JP2000101669A - Parallel data transmission system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a parallel data transmission system without complicated control for synchronizing between respective transmitting pathes even in the case of fast transmission. SOLUTION: Each transmission path 51a to 5na is provided with a dividing means 21a to 2na dividing single data into m-pieces of slow data whose bit rate is 1/m, a transmission means 31a to 3na multiplexing each slow data to send to the transmitting path 51a to 5na, a receiving means separating each separated slow data and a composing means reproducing each separated data to be data before dividing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a parallel transmission system for transmitting a plurality of data in a transmission system to a reception system via a plurality of transmission lines connected in parallel between the transmission system and the reception system. It relates to a data transmission system.

[0002]

2. Description of the Related Art Since the performance of a single computer is limited, distributed processing by a plurality of computers is becoming mainstream in recent years. Along with this, there has been an increasing demand for faster and larger-capacity data transmission between computers. Therefore, there has been proposed a parallel data transmission system in which a plurality of data in a computer is transmitted as parallel data to a parallel transmission path including a plurality of transmission paths to perform data transmission. A problem in this parallel data transmission method is a difference in delay time between transmission paths, that is, a skew.

FIGS. 15A and 15B are timing charts for explaining a problem caused by skew. FIG. 15A shows a transmission clock TCK, FIG. 15B shows transmission data D1, FIG. 15C shows transmission data Dn, and FIG. Receive clock RCK, (e)
Indicates received data D1, and (f) indicates received data Dn. Here, n is an integer of 2 or more (hereinafter, referred to as “n”).
the same). Differences in the delay time when signals pass through each transmission line due to differences in the length of each transmission line connecting the transmission system and the reception system, and variations in the characteristics of the transceivers provided for each transmission line, etc. Occurs. In this case, as shown in FIG. 15, even if n transmission data D1 to Dn are transmitted from the transmission system in synchronization with a common transmission clock TCK, the reception system transmits n transmission data D1 to Dn. Skew occurs.

Usually, the rising edge of the clocks TCK and RCK is adjusted to the center of the data D1 to Dn,
1 to Dn are synchronized. However, the reception data D1 to D
If the deviation from the reception clock RCK at the center of each of n becomes equal to or more than 周期 cycle of the reception clock RCK, synchronization cannot be achieved with the common reception clock RCK. For example, as shown in FIGS. 15E and 15F, when “D11” of the reception data D1 is latched, “Dn0” of the reception data Dn is latched, and correct data is received by the reception system. Cannot read.

Therefore, a parallel data transmission system having means for correcting skew so that synchronization can be achieved between transmission lines has been proposed. FIG. 16 is a block diagram illustrating an example of the configuration of the skew correction unit. The skew correction unit shown in FIG. 16 is provided in the reception system, and is connected to the first synchronization unit 1011 connected to the transmission line 1001 that is the reference sequence, and to each of the other transmission lines 1002 to 100n. Second synchronization means 1012 to 101
n.

[0006] The first synchronization means 1011 is connected to the transmission line 1001.
Of the received data D1. Each of the second synchronization units 1012 to 101n is connected to the first synchronization unit 1
011 and the first synchronization means 10
When 11 synchronizes the received data D1 with the frame, the second synchronizers 1012 to 101n receive the synchronization information and synchronize the received data D2 to Dn of the transmission paths 1002 to 100n. . Thereby, the frame phases of all the received data D1 to Dn are aligned with the frame phase of the received data D1 of the reference sequence, so that the skew generated between the received data D1 to Dn is removed. This skew correction means is disclosed in
No. 37580.

[0007]

When a large amount of data is transmitted, the number of transmission lines 1001 to 100n becomes very large. For example, in the connection between nodes of a supercomputer, transmission lines 1001 to 100 of 1 Gbps are used.
n becomes several tens to several hundreds. In such a case, each transmission path 1
If a skew correction unit is provided for synchronization at 001 to 100n, it is necessary to monitor delay information between all the transmission lines 1001 to 100n and control the delay time of each of the transmission lines 1001 to 100n. In the Gbps class high-speed transmission, there is a problem that control becomes complicated.

The present invention has been made to solve such a problem, and an object of the present invention is to eliminate the need for complicated control for achieving synchronization between transmission lines even when high-speed transmission is performed. It is to provide a parallel data transmission system.

[0009]

