-noise ratio (Structural Return Loss), smaller delay error, иperformance Greatly improved. The maximum transmission rate of CАТ5E cable is 250Mbps.
7) CАТ6 cable: The transmission frequency of this type of cable is 1MHz～250MHz, иthe 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 CАТ5 bandwidth. The transmission performance of Category 6 cabling is much higher than that of the Super Category 5 standard, иis most suitable for applications with a transmission rate higher than 1Gbps.
An important difference between CАТ6 and CАТ5 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, иthe wiring standard adopts a star-shaped topology. The required wiring distance is: the length of the permanent link cannot exceed 90m, иthe channel length cannot exceed 100m.
8)CАТ6A Cable: CАТ6A 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 се користи уgigabit networks. In terms of transmission frequency, it is also 200-250 MHz like Category 6 lines, иthe 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) CАТ7 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 CАТ 6 and CАТ6A каблови. Up to 10 Gbps.
3. Оптичко влакно
Оптичко влакно (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, иthe center is an optical fiber made of glass or transparent plastic, surrounded by a protective material, иmultiple 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, иis 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 се користи уgeneral applications.
The biggest feature of optical fiber is that it conducts optical signals, so it is not interfered by external electromagnetic signals, иthe signal attenuation speed is very slow, so the signal transmission distance is much longer than the above various network каблови that transmit electrical signals, иit is especially suitable for Places with harsh electromagnetic environment.
Због карактеристика оптичке рефлексије оптичких влакана, истовремено се може преносити више сигнала унутар оптичког влакна, тако да брзина преноса оптичког влакна може бити врло велика. Тренутно је мрежа оптичких влакана 1Гбпс 1000Мбпс постала главна мрежа великих брзина. Теоретски, мрежа оптичких влакана може достићи до 50000Гбпс 50Тбпс. брзина.