JP5548888B2 - Laser communication machine - Google Patents

Description

  The present invention relates to a laser communication device, and more particularly to a laser communication device suitable for laser communication between a laser communication device installed on the ground and a laser communication device mounted on a moving vehicle or the like.

  FIG. 5 is a diagram showing a configuration of a conventional laser communication device. FIG. 5A is a front view and FIG. 5B is a side view. FIG. 6 is a diagram showing how the conventional laser communication device is used. The conventional laser communicator includes a laser communicator 10 having a beacon detection quadrant sensor 11 and a laser transmitter / receiver 12, a laser beam controller 20, a mirror actuator 31, a movable mirror 32, and a beacon transmitter 40. The laser communication device of this configuration is used as the laser communication device 211 installed on the ground and the laser communication device 212 mounted on the moving body 61 traveling on the road 60, and laser communication is performed between these laser communication devices. To do. The beacon transmitter 40 transmits light at a wide angle of 20 to 30 degrees in order to inform the partner laser communicator of the position where the laser communicator exists. The beacon detection quadrant sensor 11 detects the beacon light from the partner beacon transmitter 40 and detects whether or not its movable mirror 32 is directed in a desired direction. That is, it is detected by the movable mirror 32 whether the laser beam transmitted for communication is directed in the arrival direction of the partner beacon light. Based on this detection signal, the laser beam controller 20 sends a drive signal to the mirror actuator 31 so as to cancel the direction of the laser beam if it is shifted up, down, left or right with respect to the arrival direction of the partner beacon light. Then, the movable mirror 32 is driven, and the laser beam is directed to the arrival direction of the partner beacon light, and laser communication with the partner laser communication device is performed by the laser transmitter / receiver 12 (see, for example, Patent Document 1).

  This conventional technique can be used when there is little physical vibration or the like, or when the moving speed is slow.

  However, this conventional laser beam control only controls the transmission direction of its own communication laser beam in the direction in which the partner beacon light comes, and the laser beam is correctly transmitted by the partner laser receiver. There is a problem that it is not confirmed that it is received. This method is called open loop control here. Moving bodies that move at high speeds are subject to intense vibrations. With this open loop control, if the light receiving range of the laser beam is narrowed, the laser spot will not stably strike the receiver on the other side, and as a result, the transmitted data can be received correctly. There is a problem of disappearing.

  The communication distance of laser light has a large relationship with the radiation angle. As long as the same laser device is used, the communication distance is short when the radiation angle is widened, and the communication distance is long when the radiation angle is narrow. Considering the application of laser communication to railway environments, it is necessary to secure a sufficient communication distance, so the light receiving range of laser light should be as narrow as possible.

  FIG. 12 is a diagram showing a usage mode of another conventional laser communication device. When the mobile body 61 traveling on the rail 60 and the base stations 71 to 74 perform laser communication, when the mobile body 61 moves during communication with the # 1 base station 71, the communication is switched to communication with the # 2 base station 72. It is necessary to switch communication one after another. For this reason, conventionally, it is known that light is transmitted from a fixed base station to a wide range (or received from a wide range) so that the communication area is not interrupted on the rail 60 (for example, Patent Documents). 2). However, in this case, since the light beam is expanded, long-distance communication cannot be performed, and so many base stations must be used. For this reason, it is not possible to take advantage of the characteristics of laser communication that enables long-distance communication.

