JP2010147674A - Wavelength multiplex optical transmitter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a wavelength multiplex optical transmitter that allows confirmation of the normality of an optical switch without affecting an optical signal in operation during a normal operational state that a failure does not occur. <P>SOLUTION: The wavelength multiplex optical transmitter includes a transmission monitoring control part 4 that successively switches selection of input ports 1 to N executed by an optical switch 3 and determines the normality of the optical switch 3 by the comparison between a B1 byte extracted by any one transmitting transponder, equivalent to the then selected input port, of transmitting transponders 2-1 to 2-N and a B1 byte extracted by a transmitting transponder 2-R. The selection of the input ports 1 to N executed by the optical switch 3 is successively switched during a normal operational state that a failure does not occur in each channel, thereby allowing confirmation of the normality of the optical switch 3 without affecting an optical signal in operation. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a wavelength division multiplexing optical transmission apparatus having an N (N is an arbitrary natural number of 2 or more): 1 redundant configuration using an optical switch.

  In a wavelength division multiplexing optical transmission device that multiplexes and transmits an optical signal of N channels (hereinafter referred to as “ch”), a standby ch is prepared and a failure occurs in any one of the normal chs 1 to Nch. In this case, on the transmitting side, the signal of the channel that has failed due to the optical switch is connected to the standby channel, and on the receiving side, the signal from the standby channel is output to the channel that has failed due to the optical switch. (See, for example, Patent Document 1).

Japanese Patent Laid-Open No. 10-210008 (FIG. 1)

  Since the conventional wavelength division multiplexing optical transmission apparatus is configured as described above, the optical switch on the transmission side and the reception side has a failure when a failure occurs in any one of the normal channels 1 to Nch. It works only when constructing a route that bypasses. Therefore, even when these optical switches fail and the switching operation cannot be performed, it is not possible to detect the failure of the optical switch, and this is the first time when the switching operation is actually performed due to a failure in the normal channel. Since it was found that the optical switch was out of order, it took time to recover, and during that time, there was a problem that the signal was interrupted and the service was greatly affected.

  The present invention has been made to solve the above-described problems, and confirms the normality of the optical switch without affecting the optical signal during operation in a normal operation state where no failure has occurred. An object of the present invention is to obtain a wavelength division multiplexing optical transmission apparatus.

  The wavelength division multiplexing optical transmission apparatus according to the present invention converts optical signals input from each of the N systems into optical signals of different wavelengths, and can identify each system from the optical signals input from each system. Converts the optical signal selected by the regular optical signal transmission means that extracts specific information and the optical signal selection means on the transmission side into an optical signal of a different wavelength, and identifies the selected system from the selected optical signal The standby system optical signal transmission means for extracting specific information and the system selection by the transmission side optical signal selection means are sequentially switched, and the specific information extracted by the normal system optical signal transmission means corresponding to the system selected at that time And transmission monitoring control means for determining the normality of the transmission side optical signal selection means by comparing with the specific information extracted by the standby optical signal transmission means.

  According to the present invention, the selection of the system by the transmission side optical signal selection unit is sequentially switched, and the specific information extracted by the normal optical signal transmission unit corresponding to the system selected at that time and the standby system optical signal transmission unit Since the normality of the transmission side optical signal selection means is determined by comparison with the extracted specific information, transmission is performed in a normal operation state in which no trouble has occurred in the normal optical signal transmission means and the normal optical signal reception means. By sequentially switching the system selection by the side optical signal selection unit, there is an effect that the normality of the transmission side optical signal selection unit can be confirmed without affecting the optical signal in operation.

An embodiment of the present invention will be described below.
Embodiment 1 FIG.
FIG. 1 is a block diagram showing the configuration of a wavelength division multiplexing optical transmission apparatus according to Embodiment 1 of the present invention. In the figure, optical couplers (optical signal branching means) 1-1 to 1-N are inputs of ch1 to chN. The optical signal is branched into two. Transmission transponders (usual optical signal transmission means) 2-1 to 2-N are provided in the subsequent stage of the optical couplers 1-1 to 1-N, and the input optical signals are converted into optical signals having different wavelengths λ1 to λN, respectively. In addition to conversion, a specific byte capable of specifying the channel is extracted from the format of each input optical signal. The optical switch (transmission-side optical signal selection means) 3 selects and outputs one of the input optical signals of ch1 to chN branched by the optical couplers 1-1 to 1-N.

