JPS6010837A - Data transmitting system in repeater - Google Patents

Abstract

PURPOSE:To simplify the repeater and to attain inexpensive cost by inverting the polarity of a data signal, converting a collision detecting signal into a consecutive high level signal and then converting it into an optical signal so as to transmit the signal. CONSTITUTION:A data signal Da inputted to a data signal input terminal td becomes a signal Db whose polarity is inverted by an inverter 11 and fed to one input terminal of an OR circuit 12. The collision detecting signal Sa inputted to a collision detecting signal input terminal ts is inverted for the polarity at an inverter 13, becomes a consecutive H level signal Sc at a collision signal detecting circuit 14 and is fed to the other input of the OR circuit 12 and to a control circuit 15. An output of the OR circuit 12 is fed to a re-clock circuit 16, where only the data signal Da is subject to re-clock and converted into an optical signal. Further, the collision detecting signal Sc is converted into the optical signal as it is. The optical signal is fed to an optical directional coupler 19, from which the signal is transmitted to a repeater 1' through an optical fiber 20. Thus, the discrimination of both the signals after transmission is attained easily in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a data transmission system in a relay device (remote repeater) jζ used in a CSMA/CD local area network.

[Technical background of the invention]

Conventionally, in this type of relay device, as shown in FIG. 4, two repeaters 1 are connected to each other via a transmission path.
, 1', and these repeaters 1,
transceiver 3, which inputs and outputs signals to and from 1′, respectively;
3', and when a data signal flowing through one coaxial cable 4 is received by the transceiver 3, it is transmitted to the repeater 1 through the transceiver cable 5, and then this data signal is transmitted from the repeater 1 to the other side through the transmission path. The signal is transmitted to repeater 1'. The data signal transmitted to this repeater 1' is sent to a transceiver 3' through a transceiver cable 5', and is transmitted from the transceiver 3' into a coaxial cable 4'. Further, the data signal flowing in the coaxial cable 4' is transmitted into the coaxial cable 4 through a path opposite to that described above. here,
The transceiver cables 5, 5' are cables containing at least three signal lines.

Furthermore, if multiple data signals collide within one coaxial cable, for example 4, the transceiver 3 detects this and issues a collision detection signal, which is transmitted to the repeater 1 through the transceiver cable 5, and then The data signal is transmitted to the repeater 1' side through the transmission line, thereby rejecting input of the data signal from the transceiver 3' to the repeater 1'. The same applies when data signals collide within the other coaxial cable 4'.

The data signal used is a Manchester code whose data signal rate is fo bits/second (for example, 10 bits/second) and exhibits an H level when there is no signal, and the collision detection signal has a frequency of f. Hz (e.g. 10'Hz
) square wave signals are used, but when these signals are transmitted from repeater 1 to repeater 1', repeater 1' uses a signal to determine whether it is a data signal or a collision detection signal. However, in conventional relay devices of this type, data signals and collision detection signals are separated into separate signals using a transmission path consisting of multiple coaxial cables. The signals are transmitted through a wire, and both signals are discriminated by distinguishing the signal wires through which they are transmitted. Alternatively, a method has been adopted in which the transmission path is configured with an optical fiber, a signal in which both signals are multiplexed is converted into an optical signal, and the data signal and the collision detection signal are discriminated by this signal multiplexing. There is.

(Problems with the Background Art) By the way, when distinguishing between a data signal and a collision detection signal using signal lines as described above, not only four coaxial cables are required as a transmission path, but also four coaxial cables are required as transmission paths. However, coaxial cables have problems with noise resistance and are prone to accidents caused by lightning strikes, etc.] In addition, when multiplexing signals, optical fibers are used for the transmission path. Although the disadvantages of coaxial cables are improved in terms of noise resistance and prevention of lightning accidents,
In this case, since signals must be multiplexed, the structure of the relay device is complicated and expensive.

[Purpose of the invention]

Therefore, the present invention was made in order to effectively eliminate the drawbacks of the above-mentioned conventional devices of this type. An object of the present invention is to provide a data transmission system that enables discrimination between a data signal and a collision detection signal without causing an increase in cost or increase in cost.

[Summary of the Invention] In this invention, a data signal is transmitted after inverting its polarity and then converted into an optical signal, and a collision detection signal is converted into a continuous high (H) level signal and then converted into an optical signal. The above objectives are achieved by transmission.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 is a block diagram showing the configuration of the relay device main body 2 to which the data transmission method according to the present invention is applied. The overall configuration of the repeater is the same as that shown in Figure 1, and repeaters 1 and 1'
Since the internal configurations of the repeater 1' are the same, the components of repeater 1' are distinguished by adding a dash "1" to the reference code for the components of repeater 1, and the explanation for one repeater is the same as for the other. Omitted for repeaters.

The repeater 1 has an input terminal t, 1 for the data signal on the coaxial cable 4 transmitted from the transceiver 3, an input terminal t for the collision detection signal transmitted from the transceiver 3, and outputs a signal from the repeater 1 to the transceiver 3. and an output terminal t0. Note that since the interface between each terminal and the transceiver cable 5 is of a differential level, conversion between the signal level and the differential level is performed before and after signal input and output at each terminal.

