JP2010163118A - Train position detecting system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a multipath error in effectively detecting a train position with a simple constitution, by making the most use of a condition such as a railroad field. <P>SOLUTION: One or more reference stations 11 arranged on the ground for receiving a satellite signal from a satellite 24, selects the predetermined number of satellite combinations from the received satellite signals, and calculates the position of the reference station 11 from the selected satellite signal, and generates and transmits high precedence satellite combination information being a combination list of the satellite of a small error to a train 13. A pick-up device of the train 13 receives the satellite signal from the satellite 14, and receives the high precedence satellite combination information generated by the reference station 11, and selects a satellite combination of becoming small in a position error from the received satellite signals, and calculates a position of the train based on the satellite signal received by using the selected satellite signal. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a train position detection system using a positioning satellite system.

  Positioning satellite systems represented by GPS (Global Positioning System) that uses radio waves from artificial satellites are widely used in fields such as aviation, ships, and automobiles. In the railway field, the introduction of positioning satellite systems is progressing little by little. Recently, operation of a driver assistance system using GPS was started in 2008. In safety control in the railway field, high stability and position accuracy are required, and therefore some measures to improve performance must be taken when adopting GPS.

  As for the railway field, there is a train travel information detection apparatus and a train travel information detection method capable of calculating a position using only two satellite signals by using three-dimensional track data (for example, Patent Documents). 1). In addition, as an object for all moving objects, an infrared camera is installed on the upper part of the moving object, and the presence / absence of obstacles is determined in real time using an image of the upward direction, and satellites in the direction of the obstacles are excluded. There is a thing (for example, refer nonpatent literature 1).

JP 2004-168216 A

Author Meguro Junichi et al., High-precision GPS positioning using an infrared all-around camera, GPS / GNSS Symposium 2006

  However, a positioning satellite system such as GPS is effective as one of means for detecting the position of a train, but since there are generally many buildings around the track, there is a high possibility that a lot of reflection and diffraction will occur. If such a reflected wave or diffracted wave is received, an error occurs in the calculation of the distance between the receiver and the satellite, and as a result, an error also occurs in the position information. Such an error is generally called a multipath error. Multipath errors occur particularly prominently in urban areas, and if no countermeasure is taken, the position error amount may reach 100 m or more.

  Various types of correlator methods such as narrow correlator and strobe correlator and methods using signal intensity have been announced as methods for reducing multipath errors, but no definitive one has been developed. Further, if an effective multipath error reduction method is to be realized, there is a tendency that expensive equipment for complicated processing is required.

  An object of the present invention is to provide a train position detection system that can effectively reduce the multipath error in train position detection with a simple configuration, taking advantage of the condition of the railway field.

  A train position detection system according to the present invention is a train position configured by one or more reference stations installed on the ground for receiving satellite signals from satellites and on-board devices respectively mounted on one or more trains. In the detection system, the reference station includes a satellite signal receiving unit that receives a satellite signal from the satellite, a satellite combination selecting unit that selects a predetermined number of satellite combinations from the satellite signals received by the satellite signal receiving unit, A position information calculation unit that calculates the position of the reference station from the satellite signal selected by the satellite combination selection unit, and a small error between the position calculated by the position information calculation unit and a predetermined true position of the reference station A high-priority satellite combination information generating unit that determines a combination of satellites and generates high-priority satellite combination information that is a list of satellite combinations with a small error; and the high-priority satellite combination An on-vehicle transmission device for transmitting high priority satellite combination information generated by the information generation unit to the train, and the on-vehicle device of the train receives a satellite signal from the satellite. An on-ground transmission device for receiving the high-priority satellite combination information generated by the reference station, and the satellite signal receiving unit using the high-priority satellite combination information received by the ground-vehicle transmission device. Based on the satellite signal received by the satellite signal receiver using the satellite signal selected by the satellite combination selector, a satellite combination selector that selects a satellite combination with a small positional error from the received satellite signals. And a position calculation unit for calculating the position of the train.

  According to the present invention, it is possible to effectively reduce the multipath error in train position detection with a simple configuration, taking advantage of the condition of the railway field.