In order to solve the above-mentioned object, the present invention provides a plurality of transmission lines in a transmission system via a plurality of transmission lines connected in parallel between a transmission system and a reception system. In the parallel data transmission system for transmitting the data of the data in parallel to the receiving system, the bit rate of one data in the transmitting system with respect to this data is set according to a predetermined division number m (m is an integer of 2 or more). A dividing means for dividing the data into 1 / m m pieces of low-speed data and outputting the divided data; a dividing means connected to the output side of the dividing means and connected to one end of one transmission path for multiplexing each low-speed data and transmitting Transmitting means for transmitting to the other end of the transmission path, receiving means for separating and outputting each low-speed data multiplexed by the transmitting means, and receiving means connected to the output side of the receiving means and separated by the receiving means To combine the low-speed data And a synthesizing means for reproducing and outputting data before division for each transmission path, and the number m of divisions of each division means is set such that a skew generated between the transmission paths is smaller than a period of each low-speed data. Each synthesizing means includes means for synchronizing at a common portion of each low-speed data by the first clock. According to a second aspect of the present invention, in the first aspect of the present invention, the number m of divisions of each dividing means is such that a difference between the central portion of each low speed data separated by each receiving means and the first clock is equal to each other. It is set to be less than 1/2 of the period of the low-speed data. According to a third aspect of the present invention, in the first or second aspect, each transmitting means is connected to an output side of the dividing means and converts each low-speed data into an optical signal having a different wavelength and outputs the converted signal. A light-to-light conversion means, and a wavelength multiplexing means connected to the output side of the light-to-light conversion means and connected to one end of the transmission path and coupling each optical signal to transmit the light signal to the transmission path,
Each receiving means is connected to the other end of the transmission line and separates each optical signal coupled by the wavelength multiplexing means for each wavelength, and outputs the separated optical signal. Photoelectric conversion means for converting each optical signal separated by the separation means into each low-speed data and outputting to the synthesizing means. According to a fourth aspect of the present invention, in the first or the second aspect of the present invention, each transmitting means is connected to an output side of the dividing means and transmits a carrier wave having a different frequency from each other and assigned to each low-speed data. Modulating means for outputting a plurality of modulated waves by modulating the signal; a frequency multiplexing means connected to the output side of the modulating means for frequency-multiplexing and outputting each modulated wave; and an output side of the frequency multiplexing means A light-to-optical conversion means for converting an output signal of the frequency multiplexing means into an optical signal and sending the signal to the transmission line, each receiving means being connected to the other end of the transmission line and Photoelectric conversion means for converting the electric signal into an electric signal and outputting the electric signal; frequency separating means connected to the output side of the photoelectric conversion means for separating the electric signal into respective modulated waves based on the frequency; Out of And a demodulating means for outputting being connected to the side and from the modulated wave combining means demodulates the respective low-speed data used for modulation of these modulated waves. According to a fifth aspect of the present invention, in the first aspect of the present invention, the second clock for synchronizing the respective division units is further divided by 1 / m to form a third clock. Output means, one of the transmitting means being connected to the output side of the frequency dividing means and multiplexing and transmitting the third clock with each low speed data output from the dividing means. The receiving means connected to the transmitting means via a transmission path separates the low-speed data multiplexed by the transmitting means from the third clock, and outputs the third clock as the first clock. Includes means. According to a sixth aspect of the present invention, there is provided a parallel data transmission system for transmitting a plurality of data in a transmission system to a reception system in parallel via a plurality of transmission paths connected in parallel between the transmission system and the reception system. In the transmission method, dividing means for dividing M (M is an integer of 2 or more) data in a transmission system into 2M low-speed data having a bit rate of 1/2 for these data and outputting the divided data. Transmitting means connected to the output side of the dividing means for outputting a first optical signal in which a part of each low-speed data is wavelength-multiplexed and a second optical signal in which the other part of each low-speed data is wavelength-multiplexed; A polarization multiplexing means connected to the output side of the means and connected to one end of one transmission path and converting the first and second optical signals into optical signals having mutually different polarization states and sending out to the transmission path; Light connected to the other end of the transmission line and transmitted from the polarization multiplexing means The first basis of the No. of the polarization state
And a polarization separation unit that separates and outputs the second optical signal,
Connected to the output side of the polarization splitting means and the first and second
Receiving means for converting the optical signal into low-speed data and outputting the low-speed data, and synthesizing means connected to the output side of the receiving means for synthesizing each low-speed data for each data before division and outputting the data. The period of the M data before division is set to be longer than ス of the skew generated between the transmission paths, and each synthesizing unit uses the first clock to generate a common part of each low-speed data. Includes means for synchronizing. Also,
The invention according to claim 7 is the invention according to claim 6,
The cycle of the M data before division is set such that the difference between the center of each low-speed data output from each receiving means and the first clock is less than half of the cycle of each low-speed data. I have. Further, the invention described in claim 8 is the invention according to claim 6 or 7.
In the described invention, each transmitting means is connected to the output side of the dividing means and converts each low-speed data into an optical signal having a different wavelength and outputs the same, and is connected to the output side of the electro-optical converting means. And a wavelength multiplexing means for generating a first and a second optical signal by coupling a part of the optical signal output from the electro-optical conversion means and another part, and outputting the generated first and second optical signals to the polarization multiplexing means. Is connected to the output side of the polarization splitting means and separates the first and second optical signals for each wavelength and outputs the separated signal; and is connected to the output side of the wavelength separating means and separated by the wavelength separating means. Photoelectric conversion means for converting each of the obtained optical signals into low-speed data and outputting to the synthesizing means. According to a ninth aspect of the present invention, in the sixth or seventh aspect, each transmitting means is connected to the output side of the dividing means and transmits a carrier having a different frequency from each other and assigned to each low-speed data. Modulating means for outputting a plurality of modulated waves by modulating a signal; a first electric signal connected to an output side of the modulating means and frequency-multiplexing a part of each modulated wave; Frequency multiplexing means for outputting the obtained second electric signal;
Electro-optical conversion means connected to the output side of the frequency multiplexing means and converting the first and second electric signals into first and second optical signals, respectively, and outputting the first and second optical signals to the polarization multiplexing means; Photoelectric conversion means connected to the output side of the polarization separation means for converting the first and second optical signals into first and second electric signals, respectively, and outputting the first and second electric signals; and connected to the output side of the photoelectric conversion means; Frequency separating means for separating the first and second electric signals into respective modulated waves based on the frequency and outputting the modulated signals; and a frequency separating means connected to the output side of the separating means and used for modulating these modulated waves from the respective modulated waves. Demodulating means for demodulating each low-speed data and outputting the demodulated data to the synthesizing means. According to a tenth aspect of the present invention, in the invention of any one of the sixth to ninth aspects, the second clock for synchronizing each of the dividing means is further divided by half to produce a third clock. Frequency dividing means for outputting, one of the transmitting means is connected to the output side of the frequency dividing means and wavelength-multiplexes a third clock together with a part of each low-speed data into a first optical signal. Output means, and receiving means connected to the transmitting means via a transmission line, converts the first optical signal into low-speed data and a third clock, and converts the third clock into a first clock. Output means. The invention according to claim 11 is the invention according to any one of claims 6 to 10, wherein
The first optical signal is an optical signal generated based on each one of the low-speed data obtained by dividing each data, and the second optical signal is an optical signal generated by dividing each data. This is an optical signal generated based on the other low-speed data. According to a twelfth aspect of the present invention, in any one of the sixth to eleventh aspects, the polarization multiplexing means includes a polarization rotator for rotating a polarization plane of the first or second optical signal. . According to a thirteenth aspect of the present invention, in the invention according to any one of the sixth to twelfth aspects, the polarization multiplexing means comprises:
And the polarization planes of the second optical signal are made orthogonal to each other. According to a fourteenth aspect of the present invention, in the thirteenth aspect, each transmission path is a polarization maintaining fiber for maintaining a polarization state of an incident optical signal.

[0010] The low-speed data obtained by dividing the data in the transmission system is transmitted to the reception system. As a result, the receiving system receives low-speed data having a longer cycle than the skew between the transmission paths, so that the transmission paths can be synchronized without correcting the skew. In addition, M data in the transmission system is 2M
The data is divided into low-speed data, divided into two, and wavelength-division multiplexed, and then converted into optical signals having different polarization states and transmitted. As a result, even when wavelength multiplexing on a transmission path is limited, the receiving system receives low-speed data having a longer cycle than the skew between the transmission paths.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIG. 1 is a block diagram showing an overall configuration of a first embodiment of a parallel data transmission system according to the present invention. This parallel data transmission system includes a transmission system A, a reception system B, and a parallel transmission line composed of n transmission lines 51a, 52a,..., 5na connecting the transmission system A and the reception system B. It is configured.

First, the configuration of the transmission system A will be described.
FIG. 2 is a block diagram illustrating a configuration of the transmission system A. The transmission system A includes a signal processing unit 1a, n division circuits (division means) 21a, 22a,..., 2na, and a frequency divider 2c.
And n wavelength multiplexing transmitters (transmitting means) 31a, 32
, 3na. The signal processing unit 1a includes n transmission data D1, D2,.
Are output in parallel and a transmission clock (second clock) TCK is output.

On the output side of the signal processing section 1a, n divided circuits 21a to 2na are connected in parallel. Each of the division circuits 21a to 2na transmits the transmission clock TCK.
One of the transmission data D1 to Dn output from the signal processing unit 1a is synchronized with the bit rate of 1 / m (m
Is an integer of 2 or more). For example, the transmission data D1 is divided into m pieces of low-speed data D1-1, D1-2,.
-M. Each of the dividing circuits 21a to 2na is constituted by a demultiplexer.

Further, a frequency divider 2c is connected to the output side of the signal processing section 1a. The frequency divider 2c divides the frequency of the transmission clock TCK for synchronizing the division circuits 21a to 2na, and divides the frequency by a frequency-divided transmission clock (third clock) TCK '.
Is output. Number of divisions of transmission data D1 to Dn by division circuits 21a to 2na (hereinafter referred to as division number)
Is set to m, the frequency divider 2c divides the transmission clock TCK by 1 / m.

The output side of each of the division circuits 21a to 2na is connected to a wavelength multiplexing transmitter 31a to 3na, respectively. The wavelength-division multiplexing transmitters 31a to 3na output the low-speed data D1-1 to D1-1 output from the division circuits 21a to 2na, respectively.
, Dn-1 to Dn-m are converted into multiplexed optical signals and transmitted to the transmission lines 51a to 5na. The wavelength multiplexing transmitter 31a is also connected to the output side of the frequency divider 2c, and outputs the low-speed data D1-1 to D1.
-M and the divided transmission clock TCK 'are converted into a multiplexed optical signal.

