Digital optical fiber communication system
Optical fiber transmission system is an ideal channel for digital communication. Compared with analog communication, digital communication has many advantages, such as high sensitivity and good transmission quality. Therefore, most large-capacity and long-distance optical fiber communication systems adopt digital transmission methods.
In the optical fiber communication system, the binary light pulse "0" code and "1" code are transmitted in the optical fiber, which is generated by the on-off modulation of the light source by the binary digital signal. The digital signal is generated by sampling, quantizing and encoding the continuously changing analog signal, which is called PCM (pulse code modulation), that is, pulse code modulation. This kind of electrical digital signal is called a digital baseband signal, which is generated by a PCM electrical terminal.