JP2011085524A - Position detection system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a position detection system that reliably detects the position of a vehicle, even when the vehicle is under the ground and prevents a drop of detection accuracy due to disturbance waves. <P>SOLUTION: In the position detection system, when instructions of position detection are input by a terminal 2, a microcomputer 209 acquires azimuth information concerning the direction of the terminal 2 and transmits the azimuth information to an onboard device 1. The onboard device 1 switches directional antennas 104-107 by time sharing to receive signals, and an SS radio 103 despreads the received signals of the directional antennas 104-107 to determine a relative peak value. The microcomputer 109 determines the direction of the terminal 2 on the basis of the relative peak value, and specifies the azimuth of the terminal 2, referring to a magnetic azimuth sensor 101. Furthermore, it determines detection direction indicating the direction of viewing the onboard device 1 from the terminal 2 on the basis of the azimuth information received from the terminal 2 and the specified azimuth, and transmits the detection direction information to the terminal 2. The terminal 2 displays the direction of the onboard device 1 on a display 206 on the basis of the received information. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a position detection device that detects the position of an object, and more particularly to a position detection system that can reliably perform position detection even when there is an interference wave.

[Description of Prior Art]
As a position detection system that finds cars in large parking lots and multilevel parking lots, a system that uses GPS (Global Positioning System) information acquired by in-vehicle devices to inform the user's mobile terminal of the vehicle position (patent) There are some which display the direction and distance of the vehicle on the terminal based on the received signal strength (RSSI) of the signal transmitted from the in-vehicle device (see Patent Literature 1) (see Patent Literature 2).

In addition, there is a technique that prevents detection of a peak signal caused by noise by changing and setting a detection threshold value of a reception level based on an average value of a frequency spectrum in a noise region (Patent Document 3). reference).
In addition, in order to prevent traffic accidents, in-vehicle devices send location information requests to pedestrian terminals, and pedestrian terminals send location information as a response. Frequency hopping time division is used as a communication method. There was one using a spread spectrum communication system based on a multiplex communication system (see Patent Document 4).

JP 2004-046146 A JP 2008-015801 A JP 2004-0669467 A JP 2005-184330 A

  However, the conventional position detection system using GPS information has a problem in that it is inconvenient because it cannot receive radio waves from GPS satellites when the vehicle is underground.

  In addition, in the conventional position detection system that determines the direction and distance using RSSI (reception level), if there is an interference wave, the reception level of the interference wave also reacts, so the detection accuracy deteriorates. There was a problem of end.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a position detection system that can reliably detect a position even in the underground and can prevent a decrease in detection accuracy due to an interference wave. To do.

  The present invention for solving the problems of the conventional example described above is a position detection system that includes an in-vehicle device mounted on a vehicle or the like and a terminal carried by a user, and displays the position of the vehicle or the like on the terminal. The in-vehicle device obtains a plurality of directional antennas having different directivities, a first wireless device that performs spread spectrum communication, a first magnetic direction sensor that detects an orientation, and information to be transmitted to the terminal. A control unit, and a terminal for inputting an instruction by a user, a second radio for performing spread spectrum communication, a second magnetic direction sensor for detecting a direction, and a display for displaying information And a control unit that controls display on the display, and when the control unit of the terminal inputs an instruction to detect the position of the in-vehicle device from the input unit, Orientation information that indicates whether you are facing Obtaining and transmitting the azimuth information to the in-vehicle device via the second wireless device, and the first wireless device of the in-vehicle device receives signals from a plurality of directional antennas in a time division manner and despreading each To calculate the correlation peak value for each directional antenna, the control unit of the in-vehicle device determines the direction in which the terminal exists based on the calculated plurality of correlation peak values, and based on the first magnetic direction sensor The direction of the determined direction is specified, and based on the direction information of the terminal and the specified direction included in the received signal, detection direction information indicating the direction of viewing the in-vehicle device from the terminal is obtained, and the detection direction information Is transmitted to the terminal via the first radio, and the control unit of the terminal displays information indicating the direction in which the in-vehicle device is present on the display based on the received detection direction information.

