JP2000244545A - Device and method for optical reception - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical transmission system capable of omitting the transmission of additional information for training at the time of operation to transmit data from a slave station to a master station. SOLUTION: During a training term T1 to be run before an operating term T2 for transmitting data to be originally transmitted, training data concerning respective slave stations 611-613 are sent to the master station. The master station measures the generation timing of reception levels or reception data for each of slave stations 611-613 while using these training data and stores the result in a storage part. During the following operating term T2, concerning optical signals 611-613 sent from the slave stations 611-613, the generation timing of reception levels or reception data thereof is adjusted by a value stored in the storage part. Since data for adjustment are stored during the training term T1, the transmission of the additional information for training during the operating term T2 can be omitted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical receiving apparatus for receiving data transmitted from a slave station using an optical fiber, and an optical receiving method for receiving such data. The present invention relates to an optical receiving device and an optical receiving method that are improved.

[0002]

2. Description of the Related Art With the development of communication technology, the amount of communication of digital data has increased dramatically. In order to cope with such an increase in the amount of communication, optical communication has been used as an information transmission means in place of telecommunications in transmission systems of the backbone system. A transmission device using an optical fiber for transmitting an optical signal can dramatically improve the transmission capacity as compared with a conventional device.

[0003] With the rapid spread of the Internet, it is believed that the demand for transmission capacity will continue to increase. In order to cope with such demand, recently, FTTH (Fi
ber To The Home) is being actively researched. However, these studies require additional information to establish burst data communication. Therefore, there is an urgent need to improve the transmission efficiency of the transmission device on the subscriber side.

FIG. 10 shows a configuration of a conventional optical transmission system. The first to Nth slave stations 11 _{1 to} 11 _N (N
Is an integer of 2 or more) is connected to the master station 13 via a branching device called a coupler 12. Each slave station 11 _1-
11 _N optical signals 14 ₁ to 14 _N to be transmitted from the coupler 1
2 are combined as an optical signal 15 and input to the 3R unit 16 in the master station 13.

[0005] The 3R section 16 performs re-shaping, re-generating, and re-timing of the received optical signal.
g), and includes a measuring unit 17 and a control unit 18 for performing various controls. Here, reshaping refers to a process of regenerating an electric signal from an optical signal by linear amplification, and regenerating refers to a process in which a digital circuit such as a serial-parallel conversion circuit or a frame synchronization circuit (not shown) at the next stage is used. TTL to interface
And a step of setting a signal level such as ECL. Also,
Timing refers to a process of extracting a clock from an optical signal and synchronizing the phase with a data signal.

[0006] The measuring unit 17 measures the reception level and the generation timing of the received data every time the optical signal 15 is received. The control unit 18 converts the measurement information thus obtained by the measurement unit 17 into an electric signal 21 and supplies it to the reception data processing unit 22 as valid reception data. The reception data processing unit 22 performs processing for transmitting the reception data to a core optical fiber (not shown).

FIG. 11 shows a state of transmission of each optical signal during system operation in the conventional optical transmission system. In this figure, the vertical axis represents the light receiving level of the data measured by the measuring unit 17 of FIG. 10, and the horizontal axis represents the passage of time. Here, for the sake of simplicity,
The third slave station 11 ₁ to 11 ₃ are repeated shall divisionally performed at the transmission of the optical signal (transmission data) 14 _{1-14 3.}

[0008] First the first slave station 11 ₁ to a time starting at time t ₁ sends out the optical signal 14 _1. The tip portion of the optical signal 14 _1, training data 31 ₁ is disposed. Training data 31 ₁ is measured by the measuring unit 17 as described above. The reception data processing unit 22 performs training so that the light reception level indicated by the electric signal 21 is received as appropriate data by the master station. this is,
Even if the first slave station 11 ₁ sends out an optical signal at a predetermined transmission level, the first slave station 11 ₁ and the master station 13
Depending on factors such as distance relationship with the station and fluctuations in temperature, etc.
This is because the reception level of the optical signal on the third side fluctuates and the signal waveform of the analog level is distorted. This is because training needs to be performed.

[0009] After the training, such as described above for the first slave station 11 ₁ has been performed, the data portion 32 ₁ to be originally transmitted in the optical signal 14 ₁ is transmitted. Next, the second slave station 1
1 data portion 32 ₂ to be originally transmitted optical signal 14 ₂ after the completion of the training is likewise transmitted training data ₃₁₂ is also ₂ is transmitted. And then,
The third slave station 11 ₃ in the same manner for the training data 3
1 ₃ is a data portion 32 ₃ to be the original transmission of optical signals 14 ₃ after the training is completed sent are transmitted. Hereinafter, the process for data transmission is repeated in the same manner.