The block diagram of the ground reference station in Example 1 of embodiment of this invention. The block diagram of the on-train apparatus of the train in Example 1 of embodiment of this invention. The schematic diagram which showed the arrangement | positioning of the reference station and train in Example 1 of embodiment of this invention from the viewpoint from the sky. The schematic diagram which showed the arrangement | positioning of the reference station and train in Example 1 of embodiment of this invention from the horizontal direction. The schematic diagram of the other example which showed the arrangement | positioning of the reference station and train in Example 1 of embodiment of this invention from the viewpoint from the sky. The block diagram of the on-train apparatus of the train in Example 2 of embodiment of this invention. The block diagram of the reference | standard station in Example 3 of embodiment of this invention. The block diagram of the ground reference station in Example 4 of embodiment of this invention. The block diagram of the on-train apparatus of the train in Example 4 of embodiment of this invention. Explanatory drawing of the geometric distance and pseudo distance used in Example 4 of an embodiment of the invention. The block diagram of the on-train apparatus of the train in Example 5 of embodiment of this invention. The block diagram of the reference | standard station in Example 6 of embodiment of this invention.

  Hereinafter, an embodiment of a train position detection system according to the present invention will be described with reference to the drawings. In the following description, the name GPS is used as a general term for positioning satellite systems. This is because the name GPS is generally used as a generic name for similar systems. The present invention is not limited to the US positioning satellite system, but can be applied to other positioning satellite systems such as GLONASS and Galileo.

  Here, the principle of GPS positioning will be described. In order to know the position of the self (GPS antenna) using the satellite, the position of the satellite and the distance between the self (GPS antenna) and the satellite are required. The position (xk, yk, zk) of a certain satellite Sk can accurately grasp when and where the satellite is located by obtaining satellite orbit information (ephemeris) transmitted from the satellite.

  On the other hand, the distance between the satellite (GPS antenna) and the satellite can be calculated by multiplying the radio wave propagation time tk from the satellite by the light velocity c. The radio wave propagation time is calculated from the difference between the time of the satellite clock at the moment when the radio wave is transmitted and the time of the receiver clock at the moment when the radio wave is received. The distance calculated in this way is called a pseudo distance. In general, since the accuracy of the satellite clock is very high, the clock error can be ignored, but the clock error of the receiver clock cannot be ignored, and the pseudorange includes an error corresponding to the clock error Δt of the receiver clock. From the above, it is possible to formulate the following equations for each satellite, where the position of itself (GPS antenna) is (x, y, z).

{(xk−x) ² + (yk−y) ² + (zk−z) ² } ^1/2 = c × (tk + Δt) (1)
Since there are four unknowns (x, y, z, Δt), if the above equation is established for four satellites, the solution of the simultaneous equations, that is, the position of itself (GPS antenna) can be obtained.

  In general, the position error due to the error of the satellite orbit information is about 2 m at the maximum and is not so large. The main cause of the position error is an error in the radio wave propagation time. There are several factors in the radio propagation time error, such as ionospheric delay and tropospheric delay. Among them, multipath has a large error variation and is difficult to deal with. In the present invention, a satellite that is not affected by reflection or is small is extracted by a ground reference station, and the position is calculated on the vehicle by using the satellite with priority. By doing so, a high-quality satellite can be selected and multipath errors can be reduced.

  In the train position detection system of the present invention, a reference station is installed on the railway line. The reference station determines a satellite that is less affected by multipath errors and transmits it to a nearby train. In general, there are many straight lines on the track, so it seems that the way the satellites look on the reference station and the train does not change significantly. Therefore, a satellite with a small multipath error at the reference station is likely to have a small multipath error on the vehicle as well, and if the GPS position is calculated on the vehicle by using the satellite preferentially, the accuracy will be improved. Train position information can be obtained.

  The following describes a method for determining whether a satellite is good or bad at the reference station. The reference station stores its own true position (strictly speaking, position information with an error within a few centimeters). This true position is compared with the position information calculated by the reference station GPS. Thereby, it is possible to know how much position error is caused by the combination of the satellites used at that time. If the position error is calculated in the same way for all combinations that can be selected from all the satellites that can be captured at that time, which satellite combination is good and which satellite combination is bad. Can be determined. Even without calculating the position, a satellite with a small pseudorange error can be determined as a high-quality satellite based on the geometric distance between the true position of the reference station and the satellite.

