JP2005295441A - Wireless along railway monitor system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wireless along railway monitor system capable of easily judging whether or not the distance between base stations can be extended. <P>SOLUTION: A camera 12 photographs the periphery of a along-railway line. A transmitting side radio base station 16 transmits a monitor image to a receiving side radio base station installed together with a monitor. The radio base station 16 comprises an attenuation section 46 between a radio section 42 and an antenna 48. A switching section 42 performs switching operation to attenuate a transmitted signal on the attenuation section 44 and sets an extension judging mode for judging whether or not the distance between the base stations can be extended. The amount of attenuation due to the attenuation section 46 is set in accordance with an extension width of the distance between candidate base stations. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a wireless railway monitoring system that monitors railways using a monitoring camera and a wireless device that are simply installed along a train.

  2. Description of the Related Art Conventionally, surveillance systems that send images from surveillance cameras by communication have been used in various fields (see Patent Document 1).

  In situations such as disaster sites along the track, it is necessary to build a temporary radio monitoring system. Moreover, the installation location is often an inconvenient location such as a mountainous area. In such a case, a simple wireless system is preferably used. In the simple radio system, the radio base stations on the transmission side and the reception side are small and are simply installed using a tripod or the like.

  Conventionally, simple wireless base stations are arranged as follows. First, the positions of the reception point and the transmission point are selected so that a line of sight from the reception point to the transmission point can be secured using a mirror, a laser, or the like. Next, the antenna is arranged so as to face the transmission point and the reception point. A fixed radio wave is transmitted to the base station at the transmission point, and the electric field strength of the received radio wave is measured at the base station at the reception point. For this purpose, a measuring device for electric field strength is prepared. The reception point and transmission point antennas are alternately swung left and right, and a position with high electrolytic strength is required.

  Further, the height of the antenna at the receiving point is varied up and down, and the displacement of the received electric field strength is measured with a measuring instrument. As a result, it is estimated whether the received radio wave is a direct wave or an indirect wave. The received radio wave is required to be a direct wave. If the displacement of the electric field strength is small, the received radio wave is considered to be a direct wave, and the position of the base station is determined.

  In addition, when the distance between the camera and the monitor is long, a relay base station may be installed as appropriate. The position of the relay base station can also be determined using a field strength measuring device in a similar manner.

  In the conventional system, it is desired that the base stations are arranged as far as possible from the viewpoint of efficient arrangement of the base stations. The above-described electric field strength measuring device is used to determine whether or not the base stations can be further moved away from each other. If the electric field strength is larger than the limit value, the base stations are moved away from each other.

In this regard, the conventional system is installed in various places, and is often installed in a place having a complicated topography such as a mountainous area. In addition, the state of surrounding radio waves that become noise varies depending on the installation location, and there are places where there are very few surrounding radio waves, such as in mountainous areas. Since the distance between base stations that can be communicated varies depending on such various conditions, it is not easy to determine the distance between base stations from a map or the like. Therefore, in the past, as described above, using a measuring instrument, actually measuring the electric field strength, checking whether there is a margin in the electric field strength, and determining whether the distance between base stations can be extended. .
JP 2002-230654 A (3rd page, FIG. 1)

  However, in the past, as described above, in order to determine whether the distance between base stations can be increased, the field strength measuring device is used to actually measure the field strength, which is cumbersome and laborious. It was over. In addition, it was cumbersome to carry the measuring instrument in terms of portability.

  Further, in the conventional system, after the wireless base station is installed, the reception state may deteriorate due to the influence of the external environment, and a reception impossible state may occur. In this case, the monitor on the receiving side continues to output the image recorded in the buffer, and the monitoring image is frozen. However, when monitoring a track along a track, the subject to be photographed is originally a landscape, and there is little movement of the monitoring image even in a normal state, so it is not easy to distinguish between a normal state and a frozen state. Therefore, it takes time to notice the occurrence of the freeze, and it is not easy to quickly deal with the occurrence of the freeze.