The transmission lines 51a to 5na are constituted by optical fibers. Optical signals having different wavelengths do not interfere with each other in one transmission line. Therefore, optical signals having different wavelengths can be transmitted through one transmission line. Therefore, even if the n pieces of transmission data D1 to Dn are divided into low-speed data, wavelength division multiplexing allows the n number of transmission paths 31a to 31n to remain unchanged.
3 na can be transmitted.

Here, the configuration and operation of the wavelength multiplex transmitter 31a will be described. FIG. 3 is a block diagram showing a configuration of the wavelength division multiplexing transmitter 31a. The wavelength division multiplexing transmitter 31a shown in FIG. 3 has laser diode driving circuits 111, 112,..., 11m, 11 to which the low-speed data D1-1 to D1-m and the frequency-divided transmission clock TCK 'are respectively input.
c and each of the laser diode driving circuits 111 to 11m, 1
1c connected to the respective laser diodes (hereinafter, L
D, 121), 122,..., 12m, 12
and a photocoupler 131 connected to the output sides of the LDs 121 to 12m and 12c and connected to one end of the transmission line 51a.

The LD driving circuits 111 to 11m are respectively
Each LD 121 is based on the low-speed data D1-1 to D1-m.
１２12 m. The LD drive circuit 11c drives the LD 12c based on the divided transmission clock TCK '. LDs 121 to 12m and 12c having different oscillation wavelengths are used. For example, 13
LDs having different oscillation wavelengths by several nm with a center wavelength of 00 nm are used. The photocoupler 131 is connected to each LD1
21 to 12m and 12c. The LD driving circuits 111 to 11m and 11c and the LD 121
12m and 12c constitute an electro-optical conversion means, and the photocoupler 131 constitutes a wavelength multiplexing means.

Based on the low-speed data D1-1 to D1-m and the frequency-divided transmission clock TCK ', the LDs 121 to 12m,
12c is driven, the low-speed data D1-1 to D1
-M and the divided transmission clock TCK 'are converted into optical signals having different wavelengths. Then, a plurality of optical signals having different wavelengths are combined into one optical signal by the photocoupler 131, and are incident on one end of the transmission line 51a.

FIG. 4 is a block diagram showing another configuration of the wavelength division multiplexing transmitter 31a. The wavelength-division multiplexing transmitter 31a shown in FIG. 4 includes modulators 141 and 141 to which the low-speed data D1-1 to D1-m and the divided transmission clock TCK 'are respectively input.
142,..., 14m, 14c,
Frequency multiplexing circuit 1 connected to the output side of 14m, 14c
32, an LD drive circuit 110 connected to the output side of the frequency multiplexing circuit 132, and an LD connected to the LD drive circuit 110 and connected to one end of the transmission line 51a.
120. The modulators 141 to 141
Modulation means is constituted by 14m and 14c, and electro-optical conversion means is constituted by LD drive circuit 110 and LD120.

To the modulators 141 to 14m and 14c, carrier waves having different frequencies assigned to the low-speed data D1-1 to D1-m and the divided transmission clock TCK 'are input from an oscillator (not shown). Each modulator 141
To 14m and 14c respectively convert these carrier waves into low-speed data D1-1 to D1-m and frequency-divided transmission clock TCK '.
, And outputs the result to the frequency multiplexing circuit 132. The frequency multiplexing circuit 132 frequency-multiplexes the modulated waves modulated by the modulators 141 to 14m and 14c, and
Give to 0. The LD driving circuit 110 is a frequency multiplexing circuit 13
Since the LD 120 is driven on the basis of the output of (2), the output of the frequency multiplexing circuit 132 is converted into one optical signal wavelength-multiplexed by the LD 120, and is incident on one end of the transmission line 51a.

As described above, the wavelength division multiplexing transmitter 31a may have any of the configurations shown in FIGS. In addition,
The wavelength division multiplexing transmitter 31a shown in FIGS. 3 and 4 uses an LD as an electro-optical conversion element as a light emitting element, but may use a light emitting diode instead. The other wavelength multiplex transmitters 32a to 3na have substantially the same configuration as the wavelength multiplex transmitter 31a. However, the other wavelength multiplexing transmitters 32a to 3na are the LD driving circuit 11c in FIG.
And the LD 12c or the modulator 14c in FIG.

Next, the configuration of the receiving system B will be described.
FIG. 5 is a block diagram showing the configuration of the receiving system B in FIG. The receiving system B includes n receivers (receiving means) 71
, 7na, n synthesizers (synthesizing means) 81a, 82a,..., 8na, and a multiplier 8c.
And a signal processing unit 9a.

Receivers 71a to 7na are connected to the other ends of the transmission lines 51a to 5na, respectively. Receiver 71a
To 7na respectively convert the optical signals multiplexed by the wavelength multiplexing transmitters 31a to 3na into the original low-speed data D1-1 to Dna.
.., Dn-1 to Dn-m and output. The receiver 71a connected to the wavelength-division multiplex transmitter 31a of the transmission system A via the transmission line 51a converts the optical signal multiplexed by the wavelength-division multiplex transmitter 31a into the original low-speed data D1-1 to D1-m. And divided transmission clock TC
K ′, and outputs the divided transmission clock TCK ′ as the divided reception clock (first clock) RCK ′.

Synthesis circuits 81a to 8na are connected to the output sides of the receivers 71a to 7na, respectively. further,
The divided reception clock RCK 'output from the receiver 71a is input to the combining circuits 81a to 8na. Each of the synthesizing circuits 81a to 8na outputs a divided reception clock RC.
Low-speed data D1-1 to D1-m,..., Dn-1 to Dn output from receivers 71a to 7na in synchronization with K '
m of n-m are combined and reproduced to receive data D1 to Dn whose bit rate is m times. Each of the synthesizing circuits 81 to 8na is configured by a multiplexer.

The output side of the receiver 71a is connected to a multiplier 8c. The multiplier 8c is provided with a frequency-divided reception clock RCK 'for synchronizing the respective synthesis circuits 81a to 8na.
Is multiplied by m, and a reception clock RCK obtained by reproducing the transmission clock TCK before frequency division is output. Synthesis circuit 8
1a to 8na and a signal processing unit 9 on the output side of the multiplier 8c.
a is connected, and n pieces of reception data D1 to Dn are input in parallel to the signal processing unit 9a, and a reception clock RCK is input.

Here, the configuration and operation of the receiver 71a will be described. FIG. 6 is a block diagram showing a configuration of the receiver 71a. The receiver 71a shown in FIG.
a, a photodiode (hereinafter abbreviated as PD) 161, 162,..., 1 connected to the output side of the wavelength filter 151.
6m, 16c and amplifier circuits 171, 172,..., 17 connected to the PDs 161 to 16m, 16c, respectively.
m, 17c.

The wavelength filter 151 includes the wavelength multiplex transmitter 3
The optical signal wavelength-multiplexed by 1a is converted into m +
This is separated into one optical signal and output. For example, AWG (Array Wave)
guide Grating) A filter is used. PD161-
Each of 16m and 16c converts an optical signal output from the wavelength filter 151 into an electric signal. The amplifier circuits 171 to 17n and 17c are respectively connected to PD1.
The outputs of 61 to 16 m and 16 c are amplified to logic levels. The wavelength filter 151 forms a wavelength separating unit, and the PDs 161 to 16m and 16c and the amplifying circuits 171 to 17n and 17c form a photoelectric conversion unit.

