A transmitter/receiver for train detection

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a method for detecting a train in a block section using a track circuit, and particularly to a method for detecting a train, which is capable of maintaining the safety even in the event of failure of a transmission path.

Description of the Related Art

A conventional railway system employs a method, which uses a track and detects the existence of a train in a block section. In such a method, a track is electrically divided into plural sections, each having a predetermined length. Such a section forms a part of an electric circuit, which is called a track circuit, therefore. At both ends of the track circuit, there are arranged transmitter/receiver devices, one of which transmits a signal for detecting a train continuously or at a constant time interval and the other receives the signal.

If a train does not exist in a track circuit, a signal transmitted by a unit on the transmitting side can reach a unit on the receiving side. If, however, a train exists in the track circuit, a signal transmitted by a unit on the transmitting side does not reach a unit on the receiving side, because a pair of rails of the track circuit are short-circuited by wheels of the train. Thereby, the existence of a train can be detected.

In detecting the existence of a train, the high reliability is required, because a control device on the ground (a wayside controller) utilizes a train detective signal generated as above to locate a train and to operate traffic signals. Particularly, for the purpose of securing the safety in the train-service, the following situation must be absolutely avoided to occur: that is, although a train actually exists within a certain track circuit and therefore a pair of rails of the track are short-circuited, a signal indicating no train in the track circuit is erroneously transmitted, due to any failure in a transmitter/ receiver device, for example.

Conventionally, to solve such problem, highly reliable equipment has been used for a transmitter/receiver device installed in every track circuit as well as for a wayside controller. When any trouble occurs in transmitting or receiving, the control is carried out as follows: i.e., the control that no signal is transmitted is done on the transmitting side, and the control judging that no signal is received is done on the receiving side.

In the conventional system as mentioned above, a large number of the transmitter/receiver devices must be subject to the very careful maintenance. Further, an individual signal cable is used for the connection between every transmitter/receiver device and the wayside controller, in order to avoid the misrecognition of information among the devices each other.

Furthermore, JP-A 6-92232 discloses that the signal, which has the different frequency for every track circuit, is used in order to avoid erroneously receiving a train detective signal from an adjacent track circuit.

To sum up, as described above, when any trouble occurs in transmitting or receiving, the prior art carries out the control in such a manner that if the trouble occurs on the transmitting side, no signal is transmitted and if it occurs on the receiving side, it is judged that no signal is received. To this end, highly reliable devices must be utilized for a transmitter/receiver device. As a result, the transmitter/receiver device became complicated in its structure and therefore could not be made small in size.

Since such device is needed for every track circuit, the total system becomes extremely high at its cost. Further, in order that a transmitter/receiver device can achieve the above mentioned control, it must be sufficiently maintained and inspected. Such maintenance and inspection work are very troublesome, since the work must be done for every one of a large number of devices arranged along a wayside.

Further, the technology disclosed in JP-A-6-92232 might have the effect to avoid erroneously receiving of a train detective signal from an adjacent track circuit. However, it cannot solve the problem of being high at cost, due to the complicatedness of the system construction which is needed for maintaining the reliability of a transmitter/receiver device, and the problem of being very troublesome in the maintenance and inspection work thereof.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a train detection system, which can detect the existence of a train with the simple structure and is easily operable on the fail-safe basis, when a trouble occurs in transmitting or receiving a signal indicating the train existence.

Further, another object of the present invention is to provide a train detection system, which can easily detect the failure in a transmission path with the simple structure.

The above mentioned object can be attained by a train detection system comprising a transmitter for transmitting a train detective signal to a track circuit, a receiver for receiving the train detective signal from the track circuit, and a wayside controller, connected to the transmitter and the receiver through a data transmission path, for producing the train detective signal to the transmitter and receiving the train detective signal from the receiver to detect the existence of a train, wherein the transmitter comprises a unique code memory for storing first unique code data and adds the first unique code data to the train detective signal received from the wayside controller, which is then transmitted to the track circuit, the receiver comprises a unique code memory for storing second unique code data and adds the second unique code data to the train detective signal with the first unique code data received from the track circuit, which is then transmitted to the wayside controller, and the wayside controller comprises unique code checking means for checking whether or not the first unique code data and the second unique code data received from the receiver agree with contents of a predetermined data.

