JP6885697B2 - Positioning system and mobile station - Google Patents

Description

The present invention relates to a positioning system in which a mobile station calculates the position of its own station based on radio signals received from a plurality of fixed stations, and a mobile station included in the positioning system.

As a positioning system, there is GPS (Global Positioning System). In GPS, multiple satellites orbit the earth. Each of these satellites transmits a wireless signal to a mobile terminal such as a car navigation system or a mobile phone existing on the earth. These radio signals include orbit information of the satellite that is the transmission source, transmission time information indicating the transmission time at which transmission was performed, and the like.

When the mobile terminal receives the radio signal, the mobile terminal calculates the propagation time of the received radio signal based on the reception time at which the reception was performed and the transmission time indicated by the transmission time information included in the received radio signal. Then, the mobile terminal calculates the propagation distance of the received radio signal based on the calculated propagation time. The mobile terminal can calculate the position of the satellite at the time when the radio signal is transmitted, based on the orbit information included in the received radio signal.

The mobile terminal calculates the propagation distance and the position of the source satellite for each of the radio signals transmitted from at least four satellites among the plurality of satellites, and the mobile terminal calculates its own position based on the calculated propagation distance and position. Is calculated.

It is possible to realize an indoor positioning system by arranging a plurality of fixed stations that transmit radio signals indoors instead of a plurality of satellites. Patent Document 1 discloses a positioning system in which a cart moving in a room calculates its own position based on radio signals transmitted by a plurality of indoor GPSs arranged in the room.

Japanese Unexamined Patent Publication No. 2008-145383

In GPS, satellite transmitting antennas do not have directivity and simultaneously transmit radio signals in all directions. Therefore, when a plurality of fixed stations that transmit radio signals like satellites are arranged indoors, the mobile station moving in the room transmits a large number of wireless signals reflected by an object such as a wall surface or a shelf from one fixed station. Receive. Therefore, it is difficult for a mobile station to select a radio signal that travels straight from one fixed station and directly reaches its own station from a large number of radio signals received from this fixed station.

As a matter of course, the propagation distance of the radio signal that is reflected by the object and reaches the mobile station is longer than the propagation distance of the radio signal that reaches the mobile station directly from the source. Therefore, when the propagation distance of the radio signal reflected by the object is selected, the wrong position is calculated.

Further, in GPS, the carrier frequency of the radio signal transmitted by the satellite is 1575.42 MHz, and the carrier wave is a low frequency. Therefore, the straightness of the radio signal transmitted by the satellite is low. Therefore, when the radio signal is diffracted due to the presence of the object in the traveling direction, the radio signal spreads greatly along the object.

The propagation distance of the radio signal that has been diffracted and reached the mobile station is longer than the propagation distance of the radio signal that has traveled straight from the source and reached the mobile station directly. When GPS is applied to an indoor positioning system, there is a high probability that the diffracted radio signal will reach the mobile station. When the diffracted radio signal reaches the mobile station, an erroneous position is calculated as the position of the mobile station.
From the above, when GPS is applied as an indoor positioning system, there is a problem that there is a high probability that an erroneous position is calculated as the position of the mobile station.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a positioning system and a mobile station having a low probability of calculating an erroneous position.

The positioning system according to the present invention includes a plurality of fixed stations fixed at predetermined indoor positions, a mobile station moving in the room, and two shields existing in the room and shielding radio signals. Each of the plurality of fixed stations has a transmitter for transmitting a radio signal having a directional property and a high frequency carrier, and includes a reflector for reflecting a radio signal toward a shielded region between the stations. The station is a distance calculation unit that calculates the propagation distance from the transmission source to the reception unit for the reception unit that receives the radio signal transmitted by the transmission unit of the plurality of fixed stations and the radio signal received by the reception unit. A position calculation unit that calculates the position of the mobile station based on the propagation distances of a plurality of radio signals whose sources are different from each other, and a radio signal received by the reception unit. A time calculation unit that calculates the propagation time from the transmission source to the reception unit, and a radio signal propagated from the transmission unit of the fixed station to the reception unit when the mobile station is stopped at a predetermined position. The correction amount calculation unit for calculating the correction amount for correcting the propagation time calculated by the time calculation unit and the correction amount calculation unit calculated based on the propagation time of the above and the propagation time stored in advance. The distance calculation unit has a correction unit that corrects the propagation time calculated by the time calculation unit based on the correction amount, and an intrusion determination unit that determines whether or not the mobile station has invaded the shielded area. , the correction unit calculates the propagation distance on the basis of the propagation time corrected, the position calculating section, by the intrusion determination unit, when the mobile station is determined to have entered into the shielded area, the mobile It is characterized in that the position of the mobile station is calculated based on the traveling direction and the moving speed of the station.

In the present invention, each of the plurality of fixed stations is fixed at a predetermined indoor position. The mobile station moves indoors and receives radio signals from the transmitters of each of the plurality of fixed stations. The mobile station calculates the propagation distance from the source to the own station for the received radio signal. The mobile station calculates the position of its own station based on the propagation distances of a plurality of radio signals whose sources are different from each other.

For each of the plurality of fixed stations, the transmitter that transmits the radio signal has directivity. Therefore, the number of radio signals that are reflected by an object such as a wall surface or a shelf in the room and reach the mobile station is small. Further, the carrier wave of the radio signal transmitted by each of the plurality of fixed stations is high frequency. Therefore, the radio signal does not spread significantly due to diffraction, and the radio signal transmitted by each of the plurality of fixed stations has a high probability of traveling straight and reaching the mobile station directly. As a result, the mobile station has a low probability of calculating an erroneous position as its own position.
Further, for example, the radio signal includes transmission time information indicating the time when the radio signal was transmitted, and the mobile station uses the radio signal based on the time when the radio signal is received and the time when the radio signal is transmitted. Calculate the propagation time of. Here, the time included in the transmission time information is the time indicated by the clock unit of the fixed station that is the transmission source, and the time when the mobile station receives the radio signal is the time indicated by the clock unit of the mobile station. If the times indicated by the clocks of the fixed station and the mobile station do not match, an error will occur in the propagation time calculated by the mobile station. Therefore, the mobile station calculates a correction amount for correcting the propagation time, corrects the propagation time based on this correction amount, and calculates an accurate propagation distance of the radio signal based on the corrected propagation time.
When the mobile station is stopped at a predetermined position, the mobile station calculates the correction amount based on the propagation time propagated from the fixed station to the own station and the propagation time stored in advance.
There is a reflector in the room. The reflector reflects the radio signal towards the shielded area between the two shields. When it is determined that the mobile station has entered the shielded area, the position of the mobile station is calculated based on the traveling direction and moving speed of the mobile station.
The positioning system according to the present invention includes a plurality of fixed stations fixed at predetermined indoor positions, a mobile station moving in the room, and two shields existing in the room and shielding radio signals. Each of the plurality of fixed stations has a transmitter for transmitting a radio signal having a directional property and a carrier having a high frequency, and includes a reflector for reflecting a radio signal toward a shielded region between them. The station is a distance calculation unit that calculates the propagation distance from the transmission source to the reception unit for the reception unit that receives the radio signal transmitted by the transmission unit of the plurality of fixed stations and the radio signal received by the reception unit. A position calculation unit that calculates the position of the mobile station based on the propagation distances of a plurality of radio signals whose sources are different from each other, and a radio signal received by the reception unit. A time calculation unit that calculates the propagation time from the transmission source to the reception unit, and a correction for correcting the propagation time calculated by the time calculation unit when the mobile station is stopped at a predetermined position. The correction amount calculation unit that calculates the amount, the correction unit that corrects the propagation time calculated by the time calculation unit based on the correction amount calculated by the correction amount calculation unit, and the mobile station have invaded the shielded area. or and a whether determining intrusion determination unit, the distance calculation unit is configured to calculate the propagation distance on the basis of a propagation time correction unit is corrected, the correction amount calculation unit, the mobile station is the When the position is stopped at a predetermined position, the position calculated by the position calculation unit calculates a correction amount indicating the predetermined position. In the position calculation unit, the intrusion determination unit causes the mobile station to cover the shielding area. When it is determined that the mobile station has invaded the radio, the position of the mobile station is calculated based on the traveling direction and the moving speed of the mobile station .
In the present invention, each of the plurality of fixed stations is fixed at a predetermined indoor position. The mobile station moves indoors and receives radio signals from the transmitters of each of the plurality of fixed stations. The mobile station calculates the propagation distance from the source to the own station for the received radio signal. The mobile station calculates the position of its own station based on the propagation distances of a plurality of radio signals whose sources are different from each other.
For each of the plurality of fixed stations, the transmitter that transmits the radio signal has directivity. Therefore, the number of radio signals that are reflected by an object such as a wall surface or a shelf in the room and reach the mobile station is small. Further, the carrier wave of the radio signal transmitted by each of the plurality of fixed stations is high frequency. Therefore, the radio signal does not spread significantly due to diffraction, and the radio signal transmitted by each of the plurality of fixed stations has a high probability of traveling straight and reaching the mobile station directly. As a result, the mobile station has a low probability of calculating an erroneous position as its own position.
The mobile station also calculates the propagation time of the radio signal. The mobile station calculates a correction amount for correcting the calculated propagation time, corrects the calculated propagation time based on this correction amount, and calculates an accurate propagation distance of the radio signal based on the corrected propagation time. To do.
The mobile station calculates a correction amount in which the calculated position indicates a predetermined position when the own station is stopped at a predetermined position.
There is a reflector in the room. The reflector reflects the radio signal towards the shielded area between the two shields. When it is determined that the mobile station has entered the shielded area, the position of the mobile station is calculated based on the traveling direction and moving speed of the mobile station.