  Example 1 will be described below. In the first embodiment, the reference station determines whether the combination of the satellites is good or bad, and transmits the information to the vehicle.

  1 is a configuration diagram of a ground reference station in the first embodiment, FIG. 2 is a configuration diagram of an on-board apparatus in the first embodiment, and FIG. 3 is a schematic diagram illustrating the arrangement of the reference station and the train in the first embodiment from a viewpoint from the sky. FIG. 4 is a schematic diagram showing the arrangement of the reference station and the train in the first embodiment as a starting point from the horizontal direction.

  As shown in FIG. 3, a plurality of reference stations 11 are installed along the line 12. FIG. 3 shows a case where trains 13 a and 13 b are traveling on the track 12. An area indicated by a dotted line is an area covered by each reference station 11. The installation interval of the reference station 11 is about 5 km in a straight section. Since the appearance of the satellite changes in the curve section, the installation interval of the reference station 11 is shortened. As shown in FIG. 4, the reference station 11 receives satellite signals S1 to Sn from a plurality of satellites 14a to 14n.

As shown in FIG. 1, in the reference station 11, the satellite signal receiver 15 receives satellite signals S1 to Sn at the same time from a plurality of satellites 14a to 14n. The satellite signals S <b> 1 to Sn received at the same time by the satellite signal receiving unit 15 are stored in the satellite signal temporary storage unit 16. Then, the satellite combination selection unit 17 selects four satellites in a brute order sequentially from these satellites 14a to 14n. The position information calculation unit 18 calculates position information from the four equations shown in the equation (1) for all the combinations of the satellites combined by the satellite combination selection unit 17. The position information of each satellite combination obtained in this way is output to the high priority satellite combination information generation unit 19. The high-priority satellite combination information generation unit 19 compares the true position of the reference station 11 stored in advance in the true position information storage unit 20 (for example, position information having an error of about several centimeters measured using RTK-GPS). The comparison results are shown in Table 1.

Then, the high priority satellite combination information generation unit 19 extracts, for example, an error amount within 5 m as the high priority satellite combination information and stores it in the high priority satellite combination information storage unit 21. Table 2 shows an example of high priority satellite combination information.

The high-priority satellite combination information is, for example, satellite combination information in the upper part of the satellite combination rank table as shown in Table 1. The method of assigning superiority or inferiority of the satellite combination is not particularly limited. Here, the position error is expressed in three dimensions (x, y, z), and this magnitude, that is, the square root of (x ² , y ² , z ² ). The superiority or inferiority of the satellite combination is determined. In the example of Table 2, the best combination of satellites is a combination of satellite numbers 2, 3, 4, and 6. As high-priority satellite combination information for transmission on the vehicle, as described above, for example, information having an error amount of 5 m or less is extracted.

  The allowable error amount may be set to a very large value, and all the satellite combination information may be used as the high priority satellite combination information. The information thus obtained is stored in the high priority satellite combination information storage unit 21. The high priority satellite combination information storage unit 21 may store past information or may store only the latest information. Then, the latest stored high-priority satellite combination information T is transmitted to the train 13 at a certain cycle (for example, 10 seconds) using the on-vehicle transmission device 22.

  As shown in FIG. 2, the on-board device 23 of the train 13 receives the high-priority satellite combination information T from the reference station 11 by the ground on-vehicle transmission device 24. The high priority satellite combination information T received from the reference station 11 and received by the on-vehicle transmission device 24 is stored in the high priority satellite combination information storage unit 25. Then, the satellite combination selection unit 26 among the high-priority satellite combination information T stored in the high-priority satellite combination information storage unit 25 among the satellite signals S1 to Sn received by the satellite signal reception unit 27. The combination of the satellites having the highest ranking is selected as much as possible, and the position calculation unit 28 calculates the position using the combination of the satellites selected by the satellite combination selection unit 26.

  At this time, correction by a general DGPS function or the like may be performed. If the satellite combination as in the high priority satellite combination information transmitted from the reference station 11 cannot be selected, it is determined that the accuracy of the position calculated by the GPS is low, and the position calculation by the GPS is not performed. You may make it perform position calculation using other measuring instruments, such as a speed generator and a gyro.

