A video optical transceiver is a device that converts one or more analog video signals into optical signals through optical fibers through various encodings. Since the video signal is converted into an optical signal, it passes both analog and digital conversion technologies. Video optical transceivers are divided into analog optical transceivers and digital optical transceivers.
1) Analogue optical transceiver The analog optical transceiver adopts PFM modulation technology to transmit image signals in real time, and is currently used more often. The transmit end first performs the PFM modulation on the analog video signal, and then performs the electro-optical conversion. After the optical signal is transmitted to the receiving end, the optical-electrical conversion is performed, and then the PFM demodulation is performed to recover the video signal. Due to the adoption of PFM modulation technology, the transmission distance can easily reach around 30 Km, and the transmission distance of some products can reach 80 Km or even hundreds of kilometers. Moreover, the image signal has little distortion after transmission, and has a high signal-to-noise ratio and little nonlinear distortion. By using wavelength division multiplexing technology, it is also possible to realize bi-directional transmission of image and data signals on a single optical fiber to meet the actual needs of the monitoring project. This analog optical transceiver also has some drawbacks:
a) production debugging is more difficult;
b) It is more difficult for a single optical fiber to achieve multi-channel image transmission, and its performance will be degraded. At present, this analog optical transceiver generally can only transmit 4 channels of images on a single optical fiber;
c) Due to the use of analog modulation and demodulation technology, its stability is not high enough. With the increase of the use time or the change of the environment characteristics, the performance of the optical transceiver will also change, which will cause some inconvenience for the use of the project.
2) Digital Optical Multiplexer Since digital technology has obvious advantages in many aspects compared with traditional analog technologies, just as digital technology has replaced analog technology in many fields, the digitalization of optical transceivers is also an inevitable trend. At present, digital image optical transceivers mainly have two technical methods: one is an MPEG II image compression digital optical transceiver, and the other is a non-compressed digital image optical transceiver. Image compression digital optical transceivers generally use MPEG II image compression technology, which can compress moving images into N×2 Mbps data streams and transmit them over standard telecommunications interfaces or directly over optical fibers. Due to the use of image compression technology, it can greatly reduce the signal transmission bandwidth.
The question of how to select the right video optical transceiver for the selection of video optical transceivers is in front of everyone. Here, we would like to share our years of industry experience with readers who are interested in the selection of video optical transceivers. Optics purchase considerations Analog signals; digital signals < From the signals sent to the optical fiber, optical transceivers can be divided into analog optical transceivers based on analog technology and analog optical transceivers based on digital technology. The working principle of analog optical transceiver is nothing more than modulation, demodulation, filtering and signal mixing. Regardless of whether it is an LED or an LD, its photoelectric modulation characteristics are not linear. Inevitably, problems such as distortion and interference are inevitable in the signal transmission process, and there are insurmountable technologies in terms of large-capacity transmission and multi-service mixed transmission. difficulty.
With the development of the times and the increasing requirements of users for security precautions, surveillance optical transceivers have been more and more widely used in the field of security, and the technology for monitoring optical transceivers has become more and more mature, so the current monitoring optical transceivers can already be realized in one core. Multiple signals such as video, audio, data, telephone, Ethernet, and alarm are transmitted on the optical fiber.
Monitor the optical transmission medium and its characteristics:
The medium used to monitor the optical transceiver is optical fiber. So why choose to transmit it through optical fiber? The main component of the optical fiber is silicon dioxide (SiO2), which accounts for a large proportion of the minerals in the entire earth and can usually be extracted from stones and sand. Fibers made of silicon dioxide (SiO2) are brittle as glass and fine as hair. From its internal composition, optical fibers are classified into single-mode fibers and multi-mode fibers. The core diameter of single-mode fibers is 9 μm, and the core diameter of multi-mode fibers can be divided into 50 μm and 62.5 μm. Because of the composition of the optical fiber, it has the characteristics of long transmission distance, non-conductivity, strong anti-interference ability and good confidentiality. In the long-distance transmission, it is usually the first choice of the majority of engineering companies.