The positioning system according to the present invention is characterized in that the carrier wave is millimeter waves.

In the present invention, each of the plurality of fixed stations transmits a radio signal having a carrier wave of millimeter waves to the mobile station.

In the positioning system according to the present invention, the transmitting units of two or more fixed stations do not transmit the radio signal in the same time zone, and the transmitting unit that transmits the radio signal is changed over time. It is characterized by that.

In the present invention, two or more fixed stations do not transmit radio signals in the same time zone, and the fixed stations that transmit radio signals are changed over time. Therefore, a plurality of radio signals do not interfere with each other, and information contained in the radio signals, for example, information indicating a fixed station as a transmission source, is appropriately acquired in the mobile station.

The positioning system according to the present invention is characterized in that the transmission unit of each of the plurality of fixed stations continuously transmits the radio signal, and the transmission directions of the continuously transmitted radio signals are different from each other. To do.

In the present invention, each of the plurality of fixed stations continuously transmits a radio signal. At this time, each of the plurality of fixed stations changes the transmission direction of the radio signal over time. Therefore, there is a high probability that the radio signal transmitted by each of the plurality of fixed stations will be received by the mobile station.

In the positioning system according to the present invention, each of the plurality of fixed stations has a coding unit that encodes the baseband signal by spreading the spectrum of the baseband signal based on a predetermined code, and the coding. The mobile station further includes a generation unit that generates the radio signal by superimposing the coded signal encoded by the unit on the carrier, and the mobile station generates the coded signal from the radio signal received by the reception unit. It is characterized by having an extraction unit for extraction and a decoding unit for decoding the coded signal into the baseband signal by back-spreading the spectrum of the coded signal extracted by the extraction unit.

In the present invention, each of the plurality of fixed stations encodes the baseband signal by spreading the spectrum of the baseband signal based on a predetermined code, and superimposes the encoded coded signal on the carrier wave. By generating a radio signal. The mobile station extracts the coded signal from the received radio signal and despreads the spectrum of the extracted coded signal to decode the coded signal into a baseband signal. As described above, spectrum diffusion communication is performed between each of the plurality of fixed stations and the mobile station.

The mobile station according to the present invention is a mobile station that moves in a room in which a reflector that reflects the radio signal toward a shielding area between two shields that shields the radio signal is installed, and is a predetermined room. For a receiving unit that receives a radio signal transmitted from a plurality of fixed stations fixed at the position of, and having a high frequency carrier, and a radio signal received by the receiving unit, the propagation distance from the source to the receiving unit is determined. A position calculation unit for calculating the position of the mobile station and a reception unit for calculating the position of the mobile station based on the propagation distance of a plurality of radio signals whose transmission sources are different from each other and calculated by the distance calculation unit. A time calculation unit that calculates the propagation time from the source to the reception unit, and a radio that propagates from the fixed station to the reception unit when the mobile station is stopped at a predetermined position. Based on the signal propagation time and the propagation time stored in advance, the correction amount calculation unit that calculates the correction amount for correcting the propagation time calculated by the time calculation unit and the correction amount calculation unit calculate the correction amount. The distance calculation unit includes a correction unit that corrects the propagation time calculated by the time calculation unit based on the corrected amount, and an intrusion determination unit that determines whether or not the mobile station has invaded the shielded area. , the correction unit calculates the propagation distance on the basis of the propagation time corrected, the position calculating section, by the intrusion determination unit, when the mobile station is determined to have entered into the shielded area, the mobile It is characterized in that the position of the mobile station is calculated based on the traveling direction and the moving speed of the station.

In the present invention, radio signals transmitted from a plurality of fixed stations fixed at predetermined indoor positions are received. For the received radio signal, the propagation distance from the source to the receiving unit is calculated. The position of the own station is calculated based on the propagation distances of a plurality of radio signals whose sources are different from each other.
Since a radio signal having a high carrier wave is received from a plurality of fixed stations, there is a high probability that the radio signal traveling straight from the source will be received. As a result, the probability that an incorrect position is calculated as the position of the own station is low.
The mobile station also calculates the propagation time of the radio signal. The mobile station calculates a correction amount for correcting the calculated propagation time, corrects the calculated propagation time based on this correction amount, and calculates an accurate propagation distance of the radio signal based on the corrected propagation time. To do.
When the mobile station is stopped at a predetermined position, the mobile station calculates the correction amount based on the propagation time from the fixed station to the own station and the propagation time stored in advance.
A reflector is installed in the room. The reflector reflects the radio signal towards the shielded area between the two shields. When it is determined that the mobile station has entered the shielded area, the position of the mobile station is calculated based on the traveling direction and moving speed of the mobile station.
The mobile station according to the present invention is a mobile station that moves in a room in which a reflector that reflects a radio signal toward a shielding area between two shields that shields the radio signal is installed, and is a predetermined room. For a receiving unit that receives a radio signal transmitted from a plurality of fixed stations fixed at the position of, and having a high frequency carrier, and a radio signal received by the receiving unit, the propagation distance from the source to the receiving unit is determined. A position calculation unit for calculating the position of the mobile station and a reception unit for calculating the position of the mobile station based on the propagation distance of a plurality of radio signals whose transmission sources are different from each other and calculated by the distance calculation unit. For the radio signal received by, the time calculation unit that calculates the propagation time from the transmission source to the reception unit and the propagation time calculated by the time calculation unit when the mobile station is stopped at a predetermined position. The correction amount calculation unit that calculates the correction amount for correction, the correction unit that corrects the propagation time calculated by the time calculation unit based on the correction amount calculated by the correction amount calculation unit, and the mobile station and a determining intrusion judging unit whether invaded shielded area, the distance calculation unit, based on the propagation time in which the correction unit is corrected to calculate the propagation distance, the correction amount calculation unit, the When the mobile station is stopped at the predetermined position, the position calculated by the position calculation unit calculates a correction amount indicating the predetermined position, and the position calculation unit calculates the correction amount indicating the predetermined position, and the position calculation unit uses the intrusion determination unit to calculate the correction amount of the mobile station. When it is determined that the mobile station has entered the shielded area, the position of the mobile station is calculated based on the traveling direction and the moving speed of the mobile station .
In the present invention, radio signals transmitted from a plurality of fixed stations fixed at predetermined indoor positions are received. For the received radio signal, the propagation distance from the source to the receiving unit is calculated. The position of the own station is calculated based on the propagation distances of a plurality of radio signals whose sources are different from each other.
Since a radio signal having a high carrier wave is received from a plurality of fixed stations, there is a high probability that the radio signal traveling straight from the source will be received. As a result, the probability that an incorrect position is calculated as the position of the own station is low.
In addition, the propagation time of the radio signal is calculated. A correction amount for correcting the calculated propagation time is calculated, the calculated propagation time is corrected based on this correction amount, and an accurate propagation distance of the radio signal is calculated based on the corrected propagation time.
Calculates the correction amount at which the calculated position indicates a predetermined position when the own station is stopped at a predetermined position.
A reflector is installed in the room. The reflector reflects the radio signal towards the shielded area between the two shields. When it is determined that the mobile station has entered the shielded area, the position of the mobile station is calculated based on the traveling direction and moving speed of the mobile station.

According to the present invention, the probability that an erroneous position is calculated is low.

It is a block diagram which shows the main part structure of the positioning system in Embodiment 1. FIG. It is a block diagram which shows the main part composition of a fixed station. It is explanatory drawing of the method of generating a radio signal. It is a block diagram which shows the main part composition of a mobile station. It is explanatory drawing of decoding to the baseband signal. It is a flowchart which shows the procedure of the process which a calculation part executes. It is a chart which shows the correlation value and propagation distance associated with the source. It is a block diagram which shows the composition of the main part of the mobile station in Embodiment 2. FIG. It is a flowchart which shows the procedure of the process which a calculation part executes. It is a flowchart which shows the procedure of the process which a calculation part executes. It is a block diagram which shows the main part structure of the positioning system in Embodiment 3. FIG. It is a block diagram which shows the main part structure of the positioning system in Embodiment 4. It is a block diagram which shows the main part composition of a mobile station. It is a flowchart which shows the procedure of the process which a calculation part executes. It is a flowchart which shows the procedure of the process which a calculation part executes.

Hereinafter, the present invention will be described in detail with reference to the drawings showing the embodiments thereof.
(Embodiment 1)
FIG. 1 is a block diagram showing a configuration of a main part of the positioning system 1 according to the first embodiment. The positioning system 1 is provided in the room R and includes three fixed stations 10a, 10b, 10c, a control device 11, a mobile station 12, and a transfer device 13. The fixed stations 10a, 10b, and 10c are each fixed at a predetermined position of the room R. The positions of the fixed stations 10a, 10b, and 10c are the corners of the room R and are different from each other. The fixed stations 10a, 10b, and 10c are connected to the control device 11 by wire.

