JPH10271069A - Optical repeater - Google Patents

Abstract

(57) [Summary] To transmit a Manchester code signal, an optical fiber system having twice the speed of transmitting a signal such as NRZ or NRZI must be used. This leads to an increase in cost. When an electric signal transmitted via an electric transmission line is a Manchester code signal, a code converter for converting the Manchester code signal into an NRZ or NRZI signal, and an electro-optical converter 12b. And a code converter 11b for converting the converted electric signal into a Manchester code signal. Even when the electric signal transmitted via the electric transmission line 30 is a Manchester code signal, the NRZ or NRZI signal The signal is transmitted by an optical fiber system used for transmission.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical repeater that converts an electric signal to be transmitted into an optical signal and converts the transmitted optical signal into an electric signal when the electric signal is transmitted using an optical fiber.

[0002]

2. Description of the Related Art In recent years, in the transmission of electric signals, optical fibers have been used for the purpose of measures against noise.
Since the construction of the optical fiber is troublesome, it is most efficient to use the optical fiber only for the main line as electricity.
For this reason, an optical repeater is used in a portion where an electric signal is transmitted using an optical fiber, and in the optical repeater provided on the transmission side, the electric signal is converted into an optical signal and the signal converted into the optical signal is converted into an optical fiber. After that, the transmitted optical signal is converted into an electric signal in an optical repeater provided on the receiving side, whereby the transmission of a desired electric signal using an optical fiber is performed. FIG. 2 is a diagram illustrating a configuration example of a transmission path using an optical fiber.

As shown in FIG. 2, optical repeaters 10A and 10B are provided at both ends of an optical fiber 20, and the optical fiber 20 and the electric transmission line 30 are connected via the optical repeaters 10A and 10B.

[0004]

FIG. 3 shows NRZ, NR
It is a figure showing an example of a signal of ZI and a Manchester code. As shown in FIG. 3, NRZ (Non-Return to Zer
o: code having no neutral state) is simply H = 1,
L = 0 and NRZI (Non-Return to Zero Inversi)
(on: code indicating the inversion state of the NRZ signal) is 1 when the signal does not change and becomes 0 when the signal changes. The signal of the Manchester code is a signal whose DUTY is 50%, and H = 1 and L = 0 in the preceding stage of the signal. The Manchester code signal is suitable for long-distance signal transmission because it does not include a DC component. However, as shown in FIG.
The frequency is doubled compared to signals such as NRZI and NRZI.

[0005] Therefore, in order to transmit a Manchester code signal, an optical fiber system having a speed twice that of transmitting an NRZ or NRZI signal must be used. There is a problem that it occurs. The present invention has been made in view of the above-mentioned problems of the conventional technology, and has as its object to provide an optical repeater that can transmit a Manchester code signal without increasing the cost. And

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a first electro-optical converter for converting an electric signal transmitted through an electric transmission line into an optical signal and sending the converted signal to an optical fiber. And a second electro-optical converter that converts an optical signal transmitted through the optical fiber into an electric signal;
The input of the electric signal transmitted through the electric transmission path to the first electro-optical converter and the transmission of the electric signal converted by the second electro-optical converter to the electric transmission path An optical repeater having a transmission switching unit for performing switching, when the electric signal transmitted through the electric transmission path is a Manchester code signal, converts the Manchester code signal into an NRZ or NRZI signal. A first code converter for converting the electric signal, and a second code converter for converting the electric signal converted in the second electro-optical converter into a Manchester code signal. And transmitting a Manchester code signal converted by the code converter to the electric transmission line.

Further, the electric signal converted by the second electro-optical converter is compared with a preset reference voltage, and a comparator for outputting a comparison result, and the comparator is activated by the comparison result output from the comparator. A mono-multi circuit for holding and outputting the comparison result for a predetermined time, wherein the transmission switching unit switches the operation based on the comparison result output from the mono-multi circuit. I do. In addition, the transmission switching unit is configured to output the Manchester code signal converted by the second code converter only when a voltage value of the electric signal converted by the second electro-optical conversion unit is higher than the reference voltage. Is transmitted to the electric transmission line.

(Operation) In the present invention configured as described above, in the first code converter, the Manchester code signal is converted into an NRZ or NRZI signal, and then transmitted through an optical fiber.
In the second code converter, the NRZ or NRZI signal transmitted by the optical fiber is converted into a Manchester code signal and transmitted to the electric transmission path, so that the electric signal transmitted through the electric transmission path is transmitted to the Manchester code. Even if it is a code signal,
The signal can be transmitted by an optical fiber system used to transmit NRZ or NRZI signals.
Further, when the electric signal converted in the second electro-optical converter is compared with a preset reference voltage, and the operation of the transmission switching unit is switched based on the comparison result, the squelch of the optical fiber is used. A circuit is formed, thereby suppressing noise generated when performing transmission.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing one embodiment of the optical repeater of the present invention. As shown in FIG. 1, a first code converter 11a converts an electric signal of a Manchester code into an NRZ or NRZI electric signal, and an optical fiber which converts an electric signal converted by the code converter 11a into an optical signal. A first electro-optical conversion unit 12a for transmitting the optical signal transmitted through the optical fiber 20 to an NRZ or NRZI electric signal;
b, a second code converter 11b for converting the electric signal converted by the electro-optical converter 12b into an electric signal of Manchester code, and a reference voltage set in advance by the electric signal converted by the electro-optical converter 12b. And a comparator 13 that outputs a comparison result, and a mono-multi circuit 14 that is activated by the comparison result output from the comparator 13 and holds and outputs the comparison result for a predetermined time
And an input of the electric signal transmitted through the electric transmission path 30 to the code converter 11a and an electric transmission path of the electric signal converted by the code converter 11b based on the comparison result output from the mono-multi circuit 14. And a transmission switching unit 15 for switching the transmission to the transmission unit 30.