Fig. 3 (a) J input to the data signal input terminal td.
A data signal Da consisting of a Manchester code with a signal speed fO bits/sec having a waveform shown in FIG.
As a result, as shown in FIG. 3 (b and l), the signal Db whose polarity is inverted is applied to one input terminal of the OR circuit 12. In addition, the collision detection signal is input to the terminals t and J. Figure 4(a) Frequency 'o)fz with the waveform shown
The collision signal Sa consisting of a square wave signal is transmitted to the inverter 13
The polarity is reversed at , and the signal Sb shown in Fig. 4 Φ) is obtained.
Next, in the collision signal detection circuit 14, a continuous H level signal Sc as shown in FIG. 4(C) is generated. This signal Sc is applied to the other input terminal of OR circuit 12 and control circuit 15. The output signal of the OR circuit 12 is applied to a reflock circuit 16 controlled by a control circuit 15, where only the data signal Db is reflocked and converted into an optical signal by an electro-optical converter (Elo) 17. Further, the collision detection signal Sc passes through the clock circuit 6 as it is, is applied to an electrical/optical converter (Elo) 17, and is converted into an optical signal. The optical signal is applied to an optical directional coupler (D, C) 19 through an optical fiber 18, and is transmitted to a repeater 1' through an optical fiber 2o forming a transmission path.

The optical signal transmitted from the repeater 1 to the peak 1' is applied to the optical-to-electrical converter (0/E) 22' through the optical directional coupler (D, C) 19' and the optical fiber 21', and is then sent to the electrical signal. If it is a data signal based on the signal Db shown in FIG. Data if @ D ((similar to data signal Da) as shown in Fig. 3 (C) is obtained. Also, the optical-to-electrical converter (0/E) 2
2' is the signal S in FIG. 4(C). If the collision detection signal is based on the collision detection circuit 26'
The output of the collision detection circuit 26' causes the signal switching circuit 24' to switch to the frequency f. The signal is switched to the oscillator 27' which generates a square wave signal of H2, and as a result, the frequency f is output from the signal switching circuit 24'. H2 square wave signal is output,
After this square wave signal passes through the reflock circuit 6', it is output to the output terminal t'. Therefore, the collision detection signal S as shown in FIG. 4(d)
It is output as d. This signal Sd is similar to the signal Sa shown in FIG. 4(a). The collision detection circuit 26' has two input terminals, one input terminal receives the output of the optical-to-electrical converter (0/E) 22', and the other input terminal receives the reflock circuit. 16' outputs are added to each. Also, a data signal input terminal td and an output terminal t. Each has a carrier detection circuit a′.

29' are connected, and their outputs are both connected to the control circuit 15.
' has been added to.

The above explanation has clarified the configuration of the relay device main body 2 shown in FIG. 2, and now its operation will be explained in more detail.

(1) When a data signal is input only to the data signal input terminal td.

When a data signal Da as shown in FIG. 3(a) is input to the terminal td, it is inverted by the inverter 11 and applied to the OR circuit 12. However, in this case, since no collision detection signal is input to the terminal ts, the inverter The output of 11 and the output of the OR circuit are the same. The data signal Db whose polarity has been inverted as shown in FIG. , C) 19 and the optical directional coupler (D, C) via the optical fiber 20
19', optical/electrical converter (0/E) 2
2' into an electrical signal, and then the inverter 23
' inverts the polarity. In this case, since no data signal is input to the data signal input terminal t/a, the output signal of the inverter n' is relocked by the reclock circuit 25' passing through the signal switching circuit 24', and becomes the input signal signal of the data signal input terminal t1. The waveform is reproduced and output from the output terminal t'o as a data signal DC as shown in FIG. 3(C). This output is detected by the carrier detection circuit 29', which operates the control circuit 15' to reject input to the data signal input terminal t/a.

(2) When the data signal is input only to the data signal input terminal t/a.

(Similar to the case of υ, except that the direction is reversed.

(3) A collision detection signal is input to the collision detection signal input terminal 115, but the data signal input terminal td and the collision detection signal input terminal 1. If not entered.

A collision detection signal S as shown in FIG. 4(a) is input to the input terminal tIs.
When the signal a is input, the collision signal detection circuit 14' generates the signal S shown in FIG.

is converted into an optical signal by an electric/optical converter (Elo) 17' via an OR circuit 12' and a reflock circuit 16', and then sent to an optical fiber 20 from an optical directional coupler (C, D) 19'.
Optical directional coupler (C, D) of repeater 1 via
19. This optical signal is sent to an optical-to-electrical converter (07
E) It is converted into an electrical signal at 22 and input to the collision detection circuit 26.

When the collision detection circuit 26 recognizes that the signal is a collision detection signal, the signal switching circuit 24 is switched to the oscillator 27 side. As a result, while the collision is detected by the collision detection circuit 26, the oscillator 27 generates a frequency f as shown in FIG. 4(d). A square wave signal Sd of H2 is output from the output terminal to. When the signal Sd is output from the output terminal t0, it is detected by the carrier detection circuit 29 and sent to the control circuit I.
5 operates, thereby rejecting the input of the D-- signal to the input terminal td.