  The transmission transponder (backup optical signal transmission means) 2-R converts the optical signal selected by the optical switch 3 into an optical signal having a different wavelength λN + 1, and can specify the channel from the format of each input optical signal. Extract a specific byte. The transmission monitoring control unit (transmission monitoring control means) 4 sequentially switches the selection of the input ports 1 to N by the optical switch 3 and corresponds to the ch selected at that time among the transmission transponders 2-1 to 2-N. The normality of the optical switch 3 is determined by comparing the specific byte extracted by the transmission transponder with the specific byte extracted by the transmission transponder 2-R. The wavelength multiplexing unit (wavelength multiplexing means) 5 wavelength-multiplexes the optical signals output from the transmission transponders 2-1 to 2-N and 2-R and sends them to the transmission line 6.

  The wavelength separation unit (wavelength separation means) 7 separates the wavelength-multiplexed optical signal received from the transmission line 6 into wavelengths λ1 to λN and λN + 1. The receiving transponders (usual optical signal receiving means) 8-1 to 8-N receive the optical signals separated into the wavelengths λ1 to λN, convert them to the original wavelengths, and output them. The reception transponder (backup optical signal receiving means) 8-R receives the optical signal separated into the wavelength λN + 1, converts it to the original wavelength, and outputs it. The optical switch (reception-side optical signal selection means) 9 selects one channel to which of the ch1 to chN the optical signal from the reception transponder 8-R is transmitted. The optical couplers (optical multiplexing means) 10-1 to 10-N combine the outputs of the optical switch 9 with the optical signals output from the reception transponders 8-1 to 8-N.

  FIG. 2 is a block diagram showing a detailed configuration of the transmission transponder according to Embodiment 1 of the present invention. In the figure, an optical receiver 21 converts an input optical signal into an electrical signal. The reception signal processing unit 22 performs processing on the reception signal, and includes a byte extraction unit 23 that recognizes the format of the reception signal and extracts and outputs a specific byte. The transmission signal processing unit 24 performs signal transmission processing. The optical transmitter 25 converts the optical signal into an optical signal having a specific wavelength and outputs the optical signal.

Next, the operation will be described.
On the transmission side, the ch1 to chN optical signals are branched into two by optical couplers 1-1 to 1-N, respectively, and one of them is input to the transmission transponders 2-1 to 2-N. In the transmission transponders 2-1 to 2 -N, the input optical signals are converted into different wavelengths λ 1 to λN and output to the wavelength multiplexing unit 5. The other branched by the optical couplers 1-1 to 1-N is connected to the optical switch 3. The optical switch 3 selects one of the input optical signals of ch1 to chN and outputs it to the transmission transponder 2-R. The transmission transponder 2-R converts the input optical signal into a wavelength λN + 1 and outputs it to the wavelength multiplexing unit 5. The wavelength multiplexing unit 5 wavelength-multiplexes the wavelengths λ1 to λN and the wavelength λN + 1 and outputs the result to the transmission line 6.

  On the receiving side, the optical signal from the transmission line 6 is separated into wavelengths λ1 to λN and wavelength λN + 1 by the wavelength separator 7. The wavelengths λ1 to λN and the wavelength λN + 1 are input to the reception transponders 8-1 to 8-N and the reception transponder 8-R corresponding to each wavelength. In the reception transponders 8-1 to 8-N, the input optical signals having wavelengths λ1 to λN are converted into the wavelengths of the original ch1 to chN optical signals and output. The reception transponder 8-R converts the input optical signal having the wavelength λN + 1 into the original wavelength, but there is a failure in the apparatus (here, the failure of the transmission transponder or the reception transponder in any one of ch1 to chN). The output is stopped in a state where no occurs. The outputs of the reception transponders 8-1 to 8 -N are combined with the outputs from the output ports 1 to N of the optical switch 9 by the optical couplers 10-1 to 10 -N, respectively. During normal operation, the output of the reception transponder 8-R is stopped, so that no optical signal is output from the output ports 1 to N of the optical switch 9, and the outputs of the reception transponders 8-1 to 8-N are output. The light is output from each of the optical couplers 10-1 to 10-N as it is.