  The present invention has been made under the above-described background, and the purpose of the present invention is to make it easy to determine whether or not the distance between base stations can be extended, and to perform radio station monitoring that enables efficient and quick installation of base stations. To provide a system.

  Another object of the present invention is to provide a wireless track monitoring system that can quickly and reliably detect the occurrence of freeze.

  A wireless track monitoring system according to the present invention is a camera that captures a track along a track, a monitor that is installed away from the camera and that displays a monitoring image captured by the camera, and is simply installed along a track along the track. A plurality of portable wireless base station devices that wirelessly transmit monitoring images from the monitor to the monitor, wherein the transmitting wireless base station device includes an attenuation unit disposed between a wireless unit and an antenna, and the attenuation And an extension determination mode setting means for setting an extension determination mode for determining whether or not the distance between base stations can be extended by attenuating the transmission signal, and the attenuation amount of the attenuation means is set as a candidate. It is set according to the distance extension width between base stations. The extension determination mode setting means is preferably configured to be selectively switchable between a normal communication state and a state in which attenuation is performed with respect to the normal communication state, and is configured by, for example, a switch circuit. The normal communication state is a state where attenuation for the above determination is not performed.

  With this configuration, it is possible to determine whether or not the distance between the base stations can be extended by attenuating the transmission signal by the attenuating unit depending on whether or not communication is possible even in the attenuated state. The communication state can be easily determined by, for example, whether or not the monitoring image can be displayed. Moreover, the attenuation amount is set according to the extension width of the candidate inter-base station distance. That is, since the attenuation amount when the extension width of the candidate is extended is predicted, the attenuation amount of the attenuation means is set based on the predicted attenuation amount. Therefore, it can be predicted how much the distance between base stations can be extended. In this way, it becomes easy to determine whether the distance between base stations can be extended, and the base station can be installed efficiently and quickly.

  Moreover, in the wireless trackside monitoring system of the present invention, the attenuation means is configured to be able to switch between a plurality of attenuation amounts set according to different distance extension widths.

  With this configuration, it can be determined with higher accuracy how much the distance between base stations can be increased, and the work efficiency of the base station installation can be further improved.

  Further, in the radio railway monitoring system of the present invention, the transmitting radio base station transmits information on the magnitude of attenuation of the attenuation means to the receiving radio base station, and the receiving radio base station Displays the magnitude of the received attenuation on the monitor.

  With this configuration, since the attenuation setting can be easily understood on the reception side, the convenience in determining installation can be improved.

  Further, in the wireless trackside monitoring system according to the present invention, the transmission-side radio base station apparatus superimposes a predetermined time-varying signal other than the monitoring image that changes with time on the monitoring image captured by the camera. Means.

  With this configuration, since the signal superimposing means for superimposing the time-varying signal on the monitoring image is provided, when the monitoring image freezes, the time-varying signal superimposed on the monitoring image also freezes. And you can find it reliably.

  A wireless track monitoring system according to another aspect of the present invention includes a camera that captures a track along a track, a monitor that is installed away from the camera and that displays a monitoring image captured by the camera, and is simply installed along the track. A plurality of portable wireless base station devices that wirelessly transmit monitoring images from the camera to the monitor, and the wireless base station device on the transmission side adds to the monitoring images captured by the camera as time elapses. Signal superimposing means for superimposing a predetermined time-varying signal other than the monitoring image that changes is provided.

  With this configuration, as described above, it is possible to quickly and reliably find the occurrence of freeze.

  Another aspect of the present invention is a radio base station apparatus that is simply installed outdoors and transmits a monitoring image captured by a camera wirelessly. The apparatus has an attenuation unit disposed between a radio unit and an antenna, and an extension determination mode for determining whether the distance between base stations can be extended by attenuating a transmission signal by the attenuation unit. Extension determination mode setting means for setting, and the attenuation amount of the attenuation means is set according to the distance between base station distance extensions. With this configuration, as described above, it is easy to determine whether the distance between base stations can be extended, and the base station can be installed quickly and efficiently.

