The most widely used kábelek in surveillance és a biztonság projects include coaxial kábelek, twisted pairs, ésoptical fibers. The following are the main points of knowledge about the usage methods and functions of these commonly used kábelek, valamint a köztük lévő különbségek.
Koaxiális kábel 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, éslow price. It is also widely used, such as closed-circuit television lines. Coaxial thin kábelek are generally sold at a few yuan per meter in the market, which is not too expensive. Coaxial kábelek are used to connect with BNC connectors. The coaxial kábelek 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, éscan 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 kábelek 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 kábelek still have some shortcomings in the transmission of image signals in the monitoring system:
1) Magát a koaxiális kábelt nagymértékben befolyásolja az éghajlatváltozás, és a kép minőségét bizonyos mértékben befolyásolja;
2) A koaxiális kábel viszonylag vastag, ami sűrű monitorozási alkalmazásoknál nem kényelmes a huzalozáshoz;
3) Coaxial kábelek 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) Koaxiális kábel has limited anti-interference ability and cannot be használtstrong interference environment;
5) A koaxiális erősítő hátránya, hogy nehezen állítható be.
2.Hálózati kábel Csavart kábel
5) CNÁL NÉL5 cable: This type of cable has increased winding density, a high-quality insulation material, ésa 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 kábelek.
6) CNÁL NÉL5 cable: CNÁL NÉL5 has low attenuation, less crosstalk, higher attenuation to crosstalk ratio (ACR), signal-to-noise ratio (Structural Return Loss), smaller delay error, ésperformance Greatly improved. The maximum transmission rate of CNÁL NÉL5E cable is 250Mbps.
7) CNÁL NÉL6 cable: The transmission frequency of this type of cable is 1MHz～250MHz, ésthe 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 CNÁL NÉL5 bandwidth. The transmission performance of Category 6 cabling is much higher than that of the Super Category 5 standard, ésis most suitable for applications with a transmission rate higher than 1Gbps.
An important difference between CNÁL NÉL6 and CNÁL NÉL5 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, ésthe wiring standard adopts a star-shaped topology. The required wiring distance is: the length of the permanent link cannot exceed 90m, ésthe channel length cannot exceed 100m.
8)CNÁL NÉL6A Cable: CNÁL NÉL6A 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 használtgigabit networks. In terms of transmission frequency, it is also 200-250 MHz like Category 6 lines, ésthe 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) CNÁL NÉL7 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 CNÁL NÉL 6 and CNÁL NÉL6A kábelek. Up to 10 Gbps.
3. Optikai szál
Optikai szál (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, ésthe center is an optical fiber made of glass or transparent plastic, surrounded by a protective material, ésmultiple 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, ésis 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 használtgeneral applications.
The biggest feature of optical fiber is that it conducts optical signals, so it is not interfered by external electromagnetic signals, ésthe signal attenuation speed is very slow, so the signal transmission distance is much longer than the above various network kábelek that transmit electrical signals, ésit is especially suitable for Places with harsh electromagnetic environment.
Az optikai szál optikai visszaverődésének jellemzői miatt az optikai szál belsejében egyszerre több jel is továbbítható, így az optikai szál átviteli sebessége nagyon magas lehet. Jelenleg az 1Gbps 1000Mbps optikai hálózattá vált a mainstream nagy sebességű hálózat. Elméletileg az optikai szálas hálózat elérheti az 50000Gbps 50Tbps sebességet. sebesség.