JPH0738508A - Optical communication equipment - Google Patents

Abstract

PURPOSE:To easily multiplex both user information and managing information regardless of the transfer code or transfer format by allocating the user information and managing information to different frequency bands, which are not overlapped each other, and transmitting the information while converting it into optical signals. CONSTITUTION:A multiplex modulation part 10 allocates the managing information inputted from a managing information input port 11 and the user information inputted from a user information input port 13 to the different frequency bands which are not overlapped each other. An electrooptic transducing part 15 transduces an electric signal outputted from the multiplex modulation part 10 to the optical signal and outputs it to an optical transmission line 20. An optoelectric transducing part 25 transduces this optical signal to an electric signal. A second filter 31 of a demodulation part 30 is composed of a band filter for passing only the user information, and the user information is extracted from a user information output port 32. The modulated managing information is extracted from a first filter 33 of the demodulation part 30, this is demodulated by an electric demodulation part 34, and the managing information is outputted from a managing information output port 35.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical communication device for multiplexing communication information generated by an electric signal, converting it into an optical signal and transmitting it.

[0002]

2. Description of the Related Art In various communication systems that have been widely adopted conventionally, in addition to user information that is actually required to be transmitted as communication information, this user information is monitored in order to be transmitted without error. Management information for maintenance and operation of relay devices. Therefore, when transmitting and receiving user information, such management information must be transmitted to the other party without error. The form of the transmission signal includes an analog signal and a digital signal. Furthermore, as its transmission format, PDH
There are (time-division multiplexing) system and SDH (synchronous digital hierarchy) system. User information and management information generated by these methods are multiplexed and transmitted / received by a certain method.

FIG. 2 shows an explanatory view of a conventional optical communication system.
This device is a diagram for explaining a digital multiplex transmission system in the case of multiplexing and transmitting conventional user information and management information on an optical transmission line. This system transmits signals in a format called 2M highway format. In this case, 1 millisecond (ms) is used as a reference, and this is divided into eight, and time is allocated to each one frame. For example, the first frame shown in this figure is composed of 32 time slots in total. The length of one frame is 125 microseconds (μs). Then, the management information A is included in the 0th time slot, and the user information B is included in the remaining 1st to 31st time slots. In a conventional optical communication device, a digital signal of the above format is generated in advance, and this is converted into an optical signal for transmitting / receiving information.

[0004]

The conventional optical communication device as described above has the following problems to be solved. For example, in the optical communication system as shown in FIG. 2, if there is user information previously composed of an analog signal or the like, this is converted into a digital signal, appropriately divided together with the digitized management information, and then fixed. Make up a frame of length. As described above, in order to match the user information and the management information with the same defined transfer format in advance, a relatively complicated multiplexing device is required. Furthermore, different conversion codes and transfer formats of original signals require different conversion / multiplexing circuits.

Therefore, it is necessary to prepare a conversion device suitable for each conversion for each different transfer code or transfer format of user information, and to perform multiplexing, which complicates the process and increases the cost of the device. It was. The present invention has been made by paying attention to the above points, and user information and management information generated by a relatively free transfer code or transfer format can be easily multiplexed by the same conversion device and transmitted as an optical signal. It is an object of the present invention to provide an optical communication device capable of performing the above.

[0006]

The optical communication device of the present invention comprises:
A management information input port that receives management information used for communication management, a user information input port that receives user information to be communicated, management information that is input from the management information input port, and a user that is input from the user information input port A multiplexing modulator that allocates information to different frequency bands that do not overlap each other, and an electrical / optical converter that converts an output signal of the multiplexing modulator into an optical signal,
From the optical transmission line that transmits the output of the electric / optical conversion unit, the optical / electrical conversion unit that receives the output of the optical transmission line and converts it into an electric signal, and the electric signal that the optical / electrical conversion unit outputs, It is characterized in that it is provided with a demodulation section for separating and outputting the management information and the user information which are respectively assigned to different frequency bands.