  Another aspect of the present invention is a radio base station apparatus that is simply installed outdoors and transmits a monitoring image captured by a camera wirelessly. The apparatus includes a signal superimposing unit that superimposes a predetermined time-varying signal other than the monitoring image that changes with time on the monitoring image captured by the camera. With this configuration, as described above, it is possible to quickly and reliably find the occurrence of freeze.

  Another aspect of the present invention is a base station arrangement method for determining the arrangement of a plurality of radio base stations that are simply installed along a line, and this method can communicate between a radio base station on a transmission side and a reception side. , A step of attenuating the amount of attenuation set according to a candidate for the extension width of the inter-base station distance with respect to the transmission signal of the radio base station on the transmitting side, and And changing the inter-base station distance according to the communication state. Also with this configuration, as described above, it is easy to determine whether or not the distance between base stations can be extended, and the base station can be installed quickly and efficiently.

  As described above, the present invention provides a wireless trackside monitoring system that has the effect of facilitating the determination of whether or not the distance between base stations can be extended, and enabling the base station to be installed efficiently and quickly. Is something that can be done. Further, according to the present invention, it is possible to quickly and reliably find the occurrence of freeze.

  Hereinafter, a wireless railroad monitoring system according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 shows the configuration of the transmission side of the wireless trackside monitoring system according to the first embodiment of the present invention, FIG. 2 shows the configuration of the reception side, and FIG. The overall configuration including the receiving side is shown. The wireless track monitoring system of the present embodiment is simply installed at a disaster site or a construction site along the track.

  First, referring to FIG. 3, the wireless route monitoring system 10 includes a camera 12, a camera turntable 14, a transmission-side radio base station device (hereinafter referred to as a transmission base station) 16, and a reception-side radio base station device (hereinafter referred to as reception). Base station) 18, monitor 20, and controller 22.

  The camera 12, the camera turntable 14, and the transmission base station 16 are installed at a location to be monitored along the track, and the camera 12 and the camera turntable 14 are connected to the transmission base station 16. On the other hand, the receiving base station 18, the monitor 20 and the controller 22 are installed apart from the camera 12 and the like, and the monitor 20 and the controller 22 are connected to the receiving base station 18.

  The camera 12 is a video camera, shoots a monitoring target, and generates a video signal (moving image) of the monitoring image. The camera turntable 14 includes a rotation mechanism, and rotates the camera 12 to change the shooting direction.

  The transmission base station 16 and the reception base station 18 perform wireless communication. For example, 2.4 GHz band spread spectrum wireless communication is performed. The wireless track monitoring system 10 is a temporary system that is simply installed as described above, and the transmission base station 16 and the reception base station 18 are also easily installed using a tripod or the like.

  The monitor 20 is composed of a CRT or the like and displays a monitoring image. The controller 22 includes operation members such as switches and buttons, and receives an instruction for remote operation by an operator. Then, the controller 22 generates a remote control signal in accordance with the operator's instruction.

  In the wireless track monitoring system 10, the monitoring image of the camera 12 is input to the transmission base station 16 and transmitted from the transmission base station 16 to the reception base station 18. Then, the monitoring image is supplied from the receiving base station 18 to the monitor 20 and displayed on the monitor 20. The control signal of the controller 22 is input to the reception base station 18 and transmitted from the reception base station 18 to the transmission base station 16. The control signal is supplied to the camera 12 and the camera turntable 14, and the camera 12 and the camera turntable 14 operate according to the control signal. The control signal is, for example, a signal that instructs the rotation operation of the rotation mechanism of the camera turntable 14.

  As shown in the above description, the transmitting base station 16 and the receiving base station 18 actually perform bidirectional communication. In the present embodiment, paying attention to the monitoring image communication, the side on which the camera 12 is installed is called a transmitting side, and the side on which the monitor 20 is installed is called a receiving side.

  Next, FIG. 1 shows the configuration of the transmission base station 16 (transmitter). The transmission base station 16 includes a character generator 30, a digital conversion unit 32, and an image compression unit 34 for processing the image signal, and also includes a digital conversion unit 34 for processing the control signal. . The image compression unit 34 and the digital conversion unit 36 are connected to the multiplexing unit 40, and the wireless unit 42, the switching unit 44, the attenuation mechanism 46, and the antenna 48 are sequentially connected to the multiplexing unit 40. Further, a switching operation unit 50 is connected to the switching unit 44.

