JPH0795153A - Optical communication system - Google Patents

Abstract

PURPOSE:To obtain the optical communication system in which communication interruption resulting from interruption of a transmission line is decreased, a signal with a best reception state is selected and handled as a reception signal and communication of lots of data is implemented at a high speed by using plural light emitting sections or light receiving sections. CONSTITUTION:An optical modulator 4 applies optical modulation to a carrier based on an analog signal in an optical transmitter 102 and the light subject to optical modulation is sent through an optical fiber. A light emitting section 5 emits a light sent through the optical fiber into space. Light receiving sections 6-8 of an optical receiver 101 receive the emitted light and sends the light through an optical fiber. An optical demodulator 9 applies photoelectric conversion to the light sent through the optical fiber into an analog signal, which is detected by a signal detector 11 as a digital signal. A hit detection section detects a hit of the analog signal and a control section 12 controls the signal selection section based on the hit information and selects the detected digital signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical communication system, and more particularly to an optical communication system for performing optical communication through space by providing a plurality of transmitters or receivers and separating transmission lines into a plurality of transmission lines. The present invention relates to an optical communication system in which information transmission is continued by the remaining transmission lines even if one transmission line is blocked.

[0002]

2. Description of the Related Art In recent years, optical data communication technology has been used in the fields of terrestrial optical communication and space communication. In particular, laser technology has begun to be applied to optical data communication. Optical data communication in this field is mainly intended for long distance and large capacity communication. Since the optical data communication in this field uses the atmosphere as a communication path, there is a problem that the communication condition is deteriorated due to the strength of the optical signal depending on the weather conditions, and the optical signal is interrupted due to clouds etc., and the communication becomes impossible. was there.

Further, in recent years, optical data communication applying a laser technique has been performed for indoor data communication with a relatively short communication distance such as data communication between computers and data communication between computers and terminal devices. In optical data communication including this laser technology, a wide bandwidth can be secured in the optical data communication, so that high-speed data communication in the base band is possible.

Complete electrical insulation is obtained between the light emitting portion and the light receiving portion, and direct current transmission with a baseband waveform is possible. In the case of optical data communication, no electrical wiring is required between the light emitting section and the light receiving section. Optical data communication is strong against noise because it is not affected by electromagnetic waves. Such features are listed.

[0005]

However, there is a problem that the optical data communication is interrupted when the transmission line of the optical data communication is interrupted by a factor such as passage of a person or obstruction by animals and insects. It was Therefore, the present invention is
By using multiple light emitting units or light receiving units, it is possible to reduce communication interruptions due to interruption of the transmission path, select the signal with the best reception condition and treat it as a reception signal, and use high-speed optical data communication. , The challenge is to carry out a large amount of data communication.

[0006]

The invention according to claim 1 is
In order to solve the above problems, an optical transmitter that converts communication data into light and emits the light into space, and an optical receiver that converts the received light into communication data, and performs optical communication through the space In the communication system, the optical receiving device includes a light receiving unit that receives the light emitted from the transmitting device, an optical demodulator that photoelectrically converts the light received by the light receiving unit into an analog signal, and the optical demodulator. A signal detector that detects the converted analog signal into a digital signal, a signal selection unit that selects the digital signal detected by the detector, and a momentary interruption of the analog signal photoelectrically converted by the optical demodulator is detected. It is characterized by comprising a momentary interruption detection unit and a control unit that controls the signal selection unit based on the momentary interruption information of the analog signal detected by the momentary interruption detection unit.

In order to solve the above-mentioned problems, the invention according to claim 2 is characterized in that, in the optical receiving device, a level detecting part for detecting a signal level of an analog signal converted by the optical demodulator, and the level detecting part. And a control unit that controls the signal selection unit based on the detected signal level of the analog signal. In order to solve the above-mentioned problems, the invention according to claim 3 converts the communication data into light having different wavelength characteristics and radiates it into space, and converts the received light having different wavelength characteristics into communication data. In the optical communication system including the optical receiving device for performing optical communication through space, the optical receiving device receives the light emitted from the transmitting device, and the optical receiving device receives the light. A plurality of optical demodulators for photoelectrically converting light having different wavelength characteristics into analog signals, a signal detector for detecting analog signals converted by the optical demodulators into digital signals, and a detector for detecting the analog signals A signal selecting section for selecting a digital signal, a level detecting section for detecting a signal level of each analog signal converted by the optical demodulator, and an analog detected by the level detecting section. Characterized by comprising a control unit for controlling the signal selection section based on the signal level of the item.