The operation of transmitting a Manchester code signal on a transmission line using the optical repeater configured as described above will be described below. When an electric signal of the Manchester code to be transmitted is transmitted via the electric transmission line 30, the electric signal is input to the code converter 11a via the transmission switching unit 15. Then, in the code converter 11a, the input Manchester code electric signal is converted into an NRZ or NRZI electric signal and output. When an NRZ or NRZI electric signal is output from the code converter 11a, the output electric signal is input to the electro-optical converter 12a, and the input electric signal is converted into an optical signal in the electro-optical converter 12a. The light is sent to the optical fiber 20 and transmitted through the optical fiber 20.

On the other hand, when an optical signal is transmitted via the optical fiber 20, the transmitted optical signal is input to the electro-optical converter 12b, where the N
The signal is converted into an RZ or NRZI electric signal and output. When the electrical signal of NRZ or NRZI is output from the electro-optical converter 12b, the output electrical signal is input to the code converter 11b, where it is converted into a Manchester code electrical signal and transmitted to the transmission switching unit 15. Is entered. Here, the electro-optical converter 1
The electric signal output from 2b is also input to the comparator 13, where the electric signal is compared with a preset reference voltage and the comparison result is output.

The comparison result output from the comparator 13 is input to the mono-multi circuit 14 and
Is held and output for a predetermined time. Thereafter, the operation of the transmission switching unit 15 is switched based on the comparison result output from the mono-multi circuit 14, whereby the Manchester code electric signal output from the code converter 11b is transmitted to the electric transmission path 30,
The data is transmitted via the electric transmission path 30. Here, in the transmission switching unit 15, only when the voltage value of the electric signal output from the electro-optical conversion unit 12b is higher than the preset reference voltage by the comparator 13 and the mono-multi circuit 14, the code converter 11b Is switched so that the electric signal of the Manchester code output from is transmitted to the electric transmission line 30, so that noise generated at the time of transmission is suppressed.

[0013]

Since the present invention is constructed as described above, it has the following effects. 2. The first code converter according to claim 1, wherein when the electric signal transmitted via the electric transmission path is a Manchester code signal, the first code converter converts the Manchester code signal into an NRZ or NRZI signal. When,
Since a second code converter for converting the electric signal converted by the second electro-optical converter into a Manchester code signal is provided, the electric signal transmitted via the electric transmission path is a Manchester code signal. Even in such cases, the signal can be transmitted by an optical fiber system used for transmitting the NRZ or NRZI signal.

Thus, the Manchester code signal can be transmitted without increasing the cost. According to the second and third aspects, the electric signal converted in the second electro-optical converter is compared with a preset reference voltage, and based on the comparison result, the transmission switching unit is controlled. Since the operation is switched, noise generated at the time of transmission can be suppressed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of an optical repeater according to the present invention.

FIG. 2 is a diagram illustrating a configuration example of a transmission line using an optical fiber.

FIG. 3 is a diagram illustrating an example of signals of NRZ, NRZI, and Manchester code.

[Explanation of symbols]

 11a, 11b Code converter 12a, 12b Electric-optical conversion unit 13 Comparator 14 Mono-multi circuit 15 Transmission switching unit 20 Optical fiber 30 Electric transmission line

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI H04B 10/17 10/16

Claims (3)

[Claims] 1. A first electro-optical converter for converting an electric signal transmitted through an electric transmission line into an optical signal and sending the converted signal to an optical fiber, and converting the optical signal transmitted through the optical fiber into an electric signal. A second electro-optical converter that converts the signal into a signal, an input of the electric signal transmitted through the electric transmission path to the first electro-optical converter, and a conversion of the electric signal by the second electro-optical converter. An optical repeater having a transmission switching unit for switching the transmission of the electric signal to the electric transmission path, wherein the electric signal transmitted through the electric transmission path is a Manchester code signal. A first code converter for converting the Manchester code signal into an NRZ or NRZI signal, and a Manchester code signal converted by the second electro-optical converter. And a second code converter for converting the transmission switching unit, the light repeater, characterized by sending a signal of the converted Manchester code in the second code converter to the electrical transmission path. 2. The optical repeater according to claim 1, wherein the comparator compares the electric signal converted in the second electro-optical converter with a preset reference voltage, and outputs a comparison result. Activated by the comparison result output from the comparator,
A mono-multi circuit for holding and outputting the comparison result for a predetermined time, wherein the transmission switching unit switches the operation based on the comparison result output from the mono-multi circuit. Optical repeater. 3. The optical repeater according to claim 2, wherein the transmission switching unit performs the transmission only when a voltage value of the electric signal converted in the second electro-optical conversion unit is higher than the reference voltage. An optical repeater for transmitting a Manchester code signal converted by the second code converter to the electric transmission line.