  Further, the present invention is characterized in that, in the position detection system, the control unit of the in-vehicle device determines the direction of the terminal based on a ratio of correlation peak values of received signals from a plurality of directional antennas.

  According to the present invention, in the position detection system, the in-vehicle device includes a first atmospheric pressure sensor, the terminal includes a second atmospheric pressure sensor, and the control unit of the terminal receives atmospheric pressure information from the second atmospheric pressure sensor. Acquired and transmitted to the in-vehicle device together with the direction information, the control unit of the in-vehicle device acquires the atmospheric pressure information from the first atmospheric pressure sensor, and based on the atmospheric pressure information of the terminal included in the received signal and the acquired atmospheric pressure information The height difference between the location where the terminal and the in-vehicle device are located is calculated and transmitted to the terminal together with the detection direction information as height information, and the control unit of the terminal It is characterized by displaying information indicating the difference in height between the place where the in-vehicle device and the terminal are located.

  Further, according to the present invention, in the position detection system, the control unit of the in-vehicle device is configured so that the terminal faces the azimuth of the identified terminal based on a difference between the azimuth information of the terminal and the identified azimuth of the terminal. Is transmitted as detection direction information, and the control unit of the terminal receives the detection direction information and displays an arrow indicating the detection direction on the display.

  Further, according to the present invention, in the position detection system, the control unit of the in-vehicle device transmits the specified terminal orientation as detection direction information, and the terminal control unit receives the detection direction information, Based on the azimuth information from the magnetic azimuth sensor, an arrow indicating the direction facing the detection direction is displayed on the display.

  According to the present invention, an in-vehicle device includes a plurality of directional antennas having different directivities, a first radio that performs spread spectrum communication, a first magnetic direction sensor that detects an orientation, and a terminal. And a control unit that obtains information to be transmitted. The terminal includes an input unit through which a user inputs an instruction, a second radio that performs spread spectrum communication, a second magnetic direction sensor that detects an orientation, and information. And a control unit that controls display on the display unit. When the control unit of the terminal receives an instruction to detect the position of the in-vehicle device from the input unit, the second magnetic direction sensor Direction information indicating which direction the terminal is facing from is transmitted to the in-vehicle device via the second radio, and the first radio of the in-vehicle device has a plurality of directivities. Receive the signal from the antenna in time division, The first magnetic direction sensor calculates the correlation peak value for each directional antenna by performing despreading, and the controller of the in-vehicle device determines the direction in which the terminal exists based on the calculated plurality of correlation peak values. The direction of the determined direction is identified based on the terminal, and detection direction information indicating the direction of viewing the in-vehicle device from the terminal is obtained and detected based on the direction information of the terminal included in the received signal and the identified direction. As a position detection system that transmits direction information to the terminal via the first radio, and the control unit of the terminal displays information indicating the direction in which the in-vehicle device is present on the display based on the received detection direction information. Therefore, in the in-vehicle device, by determining the direction of the terminal based on the correlation level, it is possible to prevent erroneous detection of the direction of the terminal even when an interference wave having a high electric field level is received. underground There can also be detected, there is an effect that it is possible to perform highly accurate position detection.

  Further, according to the present invention, since the control unit of the in-vehicle device is the position detection system that determines the direction of the terminal based on the ratio of the correlation peak values of the received signals from the plurality of directional antennas, Even when the antenna exists in the direction between the two directional antennas, there is an effect that the direction of the terminal can be accurately determined.

  According to the present invention, the in-vehicle device includes the first atmospheric pressure sensor, the terminal includes the second atmospheric pressure sensor, and the control unit of the terminal acquires the atmospheric pressure information from the second atmospheric pressure sensor, The direction information is transmitted to the in-vehicle device, and the control unit of the in-vehicle device acquires the atmospheric pressure information from the first atmospheric pressure sensor, and based on the atmospheric pressure information of the terminal included in the received signal and the acquired atmospheric pressure information, The height difference of the place where the in-vehicle device is located is calculated and transmitted as height information to the terminal together with the detection direction information, and the control unit of the terminal is based on the received height information on the display device. Since the position detection system displays the information indicating the height difference of the place where the vehicle is located, the user can infer which floor the target vehicle is parked from the height difference information. You can easily see the target vehicle in the multistory parking lot. There is an effect that can be issued only.

