JPH04250728A - Optical transmitter - Google Patents

Abstract

PURPOSE:To send an auxiliary signal independently of a speed of a master signal by allowing an optical multiplexer/demultiplexer to apply optical wavelength multiplex to the main signal and the auxiliary signal subjected to optical conversion and to send the resulting signal. CONSTITUTION:A main signal of an optical pulse code modulation terminal station PCM 6 is converted into a coded mark inversion CMI signal. Then the electric main signal subjected to code conversion by an electrooptic conversion section 2 is converted into an optical signal and sent to an optical multiplexer demultiplexer 23 via an optical fiber 3. On the other hand, the auxiliary signal is converted into the CMI code the same as the main signal and the electric signal is converted into the optical signal and fed to the optical multiplexer demultiplexer 23 via the optical fiber 3. Thus, the main signal and the auxiliary signal are converted into the optical signal respectively in this way and subjected to optical wavelength multiplexing in the optical multiplexer demultiplexer 23 and the result is sent to an optical PCM terminal station 16. The main signal and the auxiliary signal are separated by the optical multiplexer demultiplexer 33 in the terminal station 16 by the reverse processing to above and they are sent respectively to interface sections 14, 15 via code conversion sections 11, 31.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical transmission device used, for example, in an optical pulse code modulation terminal station device.

0002

2. Description of the Related Art FIG. 2 is a block diagram showing a conventional optical transmission device. In the figure, numerals 1 and 11 are code conversion units for converting the code of a main signal from a main signal interface unit;
is an electro-optical converter that converts the main signal and auxiliary signal from one of the electrical signal and the optical signal to the other; 3 is the optical fiber cable; 4 and 14 are the above-mentioned main signal interface sections; 5 and 15
6 and 16 are optical pulse code modulation (hereinafter referred to as optical PCM) as an optical transmission device equipped with each of these circuits.
It is a terminal station.

Next, the operation will be explained. First, optical PC
The main signal of the M terminal station 6 passes through the main signal interface section 4 and is converted by the code conversion section 1 into, for example, coded mark inversion (hereinafter referred to as CMI) code. Next, the main signal of the electric signal is converted into an optical signal by the electro-optic converter 2 and then sent to the optical fiber 3. On the other hand, the auxiliary signal passes through the auxiliary signal interface section 5 and is transmitted by the code conversion section 1 with a violation (violation of the coding rules) applied to the code of the main signal. For example, in the case of a CMI code, the main signal "0" is converted to "01", but when a violation is applied, "0" becomes "10". The auxiliary signal superimposed on the main signal in the code converter 1 is converted from an electrical signal to an optical signal together with the main signal by an electro-optical converter 2, and then sent to the optical fiber 3. On the other hand, light P
In the CM terminal station 16, the electro-optical converter 12 converts the received optical signal into an electrical signal, and then the code converter 11 performs the reverse operation to separate it into a main signal and an auxiliary signal, which are then sent to the main signal interface section. 14 and the auxiliary signal interface section 15.

0004

[Problems to be Solved by the Invention] Since the conventional optical transmission equipment is configured as described above, for example, in the case of transmission using a CMI code, the transmission speed of the auxiliary signal depends on the speed of the main signal. The transmission speed is about 2% of the main signal,
For example, when the main signal speed is 1.5 Mb/s, the auxiliary signal can only be transmitted at a speed of 30 kb/s. As such a conventional optical transmission device, a similar technique is described in Japanese Patent Laid-Open No. 58-200642.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide an optical transmission device that can transmit an auxiliary signal without depending on the transmission speed of the main signal.

[0006]

[Means for Solving the Problems] An optical transmission device according to the present invention provides a first optical transmission device that converts a code-converted main signal into an optical signal.
and a second electro-optical converter that converts the code-converted auxiliary signal into an optical signal. The main signal is optically wavelength-multiplexed with an auxiliary signal after optical conversion, and then transmitted.

