Train radio system

Abstract

This system enables a low-cost train radio system where onboard radios installed on trains can reliably communicate with ground-based radios at each station. [Solution] A train radio system according to one embodiment of the present invention comprises an onboard radio 10 mounted on a train and ground radios 20 installed at each station along the train's route. The onboard radio 10 is equipped with a rotatable antenna 12 used for wireless communication with the ground radios 20, and rotates the antenna 12 before the train reaches the next station based on next station data for identifying an antenna direction suitable for wireless communication at the train's next stop.

Description

Technical Field

[0001] The present invention relates to a train wireless system in which an on-train radio installed on a train performs wireless communication with a ground radio at each station.

Background Art

[0002] Conventionally, an image transmission system has been developed that transmits a platform image (hereinafter simply referred to as "platform") of a station where a train stops to the train side and displays it on an on-train monitor in the driver's cab. In the image transmission system, the platform image is transmitted by wireless communication between a ground radio installed at each station and an on-train radio installed on the train.

[0003] Examples of the prior art in the technical field related to the present invention include the following. For example, Patent Document 1 discloses that a base station that is not a communication partner of a mobile station transmits a radar signal but does not transmit a communication signal, and a base station that has become a communication partner of the mobile station transmits a radar signal and a communication signal simultaneously. Patent Document 2 discloses performing data transmission and stop determination of a mobile body using wireless communication between the mobile body side and the fixed side.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] Generally, onboard radios are installed and fixed in place at their designated locations on the train. Ground radios at each station are installed after prior consideration of a location that allows for stable radio communication with onboard radios on trains stopped at that station. For example, if the onboard radio is installed on the front or rear car of the train, it is desirable that the ground radio be installed near the stopping position of the front or rear car on the station platform. Furthermore, it is desirable that the antenna of the onboard radio be oriented towards the antenna of the ground radio when the train is stopped at a station.

[0006] However, because the shape of the platforms and space constraints differ from station to station, the relative positions of the on-board radio and the ground radio are not the same at all stations. As a result, some stations will have less margin for receiving power for the on-board and ground radios. In addition, the installation location of the ground radio, which can reliably communicate with the fixed on-board radio, is limited, requiring fine adjustments to the position of the ground radio, which increases the cost of preliminary surveys and studies.

[0007] This invention has been made in view of the above-mentioned conventional circumstances, and aims to realize a low-cost train radio system that enables onboard radio equipment mounted on trains to reliably communicate with ground radio equipment at each station. [Means for solving the problem]

[0008] A train radio system according to one aspect of the present invention is a train radio system comprising an onboard radio mounted on a train and ground radios installed at each station in the section of the train's route, wherein the onboard radio is equipped with a rotatable antenna used for wireless communication with the ground radios, and rotates the antenna before the train reaches the next station based on next station data for identifying an antenna direction suitable for wireless communication at the next station the train will stop at.

[0009] In the above-described train radio system, the onboard radio may be configured to receive the next station data via wireless communication with a ground radio at the station immediately preceding the next stop.

[0010] Furthermore, in the above-described train radio system, the onboard radio may be configured to rotate its antenna after the radio communication with the ground radio at the station immediately preceding the next stop is disconnected.

[0011] Furthermore, in the above-described train radio system, the next station data may be configured to include information indicating the direction of the ground radio as seen from the onboard radio when the train stops at the next station.

[0012] Furthermore, in the above-described train radio system, the next station data may be configured to include information indicating the position of the ground radio at the next station, based on the position of the onboard radio when the train stops at the next station. [Effects of the Invention]

[0013] According to the present invention, a train radio system can be realized at low cost that enables onboard radio equipment installed on trains to reliably communicate with ground radio equipment at each station. [Brief explanation of the drawing]

[0014] [Figure 1] This figure shows an overview of a train radio system according to one embodiment of the present invention. [Figure 2] Figure 1 shows an example of the data flow related to adjusting the antenna direction of the onboard radio in the train radio system. [Figure 3] Figure 1 shows an example of the processing flow related to adjusting the antenna direction of the onboard radio in the train radio system. [Modes for carrying out the invention]

[0015] One embodiment of the present invention will be described with reference to the drawings. Figure 1 shows an overview of a train radio system according to one embodiment of the present invention. The train radio system in this example has an onboard radio 10 mounted on the train and ground radios 20 installed at each station along the train's route. In the example shown in Figure 1, ground radio 20-1 is installed at station A, the train's current stop, and ground radio 20-2 is installed at station B, the next stop.

