| 摘要 |
PURPOSE:To attain optimum AGC(automatic gain control) automatically even in the case of long or short range transmission by providing an equalization amplifier means, a gain control amplifier means and a control means. CONSTITUTION:In the case of long distance optical transmission, gain control amplifier means 221, 222 control the gain of a photoelectric conversion means 201, 202 and an equalization amplifier means 21 with a control voltage in response to an output level of the equalization amplifier means 21 to form 2 system of AGC loops. On the other hand, in the case of short distance optical transmission, a control means 23 inactivate the means 202 in the means 201, 202 to activate only one system in the 2 system of AGC loops. Thus, in the case of short distance optical transmission, the AGC loop of one system only is formed automatically and optimum AGC is applied to the system without deviation of AGC dynamic range. Thus, optimum AGC is applied automatically even in any of the long or short range transmission. |