The mobile station 12 is mounted on the transport device 13. The transport device 13 transports a work such as a welded part, an electronic part, a substrate or a wafer, for example. The transport device 13 is, for example, an automatic guided vehicle that moves on a predetermined route, or a mobile body such as a mobile shuttle that moves on a track installed on the ceiling or floor. The operation of the transport device 13 is managed by a production control system called a MES (Manufacturing Execute System). In the room R, shields O1, O2, and O3 that shield the radio signal are present. The transport device 13 moves in the room R while avoiding contact with the shields O1, O2, and O3. The mobile station 12 moves in the room R together with the transfer device 13.

The fixed stations 10a, 10b, and 10c each transmit a radio signal to the mobile station 12 according to the instruction of the control device 11. The mobile station 12 calculates the position of its own station based on the radio signals received from the fixed stations 10a, 10b, and 10c, and outputs a position signal including position information indicating the calculated position to the carrier device 13. The transport device 13 changes the traveling direction, stops the movement, changes the moving speed, and the like based on the position information included in the position signal input from the mobile station 12.

FIG. 2 is a block diagram showing a main configuration of the fixed station 10a. The fixed station 10a includes a signal output unit 20, a clock unit 21, a coding unit 22, a code signal generator 23, a superimposition unit 24, a carrier wave generator 25, an amplifier 26, and a transmitting antenna 27.

The signal output unit 20 acquires time information indicating the current time from the clock unit 21. When the signal output unit 20 acquires the time information from the clock unit 21, the time indicated by the time information acquired by the signal output unit 20 coincides with or substantially coincides with the time at the time of acquisition. Further, a radio signal transmission instruction is input from the control device 11 to the signal output unit 20. The signal output unit 20 acquires time information from the clock unit 21 when a transmission instruction is input. The signal output unit 20 outputs a baseband signal including time information acquired from the clock unit 21, source information indicating the fixed station 10a, coordinate information indicating the position of the fixed station 10a in coordinates, and the like to the coding unit 22. To do. A stop instruction for instructing the stop of transmission of the wireless signal is input to the signal output unit 20. The signal output unit 20 stops the output of the baseband signal when the stop instruction is input.
The time information included in the baseband signal is transmission time information indicating the transmission time. In the following, the time information included in the baseband signal will be referred to as transmission time information.

The code signal generator 23 outputs a transmission side code signal corresponding to a predetermined code to the coding unit 22.
The coding unit 22 encodes the baseband signal by spreading the spectrum of the baseband signal input from the signal output unit 20 by using the transmitting side code signal input from the code signal generator 23. .. The coding unit 22 outputs the coded coded signal to the superimposing unit 24.

The carrier wave generator 25 outputs the carrier wave to the superimposing unit 24. The carrier wave output by the carrier wave generator 25 is a high frequency wave, for example, millimeter wave. The frequency range of millimeter waves is 30 GHz to 300 GHz.
The superimposition unit 24 generates a superimposition signal by superimposing the coded signal input from the coding unit 22 on the carrier wave input from the carrier wave generator 25. The superimposition unit 24 outputs the generated superimposition signal to the amplifier 26.

The amplifier 26 amplifies the amplitude of the superposed signal input from the superimposing unit 24, and outputs the superposed signal with the amplified amplitude to the transmitting antenna 27. The transmitting antenna 27 transmits the superimposed signal input from the amplifier 26 to the mobile station 12 as a radio signal.
Therefore, the superimposing unit 24 functions as a generating unit that generates a radio signal transmitted by the transmitting antenna 27, and the transmitting antenna 27 functions as a transmitting unit.

The transmitting antenna 27 has directivity, and as shown in FIG. 1, transmits the radio signal A1 in the first direction, transmits the radio signal A2 in the second direction, and transmits the radio signal A3 in the third direction. .. The transmitting antenna 27 switches the transmitting direction of the radio signal between the first direction, the second direction, and the third direction each time a predetermined time elapses. The transmission direction of the transmission antenna 27 is switched in the order of the first direction, the second direction, and the third direction.
The transmission direction may be switched based on the time indicated by the clock unit 21, a timer (not shown), or an instruction of the control device 11.

When a transmission instruction is input from the control device 11, the signal output unit 20 continuously outputs a baseband signal to the coding unit 22. At this time, the signal output unit 20 outputs the baseband signal to the coding unit 22 each time a predetermined time elapses. Therefore, the transmitting antenna 27 continuously transmits the radio signal, and the transmitting directions of the three radio signals continuously transmitted by the transmitting antenna 27 are different from each other.

FIG. 3 is an explanatory diagram of a method for generating a radio signal. FIG. 3 shows an example of waveforms of a baseband signal, a transmitting side code signal, a coded signal, a carrier wave, and a radio signal. Voltage and time are shown on each of these vertical and horizontal axes. For the sake of brevity, it is assumed that the baseband signal, the transmitting side coded signal, and the coded signal are digital signals indicating "+1" or "-1", respectively. In reality, "+1" corresponds to "(amplitude) / 2" and "-1" corresponds to "-(amplitude) / 2".

As described above, the signal output unit 20 outputs a baseband signal including transmission time information, transmission source information, and coordinate information to the coding unit 22. The baseband signal is an NRZ (Non-Return to Zero) signal. As described above, the code signal generator 23 outputs the transmission side code signal to the coding unit 22. The transmitting side code signal is a signal in which a predetermined waveform determined based on the code is periodically repeated. The period T of the transmission-side code signal matches or substantially matches the length of one bit of the baseband signal.

The coding unit 22 encodes the baseband signal by multiplying the baseband signal and the transmitting side code signal. Therefore, the waveform of the encoded signal during the period when the baseband signal indicates "+1" matches the predetermined waveform, and the waveform of the encoded signal during the period when the baseband signal indicates "-1" is positive or negative of the predetermined waveform. Matches the inverted waveform.

The minimum value of the pulse width of the coded signal is smaller than the minimum value of the pulse width of the baseband signal, that is, the period of one bit of the baseband signal. For binary signals, the spectral width is inversely proportional to the minimum pulse width. Therefore, the spectrum of the baseband signal is diffused by the coding unit 22 performing the coding. In the example of FIG. 3, the minimum value of the pulse width of the coded signal is (minimum value of the pulse width of the baseband signal) / 7. Therefore, the spectral width of the coded signal is 7 times the spectral width of the baseband signal.

The carrier wave output by the carrier wave generator 25 is a sine wave as shown in FIG. When the carrier wave is millimeter wave, the frequency of the carrier wave is one frequency in 30 GHz to 300 GHz.

As described above, the superimposition unit 24 generates a superimposition signal transmitted as a radio signal from the transmission antenna 27 by superimposing the coded signal output by the coding unit 22 on the carrier wave output by the carrier wave generator 25. To do. The waveform of the superimposed signal during the period when the coded signal indicates "+1" matches the waveform of the carrier wave, and the waveform of the superimposed signal during the period when the coded signal indicates "-1" is a waveform obtained by inverting the positive and negative of the waveform of the carrier wave. Matches.
As described above, the amplitude of the superposed signal generated by the superimposing unit 24 is amplified by the amplifier 26, and the superposed signal whose amplitude is amplified is transmitted from the transmitting antenna 27 as a radio signal.

The fixed stations 10b and 10c are configured in the same manner as the fixed stations 10a. In the description of the configuration of the fixed station 10a, the configuration of the fixed station 10b can be described by replacing each of the radio signals A1, A2, and A3 with the radio signals B1, B2, and B3. Similarly, in the description of the configuration of the fixed station 10a, the configuration of the fixed station 10c can be described by replacing each of the radio signals A1, A2, A3 with the radio signals C1, C2, C3.

The frequencies of the carrier waves output by the carrier wave generators 25 of the fixed stations 10a, 10b, and 10c are the same or substantially the same. Further, the codes used in the code signal generators 23 of the fixed stations 10a, 10b, and 10c are the same. Further, the times indicated by the clock units 21 of the fixed stations 10a, 10b, and 10c are the same or substantially the same. The control device 11 repeatedly adjusts these times so that the times indicated by the clock units 21 of the fixed stations 10a, 10b, and 10c match.

The control device 11 gives a transmission instruction to the fixed stations 10a, 10b, 10c so that at least two transmitting antennas 27 in the three fixed stations 10a, 10b, 10c do not transmit radio signals in the same time zone. The transmitting antenna 27 that outputs and transmits the wireless signal is changed over time. Therefore, at all times of the day, only one fixed station among the fixed stations 10a, 10b, 10c is transmitting the radio signal, or all of the fixed stations 10a, 10b, 10c are transmitting the radio signal. Is stopped.

The transmitting antennas 27 of the three fixed stations 10a, 10b, and 10c transmit radio signals as follows, for example.
First, the control device 11 outputs a transmission instruction to the signal output unit 20 of the fixed station 10a, and changes the transmitting antenna for transmitting the radio signal to the transmitting antenna 27 of the fixed station 10a. The transmitting antenna 27 of the fixed station 10a transmits the radio signals A1, A2, and A3 in this order.

