JP2001339350A - Mobile free-space optical space communication unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a mobile free-space optical space communication unit that can surely acquire a signal. SOLUTION: An arithmetic processing unit 44 of a fixed station receives position information of a mobile station positioned by a GPS unit by using a receiver 45, calculates the direction of a transmission light L21 on the basis of information, and outputs a drive signal to a longitudinal direction drive section 46 and a lateral direction drive section 47 provided to a transmission/ reception optical system 35 so that the transmission/reception optical system in directed in the direction of the mobile station. When mobile station uses an angle detection element to detect the transmission light L21 emitted from the fixed station, the mobile station immediately enters a tracking operation, allows the longitudinal direction drive section 46 and the lateral direction drive section 47 to drive the optical transmission reception optical system 35 to direct a received light L22 emitted from the mobile station in a direction of the fixed station and the fixed station receives the light L22 to start mutual communication.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile optical space communication apparatus for communicating by propagating light in free space.

[0002]

2. Description of the Related Art FIG. 5 is an explanatory view of a conventional mobile optical space transmission apparatus. For example, signal beams L1 and L2 are transmitted between a mobile station 1 such as a vehicle and a fixed station 2 installed beside a road. Are superimposed to perform communication. The mobile station 1 and the fixed station 2 perform a capturing operation for starting communication when the mobile enters a communicable area;
A function of performing a tracking operation for maintaining communication after capturing is required. In order to realize this, for example, an optical space communication device as shown in FIG. 6 is required.

FIG. 6 shows a configuration diagram of the free-space optical transmission apparatus. A main signal containing information to be transmitted is input from an input terminal 11 to a transmission section of the free-space optical communication apparatus. Is amplified. A so-called pilot signal, which is an auxiliary signal for angle detection, is generated in the oscillator 13, and the main signal and the pilot signal are multiplexed by the multiplexer 14. The electric signal is converted into an optical signal in the light emitting element 16 composed of a diode or the like, and the transmission optical system 17 forms a transmission light L11 having an appropriate divergent angle, which is emitted toward the partner device.

On the other hand, a received light L12 from a partner device enters a receiving optical system 18 for a main signal and a receiving optical system 19 for a pilot signal, and comprises an APD (avalanche photodiode), a PIN photodiode, and the like. The light is focused on the main signal light receiving element 20 and the angle detecting element 21. The main signal received by the main signal light receiving element 20 is converted from an optical signal to an electric signal, and output from the output terminal 23 via the amplifier 22.

On the other hand, the angle detecting element 21 comprises a photodiode having a structure divided into four elements, for example, elements 21a to 21d as shown in FIG.
1. Elements 21a to 21 when light spot S is condensed on 1
By comparing the output of d, the incident angle of the reception light L12 from the partner device with respect to the transmission / reception optical system 15 can be detected.

The angle signal from the angle detecting element 21 is subjected to arithmetic processing in an arithmetic processing section 24, so that a light spot S is applied to the center of the angle detecting element 21 so that the angle difference between the reception light L12 and the transmission / reception optical system 15 becomes zero. And the arithmetic processing unit 2
4 drives the vertical drive unit 25 and the horizontal drive unit 26.
The transmission optical system 17 and the reception optical systems 18 and 19 are adjusted so that the angles of the optical axes coincide with each other. As a result, the transmission light L11 is also emitted in the direction of the partner device. In this manner, the tracking operation is performed between the mobile station 1 and the fixed station 2.

[0007]

However, in the above-mentioned conventional example, in order to perform communication by the tracking operation function, the light beams L1 and L2 in FIG. 5 must be captured before the communication. The range in which signals can be captured by each other is limited to the range where the own device is included in the range of the light beam from the partner device and the required signal strength is obtained. Increasing the divergence angle of the light beam increases the light irradiation range, but reduces the signal intensity, thereby narrowing the range of the communicable distance.

Normally, the equipment of the fixed station 2 in the initial state is installed on the road with the communication distance slightly downward, and the equipment of the mobile station 1 is fixed at the communication distance. It is installed with a slightly upward position corresponding to the height of the station 2. In such a state, when the vehicle that is the mobile station 1 approaches the fixed station 2 and enters the irradiation range of each other, the angle detecting element 21 captures the light beam of the partner device and the tracking operation function operates.