As described above, in the conventional optical transmission system described with reference to FIGS. 10 and 11, every time each slave station transmits burst data, the receiving side performs training for adjusting the level of the optical signal and the like. Is going. For this reason, the data portion 32 to be originally transmitted cannot be transmitted for the duration of the training, and there is a problem that the transmission efficiency of communication is reduced.

FIG. 12 shows an outline of a configuration of an optical transmission system in which training for each adjustment of the level of an optical signal in training can be omitted. In FIG. 12, the same portions as those in FIG. 10 are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

In this system proposed in Japanese Patent Application Laid-Open No. 9-69818, the optical level adjusting section 41 is provided in the master station 13A connected to the _first to _Nth slave stations 111 to 11N via the coupler 12. The optical signal whose level has been adjusted by the optical level adjusting unit 41 is input to and received by the optical transceiver 42, or the optical signal output from the optical transceiver 42 is adjusted and output. It has become so.

The optical transmitter / receiver 42 receives the transmission signal 45 and outputs a reception signal 46. The reception signal 46 in the test communication performed prior to the actual communication is input to the reception level measuring unit 47. The reception level at that time is measured. The light level control unit 48 adjusts the light level in the light level adjustment unit 41 based on the measured reception level, and sets the reception level to an optimum value. When the reception level is set to the optimum level, the adjustment value is written to the memory 49. Based on this, in an actual communication, the adjustment value is read from the memory 49 and the light level adjustment unit 41 adjusts the light level. Japanese Patent Laid-Open Publication No. Hei 10-507893 discloses a technique for measuring the peak value of each burst signal to obtain an amplification coefficient, and has the same technical idea as Japanese Patent Laid-Open Publication No. Hei 9-69818.

[0014]

In the optical transmission system proposed in Japanese Unexamined Patent Publication No. 9-69818 shown in FIG. 12, only the adjustment of the reception level of the optical signal in the training described in FIGS. This is done prior to operation. However, even if the reception level of the optical signal is adjusted for each slave station, the distortion of the waveform of the optical signal actually transmitted from those slave stations is not corrected. Therefore, in the conventional optical transmission system, even if it is possible to shorten the training period by measuring the reception level and reading it out during actual operation, the optical signal transmitted from each slave station can be shortened. It was still necessary to add a training signal to the head.
For this reason, a signal sent from each slave station to the master station always has additional information, and there has been a problem that transmission efficiency cannot be sufficiently improved.

An object of the present invention is to provide an optical receiving apparatus and an optical receiving method which can omit transmission of additional information for training when data is sent from a slave station, for example. It is in.

[0016]

According to the first aspect of the present invention, (a) a reception level adjusting means for receiving an optical signal and adjusting the reception level to a predetermined signal level;
(B) generation timing adjusting means for adjusting the timing for reproducing the digital signal transmitted based on the optical signal; and (c) transmitting data to be transmitted from one or more devices on the transmission side. Adjustment data measurement for measuring the adjustment data used for adjustment by the reception level adjustment unit and the generation timing adjustment unit for each transmitting station based on the training data sent during the training period prior to the operation period. Means, (d) storage means for storing the adjustment data measured by the adjustment data measurement means for each transmission-side apparatus, and (e) adjustment data for the transmission-side apparatus currently receiving from the storage means. Read and adjust the reception level adjusting means and the generation timing adjusting means to receive the optical signal transmitted from the transmitting device. To and a signal receiving means to the light receiving device.

That is, according to the first aspect of the present invention, a training period is set and the training data is transmitted before the transmitting device for transmitting the optical signal sends the data to be transmitted. The adjustment data for adjusting the reception level is measured by the reception level adjustment means based on the training data sent during the period, and the timing for reproducing the digital signal is adjusted using the generation timing adjustment means. Adjustment data is measured. These adjustment data are stored and stored in the storage means for each device on the transmission side. In the operation period after the training period, the adjustment data is read out from the storage unit and adjusted for each device on the transmission side, so that it is not necessary to transmit additional information for training in the operation period.

According to a second aspect of the present invention, the reception level adjusting means and the generation timing adjusting means in the optical receiving apparatus according to the first aspect comprise optical signal reshaping means for reproducing an electric signal from an optical signal by linear amplification. Retiming means for extracting a clock from a signal converted into an optical signal or an electric signal, and regenerating means for converting the signal level into a signal level for interfacing with a digital circuit of the next stage. It is characterized by: Each of these means will be specifically described later.