The optical signal transmitted to the other end of the transmission line 51a is separated by the wavelength filter 151 for each wavelength. The optical signals separated for each wavelength are PDs 161 to 16m, 16c
, Where it is photoelectrically converted and converted into low-speed data D1-1 to D1-m and frequency-divided transmission clock TCK 'before being electro-optically converted by the wavelength multiplexing transmitter 31a of the transmission system A. The signals are output from the amplifier circuits 171 to 17m.
However, the divided transmission clock TCK 'is output as the divided reception clock RCK'.

FIG. 7 is a block diagram showing another configuration of the receiver 71a. The receiver 71a shown in FIG. 7 includes a PD 160 connected to the other end of the transmission line 51a,
0, an amplifier circuit 170 connected to the
And a demodulator 18 connected to the output side of the frequency separation circuit 152.
, 18m, 18c.

The PD 160 converts an optical signal wavelength-multiplexed by the wavelength multiplex transmitter 31a into an electric signal. The amplification circuit 170 amplifies the output of the PD 160 to a logic level. The frequency separation circuit 152 separates the photoelectrically converted electric signal into m + 1 modulated waves based on the frequency. Demodulators 181 to 18m, 18
c is the low-speed data D used for modulating the modulated wave separated by the frequency separation circuit 152 from the modulated wave.
1-1 to D1-m and the frequency-divided transmission clock TCK 'are demodulated. The PD 160 and the amplifier circuit 170 constitute a photoelectric conversion unit, and the demodulators 181 to 18
Demodulation means is constituted by m and 18c.

The optical signal transmitted to the other end of the transmission path 51a is photoelectrically converted by the PD 160. The electric signal photoelectrically converted by the PD 160 is a bundle of modulated waves having different frequency components. By separating the electric signal for each frequency by the frequency separation circuit 152, each modulated wave can be separated. Since each modulated wave corresponds to the low-speed data D1-1 to D1-m and the divided transmission clock TCK 'in the transmission system A, the modulated waves are demodulated and output by the demodulators 181 to 18m and 18c. However, the divided transmission clock TC
K 'is output as the frequency-divided reception clock RCK'.

As described above, the receiver 71a may have any of the configurations shown in FIGS. The other receivers 72a to 7na have substantially the same configuration as the receiver 71a. However, the other wavelength multiplexing transmitters 72a to 7na
Does not include the PD 16c and the amplifier circuit 17c in FIG. 6 or the demodulator 18c in FIG.

Next, the operation of the parallel data transmission system shown in FIG. 1 will be described with reference to FIGS. 8A and 8B are timing charts of data and clocks in the transmission system A when the division number m of the division circuits 21a to 2na is m = 2, where FIG. 8A shows the transmission clock TCK, FIG. 8B shows the transmission data D1, and FIG. ) Is low-speed data D1-1, (d) is low-speed data D1-2, (e) is transmission data Dn, (f) is low-speed data Dn-1, (g) is low-speed data Dn-2, and (h) is The divided transmission clock TCK 'is shown. FIG. 9 is a timing chart of data and clocks in the receiving system B when m = 2.
(A) is a divided reception clock RCK ', (b) is low-speed data D1-1, (c) is low-speed data D1-2, (d) is low-speed data Dn-1, and (e) is low-speed data Dn-2. ,
(F) is received data D1, (g) is received data Dn,
(H) shows the reception clock RCK.

In the transmission system A, the signal processing section 1a separates n transmission data D1 to Dn into division circuits 21a to 2n, respectively.
and output in parallel to na. The signal processing unit 1a outputs the transmission clock TCK to each of the division circuits 21a to 2na.
At this time, as shown in FIG.
The rising edge of K is output in accordance with the center of each of the transmission data D1 to Dn.

Dividing circuit 21 to which transmission data D1 is input
8A shows the transmission data D1 shown in FIG. 8B in synchronization with the rise of the transmission clock TCK, as shown in FIGS. 8C and 8D, two low-speed data having a bit rate of 1/2. D1-1 and D1-2 are divided into wavelength division multiplexing transmitters 31a.
Output to Since the bit rate of each of the low-speed data D1-1 and D1-2 is 1/2 of the transmission data D1, the period of each of the low-speed data D1-1 and D1-2 is twice as long as the transmission data D1. Further, the frequency divider 2c frequency-divides the transmission clock TCK by よ う as shown in FIG. 8 (h), and outputs the frequency-divided transmission clock TCK 'to the wavelength division multiplexing transmitter 31a. At this time, the frequency divider 2c divides the frequency so that the rising edge of the frequency-divided transmission clock TCK 'comes to the center of the low-speed data D1-1 to Dn-2.

The wavelength multiplexing transmitter 31a receives the low-speed data D
1-1, D1-2 and the frequency-divided transmission clock TCK 'are converted into a multiplexed optical signal, incident on one end of the transmission line 51a, and transmitted to the receiving system B. Similarly, for the other channels, the transmission data D2 to Dn are divided, converted into multiplexed optical signals, and transmitted to the receiving system B via the transmission paths 52a to 5na.
The frequency-divided transmission clock TCK 'is transmitted only on the transmission line 51a.

In the receiving system B, the receiver 71a is connected to the transmission line 51.
The optical signal transmitted by a is separated into the original low-speed data D1-1 and D1-2 and the divided reception clock RCK 'shown in FIGS. 9A to 9C and output to the synthesis circuit 81a. Here, the divided reception clock RCK 'is the divided transmission clock T
Since it is the same as CK ', the divided reception clock RC
The cycle of K 'is the low-speed data D1-1, D1 in the receiving system.
Same as -2. The synthesis circuit 81a outputs the low-speed data D1
When -1 and D1-2 and the frequency-divided reception clock RCK 'are input, the low-speed data D1-1 and D1-2 are combined in accordance with the rise of the frequency-divided reception clock RCK'. As a result, the received data D1 that is the same as the transmitted data D1 as shown in FIG. 9F is reproduced and output to the signal processing unit 9a.

Similarly, for the other channels, the transmission path 5
The optical signals from 2a to 5na are converted to original low speed data D2-1 to D2-1.
After the conversion into n-2, the signals are combined and the signal processing unit 9a
Output to Further, the multiplier 8c outputs the divided reception clock RC.
K ′ is doubled, and a reception clock RCK identical to the transmission clock TCK as shown in FIG. 9H is output to the signal processing unit 9a.

In the case of the parallel data transmission system shown in FIG. 1, even if the transmission lines 51a to 5na have different lengths,
Due to variations in characteristics such as a to 3na and receivers 71a to 7na, as shown in FIGS.
Skew occurs between a to 5na. If the skew generated here is almost the same as in FIG. 15, the low-speed data D1-1 to D1-1
Since the cycle of n-2 is twice as long as the reception data D1 to Dn, the difference between the center of each of the low speed data D1-1 to Dn-2 and the rise of the divided reception clock RCK 'is the low speed data D1-1. .About.Dn-2. In this case, since the divided reception clock RCK 'can be synchronized with the common clock, there is no need to perform skew correction in the reception system B.

Further, when the skew increases due to a difference in the length of the transmission lines 51a to 5na, or when the transmission data D
Even when 1 to Dn are high speed and the influence of the skew is large, it is possible to eliminate the need to correct the skew by adjusting the number m of divisions of the division circuits 21a to 2na.