[0008]

According to the first aspect of the invention, in the optical transmitter, the optical modulator performs optical modulation based on the analog signal added with the communication data, and the optical fiber transmits the optically modulated light. The light emitting unit emits the light transmitted by the optical fiber into the space. In the optical receiver, the light receiving unit receives the emitted light,
The optical fiber transmits the received light. The optical demodulator photoelectrically converts the light transmitted through the optical fiber into an analog signal, and the signal detector detects the analog signal into a digital signal. The instantaneous interruption detection unit detects the instantaneous interruption of the analog signal photoelectrically converted by the optical demodulator, and the control unit controls the signal selection unit based on the instantaneous interruption information of the analog signal detected by the instantaneous interruption detection unit. The selection unit selects the digital signal detected by the detector.

Therefore, even if one transmission line is blocked by installing a plurality of receiving units and separating the transmission line into a plurality of transmission lines, information transmission can be continued by the remaining transmission lines. According to a second aspect of the present invention, in the optical receiving device according to the first aspect, the level detection section detects the signal level of the analog signal converted by the optical demodulator, and the control section detects the analog level detected by the level detection section. The signal having the highest signal level is selected based on the signal level of the signal, and the signal selection by the signal selection unit is controlled.

Therefore, the receiving side monitors the receiving states of the plurality of light receiving parts and automatically switches to the signal of the light receiving part having the best receiving state, so that the information transmission can be continued while maintaining the best receiving condition. You can According to the invention of claim 3, in the optical transmitter, the optical modulator optically modulates each of a plurality of different wavelengths based on the analog signal to which the communication data is added, and the optical fiber is optically modulated by the optical modulator to each of the plurality of wavelengths. Each modulated light is transmitted. Next, the light emitting unit emits the light transmitted by the optical fiber into the space.

In the light receiving device, the light receiving section receives the light emitted from the light emitting section and having different wavelength characteristics, and the optical fiber transmits the light received by the light receiving section. The optical demodulator photoelectrically converts the received lights having different wavelength characteristics into analog signals, and the signal detector detects the analog signals converted by the optical demodulator into digital signals. Next, the level detection unit detects the signal level of each analog signal converted by the optical demodulator, and the control unit controls the signal selection unit based on the signal level of the analog signal detected by the level detection unit. The selection unit selects the digital signal detected by the detector.

Therefore, in the light receiving section, the signal level of each wavelength is monitored separately, and the signal with the best reception state is selected and treated as a reception signal. Therefore, information transmission is performed while maintaining the reception state in the best state. Can continue.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. (Embodiment 1) First, a system configuration of an optical communication system will be described. FIG. 1 is a system configuration diagram of an optical communication system which is an embodiment of the present invention (claim 1).

In FIG. 1, the terminal 1 outputs internally processed data. The modem 2 modulates the data output from the terminal 1 and converts it into an analog signal. Amplifier 3
Amplifies the analog signal output from the modem 2 to a specified level. The optical modulator 4 adds a bias current to the analog signal amplified by the amplification unit 3 to a specified level to generate an applied current, and directly modulates the infrared light emitting element. An optical fiber is connected to the infrared light emitting element directly modulated by the optical modulator 4, and the other end of the optical fiber is connected to the light emitting section 5. The light emitting unit 5 is connected to the optical fiber connected to the optical modulator 4 and directly radiates the modulated infrared light into the space. Optical transmitter 10
Reference numeral 1 is a device on the light emitting side that converts communication data into light and radiates it into space.

The light receiving sections 6 to 8 receive the infrared rays output from the light emitting section 5 and connect them to the optical fiber. Optical demodulator 9
Is a light receiving element corresponding to each of the light receiving units 6 to 8 for converting the infrared light sent via the optical fiber into an analog signal. The amplification unit 10 amplifies the analog signal output from the optical demodulator 9, respectively. The detector 11 detects a momentary interruption of each analog signal amplified by the amplification unit 10 and also detects the level of each analog signal. Then, after adding a limiter to the analog signal, each analog signal is detected and converted into a digital signal, and the digital signal is selectively output by a selector existing inside. The control unit 12 switches the selector existing inside the detector 11 based on the instantaneous interruption information of each analog signal detected by the detector 11 and the level information of each analog signal, and sends the digital signal to the modem 13. Output. The modem 13 demodulates the digital signal output from the wave detector 11, and also performs signal format conversion according to the access control system of the connected LAN. The optical receiving device 102 converts the received light into communication data and converts it into a LAN.
It is a device on the light receiving side for outputting to.

