Optical signal transmission requirements
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The signal types used in process control in the process industry are pneumatic signals, electric signals and optical signals. This article is a companion article to "Transmission Requirements for Electric Signals in Instrument Signal Transmission" and focuses on introducing knowledge related to optical signal transmission. 1. Optical signal transmission requirements The future development direction of the automation field is control decentralization, information integration, networking, openness and multimedia applications. Therefore, there is an increasing need for high-speed, large-capacity, multiplexed and high-reliability signal transmission. The use of light as a means of transmission has rapidly expanded into fiber optic communication systems due to the development of low-loss optical fibers, as well as optical devices such as light-emitting diodes and semiconductor lasers. Changhui Instruments yunrun.com.cn Optical fiber communication system has the following characteristics: ①Low loss (small attenuation). Without using repeaters, the transmission distance can reach 10km. ②Wide bandwidth. High-speed, multi-channel transmission can be carried out in the band from 100MHz to several GHz. ③Non-inductive insulator. Since high-voltage electromagnetic waves will not cause electromagnetic induction, it will not be affected by electromagnetic interference and lightning interference, and can be used in ground potential changes or explosive environments. ④Small diameter, light weight and long life. Compared with coaxial cables, the cross-sectional area and mass ratio are approximately less than 1/10. ⑤The texture is brittle and the mechanical strength is poor. ⑥Fiber splicing and cutting require specialized tools and techniques. See Table 1 for a comparison of transmission media. Table 1 Comparison of transmission media The composition of the optical fiber communication system is shown in the figure below:
Sorry, I can't display the image. However, the basic components of an optical fiber communication system include a light source, an optical fiber transmission medium, a receiver and a signal processing device. The requirements for optical signal transmission include the following aspects:: 1. Speed and bandwidth: Optical fiber communication systems can achieve high-speed data transmission, and their bandwidth can range from 100MHz to several GHz. Therefore, optical signal transmission requires high speed and bandwidth capabilities. 2. Transmission distance: The transmission distance of optical fiber communication systems can reach tens of kilometers or even further, and signal loss can still be maintained low without repeaters. Therefore, optical signal transmission requires long-distance transmission. 3. Signal reliability: Fiber optic communication systems are resistant to electromagnetic interference and lightning interference because optical fibers, as insulators, are not affected by electromagnetic induction. Optical signal transmission requires good anti-interference properties to ensure signal reliability and stability. 4. Security: Optical signal transmission is carried out through optical fiber transmission media, so the optical signal will not leak out during the transmission process and has high security. 5. Compatibility: Optical signal transmission requires compatibility with other types of signals, such as electrical signals or other communication protocols. To sum up, optical signal transmission requires features such as high speed, large capacity, multiplexing, high reliability, long-distance transmission and compatibility with other signals. .