According to a third aspect of the present invention, in the optical receiving apparatus according to the first aspect, the reception level adjusting means includes an optical-electrical converting means for converting the received optical signal into an electric signal, and a signal of the converted electric signal. A gain adjusting means for adjusting the level to a predetermined level; a generation timing adjusting means for extracting a clock for reproduction based on the received optical signal; and an electric generator using the extracted clock. And data identification means for generating data transmitted from the signal.

According to the fourth aspect of the present invention, (a) a training data transmitting step of sequentially transmitting predetermined training data to a plurality of slave stations to the master station;
(B) When the training data is sequentially sent from the plurality of slave stations, the reception level of the digital signal as the data sent from the slave stations becomes a predetermined signal level based on the training data. Obtaining the first adjustment data for adjusting the timing and the second adjustment data for adjusting the timing for reproducing the digital signal, and (c) obtaining the adjustment data for the plurality of slave stations. When the training data is transmitted from the plurality of slave stations in the (d) training data sending step, the plurality of slave data are stored in the storage step of storing the adjustment data in a predetermined storage unit for each slave station. A data transmission operation start step for starting transmission of data to be transmitted to the station; The respective slave stations in the transmission operation start step of a slave station corresponding to each that transmits data 1
And an operation data receiving step of reading the second adjustment data from the storage unit and adjusting the reception level and the timing for reproduction of the data received from the corresponding slave station based on the readout data and the second adjustment data. Let it.

In other words, according to the present invention, the training data is transmitted to the master station before the plurality of slave stations start the communication of the data to be transmitted, and the master station transmits the received data during the training period. Based on this, the first and second adjustment data are acquired, stored in a predetermined storage unit, and the operation period is shifted. In the operation start period, the reception level of data received from the relevant slave station and the timing for reproduction are adjusted. This eliminates the need for each slave station to transmit additional information for training to the master station during the operation period.

According to the fifth aspect of the present invention, there is provided (a) a first method for adjusting a reception level of a digital signal as data transmitted from a plurality of slave stations which are to receive data. A confirmation step of confirming whether the adjustment data and the second adjustment data for adjusting the timing for reproducing the digital signal are stored in a predetermined storage section; and (b) the first and second confirmation steps are performed in this confirmation step. A training data transmitting step of transmitting predetermined training data to the master station side for a slave station whose adjustment data is not stored in the storage unit;
And an adjustment data acquisition step of acquiring first and second adjustment data based on the training data when the training data is sent from a slave station whose second adjustment data is not stored in the storage unit. D) Adjustment data acquisition step The adjustment data storage step of storing the acquired first and second adjustment data in the storage unit, and (E) each of the first and second adjustment data stored in the storage unit Every time each slave station transmits data to the slave station, the first and second adjustment data of the corresponding slave station are read from this storage unit and received from the corresponding slave station based on these. An operation data reception step of adjusting a data reception level and a reproduction timing is provided in the optical reception method.

[0023] The invention according to claim 5 deals with a contrivance for a case where there is a slave station storing the first and second adjustment data in the storage unit and a slave station not yet storing the same. . That is, in the present invention, in the confirmation step, it is confirmed whether or not the storage unit stores the first and second adjustment data in the storage unit. The training data is sent to the master station. Therefore, in the case of the slave station in which the first and second adjustment data are already stored in the storage unit, the actual operation can be performed without further going through the training period, and the transmission period of the training data and the training data Can be omitted.

According to a sixth aspect of the present invention, there is provided the optical receiving method according to the fourth or fifth aspect, wherein (a) a predetermined setting is provided for the slave station storing the first and second adjustment data in the storage unit. Re-transmitting the training data when the condition is satisfied, and acquiring new first and second adjustment data;
(B) When new first and second adjustment data are obtained, the first and second adjustment data for the slave station stored in the storage unit are replaced with new first and second adjustment data. A latest data replacement step.

In other words, according to the sixth aspect of the present invention, the training data is also supplied to the slave stations storing the first and second adjustment data in the storage unit when the condition for rewriting these adjustment data is satisfied. The first adjustment data and the second adjustment data are rewritten and updated to the latest data, so that the reliability of the received data is ensured. Also in this case, it is natural that transmission can be performed more efficiently than in the related art in which data is always transmitted with additional information.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to embodiments.