[0007]

This device allocates a certain frequency band to the user information and the management information in advance, and sets the carrier wave of the management information in an area that does not overlap with the user information. The electric signal thus obtained is converted into an optical signal and transmitted. The receiving side separates the signals by the reverse procedure. This allows
User information and management information are easily multiplexed regardless of the transfer code or transfer format.

[0008]

The present invention will be described in detail below with reference to the embodiments shown in the drawings. FIG. 1 is a block diagram showing an embodiment of an optical communication device of the present invention. The apparatus shown in the figure includes a multiplexing modulator 10, an electric / optical converter 15 that receives the output, an optical transmission line 20 that transmits the output, and an optical / electric converter 25 that receives the output of the optical transmission line 20. , And a demodulation unit 30 that demodulates the received signal. The multiplexing modulator 10 receives the signal input from the management information input port 11 and the electrical modulator 12 that receives the signal received from the user information input port 13 and the output of the electric modulator 12 to multiplex the signals. It is composed of the multiplexing unit 14.

The electrical / optical conversion section 15 includes a multiplexing modulation section 10
The light emitting device 16 is provided for converting an electric signal output by the device into an optical signal. The light emitter 16 is composed of, for example, a laser diode or the like. The optical transmission line 20 includes the electrical / optical conversion unit 1
5 is composed of an optical fiber or the like for transmitting the optical signal output. The optical / electrical conversion unit 25 includes a photodetector 26. The photodetector 26 is composed of, for example, an avalanche photodiode or the like, and includes an element or the like for converting the received optical signal into an electric signal according to the intensity.

The demodulation section 30 comprises a second filter 31, a user information output port 32 for extracting its output, a first filter 33, an electric demodulation section 34, and a management information output port 35 for extracting these outputs. . FIG. 3 is a diagram for explaining the operation of the multiplexing modulator 10, where (a) is an explanatory diagram of frequency band allocation of the management information input port,
(B) is a frequency band allocation explanatory diagram of the management information after modulation, (c) is a frequency band allocation explanatory diagram of user information.

As shown in (a), for example, the management information A is composed of a signal within a maximum f1 Hz range. This signal may be an analog signal or a digital signal. The electric modulator 12 shown in FIG. 1 modulates a carrier wave having a frequency of f2 Hz by using such management information A. As a result, as shown in (b), the management information A after modulation has a center frequency of f2 Hz equal to that of the carrier wave and (f2-f1) Hz.
The electric signal has a band of (f2 + f1) Hz. Further, in the present invention, as shown in (c), the user information B is assigned to the frequency band of maximum f3 Hz. This frequency f3 Hz is selected to be a value lower than (f2-f1) Hz.

FIG. 4 is a diagram for explaining frequency band allocation of multiple signals. The electric multiplexing unit 14 shown in FIG. 1 multiplexes the management information A and the user information B as shown in FIGS. 3B and 3C. As a result, an output signal having a frequency distribution as shown in FIG. 4 is obtained. As is clear from this signal, the output of the multiplexing modulator 10 shown in FIG.
The user information B is assigned between the frequencies 0 Hz and f3 Hz, and the management information A is assigned to the band (f2-f1) Hz to (f2 + f1) Hz above the user information B. Such an electric signal corresponds to the electric signal shown in FIG.
The light is converted into an optical signal in the optical converter 15.

FIG. 5 is an explanatory diagram of optical frequency allocation in the optical transmission line. In this graph, the optical frequency is plotted on the horizontal axis and the signal intensity is plotted on the vertical axis. As shown in this figure,
The output signal of the light emitter 16 at is a signal symmetrical about the light emitter frequency fl1. That is, actually, an optical signal having a frequency of fl1 is modulated by an electric signal as shown in FIG. 4 and sent to the optical transmission line 20. Therefore, in this case, the management information A is changed from {fl1- (f2 + f1)} to {fl1.
It is distributed between − (f2-f1)} and between {fl1 + (f2-f1)} and {fl1 + (f2 + f1)}. Also, the user information B is from (fl1-f3) to (fl1
It will be distributed in the range of + f3).