  FIG. 13 is a diagram showing the configuration of still another conventional laser communication device. This conventional laser communicator enables communication over a long distance, and the # 1 laser communicator 241 and the # 2 laser communicator 242 have the same configuration. The laser communication devices 241 and 242 include a beacon transmitter 101, a movable mirror 102, a mirror actuator 103, a telephoto lens 104, a telephoto sensor 105, a laser beam controller 108, and a laser transceiver 109. First, beacon light from the beacon transmitter 101 of the # 2 laser communication device 242 is received by the telephoto sensor 105 via the movable mirror 102 and the lens 104. As the telephoto sensor 105, the quadrant sensor 11 shown in FIG. 2 is generally used. If the image of the beacon light is projected by the lens 104 at the center of the quadrant sensor 11, the device is directed in a desired direction. If the image is projected at a position other than the center of the quadrant sensor 11, the spot is Depending on which of the four light receiving sections 11a, 11b, 11c, and 11d is applied, it is possible to detect whether the apparatus is shifted from the desired direction, up and down, or left and right. Based on this deviation in direction, the laser beam controller 108 can correct the direction of laser beam transmission / reception by driving the movable mirror 102 by the mirror actuator 103, and can correctly direct it in the desired direction. As a result, both laser transceivers 109 can perform laser communication. As a typical apparatus for correcting the direction of laser beam transmission / reception, a system in which the entire laser communication device is mounted on a turntable called a gimbal, and one or two mirrors shown in FIG. There are two methods of controlling the direction of the beam by moving it. In the gimbal method, communication is established by mechanically directing the entire laser device in a desired direction, and in the mirror method, communication is established by correcting the direction of the mirror. However, with the above two systems, it is impossible to perform handover between terrestrial base stations while the mobile body moves at high speed. First, since the gimbal method rotates the entire device, it is difficult to increase the operating speed, and the direction of the mobile laser communicator can be quickly changed from one base station to the next. Is physically impossible. In addition, in the method of controlling the beam direction by mechanically moving one or two mirrors, it is possible to move the mirror quickly, but as long as a telephoto sensor is used for beacon detection, the current link is used. There is only a function of tracking the direction of a base station, and the function of detecting the next base station and directing the beam in that direction cannot be realized.

JP 07-264135 A JP 2001-168803 A

  In view of the above-described problems, the present invention provides a laser communication device that allows a remote receiver having a narrow light receiving range to receive a laser beam reliably when a thin laser beam is transmitted in the arrival direction of the counterpart beacon light. The purpose is to provide.

The laser communication device of the present invention is a light reception position detector for detecting a two-dimensional reception position of laser light from the partner laser communication device, and for notifying the partner laser communication device of the presence position of the laser communication device. A beacon transmitter that modulates and transmits a beacon light according to information about the reception position, and a laser transceiver that performs laser communication with the counterpart laser communication device using a laser beam different from the beacon light. .

  Further, the beacon transmitter can control the transmission direction of the laser light more accurately by modulating and transmitting the beacon light according to the information on the laser reception status in the laser transceiver.

In addition, the laser communication device of the present invention receives beacon light for informing the location of the partner laser communication device, detects the presence direction of the partner laser communication device, and detects the laser communication in the partner laser communication device. A beacon receiver that demodulates information relating to a two-dimensional reception position of laser light from a laser, a laser transceiver that performs laser communication with the counterpart laser communication device using the laser light, and the direction and demodulation of the counterpart laser communication device And a transmission light direction controller for controlling the transmission direction of the laser light based on the received reception position information.

  The beacon receiver also demodulates information on the laser reception status in the partner laser communication device, and the transmission light direction controller controls the transmission direction of the laser light based on the demodulated laser reception status information. The transmission direction of the laser beam can be controlled more accurately.

  ADVANTAGE OF THE INVENTION According to this invention, even if it narrows the light-receiving range of a laser beam, the laser communication apparatus which a laser spot stably hits the other party receiver can be provided.

It is a figure which shows the structure of the laser communication apparatus by Example 1. FIG. It is a figure which shows the specific structure of a 4-part dividing sensor. It is a figure which shows the usage condition of the laser communication apparatus of Example 1. FIG. FIG. 6 is a diagram for explaining the operation of the first embodiment. It is a figure which shows the structure of the conventional laser communication apparatus. It is a figure which shows the usage condition of the conventional laser communication apparatus. It is a figure which shows the usage condition of the laser communication apparatus by Example 2. FIG. FIG. 10 is a diagram for explaining the operation of the second embodiment. It is a figure which shows the structure of the laser communication apparatus by Example 2. FIG. It is a figure which shows the structure of the laser communication apparatus by Example 3. FIG. It is a figure which shows the structure of PSD. It is a figure which shows the usage condition of another conventional laser communication apparatus. It is a figure which shows the structure of another conventional laser communication apparatus.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a diagram illustrating a configuration of a laser communication device according to the first embodiment. FIG. 1A is a front view, and FIG. 1B is a side view. FIG. 2 is a diagram showing a specific structure of the quadrant sensor. FIG. 3 is a diagram illustrating a usage mode of the laser communication device according to the first embodiment. The laser communicator of the present embodiment includes a laser communicator 10 having a quadrant sensor 11 for beacon detection and a laser transmitter / receiver 12, a laser beam controller 20, a mirror actuator 31, a movable mirror 32, a beacon transmitter 40, and a laser spot. It consists of light intensity sensors 50a, 50b, 50c, 50d. As shown in FIG. 2, the beacon detection quadrant sensor 11 includes light receiving portions 11 a, 11 b, 11 c, and 11 d that are divided into four by a ten-character split line. The arrival direction of the beacon light can be detected by comparing the intensity of the output signal corresponding to the light reception intensity in the light receiving units 11a, 11b, 11c, and 11d. The laser communication device having this configuration is used as the laser communication device 201 installed on the ground and the laser communication device 202 mounted on the moving body 61 traveling on the rail 60, and laser communication is performed between these laser communication devices. I do. Compared with the prior art described in FIGS. 5 and 6, the configuration of this embodiment is provided with laser spot light intensity sensors 50 a, 50 b, 50 c, and 50 d, and a status signal from the laser transceiver 12 (for example, The difference is that the laser beam reception intensity and PLL (phase-locked loop) lock state, etc.) are sent to the laser beam controller 20.

