| 摘要 |
PROBLEM TO BE SOLVED: To require only a narrow light reception dynamic range, to prevent a high speed operation from being requested to the level follow-up ability of a burst signal, to simplify a circuit and to improve ability since the reception levels of a master station side are adjusted almost equal by automatically setting a transmission level in accordance with the distance on a slave station side. SOLUTION: The burst signal from the master station 2 is continuously transmitted to the respective slave stations 1. The respective slave stations 1 receive the burst signals and compare the signal levels with the reference voltage of a comparator. Reference voltage is set to zero voltage with the reception level of the slave station 1b in an intermediate distance as a standard. The slave station 1a in the remote distance outputs voltage in a minus direction and the slave station 1c in the near distance outputs voltage in a plus direction in accordance with the respective distances. A level control circuit converts a signal into a level control signal for setting the transmission level corresponding to the distances based on the output voltage of the comparator. Namely, the slave station 1b is set to the standard transmission level, the slave station 1a to the transmission level obtained by raising the difference of the reception level and the slave station 1c to the transmission level lowered by the difference of the reception level. |