The optical / electrical converter 25 shown in FIG. 1 converts the optical signal having the contents shown in FIG. 5 into an electric signal to obtain a multiplexed signal as shown in FIG. The second filter 31 of the demodulation unit 30 is composed of a bandpass filter that passes only user information. The first filter 33 is composed of a bandpass filter that passes only the management information. It should be noted that the electric demodulation unit 34 uses the carrier wave f output from the first filter 33.
The second management information A is detected and only the management information A is extracted from the detection circuit.

FIG. 6 is a frequency characteristic explanatory diagram of the first filter 33 and the second filter 31 of the demodulation unit 30 as described above. As shown in (a), the first filter 33 is composed of, for example, a high-pass filter that passes an electric signal having a frequency of f4 or higher. The first pass area WA is set to a range that includes the entire management information A shown in FIG. 4 and does not include the user information B. That is, the frequency f4 is set sufficiently higher than the frequency f3 and sufficiently lower than the frequency (f2-f1).

(B) is the frequency characteristic of the second filter, f
It is composed of a low-pass filter that passes an electrical signal of 4 Hz or less. The second pass band WB is a region sufficient to pass the user information B having the frequency f3 or less shown in FIG. Through such processing, the user information B as shown in FIG. 3C is extracted from the user information output port 32 of the demodulation unit 30.

Further, the modulated management information A as shown in FIG. 3B is taken out from the first filter 33 of the demodulation unit 30 shown in FIG. The electric demodulation unit 34 demodulates the electric demodulation unit 34 to obtain the management information A as shown in FIG. This is output from the management information output port 35 of the demodulation unit 30 shown in FIG. By the above processing, the device of the present invention multiplexes the user information and the management information, converts them into optical signals, and transmits them.

FIG. 7 shows a block diagram of a modified example of the multiplexer according to the present invention. In this embodiment, the electrical / optical conversion unit 1
5, the optical signal is multiplexed. In this example, the optical multiplexer 17 has an N-wave multiplexing configuration, and has a configuration in which optical signals of N types of wavelengths are combined and output toward an optical transmission line. It is to be noted that such an optical multiplexer 17 has a structure in which, for example, a large number of optical fibers are bundled and connected to one optical fiber.

Further, the demultiplexing device which receives the output of the above-mentioned multiplexing device through the optical transmission line is constructed as follows. FIG. 8 shows a modified block diagram of the separation device according to the present invention. In the device shown in the figure, the optical / electrical converter 25 is provided with an optical distributor 27 and an optical filter 28. The structure of the demodulation unit 30 is exactly the same as that of the embodiment shown in FIG. The optical distributor 27 is composed of an optical circuit in which the optical multiplexer 17 is connected in reverse, and an optical filter 28 is connected to each output side thereof so that only light in a certain wavelength range is directed to the photodetector 26. It is configured to be output. In the above modification, the format of the signal output from the light emitter 16 shown in FIG. 7 is the same as that already described using the embodiment of FIG. However, the plurality of light emitters 16 connected to the optical multiplexer 17 emit light of different wavelengths.

FIG. 9 (a) shows an explanatory view of the operation of the modified apparatus. Each of the light emitters 16 connected to the optical multiplexer 17 shown in FIG.
It emits light of N kinds of wavelengths up to N. Therefore, FIG.
As shown in (a), the optical signal output from the electrical / optical conversion unit 15 includes management information A1 to
It includes A3 and user information B1 to B3. That is, the management information A1 and the user information B centering on the wavelength fl1
1 is assigned. Management information A centering on wavelength fl2
2 and user information B2 are assigned. Similarly, the management information A3 and the user information B3 are allocated around the wavelength flN.

