| 摘要 |
PURPOSE:To shorten the transmission band by combining the optical signals sent from the digital information source and the analog signal source via the optical coupler to send the combined signal to one piece of fiber and then transmitting the analog signal featuring a small amount of the leak along with the digital signal with a simple circuit. CONSTITUTION:Code converter 2 converts the digital signal sent from digital information source 1 in to such code as to feature the combination of the binary code pulses to give a fixed DC level to the digital optical signal. And the low frequency component contained in the transmitted digital optical modulation signal is removed through low band cut-of filter 3. Then the signals which are arranged to from the low frequency component region with elimination of the analog signal component are delivered from analog signal source 8. The optical signals from information source 1 and signal source 8 are combined via optical coupler 7 to be sent out to a piece of optical fiber. Thus the analog signal featuring a small amount of the leak noise is transmitted along with the digital signal through a simple circuit, shortening the necessary transmission band for the optical fiber. |