  Here, regarding the transmission method from the reference station 11 to the on-board device 23, transmission is performed directly from the reference station 11 to the on-board device 23 of the train 13 using radio, but other communication means may be used. For example, as shown in FIG. 5, it may be transmitted indirectly via a ground central device 29 or the like, or may be communicated by wire. Moreover, the method of selecting and transmitting the train 13 on the reference station 11 side, or the method of selecting and transmitting the reference station 11 on the train 13 side may be used.

  According to the first embodiment, the reference station 11 determines whether the combination of the satellites 14a to 14n is good or bad, transmits the information to the train 13, and the onboard device 23 of the train 13 is based on the high-priority satellite combination. Since the position of the train 13 is calculated by selecting a satellite, it becomes possible to select a satellite with a smaller multipath error, and the position accuracy is improved. Further, the on-board device does not need to perform complicated processing and can be realized with a simple configuration.

  Next, Example 2 will be described. The second embodiment is different from the first embodiment in that the position is corrected by the on-board device 23 of the train 13 by the error amount of the position of the reference station 11 calculated by the reference station 11. FIG. 6 is a configuration diagram of the on-board device 23 of the train of the second embodiment. The on-board device 23 of the train is provided with a correction position calculation unit 30 that calculates the train position with respect to the calculation result calculated by the position calculation unit 28. The correction position calculation unit 30 corrects the position error transmitted from the reference station 11 by the magnitude and direction.

That is, the high priority satellite combination information generation unit 19 of the reference station 11 includes not only the satellite combination with a small position error shown in Table 2 but also the satellite combination of each satellite combination as shown in Table 3 in the high priority satellite combination information T. The information including the magnitude of the position error and the direction of the error is transmitted to the train 13 via the on-vehicle transmission device 22.

  Then, the on-board device 23 of the train corrects the calculation result calculated by the position calculation unit 28 by the amount and the direction of the position error obtained by the reference station 11 to calculate the train position.

  As described above, the high priority satellite combination information T transmitted from the reference station 11 includes information on the magnitude and direction of the position error as shown in Table 3. Specifically, as in the first embodiment, when the ranking table of Table 1 is obtained at the reference station 11 and the allowable error amount is set to 5 m, in the second embodiment, in Table 2, the high priority satellite combination information T is used as the train priority information. Transmit to the ground device 22.

  The on-board device 23 of the train selects a satellite combination having a higher rank by the satellite combination selection unit 26 based on the high-priority satellite combination information T received from the on-vehicle transmission device 24, and sends it to the position calculation unit 28. To calculate the train position. Further, with respect to the calculated position, the corrected position calculation unit 30 calculates a position where position correction has been performed for the magnitude and direction of the error.

  According to the second embodiment, as in the first embodiment, it is possible to select a satellite with a small multipath error. Furthermore, since error sources having a relatively large influence such as an ionospheric error and a tropospheric error, including a multipath error, can be removed to some extent, higher position accuracy can be expected as compared with the first embodiment. In addition, compared with general DGPS, since the multipath error can be reduced in the second embodiment, the position accuracy is improved.

  Next, Example 3 will be described. In the third embodiment, the DGPS position is calculated by the reference station 11 with respect to the first or second embodiment, and errors other than multipath are excluded, and the quality of the satellite combination is determined. FIG. 7 is a configuration diagram of the reference station 11 according to the third embodiment. The reference station 11 in the third embodiment is to use a DGPS (Differential GPS) function with respect to the reference station 11 in the first embodiment shown in FIG. Specifically, pseudo-range correction information D (information such as ionospheric delay error and tropospheric delay error) is acquired by a system such as a DGPS reference station or a SBAS (Satellite Based Augmentation System) installed in a place with a good view. Then, the latest one is stored in the pseudo distance correction information storage unit 31.

  Then, the position information calculation unit 18 calculates the position after performing pseudo-range correction, and the high-priority satellite combination information generation unit 19 compares the position with the true position. The same high priority satellite combination information is generated and transmitted to the onboard device 23 of the train 13 using the ground onboard transmission device 22.

  The on-board device 23 takes the configuration shown in FIG. 2 or 6 and performs the same processing as in the first or second embodiment to calculate the position of the train 13. At this time, the position may be calculated by performing correction by a general DGPS function.

