| 摘要 |
PURPOSE:To make unnecessary the high parts accuracy of a resistance element and to make easy an adjustment by connecting serially three resistances or above, providing divided voltage circuit, generating a reference voltage and comparing a level, at a receiver for an optical pulse signal. CONSTITUTION:An optical pulse train sent from a transmitting side through an optical fiber is detected, amplified 9 and inputted through a capacitor 13 to a comparing circuit 10 by a photodetecting element 8. Resistances 21-24 are connected between an electric power source voltage terminal 17 and an earth, and inputted to comparing devices 10 and 12 with the divided voltage of respective connecting points E, F and G as the reference voltage. When the value superposing the output of the capacitor 13 through a resistance 20 with the divided voltage value of an F point and inputted to the comparing circuit 10, exceeds the voltage of an E point, the pulse is outputted, the pulse is continuously extended by an integrator 11, and inputted to a comparing circuit 12. While the value exceeds the voltage of a G point, a comparing device 12 outputs 18 the flat level signal. Thus, the high part accuracy of the resistance element for forming the reference voltage is made unnecessary, and the adjustment is made easy. |