  Further, according to the present invention, the control unit of the in-vehicle device detects the direction in which the terminal faces the specified terminal direction based on the difference between the terminal direction information and the specified terminal direction. And the control unit of the terminal receives the detection direction information and displays the arrow indicating the detection direction on the display unit. Therefore, the processing of the terminal is reduced and the configuration is simplified. In addition, there is an effect that the user can intuitively recognize the direction of the in-vehicle device and easily find the target vehicle.

  Further, according to the present invention, in the position detection system, the control unit of the in-vehicle device transmits the specified terminal orientation as detection direction information, and the terminal control unit receives the detection direction information, Based on the azimuth information from the magnetic azimuth sensor, the position detection system displays an arrow indicating the direction facing the detection direction on the display, so that the user can intuitively recognize the direction of the in-vehicle device. There is an effect that the target vehicle can be easily found.

1 is a block diagram of a schematic configuration of a position detection system according to a first embodiment of the present invention. FIG. 10 is a flowchart showing processing in the microcomputer 209 of the terminal 2. It is a flowchart figure which shows the process in the microcomputer 109 of the vehicle equipment 1. It is model explanatory drawing which shows the detection in an electric field level, and the detection in a correlation value level. It is explanatory drawing which shows an example in case an interference wave source is near the vehicle equipment.

[Outline of the embodiment]
Embodiments of the present invention will be described with reference to the drawings.
A position detection system according to an embodiment of the present invention includes an in-vehicle device and a terminal, a magnetic direction sensor, an atmospheric pressure sensor, and a spread spectrum communication system radio, and the in-vehicle device includes a plurality of directional antennas, When the terminal detects the position of the vehicle, it transmits azimuth information indicating which direction the terminal is facing and atmospheric pressure information, and the in-vehicle device receives the received signal from the terminal with each directional antenna. Then, the direction in which the terminal exists is determined by detecting and comparing the correlation peak value in each antenna, the direction of the terminal is identified with reference to the direction sensor, and the terminal determined to be the received direction information The vehicle detection direction information (for correcting the orientation of the terminal) indicating the direction of the vehicle-mounted device viewed from the terminal is obtained based on the direction of the terminal, and the received atmospheric pressure information and the atmospheric pressure measured by the own atmospheric pressure sensor are obtained. Compared to the difference, the system obtains the difference in altitude from the terminal, sends vehicle detection direction information and altitude difference information to the terminal, and displays it on the terminal. Detection can be performed.

[First Embodiment: FIG. 1]
The configuration of the position detection system according to the first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic configuration block diagram of a position detection system according to a first embodiment of the present invention.
As shown in FIG. 1, the position detection device according to the first embodiment includes an in-vehicle device 1 mounted on a vehicle or the like as an object whose position is detected, and a terminal 2 carried by the user. Is done.

[Configuration of in-vehicle device 1: Fig. 1]
The in-vehicle device 1 includes directional antennas 104, 105, 106, 107, a switch 108, an SS radio device 103, a microcomputer 109, a magnetic direction sensor 101, and an atmospheric pressure sensor 102.

The directional antennas 104 to 107 have directivity directed in the front-rear and left-right directions of the vehicle body, receive radio signals from a specific direction, and transmit radio signals in a specific direction.
The switch 108 switches and receives the reception signals of the directional antennas 104 to 107 in a time division manner, and switches the transmission signal output destination to the directional antennas 104 to 107 for transmission.

The SS radio 103 is a radio that performs spread spectrum communication with the terminal 2 and transmits the transmission data by spreading it over a wide frequency band using a spreading code. At the time of reception, the despreading code corresponding to the spreading code on the transmission side Is used for decoding.
The SS radio 103 of the in-vehicle device 1 of this system despreads the received signals from the directional antennas 104 to 107, detects the correlation peak value for each antenna, and outputs it to the microcomputer 109. The SS wireless device 103 stores its own ID and the ID of the communication destination terminal 2 in advance. If the destination ID in the received signal matches the own ID, the received data is acquired. When transmitting to the terminal 2, the ID of the terminal 2 is attached as a destination and transmitted.