  According to the third embodiment, in the first and second embodiments, when the multipath error is not so large, the multipath error is buried in other errors, and there is a possibility that the presence / absence of the multipath cannot be correctly determined. However, since the third embodiment eliminates other errors first, it can cope with a small multipath error.

  Next, Example 4 will be described. The fourth embodiment is different from the first embodiment in that the quality of the satellite is determined in units of satellites instead of the satellite combination. Here, the quality of the satellite is determined based on the pseudorange error. Also in the fourth embodiment, the reference station is arranged along the line as in the first embodiment.

  8 is a configuration diagram of the ground reference station in the fourth embodiment, FIG. 9 is a configuration diagram of the on-board device in the fourth embodiment, and FIG. 10 is an explanatory diagram of the geometric distance and the pseudo distance used in the fourth embodiment. The fourth embodiment is different from the first embodiment in that it is determined whether the satellite is good or bad instead of the combination unit of the satellites. The determination method is a geometrical relationship between the satellite position and the true position for each satellite. Based on the distance, the determination is made based on the magnitude of the pseudo-range error.

As shown in FIG. 8, the reference station 11 stores the satellite signals S <b> 1 to Sn received at the same time by the satellite signal receiving unit 15 in the satellite signal temporary storage unit 16. For each satellite, the pseudo distance calculation unit 32 calculates the pseudo distance. Further, the geometric distance calculation unit 33 calculates the geometric distance. As shown in FIG. 10, the pseudo distance is calculated by multiplying the radio wave propagation time tk from the satellite and the light velocity c. The geometric distance is calculated from the position of the reference station and the position of the satellite. The high priority satellite information generation unit 34 compares the pseudo distance calculated by the pseudo distance calculation unit 32 with the geometric distance calculated by the geometric distance calculation unit 33. Table 4 shows the comparison results. Table 4 shows the satellite ranking table.

Then, the high priority satellite information generation unit 34 generates high priority satellite information. For example, a distance error amount of 5 m or less is extracted as high priority satellite information and stored in the high priority satellite information storage unit 35. Table 5 shows an example of high priority satellite information.

  The high-priority satellite information is, for example, satellite information in the upper part of the satellite ranking table as shown in Table 4. In the example of Table 5, it can be said that the best satellite is the third satellite. As high-priority satellite information, as described above, for example, information having a distance error amount (difference between pseudo distance and geometric distance) within 5 m is extracted. Note that the allowable error amount may be set to a very large value, and the entire rank table may be used as the high priority satellite information. The information thus obtained is stored in the high priority satellite information storage unit 35. The high priority satellite information storage unit 35 may store past information or may store only the latest information. Then, the latest high-priority satellite information U stored is transmitted to the train 13 at a certain cycle (for example, 10 seconds) using the on-vehicle transmission device 22.

  As shown in FIG. 9, the on-vehicle device 23 of the train 13 receives the high-priority satellite information U from the reference station 11 by the ground on-vehicle transmission device 24. The high priority satellite information U received from the reference station 11 and received by the on-vehicle transmission device 24 is stored in the high priority satellite information storage unit 36. The satellite selection unit 37 has a higher rank among the high priority satellite information U stored in the high priority satellite information storage unit 36 among the satellite signals S1 to Sn received by the satellite signal reception unit 27. The satellite is preferentially selected, and the position calculation unit 28 calculates the position using the satellite selected by the satellite selection unit 37.

  At this time, correction by a general DGPS function or the like may be performed. If the number of satellites that can be selected from the high-priority satellite information transmitted from the reference station 11 is less than four, it is considered that the accuracy of the position calculated by the GPS is low, such as a speed generator or a gyro. The position may be calculated using the measuring instrument.

  Here, regarding the transmission method from the reference station 11 to the on-board device 23, in the fourth embodiment, transmission from the reference station 11 to the train 13 is performed directly using radio waves, but other communication means may be used. For example, as shown in FIG. 5, it may be transmitted indirectly via a ground central device 29 or the like, or may be communicated by wire. Moreover, the method of selecting and transmitting the train 13 on the reference station 11 side, or the method of selecting and transmitting the reference station on the train side may be used.