However, as described above, the captureable range is limited, and there are fluctuations such as vertical swing of the vehicle due to road surface conditions, vertical tilt due to acceleration / deceleration, left / right tilt due to steering operation, etc. The vehicle may pass through the captureable range without being successfully captured. In this case, the automatic tracking function is not performed, and the communication cannot be performed at all. Thus, in the conventional device,
There is uncertainty in the initial signal acquisition to initiate communication.

An object of the present invention is to solve the above-mentioned problems,
It is an object of the present invention to provide a mobile optical space communication device capable of reliably capturing a signal.

[0011]

SUMMARY OF THE INVENTION A mobile optical space communication apparatus according to the present invention for achieving the above object communicates optically between a fixed station and a mobile station installed in a mobile body such as a vehicle. A mobile optical space communication device for performing, wherein the mobile station comprises:
Positioning means for receiving a radio wave from an artificial satellite to measure its own position, and means for wirelessly transmitting position information obtained by positioning by the positioning means to a fixed station, wherein the fixed station includes Means for wirelessly receiving position information from a station, means for determining whether or not the own station communicates with the mobile station based on the position information and own position of the mobile station, and obtaining an emission direction of a light beam. And driving means for directing the transmission light beam in the determined emission direction of the light beam.

A mobile optical free-space communication device according to the present invention is a mobile optical free-space communication device for performing optical wireless communication between a fixed station and a mobile station installed in a mobile body such as a vehicle. The mobile station has positioning means for receiving a radio wave from an artificial satellite to measure its own position, and means for wirelessly transmitting position information obtained by positioning by the positioning means to a control center, The fixed station wirelessly or wiredly receives from the control center the position information of the mobile station or the command information of the emission direction of the light beam, and the position information of the mobile station and the emission direction of the light beam from its own position. Arithmetic processing means for obtaining, and driving means for directing transmission light in the obtained emission direction of the light beam or driving for directing the transmission light in the emission direction based on command information on the emission direction of the light beam Having means And wherein the door.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail based on the illustrated embodiment. FIG. 1 shows a configuration diagram of an optical free space transmission apparatus on the fixed station side according to an embodiment of the present invention. The transmitting section is provided with an input terminal 31 for transmitting a main signal, and is connected to an amplifier 32. An oscillator 33 for generating a so-called pilot signal, which is an auxiliary signal for angle detection, is provided. The outputs of the amplifier 32 and the oscillator 33 are connected to a multiplexer 34. The output of the multiplexer 34 is connected to a light emitting element 36 such as a semiconductor laser or a light emitting diode provided in a transmission / reception optical system 35, and the light emitting element 3
The transmission optical system 37 is disposed in the traveling direction of the transmission optical system 6.

On the other hand, a receiving optical system 38 for the main signal and a receiving optical system 39 for the pilot signal are arranged in parallel in the incident direction of the light beam from the apparatus on the mobile station side. , A main signal light receiving element 40 including an APD, a PIN photodiode, and the like, and an angle detecting element 41 are disposed. The output of the main signal light receiving element 40 is connected to an output terminal 43 via an amplifier 42, and the output of the angle detecting element 41 is connected to an arithmetic processing unit 44.

The arithmetic processing unit 44 is connected to a radio wave receiving device 45 for receiving position information from a mobile station. Also,
The output of the arithmetic processing unit 44 is connected to a vertical driving unit 46 and a horizontal driving unit 47 provided in the transmission / reception optical system 35.

FIG. 2 is a schematic diagram of a mobile station. The mobile station 51 has a space optical communication device 52 having the same configuration as that shown in FIG. A so-called GPS device 53 for measuring the distance, longitude and altitude, and a radio wave transmitting device 54 for transmitting information obtained by the GPS device 53 are provided.

Normally, the GPS device 53 performs positioning based on the arrival time difference of radio waves from four artificial satellites. However, by acquiring correction data using radio waves from a reference station installed on the ground, positioning can be performed with an accuracy of about several meters. It is possible. In Japan, the correction data of the reference station is inserted in the data transmission channel of FM radio broadcasting.