With the above mentioned construction, even if any failure occurs in a transmitter or a receiver and the receiver erroneously produces a detective signal indicating no existence of a train to a wayside controller, the controller judges the possibility of the train existence and can perform the safe control, because the detective signal does not include the unique code data or, if included, an included unique code data is not correct.

If any failure occurs in another portion in the transmission path, the failure can be detected in a similar way. Further, if the receiver erroneously receives the signal from an adjacent track circuit, which is transmitted to the wayside controller, the controller can judge that it is an error signal.

According to the above mentioned construction, if only a wayside controller for checking the unique codes is constructed with the very high reliability, a transmitter/receiver device to be provided for every track circuit can be made with the simple structure, which can reduce the cost of the total system (only a wayside controller is required for lot of track circuits).

Further, if the wayside controller is highly reliable, there occurs no serious problem, even if a transmitter/receiver device itself provided in every track circuit has the relatively low reliability. Therefore, it is possible to simplify the maintenance and inspection work of many transmitter/receiver devices arranged along a railway.

BRIEF DESCRIPTION OF THE DRAWINGS

<ul id="ul0001" list-style="none" compact="compact"><li>FIG. 1 schematically shows the construction of a train detection system according to an embodiment of the present invention;</li><li>FIG. 2 is a drawing showing an example of unique codes used in the embodiment of the present invention;</li><li>FIG. 3 is a flow chart showing a procedure of processing of a unique code adding in the embodiment of the present invention;</li><li>FIG. 4 is a flow chart showing a procedure of processing of a unique code checking in the embodiment of the present invention;</li><li>FIG. 5 is a flow chart showing a procedure of processing of a unique code adding in another embodiment of the present invention;</li><li>FIG. 6 schematically shows the construction of a train detection system according to another embodiment of the present invention; and</li><li>FIG. 7 is a flow chart showing a procedure of processing of a unique code checking in the another embodiment of the present invention.</li></ul>

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following, detailed description will be made of the present invention, referring to the accompanying drawings.

FIG. 1 shows the construction of a train detection system in accordance with an embodiment of the present invention. In order to detect the position of train 10 traveling on a track, the track is composed of n sections of track circuits (1, 2, ... n) sectioned by insulator members 70. Both ends of every track circuit are connected to transmitter/receiver devices (11a, 11b, 12a, ..., 1nb) for transmitting to and receiving from the track circuit, a signal for detecting the existence of a train in the track circuit. Each of the transmitter/receiver devices is also connected to wayside controller 100 through network 50.

In order to perform the processing for a train detection, the wayside controller 100 generates the train detection command information by train detection command generating portion 111 of train managing portion 110, which is transmitted to each of the transmitter/ receiver devices through the network 50.

The transmitter/receiver device receives the train detection command information from the wayside controller and transmits it to the track circuit. Since each of the transmitter/receiver devices is connected to another one through a track circuit (the transmitter/ receiver device 11a is connected to the transmitter/ receiver device 11b through the track circuit 1, for example), the train detection command information is transmitted to the another one by the transmission through the track circuit. Then, the another transmitter/receiver device transmits the information received from the track circuit as a received information to the wayside controller 100 through the network 50. The wayside controller 100 detects the existence of a train by presence or absence of the information received from the another transmitter/ receiver device.

In the case where a train exists in the track circuit 1, for example, rails are short-circuited by wheel shafts and accordingly a signal transmitted to the track circuit 1 by the transmitter/receiver device 11a cannot be received by the another transmitter/ receiver device 11b. As a result, the wayside controller 100 judges the existence of a train in the track circuit, based on absence of the received signal.

The transmitter/receiver devices (11a, 11b, 12a, ..., 1nb) have unique code memory portions (41a, 41b, 42a, ..., 4nb), in which unique code 1A, 1B, 2A, ..., nB is retained, respectively. Further, the transmitter/receiver devices (11a, 11b, 12a, ..., 1nb) have unique code adding portions (31a, 31b, 32a, ..., 3nb) for adding information of a unique code to the information string of a received signal, when the signal is transmitted to the track circuit and when the signal received from the corresponding track circuit is transmitted to the network 50.