After the radio signal A3 is transmitted, the control device 11 outputs a stop instruction to the signal output unit 20 of the fixed station 10a. After that, the control device 11 outputs a transmission instruction to the signal output unit 20 of the fixed station 10b, and changes the transmitting antenna for transmitting the radio signal to the transmitting antenna 27 of the fixed station 10b. The transmitting antenna 27 of the fixed station 10b transmits the radio signals B1, B2, and B3 in this order.
After the radio signal B3 is transmitted, the control device 11 outputs a stop instruction to the signal output unit 20 of the fixed station 10b. After that, the control device 11 outputs a transmission instruction to the signal output unit 20 of the fixed station 10c, and changes the transmitting antenna for transmitting the radio signal to the transmitting antenna 27 of the fixed station 10c. The transmitting antenna 27 of the fixed station 10c transmits the radio signals C1, C2, and C3 in this order.
After the radio signal C3 is transmitted, the control device 11 outputs a stop instruction to the signal output unit 20 of the fixed station 10c. After that, the control device 11 outputs the transmission instruction again to the signal output unit 20 of the fixed station 10a.

The signal output units 20 of the fixed stations 10a, 10b, and 10c each stop the output of the baseband signal when three times the predetermined time described above has elapsed after the transmission instruction is input from the control device 11. It may be configured as follows. In this case, the control device 11 may output a transmission instruction each time three times the predetermined time elapses. At this time, the control device 11 outputs transmission instructions in the order of the signal output units 20 of the fixed stations 10a, 10b, and 10c.

FIG. 4 is a block diagram showing a main configuration of the mobile station 12. The mobile station 12 includes a receiving antenna 30, an amplifier 31, a mixer 32, an oscillator 33, a low-pass filter (hereinafter referred to as LPF) 34, a decoding unit 35, a receiving detection unit 36, a code signal generator 37, an arithmetic unit 38, and a clock unit. It has 39, a timer 40, an output unit 41, and a storage unit 42.

The receiving antenna 30 receives the radio signal transmitted by the transmitting antenna 27 of the fixed stations 10a, 10b, and 10c, and outputs the received radio signal to the amplifier 31. The reception band of the radio signal of the reception antenna 30 is a part or all of a high frequency band, for example, a frequency band corresponding to millimeter waves (30 GHz to 300 GHz). The receiving antenna 30 functions as a receiving unit.
The amplifier 31 amplifies the amplitude of the radio signal received from the receiving antenna 30, and outputs the amplified radio signal to the mixer 32.
The oscillator 33 outputs a sine wave to the mixer 32.

The mixer 32 generates a mixed signal including a coded signal by mixing the radio signal input from the amplifier 31 and the sine wave output from the oscillator 33. The frequency of the sine wave output by the oscillator 33 is, for example, the same as the frequency of the carrier wave output by the carrier wave generator 25 of the fixed stations 10a, 10b, 10c. The mixer 32 outputs the generated mixing signal to the LPF 34.
The LPF 34 extracts a coded signal from the mixed signal input from the mixer 32, and outputs the extracted coded signal to the decoding unit 35 and the reception detection unit 36. The mixer 32 and LPF 34 function as an extractor.

The code signal generator 37 outputs a receiving side code signal corresponding to a predetermined code to the decoding unit 35. The code used in the code signal generator 37 is the same as the code used in the code signal generator 23 of the fixed stations 10a, 10b, 10c. Like the transmitting side code signal, the receiving side code signal is a signal in which a predetermined waveform determined based on the code is periodically repeated. The predetermined waveform and period are the same for each of the receiving side code signal and the transmitting side code signal.
The code used in the code signal generators 23 and 37 is, for example, a PN (Pseudo Noise) code.

The decoding unit 35 multiplies the receiving side code signal and the coded signal in a state where the receiving side code signal input from the code signal generator 37 and the coded signal input from the LPF 34 are in phase with each other. Thereby, the spectrum of the coded signal input from the LPF34 is despread. As a result, the coded signal extracted by the LPF 34 is decoded into a baseband signal.

FIG. 5 is an explanatory diagram of decoding to a baseband signal. In the following, the signal obtained by multiplying the receiving side code signal and the coded signal will be referred to as a multiplication signal. FIG. 5 shows an example of waveforms of the coded signal, the receiving side coded signal, and the multiplication signal. Voltage and time are shown on each of these vertical and horizontal axes. For the sake of simplicity, it is assumed that the receiving side code signal, the receiving side code signal, and the multiplication signal are digital signals indicating "+1" or "-1", respectively. In reality, "+1" corresponds to "(amplitude) / 2" and "-1" corresponds to "-(amplitude) / 2".

The decoding unit 35 multiplies the coded signal and the receiving side coded signal. Therefore, the multiplication signal indicates "+1" while the encoded signal and the receiving side encoded signal both indicate "+1" or "-1". Further, among the coded signal and the receiving side coded signal, one of them shows "+1" and the other shows "-1", and the multiplication signal shows "-1".

As shown in FIG. 5, when the phase difference between the coded signal and the receiving side coded signal is not zero, the multiplication signal does not match the baseband signal. At this time, the absolute value of the integrated value calculated by integrating over the period T of the receiving side code signal, that is, the correlation value is small. In the example of FIG. 5, the correlation value is 1.
When the phase difference between the coded signal and the receiving side code is zero, the multiplication signal matches the baseband signal and the correlation value is maximum. In the example of FIG. 5, the maximum value of the correlation value coincides with the length of the period T.

The decoding unit 35 adjusts the phase difference between the coded signal and the receiving side code to zero while monitoring the correlation value. When the correlation value is maximum, the phase difference is zero. As described above, the minimum value of the pulse width of the coded signal is smaller than the minimum value of the pulse width of the baseband signal, and the spectrum width is inversely proportional to the minimum value of the pulse width. Therefore, when the decoding unit 35 performs decoding, the spectrum of the coded signal is despread. In the example of FIG. 5, since the minimum value of the pulse width of the baseband signal is 7 times the minimum value of the pulse width of the coded signal, the spectrum width of the baseband signal is (spectral width of the coded signal) /. 7.

The correlation value increases as the reception strength of the radio signal received by the receiving antenna 30 increases. The decoding unit 35 outputs the decoded baseband signal and the correlation value information indicating the correlation value when the phase difference is zero to the calculation unit 38.
When the code used by the code signal generators 23 of the fixed stations 10a, 10b, and 10c is different from the code used by the code signal generator 37 of the mobile station 12, the correlation value is small regardless of the position difference, and the coded signal. Is not decoded into a baseband signal.

When the coded signal is input from the LPF 34, the reception detection unit 36 shown in FIG. 4 detects the reception of the radio signal and notifies the calculation unit 38 that the reception antenna 30 has received the radio signal.

The calculation unit 38 acquires time information indicating the current time from the clock unit 39. When the calculation unit 38 acquires the time information from the clock unit 39, the time indicated by the time information acquired by the calculation unit 38 substantially coincides with the time at the time of acquisition.
The timer 40 starts and ends timing according to the instruction of the calculation unit 38. The time counting time measured by the timer 40 is read out by the calculation unit 38.

The output unit 41 outputs a position signal including position information indicating the position of the mobile station 12 to the transfer device 13 according to the instruction of the calculation unit 38. As described above, the transport device 13 changes the traveling direction, stops the movement, changes the moving speed, and the like based on the position information included in the position signal input from the output unit 41.

The storage unit 42 is, for example, a non-volatile memory. The control program is stored in the storage unit 42. The calculation unit 38 has a CPU (Central Processing Unit) (not shown), and executes a control program to execute a process including a position calculation process for calculating the position of the mobile station 12.
Various data are stored in the storage unit 42 by the calculation unit 38. Further, the data stored in the storage unit 42 is read out by the calculation unit 38. Information indicating the positions of the fixed stations 10a, 10b, and 10c is stored in the storage unit 42.

FIG. 6 is a flowchart showing a procedure of processing executed by the calculation unit 38. First, the calculation unit 38 instructs the timer 40 to start timing (step S1), and determines whether or not the reception detection unit 36 has detected the reception of the radio signal (step S2).

When the calculation unit 38 determines that the reception detection unit 36 has detected the reception of the radio signal (S2: YES), the calculation unit 38 together with the transmission time information and the transmission source information included in the baseband signal input from the decoding unit 35. , Acquires the correlation value information input from the decoding unit 35 (step S3). Next, the calculation unit 38 acquires time information from the clock unit 39 (step S4). Here, the time indicated by the time information acquired by the calculation unit 38 is the reception time of the radio signal.

Next, the calculation unit 38 transmits the radio signal received by the receiving antenna 30 based on the transmission time indicated by the transmission time information acquired in step S3 and the reception time indicated by the time information acquired in step S4. The propagation time from the mobile station 12 to the receiving antenna 30 of the mobile station 12 is calculated (step S5). The calculation unit 38 calculates, for example, the period from the transmission time to the reception time as the propagation time. The calculation unit 38 functions as a time calculation unit.

Next, the calculation unit 38 calculates the propagation distance of the radio signal received by the receiving antenna 30 from the transmission source to the receiving antenna 30 of the mobile station 12 based on the propagation time calculated in step S5 (). Step S6). For example, when it is considered that the room is in a vacuum, the calculation unit 38 calculates the propagation distance by multiplying the propagation time by the propagation speed of the radio signal in the vacuum. The propagation speed of a radio signal in a vacuum is represented by the product of 3 and 10 to the 8th power (unit: m / s). The calculation unit 38 also functions as a distance calculation unit.