  According to the fourth embodiment, the processing amount at the reference station 11 is reduced as compared with the first embodiment, and the transmission amount from the reference station 11 to the train 13 is also reduced. Regarding the position accuracy, basically, the same effect as that of the first embodiment can be expected. Note that simply selecting a satellite with a small pseudorange may cause a bias in the direction of the satellite, which may slightly reduce the accuracy.

  Next, Example 5 will be described. In the fifth embodiment, the position of the train 13 is calculated by correcting the pseudo distance by the on-board device 23 for the pseudo distance error in the reference station 11 with respect to the fourth embodiment. FIG. 11 is a configuration diagram of the on-board device 23 of the train according to the fifth embodiment. The difference from the fourth embodiment is that the high priority satellite information generation unit 35 of the reference station 11 includes not only a list of satellites in which the difference between the pseudorange and the geometric distance is small in the high priority satellite information U, but also the satellite information. The pseudo-range error including the magnitude of the pseudo-range error is transmitted to the train 13 via the on-vehicle transmission device 22, and the on-board device 23 of the train 13 performs the pseudo correction for correcting the magnitude of the pseudo-range error transmitted from the reference station 11. The position calculation unit 28 includes a distance correction unit 38 and calculates the train position in consideration of the pseudo distance error corrected by the pseudo distance correction unit 38.

That is, the high priority satellite information U includes information regarding the magnitude of the pseudorange error. Specifically, as in the fourth embodiment, the base station 11 obtains the satellite ranking table of Table 4 and obtains high priority satellite information including the magnitude of the pseudorange error when the allowable error amount is 5 m. Table 6 shows an example of high priority satellite information including the magnitude of the pseudorange error.

  The on-board device 23 of the train 13 preferentially selects a satellite having a higher rank by the satellite selection unit 37 based on the high-priority satellite information U received from the on-vehicle transmission device 24, and further corrects the pseudo distance. The unit 38 corrects the pseudorange based on the error amount observed at the reference station 11. Then, using the pseudo distance, the position calculation unit 28 calculates the position of the train 13.

  According to the fifth embodiment, as in the second embodiment, it is possible to select a satellite with a small multipath error. In addition, error sources that have a relatively large influence, such as multipath errors, ionospheric errors, and tropospheric errors, can be removed to some extent. In general DGPS, the multipath error cannot be reduced, but in this embodiment, the multipath error can also be reduced, so that the position accuracy is improved. Compared with the second embodiment, the fifth embodiment has a smaller processing amount at the reference station and a smaller transmission amount.

  Next, Example 6 will be described. In the sixth embodiment, compared to the fourth or fifth embodiment, the DGPS correction is performed in the reference station 11 and the pseudorange error is calculated to determine whether the satellite is good or bad.

  FIG. 12 is a configuration diagram of the reference station 11 according to the sixth embodiment. The difference from the fourth embodiment and the fifth embodiment is that the reference station 11 uses a DGPS (Differential GPS) function. Specifically, pseudo-range correction information D (information such as ionospheric delay error and tropospheric delay error) is acquired by a system such as a DGPS reference station or a SBAS (Satellite Based Augmentation System) installed in a place with a good view. The latest information is stored in the pseudo distance correction information storage unit 31.

  Then, using the correction amount, the pseudo distance calculation unit 32 calculates the pseudo distance of each satellite. Further, the geometric distance calculation unit 33 obtains the geometric distance between the reference station 11 and each of the satellites 14a to 14n. Then, the high-priority satellite information generation unit 34 compares the pseudo distance and the geometric distance to generate high-priority satellite information U similar to that in the fourth or fifth embodiment, and the on-vehicle transmission device 22 Is transmitted to the train 13 using.

  The on-board device 23 of the train 13 has the configuration shown in FIG. 9 or FIG. 11, and performs the same processing as in the fourth or fifth embodiment to calculate the position of the train. At this time, correction by a general DGPS function may be performed on the vehicle.

  According to the sixth embodiment, when the multipath error is small, the multipath error may be buried in another error and the presence / absence of the multipath may not be correctly determined. Since this is eliminated, small multipath errors can be handled. Compared to the third embodiment, the amount of processing at the reference station 11 and the amount of transmission from the reference station 11 to the train 12 can be small.