Next, the operation when a failure occurs in any one of ch1 to chN will be described as an example when a failure occurs in the transmission transponder 2-2.
On the transmission side, the optical switch 3 selects and outputs the ch2 optical signal, and the transmission transponder 2-R converts the ch2 optical signal output from the optical switch 3 into the wavelength λN + 1 to the wavelength multiplexing unit 5. The wavelength multiplexing unit 5 multiplexes the wavelengths λ1 to λN and the wavelength λN + 1 excluding the wavelength λ2 and outputs them to the transmission line 6. The failure of the transmission transponder 2-2 is notified to the reception side by a known means not shown here.

  On the reception side, when notified of the failure of the transmission transponder 2-2, the output of the reception transponder 8-2 is stopped. The optical signal of wavelength λN + 1 separated by the wavelength separation means 7 is input to the reception transponder 8-R, converted into the original ch2 optical signal, and output to the optical switch 9. The optical switch 9 selects the output port 2, and couples the optical signal from the reception transponder 8-R with the output of the reception transponder 8-2 corresponding to the wavelength λ2 of the transmission transponder 2-2 in which the failure has occurred. Output to 10-2. At this time, since the output of the reception transponder 8-2 is stopped, the optical coupler 10-2 outputs from the reception transponder 8-R and outputs the optical signal of ch2 via the optical switch 9. As a result, the ch2 optical signal is transmitted while avoiding the failure.

Next, an operation for confirming the normality of the optical switch 3 on the transmission side without affecting the optical signal in operation in the normal operation state in which no failure has occurred will be described.
Here, as an example, a case where the input signal conforms to SDH (Synchronous Digital Hyerarchy, ITU G.707) will be described.
FIG. 3 is an explanatory diagram showing an STM-1 signal format. A frame is composed of 270 bytes × 9 rows, the first 9 bytes of each row is overhead, and the remaining 261 bytes are payloads that contain user data and the like. Here, as an example, the result of parity check for the entire preceding frame is inserted into the B1 byte in the overhead. The result of this parity check is calculated from the bit string of the entire previous frame, and is a pattern specific to this frame.

In FIG. 1, the transmission transponders 2-1 to 2-N and the transmission transponder 2-R convert the input optical signals into different wavelengths λ1 to λN and λR, respectively, and transmit them to the wavelength multiplexer 5 as described above. For output, the B1 byte is extracted from the input optical signal and sent to the transmission monitoring control unit 4.
FIG. 2 shows a specific configuration of the transmission transponders 2-1 to 2-N and 2-R. In FIG. 2, the optical receiver 21 converts the input optical signal into an electrical signal, The received signal processing unit 22 processes received signals. The byte extraction unit 23 in the reception signal processing unit 22 recognizes the format of the reception signal shown in FIG. 3 and extracts and outputs a specific B1 byte. The transmission signal processing unit 24 performs signal transmission processing, and the optical transmission unit 25 converts the optical signal into a specific wavelength optical signal and outputs the optical signal.

  In FIG. 1, the transmission monitoring control unit 4 controls the optical switch 3 to perform switching control at a constant or arbitrary timing to switch the input optical signal connected to the transmission transponder 2-R. For example, the transmission monitoring control unit 4 controls the optical switch 3 to select the ch1 optical signal input to the transmission transponder 2-1, and connect it to the transmission transponder 2-R. At this time, the transmission monitoring control unit 4 compares the pattern of the B1 byte extracted by the transmission transponder 2-1 with the pattern of the B1 byte extracted by the transmission transponder 2-R. If the selection operation of the switch 3 is normal and does not match, it can be determined that the optical switch 3 is not normally selected. The transmission monitoring control unit 4 can determine whether or not all the operations of the optical switch 3 operate normally by performing the same determination for all the input ports of the optical switch 3. This operation has no effect on the signals in operation transmitted by the transmission transponders 2-1 to 2-N, and no additional components are required in the optical signal path. Does not increase the failure rate.