Next, the calculation unit 38 stores the correlation value indicated by the correlation information acquired in step S3 and the propagation distance calculated in step S6 in association with the source indicated by the source information acquired in step S3. (Step S7).
FIG. 7 is a chart showing the correlation value and the propagation distance associated with the transmission source. In step S7, for example, as shown in FIG. 7, the calculation unit 38 stores the correlation value Ma1 and the propagation distance La1 in association with the fixed station 10a which is the transmission source.

When the calculation unit 38 determines that the reception detection unit 36 has not detected the reception of the radio signal (S2: NO), or after executing step S7, the time counting time measured by the timer 40 is the reference time. It is determined whether or not it is the above (step S8). When the calculation unit 38 determines that the time counting time is less than the reference time (S8: NO), the calculation unit 38 executes step S2.

The calculation unit 38 stores the correlation value and the propagation time of the radio signal received by the receiving antenna 30 in association with the transmission source until the time counting time becomes equal to or longer than the reference time. As described above, the radio signals A1, A2, A3, B1, B2, B3, C1, C2, and C3 are sequentially transmitted from the fixed stations 10a, 10b, and 10c each time a predetermined time elapses. The reference time is set to, for example, 9 times a predetermined time. As a result, the receiving antenna 30 of the mobile station 12 can receive all of the radio signals A1, A2, A3, B1, B2, B3, C1, C2, and C3 before the time counting time exceeds the reference time. Is.

When all of the radio signals A1, A2, A3, B1, B2, B3, C1, C2, and C3 are received before the time counting time exceeds the reference time, they are associated with the source as shown in FIG. Nine correlation values and nine propagation distances are stored in the storage unit 42. If, for example, the radio signal B3 does not reach the receiving antenna 30 of the mobile station 12 by the time when the timekeeping time exceeds the reference time, eight correlation values and eight propagation distances are associated with the source. Is stored in the storage unit 42.

When the calculation unit 38 determines that the time counting time is equal to or longer than the reference time (S8: YES), the calculation unit 38 instructs the timer 40 to end the time counting (step S9), and correlates values for each of the fixed stations 10a, 10b, and 10c. Selects the maximum propagation distance (step S10). The calculation unit 38 executes step S10 based on the correlation value and the propagation distance stored in the storage unit 42 until the time counting time becomes equal to or longer than the reference time. For each of the fixed stations 10a, 10b, and 10c, the higher the correlation value, the better the reception state of the radio signal. Therefore, the propagation distance having the maximum correlation value is selected.

For example, it is assumed that the correlation value and the propagation distance are stored in the storage unit 42 by the time the timekeeping time becomes equal to or longer than the reference time, as shown in FIG. The calculation unit 38 selects the propagation distance corresponding to the maximum correlation value among the correlation values Ma1, Ma2, and Ma3 for the fixed station 10a. When the correlation value Ma1 is the maximum correlation value, the propagation distance La1 is selected. Similarly, the calculation unit 38 selects the propagation distance corresponding to the maximum correlation value in the correlation values Mb1, Mb2, Mb3 for the fixed station 10b, and the maximum among the correlation values Mc1, Mc2, Mc3 for the fixed station 10c. Select the propagation distance corresponding to the correlation value of.

Next, the calculation unit 38 calculates the position of the mobile station 12 based on the three propagation distances selected in step S10 (step S11). The calculation unit 38 calculates the position of the mobile station 12 by, for example, hyperbolic navigation. It is assumed that the calculation unit 38 selects the propagation distances La1, Lb1, Lc1 corresponding to the fixed stations 10a, 10b, and 10c in step S10, respectively. In hyperbolic navigation, the calculation unit 38 indicates the position where the difference in distance between the fixed stations 10a, 10b and 10b is the absolute value of (La1-Lb1) at the coordinates indicating the positions of the fixed stations 10a, 10b and 10c. Draw a hyperbola, draw a second hyperbola showing the position where the difference in distance between the fixed stations 10b and 10c is the absolute value of (Lb1-Lc1), and set the intersection of the first and second hyperbolas to the position of the mobile station 12. Calculate as. The first hyperbola is a hyperbola whose two focal points are the positions of the fixed stations 10a and 10b. The second hyperbola is a hyperbola whose two focal points are the positions of the fixed stations 10b and 10c. The positions of the fixed stations 10a, 10b, and 10c are the positions indicated by the coordinate information included in the baseband signal of the radio signal whose source is the fixed stations 10a, 10b, and 10c.

The calculation unit 38 may calculate the position of the mobile station 12 by another method. For example, the calculation unit 38 draws a circle in which the center is the position of the fixed station 10a and the radius is the propagation distance La1 at the coordinates indicating the positions of the fixed stations 10a, 10b, 10c, and the center is the position of the fixed station 10b. Draw a circle whose radius is the propagation distance Lb1 and whose center is the position of the fixed station 10c and whose radius is the propagation distance Lc1. Then, the calculation unit 38 may calculate the intersection of the three circles as the position of the mobile station 12.
The calculation unit 38 also functions as a position calculation unit.

Next, the calculation unit 38 instructs the output unit 41 to output the position signal including the position information indicating the position calculated in step S11 to the transfer device 13 (step S12).
After executing step S12, the calculation unit 38 ends the process. After completing the process, the calculation unit 38 executes step S1 again and repeats the calculation of the position of the mobile station 12.

In the positioning system 1 configured as described above, since the transmitting antennas 27 of the fixed stations 10a, 10b, and 10c each have directivity, the receiving antennas of the mobile station 12 are reflected by an object such as a wall surface or a shelf in the room. The number of radio signals reaching 30 is small. Further, the carrier wave of the radio signal transmitted by the transmitting antennas 27 of the fixed stations 10a, 10b, and 10c is a high frequency, for example, millimeter wave. Therefore, the radio signal does not spread significantly due to diffraction, and the radio signal transmitted from the transmitting antennas 27 of the fixed stations 10a, 10b, and 10c has a high probability of reaching the receiving antenna 30 of the mobile station 12 in a straight line. .. As a result, the calculation unit 38 of the mobile station 12 has a low probability of calculating an erroneous position as the position of the mobile station 12.

Further, at least two transmitting antennas 27 in the fixed stations 10a, 10b, 10c do not transmit the radio signal in the same time zone, and the radio signal is transmitted in the transmitting antenna 27 of the fixed stations 10a, 10b, 10c. The transmitting antenna 27 to transmit is changed over time. Therefore, the plurality of radio signals do not interfere with each other, and the transmission time information, the transmission source information, and the like included in the radio signals are appropriately acquired by the calculation unit 38 of the mobile station 12.

Further, the transmission antennas 27 of the fixed stations 10a, 10b, and 10c each continuously transmit radio signals. At this time, the transmitting antenna 27 changes the transmitting direction of the radio signal each time a predetermined time elapses. Therefore, there is a high probability that the radio signal transmitted by the transmitting antennas 27 of the fixed stations 10a, 10b, and 10c will be received by the receiving antenna 30 of the mobile station 12.

Further, in the mobile station 12 configured as described above, the receiving antenna 30 receives a radio signal having a high frequency carrier wave. Therefore, the receiving antenna 30 has a high probability of receiving a radio signal traveling straight from the source. As a result, the probability that the calculation unit 38 calculates an erroneous position as the position of the mobile station 12 is low.

(Embodiment 2)
FIG. 8 is a block diagram showing a main configuration of the mobile station 12 according to the second embodiment.
Hereinafter, the difference between the second embodiment and the first embodiment will be described. Since the other configurations other than the configurations described later are common to the first embodiment, the same reference numerals as those of the first embodiment are assigned to the components common to the first embodiment, and the description thereof is omitted. To do.

In the positioning system 1 according to the second embodiment, the configurations of the mobile station 12 and the transport device 13 are different from those of the positioning system 1 according to the first embodiment.
The transport device 13 in the second embodiment operates in the same manner as in the first embodiment. The transport device 13 further stops at a predetermined position, for example, a position near the entrance of the room R. While the transfer device 13 is stopped at a predetermined position, the transfer device 13 continues to output a stop signal indicating that the device 13 is stopped at the predetermined position to the mobile station 12. As described in the description of the first embodiment, the mobile station 12 is mounted on the transfer device 13. Therefore, when the transport device 13 is stopped at a predetermined position, the mobile station 12 is also stopped at a predetermined position.

The mobile station 12 in the second embodiment has an input unit 43 in addition to the constituent parts of the mobile station 12 in the first embodiment. A stop signal is input to the input unit 43 from the transport device 13. When the stop signal is input from the transport device 13, the input unit 43 notifies the calculation unit 38 to that effect.

In the positioning system 1, the time indicated by the clock units 21 of the fixed stations 10a, 10b, and 10c may not match the time indicated by the clock unit 39 of the mobile station 12. When the times indicated by the clock units 21 and 39 are different from each other, an error occurs in the propagation time calculated by the calculation unit 38. Therefore, the storage unit 42 stores the correction amount information indicating the correction amount for correcting the propagation time calculated by the calculation unit 38.

The calculation unit 38 calculates the correction amount and changes the correction amount indicated by the correction amount information. The calculation unit 38 also functions as a correction amount calculation unit. Further, the value of the correction flag is stored in the storage unit 42. The value of the correction flag is zero or one. When the value of the correction flag is zero, it means that the correction amount is not calculated. When the value of the correction flag is 1, it means that the correction amount is calculated. The value of the correction flag is also changed by the calculation unit 38.

