JPH0821900B2 - Optical repeater monitoring system - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical repeater monitoring system, and more particularly to an optical repeater monitoring system using remote loopback.

[0002]

2. Description of the Related Art An example of a conventional optical repeater will be described with reference to FIG. As shown in FIG. 2, the conventional optical repeater includes a control signal detection circuit 33 for detecting a first control signal sent from a monitoring station via an optical fiber transmission line, and a second control signal detecting circuit 33 sent from the monitoring station. A control signal detection circuit 36 for detecting the control signal of
A voltage-frequency conversion circuit 31 for converting a DC voltage representing the state of the light source 27 into a corresponding frequency, and a part of the output light of the light source 27 is input to the optical repeater in the opposite direction by the output signal of the control signal detection circuit 33. An optical switch 39 for switching back, a gate circuit 37 opened by the output signal of the control signal detection circuit 36 and passing the output signal of the voltage-frequency conversion circuit 31, and a transmission signal of the repeater by the output signal of this gate circuit 37. And a mark rate modulation circuit 38 for modulating the mark rate of the output light, and a part of the output light is returned by the first control signal, and the transmission signal of the repeater is changed by the output signal of the voltage-frequency conversion circuit 31 by the second control signal. It is configured to return a part of the modulated output light.

In FIG. 2, 21a and 21b are optical fiber cables, and 22a and 22b are optical fibers.
Then, when a control signal is sent from the monitoring station, the sent signal is reproduced through the optical / electrical conversion circuit 23a, the equalization amplification circuit 24, and the identification reproduction circuit 25, and the light source 27 such as a semiconductor laser is generated through the light source drive circuit 26. To drive. On the other hand, the frequency component of the output signal of the identification reproduction circuit 25 assigned to this repeater is given to the control signal detection circuit 33 via the bandpass filter 34. Here, this control signal detection circuit 33
Is, for example, a flip-flop circuit which is set when receiving this control signal, and drives the optical switch 39 for folding by the output signal to output a part of the output light of the light source 27 to the input of the repeater in the opposite direction. It is connected to the optical / electrical conversion circuit 27b and returned to the monitoring station.

Next, when the second control signal different from the first control signal is transmitted from the monitoring station, the control signal detection circuit 36 is set via the bandpass filter 35. On the other hand, the voltage drop of the resistor 30 due to the output current of the DC amplification circuit 29 for adjusting the bias current according to the light output of the light source 27 is converted into a frequency corresponding to the voltage drop by the voltage / frequency conversion circuit 31, The pulse generation circuit 32 generates a pulse signal of that frequency. Reference numeral 28 is a photodiode that receives an optical signal from the light source 27. And
When the control signal detection circuit 36 is set, the gate 37 is opened, and the output signal of the pulse generation circuit 32 is given to the mark ratio modulation circuit 38 to modulate the output signal of the identification reproduction circuit 25 by the mark ratio to perform the light source drive circuit 26. Give to. The reception input signal detection circuit 40 has a sufficiently large time constant so that the control signal detection circuits 33 and 36 are not reset due to a signal switching time or a momentary interruption. An optical interrupter having such a structure is disclosed in, for example, Japanese Patent Application Laid-Open No. 57-118448.

[0005]

However, this conventional optical interrupter has a problem in that it cannot be monitored online because the data transmission signal is folded back during monitoring. The present invention has been made to solve such a problem, and an object thereof is to obtain an optical repeater monitoring system capable of online monitoring.

[0006]

