Light communication system

Abstract

Abstract PURPOSE:To make it possible to exercise stable gain control over a receiver even when the transmission of fluctuations of the mark rate of data is innterrupted, by multiplexing light signals with constant mean values, by light emission wavelength different than a light output transmitting the data. CONSTITUTION:Data to be transmitted are applied to driving circuit 1, which provides the intensity modulation of light emitting element 2. Light emitting element 3, on the other hand, output a photosignal of a constant mean value. The light outputs of elements 2 and 3 are mixed by light mixer 7, the output of which is sent to optical fiber 8. The light is separated by light branching filter 9 into components of wavelengths of elements 2 and 3 and the light output of element 2 is detected by photodetector 10 and applied to main amplifier 12. The light output of element 3, on the other hand, is detected by photodetector 13 and applied to gain controller 14 to control the gain of amplifier 12. Therefore, the light reception signal of constant amplitude is inputted to discriminator 15 without reference to the magnitude of the transmitted light and the data are reproduced by an adequate threshold level. To interrupt the data transmission, element 3 is only left in operation, exercising control over the gain of the receiver.

Inventors

• 👤 Masayuki Takami
• 👤 Takao Ito
• 👤 Toshifumi Tamura
• 👤 Masaru Nakamura

Bibliographic Details