As a method of transmitting arbitrary information through a track circuit, there is the method, by which an analog wave of the frequency of about 20 kHz is used and is modulated by frequency. Therefore, each of the transmitter/receiver devices can perform the processing operation of converting digital information to analog wave to transmit it to the track circuit and the processing operation of converting analog wave received from the track circuit to digital information. A method using DSP (Digital Signal Processor), for example, can be utilized for the processing as mentioned above.

Further, the wayside controller 100 comprises a unique code managing portion 130 for storing data relating to the correspondence between the track circuits and the transmitter/receiver devices as well as the unique codes of all the transmitter/receiver devices.

Using a unique code attached to a signal received from the network 50, the train detection command information obtained from the train detection command information generating portion 111 and a proper unique code obtained from the unique code managing portion 130, unique code checking portion 120 checks whether or not an error exists in the unique code attached to the signal received from the network 50.

Thereby, it is confirmed that the train detection command information transmitted to the network correctly corresponds to the received information. Then, the code agreement information is transferred from the unique code checking portion 120 to train managing portion 110. The train detection result judged by the train managing portion based on the code agreement information is stored in train detection result information memory portion 112 as a train detection result information, and the result of checking the code is stored in code agreement information memory 113 as a code agreement information.

At the same time, these results are displayed on display 150 and used for train control by signal control portion 140.

In such a construction, it is necessary to construct a wayside controller by using devices with the sufficient safety. To attain this, hardware may be constructed by a multisystem, for example. Further, a transmitter/receiver device can employ a simpler construction, compared with that of a wayside controller.

For example, it is possible to employ a device with such a simple construction that a ROM including a unique code memory portion therein as well as a microprocessor unit performing the processing for a unique code adding portion and the processing for the transmitting and receiving portion as described above are mounted on a board and accommodated in a cabinet. Therefore, cost for the total system can be reduced.

Furthermore, even if a failure occurs in a transmitter/receiver device itself and a signal indicating no existence of a train is erroneously produced to the wayside controller, the signal is added with no unique code or, if added, with an incorrect code. Therefore, a wayside controller can judge that there is the possibility of existence of a train in the track circuit and executes the safe control. Accordingly, the maintenance and inspection work of the large number of transmitter/receiver devices installed along a railway may be performed only when disagreement of the unique codes occurs in the wayside controller, which can simplify the maintenance and inspection work.

Fig. 2 shows examples of a unique code. The figure is a table, which correspondingly indicates the transmitter/receiver devices connected to corresponding track circuits, the unique codes retained in the transmitter/receiver devices and the specific bit data of the unique codes are correspondingly indicated. In this example, the unique codes are expressed in a form of 5 bit data and takes continuing value, but can be arbitrarily selected, as far as codes are different on the transmitting side and on the receiving side. However, it is more preferable that different unique codes are allotted to different track circuits as in the present embodiment, because an error can be certainly detected, even if a signal of the adjacent track circuit is erroneously received. Each of the transmitter/receiver devices retains only one unique code corresponding thereto, and the wayside controller stores all the unique codes in its unique code managing portion 130. For example, the wayside controller stores the table as shown in Fig. 2 in the unique code managing portion 130.

In the following, description will be made of an example of an information processing procedure among various devices in the train detection processing using these unique codes, in the case where it is detected whether or not a train exists in the track circuit 1.

At the outset, the wayside controller 100 transmits the train detection command information to the transmitter/receiver device 11a. The signal structure of the train detection command information is assumed as follows.<maths id="math0001" num="(1)"><math display="block"><mrow><mtext>Train existence detection command information</mtext><mspace linebreak="newline" /><mtext> = {011101}</mtext></mrow></math><img file="EP1535818A2_D0001.tif" /></maths>

Therefore, the following information is transmitted.<maths id="math0002" num=""><img file="EP1535818A2_D0002.tif" /></maths>

The transmitter/receiver device 11a adds the unique code to the train detection command information transmitted.

FIG. 3 shows an example of the procedure of adding the unique code.

The transmitter/receiver device 11a receives the train detection command information from the network 50, and transmits a signal to the track circuit 1 using the transmitter/receiver portion 21a. At that time, the unique code adding processing is performed by the unique code adding portion 31a in the transmitter/ receiver device 11a.

The unique code adding portion 31a adds the code information {00010} of the unique code 1A held in the unique code memory portion 41a to the train detection command information and sends the information after adding to the transmitter/receiver portion 21a for transmission. The adding is assumed to be a process for adding the information of the unique code to the information to be transmitted.