In general, the rise or fall of the clock is often synchronized with the center of the data, so that the description has been proceeded accordingly. However, in the parallel data transmission system shown in FIG. Data D1
It is not necessary to synchronize at the center of -1 to Dn-m. However, even in this case, the dividing circuits 21a to 21a to skew are smaller than the periods of the low-speed data D1-1 to Dn-m.
The division number m of 2na is set, and each low-speed data D1-1 to D1-1
It is necessary to be able to synchronize at a common portion of nm (for example, a common portion of D10, D11,..., Dn0, Dn1 in FIGS. 9B to 9E).

Here, the parallel data transmission method using optical transmission has been described, but this can also be performed by electric transmission. In this case, for example, the modulators 141 to 1 in FIG.
4m (14c) and what becomes the frequency multiplexing circuit 132 are used as the transmitter, and the frequency separation circuit 1 in FIG.
52 and demodulators 181 to 18m (18c) are used as a receiver, and a pair cable or a coaxial cable is used as a transmission path. The control method is basically the same as in the case of optical transmission.

(Second Embodiment) In the parallel data transmission method shown in FIG. 1, a plurality of data are once divided, multiplexed, and transmitted through one transmission line 51a to 5na. . However, when it is premised that a wavelength-multiplexed signal is originally transmitted on the transmission lines 51a to 5na for large-capacity transmission, there is a limit to the wavelength multiplexing. Can be difficult. The parallel data transmission method in such a case will be described.

In a second embodiment of the parallel data transmission system according to the present invention, a transmission system A, a reception system B, and a transmission system A
Transmission lines 51b, 52b,
.., 5 nb in parallel transmission lines. First, the transmission system A will be described. FIG. 10 is a block diagram illustrating a configuration of a transmission system A according to the second embodiment. FIG. 11 is a block diagram showing a configuration of the dividing unit 21b, the transmitting unit 31b, and the polarization multiplexing unit 41 in FIG. 10 and 11, the same or equivalent parts as those of the parallel data transmission system shown in FIG. 1 are denoted by the same reference numerals, and the description thereof will be omitted as appropriate.

As shown in FIG. 10, the transmission system A includes a signal processing unit 1b and n division units 21b, 22b,.
2nb, a frequency divider 2c, and n transmission means 31b and 32
b,..., 3nb and n polarization multiplexing means 41, 4
,..., 4n. The signal processing unit 1b includes n × M transmission data D1, D2,.
It outputs nM in parallel and outputs a transmission clock TCK. Here, M is an integer of 2 or more, and multiplexed signals of M data are transmitted to one transmission line 51b to 5nb, respectively.

On the output side of the signal processing section 1b, n dividing means 21b to 2nb are connected in parallel. Transmission data D1 to Dn are respectively provided to the division units 21b to 2nb.
M out of nM are input. Each dividing means 21b-2
nb indicates each of the input transmission data D1 to DnM in synchronization with the transmission clock TCK,
.., DnM-1, DnM, the two low-speed data D1-1, D1-2,.
-2. The dividing means 21b is arranged as shown in FIG.
As shown in FIG. 2, the circuit is composed of M divided circuits 211 to 21M having the same configuration as the divided circuit 21a in FIG. The same applies to the other dividing means 22b to 2nb.

As shown in FIG. 10, the dividing means 21b-2
Transmission means 31b to 3nb are connected to the output side of nb, respectively. The transmitting units 31b to 3nb respectively transmit the low-speed data D1- output from the dividing units 21b to 2nb.
It outputs a first optical signal obtained by wavelength-multiplexing a part of 1-DnM-2 and a second optical signal obtained by wavelength-multiplexing the other part of the low-speed data D1-1 through DnM-2.

The transmitting means 31b, as shown in FIG.
It is composed of two wavelength multiplex transmitters 311 and 312 having the same configuration as the wavelength multiplex transmitters 31a and 32a in FIG. One of the low-speed data D1-1, D2-1,..., DM-1 obtained by dividing each of the transmission data D1 to DM is input to one wavelength multiplexing transmitter 311. The cycle transmission clock TCK 'is input. The wavelength multiplexing transmitter 311 transmits each low-speed data D
A first optical signal obtained by wavelength-multiplexing 1-1 to DM-1 and the frequency-divided transmission clock TCK 'is output.

The other wavelength division multiplexing transmitter 312 includes:
The other low-speed data D1-2, D2-2,..., DM-2 obtained by dividing the transmission data D1 to DM, respectively.
The wavelength multiplexing transmitter 312 outputs a second optical signal obtained by wavelength multiplexing the low-speed data D1-2 to DM-2. An optical signal having a constant polarization plane is output from the LD used for the electro-optical conversion of each of the wavelength multiplexing transmitters 311 and 312. Note that the wavelength multiplexing transmitters 311 and 312 are
In the case of the configuration similar to that of the wavelength multiplex transmitter 31a shown in FIG. 7, the electro-optical conversion means of the transmission means 31b is constituted by the electro-optical conversion means of the wavelength multiplex transmitters 311 and 312, respectively. Constitutes the wavelength multiplexing means of the transmitting means 31b.

When the WDM transmitters 311 and 312 have the same configuration as the WDM transmitter 31a shown in FIG. 4, the modulation means of the WDM transmitters 311 and 312 modulate the transmission means 31b. Means are constituted, and the frequency multiplexing circuit 1
The frequency multiplexing means of the transmitting means 31b is constituted by 32, and the electro-optical converting means of the transmitting means 31b is constituted by the electro-optical converting means of each of the wavelength multiplexing transmitters 311 and 312. Here, the first electric signal is obtained by frequency-multiplexing a plurality of modulated waves output from the modulating means of the wavelength multiplexing transmitter 311, and the plurality of modulated waves output from the modulating means of the wavelength multiplexing transmitter 312 are frequency-multiplexed. The multiplexed signal is referred to as a second electric signal. These first and second electric signals are respectively
The signals are converted into first and second optical signals by the electro-optical conversion means of each of the wavelength multiplexing transmitters 311 and 312.

Since the divided transmission clock TCK 'is not input to the other transmitting means 32b to 3nb, the other transmitting means 3b
2b to 3nb are constituted by two wavelength multiplex transmitters having the same configuration as the wavelength multiplex transmitter 32a in FIG.

As shown in FIG. 10, the transmitting means 31b to 3b
Polarization multiplexing means 41, 42,..., 4n are respectively connected between the output side of nb and one ends of the transmission lines 51b to 5nb. Each of the polarization multiplexing units 41 to 4n is
The first and second optical signals output from each of 1b to 3nb are converted into optical signals having different polarization states from each other,
This is transmitted to the transmission lines 51b to 5nb. As shown in FIG. 11, the polarization multiplexing means 41 includes a polarization rotator 4 connected to the output side of the wavelength multiplexing transmitter 312 of the transmitting means 31b.
11 and a photocoupler 412 connected to the output side of each of the wavelength multiplexing transmitter 311 and the polarization rotator 411 of the transmission means 31b. Photo coupler 41
2 is connected to one end of the transmission line 51b.

The polarization rotator 41 adjusts the plane of polarization of the incident light by 90 degrees.
゜ It rotates, for example, a Faraday rotator is used. The photocoupler 412 is connected to the wavelength multiplex transmitter 31.
A first optical signal directly input from the first
1 and a second optical signal whose polarization plane has been rotated after passing through the first optical signal.