SUMMARY OF THE INVENTION An optical repeater monitoring system of the present invention provides an optical signal obtained by multiplexing an optical signal of wavelength λ ₁ for data transmission, which is sent from a monitoring station via an optical fiber transmission line. A first optical multiplexer / demultiplexer for separating from the inside; a first optical / electrical conversion circuit for performing optical / electrical conversion of an optical signal of wavelength λ ₁ separated by the first optical multiplexer / demultiplexer; first electric / and an optical conversion circuit, folded controlling the wavelength lambda ₂ of the light transmitted from the monitoring station to convert the electrical signal converted by the first optical / electrical conversion circuit again to the wavelength lambda ₁ of the optical signal A second optical / electrical conversion circuit for performing optical / electrical conversion of the optical signal having the wavelength λ ₂ after being separated by the first optical multiplexer / demultiplexer from the multiplexed optical signal; Frequency component assigned to each repeater from the signal converted electrically by the optical / electrical conversion circuit A band pass filter for extracting a first makes a determination of the control state from the output of the band pass filter, second and third control signal detection circuit which sends a control signal to the optical switch, the wavelength lambda ₂ of light A second electrical / optical conversion of the signal into two optical signals of wavelength λ ₂ and wavelength λ ₃
And a third electro-optical conversion circuit, and the second and third
A first optical switch that selects and outputs any one of the outputs of the electric / optical conversion circuit of the control signal detection circuit, and an output of the first optical switch of the control signal detection circuit. A second optical switch that outputs one of two types of outputs under control, an optical signal output of the wavelength λ ₂ of the second optical switch, and an optical signal of the wavelength λ ₁ are combined. A second optical multiplexer / demultiplexer that outputs the optical signal of the wavelength λ ₃ from the optical fiber transmission line connected to the next stage repeater to the optical fiber transmission line connected to the next stage repeater, The optical signal of wavelength λ ₃ demultiplexed from the second optical multiplexer / demultiplexer and the optical signal of wavelength λ ₃ output from the second optical switch are input and either input is performed by the control of the control signal detection circuit. And outputs the first optical signal connected to the optical fiber transmission line on the monitoring station side. To duplexer in which a third optical switch for transmitting an optical signal of wavelength lambda _3. Also the monitoring station
From the optical fiber via the first optical fiber transmission line
Optical signal of wavelength λ ₁ for data transmission from among the optical signals
And the optical signal of wavelength λ ₂ for loopback control
The optical signal having the wavelength λ ₃ is separated from the first optical fiber.
First optical multiplexer to be transmitted to the transfer sending passage (1), a monitoring station
It is sent via the second optical fiber transmission line on the opposite side.
The optical signal of wavelength λ ₃ is separated and the optical signal of wavelength λ ₁ is
No. ₂ and optical signal of wavelength λ ₂ are combined and second optical fiber transmission is performed.
The second optical multiplexer / demultiplexer (12) for sending to the optical path and the first optical multiplexer / demultiplexer.
From the optical signal of wavelength λ ₂ separated by the demultiplexer, this wavelength λ ₂
Means for generating an optical signal of wavelength λ ₃ in addition to the optical signal of
(4,10,11) and separated by the first optical multiplexer / demultiplexer
The repeater is under test from the optical signals of wavelength λ _2.
Detection means (4, 5, 6) for detecting whether or not
When the test state is detected by the means, it is generated by the generation means.
The optical signal of wavelength λ ₃ is input to the first optical multiplexer / demultiplexer,
When not in the test state, the optical signal of wavelength λ ₂ is input to the second optical
Input to the demultiplexer and separated by the second optical multiplexer / demultiplexer
The input optical signal of wavelength λ ₃ is input to the first optical multiplexer / demultiplexer.
Switch means (7, 8, 9) for switching.

[0007]

In the present invention, the data transmission signal, the control signal, and the monitoring signal are wavelength-multiplexed, passed through the same optical fiber transmission line, and the control signal is folded back during the test.

[0008]

The present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of an optical repeater monitoring system according to the present invention. In FIG. 1, reference numeral 1 is an optical multiplexer / demultiplexer for separating an optical signal having a wavelength λ ₁ for data transmission sent from a monitoring station via an optical fiber transmission path from the multiplexed optical signals. An optical / electrical conversion circuit 3 for performing optical / electrical conversion of the optical signal having the wavelength λ ₁ separated by the optical multiplexer / demultiplexer 1, 3 again converts the electric signal converted by the optical / electrical conversion circuit 2 into light of the wavelength λ ₁ . It is an electric / optical conversion circuit for converting into a signal.

Reference numeral 4 designates the optical / electrical of the optical signal of wavelength λ ₂ after being demultiplexed by the optical multiplexer / demultiplexer 1 from the optical signal of the optical signal of the wavelength λ ₂ for the loopback control transmitted from the monitoring station. An optical / electrical conversion circuit for performing conversion 5 is an optical / electrical conversion circuit 4
A bandpass filter that extracts the frequency components assigned to each repeater from the signal electrically converted by
6 is a control signal detecting circuit for sending the first to third control signals to the optical switch 7-9 performs judgment of the control state from the output of the band-pass filter 5, the optical signal of the wavelength lambda ₂ is 10,11 It is an electrical / optical conversion circuit that performs electrical / optical conversion into two optical signals of wavelength λ ₂ and wavelength λ ₃ .