In the first embodiment, STM-1 is used as the signal format. However, the present invention can be similarly applied to other frames such as STM-4, STM-16, and STM-64 of SDH. Further, although the description has been made using the overhead B1 byte as the identification method, any other byte having a unique value of the frame such as the B2 byte can be similarly applied.
Similarly, when the input signal is an OTN frame (ITU-T G.709), the same effect can be obtained by using a parity byte (SM byte or the like) in the overhead.

  As described above, according to the first embodiment, the selection of the input ports 1 to N by the optical switch 3 is sequentially switched, and any of the transmission transponders 2-1 to 2-N corresponding to the ch selected at that time is selected. The normality of the optical switch 3 is determined by comparing the B1 byte extracted by the transmission transponder with the B1 byte extracted by the transmission transponder 2-R. Occasionally, by sequentially switching the selection of the input ports 1 to N by the optical switch 3, there is an effect that the normality of the optical switch 3 can be confirmed without affecting the optical signal in operation.

Embodiment 2. FIG.
FIG. 4 is a block diagram showing the configuration of the wavelength division multiplexing optical transmission apparatus according to Embodiment 2 of the present invention. In the figure, the monitoring light generator (monitoring light generation means) 11 has a wavelength different from the wavelengths λ1 to λN + 1. An optical signal (monitoring light) is generated. The monitoring light insertion unit (monitoring light insertion means) 12 selects either the optical signal from the reception transponder 8-R or the optical signal from the monitoring light generation unit 11. The optical switch (reception-side optical signal selection means) 13 selects one output port to which of the output ports 1 to N + 1 the optical signal selected by the monitoring light insertion unit 12 is transmitted.

  The monitoring light separation units (monitoring light separation means) 14-1 to 14 -N + 1 are provided in the subsequent stage of the optical switch 13, and the optical signals input from the output ports 1 to N + 1 are optical signals from the monitoring light generation unit 11. Are separated into other wavelength components and other wavelength components. The optical signal detectors (optical signal detectors) 15-1 to 15-N are connected to the output ports from which the wavelength components of the optical signals from the monitoring light generator 11 are separated by the monitoring light separators 14-1 to 14-N. The presence / absence of an optical signal (only the wavelength component of the monitoring light) is detected, and the optical signal detection unit (optical signal detection means) 15-N + 1 receives the wavelength component of the optical signal from the monitoring light generation unit 11 by the monitoring light separation unit 14-N + 1. Detects the presence / absence of an optical signal (with the wavelength component of the monitoring light removed) from the output port separated from the output port. Note that these optical signal detectors 15-1 to 15-N + 1 only need to be able to detect the presence or absence of an optical signal, and therefore may have a low-cost and simple configuration. Further, the optical couplers 10-1 to 10-N add the light from the monitoring light separating units 14-1 to 14-N to the optical signals output from the reception transponders 8-1 to 8-N. The output from which the wavelength component of the signal is removed is multiplexed.

  The reception monitoring control unit (reception monitoring control means) 16 performs start and stop control of the monitoring light generation unit 11, selection control of the monitoring light insertion unit 12, and switching control to each output port of the optical switch 13, and insertion of monitoring light The optical signal from the monitoring light generator 11 is selected by the unit 12, the selection of the output port by the optical switch 13 is sequentially switched, and the presence or absence of the optical signal detected by the optical signal detector corresponding to the output port selected at that time Thus, the normality of the optical switch 13 is determined. In addition, the reception monitoring control unit 16 causes the monitoring light insertion unit 12 to select an optical signal from the reception transponder 8-R, and causes the optical switch 13 to select the optical output of the output port N + 1. At that time, the optical signal detection unit 15- The normality of the monitoring light insertion unit 12 is determined based on the presence or absence of the optical signal detected by N + 1.