In this embodiment, although the code of adding information follows a series of the code of information added, the code of adding information may be placed before the series of the code of information added.

Thus, the following information is transmitted to the track circuit.<maths id="math0003" num=""><img file="EP1535818A2_D0003.tif" /></maths>

The transmitter/receiver device 11b receives a signal from the track circuit 1, and decodes it by using the transmitter/receiver portion 21b. The received information obtained as the result thereof is transmitted to the wayside controller 100 through the network 50. At this time, the received information is transmitted, after the code information {00011} of the unique code 1B held in the unique code memory portion 41b is added by using the unique code adding portion 31b. The procedure of adding is the same as shown in FIG. 3. To this end, the following information is transmitted.<maths id="math0004" num=""><img file="EP1535818A2_D0004.tif" /></maths>

As a result, the wayside controller 100 receives the information {011101}{00010}{00011} as the information corresponding with the transmitted information {011101}. The received information contains the unique codes of the transmitter/receiver device 11a and the transmitter/receiver device 11b which are devices on the information transmission path.

On the other hand, the wayside controller 100 recognizes, from data stored in the unique code managing portion 130, that the transmitter/receiver devices in the objective track circuit 1 are the transmitter/receiver device 11a and the transmitter/ receiver device 11b and the unique codes thereof.

The unique code checking portion 120 compares the received information with the information stored the unique code managing portion 130.

An example of the-processing procedure thereof is shown in FIG. 4.

First of all, the unique code checking portion 120 executes the processing of confirming whether or not there exists the information received from the network 50. If no information is received, the train detection result information to that effect is transmitted to the train managing portion 110.

If the information is received from the network 50, the unique code checking portion 120 receives the train detection command signal which has been transmitted from the train managing portion 110 to the track circuit through the network 50. Then, the unique code checking portion 120 receives a unique code of a transmitter/receiver device of a corresponding track circuit from the unique code managing portion 130. In this embodiment, the unique code 1A and the unique code 1B are received. The unique code checking portion 120 generates the information for checking (information would be received, if there is no failure in the transmission path).

Then, the unique code checking portion 120 checks whether or not a string of code agrees between the information actually received from the network 50 and the information for checking.

If the received information is normally transmitted, the following equation is satisfied.<maths id="math0005" num="(5)"><math display="block"><mrow><mtext>Transmitted information</mtext><mspace linebreak="newline" /><mtext> = {011101} {00010} {00011}</mtext></mrow></math><img file="EP1535818A2_D0005.tif" /></maths>

On the other hand, the information for checking is as follows.<maths id="math0006" num=""><img file="EP1535818A2_D0006.tif" /></maths>

Therefore, by the checking process in the unique code checking portion 120, it is judged that the received information and the information for checking agree with each other, and it can be confirmed that the transmitter/receiver device in the track circuit, in which a train is detected to exist, is one in the track circuit 1, which is to be detected.

In the foregoing, the checking is performed on both the train detection command signal and the identification code information. However, a failure of the transmitter/receiver device can be detected by checking of the later information only.

On the other hand, when a train exists in the track circuit 1, the signal transmitted by the transmitter/receiver device 11 to the track circuit 1 is short-circuited by wheels of the train, with the result that the signal is not received by the transmitter/receiver device and hence the signal does not return to the unique code checking portion 120.

As described above, the unique code checking portion 120 transmits information of indicating no received signal to the train managing portion 110. Receiving the information, the train managing portion 110 judges that a train exists in the track circuit 1, and the result of judgement is stored in the train detection result information memory portion 112 as train detection result information.

Next, description will be made on the case where a failure occurs in the transmitter/receiver devices 1a, 1b, the track circuit 1 and/or the network 50. As far as the detection of a train is concerned, the wayside controller 100 is required to judge that a train exists and to perform the processing so as to keep the safety of the train, even if the train does not actually exists.

Firstly, consideration will be given to the case where a failure occurs in either one or both of the transmitter/receiver devices 1a and 1b.