9 and 10 are flowcharts showing a procedure of processing executed by the calculation unit 38. The calculation unit 38 repeatedly executes this process.
Steps S25 to S29, S31 to S35, S39, and S40 executed by the calculation unit 38 in the second embodiment are the steps S1 to S5, S6 to S10, S11, and S12 executed by the calculation unit 38 in the first embodiment, respectively. The same is true. Therefore, detailed description of steps S25 to S29, S31 to S35, S39, and S40 will be omitted.

The calculation unit 38 determines whether or not the mobile station 12 has stopped at a predetermined position (step S21). In step S21, the calculation unit 38 determines that the mobile station 12 has stopped at a predetermined position when the stop signal is input to the input unit 43, and moves when the stop signal is not input to the input unit 43. It is determined that the station 12 has not stopped at a predetermined position. The calculation unit 38 also functions as a determination unit.

When the calculation unit 38 determines that the mobile station 12 has not stopped at a predetermined position (S21: NO), the calculation unit 38 sets the value of the correction flag to zero (step S22). When the calculation unit 38 determines that the mobile station 12 has stopped at a predetermined position (S21: YES), the calculation unit 38 changes the correction amount indicated by the correction amount information to zero (step S23), and sets the value of the correction flag to 1. (Step S24). After executing step S22 or step S24, the calculation unit 38 executes step S25.

After executing step S29, the calculation unit 38 corrects the propagation time calculated in step S29 based on the correction amount indicated by the correction amount information (step S30). For example, the calculation unit 38 corrects by adding a correction amount which is a positive or negative value to the propagation time calculated in step S29. The calculation unit 38 also functions as a correction unit.
The calculation unit 38 executes step S31 after executing step S30. In step S31, the calculation unit 38 calculates the propagation distance based on the propagation time corrected in step S30. The calculation unit 38 calculates the propagation distance by, for example, multiplying the propagation time corrected in step S30 by the propagation speed of the radio signal.

When the calculation unit 38 calculates the correction amount, that is, when the value of the correction flag is 1, the correction amount indicated by the correction information is zero, so that the propagation time is not corrected in step S30.

After executing step S35, the calculation unit 38 determines whether or not the value of the correction flag is 1 (step S36). When the calculation unit 38 determines that the value of the correction flag is 1 (S36: YES), the calculation unit 38 calculates the correction amount (step S37).

In one example, the storage unit 42 stores the propagation time of the radio signal from the transmitting antennas 27 of the fixed stations 10a, 10b, and 10c to the receiving antenna 30 of the mobile station 12 stopped at a predetermined position. ing. For each of the fixed stations 10a, 10b, and 10c, the correction amount is calculated from the difference between the propagation time corresponding to the propagation distance having the maximum correlation value and the propagation time stored in the storage unit 42.
In another example, the three propagation distances selected in step S35 are increased or decreased by the same distance so that the calculation result indicates a predetermined position, and the correction amount is calculated from the propagation time corresponding to the change amount of the distance. ..

After executing step S37, the calculation unit 38 changes the correction amount indicated by the correction amount information to the correction amount calculated in step S37 (step S38).
When the calculation unit 38 determines that the value of the correction flag is not 1, that is, the value of the correction flag is zero (S36: NO), the calculation unit 38 executes step S39.

After executing step S38 or step S40, the calculation unit 38 ends the process. After completing the process, the calculation unit 38 executes step S21 again and repeats the calculation of the position of the mobile station 12.
When the value of the correction flag is 1, it is obvious that the position of the mobile station 12 is a predetermined position. Therefore, the calculation unit 38 does not need to calculate the position of the mobile station 12 and output the position signal indicating the position of the mobile station 12 after executing step S38.

In the positioning system 1 according to the second embodiment, the calculation unit 38 of the mobile station 12 calculates the accurate propagation distance of the radio signal based on the corrected propagation time. Further, the calculation unit 38 calculates the correction amount when it is determined that the mobile station 12 is stopped at a predetermined position. Therefore, an accurate correction amount is calculated.
The fixed stations 10a, 10b, 10c in the second embodiment are configured in the same manner as in the first embodiment, and the mobile station 12 in the second embodiment includes the same configuration as the mobile station 12 in the first embodiment. It has been. Therefore, the positioning system 1 and the mobile station 12 in the second embodiment have the same effects as those in the first embodiment.

(Embodiment 3)
FIG. 11 is a block diagram showing a configuration of a main part of the positioning system 1 according to the third embodiment.
Hereinafter, the differences between the third embodiment and the first embodiment will be described. Since the other configurations other than the configurations described later are common to the first embodiment, the same reference numerals as those of the first embodiment are assigned to the components common to the first embodiment, and the description thereof is omitted. To do.

The positioning system 1 according to the third embodiment includes a fixed station 10d in addition to the components included in the positioning system 1 according to the first embodiment. The fixed station 10d is also fixed at a predetermined position of the room R and is connected to the control device 11 by wire. The positions of the fixed stations 10a, 10b, 10c, and 10d are different from each other. The fixed station 10d also transmits a radio signal to the mobile station 12 according to the instruction of the control device 11. The mobile station 12 calculates the position of its own station based on the radio signals received from the fixed stations 10a, 10b, 10c, and 10d.

The fixed station 10d is configured in the same manner as the fixed station 10a. In the description of the configuration of the fixed station 10a in the first embodiment, the configuration of the fixed station 10d can be described by replacing each of the radio signals A1, A2, A3 with the radio signals D1, D2, D3.

The frequency of the carrier wave output by the carrier wave generator 25 of the fixed station 10d is the same as or substantially the same as the frequency output by the carrier wave generator 25 of each of the fixed stations 10a, 10b, and 10c. Further, the code used in the code signal generator 23 of the fixed station 10d is also the same as the code used in the code signal generator 23 of each of the fixed stations 10a, 10b, and 10c. The control device 11 repeatedly adjusts these times so that the clocks 21 of the fixed stations 10a, 10b, 10c, and 10d match the times.

Similar to the first embodiment, the control device 11 is fixed so that at least two transmitting antennas 27 among the four fixed stations 10a, 10b, 10c, and 10d do not transmit radio signals in the same time zone. A transmission instruction is output to stations 10a, 10b, 10c, and 10d, and the transmission antenna 27 that transmits a radio signal is changed over time. Therefore, at all times of the day, only one fixed station among the fixed stations 10a, 10b, 10c, 10d is transmitting the radio signal, or all of the fixed stations 10a, 10b, 10c, 10d are transmitting the radio signal. The transmission of wireless signals is stopped.
The receiving antenna 30 of the mobile station 12 receives the radio signal transmitted by the transmitting antenna 27 of the fixed stations 10a, 10b, 10c, 10d, and the received radio signal is output to the amplifier 31.

The calculation unit 38 of the mobile station 12 performs the same processing as in the first embodiment. The reference time is set to, for example, 12 times a predetermined time. As a result, by the time the time counting time measured by the timer 40 exceeds the reference time, the receiving antenna 30 of the mobile station 12 has the radio signals A1, A2, A3, B1, B2, B3, C1, C2, C3. It is possible to receive all of D1, D2, and D3.

In step S10, the calculation unit 38 selects the propagation distance having the maximum correlation value for each of the fixed stations 10a, 10b, 10c, and 10d. In step S11, the calculation unit 38 calculates the position of the mobile station 12 based on the four propagation times selected in step S10. Here, since the calculation unit 38 uses four propagation distances, it relates not only to the two-dimensional position, that is, the position related to the vertical and horizontal directions in FIG. The position can be calculated. The position related to the height is the position in the direction perpendicular to the paper surface of FIG.
The positioning system 1 and the mobile station 12 in the third embodiment have the same effects as those in the first embodiment.

In the third embodiment, when the position calculated by the calculation unit 38 is sufficient in a two-dimensional position, the calculation unit 38 has a correlation value for each of the three fixed stations 10a, 10b, 10c, and 10d. The maximum propagation distance may be selected and the position of the mobile station 12 may be calculated based on the three selected propagation distances. In this configuration, the receiving antenna 30 of the mobile station 12 cannot receive all the radio signals continuously transmitted by one transmitting antenna 27 in the fixed stations 10a, 10b, 10c, and 10d. However, the position of the mobile station 12 is calculated.

Further, the number of fixed stations may be K (K: an integer of 5 or more). When the position calculated by the calculation unit 38 is sufficient in the two-dimensional position, the calculation unit 38 selects and selects the propagation distance having the maximum correlation value for each of the three fixed stations. The position of the mobile station 12 may be calculated based on one propagation distance. In this configuration, when all the radio signals continuously transmitted by the transmitting antennas 27 of the (K-3) fixed stations among the K fixed stations are not received by the receiving antenna 30 of the mobile station 12. Even if there is, the position of the mobile station 12 is calculated.