Other attachments:
1. The optical jumper is mainly used for connection. It connects the optical transceiver and the optical fiber. Then, from the perspective of the connectors at both ends of the optical jumper, the optical jumpers are divided into FC jumpers, ST jumpers, and SC jumpers; from the perspective of the optical jumpers, they can be divided into 3m jumpers, 5m Jumpers, 10m jumpers, etc.
2. The terminal box The terminal box, also known as the welding box, is mainly to protect the fusion joint between the optical jumper and the optical fiber. The optical fiber and the jumper are welded into the terminal box through the optical fiber fusion splicer. In general, one terminal box is required for each optical transmitter in the front end, and only one terminal box is required in the central control room.
The terminal box can be divided into 8 ports, 12 ports and 24 ports in terms of its volume.
3, flange flange is also a connector, usually the optical transceiver has an optical interface, which is the flange, which is a connector to connect the optical jumper and optical transceiver. From the perspective of its specifications, it can be divided into FC, ST, SC three.
Required debugging and testing equipment in optical fiber transmission system:
1. Optical fusion splicer It is mainly through the electrode, in the case of an instantaneous discharge, the optical fiber and the optical jumper are welded together, in the welding, it should pay attention to the end face of the optical fiber to be neatly cut, and keep the end face clean.
2, OTDR optical time domain reflectometer This is a detection instrument, it is mainly detected in the optical fiber transmission, whether there is fiber breakage.
3, the optical power meter literally, it is a power measuring instrument, but it does not measure the voltage power, but the power of the optical fiber transmission, and the attenuation of light in the transmission process.
Monitoring the application of optical transceivers:
With the increasing security requirements of the society, surveillance optical transceivers have been widely used in intelligent communities, factories and mines monitoring, urban security, banking networks, road traffic bayonet, electronic police and highway tolls and other industries in the monitoring system . It guarantees the real-time and security of the transmission, and has a large transmission capacity. It not only transmits video, but also transmits audio, data, telephone and Ethernet at the same time, which is respected by people.
1) Analogue optical transceiver The analog optical transceiver adopts PFM modulation technology to transmit image signals in real time, and is currently used more often. The transmit end first performs the PFM modulation on the analog video signal, and then performs the electro-optical conversion. After the optical signal is transmitted to the receiving end, the optical-electrical conversion is performed, and then the PFM demodulation is performed to recover the video signal. Due to the adoption of PFM modulation technology, the transmission distance can easily reach around 30 Km, and the transmission distance of some products can reach 80 Km or even hundreds of kilometers. Moreover, the image signal has little distortion after transmission, and has a high signal-to-noise ratio and little nonlinear distortion. By using wavelength division multiplexing technology, it is also possible to realize bi-directional transmission of image and data signals on a single optical fiber to meet the actual needs of the monitoring project. This analog optical transceiver also has some drawbacks:
a) production debugging is more difficult;
b) It is more difficult for a single optical fiber to achieve multi-channel image transmission, and its performance will be degraded. At present, this analog optical transceiver generally can only transmit 4 channels of images on a single optical fiber;
c) Due to the use of analog modulation and demodulation technology, its stability is not high enough. With the increase of the use time or the change of the environment characteristics, the performance of the optical transceiver will also change, which will cause some inconvenience for the use of the project.
2) Digital Optical Multiplexer Since digital technology has obvious advantages in many aspects compared with traditional analog technologies, just as digital technology has replaced analog technology in many fields, the digitalization of optical transceivers is also an inevitable trend. At present, digital image optical transceivers mainly have two technical methods: one is an MPEG II image compression digital optical transceiver, and the other is a non-compressed digital image optical transceiver. Image compression digital optical transceivers generally use MPEG II image compression technology, which can compress moving images into N×2 Mbps data streams and transmit them over standard telecommunications interfaces or directly over optical fibers. Due to the use of image compression technology, it can greatly reduce the signal transmission bandwidth.