In the case where the unique code information has a failure, an information to be transmitted results in containing a code different from an original one. For example, when {00010} becomes {01010} because of a bit error in the transmitter/receiver device 1a, the unique code contained in the signal received by the wayside controller 100 does not agree with the information for checking.<maths id="math0007" num="(7)"><math display="block"><mrow><mtext>Received information = {011101} {01010} {00011}</mtext><mspace linebreak="newline" /><mtext> Information for checking = {011101} {00010} {00011}</mtext></mrow></math><img file="EP1535818A2_D0007.tif" /></maths>

As a result, the unique code checking portion 120 judges that the unique codes disagree. The checking portion 120 transmits the code agreement information including information on what unique code disagreed, to the train managing portion 110. With this, it is possible to detect the fact that a failure occurs in the transmission path.

Further, in the case where a failure occurs in the unique code adding portion 31b itself, the unique code is not contained in the transmitted information. As a result, the unique code contained in the signal received by the wayside controller 100 does not agree with the information for checking.<maths id="math0008" num="(8)"><math display="block"><mrow><mtext>Received information = {011101} { } {00011}</mtext><mspace linebreak="newline" /><mtext> Information for checking = {011101} {00010} {00011}</mtext></mrow></math><img file="EP1535818A2_D0008.tif" /></maths>

As a result, similarly to the above, it is possible to detect the fact that a failure occurs in the transmission path.

In the case where no signal is transmitted to the track circuit due to a failure, no signal flows through the track circuit 1. Since no signal is returned to the wayside controller, it is judged that no signal exists and hence a train is in the track circuit. Accordingly, the safety can be ensured.

Next, consideration will be given to the case where a failure occurs in the track circuit 1 and/or the network 50. When information cannot be transmitted by such a failure in the track circuit or the network circuit, a situation becomes similar to the situation that no signal is transmitted due to a failure of a transmitter/receiver device. Therefore, the wayside controller judges that no signal exists and hence a train is in the track circuit. Accordingly, the safety can be ensured in this case, too.

Further, when a transmitted information is changed by occurrence of a bit error during transmission, a situation becomes similar to the situation that a failure occurs in the unique code of a transmitter/ receiver device or in the unique code adding portion. Accordingly, the occurrence of a failure in the transmission path can be-detected by the checking process of the wayside controller.

When a failure is detected to occur in the transmission path and nevertheless the train detection processing is continued, there is the possibility that the safety of a train can not become ensured. When, therefore, the occurrence of a failure is detected, the processing as follows is done, whereby the safety of a train must be secured.

For example, first of all, the occurrence of a failure is displayed in the displaying portion 150 to inform an operation controller thereof. Further, by informing the signal control portion 140 of the occurrence of a failure, various traffic signals are controlled under the assumption that a train exists in a corresponding track circuit. Furthermore, simply, a traffic signal for stop can be given to a train.

As described above, the train detection system according to the present embodiment can ensure the safety of the train, even in the case where a failure occurs in devices on a transmission path.

In the following, another embodiment of the present invention will be described.

With respect to this embodiment, description will be done of the case where, as another example of the processing method in the unique code adding portion, a mask processing is carried out on an information series of a received signal, based on an information series of a unique code.

In this embodiment, it is assumed that the EOR (Exclusive OR) processing is utilized for the mask processing. It is clear that even if a logical operation processing other than the Exclusive OR is utilized, it is possible to confirm whether or not a correct information is returned to a wayside controller, as far as the same effect as the mask processing in the unique code checking portion can be attained.

FIG. 6 schematically shows the construction of the train detection system according to the present embodiment, and FIG. 5 shows the flow of the unique information adding processing in the present embodiment. In FIG. 6, the same reference character as in FIG. 1 indicates the same as in FIG. 1.

Unique code adding portion 160 as well as unique code adding portions 31a, 31b, 32a, ..., 3nb send out the result of the mask processing, which is carried out with respect to a received information by using the EOR processing between the received information and the unique code.

Further, in this embodiment, the above mentioned mask processing is performed in the unique code checking portion 120, as described later. If a received information is large, compared with the unique code, the mask processing is performed with respect to each of information series divided into the size of the unique code. Further, if the size of a received information or a part of the aforesaid information divided is smaller than that of the unique code, a provisional information is temporarily added to the information series at the rear thereof to thereby adjust the length, and cut off when reconstructed of the information.

The EOR processing has such a characteristic that an original code can be obtained, only when processing using the same code is repeated twice with respect to an objective code. Then, the following is assumed in the present embodiment: i.e., the mask processing is performed in a unique code adding portion in a transmitter/receiver device on the transmitting side.