The position information of the own device obtained by the GPS device 53 is converted into a position signal of an appropriate format by the transmission device 54, and then transmitted to the optical space transmission device of the fixed station.

A main signal input from an input terminal 31 of the fixed station shown in FIG. 1 is amplified to an electric signal of an appropriate level by an amplifier 32, and is combined with a pilot signal generated by an oscillator 33 by a multiplexer 34. You. The electric signal synthesized in the multiplexer 34 is input to a light emitting element 36 provided in a transmission / reception optical system 35. The light emitting element 36 converts an electric signal into an optical signal, and transmits the transmission light L via a transmission optical system 37.
As 21, it is transmitted to the device of the mobile station 51.

The received light L22 received from the free-space optical communication device 52 of the mobile station 51 is converted into a main signal receiving optical system 38 and a pilot signal receiving optical system 39 arranged in parallel.
Incident on. The received light L22 that has entered the receiving optical system 38 enters the main signal light receiving element 40 and is converted from an optical signal into an electric signal. Further, the converted electric signal is amplified by an amplifier 42 to an electric signal of an appropriate level,
3 is output. On the other hand, the reception light L22 that has entered the reception optical system 39 enters the angle detection element 41, is converted from an optical signal into an electric signal, and the converted electric signal is processed by the arithmetic processing unit 44.
Is input to

The arithmetic processing unit 44 calculates the emission direction of the transmission light L 21 based on the position information of the mobile station 51 received by the reception unit 45, and performs reception and transmission so that the transmission / reception optical system 35 is directed to the mobile station 51. A drive signal is output to a vertical drive unit 46 and a horizontal drive unit 47 provided in the optical system 35.

When the mobile station 51 detects the transmitted light L21 emitted from the fixed station by the angle detecting element, it immediately starts a tracking operation, and vertically moves the received light L22 emitted from the mobile station 51 so as to be directed to the fixed station. The directional drive unit and the lateral drive unit are driven, and the fixed station also receives the signal and starts a tracking operation to start mutual communication. The transmission optical system 37 and the reception optical system 39 are adjusted so that the angles of the optical axes coincide with each other. As a result, the transmission light L21 is driven in the direction of the device of the mobile station 51. Thus, the tracking operation is performed between the mobile station 51 and the fixed station.

Until the fixed station captures the transmitted light emitted from the mobile station and enters the communication state, the fixed station is driven to continue in the direction of the mobile station regardless of the change in the distance to the mobile station. Therefore, there is no limitation that the mobile station must succeed in capturing while the mobile station is in the capturing range of the fixed station, and a more reliable capturing operation can be performed.

FIG. 3 is an explanatory diagram of the communication method. Fixed stations 61 arranged at a certain interval on the road are shown in FIG.
The position information of the mobile station 51 transmitted from the mobile station 51 is received by using the radio wave receiving device 45 as shown in FIG. The arithmetic processing unit 44 performs the following processing based on the received position information.

First, the position of the mobile station 51 and a plurality of fixed stations 6 known in advance by being written in a memory or the like are determined.
1, it is determined whether or not the fixed station 61 is most suitable for communicating with the mobile station 51 based on whether or not it is closest to communicating with the mobile station 51.

Next, when one of the fixed stations 61 determines that its own position performs communication, the position of the mobile station 51, its own position, and the initial emission direction of the transmission light L21 of its own device are determined. The emission direction of the transmission light L21 is calculated from the direction of the unit, which is also a known direction, for example, which is also written in the memory, and a drive signal is output to the driving units 46 and 47 of the optical system 35 to output the transmission light L21. The direction is directed to the direction in which the mobile station 51 is located.

If the spread diameter of the received light L22 from the fixed station 61 is set to be larger than the accuracy of the GPS device 53, the mobile station 51 can transmit the transmitted light L21 from one fixed station 61.
As soon as the optical signal is detected by the angle detecting element 41, the mobile station 51 starts a tracking operation, the transmission light from the mobile station 51 is directed to the fixed station 61, and the fixed station 61 also changes the light. In response to this, a tracking operation is started, and mutual communication is started.

