JP2771071B2 - Transmission method via relay station - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission method for transmitting data via a plurality of relay stations connected by optical fiber cables.

[0002]

2. Description of the Related Art A transmission method via a relay station is based on a ring-shaped LAN (Local Area Network) in which nodes are connected in a ring.
etwork).

[0003] The conventional transmission method via the relay station is as follows.
A description will be given based on FIG. Relay stations 1, 2, 3 of each LAN
Are optical signal / electrical signal-converters (hereinafter abbreviated as OE converters) 4, 5, and 6, and OE converters 4, 5, and 6, respectively.
Computers (nodes) 7, 8, 9 of terminals connected to
OE converters 4 of the relay stations 1, 2, 3
5 and 6 are connected by optical fiber cables 10, 11, 12 and 13. The OE converters 4, 5, and 6 convert the input optical signals into electrical signals and output the electrical signals to the connected computers 7, 8, and 9, and further convert the converted electrical signals into optical signals to convert the optical signals into optical signals. The signals are output to OE converters 5 and 6 connected via cables 11, 12, and 13.

[0004]

However, according to the above-mentioned transmission method, the operating characteristics (rise,
(Falling characteristic), the transmission waveform is distorted, and there is a problem that it is difficult to add many relay stations, that is, many workstations.

For example, as shown in FIG. 5, in OE converters 5 and 6, the signal level changes from H (high level) to L.
(Low level) (2T in FIG. 5)
And the time (3T in FIG. 5) that changes from L to H is different, the signal lengths X and Z of the output signal x of the OE converter 4 and the output signal z of the OE converter 6 are different by a time 2T. Occurs. Thus, as the number of relay stations increases, the difference in signal length gradually increases, and an erroneous signal is transmitted.
The number of relay stations was limited.

Therefore, in order to increase the number of relay stations, a complicated frequency modulation circuit and phase modulation circuit are required, and depending on the transmission method, an optical fiber cable or conversion element having excellent characteristics must be used. There was a problem that it had to be an expensive network.

[0007] The present invention is to solve the above problems,
An object of the present invention is to provide a transmission method that can connect many relay stations at low cost without requiring a complicated circuit.

[0008]

SUMMARY OF THE INVENTION In order to solve the above problems, a transmission method via a relay station according to the present invention is an optical fiber transmission method.
A transmission method for transmitting data via a plurality of relay stations connected by a cable, wherein the data is modulated by the NRZ1 transmission method and transmitted via the optical fiber cable, and each of the relay stations receives an input signal. And outputs the result.

[0009]

According to the above configuration, the input signal is inverted at each relay station, so that even if there is a difference between the rising characteristic and the falling characteristic of the conversion element of the relay station, the time is offset, and the signal with less distortion is obtained. Is transmitted. Also NRZ
By using one transmission method, even if the signal is inverted, the transmission data is transmitted without any difference in meaning.

[0010]

An embodiment of the present invention will be described below with reference to the drawings. The same components as those in FIG. 4 of the conventional example are denoted by the same reference numerals, and description thereof will be omitted.

FIG. 1 is a block diagram of a LAN using a transmission method via a relay station according to the present invention, and each of the relay stations 1 ', 2', 3 '.
And inverters 14, 15, and 16 for inverting the output signals of the OE converters 4, 5, and 6, respectively.

The data transmission method is NRZ1 (Non-Zone).
Uses Return to Zero Change on 1). According to this transmission method, as shown in FIG. 3, every time the input data becomes 0, the signal is inverted and output.

The operation of the above configuration will be described with reference to the signal waveform diagram of FIG. . The output signal a of the OE converter 4 is inverted by the inverter 14, and the output signal b of the inverter 14 is input to the OE converter 5.
The signal is transmitted after rising at a delay of 3T and falling at a delay of 2T. The output signal c of the OE converter 5 is an inverter
The output signal d of the inverter 15 is O
The signal is input to the E converter 6, and the OE converter 6 falls with a delay of 2T and rises with a delay of 3T to be transmitted. The output signal e of the OE converter 6 is inverted by the inverter 16 and the output signal f is transmitted.

As can be seen from this signal waveform, the rise time and the fall time of the OE converter 5 and the OE converter 6 cancel each other, and the signal length A of the output signal a of the OE converter 4 and the output signal of the inverter 16 The signal length F of f is the same, so that a signal without distortion can be transmitted.

Further, by using the NRZ1 system, even if the signal is inverted, data can be transmitted without changing the meaning of the transmission data. In this way, a large number of relay stations can transmit a low-distortion signal without using complicated circuits and optical fiber cables and conversion elements with excellent characteristics.
Data can be transmitted via 1 ', 2', and 3 ', and a network can be formed at low cost.

[0016]

As described above, according to the present invention, since the signal is inverted at each relay station, even if there is a difference between the rising characteristic and the falling characteristic of the conversion element of the relay station, the time is not changed. Are canceled, and a signal with little distortion can be transmitted through a large number of relay stations. By using the NRZ1 transmission method, even if the signal is inverted, the transmission data can be transmitted without different meaning. Furthermore, the element for inverting the signal can be configured at a low cost, eliminating the need for using a complicated circuit or a fiber optic cable or a conversion element having excellent characteristics as in the past, and configuring a network at a low cost. .

[Brief description of the drawings]

FIG. 1 is a partial configuration diagram of a LAN using a transmission method via a relay station according to the present invention.

FIG. 2 is a main part signal waveform diagram of FIG. 1;

FIG. 3 is a modulation waveform diagram of the NRZ1 transmission method used in the transmission method via a relay station according to the present invention.

FIG. 4 illustrates a conventional L using transmission method via a relay station.
It is a partial block diagram of AN.

FIG. 5 is a main part signal waveform diagram of FIG. 4;

[Explanation of symbols]

 1 ', 2', 3 'Relay station 4,5,6 OE converter 7,8,9 Computer 10,11,12,13 Optical fiber cable 14,15,16 Inverter

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-64-16135 (JP, A) JP-A-3-205938 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H04B 10/00-10/28 H04L 25/00-25/66

Claims (1)

(57) [Claims] 1. A transmission method for transmitting data via a plurality of relay stations connected by an optical fiber cable, wherein the data is modulated by an NRZ1 transmission method and transmitted through the optical fiber cable. A transmission method via a relay station, wherein each relay station inverts the polarity of an input signal and outputs the inverted signal.