  The character generator 30 generates a time code (time information) in units of 100 msec, and superimposes the time code on the input image signal from the camera 12. The digital conversion unit 32 converts the analog image signal on which the time code is superimposed into digital image data. The image compression unit 34 compresses and encodes digital image data.

  On the other hand, a control signal is input to the digital conversion unit 36 from the camera 12 and the camera turntable 14. The digital conversion unit 36 performs digital conversion of the control data and generates digital format data.

  The multiplexing unit 40 multiplexes the compressed image data and the control data. The radio unit 42 generates a transmission signal from the multiplexed data. The transmission signal is transmitted from the antenna 48 via the switching unit 44 and the attenuation unit 46. The switching unit 44, the attenuation unit 46, and the switching operation unit 50 will be described later.

  Regarding the reception function, the antenna 48 receives radio waves including control data. The wireless unit 42 performs wireless data reception processing. The multiplexing unit 40 obtains control data by performing demultiplexing processing on the received data. The digital conversion unit 36 converts the control data into an analog signal.

  Next, FIG. 2 shows the configuration of the receiving base station 18 (receiver). In the receiving base station 18, an antenna 60, a radio unit 62, and a multiplexing unit 64 are sequentially connected. The multiplexing unit 64 is connected to an image expansion unit 70 and an image reproduction unit 72 for processing an image signal, and is connected to a digital conversion unit 74 for processing a control signal.

  The wireless unit 62 performs wireless data reception processing on the reception signal received by the antenna 60. The multiplexing unit 64 performs demultiplexing processing on the received data and separates into compressed image data and control data. The image decompression unit 70 decompresses the compressed image data. The image reproduction unit 72 includes a digital conversion unit and reproduces a video signal from the expanded image data. The video signal is supplied to the monitor 20.

  The digital conversion unit 74 converts the control data into an analog signal. The converted control signal is supplied to the controller 22.

  Regarding the transmission function, the digital conversion unit 74 converts the control signal from the controller 22 into digital format data. This control data is supplied to the radio unit 62 via the multiplexing unit 64. The radio unit 62 generates a transmission signal, and the transmission signal is transmitted from the antenna 60.

  The transmitted control data is data indicating a remote operation instruction as described above. On the other hand, the control data received by the receiving base station 18 is data indicating responses of the camera 12 and the camera turntable 14 to the instruction from the controller 22.

  Next, FIG. 4 conceptually shows the configuration of the switching unit 44, the attenuation unit 46, and the switching operation unit 50. The attenuation unit 46 has three bypass paths 82, 84, 86 in parallel with the main path 80. The three bypass paths 82, 84, and 86 are provided with attenuation circuits 90, 92, and 94 that are configured by resistors, respectively. The switching unit 44 is configured by a switch circuit, and connects the radio unit 42 to any one of the main path 80 and the bypass paths 82, 84, 86. The switching operation unit 50 includes a dial or the like and is manually operated by an operator. The switching operation unit 50 is connected to the switching unit 44. Then, according to the operation of the switching operation unit 50, the switch of the switching unit 44 is switched.

  The switching unit 44 is configured to be able to selectively switch between a normal communication state in which attenuation is not performed and a state in which attenuation is performed with respect to the normal communication state, thereby extending the distance between base stations. It functions as a means for setting an extension determination mode for determining whether or not. The inter-base station distance is the distance between the transmitting base station 16 and the receiving base station 18. When the wireless unit 42 is connected to the attenuation circuits 90, 92, and 94 by the switching unit 44, the extension determination mode is set. In the extension determination mode, the transmission signal is attenuated. It can be seen that even if the transmission signal is attenuated, the distance between base stations can be extended if the communication state is good.

  FIG. 5 shows the setting of attenuation amounts of the attenuation circuits 90, 92, and 94. The attenuation amount is set according to the extension width of the candidate inter-base station distance as described below.

