1. Video baseband transmission: The most traditional television monitoring transmission method does not do any processing on 0 to 6 MHz video baseband signals, and directly transmits analog signals through coaxial cables (unbalanced).
Advantages: Small loss of image signals transmitted over short distances, low cost, and stable system.
Disadvantages: The transmission distance is short, high-frequency component attenuation is more than 300 meters, and the image quality cannot be guaranteed. Large amount of wiring, difficult maintenance, poor scalability, suitable for small systems. In particular, nowadays, non-standard wire is prevalent. When you find that there is video interference, after the matrix is ​​added, the character jumps. After the screen is disturbed by the video splitter, can you use the cable to meet the standard?
2. Optical fiber transmission: Common analog optical transceivers and digital optical transceivers are the best solutions to solve tens or even hundreds of kilometers of television monitoring transmissions. They convert the video and control signals into laser signals for transmission in optical fibers.
Advantages: long transmission distance, low attenuation, best anti-interference performance, suitable for long-distance transmission. Standard optical transceivers are 0---20 kilometers transmission distance, 8 optical transceivers are the most cost-effective, this is related to bald, and friends who do Guangduan know. Optical transceivers are now cheap, but they are still very expensive.
Disadvantages: The transmission of monitoring signals within a few kilometers is not economical; optical welding and maintenance require professional technicians and equipment to operate and process, and maintenance technology requirements are high, so it is not easy to upgrade and expand capacity. In order to save the cheap optical jumpers and flanges, some engineering personnel directly connected the fiber pigtails. After the maintenance, you will know how important the jumpers and flanges are.
3, network transmission: to solve the long-distance metropolitan area, the location of a very scattered monitoring transmission, using MPEG2/4, H.264 audio and video compression format to transmit monitoring signals.
Advantages: The use of network video server as a monitoring signal upload device, Internet monitoring software can be installed on the remote monitoring and control.
Disadvantages: limited by the network bandwidth and speed, can only transmit a small picture, low quality image; can only transfer a few to a dozen frames per second, the animation is very obvious and there is a delay, can not be real-time monitoring. However, I am very optimistic about network transmission.
4. Twisted-pair transmission (balanced transmission): It is also a type of video baseband transmission. It converts the 75-ohm unbalanced mode to balanced mode for transmission. It is one of the solutions to solve the problem of the transmission of electromagnetic signals in the 1Km monitoring image, and the monitoring image signal processing is transmitted in a balanced and symmetrical manner.
Advantages: Easy wiring, low cost, strong anti-common mode performance.
Disadvantages: Can only solve the 1Km monitoring image transmission, and a twisted pair can only transmit one image, not suitable for application in large and medium-sized monitoring; Twisted-pair texture weak anti-aging ability, not suitable for field transmission; twisted pair The transmission of high-frequency components is greatly attenuated, and the color of the image is greatly lost.
5, a total of cable transmission: video using AM modulation, FSK data modulation and other technologies, dozens of monitoring images, audio, control and alarm signals integrated into the "one" coaxial cable in two-way transmission. To put it plainly, the cable television network is backwards. It is completely a closed-circuit television transmission technology. It is mature and very practical.
Advantages: Make full use of the coaxial cable's resource space, 20-way audio and video and control signals are transmitted in two directions on the same cable to achieve "one-line access," simple construction, easy maintenance, substantial savings in material costs and construction costs; frequency division The multiplexing technology solves the problem of dispersion of distant transmission points and the difficulty in monitoring and transmission of wiring. The RF transmission mode only attenuates the carrier signal, and the attenuation of the image signal is very small. Simultaneous nesting of luminance and chrominance transmission ensures that the image quality reaches the national standard above 4; The use of 75Ω coaxial non-equilibrium transmission makes it have a very strong anti-interference ability, and the electromagnetic environment can still guarantee image quality in complex applications.
Disadvantages: The use of cable television transmission technology is a joint project. It's a bit of a cross-industry for friends who do monitoring. The total cable transmission is mainly for designing this piece. Of course, there are layers for products. Many things in RF are still very important in experience. System debugging requires high technology and professional instruments must be used.
