JP2838454B2 - Optical transceiver - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical transceiver used for two-way communication of data via a pair of optical fiber cables in a network system for data communication.

[0002]

2. Description of the Related Art In general, in a network system for data communication, a pair of optical fiber cables is provided between transmission and reception points of the system, and optical transceivers are connected to both ends of the optical fiber cables. In some cases, data can be bidirectionally communicated in the form of an optical signal via an optical fiber cable.
The adoption of such a transmission method using an optical fiber cable allows long-distance transmission because the signal attenuation per unit length is smaller than when a coaxial cable or the like is used. This is because it has advantages such as being hardly affected by induction noise.

FIG. 3 shows an example in which a network system for data communication is constructed by connecting optical transceivers to both ends of a pair of optical fiber cables, in which L ₁ and L ₂ are shown. a pair of optical fiber cables, 1 ₀ a, 1 ₀ b is an optical transceiver which is connected to both ends of both optical fiber cable L _1, L _2, each of the optical transceiver 1 ₀ a, 1 ₀ b are both equal It has the configuration of Accordingly, here only to describe the configuration of the optical transceiver 1 ₀ a of the other hand (the left side in the figure).

[0004] The conventional optical transceiver 1 ₀ a, the pilot signal generating circuit 2a, a transmission control circuit 4a, an electrical / optical converter 6a, the optical / electrical converter 8a, the receiving control circuit 10a, a monitor circuit 12a, and alarm 14a.

[0005] The pilot signal generating circuit 2a is constant period T ₀ of the one that always generated a pulsed pilot signal s _1, the optical fiber cable L ₁ is the pilot signal s _1,
It is used to monitor the presence or absence of abnormality such as disconnection of L _2. Then, one cycle T of this pilot signal s _1
0 is set to be sufficiently longer than one bit period of the transmission data s ₂ to be transmitted in packet form.

[0006] The transmission control circuit 4a, and a transmission data s ₂ and a pilot signal s ₁ respectively input to the pilot signal s ₁ transmission data s ₂ in the case where the transmission data s ₂ and a pilot signal s ₁ coexist Selective output with priority, while transmission data
When s ₂ is not and outputs a pilot signal s ₁ alone.

The electrical / optical converter 6a converts the output from the transmission control circuit 4a to an optical signal and sends it to _one optical fiber cable L1, and the optical / electrical converter 8a connects to the other optical fiber. the optical signal transmitted from the cable L ₂ is intended for converting into an electric signal.

[0008] The reception control circuit 10a, the transmission data s except a pilot signal s ₁ from the output of the optical / electrical converter 8a
Only the reproduced received data is taken out from ₂ .

In the monitor circuit 12a, a predetermined threshold time Tsh (where Tsh> T ₀ ) is set in advance.
An alarm signal is output when no signal is output from the electric converter 8a for more than the threshold time Tsh, and is composed of, for example, a timer circuit or a retrigger / monomulti circuit. .

[0010] annunciator 14a is for notifying the abnormality of the optical fiber cable L ₂ by an alarm signal from the monitor circuit 12a, for example, composed of a LED or buzzer.

[0011] Next, the signal relay operation of the optical transceiver 1 ₀ a, 1 ₀ b in this network system will be described with reference to a timing chart shown in FIG.

[0012] (1) When optical fiber cables L _1, L ₂ are both normal example, whereas in the optical transceiver 1 ₀ a a (left side in FIG. 3), the optical transceiver 1 ₀ b of the other (right side in FIG. 3) If there is no transmission data s ₂ to be transmitted to the (until time t ₁ in FIG. 4)
The transmission control circuit 4a are constantly selects and outputs the pilot signal s ₁ from the pilot signal generating circuit 2a. The pilot signal s ₁ is converted into an optical signal by the electric / optical converter 6a, through one optical fiber cable L ₁ is input to the other optical transceiver 1 ₀ b. The optical transceiver 1 ₀ b of the optical / electrical converter 8b is an input optical signal into an electric signal to output. Therefore, from the photoelectric converter 8b, pilot signal s ₁ is output after being reproduced,
The pilot signal s ₁ is input to the reception control circuit 10b and the monitor circuit 12b. The reception control circuit 10b
When a signal input is a pilot signal s ₁ is not output the pilot signal s _1. Also, monitor circuit 1
2b, when the pilot signal s ₁ from the optical / electrical converter 8b is input, since there is no exceed the threshold time Tsh that no signal period is set in advance, the monitor circuit 12b
Does not output an alarm signal.