  The microcomputer 109 performs processing that characterizes the present system, detects the direction of the terminal 2 based on the correlation peak value for each directional antenna input from the SS radio 103, and detects the terminal based on the atmospheric pressure information. 2 is detected, and a process of transmitting information indicating the difference between the direction and height of the vehicle-mounted device 1 viewed from the terminal 2 to the terminal 2 is performed. The processing of the microcomputer 109 will be described in detail later.

The magnetic azimuth sensor 101 is a general azimuth sensor. In the in-vehicle device 1 of this system, the azimuth indicating the central direction of the directivity of each directional antenna 104 to 107, that is, here, the front / rear / right / left azimuth of the vehicle body is specified. To do. Information on the orientation of the magnetic orientation sensor is used by the microcomputer 109 to identify which orientation the direction of the terminal 2 detected based on the correlation peak value corresponds to.
The atmospheric pressure sensor 102 measures the ambient atmospheric pressure. The in-vehicle device 1 of this system is used as information for calculating the difference between the height of the place where the terminal 2 is located and the height of the place where the on-vehicle device 1 is located.

[Configuration of Terminal 2: FIG. 1]
The terminal 2 includes an antenna 204, an SS radio 203, a microcomputer 209, a display 206, a magnetic direction sensor 201, and an atmospheric pressure sensor 202. Although not shown in the figure, an input unit for a user to input an instruction is provided.
The antenna 204 transmits and receives radio signals.
The SS radio 203 is a radio that performs spread spectrum communication with the in-vehicle device 1. Similar to the SS radio 103 of the in-vehicle device 1, the SS radio 203 of the terminal 2 also stores in advance the own ID and the ID of the in-vehicle device 1 that is the communication destination, and the destination ID in the received signal at the time of reception is Received data is acquired when it matches with its own ID, and the ID of the in-vehicle device 1 is attached as a destination at the time of transmission.

The magnetic azimuth sensor 201 outputs azimuth information indicating the direction of the terminal 2 as to which direction it is facing. For example, normally, the upward direction of the display 206 is the orientation of the terminal 2.
The atmospheric pressure sensor 202 measures atmospheric pressure.
The microcomputer 209 transmits the azimuth information and the atmospheric pressure information from the SS wireless device 203 to the in-vehicle device 1 in accordance with an instruction from the input unit. Further, based on the data received from the in-vehicle device 1, the display 206 displays information indicating the direction of the in-vehicle device 1 viewed from the terminal 2 and information indicating the height difference between the terminal 2 and the in-vehicle device 1. To do. The operation of the microcomputer 209 will be described later in detail.

[Operation of this system: Fig. 1]
Next, the operation of this system will be described with reference to FIG.
In the in-vehicle device 1, the directional antennas 104 to 107 are switched by the switch 108 in a time division manner to perform the receiving operation.
The terminal 2 is normally in a non-operating state. However, when an instruction for detecting the position of the object is input from the input unit, the microcomputer 209 acquires the atmospheric pressure information from the atmospheric pressure sensor 202 and the magnetic orientation sensor 201 from the terminal device. The azimuth information indicating which azimuth (direction) the upper part of the display 206 is facing is acquired, and the atmospheric pressure information and the azimuth information are transmitted to the in-vehicle device 1 via the SS radio 203.

Here, the transmission time from the terminal 2 is equal to or longer than the time for switching all the directional antennas 104 to 107 in the in-vehicle device 1. Thereby, in the vehicle-mounted apparatus 1, the same data can be received with all the directional antennas 104-107.
Then, the SS radio 203 of the terminal 2 performs a reception operation for a certain time after transmission.

  If wireless communication is not established due to a poor communication status or the like and no response is received from the in-vehicle device 1 within a certain time, the microcomputer 209 of the terminal 2 times out and returns to the non-operating state. At this time, a message notifying the user that the radio signal has not been established may be displayed on the display 206. As a result, the user can move to a place with better communication status and perform the detection operation again.