[0016] The onboard radio 10 is installed, for example, in the leading and / or trailing cars of the train. The ground radio 20 is installed, for example, near the stopping positions of the leading and / or trailing cars of the train on the station platform, so that stable radio communication can be established with the onboard radio 10 of the train when it is stopped at a station. In other words, the ground radio 20 may be installed near the up-bound end and / or down-bound end of the station platform.

[0017] The antenna 12 of the onboard radio 10 is a directional antenna that has directivity in a specific direction and range. In other words, the antenna 12 of the onboard radio 10 needs to be positioned so that it is directional towards the antenna 22 of the ground radio 20 when the train stops at a station. However, because the shape of the platform and space constraints differ from station to station, the relative positions of the onboard radio 10 and the ground radio 20 may change from station to station. As a result, the antenna 12 of the onboard radio 10 may not be properly oriented towards the antenna 22 of the ground radio 20, which could result in some stations having less margin for received power in the onboard radio 10 and the ground radio 20. Countermeasures for this problem are described below.

[0018] In this example of a train radio system, the antenna 12 of the onboard radio 10 is mounted on the base of an antenna rotating base 14 fixed at a predetermined position on the vehicle. The antenna rotating base 14 has a mechanism that rotates its base horizontally according to control from the onboard radio 10. Therefore, by rotating the base of the antenna rotating base 14, it is possible to change the azimuth angle of the antenna 12 mounted on the base.

[0019] Fig. 2 shows an example of the data flow related to the adjustment of the antenna direction of the on-vehicle radio 10 in the train radio system of this example. When the train stops at a station, millimeter-wave wireless communication is performed between the on-vehicle radio 10 of the train and the ground radio 20 of the stopped station. Using this millimeter-wave wireless communication, the home image captured by the camera installed at the stopped station is transmitted to the train side and displayed on the on-vehicle monitor 16 in the train's driver's cab. Also, the door image and the in-vehicle image captured by the camera attached to each vehicle of the train are transmitted to the station side and displayed on a ground monitor (not shown) in the station staff room of the stopped station.

[0020] Furthermore, using the millimeter-wave wireless communication, the next-station data is transmitted from the ground radio 20 of the stopped station to the on-vehicle radio 10. The next-station data is data for specifying the antenna direction suitable for wireless communication at the next stop station of the train, and is stored in advance in the ground radio 20 or a device associated with it. In the example of Fig. 2, as the next-station data, installation position data indicating the position (i.e., relative position) of the ground radio of the next stop station based on the position of the on-vehicle radio when the train stops at the next stop station is used. Note that other forms of data, such as installation azimuth data indicating the azimuth (i.e., relative azimuth) of the ground radio as seen from the on-vehicle radio when the train stops at the next stop station, can also be used as the next-station data.

[0021] Note that since the next stop station is different depending on whether the train's traveling direction is the uphill direction or the downhill direction, the content of the next station data will also be different. Therefore, before transmitting the next station data, the ground radio unit 20 needs to identify the train's traveling direction, but the method is arbitrary. For example, when the arrival track is different according to the train's traveling direction, the ground radio unit 20 can identify the train's traveling direction based on the train's arrival track. Also, the ground radio unit 20 may identify the train's traveling direction based on operation information obtained from the train operation management system or the like. Further, the ground radio unit 20 may receive information on the traveling direction from the train side (the on-vehicle radio unit 10) and identify the train's traveling direction. Also, the ground radio unit 20 may identify the train's traveling direction using information obtained by an external device such as a radar installed on the station platform. Also, when the ground radio unit 20 is installed near each of the end portions on the uphill direction side and the end portions on the downhill direction side of the station platform, the train's traveling direction may be identified according to which side's ground radio unit 20 has first become capable of wireless communication with the on-vehicle radio unit 10.