Reference numeral 7 denotes an optical switch for selecting and outputting either one of the outputs of the electric / optical conversion circuits 10 and 11 under the control of the control signal detecting circuit 6, and 8 denotes the output of the optical switch 7 as a control signal. An optical switch 12 outputs one of two kinds of outputs under the control of the detection circuit 6, and 12 denotes an optical signal output of the optical switch 8 having a wavelength of λ ₂ and an optical signal output from the electrical / optical conversion circuit 3 of λ ₁ . An optical multiplexer / demultiplexer that combines optical signals of wavelengths and outputs them to the optical fiber transmission line connected to the next-stage repeater, and separates the optical signal of wavelength λ ₃ from the optical fiber transmission line connected to the next-stage repeater. It is a wave instrument.

The optical switch 9 is the optical multiplexer / demultiplexer 1.
And outputs one of the input by the control of the inputs the optical signal of the wavelength lambda ₃ outputted from the optical signal and an optical switch 8 of the wavelength lambda ₃ that is separated control signal detection circuit 6 from the second optical fiber transmission monitoring station The optical signal having the wavelength λ ₃ is sent to the optical multiplexer / demultiplexer 1 connected to the optical path.

Next, the operation of the embodiment shown in FIG. 1 will be described. First, from the monitoring station, the optical signals of wavelength λ ₁ and wavelength λ ₂ are wavelength-multiplexed and sent via the optical fiber transmission line. Here, the optical signal of wavelength λ ₁ is used for data transmission, and the optical signal of wavelength λ ₂ is used for folding control.
When the repeater receives the optical signal from the monitoring station, the optical multiplexer / demultiplexer 1
Are separated into optical signals of wavelength λ ₁ and wavelength λ ₂ . The optical signal of the wavelength λ ₁ is converted into an electrical signal by the optical / electrical conversion circuit 2 and then converted again into an optical signal of the wavelength λ _{1 by} the electrical / optical conversion circuit 3 and the other wavelength light by the optical multiplexer / demultiplexer 12. It is multiplexed with the signal and output to the optical fiber transmission line on the next repeater side.

On the other hand, the optical signal of wavelength λ ₂ is converted into an electrical signal by the optical / electrical conversion circuit 4 and then input to the two electrical / optical conversion circuits 10 and 11 and the bandpass filter 5.
One of the two electrical / optical conversion circuits 10 and 11 is converted into an optical signal of wavelength λ _{2 and} the other is converted into an optical signal of wavelength λ ₃ . Here, the bandpass filter 5 has a function of extracting only the frequency component assigned to its own repeater, and its output is input to the control signal detection circuit 6. The control signal detection circuit 6 determines that there is an input from the bandpass filter 5 and that the control signal detection circuit 6 is in the controlled state.

Next, the optical signal of wavelength λ ₂ output from the electrical / optical conversion circuit 10 is multiplexed by the optical multiplexer / demultiplexer 12 via the optical switch 7 and the optical switch 8 and then the optical signal on the next repeater side. It is sent to the fiber transmission line. Further, the optical signal of wavelength λ ₃ output from the electrical / optical conversion circuit 11 is sent to the optical switch 7
And an optical multiplexer / demultiplexer 1 via the optical switch 8 and the optical switch 9.
Are combined and output to the optical fiber transmission line on the monitoring station side.
The monitoring station monitors the returned optical signal of wavelength λ ₃ and online monitors the status of the line up to the repeater for which the loopback test was performed.

The operation at the time of the return control of each switch is as follows. That is, the optical switch 7 outputs an optical signal of wavelength λ ₃ during control and an optical signal of wavelength λ ₂ during non-control. The optical switch 8 outputs the optical signal input during the control to the optical switch 9, and outputs the optical signal input during the non-control to the optical multiplexer / demultiplexer 12. Then, the optical switch 9 outputs an optical signal of wavelength lambda ₃ from the optical switch 8 at the time of control, at the time of non-control outputs the optical signal of the wavelength lambda ₃ from the optical coupler 12.