Next, Example 7 will be described. The seventh embodiment is different from the first to sixth embodiments in that a combination of satellites or satellites that change rapidly in a short time is excluded. The seventh embodiment will be described as an extension of the fourth to sixth embodiments. In the seventh embodiment, the high-priority satellite information generation unit 34 of the reference station 11 accumulates, for example, satellite information having a 1-second cycle for the past 3 minutes, and excludes satellites whose fluctuation range exceeds 5 m. Table 7 is a table showing an example of satellite information (distance error amount) with a 1-second period for the past 3 minutes of satellite number 6.

  As shown in Table 7, the pseudorange error of this satellite is 1.2 m when the error is the smallest, but the maximum error is 6.3 m. Therefore, although it can be said that the quality of the satellite 6 is good instantaneously, the satellite 6 is excluded because it is considered that the error is likely to occur.

  In the above description, the extension of the fourth embodiment has been described. However, in the case of the extension of the first to third embodiments, the high-priority satellite combination information generation unit 19 of the reference station 11 performs, for example, a 1-second cycle for the past 3 minutes. Thus, satellites with a fluctuation range exceeding 5 m are excluded.

  According to the seventh embodiment, it is possible to eliminate satellites at positions where multipath errors are likely to occur even if position information with high accuracy is obtained instantaneously and looks good at first glance. Improves. In general, errors due to factors other than multipath change slowly, so if the pseudo-range and position information change drastically at the reference station, the cause of the error is likely to be multipath. For this reason, there are cases where the satellite is in a position where a multipath error is likely to occur even if position information with high accuracy is obtained momentarily. Since satellites at positions where such multipath errors are likely to occur can be excluded, the stability of position calculation is improved.

  Next, Example 8 will be described. In the eighth embodiment, the high-priority satellite combination information generation unit 19 of the reference station 11 or the high-priority satellite information generation unit 34 holds satellite observation data for the past one day or more, and selects a multipath satellite or a combination of satellites. It is something to be excluded.

  Since the satellite 14 is configured to go around a fixed orbit around the earth approximately once a day, it is possible to predict the arrangement of the satellite 14 to some extent. Accordingly, if the reference station 11 accumulates data for a long time (for example, for three months), it can be predicted which satellite multipath error is small at which time. In this way, a database of which area and which satellite should be selected at which time and if it is installed in the on-board device 23, the communication between the base station 11 and the on-board device 23 can be performed without communication. A satellite with a small path error can be selected.

  According to the eighth embodiment, it is possible to select the satellite 14 in which the multipath error is reduced only by the onboard device 23 without performing communication between the reference station 11 and the onboard device 23.

DESCRIPTION OF SYMBOLS 11 ... Base station, 12 ... Track, 13 ... Train, 14 ... Satellite, 15 ... Satellite signal receiving part, 16 ... Satellite signal temporary storage part, 17 ... Satellite combination selection part, 18 ... Position information calculation part, 19 ... High priority Satellite combination information generation unit, 20 ... True position information storage unit, 21 ... High priority satellite combination information storage unit, 22 ... Ground vehicle on-board transmission device,

23: On-board device, 24: Ground vehicle transmission device, 25 ... High priority satellite combination information storage unit, 26 ... Satellite combination selection unit, 27 ... Satellite signal reception unit, 28 ... Position calculation unit,

DESCRIPTION OF SYMBOLS 29 ... Central apparatus, 30 ... Correction position calculation part, 31 ... Pseudo distance correction information storage part, 32 ... Pseudo distance calculation part, 33 ... Geometric distance calculation part, 34 ... High priority satellite information generation part, 35 ... High priority satellite information storage unit 36 ... High priority satellite information storage unit 37 37 Satellite selection unit 38 38 Pseudo distance correction unit

Claims (8)