FIG. 1 shows an optical communication system using an optical receiver according to an embodiment of the present invention. The first to Nth slave stations 61 _{1 to} 61 _N (N is an integer of 2 or more) are connected to a master station 63 via a coupler 62. Optical signal transmitted from each child station 61 ₁ ~61 _N 64 ₁ ~64 _N
Are combined as an optical signal 65 by the coupler 62 and the master station 6
3 is input to the 3R unit 66.

The 3R unit 66 re-shapes the received optical signal in the same manner as described with reference to FIG.
And a part for performing re-generating and re-timing. The 3R unit 66 according to the present embodiment includes a measuring unit 67 that inputs the received optical signal 65 and performs sparse measurement, a storage unit 68 that writes various data obtained by the measurement, and a control unit 69 that performs various controls. It is constituted by. The control unit 69 performs re-shaping, re-generating and re-timing based on the optical signal 65 received during operation, and inputs the obtained electric signal to the reception data processing unit 72 as reception data 71. It has become.

The reception data processing section 72 performs processing for transmitting the input reception data 71 to a main optical fiber (not shown). Further, the reception data processing section 72 outputs slave station number information 74 indicating the number of the slave station requesting transmission of the optical signal 64.
Is supplied to the storage unit 68, and read
A write signal 75 is supplied to issue an instruction to write data 76 and an instruction to read stored data 77. The storage unit 68 according to the present embodiment is configured by a nonvolatile memory in order to prevent data loss.

The 3R section 66 of this embodiment has a circuit configuration similar to that of a normal personal computer in which some electronic circuits are connected via an input / output interface circuit (not shown). The 3R unit 66 includes a CP (not shown).
U (central processing unit). Then, the storage unit 68
Is stored in a storage medium such as a hard disk or a semiconductor memory which includes a part thereof, and by executing this program, various kinds of control described later are performed. Note that the 3R unit 66 and the reception data processing unit 72 can share a control computer part.

FIG. 2 is for explaining the circuit operation of the 3R section, and FIG. 3 shows the waveform of each section.
In this description it is assumed that the optical signal 64 ₁ sent from the first slave station 61 ₁ as an example is processed in 3R section 66.

As shown in FIG. 3A, the first slave station 61 ₁
The optical signal 64 ₁ output from the digital signal is a digital signal without ternary distortion. The optical signal 64 ₁ is transmitted to the transmission line 81 ₁
At the time when the signal is input to the 3R unit 66 through the step (b), the waveform is distorted as shown in FIG. The 3R section 66 includes an equalizing circuit 83 for reshaping, and the equalizing circuit 83
A timing extraction circuit 84 for extracting a timing clock and an identification circuit 85 for regenerating are provided.

FIG. 4 shows a specific configuration example of the equalization circuit. The equalizing circuit 83 has a photodiode 92 for inputting the optical signal 64 and converting it into an electric signal 91.
A preamplifier 93 for receiving the electric signal 91 and converting the current signal into a voltage signal;
, And a linear amplifier 95 that linearly amplifies the output 94. The linear amplifier 95 is used to amplify a signal having a very small voltage level to a voltage level that can be easily processed by a subsequent circuit. The electric signal 96 output from the equalizing circuit 83 has been subjected to waveform shaping as shown in FIG.

The timing extraction circuit 84 shown in FIG. 2 detects the local maximum value and the local minimum value of the electric signal 95 to extract the timing clock 97 as shown in FIG. The timing extraction circuit 84 extracts a sine wave of a clock component using a band-pass filter having a pass band of a clock frequency, and generates a rectangular wave clock using a limiter amplifier (TAN).
K) circuit or PLL circuit can be used.

The timing clock 97 extracted from the timing extracting circuit 84 is supplied to the discriminating circuit 85, and the received data 71 (FIG. 3 (e)) is output as a digital signal synchronized with its rise. As the identification circuit 85, a flip-flop circuit is generally used.

FIG. 5 shows how an optical signal is transmitted from each slave station to the master station in the optical transmission system of this embodiment. Preceding the the conventional layout shown in FIG. 11 are arranged training data 31 ₁ to 31 ₃ in the optical signal 14 _{1-14 3} their top portion first to third slave stations 11 ₁ to 11 ₃ are sent and although, in this embodiment, first there is a training period T _1, followed by operation period T ₂ is this adapted to continue. Note that some systems if the operation period T ₂ prolonged can sandwich the appropriate training period T ₁ therebetween.

