| 摘要 |
PURPOSE:To eliminate the need for expensive electrooptic and photoelectric converter for high speed response by applying FM modulation with a carrier having a different frequency to an audio and a voice signal respectively, applying modulation to a digital signal with a carrier having a different frequency from those of the two signals and converting the rectangular signal into the optical signal. CONSTITUTION:A video signal V, an audio signal A are subject to FM modulation by carrier frequencies fV, fA of FM modulators 1, 2 and the FM modulation index for the signal V is selected to be nearly 0.5. A carrier frequency fD generated by a digital data modulator 3 is used for the digital signal D for modulation and the signals are synthesized, the amplitude is limited by a limiter 5 to be a rectangular signal, it is converted into an optical signal by using an electrooptic converter 6 and sent to the reception side through an optical transmission line 7. The receiver side uses an photoelectric converter 8 to convert the signal into an electric signal, it is demultiplexed into signals by a demultiplexer 9 and demodulated into original signals V, A, D through FM demodulators 10, 11 and a digital demodulator 12. |