[0013] Next, when the transmission data s ₂ to be transmitted to the other optical transceiver 1 ₀ b occurs (between times t ₁ ~ time t ₂ in FIG. 4) from one of the optical transceiver 1 ₀ a is transmission control circuit 4a is the transmission data s ₂ and outputs the priority instead of the pilot signal s _1. This transmission data s ₂ is transmitted to the electrical / optical converter 6.
After being converted to an optical signal at a, through one optical fiber cable L ₁ is input to the other optical transceiver 1 ₀ b.
The optical transceiver 1 ₀ b of the optical / electrical converter 8b is an input optical signal into an electric signal to output. Therefore, from the photoelectric converter 8b, the transmission data s ₂ is output is reproduced as received data s _2, the received data s ₂ are input to the reception control circuit 10b and the monitor circuit 12b. Reception control circuit 10a outputs the received data s _2, etc., such as in FIG outside the workstation via a coaxial cable. The monitor circuit 12b, when the received data s ₂ from the optical / electrical converter 8a is input, since there is no exceed the threshold time Tsh that no signal period is set in advance, the monitor circuit 12b from likewise alarm signal s ₃ is not outputted.

[0014] The above operation, the other optical transceiver 1 ₀ b
Pilot signal to the one of the optical transceiver 1 ₀ a a
It is exactly the same when transmitting s ₁ and transmits data s _2.

[0015] (2) when the optical fiber cable for example L ₁ of one case where an abnormality is occurred, such as one of the optical fiber cable is broken is broken (time t ₃ or later), the other from one of the optical transceiver 1 ₀ a no longer send data to the optical transceiver 1 ₀ b.

[0016] In this case, the other optical transceiver 1 ₀ b
Respect of the monitor circuit 12b, since none of the pilot signals s ₁ and receive data s ₂ not input, so that the no-signal period exceeds a preset threshold time Tsh monitor circuit 12b. As a result, the monitor circuit 12b
Outputs an alarm signal, and the alarm 14b operates in response to the alarm signal. Thereby, it is possible to know abnormality of the optical fiber cable L ₁ in the other optical transceiver 1 ₀ b side.

[0017] Similarly, if the other optical fiber cable L ₂ was disconnected, in one optical transceiver 1 ₀ a side, since the alarm signal from the monitor circuit 12a to annunciator 14a is outputted, the optical fiber cable it is possible to know the abnormal occurrence of L _2.

[0018]

As described above, when an abnormality such as disconnection of one of the two optical fiber cables L ₁ and L ₂ , for example, L ₁ occurs on the way, one of the two optical fiber cables L ₁ and L _2. since the transceiver 1 ₀ a no longer send data to the other optical transceiver 1 ₀ b, in the optical transceiver 1 ₀ b on the other side, it is possible to know abnormality of the optical fiber cable L _1.

[0019] However, since the rest of the optical fiber cable L ₂ is normal, it is possible to transmit data to one of the optical transceiver 1 ₀ a from the other optical transceiver 1 ₀ b. Thus, whereas in the optical transceiver 1 ₀ a side can not know the occurrence of abnormality in the optical fiber cable L _1. That is, since the one optical transceiver 1 ₀ a pilot signal s ₁ or transmission data s ₂ from the other optical transceiver 1 ₀ b is inputted via the optical fiber cable L _2, the no-signal period monitor circuit 12a Does not exceed the preset threshold time Tsh, and therefore no alarm signal is output.

[0020] Data result, even though optical fiber cable L ₁ is abnormal, in order not to be able to know the abnormality occurs in one optical transceiver 1 ₀ a, with respect to the other optical transceiver 1 ₀ b Transmission will continue as it is. In particular, since it is often the optical transceiver 1 ₀ a, 1 ₀ b between the the distance from each other are separated, the mutual confirmation is not taken, readiness of repair actions for the abnormality may be insufficient. That is, even intended that sent the data from one of the optical transceiver 1 ₀ a side, the other optical transceiver 1
_{On the} 0b side, necessary data has not been received, which causes a problem that data exchange is not performed smoothly.

[0021]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and has two ends of a pair of optical fiber cables. When an error such as disconnection of one of the two optical fiber cables occurs when configuring a network system that performs
An abnormality occurrence can be simultaneously confirmed in both optical transceivers sandwiching the optical fiber cable, so that a countermeasure such as a repair process can be taken promptly.