[0022] The on-vehicle radio unit 10 stores the next station data received from the ground radio unit 20 in a memory (not shown), and transmits rotation control data based on the next station data to the antenna turntable 14 at a predetermined timing, thereby rotating (changing the azimuth angle) the antenna 12 attached to the antenna turntable 14. The timing of antenna rotation is any timing between the point when image transmission at the current stop station (for example, station A) becomes unnecessary and the point when image transmission at the next stop station (for example, station B) becomes necessary. For example, it is set to start antenna rotation in the on-vehicle radio unit 10 at the timing when the wireless communication related to image transmission at the current stop station is disconnected. Also, the antenna rotation in the on-vehicle radio unit 10 may be started in response to an instruction from the train driver or the crew.

[0023] In this case, if the installation location data is used as the next station data, the onboard radio 10 compares the azimuth angle calculated from the installation location data received at the previous station (i.e., the relative position of the ground radio at the current station) with the azimuth angle calculated from the installation location data received at the current station (i.e., the relative position of the ground radio at the next station), calculates the rotation direction and amount to change the antenna direction from one suitable for wireless communication at the current station to one suitable for wireless communication at the next station, and transmits rotation control data including these rotation direction and amount to the antenna turntable 14.

[0024] Furthermore, if the installation direction data is used as the next station data, the onboard radio 10 compares the azimuth angle represented by the installation direction data received at the previous station (i.e., the relative direction of the ground radio at the current station) with the azimuth angle represented by the installation direction data received at the current station (i.e., the relative direction of the ground radio at the next station), calculates the rotation direction and amount to change from the antenna direction suitable for wireless communication at the current station to the antenna direction suitable for wireless communication at the next station, and transmits rotation control data including these rotation direction and amount to the antenna turntable 14.

[0025] Furthermore, if data other than installation location data and installation orientation data is used as next station data, the onboard radio 10 should perform calculations according to the data format to calculate the rotation direction and amount necessary to change the antenna direction from one suitable for wireless communication at the current station to one suitable for wireless communication at the next station, and then transmit rotation control data including these rotation direction and amount to the antenna turntable 14.

[0026] Figure 3 shows an example of the processing flow related to adjusting the antenna direction of the onboard radio 10 in the train radio system of this example. Here, we will explain using the operation when the train stops at station A as an example. The onboard radio 10 receives next station data from the ground radio 20-1 at station A, which is the current station (step S11). Next, based on the received next station data, the onboard radio 10 compares the antenna direction at the current station with the antenna direction at the next station to determine whether or not adjustment of the antenna direction is necessary (step S12).

[0027] If the antenna direction at the current station and the antenna direction at the next station are substantially the same (the difference in antenna direction is less than or equal to a reference value), the onboard radio 10 determines that no adjustment of the antenna direction is necessary (step S12; No), and terminates the process. On the other hand, if the antenna direction at the current station and the antenna direction at the next station are not substantially the same, the onboard radio 10 determines that adjustment of the antenna direction is necessary (step S12; Yes), and waits until the radio communication at the current station is disconnected (step S13). After that, the onboard radio 10 transmits rotation control data based on the next station data to antenna rotation 14, and rotates the antenna 12 (changes the azimuth angle) so that it faces the antenna direction at the next station (step S14).