The in-vehicle device 1 receives transmission signals from the terminal 2 by the directional antennas 104 to 107.
Then, the SS radio 103 despreads the received signals received by the directional antennas 104 to 107 to detect the correlation peak value and outputs it to the microcomputer 109.
The microcomputer 109 compares the correlation peak values of the directional antennas 104 to 107 to determine the direction in which the terminal 2 exists.

Here, it is conceivable that the microcomputer 109 determines the ratio of the correlation peak values of the directional antennas 104 to 107 and determines the direction of the terminal 2 based on the ratio.
For example, when the correlation peak value of a certain directional antenna is very large compared to the other (1: 0: 0: 0), the microcomputer 109 causes the terminal 2 to point in the direction of the directional antenna having a large correlation peak value. It is determined that it exists.
Further, when the correlation peak values of the two directional antennas are substantially equal (in the case of 1: 1: 0: 0), it is determined that the terminal 2 exists in the middle direction between the two directional antennas.

  Then, the microcomputer 109 refers to the azimuth information from the magnetic azimuth sensor 101 and identifies which azimuth (east, west, south, north, and azimuth between them) corresponds to the determined direction of the terminal 2. The direction specified here is information indicating the direction of the terminal 2 viewed from the in-vehicle device 1.

  Then, the microcomputer 109 obtains information (detection direction information) indicating the direction of the in-vehicle device 1 viewed from the terminal 2 based on the orientation information of the terminal 2 included in the received data and the identified orientation of the terminal 2. To the terminal 2. As detection direction information, for example, an arrow indicating the direction in which the in-vehicle device 1 is viewed from the terminal 2 (in which direction the in-vehicle device 1 is viewed from the terminal 2) can be considered.

The detection direction information will be described with a specific example.
For example, when the orientation of the terminal 2 specified by the in-vehicle device 1 is “south”, since the terminal 2 is on the south side of the in-vehicle device 1, the terminal 2 is in the opposite direction (azimuth shifted by 180 degrees). It is desirable to receive direction information of “north”.
As described above, when the direction of the terminal 2 identified as “north” from the terminal 2 is “south”, that is, when the received direction information directly faces the identified direction, the terminal 2 Indicates the direction of the in-vehicle device 1 almost accurately, for example, as the detection direction information, an upward arrow indicating that the current direction may be maintained is transmitted.

Further, when the orientation information of the terminal 2 is “north” and the orientation of the specified terminal 2 is “east”, the terminal 2 is located on the east side of the in-vehicle device 1 but faces north. In this case, since the azimuth information of the terminal 2 is deviated 90 degrees clockwise from the desired azimuth (here, “west” directly facing “east”), the in-vehicle device 1 detects the detection direction so as to correct it. As information, a left arrow is transmitted by shifting the upward arrow 90 degrees counterclockwise.
As described above, the microcomputer 109 of the in-vehicle device 1 generates detection direction information for directing the terminal 2 in a desired direction based on the difference between the received azimuth information of the terminal 2 and the azimuth of the terminal 2 specified in the in-vehicle device 1. It comes to ask for.

  Further, the microcomputer 109 of the in-vehicle device 1 compares the atmospheric pressure information of the terminal 2 included in the received data with the atmospheric pressure information from the atmospheric pressure sensor 102, calculates a difference in height, and sends the height information to the terminal 2 as height information. Send. If the difference in the atmospheric pressure information is within the accuracy error of the atmospheric pressure sensor, it may be determined that the height is the same. The conversion from the atmospheric pressure information to the altitude is performed based on a general calculation formula.

When the terminal 2 receives the detection direction information and the height information from the in-vehicle device 1, the microcomputer 209 displays an arrow indicating the direction of the in-vehicle device 1 viewed from the terminal 2 on the display 206 based on the received data, and the height. Information (for example, −10 m, +5 m, etc.) is displayed.
The user can determine which floor the target vehicle is based on the difference in height, and can recognize the direction of the vehicle based on the arrow of the detection direction information.