Therefore, according to the present invention, transmission means for transmitting data and a pilot signal having a fixed period to each other in the form of an optical signal to one optical fiber cable and optical signals from the other optical fiber cable are transmitted. An optical transceiver comprising: a receiving unit that receives a data signal and a pilot signal; and a warning unit that outputs an alarm signal when a state in which these signals are absent continues for a predetermined threshold time longer than the predetermined period. Output prohibition means for prohibiting the transmission operation of the transmission means for a time longer than the threshold time in response to the alarm signal of (1).

[0023]

When a network system capable of two-way communication is constructed by connecting the optical transceivers according to the present invention to both ends of a pair of optical fiber cables, for example, one of the optical fiber cables is disconnected in the middle. Occurs, data cannot be transmitted from one optical transceiver to the other optical transceiver.

In this case, in the other optical transceiver of the transmission destination, the receiving means has a predetermined threshold time T
An alarm signal is output because no signal is input for more than sh. Thus, occurrence of an abnormality in the optical fiber cable can be known. In addition, in response to the alarm signal, the output prohibiting means prohibits the output of the transmission control circuit for a longer time than the threshold time Tsh. As a result, although the other fiber optic cable is normal,
In one optical transceiver, a non-signal period in which there is no input signal continues for a longer time than the threshold time Tsh. As a result, an alarm signal is output from the receiving means of the optical transceiver.

That is, if an abnormality such as a break occurs in one of the pair of optical fiber cables, an alarm signal is output from the receiving means of both optical transceivers sandwiching the optical fiber cable. At the same time, it is possible to know the occurrence of an abnormality in the optical fiber cable.

[0026]

FIG. 1 is a block diagram showing a case where a network system for data communication is constituted by using an optical transceiver according to the present invention. In FIG. 1, parts corresponding to those of the conventional example shown in FIG. Attach.

In FIG. 1, L ₁ and L ₂ are a pair of optical fiber cables, 1a and 1b are these optical fiber cables L
_An optical transceiver according to the present invention connected to both ends of L ₁ and L ₂ , wherein each of the optical transceivers 1 a and 1 b has the same configuration. So here on the other hand
Only the configuration of the optical transceiver 1a (left side in the figure) will be described.

The optical transceiver 1a comprises a pilot signal generating circuit 2a, a transmission control circuit 4a, an electric / optical converter 6
a, an optical / electrical converter 8a, a reception control circuit 10a, a monitor circuit 12a, and an annunciator 14a. However, since these configurations are the same as those of the conventional example, detailed description is omitted.

The optical transceiver 1a is characterized in that the transmission control circuit 4a responds to an alarm signal from the monitor circuit 12a.
Output prohibiting circuit 1 for prohibiting the output of the monitor circuit 12a for a longer time than the threshold time Tsh preset in the monitor circuit 12a.
6a.

In this example, the output prohibiting circuit 16a responds to an alarm signal from the monitor circuit 12a to output a pulse having a period of a half cycle T / 2 (> Tsh) longer than the threshold time Tsh. A burst signal generating circuit 18a for outputting a burst signal in a shape of a circle, and a burst circuit 20a for stopping the output of the transmission control circuit 4a for a low level period of half a cycle T / 2 of the burst signal from the burst signal generating circuit 18a. Consists of

Next, the signal relay operation of the optical transceivers 1a and 1b in this network system will be described with reference to FIG.
This will be described with reference to the timing chart shown in FIG.

(1) When both the optical fiber cables L ₁ and L ₂ are normal In this case, the pilot signal s ₁ or the pilot signal s ₁ is transmitted to each of the optical transceivers 1 a and 1 b via the optical fiber cables L ₁ and L _2. since the transmission data s ₂ is transmitted, the monitor circuit 12
No warning signal is output from a and 12b. The operation in this case is the same as that of the conventional optical transceiver, and the detailed description is omitted.

[0033] (2) when the optical fiber cable for example L ₁ of one case where an abnormality is generated, such as one L ₁ of the optical fiber cable is broken is broken, toward the one of the optical transceiver 1a to the other optical transceiver 1b Cannot send data.

In this case, the other optical transceiver 1b
Respect of the monitor circuit 12b, since none of the received data s ₁ and pilot signal s ₂ is not input, so that the no-signal period exceeds a preset threshold time Tsh monitor circuit 12b. As a result, the monitor circuit 12b
Outputs an alarm signal, and the alarm 14b operates in response to the alarm signal. Thereby, it is possible to know abnormality of the optical fiber cable L ₁ in the other optical transceiver 1b side.