[0016]

As described above, according to the present invention, the data transmission signal, the control signal and the supervisory signal are wavelength-multiplexed and passed through the same optical fiber transmission line, and the control signal is folded back during the test. Therefore, there is an effect that online monitoring is possible.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of an optical repeater monitoring system according to the present invention.

FIG. 2 is a block diagram showing an example of a conventional optical repeater.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical multiplexer / demultiplexer 2 Optical / electrical converter circuit 3 Electricity / optical converter circuit 4 Optical / electrical converter circuit 5 Band pass filter 6 Control signal detection circuit 7-9 Optical switch 10,11 Electrical / optical converter circuit 12 Optical multiplexer / demultiplexer

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical display location H04B 17/02 D H04J 14/00 14/02 H04B 9/00 U

Claims (2)

[Claims] _1. A _first optical multiplexer / demultiplexer for separating an optical signal of a wavelength λ ₁ for data transmission sent from a monitoring station via an optical fiber transmission line from a multiplexed optical signal, A first optical / electrical conversion circuit for performing optical / electrical conversion of an optical signal having a wavelength λ ₁ separated by a first optical multiplexer / demultiplexer;
A first electric / optical conversion circuit for converting again the electric signal converted by the optical / electrical conversion circuit of _{1 to} an optical signal of wavelength λ ₁ .
Optical / electrical conversion of the optical signal of the wavelength λ ₂ after being separated by the first optical multiplexer / demultiplexer from the optical signal in which the optical signal of the wavelength λ ₂ for return control transmitted from the monitoring station is multiplexed. A second optical / electrical conversion circuit for performing the above, a bandpass filter for extracting a frequency component assigned to each repeater from a signal electrically converted by the second optical / electrical conversion circuit, and this bandpass filter the first makes a determination of the control state from the output of two of the second and third control signal detection circuit which sends a control signal to the optical switch, the wavelength lambda ₂ wavelength optical signals lambda ₂ and wavelength lambda ₃ Second and third electrical / optical conversion circuits for electrical / optical conversion into one optical signal, and one of the outputs of the second and third electrical / optical conversion circuits controlled by the control signal detection circuit. The first optical switch that selects input and outputs When a second optical switch for outputting the output of the first optical switch to one of the output of the control by the two outputs of the control signal detection circuit, the lambda ₂ of the second optical switch Wavelength from the optical fiber transmission line that combines the optical signal output of the wavelength and the optical signal of the wavelength of λ ₁ and outputs to the optical fiber transmission line connected to the next stage repeater a second demultiplexer for separating the optical signal of lambda _3, the wavelength lambda ₃ that is output optical signal of the second wavelength lambda ₃ which are separated from the optical coupler from the second optical switch An optical signal is input, one of the inputs is output under the control of the control signal detection circuit, and an optical signal of wavelength λ ₃ is sent to the first optical multiplexer / demultiplexer connected to the optical fiber transmission line on the monitoring station side. An optical repeater monitoring system comprising a third optical switch. 2. A monitor station via a first optical fiber transmission line.
Data transmission from among the multiplexed optical signals sent as
Signal of wavelength λ ₁ for wavelength and wavelength λ ₂ for loopback control
The optical signals of wavelength λ ₃ are separated from each other.
First optical multiplexing / demultiplexing for transmitting the signal to the first optical fiber transmission line
And a second optical fiber transmission line on the side opposite to the monitoring station
While separating the optical signal of wavelength λ ₃ that is sent ,
The optical signal of long λ _{1 and} the optical signal of wavelength λ ₂ are combined to generate the _second optical signal.
The second optical multiplexer / demultiplexer for sending to the fiber transmission line, and the optical signal of wavelength λ ₂ separated by the first optical multiplexer / demultiplexer.
In addition to this optical signal of wavelength λ _2, an optical signal of wavelength λ ₃ is generated.
Generating means for generating the optical signal of the wavelength λ ₂ separated by the first optical multiplexer / demultiplexer.
From inside to detect whether or not the repeater is under test.
If the test means is detected by the output means and the detection means,
The optical signal having the wavelength λ ₃ generated by the means,
If the light is input to the wave filter and not in the test state, the light of wavelength λ ₂
A signal is input to the second optical multiplexer / demultiplexer, and
The optical signal of wavelength λ ₃ separated by the second optical multiplexer / demultiplexer is
Switch means for inputting to the first optical multiplexer / demultiplexer
Optical repeater monitoring method characterized by the following.