In this optical transmission system, the master station 63
Is an optical signal 6 for each of the slave stations 61 _{1 to} 61 _N in order.
41 ₁ to 64 _N are requested, and the respective slave stations 61 _{1 to} 61 _N are individually requested to transmit optical signals 64 ₁ to 64 _N.
Is sent to the master station 63. In the training period T _1, first request transmission of optical signals for training the parent station 63 is for example first slave station 61 _1, the first
Slave station 61 ₁ responds to this as long as a state capable of communicating to deliver light signals 64 ₁ for training as shown in FIG. Then the master station 63 has requested the transmission of optical signals for training with respect to the second slave station 61 _2, the optical signal 64 ₂ for training the second slave station 61 ₂ is that in response thereto Will be sent. The same applies hereinafter. In this way, the master station 63 communicates with each of the slave stations 61 attempting communication.
By requesting the transmission of optical signals for training from _{1 to} 61 _N in order, all the slave stations 61 that can currently communicate are detected, and individually from the slave station 61 in response to a request from the master station 63 side. Is trained for communication with each slave station 61 using the training optical signal 64 sent to the slave station 61.

In the example shown in FIG.
And the first to third slave stations 61₁~ 61_ThreeAre in the order of those requests
Optical signal 64 for training₁~ 64_ThreeSent out
The state is shown. In this figure, compared with FIG.
Light signal 64 for training ₁~ 64_ThreeThe time width of the tray
Data 31₁~ 31_ThreeAlthough it is longer than
This is training data 31₁~ 31_ThreeSame time width as
Can also be processed.

When the training period T ₁ ends, the operation period T ₂ starts. The master station 63 to slave station 61 ₁ to 61 _3, respectively in this operation period T ₂ and specified individually, will undergo a time division manner from their transmission of optical signals 64 ₁ to 64 ₃ individually.

FIG. 6 shows a state of the measurement information collection work performed by the master station for each slave station during the training period T ₁ when the system is started up. First, the above-mentioned CPU of the master station 63 is provided with a working RAM (not shown) (not shown).
The parameter n stored in the access memory) is set to “1”.
Initialized (step S101), and requests the transmission of the training data to the first slave station 61 ₁ (step S102). The master station 63 from the first slave station 61 ₁ This request
The transmission is performed by transmitting an optical signal in the direction opposite to the transmission using an optical fiber through which the optical signal 64 ₁ is transmitted.

First child station 61₁Is ready to communicate
If so, the first slave station 61₁Responds to this request by
Between the optical signal 6 and the predetermined training data.
4₁Will be sent out. First child station 61₁Does not exist
Or the first child station 61₁Something is wrong with
When communication is not possible due to the
₁Is not returned to the master station 63.

The master station 63 is whether the optical signal 64 ₁ is sent back to the predetermined time monitoring, when the optical signal 64 ₁ is sent back (step S103: Y), has been the back Measurement information is collected based on the training data as the optical signal 64 ₁ of the _first slave station 61 ₁ (step S104). Here, the collection of measurement information, using the inherent function of the 3R section 66 described in FIG. 2 and FIG. 3, the reception level of the optical signal 64 ₁ sent from the first slave station 61 ₁ In addition to obtaining a value for adjustment, a value for setting the generation timing of the received data is obtained. After first measurement information of the slave station 61 ₁ is obtained,
The CPU stores this in the storage unit 68 (step S105).

When the above processing is completed, the CPU
Counts up the value of the parameter n by "1" (step S106). Incidentally, when the optical signal 64 ₁ is not sent back within the specified time at step S103 and the flow proceeds directly to (N), also step S106. The CPU determines whether the rewritten value of the parameter n is larger than the number N of all the child stations 61 _{1 to} 61 _N that can be assumed (step S107). If it is larger (Y), the training period T ₁ Is completed, and a series of operations is terminated (END). In other cases (step S107: N), the process returns to step S102 to start collecting the measurement information for the next slave station (in this case, the second slave station 61 ₂ ). The same applies to the third slave station 61 ₃ or less.

[0045] Figure 7 is a flowchart showing a state of the data collect work master station makes to each slave station in the operation period T _2.
When the master station 63 determines that the first to third slave stations 61 _{1 to} 61 ₃ are in a communicable state during the training period T ₁ ,
As appropriate subsequent operation period T _2, specifying these slave stations 61 ₁ to slave station 61 ₃ to request the transmission of optical signals 64 ₁ to 64 _3. That is, the above-mentioned CPU determines the slave station 61 which receives this data (step S201), the data to be communicated originally with respect to the determined slave station (referred to as first slave station 61 _1.) Is requested (step S2).
02).