  Regarding the laser beam direction control, first, as in the conventional method, the beacon detection quadrant sensor 11 detects the beacon light from the partner beacon transmitter 40 and its own movable mirror 32 faces in a desired direction. Detect whether or not. That is, it is detected by the movable mirror 32 whether the laser beam transmitted for communication is directed in the arrival direction of the partner beacon light. Based on this detection signal, the laser beam controller 20 sends a drive signal to the mirror actuator 31 so as to cancel the direction of the laser beam if it is shifted up, down, left or right with respect to the arrival direction of the partner beacon light. Then, the movable mirror 32 is driven, the direction of the laser beam is directed to the arrival direction of the partner beacon light, and laser communication is performed with the partner laser communicator by the laser transmitter / receiver 12. Up to this point, the process is the same as in the conventional method, but the present embodiment also performs the following processing. The laser spot light intensity sensors 50a, 50b on the other side indicate whether the laser spot is correctly hit on the other side when the laser beam is directed toward the other side in the direction of the mirror actuator 31 controlled by the above method. Detection is performed by status signals (for example, laser beam reception intensity, PLL lock state, etc.) from 50c and 50d and the laser transceiver 12, and the detected data is sent back by modulating the beacon light. This information is demodulated by its own beacon detection quadrant sensor 11 to grasp the reception status of the other party. By comparing the laser spot light intensities detected by the laser spot light intensity sensors 50a, 50b, 50c, and 50d (four in the example of FIG. 1) among the information coming from the other party, the laser of the other party It can be seen whether it is hitting a desired spot of the receiver on the side or whether it is slightly shifted up and down and left and right. For example, when the laser spot light intensity sensor 50a installed on the upper side of the four laser spot light intensity sensors detects a laser spot light stronger than the other three laser spot light intensity sensors 50b, 50c, 50d. It can be seen that the desired spot on the other side is shifted to the upper side. In addition, by detecting a status signal (for example, laser beam reception intensity, PLL lock status, etc.) from the laser transmitting / receiving apparatus, which is another information, it can be determined whether or not the other party is surely receiving. That is, the information can be received if the laser beam reception intensity on the other side is higher than a certain level, and further, if the PLL of the reception circuit on the other side is locked, this is information indicating that reception is possible.

  As a method for modulating the beacon light, any modulation can be used. For example, a sine wave or a rectangular wave having a specific frequency of the beacon light is generated and the frequency is modulated (frequency shift keying (FSK)). Alternatively, data can be transmitted by modulating the phase (phase shift keying (PSK)).

  FIG. 4 is a diagram for explaining the operation of the first embodiment. 4A is a flowchart for its own mirror control, and FIG. 4B is a flowchart for transmitting information for mirror control of the partner side. First, in order to control its own mirror, a signal from the quadrant sensor 11 is input (step S1), and a laser beam is transmitted from the laser transmitter / receiver 12 in the direction of arrival of the beacon light based on the signal from the quadrant sensor 11. , The output to the mirror actuator 31 is calculated to control the mirror actuator 31 (this is the primary control) (step S2). Next, beacon light is received by the four-divided sensor 11 (step S3), and it is determined whether or not a sufficient amount of beacon light is received for demodulation (step S4). If the beacon light cannot be received, the process returns to step S1. If yes, it is possible to receive the beacon light enough to be demodulated, the process proceeds to step S5, where the received light signal is demodulated, the signals from the counterpart laser spot light intensity sensors 50a, 50b, 50c, 50d and the laser transceiver The state signal from 12 is acquired (step S5). Based on these signals, the direction of the movable mirror 32 is calculated and the mirror actuator 31 is controlled so that its own laser spot is at a desired position on the other side or the state of the laser transmitter / receiver 12 is the best ( This is a secondary control performed following the primary control) (step S6). On the other hand, for the mirror control on the other side, signals from the laser spot light intensity sensors 50a, 50b, 50c, 50d are input (step S11), and further, a status signal is input from the laser transceiver 12 (step S11). S12), the signals from these laser spot light intensity sensors 50a, 50b, 50c, 50d and the status signal from the laser transmitter / receiver 12 are transmitted to the other party by modulating the beacon light (step S13). As a result, information on the laser beam reception status is transmitted to the other party before normal laser communication is started, so that the side receiving it transmits the laser beam to an appropriate position using the information. can do.

