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一、绪言光纤通信方式从光纤的宽频带特性可以看到对于解决图象传输系统的经济性是很有前途的。虽然图象传输也有各种应用领域,但在比较短的距离,束数少,多重性也小的时候,工程费用是个关键;而纤维价格相当便宜,与以往的金属线系统比较是非常经济的。并且由于纤维的损耗小,可以5～10km不加中继,更可说是一个很大的优点。光纤的优点是频带宽和损耗低。PCM、FM和PPM方式可以说就是利用宽频带特性的传输方式。不过,光纤的损耗虽有逐年下降的趋势,然而多模光纤在用于宽带信号传输时,由于带宽的限制而限制了中继间隔。另一方面,在用发光二极管(LED)进行基带直接调制时,由于LED与纤维的耦合效
I. INTRODUCTION Optical Fiber Communication From the broadband characteristics of optical fiber, it can be seen that it is promising for solving the economic problem of image transmission system. Although there are a variety of applications for image transmission, engineering costs are key when the distances are relatively short, the number of bundles is small and the multiplicity is small. The cost of fiber is relatively cheap and very economical compared with conventional wire systems . And because of the small fiber loss, you can 5 ~ 10km without relay, it can be said is a great advantage. The advantages of optical fiber are low bandwidth and low loss. PCM, FM and PPM can be said that the use of broadband features of the transmission. However, although the loss of optical fibers tends to decrease year by year, multimode optical fibers limit the relay interval due to the limitation of bandwidth when used for broadband signal transmission. On the other hand, in the direct modulation of the baseband with a light-emitting diode (LED), due to the coupling effect between the LED and the fiber