Design & Implementation Of Optical Fiber Transmittion System Used For Monitoring & Controlling Traffic

This task comes from the plan of Harbin Rock Opto-electronic TechniqueCo.,LTD-the digital optical transmitter and receiver used in industry andtraffic ,which has been studied in order to conquer the disadvantages of analog device .It must accurately transmit one video signal and reversely transmit one data signal in one fiber and work well when the temperate has changed greatly.Although the special system of optical communication has already used widely ,its communication mode mainly depends on analog communication. The most disadvantage is that the damnification of image quality is accumulated and it will cause the distortion of video signal .When the video analog signal has been changed into digital signal ,it will not only conquer the problem that analog signal communication posses ,but also bring many new characters. There exist random long successive "0" or "1" in the code of image signal, which are not fit for the transmit of the optical channel. This paper makes a brief discussion on its reason and also gives out a practical method to solve the problem .When the temperate has changed greatly .The system will also transmit one reversal data signal in order to control the vidicon on site .Because the date rate is very low and can not fit for transmitter in optical channel ,it is necessary to modulate the signal.The system makes use of the WDM mode to realize two reverse signals transmitter in one fiber and designs the practical circuit .At last ,the paper gives out the accurate capabilities that are attributed to the video signal and the data signal. The experiment proves that this method is both right and practical.