  In FIG. 5, the horizontal axis represents the distance between base stations (m), and the vertical axis represents the reception level (reception field strength) (dB). The reception level is inversely proportional to the square of the distance between base stations in free space (FIG. 5 uses a logarithm, so the relationship between the distance and the reception level is represented by a straight line). Therefore, by referring to the relationship of FIG. 5, it can be predicted how much the signal will be attenuated by extending the distance between the base stations. It is assumed that the reception state is good even when the expected attenuation is generated. In this case, even if the extension width corresponding to the attenuation amount is actually extended, it is considered that the reception state is still good. Based on such a principle, the amount of attenuation is set.

  As illustrated, in the present embodiment, the attenuation amounts of the attenuation circuits 90, 92, and 94 are set to -3 dB, -6 dB, and -9 dB. In the 2.4 GHz band communication, the attenuation amounts −3 dB, −6 dB, and −9 dB correspond to the extended widths of 1.4 times, 2 times, and 2.7 times in the free space, respectively. The resistance values of the attenuation circuits 90, 92, and 94 are set so that such an attenuation amount can be obtained.

  Further, the wireless railway monitoring system 10 of the present embodiment is configured to send the setting information for attenuation amount switching in the extension determination mode from the transmission side to the reception side. That is, a control unit (not shown) of the transmission base station 16 monitors the switching state of the switching unit 44. When the extension determination mode is set, the control unit sends information about the set amount of attenuation to the character generator 30. The character generator 30 superimposes a character having a magnitude of attenuation (for example, −6 dB) on the image signal from the camera 12. This image signal is transmitted from the transmission base station 16 to the reception base station 18 and displayed on the monitor 20. Thus, in the present embodiment, attenuation information is sent from the transmission side to the reception side by superimposing it on the image. However, the present invention is not limited to the above configuration, and attenuation information may be sent without being superimposed on an image within the scope of the present invention.

  Next, a method for determining the base station arrangement in the radio railway monitoring system 10 according to the present embodiment will be described. First, the transmission base station 16 and the reception base station 18 are installed by the same method as before. That is, the positions of the reception point and the transmission point are selected so that a line of sight from the reception point to the transmission point can be secured using a mirror, a laser, or the like. Next, the antenna 48 of the transmission base station 16 and the antenna 60 of the reception base station 18 are arranged to face each other. The transmitting base station 16 transmits a certain radio wave, and the receiving base station 18 checks the reception state. For this operation, although not shown, the receiving base station 18 includes a simple electric field strength measuring device as provided in a mobile phone. The antenna 60 at the reception point and the antenna 48 at the transmission point are alternately swung to the left and right to obtain a position with high electrolytic strength. Further, the height of the antenna 60 at the receiving point is varied up and down to examine the displacement of the received electric field strength. This confirms that the received radio wave is a direct wave.

  The above operation is performed in a normal state in which the attenuation unit 46 does not perform attenuation. Next, the switching operation unit 50 of the transmission base station 16 is operated by the operator. The switching unit 44 performs a switching operation according to the operation, and any one of the attenuation circuits 80, 82, 84 is connected to the wireless unit 42. Thereby, the extension determination mode is set.

  In this state, transmission and display of the monitoring image are attempted. Further, remote control is attempted by operating the controller 22. The remote control is, for example, rotation of the camera 12 by the camera turntable 14. If the image is displayed on the monitor 20 and the camera 12 can be remotely operated, the operator determines that the reception state in the attenuation state is good, and only the extension width corresponding to the attenuation amount. Judge that the distance between base stations can be extended.

  As already described, when the extension determination mode is set, attenuation setting information is superimposed on the image signal by the character generator 30 on the transmission side. Thereby, the magnitude of the attenuation is sent from the transmission side to the reception side. On the receiving side, the attenuation amount (for example, −6 dB) is displayed on the monitor 20, so that the setting of the attenuation amount can be easily understood.