In a train position detection system comprising one or more reference stations installed on the ground for receiving satellite signals from satellites and on-board devices mounted on one or more trains,
The reference station is
A satellite signal receiver for receiving satellite signals from the satellite;
A satellite combination selection unit that selects a predetermined number of satellite combinations from the satellite signals received by the satellite signal reception unit;
A position information calculation unit for calculating the position of the reference station from the satellite signal selected by the satellite combination selection unit;
A combination of satellites with a small error between the position calculated by the position information calculation unit and a predetermined true position of the reference station is determined, and high-priority satellite combination information that is a list of satellite combinations with a small error is generated. A high-priority satellite combination information generation unit;
A ground-on-vehicle transmission device for transmitting the high priority satellite combination information generated by the high priority satellite combination information generation unit to the train,
The on-board device of the train is
A satellite signal receiver for receiving satellite signals from the satellite;
An on-vehicle transmission device for receiving high-priority satellite combination information generated by the reference station;
A satellite combination selection unit that selects a satellite combination with a small position error from satellite signals received by the satellite signal reception unit using high priority satellite combination information received by the ground vehicle transmission device;
A train position detection system comprising: a position calculation unit that calculates a position of a train based on a satellite signal received by the satellite signal reception unit using a satellite signal selected by the satellite combination selection unit. The high-priority satellite combination information generation unit of the reference station includes not only the satellite combination having a small position error but also the position error magnitude and the direction of the error of each satellite combination in the high-priority satellite combination information. Sent to the train via the on-board transmission device,
The on-board device of the train includes a correction position calculation unit that calculates the train position by correcting the calculation result calculated by the position calculation unit by the magnitude and direction of the position error obtained by the reference station. The train position detection system according to claim 1.   The reference station includes a pseudo distance correction information storage unit for storing pseudo distance correction information obtained by using the DGPS function, and the position information calculation unit of the reference station is stored in the pseudo distance correction information. The train position detection system according to claim 1, wherein the position of the reference station is calculated based on pseudo distance correction information. In a train position detection system comprising one or more reference stations installed on the ground for receiving satellite signals from satellites and on-board devices mounted on one or more trains,
The reference station is
A satellite signal receiver for receiving satellite signals from the satellite;
A pseudo-range calculator that calculates a pseudo-range between the satellite and the reference station based on a satellite signal received by the satellite signal receiver;
A geometric distance calculation unit for calculating a geometric distance from a satellite position that can be grasped from the satellite signal and a predetermined true position of the reference station;
A satellite having a small difference between the pseudo distance calculated by the pseudo distance calculating unit and the geometric distance calculated by the geometric distance calculating unit is determined, and high priority satellite information which is a list of the small differences is generated. A high-priority satellite information generation unit,
An on-vehicle transmission device for transmitting high priority satellite information generated by the high priority satellite information generation unit to a train,
The on-board device of the train is
A satellite signal receiver for receiving satellite signals from the satellite;
An on-vehicle transmission device for receiving high-priority satellite information generated by the reference station;
A satellite selection unit that selects a satellite with a small pseudorange from satellite signals received by the satellite signal reception unit using high priority satellite information received by the ground vehicle transmission device;
A train position detection system comprising: a position calculation unit that calculates a position of a train based on a satellite signal received by the satellite signal reception unit using a satellite signal selected by the satellite selection unit.   The high priority satellite information generation unit of the reference station includes not only a list of satellites in which the difference between the pseudorange and the geometric distance is small, but also the magnitude of the pseudorange error of the satellite in the high priority satellite information. Transmitting to the train via the on-vehicle transmission device, the on-vehicle device of the train includes a pseudo distance correction unit that corrects only the magnitude of the pseudo distance error transmitted from the reference station, and the position calculation 5. The train position detection system according to claim 4, wherein the unit calculates the train position in consideration of the pseudo distance error corrected by the pseudo distance correction unit.   The reference station includes a pseudo distance correction information storage unit that stores pseudo distance correction information obtained using the DGPS function, and the pseudo distance calculation unit of the reference station calculates a pseudo distance between the satellite and the reference station. The train position detection system according to claim 4 or 5, wherein the train position detection system is calculated.   The high-priority satellite combination information generation unit of the reference station or the high-priority satellite information generation unit of the reference station holds short-time satellite observation data within the past day and is frequently affected by multipath. The train position detection system according to any one of claims 1 to 6, wherein a satellite or a combination of satellites is excluded.   The high-priority satellite combination information generation unit of the reference station or the high-priority satellite information generation unit of the reference station holds satellite observation data for the past day or more and excludes multipath satellites or combinations of satellites. The train position detection system according to claim 1.

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