| 摘要 |
<p>The disclosure describes a synchronous type optical modulation-demodulation system of the type which transmits data by means of optical fibers. It is characterized by a transmitting circuit comprising a leading and falling edge detection circuit to generate pulses in response to the leading or the falling of a timing pulse, a means to convert the output signal value fed from the leading and falling edge detection circuit into positive or negative pulses in response to the level of the electric input signal data, a driving circuit for a light emitting element for inputting a signal at a predetermined level in response to a ready-for-sending signal and positive or negative polarity from the converting means, a light emitting element which is charged by the light emitting element driving circuit and intensitymodulated by said input signal, and an optical coupling means to guide the output light from said light emitting element into said optical fibers. The system also has a receiving circuit comprising an optical coupling means to optically combine the optical fibers and a light receiving element, the light receiving element converting light signals which are transmitted through the optical fibers into electric signals, a gain variable amplifying circuit to amplify the electric signal from the light receiving element to a predetermined level, an averaging circuit to average the output from the gain variable amplifying circuit, a binary circuit to compare the averaged output from the averaging circuit with the polarity of the output pulse from the gain variable amplifying circuit and to output binary signals in response to the positive or the negative polarity thereof, a flip-flop circuit to input the output from the binary circuit at the set or the reset terminals thereof respectively and output receiving data signal, and a flip-flop circuit to input the output from the binary circuit and an output receiving timing pulse.</p> |
