As we all know, the sharpness and distortion of an image are very important in a surveillance system, and determining the sharpness and distortion of an image requires not only basic equipment such as cameras, lenses, monitors, and video recorders capable of processing high-quality images, but also the transmission of signal data. It is also very important. The choice of which transmission medium to transmit the signal directly relates to the quality and reliability of the entire monitoring system.
At present, there are mainly three types of transmission media used to transmit image signals in monitoring systems: coaxial cables, twisted-pair cables, and optical fibers. These three transmission media are different from each other, and each has its own advantages and disadvantages. How should we choose when monitoring and wiring, which can not only reduce the cost, but also make the monitoring system have a very high quality and reliability?
Coaxial cable: It has the advantage of being cheaper and easier to lay (as opposed to an optical fiber). Therefore, in a small-scale surveillance system, since the transmission distance is very short, the monitor image is directly transmitted using the coaxial cable. The damage of the image quality is not large enough to meet actual requirements. However, according to the analysis of the characteristics of the coaxial cable itself, when the signal is transmitted in the coaxial cable, its attenuation is related to the transmission distance and the frequency of the signal itself. In general, the higher the signal frequency, the greater the attenuation.
The bandwidth of the video signal is very large, reaching 6mhz, and the color part of the image is modulated at the high end of the frequency. Thus, when the video signal is transmitted in the coaxial cable, not only the overall amplitude of the signal is attenuated, but also the attenuation of each frequency component is greatly different. In particular, the attenuation of the color part is the greatest. Therefore, the coaxial cable is only suitable for transmitting the image signal at a short distance. When the transmission distance reaches about 200 meters, the image quality will obviously decrease, especially the color becomes dull, and there is a sense of distortion. However, the relative cost of the coaxial cable is relatively low, so it is suitable for analog camera monitoring in small factories or schools.
Twisted pair: Compared to coaxial cable twisted pair transmission distance is much larger, up to 2400 meters, its cheap and easy access, anti-interference ability is not bad, the use of poe power supply can also reduce the task of integrated wiring . However, the anti-aging ability of twisted pair materials is weak, and only one image can be transmitted at a time. Therefore, it is more suitable for the video surveillance of network cameras under medium and short distances, and the cameras are relatively dispersed, and not many or near but relatively concentrated, such as banks, hotel chains, supermarkets or university campuses.
Fiber: The advantages of fiber transmission are: long transmission distance, high speed, high bandwidth, low attenuation, and best anti-jamming performance. It is suitable for long-distance and large-scale video transmission, such as road crossroad monitoring. It can even reach tens of more than 100 kilometers at the furthest distance. It is transmitted through optical fibers by converting video and control signals into optical signals.
Its optical fiber transmission equipment is mainly video optical transceiver and optical fiber transceiver. Video optical transceiver is mainly used in the analog camera signal transmission, it has small signal loss, small noise and distortion, high transmission quality, suitable for long distance transmission. Fiber optic transceivers are suitable for network camera signal transmission. It also has the advantages of long distance, low loss and strong anti-interference ability of video optical transceivers. With fiber-optic switches, poe technology can also be used to power the front-end cameras, reducing the amount of integrated wiring tasks. Therefore, optical fiber is the best way to solve long-distance transmission.
However, the use of optical fiber and optical transceivers requires a certain amount of expertise and special equipment, which brings certain difficulties for construction and user use. In addition, for short-range, small-scale monitoring systems, the use of optical fiber transmission is also not economical.
In summary, we need to decide on the monitoring system's cabling selection based on our monitoring environment and monitoring distance requirements. When cabling, multiple considerations need to be taken to select the optimal solution so that we can reduce costs. Input, but also play a good monitoring effect.
At present, there are mainly three types of transmission media used to transmit image signals in monitoring systems: coaxial cables, twisted-pair cables, and optical fibers. These three transmission media are different from each other, and each has its own advantages and disadvantages. How should we choose when monitoring and wiring, which can not only reduce the cost, but also make the monitoring system have a very high quality and reliability?
Coaxial cable: It has the advantage of being cheaper and easier to lay (as opposed to an optical fiber). Therefore, in a small-scale surveillance system, since the transmission distance is very short, the monitor image is directly transmitted using the coaxial cable. The damage of the image quality is not large enough to meet actual requirements. However, according to the analysis of the characteristics of the coaxial cable itself, when the signal is transmitted in the coaxial cable, its attenuation is related to the transmission distance and the frequency of the signal itself. In general, the higher the signal frequency, the greater the attenuation.
The bandwidth of the video signal is very large, reaching 6mhz, and the color part of the image is modulated at the high end of the frequency. Thus, when the video signal is transmitted in the coaxial cable, not only the overall amplitude of the signal is attenuated, but also the attenuation of each frequency component is greatly different. In particular, the attenuation of the color part is the greatest. Therefore, the coaxial cable is only suitable for transmitting the image signal at a short distance. When the transmission distance reaches about 200 meters, the image quality will obviously decrease, especially the color becomes dull, and there is a sense of distortion. However, the relative cost of the coaxial cable is relatively low, so it is suitable for analog camera monitoring in small factories or schools.
Twisted pair: Compared to coaxial cable twisted pair transmission distance is much larger, up to 2400 meters, its cheap and easy access, anti-interference ability is not bad, the use of poe power supply can also reduce the task of integrated wiring . However, the anti-aging ability of twisted pair materials is weak, and only one image can be transmitted at a time. Therefore, it is more suitable for the video surveillance of network cameras under medium and short distances, and the cameras are relatively dispersed, and not many or near but relatively concentrated, such as banks, hotel chains, supermarkets or university campuses.
Fiber: The advantages of fiber transmission are: long transmission distance, high speed, high bandwidth, low attenuation, and best anti-jamming performance. It is suitable for long-distance and large-scale video transmission, such as road crossroad monitoring. It can even reach tens of more than 100 kilometers at the furthest distance. It is transmitted through optical fibers by converting video and control signals into optical signals.
Its optical fiber transmission equipment is mainly video optical transceiver and optical fiber transceiver. Video optical transceiver is mainly used in the analog camera signal transmission, it has small signal loss, small noise and distortion, high transmission quality, suitable for long distance transmission. Fiber optic transceivers are suitable for network camera signal transmission. It also has the advantages of long distance, low loss and strong anti-interference ability of video optical transceivers. With fiber-optic switches, poe technology can also be used to power the front-end cameras, reducing the amount of integrated wiring tasks. Therefore, optical fiber is the best way to solve long-distance transmission.
However, the use of optical fiber and optical transceivers requires a certain amount of expertise and special equipment, which brings certain difficulties for construction and user use. In addition, for short-range, small-scale monitoring systems, the use of optical fiber transmission is also not economical.
In summary, we need to decide on the monitoring system's cabling selection based on our monitoring environment and monitoring distance requirements. When cabling, multiple considerations need to be taken to select the optimal solution so that we can reduce costs. Input, but also play a good monitoring effect.
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