  The attenuation amount in the extension determination mode is selected by the operator. As described with reference to FIG. 5, when the attenuation circuit 80 is selected, the attenuation amount is −3 dB. If the communication state is good, the distance between base stations can be increased by 1.4 times in free space. Similarly, when the attenuation circuit 82 is selected, the amount of attenuation is −6 dB, and if the communication state is good, the distance between base stations can be doubled in free space. Furthermore, when the attenuation circuit 84 is selected, the amount of attenuation is −9 dB, and if the communication state is good, the distance between base stations can be 2.7 times in free space. The attenuation amount may be sequentially switched, and the communication state at each attenuation amount may be confirmed. Thereby, it can be determined how much extension is possible.

  When it is found that extension is possible in the extension determination mode, the distance between base stations is expanded within the range of the extension width corresponding to the attenuation. Then, the above setting operation is performed again. If the reception state can be established, the arrangement of the base stations is determined. Note that, from this state, the determination as to whether or not the extension can be performed may be performed again.

  Next, image transmission and display operations after the base station is installed will be described. The camera 12 supplies a monitoring image signal along the line to the transmission base station 16. In the transmission base station 16, the time code is superimposed on the input video signal by the character generator 30. The time code is generated in units of 100 msec. The image signal on which the time code is superimposed is converted into digital data by the digital conversion unit 32, compressed by the image compression unit 34, and supplied to the multiplexing unit 40. Further, control data is supplied from the digital conversion unit 36 to the multiplexing unit 40. Image data and control data are multiplexed by the multiplexing unit 40, and a transmission signal is generated from the multiplexed data by the radio unit 42. The transmission signal is transmitted from the antenna 48 through the switch unit 44 and the attenuation unit 46. At this time, the switch unit 44 is switched so that the attenuation unit 46 does not attenuate the transmission signal.

  In the reception base station 18, the radio unit 62 performs radio data reception processing on the reception signal received by the antenna 60 to obtain reception data. The received data is divided into image data and control data by the multiplexing unit 64. The control data is sent to the controller 22 via the digital conversion unit 74. The image data is expanded by the image expansion unit 70. Then, a video signal is reproduced by the image reproduction unit 72 from the decompressed image data. Then, the video signal is supplied to the monitor 20. As a result, the monitor image is displayed on the monitor 20.

  As described above, a time code is superimposed on the monitoring image on the transmission side. Therefore, time is displayed on the monitoring image, and the image of the time portion changes with time.

  Next, image freeze when the reception state deteriorates will be described. As described in the background art, the wireless route monitoring system 10 is simply installed in various places such as a plain part and a mountain part. Unlike a permanent system, temporary installation is performed, so the installation environment is not always confirmed. For this reason, after the wireless base station is installed, the reception state may deteriorate due to the influence of the external environment, and a reception impossible state may occur. Further, since the radio base station itself is simply installed, the attitude change may occur and the reception state may deteriorate.

  When the reception state deteriorates, a past image is read from the buffer memory on the reception side and displayed on the monitor 20. Such a system configuration is advantageous for deterioration of reception conditions in a very short time. However, since such a system configuration is employed, when a reception impossible state occurs, the monitor 20 continues to display a still image and enters a frozen state.

  However, when monitoring along the track, the object to be photographed is originally a landscape, and there is little movement of the monitoring image even in a normal state. Therefore, it is not easy to notice the occurrence of freeze in the past.

  However, in this embodiment, the time code is superimposed. The time code always changes in the normal state. On the other hand, when the freeze occurs, the time code time display stops. Therefore, the normal state and the frozen state can be determined depending on whether or not the time display is stopped. The operator looks at the monitor 20 and determines that the freeze has occurred when the time display is stopped.

  Next, FIG. 6 shows a system configuration example in the case where a plurality of cameras and a transmission base station are provided. In FIG. 6, cameras 100, 102, and 104 are installed together with transmission base stations 110, 112, and 114, respectively. The transmitting base stations 110, 112, and 114 move away from the receiving base station 120 in this order.