Upon receiving this request, the first slave station 61 ₁ transmits an optical signal 64 ₁ to the master station 63 as shown in FIG.

On the other hand, on the master station 63 side, step S202
In the requesting transmission of data, reads the measurement information about the first slave station 61 ₁ that the storage unit 68 (step S
203). And this basis, to set the generation timing such or capture settings and receive data of the amplification factor of the received data from which the timing of the waveform in the first slave station 61 for ₁ (step S204). And the first slave station 6
1 ₁ When the optical signal 64 ₁ is sent from, by performing the processing (step S205), 3 in the parent station 63 shown in FIG. 1
The received data 71 is output from the R unit 66 to the received data processing unit 72.

When the above processing is completed, the CPU restarts the processing from step S201 again. Figure 5 shows then the second slave station 61 ₂ sends data to the master station 63 in the example are required, the optical signal 64 ₂ is transmitted from the second slave station 61 ₂ to the master station 63 . At this time, the master station 63 is the second slave station 6
And after the setting of the reception level and the generation timing for the 1 _2, so that the received optical signal 64 ₂ is also performed in suitability. In the example shown in FIG. 5 so that the communication for the third slave station 61 ₃ after this takes place. Similarly, the first to third slave stations 61 ₁ to 61 ₁ until the operation period T ₂ ends.
61 ₃ sends the optical signal 64 _{1-64 3} to the parent station 63 is to continue from.

FIG. 8 shows a state of control on the master station side when communication is started again after communication between the master station and a predetermined slave station. Even if communication has been performed once, a new slave station 61 to be communicated may appear during that time. Therefore, the CPU performs an operation of detecting a new station to be communicated this time (step S301).
Then, when one new station (slave station 61) is detected (step S302: Y), measurement information is collected for the new station (step S303). The collected measurement information is stored in the storage unit 68 as described in step S105 (step S304).

When the measurement information of one slave station 61 whose measurement information has not been stored in the storage section 68 is thus collected, the CPU detects whether or not there is another new station with which communication is possible. (Step S301). As a result, when the next slave station 61 exists (step S3
02: Y), similar work of collecting and storing measurement information is performed (steps S303 and S304). The same applies hereinafter.

On the other hand, as a result of the detecting operation,
If the station has not been detected (step S30)
2: N), all measurement information of the slave stations 61 with which communication is currently possible
Has already been collected. So in this case
Is the operation period T described in FIG. _TwoEach slave station 61
The data collection work will be started (step
S305).

Modification

FIG. 9 shows a configuration of a master station of an optical transmission system according to a modification of the present invention. In this modification, the same parts as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted as appropriate. The master station 63A of this modification is 3R
It comprises a unit 66A and a reception data processing unit 72. 3
The R unit 66A has substantially the same function as the 3R unit 66 of the embodiment, but is divided into an optical / electrical converter 111 and a timing generator 112 in terms of circuit.

The optical-to-electrical conversion unit 111 includes a measurement unit 67A and a control unit 69A for inputting the optical signal 65 combined by the coupler 62 shown in FIG. 1, and data obtained as a result of measurement by the measurement unit 67A. A storage unit 68A for writing 76A is provided. Data 76A is data representing the measurement result of the reception level. In this modification as well, the storage section 68A is constituted by a nonvolatile memory in order to prevent unexpected loss of data. The data 77A stored in the storage section 68A is read out according to the slave station number information 74 supplied from the reception data processing section 72, and supplied to the control section 69A. Switching of writing of the data 76A to the storage unit 68A or reading of the data 77A is performed by the reception data processing unit 72 and the storage unit 68A.
A is performed by a read / write signal 75 supplied to A.

That is, the optical-electrical conversion unit 1 of this modified example
11 collects measurement information on each of the slave stations 61 _{1 to} 61 _N shown in FIG. 1 and stores data 76A regarding the obtained reception level in the storage unit 68A. At the time of operation, the data 77A corresponding to each of the slave stations 61 _{1 to} 61 _N is read out and set in the control unit 69A, so that the reception data 7 as an electric signal whose reception level has been corrected is obtained.
1A is sent to the timing generator 112.