The wavelength division multiplexing transmitters 311,
From 312, first and second optical signals having a constant polarization plane are output. Assume that the first and second optical signals are both P-polarized. As shown in FIG. 12, the polarization plane of the second optical signal is rotated by 90 ° by the polarization rotator 411, becomes Q-polarized light, and is input to the photocoupler 412. On the other hand, since the first optical signal is directly input to the photocoupler 412, the polarization plane of the first optical signal is maintained. Therefore, the P-polarized first optical signal and the Q-polarized second optical signal are input to the photocoupler 412. The two optical signals whose polarization planes are orthogonal to each other are
The optical signal is coupled to one optical signal by 12 and is input to one end of the transmission line 51b.

The transmission lines 51b to 5nb have polarization maintaining fibers (polari) for maintaining the polarization state of the incident optical signal.
zation-maintaining fiber) is used. Even an ordinary single mode optical fiber can transmit two optical signals whose polarization planes are orthogonal to each other. However, when an external force is applied to the fiber or when the fiber is twisted, the polarization state is not maintained. Therefore, by using the polarization maintaining fiber, two optical signals can be transmitted to the receiving system B without changing the polarization state even in a situation where various external forces are applied to the transmission paths 51b to 5nb. Thus, two polarization states different from each other are obtained.
Since one optical signal can be transmitted through one transmission line, nM transmission data D1 to DnM are converted to low-speed data D1-1 to DnM.
Even if it is divided into -2, by changing the polarization state after wavelength multiplexing, n × M transmission data D1 to DnM can be transmitted as they are via the n transmission paths 51b to 5nb.

Next, the receiving system B will be described. FIG.
FIG. 9 is a block diagram illustrating a configuration of a receiving system B according to the second embodiment. FIG. 14 is a block diagram of the receiving unit 71 shown in FIG.
FIG. 6B is a block diagram illustrating a configuration of a combining unit b.
13 and 14, the same or equivalent parts as those of the parallel data transmission system shown in FIG. 1 are denoted by the same reference numerals, and the description thereof will be omitted as appropriate. As shown in FIG.
Are n polarization filters (polarization separation means) 61, 62,
.., 6n and n receiving means 71b, 72b,.
, 7nb and n combining means 81b, 82b,.
, 8nb, a multiplier 8c, and a signal processing unit 9b.

As shown in FIG. 13, the transmission lines 51b to 5n
Polarizing filters 61 to 6n are connected to the other end of b, respectively. Each of the polarizing filters 61 to 6n separates the optical signals from the transmission lines 51b to 5nb into first and second optical signals based on the plane of polarization and outputs the first and second optical signals. For the polarization filters 61 to 6n, for example, an optical fiber polarization beam splitter is used.

Receiving means 71b to 7nb are connected to the output sides of the polarization filters 61 to 6n, respectively. The receiving units 71b to 7nb are respectively transmitting units 31b to 3nb.
Are multiplexed with the original low-speed data D1-1 to D1-2,..., DnM-1 to DnM.
The output is converted to -2. Receiving means 71b
14, as shown in FIG. 14, the receivers 71a,
Two receivers 711, 71 each having the same configuration as 72a
2. One of the receivers 711 is the first
Is converted into one of the original low-speed data D1-1 to DM-1 and the divided transmission clock TCK ', and the divided transmission clock TCK' is output as the divided reception clock RCK '. The other receiver 712 converts the second optical signal into the other original low-speed data D1-2 to DM-2 and outputs the same.

When the receivers 711 and 712 have the same configuration as the receiver 71a shown in FIG.
11 and 712, receiving means 7
1b is constituted, and the receivers 711, 712
Each of the photoelectric conversion units constitutes a photoelectric conversion unit of the receiving unit 71b.

When the receivers 711 and 712 have the same configuration as the receiver 71a shown in FIG.
11 and 712, receiving means 7
1b, and the receivers 711, 712
The receiving means 71b is provided by each of the frequency separation circuits 152.
And the demodulation means of the receivers 711 and 712 constitute the demodulation means of the reception means 71b. Here, the first and second optical signals separated by the polarization filter 61 are respectively received by the receivers 711 and 7.
12 are converted into first and second electric signals by the photoelectric conversion means 12 and the frequency separation circuit 15 of each of the receivers 711 and 712.
2, the signal is separated into a plurality of modulated waves based on the frequency, and the demodulation means of each of the receivers 711 and 712 decodes the original low-speed data D1-
1 to DnM-2. Note that the other receiving means 7
2b to 7nb are configured by two receivers having the same configuration as the receiver 72a in FIG.

The combining units 81b to 8nb are connected to the output sides of the receiving units 71b to 7nb, respectively. Further, the frequency-divided reception clock RCK 'output from the reception unit 71b is input to the synthesis units 81b to 8nb. Each of the synthesizing units 81b to 8nb synchronizes with the frequency-divided reception clock RCK 'and outputs the low-speed data D1-1, D1-2,..., DnM output from the receiving units 71b to 7nb.
-1 and DnM-2 are combined to reproduce the received data D1 to DnM with a double bit rate.

The synthesizing means 81b, as shown in FIG.
.., 81M having the same configuration as the synthesizing circuit 81a in FIG. The combining circuit 811 is connected to the output side of each of the receivers 711 and 712 constituting the receiving means 71b so that the low-speed data D1-1 and D1-2 are input. Similarly, the other combining circuits 812 to 81M are connected to the respective output sides of the receivers 711 and 712. The same applies to the other combining means 82b to 8nb.

A multiplier 8c is connected to the output side of the receiving means 71b. An output side of the combining means 81b to 8nb and the multiplier 8c is connected to a signal processing unit 9b, and the signal processing unit 9b is connected to the n × M reception data D1 to Dn.
DnM is input in parallel, and the reception clock RC
K is input.

Next, the operation of the parallel data transmission system including the transmission system shown in FIG. 10 and the reception system shown in FIG. 13 will be described. In the transmission system A, n × M transmission data D1 to DnM are output in parallel from the signal processing unit 1b. Among them, M transmission data D1 to DM are input to the dividing means 21b, and the bit rate becomes 1 in synchronization with the transmission clock TCK.
/ 2 2M low-speed data D1-1, D1-2,...
, DM-1 and DM-2.

One of the M low-speed data D1-1 to DM-1 based on the M transmission data D1 to DM is transmitted by the transmitting unit 3.
The signal is converted into a first optical signal wavelength-multiplexed by 1b. Similarly, the other M low-speed data D1-2 to DM-2 based on the M transmission data D1 to DM are converted into the second optical signal by the transmission unit 31b. The polarization multiplexing unit 41 rotates the plane of polarization of the second optical signal so that the planes of polarization of the first and second optical signals are orthogonal to each other, and then makes the first and second optical signals enter one end of the transmission path 51b. Two optical signals whose polarization planes are orthogonal to each other do not interfere with each other in one transmission path 51b.

The optical signal transmitted to the receiving system B via the transmission line 51b is separated by the polarization filter 61 into a first optical signal and a second optical signal having different polarization states. The first and second optical signals are transmitted by the receiving means 71b to the low-speed data D1.
-1 to DM-2. Then, the low-speed data D1
-1 to DM-2 are synthesized by the synthesizing means 81b in synchronization with the reception frequency-divided clock RCK ', and the same reception data D1 as the transmission data D1 to DM before being divided in the transmission system A.
To DM are reproduced and output to the signal processing unit 9b. The same applies to other channels. That is, in the transmission system A, after the transmission data is once divided, it is converted into two optical signals having different polarization states, and the transmission paths 52b to 5nb
Is transmitted to the receiving system B. Then, in the receiving system B, received data is reproduced from the two optical signals transmitted from the transmitting system A.