  The transmission base stations 110, 112, and 114 function in the same manner as in the above-described embodiment. Further, the transmission base stations 110 and 112 are configured to function as relay base stations. That is, the monitoring image of the camera 104 is transmitted from the transmission base station 114, relayed by the transmission base station 112 and the transmission base station 110, and received by the reception base station 120. The monitoring image of the camera 102 is transmitted from the transmission base station 112, relayed by the transmission base station 110, and received by the reception base station 120.

  In the receiving base station 120, the controller 122 is operated to switch the image of the monitor 124, and any of the images of the cameras 100, 102, and 104 is displayed.

  In the system of FIG. 6, the arrangement of each base station is performed according to the method described above. For example, first, the arrangement of the receiving base station 120 and the transmitting base station 110 is determined. At this time, the transmission base station 110 sets an extension determination mode to determine whether extension is possible. Whether or not the image can be extended is determined based on whether or not an image can be displayed on the monitor 124. Then, the base station arrangement is determined based on the determination result.

  Next, the position of the transmission base station 112 is determined. Here, the arrangement is determined so that the communication state between the transmission base station 112 and the transmission base station 110 is ensured. At this time, the transmission base station 112 sets an extension determination mode to determine whether extension is possible. Here again, whether or not the image can be extended is determined depending on whether or not an image can be displayed on the monitor 124. Then, the base station arrangement is determined based on the determination result. The arrangement of the transmission base station 114 is determined in the same manner.

  Thus, even if there are a plurality of transmission base stations, the base station arrangement can be determined by the same method with the same configuration as that of the above-described embodiment.

  In the present embodiment, the transmission base stations 110 and 112 function not only as transmitters but also as relay base stations. If the cameras 100 and 102 are removed, the transmission base stations 110 and 112 function only as relay base stations. Further, a simple relay base station may be provided instead of the transmission base stations 110 and 112. In this case, for extension of the distance between base stations, it is determined whether or not the distance between the transmission base station and the relay base station can be extended.

  Regarding freeze detection, the transmission base stations 110, 112, and 114 superimpose time codes on the monitoring images of the cameras 100, 102, and 104, respectively. Therefore, the occurrence of the freeze state can be detected from the image on the monitor 124 in the same manner as in the above-described embodiment.

  The radio railway monitoring system 10 according to the preferred embodiment of the present invention has been described above. According to the present embodiment, by setting the extension determination mode for attenuating the transmission signal, it can be determined whether or not the distance between the base stations can be extended depending on whether or not communication is possible even in the attenuated state. In addition, the attenuation amount is set according to the extension width of the distance between the base stations as candidates, so that it can be predicted how much the distance between the base stations can be extended. In this way, it becomes easy to determine whether the distance between base stations can be extended, and the base station can be installed efficiently and quickly.

  Moreover, in this Embodiment, the transmission base station 16 is comprised so that switching of the some attenuation amount set according to each different distance extension width is possible. Thereby, it can be judged with higher accuracy how much the distance between base stations can be increased, and the work efficiency of the base station installation can be further improved.

  In the present embodiment, information on the magnitude of attenuation on the transmission side is sent to the reception side and displayed on the monitor on the reception side. In the present embodiment, the attenuation amount is superimposed on the monitoring image and transmitted on the transmission side. By displaying the attenuation amount on the monitor at the reception side in this way, the attenuation setting can be easily understood at the reception side without separately transmitting the attenuation setting from the transmission side to the reception side. Convenience in judgment can be improved.

  In the present embodiment, a predetermined time-varying signal other than the monitoring image that changes with time is superimposed on the monitoring image captured by the camera. As a result, occurrence of freeze can be detected quickly and reliably.

  The time-varying signal is a time code in the present embodiment. The time code is also used in commercially available video cameras. However, in a video camera, the time code is a signal recorded on the tape separately from the image. In contrast, in the present embodiment, the time code is superimposed on the monitoring image at the transmission stage. By this superimposition processing, the freeze state as described above can be detected.

  Further, the time-varying signal is not limited to the time code within the scope of the present invention. The time-change signal may be another signal as long as it changes with time. For example, the temporal change signal may be an image signal of a character such as an icon. Moreover, the speed of change should just be the range which can determine a freeze easily. Further, the time-change signal may be a signal that periodically degrades or changes the color of the image.