  For example, when the terminal 2 receives and displays a left-pointing arrow as detection direction information, it can be seen that the user should turn 90 degrees left from the current direction as indicated by the arrow. Similarly, the detection direction information may be directed to the right if it is a right-pointing arrow, and may be directed to the opposite direction if it is a downward-pointing arrow. In the case of an arrow in an oblique direction, the direction indicated by the arrow may be turned in the same manner, and the display allows the user to intuitively recognize the direction of the in-vehicle device 1.

  Thus, in this system, since the direction of the vehicle-mounted device 1 viewed from the terminal 2 is calculated by the microcomputer 109 of the vehicle-mounted device 1 and transmitted to the terminal 2, the received information is received on the terminal 2 side. What is necessary is just to display as it is, and the process in the terminal 2 can be reduced and a structure can be simplified.

  Note that the terminal 2 displays the east, west, south, and north directions based on the information of the magnetic direction sensor 201, and the in-vehicle device 1 determines the direction of the terminal 2 specified from the correlation peak value and the information of the direction sensor 101. It is also possible to configure the terminal 2 so that the terminal 2 obtains the direction of the in-vehicle device 1 viewed from the terminal 2, that is, the direction directly opposite to the received direction based on the received direction and displays it. is there.

[Processing of the microcomputer 209 of the terminal 2: FIG. 2]
Next, processing in the microcomputer 209 of the terminal 2 will be described with reference to FIG. FIG. 2 is a flowchart showing processing in the microcomputer 209 of the terminal 2.
When a position detection instruction is input from the input unit (100), the microcomputer 209 of the terminal 2 acquires atmospheric pressure information from the atmospheric pressure sensor 202 (102), and acquires azimuth information indicating the orientation of the terminal 2 from the magnetic sensor 201. (104), and transmits the atmospheric pressure information and the azimuth information to the in-vehicle device 1 via the SS wireless device 203 (106).

Then, the microcomputer 209 causes the SS radio 203 to start a reception operation, determines whether or not a signal from the in-vehicle device 1 has been received (108), and if not, determines whether or not the time is up. (110) If the time is not up, the process returns to the process 108 and the reception operation is continued.
When the time is up in the process 110, the fact that the time is up is displayed (112), and the process ends.

  Further, when the signal from the in-vehicle device 1 is received in the process 108, the detection direction information and the height information are acquired from the received data, and based on these, the detection direction of the in-vehicle device 1 viewed from the terminal 2 and The difference in height is displayed on the display 206 (114). In this way, the processing of the microcomputer 209 of the terminal 2 is performed.

[Process of the microcomputer 109 of the in-vehicle device 1: FIG. 3]
Next, processing of the microcomputer 109 of the in-vehicle device 1 will be described with reference to FIG. FIG. 3 is a flowchart showing processing in the microcomputer 109 of the in-vehicle device 1.
In the in-vehicle apparatus 1, the SS radio device 103 is intermittently receiving, and when receiving a signal from the terminal 2 (200), the microcomputer 109 acquires the correlation peak value and reception data for each directional antenna from the SS radio device 103. (202).

  Then, the microcomputer 109 determines the direction in which the terminal 2 exists based on the ratio of the correlation peak values (204), and specifies the direction of the determined direction based on the magnetic direction sensor 101 (206).

Further, the microcomputer 109 obtains a detection direction indicating the direction of viewing the in-vehicle device 1 from the terminal 2 based on the received azimuth information of the terminal 2 and the azimuth specified in the process 206 (208).
The microcomputer 109 acquires atmospheric pressure information from the atmospheric pressure sensor 102 (210), and obtains a difference in height based on the difference between the received atmospheric pressure information of the terminal 2 and the acquired atmospheric pressure information (212).
Then, the microcomputer 109 transmits detection direction information and height information indicating a difference in height to the terminal 2 via the SS radio device 103 (214).
In this way, the processing of the microcomputer 103 of the in-vehicle device 1 is performed.