As described above, in the parallel data transmission method shown in FIGS. 10 and 13, even when the wavelength multiplexing on the transmission lines 51b to 5nb is at the limit, two polarization states different from each other are obtained.
By converting the transmission data into one optical signal and transmitting it, each transmission data can be divided into two low-speed data having a bit rate of １ ／. Therefore, each of the transmission lines 51b to 5n
If the skew between b is less than twice the period of the transmission data D1 to DnM before division, the skew becomes smaller than the period of the low-speed data D1-1 to DnM-2 after division.
Synchronization can be achieved with a common clock RCK '. Therefore, the parallel data method shown in FIGS. 10 and 13 is particularly effective when the period of the transmission data D1 to DnM before division can be set to 1/2 to 1 times the skew. You don't have to.

The difference between the center of each of the low-speed data D1-1 to DnM-2 output from each of the receiving means 71b to 7nb and the received frequency-divided clock RCK 'is the same as the low-speed data D1-
NM so that it is less than 1/2 of the period of 1 to DnM-2.
The period of the transmission data D1 to DnM of the book may be set.

[0070]

As described above, according to the present invention, the low-speed data obtained by dividing the data in the transmission system is transmitted to the reception system. As a result, the receiving system receives low-speed data having a longer cycle than the skew between the transmission paths, so that the transmission paths can be synchronized without correcting the skew. Therefore, even when high-speed transmission is performed, synchronization can be achieved between the transmission paths without performing complicated control. Also, by multiplexing and transmitting low-speed data obtained by division, large-capacity transmission can be performed on a limited transmission path. According to the second aspect of the present invention, the number of divisions m of the dividing means is set so that the difference between the central portion of the low-speed data transmitted to the receiving system and the first clock is less than 1/2 cycle. Accordingly, it is possible to synchronize between the transmission paths without correcting the skew generated between the transmission paths.

According to the third and fourth aspects of the present invention, since the transmitting means and the receiving means include means for converting an electric signal and an optical signal, optical transmission can be realized. This enables data transmission with a larger capacity than electric transmission.
According to the fifth aspect of the present invention, the second clock for synchronizing the dividing means is divided and transmitted to the receiving system, and the synthesizing means is synchronized using the frequency. Thus, the second clock and the clock generated from the second clock can be used for dividing the data and synthesizing the low-speed data, so that the loss of synchronization can be reduced.

Further, according to the invention of claim 6, M data in the transmission system is divided into 2M low-speed data, these are divided into two, and wavelength division multiplexed, and then converted into optical signals having different polarization states from each other. Convert and transmit. As a result, even when wavelength multiplexing on a transmission path is limited, the receiving system receives low-speed data having a longer cycle than the skew between the transmission paths. For this reason, it is possible to synchronize the transmission paths without correcting the skew. In the invention according to claim 7, the cycle of the M data before division is set so that the difference between the central portion of the low-speed data transmitted to the receiving system and the first clock is less than 1/2 cycle. By setting, it is possible to synchronize between the transmission paths without correcting the skew generated between the transmission paths.

According to the tenth aspect of the present invention, the second clock for synchronizing each of the dividing means is frequency-divided and transmitted to the receiving system, and the synthesizing means is synchronized using this frequency. The same effect as the invention described in Item 5 can be obtained. According to the twelfth aspect of the present invention, one of the first and second optical signals is rotated, so that one polarization rotator is used to obtain optical signals having different polarization states. Can be. In the invention according to claim 14,
Since the transmission path is formed using polarization maintaining fiber,
Even in a situation where various external forces are applied to the transmission path, the same effects as the inventions of claims 6 to 13 can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an overall configuration of a first embodiment of a parallel data transmission system according to the present invention.

FIG. 2 is a block diagram showing a configuration of a transmission system in FIG.

FIG. 3 is a block diagram illustrating a configuration of a wavelength division multiplexing transmitter.

FIG. 4 is a block diagram illustrating another configuration of the wavelength division multiplexing transmitter.

FIG. 5 is a block diagram showing a configuration of a receiving system in FIG. 1;

FIG. 6 is a block diagram illustrating a configuration of a receiver.

FIG. 7 is a block diagram showing another configuration of the receiver.

FIG. 8 is a timing chart of data and clocks in the transmission system when the number of divisions of the division circuit is m = 2.

FIG. 9 is a timing chart of data and clocks in the receiving system when the number of divisions of the division circuit is m = 2.

FIG. 10 is a block diagram showing a configuration of a transmission system according to a second embodiment of the parallel data transmission system according to the present invention.

11 is a block diagram showing a configuration of a dividing unit, a transmitting unit, and a polarization multiplexing unit in FIG.

FIG. 12 is a schematic diagram showing how a polarization plane is rotated by a polarization rotator.

FIG. 13 is a block diagram showing a configuration of a receiving system according to a second embodiment of the parallel data transmission system according to the present invention.

14 is a block diagram illustrating a configuration of a receiving unit and a combining unit in FIG.

FIG. 15 is a timing chart for explaining a problem caused by skew.

FIG. 16 is a block diagram illustrating an example of a configuration of a skew correction unit.

[Explanation of symbols]

1a, 1b, 9a, 9b ... signal processing unit, 2c ... frequency divider,
8c: multiplier, 21a to 2na: dividing circuit, 21b to 2
nb: division means, 31a to 3na: wavelength multiplex transmitter, 3
1b to 3nb: transmission means, 41 to 4n: polarization multiplexing means,
51a to 5na, 51b to 5nb ... transmission lines, 61 to 6n
... Polarizing filter, 71a-7na ... Receiver, 71b-7
nb: receiving means, 81a to 8na: combining circuit, 81b to
8nb: synthesis means, 110 to 11m, 11c: LD drive circuit, 120 to 12m, 12c: LD, 131: photocoupler, 132: frequency multiplexing circuit, 141 to 14m, 1
4c: modulator, 151: wavelength filter, 152: frequency separation circuit, 160 to 16m, 16c: PD, 170 to 1
7m, 17c: amplification circuit, 181 to 18m, 18c: demodulator, 411: polarization rotator, A: transmission system, B: reception system,
D1 to Dn, D1 to DnM ... transmission data, reception data,
D1-1 to Dn-m, D1-1 to DnM-2: low-speed data, RCK: reception clock, RCK ': divided reception clock, TCK: transmission clock, TCK': divided transmission clock.