In the present embodiment, however, the processing corresponding to such mask processing is performed in the unique code adding portion 160 of the wayside controller 100, in advance, and thereafter the thus processed signal is transmitted. Further, the unique code checking portion 120 of the wayside controller 100 executes the processing corresponding to the mask processing carried out in the unique code adding portion in a transmitter/receiver device on the receiving side. Referring to FIG. 5, the unique code adding processing in this embodiment will be-described below. FIG. 5 is the flow chart showing the unique code adding processing of the unique code adding portion 160. Description will be made on the case where processing of detecting a train in the track circuit 1 is performed in the construction as shown in FIG. 6.

In the wayside controller 100, first of all, the train managing portion 110 generates a train detection command information by the train detection command information generating portion 111. The content of the train detection command information is assumed as follows.<maths id="math0009" num=""><math display="block"><mrow><mtext>Train detection command information = {011101}</mtext></mrow></math><img file="EP1535818A2_D0009.tif" /></maths>

The train detection command information is transferred to the unique code adding portion 160, which portion performs the mask processing with respect to the train detection command information. This mask processing uses the unique code (unique code 1A) retained in the transmitter/receiver device 11a which receives the train detection command information.

The unique code adding portion 160 firstly receives the unique code (unique code 1A) of the transmitter/receiver device 11a as a destination device from the unique code managing portion 130.<maths id="math0010" num="(10)"><math display="block"><mrow><mtext>Identification code 1A = {00010}</mtext></mrow></math><img file="EP1535818A2_D0010.tif" /></maths>

It can be understood that the information series of the train detection command information is longer than the information series of the unique code 1A. Then, the unique code adding portion 160 divides the objective train detection command information into a plurality of information series with a unit of length of the unique code 1A and performs the EOR processing with respect to each of the plurality of information series. The thus processed information series are constructed in one information series, again. As a result, the wayside controller 100 transmits the following information to the network 50, which has been subject to the mask processing in the unique code adding portion 160.<maths id="math0011" num=""><img file="EP1535818A2_D0011.tif" /></maths><maths id="math0012" num=""><img file="EP1535818A2_D0012.tif" /></maths>

Next, the transmitter/receiver device 11a receives the transmitted information from the network 50 and performs the mask processing by the unique code adding portion 31a. At this time, the unique code 1A retained in the unique code memory portion 41a of the transmitter/receiver device 11a is utilized. The procedure of the mask processing is the same as that of the processing shown in FIG. 5. As a result, the information transmitted to the track circuit 1 by the transmitter/receiver device 11a is as follows.<maths id="math0013" num=""><img file="EP1535818A2_D0013.tif" /></maths>

The processing performed by the transmitter/receiver device 11b, which receives the transmitted information from the track circuit 1, is the same as the mask processing of the transmitter/receiver device 11a. However, the transmitter/receiver device 11b performs the processing using the information {00011} of the unique code 1B retained in the unique code memory portion 41b and sent the result thereof to the network 50.<maths id="math0014" num=""><img file="EP1535818A2_D0014.tif" /></maths>

As a result, the wayside controller 100 receives the information {011011}, instead of the train detection command information {011101}. The content of the received information is confirmed in the unique code checking portion 120. This procedure is shown in FIG. 7.

Since the transmitted information received by the wayside controller 100 is subject to the mask processing by the unique code 1B of the transmitter/receiver device 11b, it is subject to the mask processing, again, and needs to be restored to the original code, before the confirmation in the unique code checking portion 120. The procedure of this mask processing is the same as that of the processing shown in FIG. 5.

That is, in the unique code checking portion 120, it is confirmed at first whether or not the transmitted information is received from the network 50. If received, a restored information is obtained by the mask processing with respect to the transmitted information received, which processing uses the unique code 1B {00011} corresponding to the transmitter/ receiver device 11b. The unique code 1B is obtained from the unique code managing portion 130.<maths id="math0015" num=""><img file="EP1535818A2_D0015.tif" /></maths>

Next, the unique code checking portion 120 receives the original train detection command information from the train managing portion 110.<maths id="math0016" num="(15)"><math display="block"><mrow><mtext>Train existence detection command information</mtext><mspace linebreak="newline" /><mtext> = {011101}</mtext></mrow></math><img file="EP1535818A2_D0016.tif" /></maths>

Then, the unique code checking portion 120 performs the processing to check whether or not the recovered information agrees with the train detection command information obtained from the train managing portion 110. If no failure exists in the transmission path, the recovered information agrees with the train detection command information.

