Light signal remote control apparatus and light signal level controlling method

A light signal level controlling method for a light signal remote control apparatus which includes a light transmission section including a light source for emitting light to be transmitted, and a light reception section located in a spaced relationship from said light transmission section and including a first light detection section for receiving the light signal from said light source of said light transmission section via an optical fiber, comprising the steps of:

• producing, in response to light detection information detected by said first light detection section of said light reception section, a first light control signal for controlling a state of the light signal from said light source;
• producing, in said light transmission section, in response to a light emitting state of said light source, a second light control signal for controlling the state of the light signal from said light source;
• and
• selectively outputting to said light source one of the first light control signal and the second light control signal with which the light signal from said light source is controlled lower than that with the other.

A light signal transmission apparatus, comprising:

• a supervisory signal light production apparatus including a supervisory signal light source for producing supervisory signal light;
• a transmission apparatus connected to said supervisory signal light production apparatus via an optical fiber for multiplexing signal light as a main signal with the supervisory signal light transmitted thereto from said supervisory signal light source via said optical fiber and transmitting the multiplexed signal light;
• a light branching section for branching the supervisory signal light transmitted thereto via said optical fiber;
• a first level detection section for detecting a level of part of the light signal branched by said light branching section;
• a first level control signal outputting section for outputting, in response to detection information from said first level detection section, a control signal for controlling a level of the supervisory signal light to be produced by said supervisory signal light source;
• a second level detection section for receiving backward light of the supervisory signal light produced by said supervisory signal light production apparatus and detecting a level of the backward light;
• a second level control signal outputting section for outputting, in response to detection information from said second level detection section, a control signal for controlling the level of the supervisory signal light to be produced by said supervisory signal light source so as to become higher than the level of the supervisory signal light to be controlled by the control signal from said first level control signal outputting section;
• a switch section for selecting one of the control signal from said first level control signal outputting section and the control signal from said second level control signal outputting section with which the level of the supervisory signal light is controlled lower than that with the other;
• and
• a supervisory signal light control section for controlling said supervisory signal light source in response to control information from said switch section so that the supervisory signal light to be produced by said supervisory signal light source has a fixed level.

A supervisory signal light level controlling method for a light signal transmission apparatus which includes a supervisory signal light production apparatus including a supervisory signal light source for producing supervisory signal light, and a transmission apparatus connected to said supervisory signal light production apparatus via an optical fiber for multiplexing signal light as a main signal with the supervisory signal light transmitted thereto from said supervisory signal light source via said optical fiber and transmitting the multiplexed signal light via said optical fiber, comprising the steps of:

• detecting a level of the supervisory signal light transmitted via said optical fiber and producing, in response to the detected level, a first control signal for controlling a level of the supervisory signal light;
• detecting a level of backward light of the supervisory signal light produced by said supervisory signal light production apparatus and producing, in response to the detected level, a second control signal for controlling a level of the supervisory signal light;
• and
• controlling the level of the supervisory signal light to be produced by said supervisory signal light source using the first control signal when the level of the supervisory signal light controlled is lower than a value set in advance, but controlling the level of the supervisory signal light to be produced by said supervisory signal light source using the second control signal when the level of the supervisory signal light is higher than the value set in advance.