Next, the operation will be described.
First, an operation when the normality of the optical switch 13 on the receiving side is confirmed without affecting the optical signal during operation in the normal operation state where no failure has occurred will be described.
In FIG. 4, the reception monitoring control unit 16 activates the monitoring light generation unit 11 so that an optical signal (monitoring light) is generated from the monitoring light generation unit 11. Further, the reception monitoring control unit 16 controls the monitoring light inserting unit 12 so that the monitoring light from the monitoring light generating unit 11 is input to the optical switch 13. The reception monitoring control unit 16 controls the optical switch 13 and performs switching control so that the input monitoring light is sequentially output to the output ports 1 to N.

  The monitoring light separators 14-1 to 14 -N connected to the subsequent stage of the output ports 1 to N of the optical switch 13 convert the optical signals input from the output ports 1 to N to the wavelength components of the monitoring light and the other components. The optical signal detectors 15-1 to 15-N detect whether or not there is an optical signal (only the wavelength component of the monitoring light) of each output port from which the wavelength component of the monitoring light is separated. Become. At this time, the reception monitoring control unit 16 collects the detection results from the optical signal detection units 15-1 to 15-N, the monitoring light is detected only at the output port selected by the optical switch 13, and the other output ports Then, it is monitored that no monitoring light is detected. Here, when the monitoring light is not detected from any of the output ports, or when the monitoring light is detected from other than the output port selected by the optical switch 13, it can be determined that the optical switch 13 has failed.

Next, an operation in the case of confirming the normality of the monitoring light inserting unit 12 on the receiving side without affecting the optical signal in operation in the normal operation state where no failure has occurred will be described.
The reception monitoring control unit 16 controls the optical switch 13 so as to select the output port N + 1, and then stops the monitoring light output of the monitoring light generation unit 11 and the reception transponder 8 with respect to the monitoring light insertion unit 12. Control to select an optical signal by -R. The monitoring light separation unit 4-N + 1 connected to the subsequent stage of the output port N + 1 of the optical switch 13 separates the optical signal input from the output port N + 1 into the wavelength component of the monitoring light and the other wavelength components, and the optical signal The detection unit 15-N + 1 detects the presence / absence of the optical signal of the output port N + 1 from which the wavelength component of the monitoring light is separated (excluding the wavelength component of the monitoring light). At this time, if the optical signal detection unit 15-N + 1 detects an optical signal from the reception transponder 8-R, it can be determined that the monitoring light insertion unit 12 is operating normally.

  In this way, the normality of all optical switch operations and paths can be confirmed. Since the monitoring light generated from the monitoring light generator 11 is separated by the monitoring light separators 14-1 to 14-N, the optical signal in operation output from the reception transponders 8-1 to 8-N. The optical switch can be confirmed without affecting the operation. In addition, since the monitoring light separation units 14-1 to 14-N are passive components, an increase in failure rate due to the addition of components can be almost ignored.

  In the second embodiment, the conventional configuration is applied as the transmission side. However, the configuration described in the first embodiment may be applied as the transmission side. In addition to the effect on the receiving side, the effect on the transmitting side of the first embodiment can be achieved.

  As described above, according to the second embodiment, the monitoring light insertion unit 12 selects the optical signal from the monitoring light generation unit 11, sequentially switches the selection of the output port by the optical switch 13, and the output port selected at that time The normality of the optical switch 13 is determined based on the presence or absence of an optical signal detected by the optical signal detection unit corresponding to the By selecting the optical signal by the generation unit 11 and sequentially switching the selection of the output port by the optical switch 13, the normality of the optical switch 13 can be confirmed without affecting the optical signal in operation. is there.

  Further, the monitoring light insertion unit 12 selects the optical signal from the reception transponder 8-R, the optical switch 13 selects the output port N + 1, and the normality of the monitoring light insertion unit 12 is determined depending on the presence or absence of the optical signal detected at that time. Therefore, in the normal operation state where no failure has occurred in each channel, the optical signal from the reception transponder 8-R is selected by the monitoring light insertion unit 12, and the output port N + 1 is selected by the optical switch 13. There is an effect that the normality of the monitoring light insertion unit 12 can be confirmed without affecting the optical signal in operation.