Therefore, it can be confirmed that the train detection command information is the information returned through the transmitter/receiver devices 11a and 11b. The result of code agreement is sent from the unique code checking portion 120 to the train managing portion 110, which recognizes that no train exists in the track circuit 1 from the fact that the codes agree with each other.

On the other hand, when a train exists within the track circuit 1, any information to be transmitted to the wayside controller 100 does not exist, since the transmitter/receiver device 11b receives no signal. As the result, the train managing portion 110 judges that a train exists within the track circuit 1. The procedure of this judgement is as described previously. The result of judgement is stored in the train detection result information memory portion 112 as the train detection result information.

As far as troubles in the transmitter/receiver devices 11a and 11b are concerned, in the case where they transmit or receive no signal, it is possible to ensure the safety by judging that a train exists, since no signal to the wayside controller 100 exists, as described previously. Further, as far as troubles in the track circuit 1 and the network 50 are concerned, in a case where the track circuit 1 or the network 50 is disconnected, the same as described above can be applied.

On the other hand, in a case where a failure occurs in the unique code adding portion 31a or 31b of the transmitter/receiver device 11a or 11b, or in a case where an error occurs in the unique code retained therein, the wayside controller 100 performs the mask processing with respect to a transmitted information, which is different from an information to be received in the normal condition, and generates a restored information.

Therefore, in a case where the unique code 1B {00011} held by the transmitter/receiver device 11b becomes a different information series of the unique code 1B' {01011} due to an error, the following information will be transmitted to the wayside controller 100.<maths id="math0017" num=""><img file="EP1535818A2_D0017.tif" /></maths>

Accordingly a restored information obtained by the unique code checking portion 120 in the wayside controller 100 becomes as follows.<maths id="math0018" num=""><img file="EP1535818A2_D0018.tif" /></maths>

This result does not agree with the train detection command information {011101} obtained from the train managing portion 110. Therefore, the unique code checking portion 120 sends the disagreement of codes to the train managing portion 110 as a code agreement/disagreement information, and the train managing portion 110 stores the transmitted information in the code agreement information memory portion 113.

As described above, the wayside controller 100 can detect that a unique code adding process in a transmitter/receiver device on a transmission path is not operating correctly. When the disagreement of the codes is detected, the train managing portion 110, as described before, performs the processing necessary for a safe train control against the signal control portion 140 and the display portion 150 in accordance with the result of the train existence judgement as well as the failure detection result in devices within the transmission path.

According to the embodiment described above, even if a failure occurs in a transmitter/receiver device, which erroneously outputs a detection signal indicating no train existence to the wayside controller 100, the output signal is not accompanied by the unique code signal (or is not subject to the mask processing). Even if accompanied, it is not a correct unique code data (or data obtained by an erroneous mask processing). Therefore, the wayside controller 100 judges that there is the possibility of the existence of a train within the track circuit, whereby the safe control can be performed.

Further, even if a failure occurs in the information transmission to the network 50 or the track circuit, the occurrence of the failure can be detected in the same manner as above. Furthermore, since an individual code is allotted for every track circuit, the transmission of an erroneous data can be detected, even if a transmitter/receiver device erroneously receives a signal from an adjacent track circuit and transmits it to a wayside controller.

According to the construction of the above mentioned embodiment, if the wayside controller 100, which performs checking of unique codes, is constructed as a highly reliable system (as a multi-system computer, for example), the construction of a transmitter/ receiver device provided in every track circuit may be simplified, and accordingly the cost of the total system can be reduced. Further, there is no problem in the safe traffic control of trains, even if the reliability of a transmitter/receiver device itself provided in every track circuit is relatively low, if only a wayside controller has the reliability sufficiently high.

Therefore, it is possible to simplify the maintenance and inspection work of lot of transmitter/receiver devices arranged along a railway.

As described above, according to the present invention, it is possible to realize a train detection system, which is capable of certainly detecting a failure in track circuits with the simple construction of the system.