[0007]

[Operation] The optical multiplexer/demultiplexer of the present invention wavelength-multiplexes the optically converted main signal and the auxiliary signal and transmits the same, thereby making it possible to transmit the auxiliary signal without depending on the speed of the main signal.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, 1 is the first code conversion unit, 2 is the first
21 and 31 are second code conversion units for auxiliary signals connected to the auxiliary signal interface units 5 and 15;
22, 32 is a second electro-optical converter that converts the code-converted auxiliary signal from one of an electric signal and an optical signal to the other; 23;
Reference numeral 33 denotes an optical multiplexer/demultiplexer that wavelength-multiplexes the optically converted auxiliary signal into the optically converted main signal and outputs the optically converted main signal in each optical PCM terminal station 6, 16. Note that other components that are the same as those shown in FIG. 2 are designated by the same reference numerals, and redundant explanation thereof will be omitted.

Next, the operation will be explained. First, optical PC
The main signal of the M terminal station 6 is input to the code conversion section 1 via the main signal interface section 4, where it is converted into, for example, a CMI code. Next, the main signal of the electrical signal code-converted in the electro-optic converter 2 is converted into an optical signal, and then sent to the optical multiplexer/demultiplexer via the optical fiber 3. on the other hand,
The auxiliary signal passes through the auxiliary signal interface section 5 and is converted into, for example, a CMI code or the like by the code conversion section 21 in the same way as the main signal. Next, the electric signal is converted into an optical signal in the electro-optic converter 22, and further sent to the optical multiplexer/demultiplexer via the optical fiber 3. The main signal and auxiliary signal thus converted into optical signals are optically wavelength-multiplexed by the optical multiplexer/demultiplexer 7 and transmitted to the optical PCM terminal station 16. This light PC
In the M terminal station 16, the optical multiplexer/demultiplexer 17 separates the main signal and the auxiliary signal by the reverse procedure to that performed in the optical PCM terminal station 6, which basically has the same elements. The signal is transmitted to the main signal interface section 14 and the auxiliary signal interface section 15 via the conversion sections 11 and 31.

In the above embodiment, the case where the main signal and the auxiliary signal are transmitted between the optical PCM terminal stations 6 and 16 using the single-core optical fiber cable 3 was explained, but the main signal, clock, alarm, and monitoring By allocating light of different wavelengths to the auxiliary signals such as auxiliary signals, it is possible to perform wavelength multiplexing after each electro-optical conversion, and the same effect as in the above embodiment is achieved.

[0011]

[Effects of the Invention] As described above, according to the present invention, the first electro-optical converter converts the code-converted main signal into an optical signal, and the first electro-optical converter converts the code-converted auxiliary signal into an optical signal. A second electrical-optical converter is provided, and the optical multiplexer/demultiplexer optically wavelength-multiplexes the optically converted auxiliary signal onto the optically converted main signal and transmits the optically converted main signal so as not to depend on the speed of the optically converted main signal. With this configuration, there is an effect that the auxiliary signal can be transmitted between optical PCM terminal stations at high speed independent of the main signal.

[Brief explanation of the drawing]

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

FIG. 2 is a block diagram showing a conventional optical transmission device.

[Explanation of symbols]

1 First code conversion unit 2 First electro-optical converter 4 Main signal interface section 5 Auxiliary signal interface section 21 Second code conversion unit 22 Second electro-optical converter 23 Optical multiplexer/demultiplexer In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A first code conversion unit that converts the code of a main signal from a main signal interface unit; a first electro-optical conversion unit that converts the code-converted main signal into an optical signal; a second code conversion unit that converts the code of an auxiliary signal from an auxiliary signal interface unit independent of the signal interface unit; a second electro-optical conversion unit that converts the code-converted auxiliary signal into an optical signal; an optical multiplexer/demultiplexer that wavelength-multiplexes an auxiliary signal from the second electro-optic converter onto the main signal so as not to depend on the speed of the main signal from the first electro-optic converter and transmits the resultant signal; Optical transmission equipment equipped with