It is a block diagram which shows the structure of the wavelength division multiplexing optical transmission apparatus by Embodiment 1 of this invention. It is a block diagram which shows the detailed structure of the transmission transponder by Embodiment 1 of this invention. It is explanatory drawing which shows the signal format of STM-1. It is a block diagram which shows the structure of the wavelength division multiplexing optical transmission apparatus by Embodiment 2 of this invention.

Explanation of symbols

  1-1 to 1-N optical couplers (optical signal branching means), 2-1 to 2-N transmission transponders (normal optical signal transmission means), 2-R transmission transponders (standby optical signal transmission means), 3 light Switch (transmission side optical signal selection means), 4 transmission monitoring control section (transmission monitoring control means), 5 wavelength multiplexing section (wavelength multiplexing means), 6 transmission path, 7 wavelength separation section (wavelength separation means), 8-1 8-N receiving transponder (usual optical signal receiving means), 8-R receiving transponder (backup optical signal receiving means), 9 optical switch (receiving optical signal selecting means), 10-1 to 10-N optical coupler ( Optical multiplexing means), 11 monitoring light generating section (monitoring light generating means), 12 monitoring light inserting section (monitoring light inserting means), 13 optical switch (receiving side optical signal selecting means), 14-1 to 14-N + 1 monitoring light Separation unit (monitoring light separation hand ), 15-1 to 15-N + 1 optical signal detection unit (optical signal detection unit), 16 reception monitoring control unit (reception monitoring control unit), 21 optical reception unit, 22 reception signal processing unit, 23 byte extraction unit, 24 transmission Signal processing unit, 25 optical transmission unit.

Claims (4)