Claims (14)

[Claims] 1. A parallel data transmission system for transmitting a plurality of data in a transmission system to a reception system in parallel via a plurality of transmission paths connected in parallel between a transmission system and a reception system. According to a predetermined division number m (m is an integer of 2 or more), one piece of the data in the transmission system is divided into m pieces of low-speed data having a bit rate of 1 / m with respect to this data. Dividing means for outputting, transmitting means connected to the output side of the dividing means and connected to one end of one of the transmission lines for multiplexing the low-speed data and transmitting the multiplexed data to the transmission line; Receiving means for separating and outputting each of the low-speed data multiplexed by the transmitting means, and each of the low-speed data connected to the output side of the receiving means and separated by the receiving means Synthesizing A synthesizing unit that reproduces and outputs the data before division for each of the transmission lines; and a division number m of each of the division units is such that a skew generated between the transmission lines is smaller than a period of the low-speed data. The parallel data transmission system, wherein each of the synthesizing units includes a unit that synchronizes at a common portion of the low-speed data with a first clock. 2. The low-speed data according to claim 1, wherein the number m of divisions of each of the low-speed data is a difference between a central portion of the low-speed data separated by the reception means and the first clock. A parallel data transmission system characterized in that the period is set to be less than half the period. 3. An electro-optical conversion unit according to claim 1, wherein each of the transmission units is connected to an output side of the division unit, and converts the low-speed data into optical signals having different wavelengths and outputs the optical signals. Wavelength multiplexing means connected to the output side of the light-to-light conversion means and connected to one end of the transmission line, for coupling the optical signals and transmitting the signal to the transmission line; Wavelength separating means connected to the other end of the path and separating the optical signals coupled by the wavelength multiplexing means for each wavelength, and outputting the separated signals; and connected to the output side of the wavelength separating means and provided by the wavelength separating means. A photoelectric conversion unit for converting each of the separated optical signals into the low-speed data and outputting the low-speed data to the synthesizing unit. 4. The transmission device according to claim 1, wherein each of the transmitting units is connected to an output side of the dividing unit and modulates a carrier having a different frequency from each other and assigned to each of the low-speed data, with each of the low-speed data. A modulating means for outputting a plurality of modulated waves; a frequency multiplexing means connected to an output side of the modulating means and frequency-multiplexing and outputting each of the modulated waves; and a frequency multiplexing means connected to an output side of the frequency multiplexing means. An electro-optical conversion unit connected to one end of a transmission line and converting an output signal of the frequency multiplexing unit into an optical signal and transmitting the optical signal to the transmission line, wherein each of the reception units is connected to the other end of the transmission line. A photoelectric conversion unit that converts the optical signal into an electric signal and outputs the electric signal; a frequency that is connected to an output side of the photoelectric conversion unit and that separates the electric signal into the respective modulated waves based on a frequency and outputs the modulated wave. Separating means, and demodulating means connected to the output side of the frequency separating means and demodulating the low-speed data used for modulating these modulated waves from the modulated waves and outputting the demodulated low-speed data to the synthesizing means. A parallel data transmission system characterized by the following. 5. The frequency dividing means according to claim 1, further comprising a frequency dividing means for dividing a second clock for synchronizing each of said dividing means by 1 / m and outputting it as a third clock. One of the transmitting units includes a unit connected to an output side of the frequency dividing unit and multiplexing and transmitting the third clock together with the low-speed data output from the dividing unit; The transmitting means and the receiving means connected via the transmission line separate the low-speed data multiplexed by the transmitting means from the third clock and separate the third clock into the first clock. A parallel data transmission method, comprising means for outputting the clock as a clock signal. 6. A parallel data transmission system for transmitting a plurality of data in the transmission system to the reception system in parallel via a plurality of transmission paths connected in parallel between the transmission system and the reception system. The M (M is an integer of 2 or more) pieces of data in the transmission system is converted into 2M bits having a bit rate of 1/2 with respect to these data.
Dividing means for dividing the low-speed data into a plurality of low-speed data and outputting the first optical signal connected to the output side of the dividing means and wavelength-multiplexing a part of each of the low-speed data; Transmitting means for outputting a multiplexed second optical signal; connected to an output side of the transmitting means and connected to one end of one of the transmission lines, and polarizing the first and second optical signals with each other. A polarization multiplexing unit that converts the optical signal into an optical signal having a different state and sends the optical signal to the transmission line; Polarization separating means for separating and outputting the second optical signal; receiving means connected to the output side of the polarization separating means for converting the first and second optical signals into the low-speed data and outputting the low-speed data; Connected to the output side of this receiving means And synthesizing means for synthesizing each of the low-speed data for each of the data before division and outputting the data, for each of the transmission paths, wherein the cycle of the M data before division occurs between the transmission paths. The parallel data transmission method, wherein the skew is set to be longer than ス, and each of the synthesizing means includes means for synchronizing a common portion of each of the low-speed data with a first clock. 7. The apparatus according to claim 6, wherein the cycle of the M data before division is such that a difference between a central portion of each of the low-speed data output from each of the receiving units and the first clock is equal to each of the low-speed data. A parallel data transmission method characterized by being set to be less than 1/2 of a data period. 8. An electro-optical conversion unit according to claim 6, wherein each of the transmission units is connected to an output side of the division unit, and converts the low-speed data into optical signals having different wavelengths and outputs the optical signals. A part of the optical signal connected to the output side of the light-to-light conversion means and another part of the light signal output from the light-to-light conversion means are respectively coupled to generate the first and second light signals to generate the polarization multiplexed light. Wavelength multiplexing means for outputting to the means, each of the receiving means is connected to the output side of the polarization separation means, and separates the first and second optical signals for each wavelength and outputs the wavelength separation means; A photoelectric conversion unit connected to an output side of the wavelength separation unit and converting the optical signals separated by the wavelength separation unit into the low-speed data and outputting the low-speed data to the synthesis unit. Average Data transmission system. 9. The low-speed data according to claim 6, wherein each of the transmitting means is connected to an output side of the dividing means and modulates a carrier having a different frequency from each other and assigned to each of the low-speed data by each of the low-speed data. A modulating means for outputting a plurality of modulating waves, a first electric signal connected to the output side of the modulating means and frequency-multiplexing a part of each of the modulating waves and frequency-multiplexing another part of each of the modulating waves; Frequency multiplexing means for outputting the first electric signal and the second electric signal, and converting the first and second electric signals into the first and second optical signals, respectively. An electro-optical converter for outputting to a multiplexing unit, wherein each of the receiving units is connected to an output side of the polarization splitting unit and converts the first and second optical signals into the first and second electric signals, respectively. Convert and output Frequency conversion means connected to the output side of the photoelectric conversion means for separating the first and second electric signals into the respective modulated waves based on frequencies and outputting the modulated waves; And a demodulation means connected to a side of the apparatus and demodulating the low-speed data used for modulating the modulated waves from the modulated waves and outputting the demodulated data to the synthesizing means. 10. The frequency dividing means according to claim 6, further comprising a frequency dividing means for dividing the second clock for synchronizing each of said dividing means by １ ／ and outputting it as a third clock. One of the transmitting means is connected to the output side of the frequency dividing means and wavelength-multiplexes the third clock together with a part of the low-speed data and outputs the multiplexed signal as the first optical signal. The transmitting means and the receiving means connected via the transmission path convert the first optical signal into the low-speed data and the third clock to convert the third clock. A parallel data transmission system comprising means for outputting the first clock. 11. The optical signal according to claim 6, wherein the first optical signal is an optical signal generated based on each one of the low-speed data obtained by dividing each of the data. The parallel data transmission method, wherein the second optical signal is an optical signal generated based on each of the other low-speed data obtained by dividing each of the data. 12. The parallel data transmission according to claim 6, wherein the polarization multiplexing unit includes a polarization rotator for rotating a polarization plane of the first or second optical signal. method. 13. The parallel data transmission method according to claim 6, wherein the polarization multiplexing unit makes the polarization planes of the first and second optical signals orthogonal to each other. 14. The parallel data transmission method according to claim 13, wherein each of the transmission paths is a polarization maintaining fiber that maintains a polarization state of an incident optical signal.