| 摘要 |
PURPOSE:To eliminate a circuit of a high-speed receiving AGC function from a main station and to enable immediately a reproduction of data, by controlling the transmitting level of a substation in response to the level of the signal received at the substation. CONSTITUTION:A main station is connected to plural substations via descending and ascending lines to form a data transmitting system. A level detecting circuit 9 is provided at the output side of a waveform shaping circuit 8 of a receiver at the substation of the above-mentioned transmitting system. The circuit 9 detects the photodetecting level of the signal supplied from the transmitting side. Then an AGC control voltage is generated in response to the photodetecting level detected by the circuit 9 and then applied to a variable amplifying circuit 7 as well as to a variable light transmitting circuit 16. Then the transmitting level to the main station is controlled in response to the photodetecting level. As a result, a reproduction of data is immediately possible without adding a circuit containing a high-speed AGC function to the main station. |