N (N is an arbitrary natural number greater than or equal to 2) systems that convert optical signals input from each system into optical signals of different wavelengths, and that can identify each system from the optical signals input from each system A regular optical signal transmission means for extracting information;
Optical signal branching means for branching an input optical signal, provided in the preceding stage of the above-mentioned regular system optical signal transmission means,
Transmitting side optical signal selection means for selecting any one of the optical signals of each system branched by the optical signal branching means;
A standby optical signal transmission unit that converts the optical signal selected by the transmission-side optical signal selection unit into an optical signal having a different wavelength and extracts specific information that can identify the selected system from the selected optical signal. When,
The system selection by the transmission side optical signal selection means is sequentially switched, and the specific information extracted by the normal optical signal transmission means corresponding to the system selected at that time and the standby optical signal transmission means are extracted. Transmission monitoring control means for determining the normality of the transmission side optical signal selection means by comparison with the specific information;
A wavelength division multiplexing optical transmission apparatus comprising: a normal optical signal transmission unit; and a wavelength multiplexing unit that multiplexes the optical signals output from the standby optical signal transmission unit. Wavelength separation means for separating the wavelength-multiplexed optical signal into optical signals of different wavelengths in N + 1 (N is an arbitrary natural number of 2 or more) system;
A normal optical signal receiving means for converting optical signals input from each of the N systems of the N + 1 systems separated by the wavelength separating means into optical signals of different wavelengths;
Standby optical signal receiving means for converting an optical signal input from one of the N + 1 systems separated by the wavelength separating means into optical signals of different wavelengths;
Monitoring light generating means for generating an optical signal having a wavelength different from the wavelength of the optical signal after conversion by the standby optical signal receiving means;
Monitoring light inserting means for selecting one of the optical signal after conversion by the standby optical signal receiving means and the optical signal by the monitoring light generating means;
Receiving-side optical signal selection means for selecting one of the N systems to transmit the optical signal selected by the monitoring light insertion means;
Monitoring light separating means provided in the subsequent stage of the N systems of the receiving-side optical signal selecting means, for separating the wavelength components of the optical signal by the monitoring light generating means of the input optical signals;
Optical multiplexing that combines the optical signal output from the regular optical signal receiving means of each system with the optical signal of the corresponding system in which the wavelength component of the optical signal by the monitoring light generating means is removed by the monitoring light separating means. Means,
Optical signal detection means for detecting the presence or absence of an optical signal of each system in which the wavelength component of the optical signal by the monitoring light generating means is separated by the monitoring light separating means;
The monitoring light insertion means selects the optical signal from the monitoring light generation means, and sequentially switches the system selection by the reception-side optical signal selection means, and also detects by the optical signal detection means corresponding to the system selected at that time. And a reception monitoring control means for determining the normality of the reception side optical signal selection means based on the presence or absence of the optical signal to be transmitted. N (N is an arbitrary natural number greater than or equal to 2) systems that convert optical signals input from each system into optical signals of different wavelengths, and that can identify each system from the optical signals input from each system A regular optical signal transmission means for extracting information;
Optical signal branching means for branching an input optical signal, provided in the preceding stage of the above-mentioned regular system optical signal transmission means,
Transmitting side optical signal selection means for selecting any one of the optical signals of each system branched by the optical signal branching means;
A standby optical signal transmission unit that converts the optical signal selected by the transmission-side optical signal selection unit into an optical signal having a different wavelength and extracts specific information that can identify the selected system from the selected optical signal. When,
The system selection by the transmission side optical signal selection means is sequentially switched, and the specific information extracted by the normal optical signal transmission means corresponding to the system selected at that time and the standby optical signal transmission means are extracted. Transmission monitoring control means for determining the normality of the transmission side optical signal selection means by comparison with the specific information;
Wavelength multiplexing means for multiplexing the optical signals output from the regular optical signal transmission means and the standby optical signal transmission means and transmitting them to a transmission line;
Wavelength separation means for separating an optical signal transmitted from the transmission path and wavelength-multiplexed into optical signals having different wavelengths of N + 1 systems;
A normal optical signal receiving means for converting optical signals input from each of the N systems of the N + 1 systems separated by the wavelength separating means into optical signals of different wavelengths;
Standby optical signal receiving means for converting an optical signal input from one of the N + 1 systems separated by the wavelength separating means into optical signals of different wavelengths;
Monitoring light generating means for generating an optical signal having a wavelength different from the wavelength of the optical signal after conversion by the standby optical signal receiving means;
Monitoring light inserting means for selecting one of the optical signal after conversion by the standby optical signal receiving means and the optical signal by the monitoring light generating means;
Receiving-side optical signal selection means for selecting one of the N systems to transmit the optical signal selected by the monitoring light insertion means;
Monitoring light separating means provided in the subsequent stage of the N systems of the receiving-side optical signal selecting means, for separating the wavelength components of the optical signal by the monitoring light generating means of the input optical signals;
Optical multiplexing that combines the optical signal output from the regular optical signal receiving means of each system with the optical signal of the corresponding system in which the wavelength component of the optical signal by the monitoring light generating means is removed by the monitoring light separating means. Means,
Optical signal detection means for detecting the presence or absence of an optical signal of each system in which the wavelength component of the optical signal by the monitoring light generating means is separated by the monitoring light separating means;
The monitoring light insertion means selects the optical signal from the monitoring light generation means, and sequentially switches the system selection by the reception-side optical signal selection means, and also detects by the optical signal detection means corresponding to the system selected at that time. And a reception monitoring control means for determining the normality of the reception side optical signal selection means based on the presence or absence of the optical signal to be transmitted. The receiving side optical signal selection means is:
It is assumed that one system is selected as to which of the N + 1 systems the optical signal selected by the monitoring light insertion means is transmitted to,
An optical signal detecting means provided at the subsequent stage of the N + 1 system of the receiving side optical signal selecting means for detecting the presence or absence of an input optical signal;
Reception monitoring control means
The optical signal after the conversion by the standby optical signal receiving means is selected by the monitoring light inserting means, the N + 1 system is selected by the receiving side optical signal selecting means, and the monitoring light is determined depending on the presence or absence of the optical signal detected at that time. 4. The wavelength division multiplexing optical transmission apparatus according to claim 2, wherein normality of the inserting means is determined.

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