The question of how to select the right video optical transceiver for the selection of video optical transceivers is in front of everyone. Here, we would like to share our years of industry experience with readers who are interested in the selection of video optical transceivers. Optics purchase considerations Analog signals; digital signals < From the signals sent to the optical fiber, optical transceivers can be divided into analog optical transceivers based on analog technology and analog optical transceivers based on digital technology. The working principle of analog optical transceiver is nothing more than modulation, demodulation, filtering and signal mixing. Regardless of whether it is an LED or an LD, its photoelectric modulation characteristics are not linear. Inevitably, problems such as distortion and interference are inevitable in the signal transmission process, and there are insurmountable technologies in terms of large-capacity transmission and multi-service mixed transmission. difficulty.
With the development of the times and the increasing requirements of users for security precautions, surveillance optical transceivers have been more and more widely used in the field of security, and the technology for monitoring optical transceivers has become more and more mature, so the current monitoring optical transceivers can already be realized in one core. Multiple signals such as video, audio, data, telephone, Ethernet, and alarm are transmitted on the optical fiber.
Monitor the optical transmission medium and its characteristics:
The medium used to monitor the optical transceiver is optical fiber. So why choose to transmit it through optical fiber? The main component of the optical fiber is silicon dioxide (SiO2), which accounts for a large proportion of the minerals in the entire earth and can usually be extracted from stones and sand. Fibers made of silicon dioxide (SiO2) are brittle as glass and fine as hair. From its internal composition, optical fibers are classified into single-mode fibers and multi-mode fibers. The core diameter of single-mode fibers is 9 μm, and the core diameter of multi-mode fibers can be divided into 50 μm and 62.5 μm. Because of the composition of the optical fiber, it has the characteristics of long transmission distance, non-conductivity, strong anti-interference ability and good confidentiality. In the long-distance transmission, it is usually the first choice of the majority of engineering companies.
Other attachments:
1. The optical jumper is mainly used for connection. It connects the optical transceiver and the optical fiber. Then, from the perspective of the connectors at both ends of the optical jumper, the optical jumpers are divided into FC jumpers, ST jumpers, and SC jumpers; from the perspective of the optical jumpers, they can be divided into 3m jumpers, 5m Jumpers, 10m jumpers, etc.
2. The terminal box The terminal box, also known as the welding box, is mainly to protect the fusion joint between the optical jumper and the optical fiber. The optical fiber and the jumper are welded into the terminal box through the optical fiber fusion splicer. In general, one terminal box is required for each optical transmitter in the front end, and only one terminal box is required in the central control room.
The terminal box can be divided into 8 ports, 12 ports and 24 ports in terms of its volume.
3, flange flange is also a connector, usually the optical transceiver has an optical interface, which is the flange, which is a connector to connect the optical jumper and optical transceiver. From the perspective of its specifications, it can be divided into FC, ST, SC three.
Required debugging and testing equipment in optical fiber transmission system:
1. Optical fusion splicer It is mainly through the electrode, in the case of an instantaneous discharge, the optical fiber and the optical jumper are welded together, in the welding, it should pay attention to the end face of the optical fiber to be neatly cut, and keep the end face clean.
2, OTDR optical time domain reflectometer This is a detection instrument, it is mainly detected in the optical fiber transmission, whether there is fiber breakage.
3, the optical power meter literally, it is a power measuring instrument, but it does not measure the voltage power, but the power of the optical fiber transmission, and the attenuation of light in the transmission process.
Monitoring the application of optical transceivers:
With the increasing security requirements of the society, surveillance optical transceivers have been widely used in intelligent communities, factories and mines monitoring, urban security, banking networks, road traffic bayonet, electronic police and highway tolls and other industries in the monitoring system . It guarantees the real-time and security of the transmission, and has a large transmission capacity. It not only transmits video, but also transmits audio, data, telephone and Ethernet at the same time, which is respected by people.