| 摘要 |
PURPOSE:To reduce a reference wave component in a pulsed FM signal and to improve the influence of band restriction by dividing the frequency of a rectangular wave output obtained from a pulsed FM modulator as it is by a frequency divider and transmitting the frequency-divided signal through an optical fiber. CONSTITUTION:A video signal from a video input terminal 1 is converted into a pulsed FM Signal or PFM (pulse frequency modulation) signal by a pulse modulator 11, the frequency of the converted signal is divided into 1/2 by the frequency divider 12 and the divided signal is converted into an optical signal by an optical transmitter 13 and sent to the optical fiber 14. At that time, the duty ratio of a pulse outputted from the frequency divider 12 is completely turned to 50% and no low frequency component is included. On the other hand, the optical signal received by a photodetector 15 is converted into an electric signal and then converted into a PFM signal by a PFM converter 16. Since the PFM signal includes the video signal which is a wave to be modulated, the video signal is removed by a low pass filter 19.
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