| 摘要 |
PURPOSE:To make unnecessary a clock extracting circuit by reproducing the clock signal needed for coding from the transmitted reception data and to improve the quality of transmission data by selecting the transmission/reception speed in response to the operation speed between terminal devices. CONSTITUTION:Data terminal devices 1 and 2 are connected to each other with an optical transmission line 19 via optical data MODEMs 10 and 20. Thus an optical data transmission system is obtained. The data signals undergo the multi- point sampling through multi-point sampling circuits 11 and 21 of MODEMs 10 and 20 respectively. Then changing point detecting circuits 12 and 22 detect the changing point of the clock signal produced by data. The clocks given from clock generators 14 and 24 are applied to code converting circuits 13 and 23. Then thse clocks are superposed on each other after deciding that they departed from the code rules of the data signal, and the output is transmitted to the line 19 in the form of optical signals from electricity-light converting circuits 15 and 25. Then code adversely converting circuits 27 and 17 of the reception sides of MODEMs 10 and 20 respectively deliver data signals D2. The clock signals CLK2 are delivered from clock reproducing circuits 18 and 28, and the transmission/reception speed is set at the operation speed between devices 1 and 2. |