The timing generator 112 receives the received data 7
1A, a measuring unit 67B and a control unit 69B, and data 76 obtained as a result of measurement by the measuring unit 67B.
A storage unit 68B for writing B is provided. Data 76B
Is data representing the generation timing of the received data. The storage unit 68B is also configured by a nonvolatile memory to prevent unexpected loss of data. The data 77B stored in the storage section 68B is read out according to the slave station number information 74 supplied from the reception data processing section 72, and supplied to the control section 69B. Storage unit 68B
Of the data 76B to the
The switching of the reading of B is similarly performed by the read / write signal 75 supplied from the reception data processing unit 72 to the storage unit 68B.

That is, the timing generator of this modification example
112 is each slave station 61 shown in FIG. ₁~ 61_Nabout
Collect measurement information and generate the resulting received data
Data 76B relating to timing is stored in the storage unit 68B.
Keep it. At the time of operation, each slave station 61₁~
61_NIs read from the data 77B corresponding to
Generation timing outside reception level by setting to B
The received data 71 as an electric signal corrected by
The data is sent to the video generation unit 112.

In the embodiment and the modified example, data (adjustment data) representing the measurement result is stored in the storage unit for each slave station, and such data is stored in a slave station in which such data is not stored in the storage unit. The adjustment data is measured or obtained based on the training data and stored in the storage unit. Due to recent advances in technology, it is no longer necessary to measure adjustment data each time a slave station performs data communication (see FIG. 11). However, for example, when the environmental temperature fluctuates greatly due to seasonal fluctuations, it may be necessary to rewrite the adjustment data even when the adjustment data has already been stored in the storage unit.

Therefore, conditions reflecting the age and temperature of the adjustment data stored in the storage unit, the temperature, the rate of occurrence of errors in the received data, and the like are set in advance, and when the conditions are satisfied, the adjustment data is taken again. This is also effective in improving data reliability. Such data updating may be performed for all the slave stations at the same time, or may be performed for each slave station each time a slave station satisfying the condition is generated.

[0060]

As described above, claims 1 to 3 are described.
According to the described invention, the adjustment data for adjusting the reception level and the adjustment data for adjusting the timing for reproducing the digital signal based on the training data sent from the transmitting apparatus during the training period are provided. Since the measured data is stored in the storage means, the adjustment data can be read out from the storage means in operation so as to correspond to the device on the transmission side and adjusted, and additional information for training can be obtained during operation. Waste of receiving each time can be eliminated, and efficient communication can be performed. Further, at the time of operation, it is unnecessary to provide a data processing area for measuring adjustment data, and in this sense, the load of communication processing is reduced.

According to the fourth aspect of the present invention, the training data is transmitted to the master station before the plurality of slave stations start communicating the data to be transmitted, and the master station receives the training data during the training period. The first and second adjustment data are acquired on the basis of the above, and are stored in a predetermined storage unit so as to shift to the operation period. There is no need to transmit additional information, and communication can be performed efficiently.

Further, according to the fifth aspect of the present invention, a confirmation step is provided to confirm whether or not the slave station stores the first and second adjustment data in the storage unit, and these adjustment data are stored. Since the predetermined training data is sent to the master station side for the slave station that is not performed,
In the case of the slave station in which the first and second adjustment data are already stored in the storage unit, the actual operation can be performed without further going through the training period, and the transmission period of the training data and the processing of the training data can be performed. Can be omitted.

According to the sixth aspect of the present invention, when the condition for rewriting these adjustment data is satisfied for the slave stations storing the first and second adjustment data in the storage section. Since the training data is sent again and the first and second adjustment data are rewritten to the latest data, the reliability of data reception can be improved.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram illustrating an optical receiving system according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration of a 3R unit according to the present embodiment.

FIG. 3 is various waveform diagrams showing waveforms of respective parts in FIG. 2;

FIG. 4 is a block diagram illustrating a specific configuration example of an equalization circuit.

FIG. 5 is a timing chart showing how an optical signal is transmitted from each slave station to a master station in the optical transmission system of the present embodiment.

6 is a flowchart master station showing a state of a measurement information collecting work performed for each slave station to the training period T ₁ of the time of start-up of the system in the Examples.

7 is a flowchart master station showing a state of a data collect work performed on each slave station to the operation period T ₂ in the Examples.

FIG. 8 is a flowchart showing a state of control on the master station side when communication is started again after communication between the master station and a predetermined slave station.

FIG. 9 is a block diagram illustrating a configuration of a master station of an optical transmission system according to a modification of the present invention.

FIG. 10 is a system configuration diagram showing a configuration of a conventional optical transmission system.

11 is a timing chart showing a state of transmission of each optical signal during system operation in the optical transmission system shown in FIG.