In response to the alarm signal, the burst signal generation circuit 18b of the other optical transceiver 1b responds to the alarm signal as shown in FIG.
Long pulsed burst signal s ₃ having a duration of a half period T / 2 (> Tsh) is output than. Subsequently, the burst circuit 20b will only stop the output of the transmission control circuit 4b period of the half period T / 2 minutes of low level of the burst signal s _3.

As a result, from the transmission control circuit 4b of the other optical transceiver 1b, for example, as shown in FIG.
Even if the transmission data s ₂ Following pilot signal s ₁ is output, as shown in FIG. 2 (c), while the burst signal s ₃ period T / 2 (time t ₁ ~ time t ₂ of the low level ) What such signal will not be transmitted to the other optical fiber cable L _2.

Therefore, the other optical fiber cable L
Despite the fact that ₂ is normal, there is no signal input to one optical transceiver 1a for the above-described period T / 2.
The non-signal period T / 2 is longer (T.sub.T) than a threshold time Tsh preset in the monitor circuit 12a.
/ 2> Tsh), an alarm signal is output from the monitor circuit 12a, and in response to the alarm signal, the alarm 14a
Works. Thereby, one of the optical transceivers 1a
It is possible to know abnormality of the optical fiber cable L ₁ also in side.

[0038] That is, an abnormality in one of the optical fiber cable L ₁ occurs, will be able to know that both the optical transceiver 1a sandwiching the optical fiber cable L _1, at the same time occurrence of abnormality in 1b.

[0039] In the above description, the abnormality in one of the optical fiber cable L ₁ has been described as being generated, for the occurrence of abnormality in the other optical fiber cable L _2, the operation was essentially the same Thus, occurrence of abnormality can be known in both optical transceivers 1a and 1b.

[0040]

In the optical transceiver according to the present invention, when a network system is constructed using the optical transceiver, the optical fiber cable is sandwiched in response to occurrence of an abnormality such as disconnection of one of the optical fiber cables. Since the occurrence of the abnormality can be confirmed at the same time by both optical transceivers, it is possible to quickly take a measure such as a repair procedure. In addition, since it is possible to transmit data while checking for the occurrence of an abnormality in the optical fiber cable, excellent effects such as an increase in reliability of data communication can be achieved.

[Brief description of the drawings]

FIG. 1 is a block diagram when a network system for data communication is configured using an optical transceiver according to the present invention.

FIG. 2 is a timing chart for explaining the operation of the optical transceiver of FIG. 1;

FIG. 3 is a block diagram when a network system for data communication is configured using a conventional optical transceiver.

FIG. 4 is a timing chart for explaining the operation of the optical transceiver of FIG. 3;

[Explanation of symbols]

1a, 1b: optical transceiver, 2a, 2b: pilot signal generation circuit, 4a, 4b: transmission control circuit, 6a, 6b: electric /
Optical converters, 8a, 8b ... optical / electrical converters, 10a, 10b ...
Reception control circuit, 12a, 12b ... monitor circuit, 16a, 1
6b ... Output inhibit circuit.

Claims (2)

(57) [Claims] 1. A transmission for transmitting data and a pilot signal having a constant period in the form of an optical signal to one optical fiber cable, which is used for two-way communication via a pair of optical fiber cables. Means for receiving data and a pilot signal transmitted in the form of an optical signal from the other optical fiber cable, and alarming when the absence of these signals continues for a predetermined threshold time longer than the predetermined period. Receiving means for outputting a signal; and output inhibiting means for inhibiting a transmitting operation of the transmitting means for a time longer than the threshold time in response to an alarm signal from the receiving means. Optical transceiver. 2. The transmission means inputs a pilot signal generation circuit that constantly generates a pulsed pilot signal having a constant period T ₀ , transmission data and a pilot signal, and the transmission data and the pilot signal coexist. In this case, the transmission data is output in preference to the pilot signal,
A transmission control circuit that outputs a pilot signal when there is no transmission data; and an electrical / optical converter that converts an output from the transmission control circuit into an optical signal and sends the optical signal to one optical fiber cable. The means converts an optical signal transmitted from one of the optical fiber cables into an electrical signal and outputs the electrical signal, and extracts only received data from the output of the optical / electric converter except for a pilot signal. A reception control circuit;
The optical / electrical transducer signal output is the absence preset threshold time from Tsh (However, Tsh> T ₀₎ according in which and a monitor circuit for outputting an alarm signal when continued over Item 2. The optical transceiver according to Item 1.