When such a signal is input to the separation device shown in FIG. 8, the optical / electrical converter 25 uses the optical filter 28 to extract only the signal in a specific region. That is, FIG.
In the example shown in (b), the pass band of the optical filter 28 is set to W1.
To frequency (fl1 + f2 + f1) to (fl1-f
The optical signal in the range of 2 + f1) is detected by the photodetector 26 shown in FIG.
Send to. As a result, the demodulation unit 30 described below extracts only the management information A1 and the user information B1. As described above, the user information and the management information are frequency-multiplexed in advance at the stage of electric signals, and when there are a plurality of such signals, frequency-multiplexing is performed at the stage of optical signals. Send it to the transmission line. Therefore, regardless of the signal format, the multiplexing can be performed relatively easily without being affected by the transfer code or the transfer format of the user information or the management information.

The present invention is not limited to the above embodiments. In general, management information is composed of relatively simple data, so an example was shown in which the frequency band of management information was set relatively narrow and the frequency band of user information was set wide, but any setting may be set wide. Absent. Also, an example in which only the management information is modulated by the electric modulator has been described, but both the user information and the management information may be modulated, or only the user information may be modulated. Further, regarding the configuration of the electrical / optical conversion unit and the optical transmission line, the configuration of the optical / electrical conversion unit, and the like, various circuits having the same function that are well known in the art may be used.

[0023]

According to the optical communication device of the present invention described above, no matter what kind of transfer code or transfer format the user information or management information is composed of, the respective pieces of information do not overlap each other in advance and are different from each other. By allocating to the frequency band, the multiplexing by the electric signal is easily performed. If this is converted into an optical signal, the user information and the management information can be easily separated on the receiving side by a simple circuit such as a filter. In addition, although the band of the signal is limited, the format etc. are not limited, and therefore, regardless of whether the original signal is an analog signal or a digital signal, preprocessing such as conversion to a signal of a fixed format for multiplexing is required. Therefore, the circuit configuration on the transmission side can be sufficiently simplified.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of an optical communication device of the present invention.

FIG. 2 is an explanatory diagram of a conventional optical communication system.

FIG. 3 is a diagram for explaining the operation of the multiplexing modulator of the device of the present invention,
(A) is a frequency band allocation of the management information input port,
(B) is a frequency band allocation of the management information after modulation,
(C) is frequency band allocation of user information.

FIG. 4 is an explanatory diagram of frequency band allocation of multiple signals.

FIG. 5 is an explanatory diagram of optical frequency allocation in an optical transmission line.

FIG. 6 is an explanatory diagram of frequency characteristics of a filter of a demodulation unit.

FIG. 7 is a block diagram of a modified example of the multiplexing device of the present invention.

FIG. 8 is a block diagram of a modified example of the separation device of the present invention.

FIG. 9 is an operation explanatory view of the apparatus of the modified example.

[Explanation of symbols]

 10 Multiplexing Modulator 11 Management Information Input Port 13 User Information Input Port 15 Electric / Optical Converter 20 Optical Transmission Line 25 Optical / Electrical Converter 30 Demodulator 32 User Information Output Port 35 Management Information Output Port

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Claims (1)

[Claims] 1. A management information input port for receiving management information used for communication management, a user information input port for receiving user information to be communicated, management information input from the management information input port, and the user information input. A multiplexing modulator that assigns user information input from a port to different frequency bands that do not overlap each other, and an electrical / electrical converter that converts an output signal of the multiplexing modulator into an optical signal.
An optical conversion unit, an optical transmission line for transmitting the output of the electric / optical conversion unit, an optical / electrical conversion unit for receiving the output of the optical transmission line and converting it into an electric signal, and an output of the optical / electrical conversion unit. An optical communication device, comprising: a demodulation unit that separates and outputs the management information and the user information, which are assigned to different frequency bands, from the electric signal to be output.