[0028] As described above, the train radio system in this example comprises an onboard radio 10 mounted on the train and ground radios 20 installed at each station along the train's route. The onboard radio 10 is equipped with a rotatable antenna 12 used for wireless communication with the ground radios 20, and is configured to rotate the antenna 12 before the train reaches the next station based on next-station data to determine the optimal antenna direction for wireless communication at the next station. Therefore, even if the relative positions of the onboard radio 10 and the ground radios 20 differ at each station, stable wireless communication can be achieved. Furthermore, the increased flexibility in the installation position of the ground radios 20 eliminates the need for fine-tuning of the ground radio 10's position, reducing the costs associated with preliminary surveys and studies, and enabling the implementation of a train radio system at a low cost.

[0029] In the above explanation, the onboard radio 10 is configured to receive next-station data to determine the antenna direction suitable for radio communication at the train's next stop through radio communication with the ground radio 20 at the station immediately preceding the next stop, but this is only one example. For example, the onboard radio 10 or its associated equipment may store a list of station data regarding antenna directions at each station in the train's route. Then, the ground radio 20 at the train's current stop may transmit identification information for the next stop to the onboard radio 10, and the onboard radio 10 may refer to the station data list based on the received identification information for the next stop to determine the antenna direction at the next stop. Alternatively, the onboard radio 10 may obtain identification information for the next stop from the train and refer to the station data list based on the identification information to determine the antenna direction at the next stop.

[0030] Furthermore, in the above description, the onboard radio 10 is configured to change the azimuth angle of the antenna 12 based on the next station data, but it may also be configured to change the elevation angle of the antenna. In this case, the antenna rotating base 14 needs to have a mechanism to change the elevation angle of the antenna according to the control from the onboard radio 10.

[0031] Furthermore, the number of train cars may increase or decrease depending on the route, in which case the relative positions of the onboard radio 10 and the ground radio 20 will change even at the same station. Therefore, the onboard radio 10 or the ground radio 20 (or the devices or systems associated with them) may be equipped with a mechanism to adjust the next station data according to the number of train cars. For example, next station data may be prepared for a standard number of train cars, and the next station data for the standard number of train cars may be corrected according to the amount of change in the position of the onboard radio 10 due to an increase or decrease in the number of train cars. Alternatively, next station data may be prepared for each number of train cars, and the next station data corresponding to the number of cars of the target train may be selected. Or, the system may handle increases or decreases in the number of train cars using a mechanism other than those described above.

[0032] Although embodiments of the present invention have been described above, these embodiments are merely illustrative and do not limit the technical scope of the present invention. The present invention can take many other embodiments, and various modifications such as omissions and substitutions can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention as described herein, and are included in the scope of the invention and its equivalents as described in the claims.

[0033] Furthermore, the present invention can be provided not only as the devices described above or as systems composed of such devices, but also as methods executed by these devices, programs for a processor to realize the functions of these devices, and storage media for storing such programs in a computer-readable manner. [Industrial applicability]

[0034] This invention can be used in a train radio system in which onboard radios installed on trains communicate with ground radios at each station. [Explanation of Symbols]

[0035] 10: Onboard radio, 12: Antenna, 14: Antenna rotating stand, 16: Onboard monitor, 20 (20-1, 20-2): Ground radio, 22: Antenna

Claims

1. In a train radio system having an onboard radio installed on a train and ground radios installed at each station along the train's route, The train radio system is characterized in that the onboard radio is equipped with a rotatable antenna used for wireless communication with a ground radio, and the antenna is rotated before the train reaches the next station based on next station data for determining an antenna direction suitable for wireless communication at the next station of the train.

2. In the train radio system according to claim 1, The train radio system is characterized in that the onboard radio receives the next station data by radio communication with a ground radio at the station immediately preceding the next station.

3. In the train radio system according to claim 1, The train radio system is characterized in that the onboard radio rotates its antenna after the radio communication with the ground radio at the station immediately preceding the next stop is disconnected.

4. In the train radio system according to claim 1, A train radio system characterized in that the next station data includes information indicating the direction of the ground radio as seen from the onboard radio when the train stops at the next station.

5. In the train radio system according to claim 1, The train radio system is characterized in that the next station data includes information indicating the position of the ground radio at the next station, based on the position of the onboard radio when the train stops at the next station.

Images