As described above, until the mobile station 51 grasps the transmission light L21 from the fixed station 61 and starts the tracking operation, the transmission light L21 from the fixed station 61 changes according to the change in the position of the mobile station 51. Track 51. Therefore, there is no restriction that the mobile station 51 must succeed in capturing while the mobile station 51 is in the capturing range of the fixed station 61, and a more reliable capturing operation can be performed.

In the above example, each fixed station 61 directly receives the position information from the mobile station 61. However, as shown in FIG. 4, a control center that manages a plurality of fixed stations 71 and the mobile station 51 collectively. 72 may be provided.

The location information from the mobile station 51 is transmitted to the control center 7.
2, the control center 72 transmits information or command signals to each fixed station 71 by wireless or wired communication means. In the case of wireless communication, the receiving device 45 of the fixed station 71 has a function of receiving a radio signal from the control center 72. In the case of wired communication, the fixed station 71 uses a line terminal such as a modem instead of the receiving device 45. A device is provided.

The signal from the control center 72 may take the following forms. First, the location information of the mobile station 51 is transmitted from the control center 72 to the fixed station 71,
Receives the information, calculates the direction of the transmission light L21 by calculation in the same manner as in the previous example, and directs it in that direction.

The fixed center 71 to be contacted is determined from the position of the fixed station 71 previously stored in the control center 72 and the position of the received mobile station 51, and the transmission light L21 of the fixed station 71 is determined. The direction is calculated by calculation, and a command signal indicating the beam direction is sent to the fixed station 71. The fixed station 71 transmits a transmission light toward the mobile station 51 in the designated direction based on the signal.

[0033]

As described above, the mobile optical free-space communication apparatus according to the present invention is a mobile optical free-space communication apparatus between a fixed station and a mobile station such as a vehicle. And means for transmitting the position information obtained by the positioning to the fixed station directly or via the control center, and the fixed station side directs the emission direction of the transmission light beam to the mobile station based on the position information. In addition, a capturing operation for the mobile station and the fixed station to capture each other's signals and start communication can be easily and reliably performed.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a free-space optical communication device on a fixed station side.

FIG. 2 is a schematic diagram of a mobile station.

FIG. 3 is an explanatory diagram of a mobile space communication method.

FIG. 4 is an explanatory diagram of a mobile space communication method.

FIG. 5 is an explanatory diagram of a conventional mobile optical space communication device.

FIG. 6 is a configuration diagram of a conventional optical space communication device.

FIG. 7 is an explanatory diagram of an angle detection element.

[Explanation of symbols]

 Reference Signs List 31 input terminal 35 transmission / reception optical system 37 transmission optical system 38, 39 reception optical system 40 light receiving element 41 angle detector 43 output terminal 44 arithmetic processing unit 45 radio wave receiver 46 vertical driving unit 47 horizontal driving unit 51 mobile station 52 light Spatial communication device 53 GPS device 54 Radio wave transmission device 61, 71 Fixed station 72 Control center

Claims (2)

[Claims] 1. A mobile optical space communication device for performing optical wireless communication between a fixed station and a mobile station installed on a mobile object such as a vehicle, wherein the mobile station receives a radio wave from an artificial satellite. And a means for wirelessly transmitting position information obtained by positioning by the positioning means to a fixed station, wherein the fixed station wirelessly transmits position information from the mobile station. Means for determining whether or not the own station communicates with the mobile station based on the position information and the own position of the mobile station, an arithmetic processing means for determining the emission direction of the light beam, And a driving unit for directing the transmission light beam in the emission direction of the light beam. 2. A mobile optical space communication device for performing optical wireless communication between a fixed station and a mobile station installed in a mobile object such as a vehicle, wherein the mobile station transmits radio waves from an artificial satellite. Positioning means for receiving and positioning the own position, and means for wirelessly transmitting position information obtained by positioning by the positioning means to a control center, the fixed station is wireless or wired from the control center Means for receiving the position information of the mobile station or command information of the emission direction of the light beam, arithmetic processing means for determining the emission direction of the light beam from the position information and the own position of the mobile station, Moving body light having driving means for directing the transmission light in the emission direction of the light beam or driving means for directing the transmission light in the emission direction based on command information on the emission direction of the light beam; Spatial communication device.