  Further, the configurations of the attenuation unit 46 and the switching unit 44 are not limited to the above-described embodiment. The attenuation unit 46 and the switching unit 44 may be configured by variable resistors. Further, the attenuation unit 46 and the switching unit 44 may be realized by other types of circuits.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and it goes without saying that those skilled in the art can modify the above-described embodiments within the scope of the present invention.

  As described above, the wireless route monitoring system according to the present invention has an effect that the installation work of the base station can be performed efficiently and quickly, and is useful as a track monitoring system in a disaster site or the like.

The block diagram which shows the structure by the side of the transmission of the radio railway monitoring system in embodiment of this invention The block diagram which shows the structure of the receiving side of the radio track monitoring system in embodiment of this invention The block diagram which shows the whole structure of the radio railway monitoring system in embodiment of this invention The figure which shows the structure of the attenuation part and switching part of a transmission base station The figure which shows the example of a setting of the attenuation amount of an attenuation part

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Radio along-line monitoring system 12 Camera 14 Camera turntable 16 Transmission base station 18 Reception base station 20 Monitor 22 Controller 30 Character generator 42 Radio | wireless part 44 Switching part 46 Attenuation mechanism 48 Antenna 50 Switching operation part 90, 92, 94 Attenuation circuit

Claims (8)

A camera that shoots along the tracks,
A monitor installed away from the camera and displaying a monitoring image taken by the camera;
A plurality of portable radio base station devices that are simply installed along the line and send a monitoring image wirelessly from the camera to the monitor;
The transmitting-side radio base station apparatus includes: attenuating means disposed between the radio unit and the antenna; and whether the attenuating means attenuates the transmission signal to thereby extend the distance between base stations. An extension determination mode setting means for setting an extension determination mode for determination, wherein the attenuation amount of the attenuation means is set in accordance with a distance extension width between base stations as candidates. Monitoring system.   The wireless railroad monitoring system, wherein the attenuation means is configured to be able to switch a plurality of attenuation amounts set according to different distance extension widths.   The transmitting-side radio base station transmits information on the magnitude of attenuation of the attenuation means to the receiving-side radio base station, and the receiving-side radio base station sets the received magnitude of attenuation to the The wireless trackside monitoring system according to claim 1, wherein the system is displayed on a monitor.   The transmission-side radio base station apparatus includes signal superimposing means for superimposing a predetermined time-varying signal other than a monitoring image that changes with time on a monitoring image captured by a camera. The wireless trackside monitoring system according to any one of 1 to 3. A camera that shoots along the tracks,
A monitor installed away from the camera and displaying a monitoring image taken by the camera;
A plurality of portable radio base station devices that are simply installed along the line and send a monitoring image wirelessly from the camera to the monitor;
And the transmission-side radio base station apparatus includes a signal superimposing unit that superimposes a predetermined time-varying signal other than the monitoring image that changes with time on the monitoring image captured by the camera. A wireless line monitoring system. A wireless base station device that is simply installed outdoors and wirelessly transmits a monitoring image taken by a camera,
Attenuation means arranged between the radio unit and the antenna, and an extension judgment mode for setting an extension judgment mode for judging whether or not the distance between base stations can be extended by attenuating a transmission signal by the attenuation means A radio base station apparatus comprising: a mode setting unit, wherein an attenuation amount of the attenuation unit is set according to a distance extension width between base stations as candidates. A wireless base station device that is simply installed outdoors and wirelessly transmits a monitoring image taken by a camera,
A radio base station apparatus comprising signal superimposing means for superimposing a predetermined time-varying signal other than a monitoring image that changes with time on a monitoring image captured by a camera. A base station arrangement method for determining the arrangement of a plurality of radio base stations that are simply installed along a track,
Arranging the transmitting side and the receiving side radio base stations in a communicable position;
Attenuating an attenuation amount set according to a candidate for the extension width of the inter-base station distance with respect to the transmission signal of the transmitting radio base station;
Changing the distance between base stations according to the communication state in the attenuated state;
A base station arrangement method characterized by comprising:

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