FIG. 2 is a layout diagram in which the light emitting portions or the light receiving portions of the optical communication system according to an embodiment of the present invention (claim 1) are installed in a matrix on the ceiling. As shown in Figure 1,
The light emitting unit 5 is arranged near the terminal, and the plurality of light receiving units 6 to 7 are arranged on the ceiling. The optical signal guided to the light emitting section 5 by the optical fiber is emitted by the spectroscope while changing its direction.

On the light receiving side, the transmission line having the highest reception level among the plurality of light receiving units 6 to 7 is treated as communication information. Optical communication is performed between terminals, but the light receiving parts are arranged in a square matrix on the ceiling side, and which light receiving part corresponds to the light emitting part depends on the network installed on the ceiling side in advance. Register and control.

FIG. 3 is a block diagram showing the relationship between the detector and the control unit of the optical communication system according to the embodiment (Claim 1) of the present invention. In FIG. 3, the inside of the amplification unit 10 is composed of amplifiers 10-1 to 10-3, and amplifies the analog signals output from the optical demodulator 9, respectively. In the inside of the detector 11, the instantaneous interruption detection units 11-1 to 11-3.
Detects instantaneous interruption of each analog signal amplified by the amplifier 10. The level detectors 11-4 to 11-6 are
The level of each analog signal is detected. The signal detection units 11-7 to 11-9 detect the respective analog signals and convert them into digital signals after adding a limiter to the analog signals. The selector 11-10 includes the signal detector 1
The digital signal output from 1-7 to 11-9 is selected. The control unit 12 detects the instantaneous interruption information of each analog signal detected by the instantaneous interruption detection units 11-1 to 11-3 and the level information of each analog signal.
The selector 11-10 existing inside is switched to output a digital signal to the modem 13.

Next, the function and effect will be described. In the optical transmitter, the optical modulator performs optical modulation based on the analog signal to which communication data is added, and the optical fiber transmits the optically modulated light. The light emitting unit emits the light transmitted by the optical fiber to the space. In the optical receiver, the light receiving unit receives the emitted light and the optical fiber transmits the received light. The optical demodulator photoelectrically converts the light transmitted through the optical fiber into an analog signal, and the signal detector detects the analog signal into a digital signal. The instantaneous interruption detection unit detects the instantaneous interruption of the analog signal photoelectrically converted by the optical demodulator, and the control unit controls the signal selection unit based on the instantaneous interruption information of the analog signal detected by the instantaneous interruption detection unit. The selection unit selects the digital signal detected by the detector.

Therefore, even if one transmission line is blocked by installing a plurality of receiving units and dividing the transmission line into a plurality of transmission lines, information transmission can be continued by the remaining transmission lines. (Embodiment 2) This embodiment (claim 2) can also be applied to the optical communication system described in FIG.
In this embodiment, a characteristic part of the present invention (claim 2) will be specifically described. FIG. 3 is a block diagram showing the relationship between the detector and the control unit of the optical communication system which is an embodiment of the present invention (claim 2).

In the optical receiver, when the level detector detects the signal level of the analog signal converted by the optical demodulator, the controller detects the highest level among the analog signal levels detected by the level detector. Signal is selected and the signal selector is switched and controlled. The effects of the present invention will be described below.

In the optical transmitter, the optical modulator performs optical modulation based on the analog signal added with the communication data, and the optical fiber transmits the optically modulated light. The light emitting unit emits the light transmitted by the optical fiber to the space. In the optical receiver, the light receiving unit receives the emitted light and the optical fiber transmits the received light. The optical demodulator photoelectrically converts the light transmitted through the optical fiber into an analog signal, and the signal detector detects the analog signal into a digital signal. The level detector detects the level of the analog signal photoelectrically converted by the optical demodulator, the controller controls the signal selector based on the level information of the analog signal detected by the level detector, and the signal selector detects the signal. Select the digital signal detected by the detector.

Therefore, the receiving side monitors the receiving states of the plurality of light receiving units and automatically switches to the signal of the light receiving unit having the best receiving state, so that the information transmission can be continued while maintaining the best receiving state. You can (Embodiment 3) First, the system configuration of the optical communication system will be described.

