| 摘要 |
The invention relates to a method for the transmission of information by means of an optical data transmission line, the ends of which are embodied as an optoelectronic interface, whereby a light source which can be modulated, such as for example a laser, is provided on the transmission side and a light sensitive receiver element is provided on the receiving side, such as for example a photodiode. The signal varying with the received light intensity at the output from the receiving element is amplified and processed. The light received by the receiver element is recorded as such, independent of the current strength of he modulated signal and displayed at a signal monitoring output to show the presence or otherwise of a data signal. The invention further relates to a corresponding device. According to the invention, the emitted light on the transmission side may be reduced so far below the minimum modulation level such that on the receiver side the threshold value for the display of a received signal by the signal monitoring device is dropped below and thus the output of the signal monitoring device has an error signal and then the emitted light is restored above the said threshold level such that the signal monitoring device shows the presence of an optical signal. Said reduction and resumption of the light energy occurs in a cycling coded form and the output signal from the signal monitoring device is used as receiver side data output and correspondingly analysed, whereby the light emitted on the transmission side is reduced so far below the minimum threshold value of the signal amplitude used for data transmission that the signal monitoring output on the receiver side end, registers and displays an error input signal for the light receiving element. The emitted light is then again restored to above the threshold, whereby the reduction and restoration of the light energy occur in a relatively slow time cycle in coded form and the corresponding coded signal from the signal monitoring output is evaluated by a corresponding analytical logic.
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