FIG. 12 is a system configuration diagram showing a configuration of another conventional optical transmission system in which data necessary for adjusting the level of an optical signal is stored.

[Explanation of symbols]

61 _{1 to} 61 _N First to Nth slave stations 62 Coupler 63 Master station 64 ₁ to 64 _N Optical signal 67, 67A, 67B Measurement section 68, 68A, 68B Storage section 69, 69A, 69B Control section 71 Received data 76 , 76A, 76B, 77,77A, 77B data T ₁ training period T ₂ operation period

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04B 10/04 10/06

Claims (6)

[Claims] 1. A reception level adjusting means for receiving an optical signal and adjusting the reception level to a predetermined signal level, and a timing for reproducing a digital signal transmitted based on the optical signal. Timing adjusting means for adjusting the transmission timing, and a transmission-side station based on training data transmitted from one or more devices on the transmission side during a training period prior to an operation period for transmitting data to be transmitted. Adjustment data measurement means for measuring the adjustment data used for adjustment by the reception level adjustment means and the generation timing adjustment means for each transmission, and the adjustment data measured by the adjustment data measurement means is stored for each transmission side device Storage means for reading out the adjustment data for the transmitting side device currently receiving from the storage means, Optical receiving apparatus characterized by comprising an optical signal receiving means for receiving the sent the incoming optical signal by adjusting means and generating a timing adjusting means from the device of the transmitting side. 2. The apparatus according to claim 1, wherein said reception level adjusting means and said generation timing adjusting means are optical signal reshaping means for regenerating an electric signal from the optical signal by linear amplification, and an optical signal or a signal converted into said electric signal. 2. An optical receiving apparatus according to claim 1, comprising: re-timing means for extracting a clock from the clock signal; and re-generating means for converting the signal level into a signal level for interfacing with a digital circuit in the next stage. . 3. An optical-to-electrical converter for converting a received optical signal into an electric signal, and an amplification factor adjuster for adjusting a signal level of the converted electric signal to a predetermined level. Wherein the generation timing adjustment means includes a clock extraction means for extracting a clock for reproduction based on a received optical signal, and a data identification means for generating data transmitted from the electric signal using the extracted clock. The optical receiving device according to claim 1, further comprising: 4. A training data transmitting step for sequentially transmitting predetermined training data to a plurality of slave stations to a master station, and when the training data is sequentially transmitted from the plurality of slave stations, the respective training data The first adjustment data for adjusting the reception level of the digital signal as data transmitted from the slave stations to a predetermined signal level and the timing for reproducing the digital signal are adjusted based on An adjustment data acquisition step of acquiring second adjustment data, and a storage step of, when the adjustment data is acquired for the plurality of slave stations, storing these adjustment data in a predetermined storage unit for each slave station; After transmitting the training data from the plurality of slave stations in the training data transmitting step, A data transmission operation start step for starting transmission of data to be transmitted to the plurality of slave stations; and in each of the slave stations transmitting data in the data transmission operation start step, First and second
Operating data receiving step of reading out the adjustment data from the storage unit and adjusting the reception level and the reproduction timing of the data received from the corresponding slave station based on the adjustment data. Light receiving method. 5. A first adjustment data for adjusting a reception level of a digital signal as data transmitted from a plurality of slave stations to receive data, and a reproduction of the digital signal. A step of confirming whether or not second adjustment data for adjusting the timing is stored in a predetermined storage unit; and in this confirmation step, the first and second adjustment data are stored in the storage unit. A training data transmitting step of transmitting predetermined training data to the master station side to a slave station having no training data; and a training data is sent from a slave station in which the first and second adjustment data are not stored in the storage unit. Adjusting data acquisition step of acquiring the first and second adjustment data based on the training data when Adjusting data obtaining step adjusting data storing step of storing the obtained first and second adjusting data in the storage unit; and a respective child storing the first and second adjusting data in the storing unit. Each time each slave station transmits data to the station, the first and second adjustment data of the corresponding slave station are read out from the storage unit, and the data received from the corresponding slave station based on these are read out. An operation data reception step of adjusting a reception level and a reproduction timing of the optical signal. 6. The training data is re-transmitted to a slave station storing the first and second adjustment data in the storage unit when predetermined conditions are satisfied, and new first and second adjustments are performed. Obtaining data; and when new first and second adjustment data are obtained, the first and second adjustment data for the slave station stored in the storage unit are stored in new first and second adjustment data. 6. The optical receiving method according to claim 4, further comprising: a latest data replacement step of replacing with the adjustment data.