| 摘要 |
PURPOSE:To reduce the deterioration of the information quantity caused by various types of electromagnetic noise, by using the signal transmission line connecting among the antenna, the front end part and the transmitting/receiving part each for the optical fiber transmission line. CONSTITUTION:The electric wave signal supplied from antenna 1 is converted into the intermediate frequency signal at frequency converting amplifier 12 after passing through transmission/reception isolating circuit 11. And the current proportional to the signal voltage is supplied to LED14 by LED driving circuit 13. Then the current signal is converted into the light intensity signal through LED14 and then transmitted to one piece of optical fiber line 15 among optical fiber transmission lines 7. The optical fiber is made of the glass or the transparent synthetic resin and thus an nonelectric conductor. Thus the various types of electric noise sent from the engine part or the like in the main body of an automobile or the electromagnetic noise given from outside is never induced to the optical fiber. As a result, a perfect countermeasure is ensured to the noise by applying the local electromagnetic shielding of the signal frequency band including the power supply to front end 2a and transmitter/receiver 3a each. |