[Detection at electric field level (RSSI) and detection at correlation value level: FIG. 4]
Next, a case where detection is performed at the electric field level and a case where detection is performed at the correlation value level will be described with reference to FIG. FIG. 4 is a schematic explanatory diagram showing detection at the electric field level and detection at the correlation value level.
As shown in FIG. 4A, in the in-vehicle device 1, when the received electric field level of the disturbing wave is higher than the electric field level of the spread spectrum received wave, the terminal is detected based on the electric field level. If the terminal is in the direction of the disturbing wave having a higher electric field level, it will be erroneously recognized.
As interference waves, radio waves of other communication devices using the same frequency band as the communication of this system, peripheral electronic device noise, and the like can be considered.

Therefore, by performing despreading processing at the time of reception, as shown in (b), the received wave has a correlation peak with a high correlation value level, whereas the interference wave is diffused without obtaining a correlation peak. Thus, the correlation value level is lowered.
As a result, even if the reception electric field level of the interference wave is strong, the influence can be reduced and erroneous detection of the direction of the terminal can be prevented.

[When there is an interference wave: Fig. 5]
Next, a case where there is an interference wave in this system will be described with reference to FIG. FIG. 5 is an explanatory diagram showing an example in the case where the interference wave source is near the vehicle-mounted device.
As shown in FIG. 5, when the terminal 2 is in the direction of the directional antenna 106 and the disturbing wave source 3 that generates the disturbing wave is in the direction of the directional antenna 104, as shown in FIG. When trying to detect the terminal 2 by making a comparison, the electric field level of the disturbing wave from the disturbing wave source 3 becomes larger, and it may be erroneously detected that the terminal 2 is in the direction of the disturbing wave source 3.

  However, in this system, since the microcomputer 109 of the in-vehicle apparatus 1 determines the correlation peak value of the received signal from each directional antenna, the correlation is obtained from the received signal of the directional antenna 104 that is the interference wave direction. A peak is not detected, and there is no false detection.

In addition, in the above-described Patent Document 2, it is also described that the direction of a frequency with a large received electric field level is detected as the direction of the terminal by changing the frequency little by little for each directional antenna. If there is a disturbing wave source with a strong electric field level in a different direction from the terminal, it will be erroneously detected.
In this system, even if the frequency is changed for each directional antenna, it is possible to prevent erroneous detection due to an interference wave by detecting the direction of the terminal using the correlation peak value.

[Effect of the embodiment]
According to the position detection system according to the embodiment of the present invention, when a position detection instruction is input from the input unit of the terminal 2, the microcomputer 209 acquires direction information indicating the direction of the terminal 2 from the magnetic direction sensor 201. Then, the atmospheric pressure information is acquired from the atmospheric pressure sensor 202, and the azimuth information and the atmospheric pressure information are transmitted from the SS radio 103 to the in-vehicle device 1. In the in-vehicle device 1, the directional antennas 104 to 107 are switched in a time division manner and the signal is transmitted. The SS radio 103 receives the signal from each of the directional antennas 104 to 107 and obtains a correlation peak value, the microcomputer 109 determines the direction of the terminal 2 based on the correlation peak value, and further magnetically The orientation of the terminal 2 is identified with reference to the orientation sensor 101, and a detection direction indicating the direction of viewing the in-vehicle device 1 from the terminal 2 is obtained from the orientation information received from the terminal 2 and the identified orientation. Obtains atmospheric pressure information from the sensor 102, calculates the difference in height from the difference from the received atmospheric pressure information, transmits detection direction information and height information to the terminal 2, and the terminal 2 based on the received information The difference between the direction and the height of the in-vehicle device 1 is displayed on the display 206, and when detecting the direction of the terminal 2 by the in-vehicle device 1, the correlation peak value of SS communication is used. Compared to the use, it is less susceptible to disturbing waves, can prevent erroneous detection of the direction of the terminal 2, can be detected even when the vehicle is underground, and further provides height direction information Thus, there is an effect that position detection with high accuracy can be performed.

  Further, according to the present system, the direction in which the in-vehicle device 1 is viewed from the terminal 2 is indicated by an arrow as the detection direction, so that the user intuitively recognizes in which direction the in-vehicle device 1 is located. Thus, there is an effect that the terminal 2 can be directed in the correct direction and the target vehicle can be found in a short time.

