JPS6198041A - Optical transceiver - Google Patents

Abstract

PURPOSE:To prevent the absence of a signal due to the insertion of a repeater by connecting an electrooptic and optoelectric converting device to an optical network, detecting the collision of a light signal on the optical network, and adding a preamble to a sent-out signal. CONSTITUTION:The transmit signal SD from a connecting device is S/P- converted 3 through an electric interface TIF1 and stored in an FIFO memory 4 while a preamble signal is added. The memory 4 is opened with the output of a timing generation part 2, P/S conversion 5 is performed, and electrooptic conversion 7 is also carried out through an optical interface OIF6, so that the signal is sent out. The transmit signal SD is applied from the TIF1 to a selector 13 as well and sent back to a receive data line. The input from the optical network is converted 8 optoelectrically and sent out to the receive data line RD. When a collision is detected 10-12 from the output of the OIF6, a signal is sent out to a display line CD. Consequently, the absence of a signal due to the insertion of a repeater is prevented to constitute a device which meets specific standards.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention is directed to a carrier detection method (CSMA/CD).
rier 5ense Multiple Acc
ess /Co-11ision Detection
The present invention relates to an optical transceiver that allows a device such as a data processing device having a coaxial network interface to be easily connected to an optical network that controls transmission of optical signals using the ) method.

[Conventional technology]

In networks using transmission lines such as coaxial cables, repeaters may be installed to compensate for losses in the transmission line, but the loss of signals due to such repeaters ranges from a few bits to more than 10 bits. This can be suppressed to . Also, insert a signal.

Since the loss due to branching is small, in a local area network, only two relay devices are required.
This is the largest system that can be configured. Therefore, by adding a relatively short preamble pattern (training pattern), data transmission can be performed.

In addition, a carrier detection method (in which transmission is started after confirming that no carrier exists on the transmission path, and if these transmissions occur simultaneously, it is detected as a transmission collision due to signal disturbance, etc., and retransmission processing is performed) C3MA/CD system) is relatively often adopted in local area networks and the like.

Optical networks using optical transmission lines are also known, and the loss caused by adding and branching an optical signal is greater than the loss in a coaxial network. This would require about 4 to 5 optical repeaters. Also, unlike repeating equipment in a coaxial network, an optical repeating device in an optical network requires pre-processing for electro-optical conversion, so no optical signal is sent out at all in the initial stage of startup. Therefore, a portion of the signal is lost each time it passes through an optical repeater.

[Problem that the invention seeks to solve]

It is desired to connect a device having an interface compliant with IEEE802.3 for existing coaxial networks to the above-mentioned optical network. IEEE
The 802.3 regulations specify access procedures, electrical characteristics, etc. For example, the maximum network delay time is set at 51.2 μs, and the packet format is as shown in Figure 3. As shown in , the 64-bit, 2-bit preamble P148-bit destination device address DA
, 48-bit self-device address SA, 16-bit data length information, and 8-bit n times length data DATA,
It consists of a 32-bit check code CRC, and the preamble P is "10101010" seven times and finally "
10101011'' is transmitted. Also, in the C3MA/CD system, the time from collision detection to display, the transmission of 32-bit or 48-bit jam patterns due to collision detection, etc. are determined.

When a device with such an IEEE 802.3 specified interface is connected to an optical network, not only the preamble P but also the addresses DA and SA may be lost due to signal loss in the optical repeater. be. In that case, there was a drawback that communication would not be possible.

Further, from the viewpoint of control, configuration, cost, reliability, etc., the optical network is configured to perform unidirectional communication, and constitutes a U-shaped network or an S-shaped network. When a U-shaped or S-shaped network is configured using optical transmission lines, the transmitted signal is folded back at the U-shaped or S-shaped folding part, and the signal is received and detected to monitor the transmission. Therefore, it is not possible to immediately detect the transmitted signal and monitor the transmission as in the case of a coaxial network.

Therefore, if a device that has an interface specified by rEEE802.3 is simply connected to an optical network, it will not comply with the specification, and there is a drawback that the device must be modified in order to connect to an optical network. Ta.

