| 摘要 |
PURPOSE: To collect plural information in remote places with a simple constitution by one optical fiber by modulating plural signal sources, which are superposed one over another and are transmitted, by specific frequency bands respectively. CONSTITUTION: With respect to signals 201 and 209, 187.5MHz and 262.5MHz carriers sent from carrier generators 203 and 210 are modulated in a 27MHz band width in modulators 202 and 211 respectively, and they are amplified by amplifiers 203 and 212, and DC voltages from power sources 206 and 214 are superposed by bias circuits 205 and 213. The modulated signal of the signal 201 is inputted to a semiconductor laser light source LD207 and is optically modulated and is inputted to an external optical modulator 215 through an optical transmission line 208, and the modulated wave of the signal 209 is directly inputted to the external modulator 215 from the bias circuit 213. Unnecessary signal components of the difference and the sum of frequency components of both signals can be easily removed after photoelectric conversion in a receiver because they are not superposed on signal components of a required frequency band, and thus, plural information are collected by one optical fiber. |
