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Optical transceiver is the terminal equipment for optical signal transmission; the optical transmission system consists of three parts: light source, transmission medium and detector. According to the transmission signal, it can be divided into digital transmission system and analog transmission system. Therefore, the video optical transceiver is to convert 1 Equipment that converts multiple analog video signals into optical signals through various encodings and transmits them through optical fiber media is divided into analog optical transceivers and digital optical transceivers.
The operating environment of this tutorial: Windows 10 system, DELL G3 computer.
An optical transceiver is a terminal device for optical signal transmission.
Due to the improvement of technology and the reduction of optical fiber prices, it has been well applied in various fields (mainly reflected in security monitoring). Therefore, various optical transceiver manufacturers have sprung up like mushrooms after a rain. However, most of the technologies of the manufacturers here are not fully mature, and developing new technologies requires money, manpower, and material resources. Most of these manufacturers are small and medium-sized enterprises, and various brands have appeared one after another. However, the quality is still similar. Foreign optical transceivers are good but expensive. Therefore, domestic manufacturers have transformed the production of optical transceivers to meet domestic needs.
The optical transmission system consists of three parts: light source (optical transmitter), transmission medium, and detector (optical receiver).
According to the transmission signal, it can be divided into digital transmission system and analog transmission system.
In an analog transmission system, the input signal is changed into a continuous change in the amplitude (frequency or phase) of the transmission signal. The analog transmission system of optical fiber performs analog modulation of light intensity, and the modulation power of the light source changes with the amplitude of the modulation signal. However, due to the serious nonlinearity of the light source, its signal-to-noise ratio, transmission distance and transmission frequency are very limited.
Analog optical transceiver
The analog optical transceiver uses PFM modulation technology to transmit image signals in real time. The transmitting end first performs PFM modulation on the analog video signal, and then performs electro-optical conversion. After the optical signal is transmitted to the receiving end, it performs optical-to-electrical conversion, and then performs PFM demodulation to recover the video signal. Due to the use of PFM modulation technology, its transmission distance can reach 50Km or further. By using wavelength division multiplexing technology, two-way transmission of images and data signals can also be realized on one optical fiber to meet the actual needs of monitoring projects. This kind of analog optical transceiver also has some shortcomings:
a) It is difficult to produce and debug;
b) It is difficult to realize multiple image transmissions with a single optical fiber, and the performance will decrease. This kind of analog optical transceiver Generally, only 4 channels of images can be transmitted on a single optical fiber;
c) The anti-interference ability is poor, it is greatly affected by environmental factors, and there is temperature drift;
d) Due to the It is an analog modulation and demodulation technology, and its stability is not high enough. As the use time increases or the environmental characteristics change, the performance of the optical transceiver will also change, which will bring some inconvenience to the engineering use.
digital optical terminal
Since digital technology has obvious advantages in many aspects compared with traditional analog technology, just as digital technology has replaced analog technology in many fields Similarly, the digitization of optical transceivers is also an inevitable trend. There are two main technical methods for digital video optical transceivers: one is MPEG II image compression digital optical transceiver, and the other is all-digital non-compressed video optical transceiver.
Image compression digital optical transceivers generally use MPEG II image compression technology, which can compress moving images into N×2Mbps data streams for transmission through standard telecommunications communication interfaces or directly through optical fiber. Due to the use of image compression technology, it can greatly reduce the signal transmission bandwidth.
The all-digital non-compressed video optical transceiver adopts all-digital uncompressed technology, so it can support the distortion-free transmission of any high-resolution motion and still images; it overcomes the simultaneous multi-channel signals of conventional analog frequency modulation, phase modulation, and amplitude modulation optical transceivers. Disadvantages include serious intermodulation interference during transmission, being easily affected by environmental interference, poor transmission quality, and low long-term working stability. It also supports the parallel transmission of bidirectional audio, bidirectional data, bidirectional switch, Ethernet, telephone and other signals. It is convenient for on-site wiring and is plug-and-play. Compared with traditional analog optical transceivers, digital optical transceivers have obvious advantages:
1) Longer transmission distance: up to 80Km or even further (120Km);
2) Supports lossless video Regeneration relay, so multi-level transmission mode can be used;
3) Less environmental interference, high transmission quality;
4) Supported signal capacity up to 16 channels, or even more (Road 32, Route 64, Route 128).
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