The present invention improves the above-mentioned drawbacks by compensating for bit loss due to passage through an optical repeater and reception detection delay of a transmitted signal, thereby modifying a device having an interface compliant with IEEE802, 3. The purpose is to make it possible to connect to an optical network.

[Means for solving problems]

The optical transceiver of the present invention is an optical transceiver for connecting a device having a coaxial network interface to an optical network that controls transmission of optical signals using a carrier detection method. That is, a conversion means for performing photoelectric conversion and electro-optical conversion, a collision detection means for optical signals on the optical network, a means for adding a preamble to an optical signal sent to the optical network, and a means for adding a preamble to an optical signal sent to the optical network, and a means for transmitting a transmission signal to a reception data line. It is equipped with means for folding back.

[Effect]

By adding a preamble with a number of bits greater than the number of bits lost in the optical repeater to the optical signal sent to the optical network, even the address part will not be lost even when multiple optical repeaters are installed. This eliminates the need for communication via optical networks. Also, since the transmitted signal is looped back to the received data line, IEEE80
A device having an interface compliant with 2.3 can be connected to an optical network without modification.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram of main parts of an embodiment of the present invention.
is an electrical interface unit (TIF) that complies with IEEE802.3 regulations, 2 is a timing generator (TG), 3 is a serial/parallel conversion/preamble generation unit (S/P), and 4 buffers the preamble pattern and transmission data. First-in, first-out memory (FI
FO), 5 is a parallel-to-serial converter (P/S), 6 is an optical interface unit (OIF), 7 is an electro-optical converter (Elo) that converts an electrical signal into an optical signal, and 8 is an electrical converter that converts an optical signal into an electrical signal. 9 is a reception clock extraction unit (CG) that extracts a clock from a received signal, 1
0 is the collision detection unit (CDT), 11 is Manchester (M
12 is a carrier detection unit (CAS), 13 is a selector (SEL)
). Also, PW is a power supply line, SG is a signal ground line, SD is a transmission data line, RD is a reception data line, and CD is a collision display line. ).

The optical signal from the optical network is converted into an electrical signal by the opto-electrical converter 8, and the electrical signal is sent to the reception clock extractor 9 through the optical interface 6. Collision detection unit 10
．． Manchester code rule detection unit 11. Carrier detection unit 12
and is added to the selector 13. The selector 13 is controlled by a timing signal from the timing generator 2,
At the time of transmission, the outside of the board is switched so that the signal from the optical interface section 6 is applied to the electrical interface section 1.

Further, the reception clock extraction section 9 has a known configuration for extracting clock components by means such as a resonance circuit, and the collision detection section 10 has a configuration for detecting a preamble pattern.
The preamble pattern is usually 8 bits 1010101
Since it is a repetition of 0'', it is possible to detect it with a simple logical configuration.Furthermore, the Manchester code rule detection unit 11 uses a Manchester code that sets l'' of the data to "10" and "0" to "01". It detects whether the received signal satisfies the rule, and "1" is 3 as Manchester code.
Since there are no more than 1 consecutive occurrences, it can be easily detected. This is because in a transmission collision state, optical signals are superimposed, resulting in an optical signal state that does not satisfy the Manchester coding rule. Therefore, by detecting the Manchester coding rule, it is possible to identify whether or not there is a transmission collision state. be able to. Further, the carrier detection section 12 detects whether or not an optical signal exists on the optical network.

The memory 4 is a buffer memory from which data written first is read out first, and has a configuration for performing 1-byte parallel processing. Note that serial processing is also possible, but the timing of writing and reading must be made faster. It also includes an output gate, and is controlled by a timing signal etc. from the timing generator 2, so that when the output gate is opened, successive data is output in parallel by one byte.

Further, the serial/parallel conversion/preamble generation section 3 generates a preamble pattern to be written into the memory 4 and converts the transmission data into parallel data, and detects a jam pattern sent from the connecting device and added via the electrical interface section 1. It has a function. The parallel-to-serial converter 5 is for converting parallel data read from the memory 4 into serial data, and the serially converted data is sent to the electro-optical converter 7 via the optical interface 6. The optical signal is added and converted into an optical signal, and the converted optical signal is sent to an optical network.