Advantages: Small loss of image signals transmitted over short distances, low cost, and stable system.
Disadvantages: The transmission distance is short, high-frequency component attenuation is more than 300 meters, and the image quality cannot be guaranteed. Large amount of wiring, difficult maintenance, poor scalability, suitable for small systems. In particular, nowadays, non-standard wire is prevalent. When you find that there is video interference, after the matrix is ​​added, the character jumps. After the screen is disturbed by the video splitter, can you use the cable to meet the standard?
2. Optical fiber transmission: Common analog optical transceivers and digital optical transceivers are the best solutions to solve tens or even hundreds of kilometers of television monitoring transmissions. They convert the video and control signals into laser signals for transmission in optical fibers.
Advantages: long transmission distance, low attenuation, best anti-interference performance, suitable for long-distance transmission. Standard optical transceivers are 0---20 kilometers transmission distance, 8 optical transceivers are the most cost-effective, this is related to bald, and friends who do Guangduan know. Optical transceivers are now cheap, but they are still very expensive.
Disadvantages: The transmission of monitoring signals within a few kilometers is not economical; optical welding and maintenance require professional technicians and equipment to operate and process, and maintenance technology requirements are high, so it is not easy to upgrade and expand capacity. In order to save the cheap optical jumpers and flanges, some engineering personnel directly connected the fiber pigtails. After the maintenance, you will know how important the jumpers and flanges are.
3, network transmission: to solve the long-distance metropolitan area, the location of a very scattered monitoring transmission, using MPEG2/4, H.264 audio and video compression format to transmit monitoring signals.
Advantages: The use of network video server as a monitoring signal upload device, Internet monitoring software can be installed on the remote monitoring and control.
Disadvantages: limited by the network bandwidth and speed, can only transmit a small picture, low quality image; can only transfer a few to a dozen frames per second, the animation is very obvious and there is a delay, can not be real-time monitoring. However, I am very optimistic about network transmission.
4. Twisted-pair transmission (balanced transmission): It is also a type of video baseband transmission. It converts the 75-ohm unbalanced mode to balanced mode for transmission. It is one of the solutions to solve the problem of the transmission of electromagnetic signals in the 1Km monitoring image, and the monitoring image signal processing is transmitted in a balanced and symmetrical manner.
Advantages: Easy wiring, low cost, strong anti-common mode performance.
Disadvantages: Can only solve the 1Km monitoring image transmission, and a twisted pair can only transmit one image, not suitable for application in large and medium-sized monitoring; Twisted-pair texture weak anti-aging ability, not suitable for field transmission; twisted pair The transmission of high-frequency components is greatly attenuated, and the color of the image is greatly lost.
5, a total of cable transmission: video using AM modulation, FSK data modulation and other technologies, dozens of monitoring images, audio, control and alarm signals integrated into the "one" coaxial cable in two-way transmission. To put it plainly, the cable television network is backwards. It is completely a closed-circuit television transmission technology. It is mature and very practical.
Advantages: Make full use of the coaxial cable's resource space, 20-way audio and video and control signals are transmitted in two directions on the same cable to achieve "one-line access," simple construction, easy maintenance, substantial savings in material costs and construction costs; frequency division The multiplexing technology solves the problem of dispersion of distant transmission points and the difficulty in monitoring and transmission of wiring. The RF transmission mode only attenuates the carrier signal, and the attenuation of the image signal is very small. Simultaneous nesting of luminance and chrominance transmission ensures that the image quality reaches the national standard above 4; The use of 75Ω coaxial non-equilibrium transmission makes it have a very strong anti-interference ability, and the electromagnetic environment can still guarantee image quality in complex applications.
Disadvantages: The use of cable television transmission technology is a joint project. It's a bit of a cross-industry for friends who do monitoring. The total cable transmission is mainly for designing this piece. Of course, there are layers for products. Many things in RF are still very important in experience. System debugging requires high technology and professional instruments must be used.
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