FIG. 4 is a system configuration diagram of an optical communication system which is an embodiment of the present invention (claim 3). In FIG. 4, the modem 31 modulates communication data and converts it into an analog signal. The amplifier 32 amplifies the analog signal output from the modem 31 to a specified level. Light modulator 33
Applies a bias current to the analog signal amplified by the amplifier 32 to a specified level to generate an applied current, and directly modulates the light emitting elements having different wavelengths. The respective optical fibers are connected to the light emitting elements having different wavelengths which are directly modulated by the optical modulator 33, and the other ends of the optical fibers are connected to the light emitting portions 34 to 36, respectively. The light emitting units 34 to 36 are connected to the respective optical fibers connected to the optical modulator 33, and radiate the directly modulated light to the transmission path. The optical transmission device 103 is a device on the light emitting side that converts communication data into light and emits the light to space.

The light receiving portions 37 to 39 receive the light output from the light emitting portions 34 to 36 and connect them to the optical fibers.
The optical demodulator 40 is a light-receiving element corresponding to each of the light-receiving units 37 to 39 that converts the light transmitted via the optical fiber into an analog signal. The amplification unit 41 includes the optical demodulator 40.
Each of the analog signals output from is amplified. The detector 42 detects the instantaneous interruption of each analog signal amplified by the amplifier 41, and also detects the level of each analog signal. Then, after adding a limiter to the analog signal, each analog signal is detected and converted into a digital signal, and the digital signal is selectively output by a selector existing inside. The control unit 43 switches the selector existing inside the detector 42 based on the instantaneous interruption information of each analog signal detected by the detector 42 and the level information of each analog signal, and sends the digital signal to the modem 44. Output. The modem 44 demodulates the digital signal output from the wave detector 42 and outputs communication data to the connected terminal. The light receiving device 104 is a light receiving device that converts received light into communication data and outputs the communication data to a terminal.

FIG. 2 is a layout diagram in which the light emitting portions or the light receiving portions of the optical communication system according to an embodiment of the present invention (claim 1) are installed in a matrix on the ceiling. As shown in FIG.
The light emitting units 34 to 36 are arranged on the ceiling, and the plurality of light receiving units 37 to
39 is arranged near the terminal. The optical signals guided by the optical fibers to the light emitting units 34 to 36 are emitted while changing their directions toward the respective light receiving units.

On the light receiving side, the transmission line having the highest reception level among the plurality of light receiving units 34 to 36 is treated as communication information. Optical communication is performed between terminals, but the light receiving parts are arranged in a square matrix on the ceiling side, and which light receiving part corresponds to the light emitting part depends on the network installed on the ceiling side in advance. Register and control.

FIG. 3 is a block diagram showing the relationship between the detector and the control unit of the optical communication system according to the embodiment (Claim 1) of the present invention. In FIG. 5, the inside of the amplification unit 41 is composed of amplifiers 41-1 to 41-3, and the optical demodulator 40
Each of the analog signals output from is amplified. Inside the wave detector 42, the instantaneous interruption detection units 42-1 to 42-
3 detects a momentary interruption of each analog signal amplified by the amplifier 41. Level detectors 42-4 to 42-6
Detects the level of each analog signal. The signal detectors 42-7 to 42-9 add limiters to the analog signals, and then detect the respective analog signals and convert them into digital signals. The selector 42-10 selects the digital signal output from the signal detection units 42-7 to 42-9. The control unit 43 controls the instantaneous interruption detection units 42-1 to 42-.
The selector 42-10 existing inside the detector 42 is switched based on the instantaneous interruption information of each analog signal detected in 3 and the level information of each analog signal,
The digital signal is output to the modem 44. Next, the modem 4
The communication data is output to the terminal connected to No. 4.

Next, the function and effect will be described. In the optical transmitter, an optical modulator optically modulates each of a plurality of different wavelengths based on an analog signal to which communication data is added, and an optical fiber transmits each light optically modulated to a plurality of wavelengths by the optical modulator. . Next, the light emitting unit emits the light transmitted by the optical fiber into the space.

In the optical receiver, the light receiving section receives the light emitted from the light emitting section, and the optical fiber transmits the light received by the light receiving section. The optical demodulator photoelectrically converts the light transmitted through the optical fiber into an analog signal, and the signal detector detects the analog signal converted by the optical demodulator into a digital signal. Next, the level detection unit detects the signal level of each analog signal converted by the optical demodulator, and the control unit controls the signal selection unit based on the signal level of the analog signal detected by the level detection unit. The selection unit selects the digital signal detected by the detector.

