The most widely used txuas xov tooj in surveillance thiab kev ruaj ntseg projects include coaxial txuas xov tooj, twisted pairs, thiaboptical fibers. The following are the main points of knowledge about the usage methods and functions of these commonly used txuas xov tooj, thiab raws li qhov sib txawv ntawm lawv.
Coaxial cable 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, thiablow price. It is also widely used, such as closed-circuit television lines. Coaxial thin txuas xov tooj are generally sold at a few yuan per meter in the market, which is not too expensive. Coaxial txuas xov tooj are used to connect with BNC connectors. The coaxial txuas xov tooj 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, thiabcan 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 txuas xov tooj 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 txuas xov tooj still have some shortcomings in the transmission of image signals in the monitoring system:
1) Cov coaxial cable nws tus kheej tau cuam tshuam ntau yam los ntawm kev hloov huab cua, thiab cov duab zoo tau cuam tshuam rau qee yam;
2) Cov coaxial cable yog tus tuab, uas tsis yooj yim rau cov xov hlau hauv cov ntawv thov tuab;
3) Coaxial txuas xov tooj 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) Coaxial cable has limited anti-interference ability and cannot be siv nyob rau hauvstrong interference environment;
5) Cov coaxial amplifier tseem muaj qhov tsis zoo ntawm qhov nyuaj hauv kev hloov kho.
2.Ethernet Cable Sib ntswg cable
5) CAT5 cable: This type of cable has increased winding density, a high-quality insulation material, thiaba 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 txuas xov tooj.
6) CAT5 cable: CAT5 has low attenuation, less crosstalk, higher attenuation to crosstalk ratio (ACR), signal-to-noise ratio (Structural Return Loss), smaller delay error, thiabperformance Greatly improved. The maximum transmission rate of CAT5E cable is 250Mbps.
7) CAT6 cable: Kev xa tawm zaus ntawm hom ntawm cable no yog 1MHz～250MHz, thiabthe 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 CAT5 bandwidth. The transmission performance of Category 6 cabling is much higher than that of the Super Category 5 standard, thiabis most suitable for applications with a transmission rate higher than 1Gbps.
An important difference between CAT6 and CAT5 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, thiabthe wiring standard adopts a star-shaped topology. The required wiring distance is: the length of the permanent link cannot exceed 90m, thiabthe channel length cannot exceed 100m.
8)CAT6A Cable: CAT6A 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 siv nyob rau hauvgigabit networks. In terms of transmission frequency, it is also 200-250 MHz like Category 6 lines, thiabthe 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) CAT7 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 CAT 6 and CAT6A txuas xov tooj. Up to 10 Gbps.
3. Optical fiber
Optical fiber (Fiber Optic Cable) xa cov teeb liab nyob rau hauv daim ntawv ntawm lub teeb pulses, yog li ntawd cov khoom siv mas yog iav lossis plexiglass. Nws muaj qhov tseem ceeb ntawm fiber ua tub ntxhais, sau daim phiaj thiab lub hau npog pov hwm.
The structure of the optical fiber is very similar to that of a coaxial cable, thiabthe center is an optical fiber made of glass or transparent plastic, surrounded by a protective material, thiabmultiple 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, thiabis 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 siv nyob rau hauvgeneral applications.
The biggest feature of optical fiber is that it conducts optical signals, so it is not interfered by external electromagnetic signals, thiabthe signal attenuation speed is very slow, so the signal transmission distance is much longer than the above various network txuas xov tooj that transmit electrical signals, thiabit is especially suitable for Places with harsh electromagnetic environment.
Vim tias qhov kho qhov muag ntawm cov xim kho qhov muag, ntau lub teeb liab tuaj yeem sib kis tau tib lub sijhawm sab hauv cov kab hluav taws xob, yog li cov kev sib kis ceev ntawm cov hluav taws xob fiber ntau tuaj yeem ua tau zoo heev. Tam sim no, 1Gbps 1000Mbps optical network network tau dhau los ua lub ntsiab hluav taws xob hauv high-speed network. Raws li txoj kev xav, lub network fiber ntau tau txog li 50000Gbps 50Tbps. nrawm.