  FIG. 7 is a diagram illustrating how the laser communication device according to the second embodiment is used. Both the wide-angle sensor and the telephoto sensor are used for the moving body 61 such as a vehicle traveling on the rail 60 and the laser communication devices of all the base stations 71 to 74 connected to the optical fiber network (FIG. 9). The telephoto sensor of the mobile unit 61 is used to track the communication partner on the base stations 71 to 74, and the telephoto sensor on the base station 71 to 74 side similarly tracks the communication partner of the mobile unit 61. Used to do. On the other hand, the wide-angle sensor of the mobile body 61 is used to find and capture the base stations 71 to 74 that perform handover, and the wide-angle sensor on the base station 71 to 74 side is also used to find the communication partner of the mobile body 61. It is done. First, in the state shown in FIG. 7A, the moving body 61 communicates with the # 1 base station 71 and tracks the laser beam using a telephoto sensor. Next, when the moving body 61 gradually moves to the left and enters the state shown in FIG. 7B, the wide-angle sensor detects the beacon light of the next base station (# 2 base station 72). The laser communication device of the moving body 61 changes the direction of the laser beam to the direction of the # 2 base station 72. Similarly, the laser communication device of the # 2 base station 72 changes the direction of the laser beam to the direction of the moving body 61. On the other hand, a laser communication link is established between the mobile unit 61 and the # 2 base station 72, and the state shown in FIG. As long as the mobile 61 is in the range of the # 2 base station 72, this communication link is continued by tracking the laser beam using the telephoto sensor. When the wide-angle sensor of the moving body 61 detects the beacon light of the next base station (# 3 base station 73), the handover is performed from the # 2 base station 72 to the # 3 base station 73 as described above.

  FIG. 8 is a diagram for explaining the operation of the second embodiment. First, initial capture is performed by controlling the mirror actuator based on a signal from a wide-angle sensor for detecting a beacon so that the movable mirror is directed in a general direction (step S21). Next, tracking is started by controlling the mirror actuator based on the signal from the telephoto sensor for detecting the beacon so that the movable mirror is directed in the correct direction (step S22). While continuing tracking, a signal from a wide-angle sensor for detecting a beacon is input (step S23), and it is determined whether or not a strong beacon signal is detected (step S24). If no and a strong beacon signal is not detected, the process returns to step S22 to continue tracking. If it is yes and a strong beacon signal is detected, it means that the next base station has been detected. Therefore, the laser beam is directed in that direction to perform capture (step S25), and the base station returns to step S22. Start tracking against. By repeating this, the mobile side communicates while handing over with the base stations that pass one after another. In addition, it is possible to capture and track a moving object passing by the same algorithm on the base station side.

  FIG. 9 is a diagram illustrating a configuration of a laser communication device according to the second embodiment. The in-vehicle # 1 laser communicator 221, the # 2 laser communicator 222 installed on the ground, and the # 3 laser communicator 223 all have the same configuration, and include a beacon transmitter 81, a movable mirror 82, a mirror actuator 83, and a wide angle. It comprises a lens 84, a wide angle sensor 85, a telephoto lens 86, a telephoto sensor 87, a laser beam controller 88, and a laser transceiver 89. The wide angle sensor 85 and the telephoto sensor 87 are constituted by four divided sensors. The # 1 laser communicator 221 is installed so as to communicate toward the rear of the moving body, and receives strong beacon light from a new laser communicator as it moves. The beacon light from the beacon transmitter 81 of the # 2 laser communicator 222 and the laser light from the laser transmitter / receiver 89 are reflected by the movable mirror 82 driven by the mirror actuator 83 of the # 1 laser communicator 221, and the wide angle sensor 85 is reflected. Enter the telephoto sensor 87 and the laser transceiver 89. When # 1 laser communicator 221 is communicating with # 2 laser communicator 222, beacon light is tracked by telephoto sensor 87 and laser communication is performed. When # 1 laser communicator 221 moves to the left and passes near # 3 laser communicator 223, wide angle sensor 85 of # 1 laser communicator 221 detects strong beacon light from # 3 laser communicator 223. To do. By detecting the strong beacon light of # 3 laser communicator 223, laser beam controller 88 of # 1 laser communicator 221 changes the direction of the mirror so that the laser beam is directed toward # 3 laser communicator 223. First, the wide angle sensor 85 is used to direct the # 3 laser communication device 223 in the approximate direction. After heading in the approximate direction, tracking is started using the telephoto sensor 87 so that the # 3 laser communicator 223 is directed in the correct direction, and communication between the # 1 laser communicator 221 and the # 3 laser communicator 223 is started. Is done.