When the position to be calculated by the calculation unit 38 is a three-dimensional position, the calculation unit 38 selects the propagation distance having the maximum correlation value for each of the four fixed stations, and the selected four. The position of the mobile station 12 may be calculated based on the propagation distance. In this configuration, the receiving antenna 30 of the mobile station 12 cannot receive all the radio signals continuously transmitted by the transmitting antennas 27 of the (K-4) fixed stations among the K fixed stations. Even in this case, the position of the mobile station 12 is calculated.
When the number of fixed stations is K, the reference time is set to, for example, 3.K times the predetermined time. "・" Represents a product.
Further, if the one-dimensional position is sufficient for the position calculated by the calculation unit 38, the number of fixed stations may be two. In this case, the reference time is set to, for example, 6 times a predetermined time.

Further, when the transfer device 13 is stopped at a predetermined position, the calculation unit 38 of the mobile station 12 adjusts the correction amount when the mobile station 12 is stopped at the predetermined position, as in the second embodiment. The calculated propagation time may be corrected based on the calculated correction amount.

(Embodiment 4)
FIG. 12 is a block diagram showing a main configuration of the positioning system 1 according to the fourth embodiment.
Hereinafter, the differences between the fourth embodiment and the first embodiment will be described. Since the other configurations other than the configurations described later are common to the first embodiment, the same reference numerals as those of the first embodiment are assigned to the components common to the first embodiment, and the description thereof is omitted. To do.

The positioning system 1 according to the fourth embodiment also includes the components included in the positioning system 1 according to the first embodiment. In the fourth embodiment, the environment of the indoor R is different from that of the first embodiment. In the fourth embodiment, the shields O4 and O5 are present instead of the shields O1, O2 and O3. The shields O4 and O5 are arranged so as to face each other. The transport device 13 can move in the area between the shields O4 and O5. Since the mobile station 12 is mounted on the transport device 13, there is a possibility that the mobile station 12 moves in the area between the shields O4 and O5.

When the mobile station 12 is located in the region between the shields O4 and O5, as shown in FIG. 12, the radio signal transmitted by the transmitting antenna 27 of the fixed stations 10b and 10c reaches the mobile station 12 directly. There is no such thing. In the following, the area between the shields O4 and O5 will be referred to as a shielded area.

In the positioning system 1 of the fourth embodiment, since the radio signal reaches the mobile station 12 located in the shielded area, the positioning system 1 of the fourth embodiment further includes a reflector 14 that reflects the radio signal. The reflector 14 has, for example, a triangular columnar shape. The reflector 14 reflects the radio signal transmitted by the transmitting antenna 27 of the fixed stations 10b and 10c. The radio signal reflected by the reflector 14 propagates in the shielded area. When the mobile station 12 is located in the shielded area, the receiving antenna 30 of the mobile station 12 receives the radio signal reflected by the reflector 14.

FIG. 13 is a block diagram showing a main configuration of the mobile station 12. The mobile station 12 in the fourth embodiment further includes a Doppler measuring instrument 44 in addition to the components of the mobile station 12 in the first embodiment. When the receiving antenna 30 of the mobile station 12 receives the radio signal while the mobile station 12 is moving, the carrier wave of the radio signal received by the receiving antenna 30 is the carrier wave of the radio signal at the time when the radio signal is transmitted. Is different. This phenomenon is the so-called Doppler effect.

When the traveling direction of the mobile station 12 is the same as the propagation direction of the radio signal, the frequency of the carrier wave of the radio signal received by the receiving antenna 30 is lower than the frequency of the carrier wave at the time of transmission, and the moving speed of the mobile station 12 The faster the difference between these frequencies.
Further, when the traveling direction of the mobile station 12 is opposite to the propagation direction of the radio signal, the frequency of the carrier wave of the radio signal received by the receiving antenna 30 is higher than the frequency of the carrier wave at the time of transmission, and the mobile station 12 moves. The faster the speed, the greater the difference between these frequencies.

From the above, when the mobile station 12 is located in the shielded area, the frequency of the carrier wave of the radio signal received by the receiving antenna 30 and the frequency of the carrier wave output by the carrier wave generator 25 of the fixed stations 10a, 10b, 10c. Based on the difference between the two, the traveling direction and the moving speed of the mobile station 12 can be detected.

The amplifier 31 amplifies the amplitude of the radio signal received from the receiving antenna 30, and outputs the amplified radio signal to the mixer 32 and the Doppler measuring instrument 44.

When the mobile station 12 is located in the shielded area, the Doppler measuring instrument 44 determines the carrier frequency of the radio signal input from the amplifier 31 and the carrier frequency of the radio signal input from the amplifier 31 for each of the radio signals transmitted by the transmitting antennas 27 of the fixed stations 10b and 10c. The traveling direction and traveling speed of the mobile station 12 are detected based on the difference from the frequency of the carrier wave output by the carrier wave generator 25. The frequency of the carrier wave output by the carrier wave generator 25 is stored in advance in the storage unit 42. The Doppler measuring instrument 44 notifies the calculation unit 38 of the detected traveling direction and moving speed. The Doppler measuring instrument 44 notifies the calculation unit 38 that it is approaching or moving away from the reflector 14 as the traveling direction.

14 and 15 are flowcharts showing a procedure of processing executed by the calculation unit 38. The calculation unit 38 repeatedly executes this process. The storage unit 42 stores the value of the shielding flag. The value of the shield flag is zero or one. When the value of the shielding flag is zero, it means that the mobile station 12 is not located in the shielding area. When the value of the shielding flag is 1, it means that the mobile station 12 is located in the shielding area. Further, the storage unit 42 stores a layout diagram showing the position of an object fixed in the room R.
Steps S51 to S60 executed by the calculation unit 38 in the third embodiment are the same as steps S1 to S10 executed by the calculation unit 38 in the first embodiment. Therefore, detailed description of steps S1 to S10 will be omitted.

After executing step S60, the calculation unit 38 stores the three propagation distances selected in step S60 in the storage unit 42 (step S61). One of the fixed stations 10a, 10b, and 10c is associated with each of these three propagation distances. As described above, the processes shown in FIGS. 14 and 15 are repeatedly executed. Therefore, the transition of the propagation distance is stored in the storage unit 42 for each of the fixed stations 10a, 10b, and 10c.

Next, the calculation unit 38 determines whether or not the value of the shielding flag is zero (step S62). When the calculation unit 38 determines that the value of the shielding flag is zero (S62: YES), the calculation unit 38 determines whether or not the mobile station 12 has invaded the shielding area (step S63). The propagation distance of the radio signal reflected by the reflector 14 and reaching the receiving antenna 30 of the mobile station 12 is longer than the propagation distance of the radio signal directly reaching the receiving antenna 30 of the mobile station 12 from the source. Therefore, when the mobile station 12 invades the shielded area, the propagation distance of the radio signal transmitted by the transmitting antennas 27 of the fixed stations 10b and 10c suddenly changes significantly. Therefore, for the radio signals transmitted by the transmitting antennas 27 of the fixed stations 10b and 10c, the propagation distance selected in this step S60 is longer than the propagation distance selected in the previous step S60, and the difference between these propagation distances. When is equal to or greater than a predetermined first reference distance, the calculation unit 38 determines that the mobile station 12 has invaded the shielded area. In other cases, the calculation unit 38 determines that the mobile station 12 has not invaded the shielded area.

When it is determined that the mobile station 12 has not invaded the shielded area (S63: NO), the calculation unit 38 moves in the same manner as in step S11 in the first embodiment based on the three propagation distances selected in step S60. The position of the station 12 is calculated (step S64).

When the calculation unit 38 determines that the mobile station 12 has invaded the shielded area (S63: YES), the calculation unit 38 sets the value of the shield flag to 1 (step S65). As described in the description of step S67, in the processes shown in FIGS. 14 and 15, the position of the mobile station 12 calculated by the calculation unit 38 is stored in the storage unit 42. Further, since the processes shown in FIGS. 14 and 15 are repeatedly executed, the transition of the position of the mobile station 12 calculated by the calculation unit 38 is stored in the storage unit 42.

After executing step S65, the calculation unit 38 calculates the position of the mobile station 12 based on the position of the mobile station 12 in the past, the notification result input from the Doppler measuring instrument 44, the layout drawing of the room R, and the like. (Step S66). The notification result input from the Doppler measuring instrument 44 is the traveling direction and traveling speed of the mobile station 12 described above.

After executing step S64 or step S66, the calculation unit 38 stores the calculated position of the mobile station 12 in the storage unit 42 (step S67). After that, the calculation unit 38 instructs the output unit 41 to output the position signal including the position information indicating the position calculated in step S64 or step S66 to the transfer device 13 (step S68).
After executing step S68, the calculation unit 38 ends the process. After completing the process, the calculation unit 38 executes step S1 again and repeats the calculation of the position of the mobile station 12.

When the calculation unit 38 determines that the value of the shielding flag is not zero, that is, the value of the shielding flag is 1 (S62: NO), the calculation unit 38 determines whether or not the mobile station 12 has left the shielding area ( Step S69). As described above, the propagation distance of the radio signal reflected by the reflector 14 and reaching the receiving antenna 30 of the mobile station 12 is larger than the propagation distance of the radio signal directly reaching the receiving antenna 30 of the mobile station 12 from the source. long. Therefore, when the mobile station 12 leaves the shielded area, the propagation distance of the radio signal transmitted by the transmitting antennas 27 of the fixed stations 10b and 10c suddenly changes significantly. Therefore, for the radio signals transmitted by the fixed stations 10b and 10c, the propagation distance selected in this step S60 is shorter than the propagation distance selected in the previous step S60, and the difference between these propagation distances is a predetermined thirst. When the distance is 2 reference distances or more, the calculation unit 38 determines that the mobile station 12 has left the shielded area. In other cases, the calculation unit 38 determines that the mobile station 12 has not left the shielded area.