The timing generating section 2 is composed of a microprocessor, etc., and generates timing signals for controlling each section in synchronization with the signals from the electrical interface section 1. Also, the timing generating section 2 is configured to generate timing signals for controlling each section in synchronization with the signals from the electrical interface section 1. When the jam pattern is applied to the serial/parallel conversion/preamble generation section 3 via section 1, the jam pattern is detected and a detection signal is applied to the timing generation section 2, so that the timing generation section 2 has a simple pattern. A jam pattern is added to the optical interface section 6. This jam pattern is applied from the optical interface section 6 to the electro-optical conversion section 7, where it is converted into an optical signal and sent to the optical network.

When there is no transmission data on the transmission data line SD, the preamble patterns from the serial/parallel conversion/preamble generation section 3 are sequentially written into the memory 4 according to the timing signal from the timing generation section 2; Since it is closed, the optical interface unit 6 is controlled not to output. In addition, when there is no optical signal in the optical network, the carrier detection section 12 outputs a detection signal with no signal, and the electrical interface section 1
The vacancy is notified to the connected device via the reception data line RD.

When data is transferred from the connecting device to the transmission data line SD, this data is detected by the electrical interface section 1, and a clock is extracted to control the timing generation section 2, and the output gate of the memory 4 is opened. In addition, the transmission data is converted into parallel data by the serial/parallel conversion/preamble generation section 3 and added to the memory 4, and the selector 13 is controlled to switch so as to return the data to the electrical interface section 1, and the data is transferred onto the transmission data line SD. The transmitted data is looped back to the received data line RD. Therefore, the preamble pattern is first read out and sent out from the memory 4, and then the transmission data is read out and sent out. In addition, since carrier detection is always performed using the reception data line RD at position A, it is possible to detect that the self-connected device is transmitting by loopback by the selector 13 at the time of transmission. It is possible.

When there is no more transmission data on the transmission data line SD, a preamble pattern is stored in the memory 4, and all the transmission data is read out and sent out.

When there is no more transmission data in the memory 4, the output gate of the memory 4 is closed and the transmission of the packed preamble pattern is prevented. Further, the selector 13 is used to switch the path from the return state to the electrical interface section 1 to the path from the optical interface section 6 to the electrical interface section 1.

The transmission collision detection function in the optical network is activated from the start of preamble transmission as described above, and it is detected whether a transmission collision has occurred when the preamble pattern with a length equivalent to the delay of the transmission path has been transmitted. The carrier detection signal indicates that the transmission path is in use due to the start of transmission.
), when a preamble pattern is received from the optical network side by sending a preamble pattern (bl, if even one of the detection states of Manchester code rule normality (C) is missing, it is determined to be a transmission collision and the collision is displayed as a collision indication 'aCD'. The display pattern is sent out, and the return data is disturbed to notify the connected device of the occurrence of a transmission collision.The connected device sends out a jam pattern (collision emphasis signal) via the transmission data line SD, and this jam pattern determines the timing. The jam pattern is sent from the generation unit 2 to the optical ink face unit 6, converted into an optical signal by the electro-optical conversion unit 7, and sent to the optical network, thereby notifying that a transmission collision has occurred.

The optical signal from the optical network is converted into an electrical signal by the opto-electric conversion section 8, and is applied from the optical interface section 6 to the electrical interface section 1 via the selector 13, and from the electrical interface section 1 to the connecting device via the reception data line RD. will be transferred to.

FIG. 2 shows a flowchart of an embodiment of the present invention,
W OFF indicates that the output switch such as the output gate of the memory 4 is turned off. In this state, the preamble pattern P is loaded into the memory 4, and the loading of this preamble pattern P is completed with FULL.
In this case, it is determined whether or not terminal data is being received (data received from the connected device), and if the terminal data is not being received, the data is directly transferred to the terminal (connected device). That is, this is a case of receiving data from an optical network, and the data converted from the optical network by the electrical conversion section 8 is transferred from the optical interface section 6 to the electrical interface section 1 via the selector 13, and is connected to the reception data line RD. The received data is transferred to the terminal (connected device) via the .