  Further, according to the present system, since the in-vehicle device 1 obtains the detection direction information indicating the direction in which the in-vehicle device 1 is viewed from the terminal 2, it is not necessary to perform special processing in the terminal 2, and the device configuration There is an effect that can be simplified.

  In this system, the in-vehicle device 1 and the terminal 2 are provided with atmospheric pressure sensors, and the respective atmospheric pressures are measured to calculate the difference in height. However, only the direction information is obtained without providing the atmospheric pressure sensor. The configuration of the in-vehicle device 1 and the terminal 2 can be simplified.

  The present invention is suitable for a position detection system that can reliably perform position detection even when there is an interference wave.

  DESCRIPTION OF SYMBOLS 1 ... In-vehicle apparatus, 2 ... Terminal, 101, 201 ... Magnetic direction sensor, 102, 202 ... Pressure sensor, 103, 203 ... SS radio | wireless machine, 104, 105, 106, 107 ... Directional antenna, 108 ... Switch, 109, 209 ... Microcomputer, 204 ... Antenna, 206 ... Display

Claims (5)

A position detection system comprising an in-vehicle device mounted on a vehicle or the like and a terminal carried by a user, and displaying the position of the vehicle or the like on the terminal,
The in-vehicle device obtains a plurality of directional antennas having different directivities, a first wireless device that performs spread spectrum communication, a first magnetic direction sensor that detects an orientation, and information to be transmitted to a terminal. A control unit,
The terminal includes an input unit through which a user inputs an instruction, a second wireless device that performs spread spectrum communication, a second magnetic direction sensor that detects an orientation, a display that displays information, and the display And a control unit for controlling display on
When an instruction to detect the position of the in-vehicle device is input from the input unit, the control unit of the terminal acquires direction information indicating which direction the terminal is facing from the second magnetic direction sensor. , Transmitting the azimuth information to the in-vehicle device via the second radio,
The first radio of the in-vehicle device receives signals from the plurality of directional antennas in a time division manner, performs despreading to calculate a correlation peak value for each directional antenna,
The control unit of the in-vehicle device determines the direction in which the terminal exists based on the calculated plurality of correlation peak values, specifies the direction of the determined direction based on the first magnetic direction sensor, Based on the azimuth information of the terminal and the specified azimuth included in the received signal, detection direction information indicating a direction of viewing the in-vehicle device from the terminal is obtained, and the detection direction information is obtained from the first wireless device. To the terminal via
The position detection system, wherein the control unit of the terminal displays information indicating a direction in which the in-vehicle device is present on the display based on the received detection direction information.   The position detection system according to claim 1, wherein the control unit of the in-vehicle device determines the direction of the terminal based on a ratio of correlation peak values of received signals from a plurality of directional antennas. The in-vehicle device includes a first atmospheric pressure sensor,
The terminal comprises a second barometric sensor;
The control unit of the terminal acquires atmospheric pressure information from the second atmospheric pressure sensor and transmits it to the in-vehicle device together with direction information,
The control unit of the in-vehicle device acquires atmospheric pressure information from the first atmospheric pressure sensor, and the terminal and the in-vehicle device are positioned based on the atmospheric pressure information of the terminal included in the received signal and the acquired atmospheric pressure information. Calculating the height difference of the location to be sent to the terminal along with the detection direction information as height information,
The control unit of the terminal displays information indicating a difference in height between the in-vehicle device and a location where the terminal is located on a display based on the received height information. 2. The position detection system according to 2. Based on the difference between the terminal orientation information and the identified terminal orientation, the control unit of the in-vehicle device transmits, as detection direction information, a direction in which the terminal faces the identified terminal orientation,
The position detection system according to claim 1, wherein the control unit of the terminal receives the detection direction information and displays an arrow indicating the detection direction on a display. The control unit of the in-vehicle device transmits the direction of the identified terminal as detection direction information,
The control unit of the terminal receives the detection direction information and displays an arrow indicating a direction facing the detection direction on a display based on the direction information from the second magnetic direction sensor. The position detection system according to claim 1.

Images