(The collision detection signal is input to the input terminal 1s, but
When there is no input to input terminals t/d and 1/.

This is the same as case (3) except that the direction is reversed.

(5) When a data signal is input to the input terminal td and at the same time a collision detection signal is input to the input terminal 1/s.

The collision detection signal input to the input terminal t's is sent to the output terminal t in the same way as in case (3). ζ is output.

However, since the data signal is input to the input terminal td, the control circuit 15 does not perform the long sword rejection operation. Also, the data signal input to the input terminal td is (1)
As in the case of , the signal is output from the optical/electrical converter (0/E) 22', but the collision detection circuit detects that the signal is output from both the optical/electrical converter 22' and the reflock circuit 16'. 26' detects the signal switching circuit 24'.
is switched to the oscillator 27' side, and as a result, the frequency f. H2
A collision detection signal, which is a square wave signal, is also output from the output terminal t'o.

(6) When a data signal is output to the input terminal t'd and at the same time a collision detection signal is input to the input terminal ts.

This is the same as case (5) except that the direction is reversed.

(7) When a data signal is input to each of the input terminals td and t'd, and there is no input to the other input terminals.

The signals input to the input terminals td and t/a are (
In the same manner as in cases 1) and (2), the optical-to-electrical converter 2 is
2' and 22 and applied to collision detection circuits 26' and 26, but reflock circuit 16'.

Signals from 16 are also applied to collision detection circuits 26' and 26, respectively, to signal switching circuit 24'.

24 are switched to the oscillators 27' and 27, respectively, and therefore a collision detection signal which is a square wave signal with a frequency foH2 is output from the output terminal "O+'Q".

(8) When collision detection signals are input to input terminals ts and t/s, respectively.

Collision detection signals are output from output terminals i10 and to in the same manner as in (4) and (3) above. However, in this case, the control circuits 15' and 15 do not reject data input.

Referring now to Figure M5, the optical transmission section is shown. The optical directional couplers 19 and 19' used here are three-boat type with a branching ratio of 1:1. The optical signal output from the electrical/optical converter 17 is inputted from the terminal a of the optical directional coupler 19, outputs from the terminal only, passes through the optical fiber 20, and is sent to the terminal of the optical directional coupler 19'. input. Since the optical directional coupler 19' has a three-port configuration, terminals b→a
(output 1/2) and terminal b-+ ((output 1/2))
Of these, the optical signal output from terminal C is converted into an electrical signal by an optical-to-electrical converter 22'l.

Similarly, when an optical signal is output from the electrical/optical converter 17', it passes through the terminal B - + l) of the optical directional coupler 19', passes through the optical fiber 2o, and then reaches the terminal b of the optical directional coupler 19. −
*The signal passes through c and is converted into an electrical signal by the optical-to-electrical converter 22. In this case, even if optical signals are simultaneously output from the electrical/optical converters 17 and 17', there is no problem because the light is transmitted.

〔Effect of the invention〕

According to the data transmission method according to the present invention, the polarity of the data signal is inverted, and the collision detection signal is converted into a continuous H level signal and transmitted, so it is easy to distinguish between the two signals after transmission. Since the transmission path can be configured with a single optical fiber without using the conventional signal multiplexing transmission, the equipment can be simplified and inexpensive, and it also has excellent noise resistance and is less prone to lightning strikes. It is possible to obtain a relay device that is free from such risks.

[Brief explanation of drawings]

Fig. 1 is a block diagram of the entire relay device, Fig. 2 is a block diagram showing the configuration of the main body of the relay device to which the data transmission method according to the present invention is applied, and Figs. 3 (a) to (C) are waveform diagrams of data signals. , FIGS. 4(a) to 4(d) are waveform diagrams of collision detection signals, and FIG. 5 is an explanatory diagram of the optical transmission portion. ■, 1'...Repeater, 11.11', 13.13'
, 23°23'--Inverter, 12, 12'
=・OR circuit, 14, 14'...Collision signal detection circuit, 15.15'...Control circuit, 16°16', 2
5, 25'... Richronok circuit, 17.17'.
・Electrical/optical converter, 18.18', 20, 21.21
'...Optical fiber, 22.22'...Optical-to-electrical converter, 24.24'...Signal switching circuit, 26.26'...
Collision detection circuit, 27.27'...square wave oscillator, 28
．． 28', 29.29'...Carrier detection circuit

Claims (1)

[Claims] A data transmission system in a relay device comprising first and second repeaters configured to mutually transmit and receive a data signal consisting of a Manchester code with a signal speed fo bit/second and a collision detection signal consisting of a square wave signal with a frequency foH2. , the data signal is converted into a corresponding optical signal after inverting its polarity, and the collision detection signal is converted into a continuous high level signal and then converted into a corresponding optical signal, and these optical signals are converted into an optical signal. 1. A data transmission method in a relay device, characterized in that data is transmitted from one repeater to another repeater through a transmission path made of fiber.