Therefore, by separately monitoring the signal levels of the respective wavelengths in the light receiving section, the signal with the best reception state is selected and treated as a reception signal, so that information transmission is performed while maintaining the reception state in the best state. Can continue.

[0032]

According to the present invention, by using a plurality of light emitting units or light receiving units, it is possible to reduce the communication interruption due to the interruption of the transmission path and select the signal with the best reception state. It is possible to perform high-speed, large-volume data communication by optical data communication.

[Brief description of drawings]

FIG. 1 is a diagram showing a system configuration of an optical communication system according to the present invention.

FIG. 2 is a layout view in which light emitting units or light receiving units of an optical communication system according to an embodiment of the present invention are installed in a matrix on a ceiling.

FIG. 3 is a block diagram showing the relationship between the detector and the control unit of the optical communication system which is an embodiment of the present invention.

FIG. 4 is a diagram showing a system configuration of an optical communication system according to the present invention.

FIG. 5 is a block diagram showing the relationship between the wave detector and the control unit of the optical communication system according to the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Terminal 2 Modem 3 Amplifying section 4 Optical modulator 5 Light emitting section 6 Light receiving section 7 Light receiving section 8 Light receiving section 9 Optical demodulator 10 Amplifying section 10-1 Amplifier 10-2 Amplifier 10-3 Amplifier 11 Detector 11-1 Instantaneous interruption Detecting section 11-2 Instantaneous interruption detecting section 11-3 Instantaneous interruption detecting section 11-4 Level detecting section 11-5 Level detecting section 11-6 Level detecting section 11-7 Signal detecting section 11-8 Signal detecting section 11-9 Signal Detection unit 11-10 Selector 12 Control unit 13 Modem 31 Modem 32 Amplifying unit 33 Optical modulator 34 Light emitting unit 35 Light emitting unit 36 Light emitting unit 37 Light receiving unit 38 Light receiving unit 39 Light receiving unit 40 Optical demodulator 41 Amplifying unit 41-1 Amplifier 41 -2 amplifier 41-3 amplifier 42 wave detector 42-1 instantaneous interruption detection section 42-2 instantaneous interruption detection section 42-3 instantaneous interruption detection section 42-4 level detection section 42-5 level detection section 42 -6 Level Detection Section 42-7 Signal Detection Section 42-8 Signal Detection Section 42-9 Signal Detection Section 42-10 Selector 43 Control Section 44 Modem 45 Terminal 101 Optical Receiver 102 Optical Transmitter 103 Optical Transmitter 104 Optical Receiver

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical indication H04B 10/22

Claims (3)

[Claims] 1. An optical communication system comprising an optical transmitter for converting communication data into light and radiating the light into space, and an optical receiver for converting the received light into communication data, and performing optical communication through the space. In the optical receiving device, the light receiving device receives a light emitted from the transmitting device, an optical demodulator photoelectrically converts the light received by the light receiving device into an analog signal, and the optical demodulator converts the light. A signal detector that detects an analog signal into a digital signal, a signal selection unit that selects the digital signal detected by the detector, and a momentary interruption that detects a momentary interruption of the analog signal photoelectrically converted by the optical demodulator. An optical communication system comprising: a detection unit; and a control unit that controls a signal selection unit based on instantaneous interruption information of an analog signal detected by the interruption detection unit. 2. In the optical receiving device, a level detecting section for detecting a signal level of an analog signal converted by the optical demodulator, and the signal based on the signal level of the analog signal detected by the level detecting section. The optical communication system according to claim 1, further comprising a control unit that controls the selection unit. 3. An optical transmitter, which converts communication data into light having different wavelength characteristics and emits the light to space, and an optical receiver which converts received light having different wavelength characteristics into communication data. In an optical communication system for performing optical communication via a light receiving device, the light receiving device receives a light emitted from the transmitting device and a light having different wavelength characteristics received by the light receiving device into an analog signal. A plurality of optical demodulators that each perform photoelectric conversion, a signal detector that detects each analog signal converted by the optical demodulator into a digital signal, and a signal selection unit that selects the digital signal detected by the detector,
A level detector that detects the signal level of each analog signal converted by the optical demodulator; and a controller that controls the signal selector based on the signal level of the analog signal detected by the level detector. An optical communication system characterized by being provided.