TRANSMISSION SYSTEM FOR ANALOG OPTICAL SIGNAL

摘要

PURPOSE:To secure the accurate calibration for the optical transmission system by supplying the different and fixed calibration current to the transmission light emitting elements in sequence. CONSTITUTION:The measurement current sent from analog value measuring system 1 at the remote place is supplied to light emitting element 3 via switch 2. The optical signal passed through optical transmission line 6 is converted into the electric signal through photo detector 8 and then supplied to process circuit 10. Circuit 10 memorizes the accurate signal level and thus gives the calibration indication signal to light emitting element 9. Based on this calibration indication signal, the transmission side generates the calibration current to supply it to element 3. The calibration is performed in sequence and automatically at plural points, and thus the accurate calibration is secured althrough some fluctuation may occur to the transmission system due to the temperature change or the like. The increment of the transmission lines is enough with just one piece for the calibration indication signal, and furthermore this transmission line can be omitted if the two-way optical fiber is used and thus to enhance the economical property.