  FIG. 10 is a diagram illustrating the configuration of the laser communication device according to the third embodiment. The in-vehicle # 1 laser communication device 231, the # 2 laser communication device 232 installed on the ground, and the # 3 laser communication device 233 all have the same configuration, and include a beacon transmitter 91, a movable mirror 92, a mirror actuator 93, and a wide angle. The lens 94, PSD 95, telephoto lens 96, telephoto sensor 97, laser beam controller 98, and laser transceiver 99 are included. The telephoto sensor 97 is constituted by a four-divided sensor. The third embodiment differs from the second embodiment in that a wide-angle lens 94 directly receives beacon light without using the movable mirror 92 by using a PSD 95 instead of the wide-angle sensor 85.

  FIG. 11 is a diagram illustrating the structure of the PSD. When light hits an arbitrary position (x, y) on the light receiving surface 101, the current flowing through the electrodes X1, X2, Y1, and Y2 changes depending on the position, so the position of the hit light is detected based on the current value. can do. Thus, since the direction of the light source can be detected by using the PSD 95, it is not necessary to perform mirror control so that the beacon light comes directly in front of the PSD 95. Therefore, in FIG. 10, there is no movable mirror 92 in front of the PSD 95, and the direction is detected by directly receiving the beacon light. In this way, since it is not necessary to use the light reflected by the PSD 95 as the light that hits the PSD 95, the size of the movable mirror 92 can be reduced, and as a result, the movable mirror 92 can be moved at a higher speed. be able to. The operations other than the PSD 95 are the same as when the quadrant sensor is used as the wide-angle sensor 85 shown in FIG.

  In addition, this invention is not limited to the said Example.

10 Laser communicator 11 Quadrant sensor 12, 89, 99, 109 Laser transceiver 20, 88, 98, 108 Laser beam controller 31, 83, 93, 103 Mirror actuator 32, 82, 92, 102 Movable mirror 40, 81 91, 101 Beacon transmitter 50 Laser spot light intensity sensor 60 Rail 61 Moving body 71-74 Base station 84, 94 Wide angle lens 85 Wide angle sensor 86, 96, 104 Telephoto lens 87, 97, 105 Telephoto sensor 95 PSD
101 Light-receiving surface 201, 202, 211, 212, 221-223, 231-233, 241, 242 Laser communication machine

Claims (4)

An optical reception position detector for detecting a two-dimensional reception position of the laser beam from the counterpart laser communication device;
A beacon transmitter that modulates and transmits a beacon light for notifying the partner laser communication device of the presence position of the laser communication device according to information on the reception position ;
A laser communication device comprising: a laser transmitter / receiver that performs laser communication with the counterpart laser communication device using a laser beam different from the beacon light.   2. The laser communication device according to claim 1, wherein the beacon transmitter modulates and transmits the beacon light according to information on a laser reception state in the laser transmitter / receiver. Receiving a beacon light for notifying the position of the partner laser communication device, detecting the direction of the partner laser communication device, and two-dimensionally the laser light from the laser communication device in the partner laser communication device A beacon receiver that demodulates information about a reception position; a laser transceiver that performs laser communication with the counterpart laser communication device by the laser light;
A laser communication device, comprising: a transmission light direction controller that controls a transmission direction of the laser light based on an existence direction of the counterpart laser communication device and demodulated reception position information. The beacon receiver also demodulates information on the laser reception status in the partner laser communication device, and the transmission light direction controller controls the transmission direction of the laser light based on the demodulated laser reception status information. The laser communication device according to claim 3.

Images