In the case of terminal data reception, data is transmitted to the optical network, and the electrical interface section 1 pulls in a clock (CLK), and performs serial/parallel conversion on the data transferred via the electrical interface section 1. - Serial/parallel conversion S/P is performed in the preamble generation section 3, and it is determined whether or not it is a jam pattern. In the case of a jam pattern, the timing generator 2 is controlled to transmit the jam pattern.

If it is not a jam pattern, preamble pattern P
Transmission, writing data to memory FIFO, output switch/
ON SW ON control is performed, and parallel-serial conversion P/S in the parallel-serial conversion section 5 is performed. That is, memory 4
Output gates, etc. are turned on, and memory 4 is turned on.
The preamble pattern P loaded in advance is transmitted, data is written during that time, and when the transmission of the preamble pattern P is completed, the data is read and transmitted. Then, the parallel data read from the memory 4 is subjected to parallel-to-serial conversion by the parallel-to-serial conversion section 5 and is applied to the optical interface section 6.

Further, determination of the end of terminal data and collision detection are performed, and when the end of terminal data is identified, residual data is sent and preamble pattern P is loaded. That is, memory 4
In addition to transmitting the remaining data, the preamble pattern is loaded.

Collision detection is determined by Manchester code rule detection, carrier detection, preamble pattern detection, etc. When a collision is detected, a collision display is sent to the terminal side (connected device side), the output switch is turned OFF, and the memory is The preamble pattern P is loaded into the preamble pattern P.4.

In this way, since the preamble pattern P can be added to the beginning of the data, even if a part of the beginning is lost due to the optical repeater, the address part will not be lost, so communication can be performed. Become.

Therefore, the length of the preamble pattern P added to the optical transceiver is selected in consideration of the optical repeater, etc., and can be set to 1024 bits, for example. Further, the memory 4 for storing the preamble pattern P is a FIFO in the above-described embodiment, but it can also be constructed from a shift register, a ring memory, or the like.

〔Effect of the invention〕

As explained above, the present invention detects collisions between conversion means such as the opto-electrical converter 7 and the electro-optical converter 8 and optical signals on the optical network using carrier sense, preamble pattern detection, and Manchester code rule detection. a collision detection means for adding a preamble pattern using a memory 4 or the like; and a means for returning transmission data to a reception data line RD using a selector 13 or the like;
By adding a preamble pattern to the beginning and transmitting it to the optical network, even if a part of the signal at the beginning is lost in the optical repeater, the address part will not be lost. Also, when sending data to the optical network, U
Even if the optical transmission line is configured with an S-shaped or S-shaped optical transmission line, and the detection of the transmitted signal is delayed, by means of loopback,
Since the transmitted data is looped back and transferred to the connecting device, reception can be detected almost simultaneously with transmission. Therefore, for optical networks using carrier detection method,
This makes it possible to connect a connecting device having an interface compliant with the 02.3 standard in a plug-in format and perform data transmission.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a flowchart of the embodiment of the present invention, and FIG. 3 is an explanatory diagram of an example of a transmission format. 1 is an electrical interface section (TIF) compliant with IEEE802.3 regulations, 2 is a timing generation section (TG), 3 is a serial/parallel conversion and preamble ordering section (S/P), and 4 is a first-in/first-out memory (FIF).
O), 5 is a parallel-serial converter (P/S), 6 is an optical interface unit (OIF), 7 is an electro-optical converter (Elo),
8 is a photoelectric conversion unit (0/E), 9 is a reception clock extraction unit (CG), 10 is a collision detection unit (CDT), 1 is a Manchester code detection unit (MED), and 12 is a carrier detection unit (CAS). ), 13 is a selector (SEL).

Claims (1)

[Claims] In an optical transceiver for connecting a device having a coaxial network interface to an optical network that controls transmission of optical signals using a carrier detection method, a conversion means for mutually converting an optical signal and an electrical signal; An optical transceiver comprising: means for detecting a collision of optical signals on an optical network; means for adding a preamble to an optical signal sent to the optical network; and means for returning transmitted data to a received data line.