When the calculation unit 38 determines that the mobile station 12 has not left the shielded area (S69: NO), the calculation unit 38 executes step S66, and subsequently, the position of the mobile station 12 in the past and the input from the Doppler measuring instrument 44 are input. The position of the mobile station 12 is calculated based on the notification result and the layout drawing of the room R.
When the calculation unit 38 determines that the mobile station 12 has left the shielded area (S69: YES), the calculation unit 38 sets the value of the shield flag to zero (step S70), and executes step S64. The calculation unit 38 returns the position calculation method to the calculation method performed based on the three propagation distances selected in step S60.

In the positioning system 1 according to the fourth embodiment, even when the mobile station 12 is located in the shielded area, the radio signal transmitted by the transmitting antenna 27 of the fixed stations 10a, 10b, 10c reaches the mobile station 12. .. Further, even when the mobile station 12 is located in the shielded area, the calculation unit 38 can calculate the position of the mobile station 12 based on the notification result notified by the Doppler measuring instrument 44.

The fixed stations 10a, 10b, 10c in the fourth embodiment are configured in the same manner as in the first embodiment, and the mobile station 12 in the fourth embodiment includes the same configuration as the mobile station 12 in the first embodiment. It has been. Therefore, the positioning system 1 and the mobile station 12 in the fourth embodiment have the same effects as those in the first embodiment.

When the transfer device 13 is stopped at a predetermined position, the calculation unit 38 of the mobile station 12 calculates the correction amount when the mobile station 12 is stopped at the predetermined position, as in the second embodiment. Then, the calculated propagation time may be corrected based on the calculated correction amount.
Further, in the fourth embodiment, the number of fixed stations may be M (M: an integer of 4 or more). The calculation unit 38 may select the propagation distance having the maximum correlation value for each of the three fixed stations, and calculate the position of the mobile station 12 based on the selected three propagation distances. .. In this configuration, when all the radio signals continuously transmitted by the transmitting antennas 27 of the (M-3) fixed stations among the M fixed stations are not received by the receiving antennas 30 of the mobile station 12. Even if there is, the position of the mobile station 12 is calculated.

In the first to fourth embodiments, the number of transmission directions of the radio signal transmitted by the transmission antenna 27 of the fixed station is not limited to 3, and may be 2 or 4 or more. Also, the number of transmission directions does not have to be the same for all fixed stations. Further, the transmission antenna 27 of the fixed station does not have to continuously transmit the radio signal. Further, the position of the fixed station may be any position of the indoor R that is different from each other, and is not limited to the corner of the indoor R.

Further, the method of calculating the propagation time is not limited to the calculation method based on the transmission time and the reception time of the radio signal. For example, the output of the transmitting side code signal performed by the code signal generator 23 of one fixed station and the output of the receiving side code signal performed by the code signal generator 37 of the mobile station 12 are performed at the same time in the mobile station 12. In, the phase difference between the coded signal and the receiving side coded signal (see FIG. 5) may be calculated as the propagation time.
Further, the correlation value indicated by the correlation value information output by the decoding unit 35 is not limited to the correlation value when the phase difference between the coded signal and the receiving side coded signal is zero, and is not limited to the correlation value of the coded signal and the receiving side coded signal. It may be a correlation value when the phase difference is not zero.

The disclosed embodiments 1 to 4 should be considered as exemplary in all respects and not restrictive. The scope of the present invention is indicated by the scope of claims, not the meaning described above, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

1 Positioning system 10a, 10b, 10c, 10d Fixed station 12 Mobile station 22 Coding unit 24 Superimposing unit (generating unit)
27 Transmitting antenna (transmitter)
30 Receiving antenna (receiver)
32 Mixer (part of extraction section)
34 LPF (part of extraction section)
35 Decoding unit 38 Calculation unit (distance calculation unit, position calculation unit, time calculation unit, correction amount calculation unit, correction unit, judgment unit)
R room

Claims (8)

With multiple fixed stations fixed at predetermined indoor positions,
And a mobile station moving within the chamber,
It is provided with a reflector that is present in the room and reflects the radio signal toward a shielded area between two shields that shield the radio signal.
Each of the plurality of fixed stations has a directivity and has a transmitter for transmitting a radio signal having a high frequency carrier wave.
The mobile station
A receiving unit that receives a radio signal transmitted by the transmitting unit of the plurality of fixed stations, and a receiving unit that receives the radio signal transmitted by the transmitting unit.
A distance calculation unit that calculates the propagation distance from the transmission source to the reception unit for the radio signal received by the reception unit, and a distance calculation unit.
A position calculation unit that calculates the position of the mobile station based on the propagation distances of a plurality of radio signals whose sources are different from each other, which is calculated by the distance calculation unit.
A time calculation unit that calculates the propagation time from the transmission source to the reception unit for the radio signal received by the reception unit, and a time calculation unit.
The time is calculated based on the propagation time of the radio signal propagated from the transmitting unit to the receiving unit of the fixed station when the mobile station is stopped at a predetermined position, and the propagation time stored in advance. A correction amount calculation unit that calculates a correction amount for correcting the propagation time calculated by the unit, and a correction amount calculation unit.
A correction unit that corrects the propagation time calculated by the time calculation unit based on the correction amount calculated by the correction amount calculation unit, and a correction unit that corrects the propagation time calculated by the time calculation unit .
It has an intrusion determination unit that determines whether or not the mobile station has invaded the shielded area.
The distance calculation unit calculates the propagation distance on the basis of a propagation time during which the correcting unit is corrected,
When the intrusion determination unit determines that the mobile station has invaded the shielded area, the position calculation unit calculates the position of the mobile station based on the traveling direction and moving speed of the mobile station. A featured positioning system. With multiple fixed stations fixed at predetermined indoor positions,
And a mobile station moving within the chamber,
It is provided with a reflector that is present in the room and reflects the radio signal toward a shielded area between two shields that shield the radio signal.
Each of the plurality of fixed stations has a directivity and has a transmitter for transmitting a radio signal having a high frequency carrier wave.
The mobile station
A receiving unit that receives a radio signal transmitted by the transmitting unit of the plurality of fixed stations, and a receiving unit that receives the radio signal transmitted by the transmitting unit.
A distance calculation unit that calculates the propagation distance from the transmission source to the reception unit for the radio signal received by the reception unit, and a distance calculation unit.
A position calculation unit that calculates the position of the mobile station based on the propagation distances of a plurality of radio signals whose sources are different from each other, which is calculated by the distance calculation unit.
A time calculation unit that calculates the propagation time from the transmission source to the reception unit for the radio signal received by the reception unit, and a time calculation unit.
When the mobile station is stopped at a predetermined position, a correction amount calculation unit that calculates a correction amount for correcting the propagation time calculated by the time calculation unit, and a correction amount calculation unit.
A correction unit that corrects the propagation time calculated by the time calculation unit based on the correction amount calculated by the correction amount calculation unit, and a correction unit that corrects the propagation time calculated by the time calculation unit .
It has an intrusion determination unit that determines whether or not the mobile station has invaded the shielded area.
The distance calculation unit calculates the propagation distance on the basis of a propagation time during which the correcting unit is corrected,
The correction amount calculation unit calculates a correction amount in which the position calculated by the position calculation unit indicates the predetermined position when the mobile station is stopped at the predetermined position.
When the intrusion determination unit determines that the mobile station has invaded the shielded area, the position calculation unit calculates the position of the mobile station based on the traveling direction and moving speed of the mobile station. A featured positioning system. The positioning system according to claim 1 or 2, wherein the carrier wave is millimeter waves. The transmitters of two or more fixed stations do not transmit the radio signal in the same time zone.
The positioning system according to any one of claims 1 to 3, wherein the transmitting unit that transmits the radio signal is changed over time. The transmission unit of each of the plurality of fixed stations continuously transmits the radio signal,
The positioning system according to any one of claims 1 to 4, wherein the transmission directions of the wireless signals transmitted continuously are different from each other. Each of the plurality of fixed stations
A coding unit that encodes the baseband signal by diffusing the spectrum of the baseband signal based on a predetermined code.
It further has a generation unit that generates the radio signal by superimposing the coded signal encoded by the coding unit on the carrier wave.
The mobile station
An extraction unit that extracts the coded signal from the radio signal received by the reception unit, and an extraction unit.
Any of claims 1 to 5, wherein the extraction unit has a decoding unit that decodes the coded signal into the baseband signal by back-diffusing the spectrum of the extracted coded signal. The positioning system described in one. A mobile station that moves in a room where a reflector that reflects radio signals is installed toward a shielded area between two shields that shield radio signals.
A receiver that receives radio signals transmitted from multiple fixed stations fixed at predetermined indoor positions and whose carrier wave is high frequency, and
A distance calculation unit that calculates the propagation distance from the transmission source to the reception unit for the radio signal received by the reception unit, and a distance calculation unit.
A position calculation unit that calculates the position of the mobile station based on the propagation distances of a plurality of radio signals whose sources are different from each other, which is calculated by the distance calculation unit.
A time calculation unit that calculates the propagation time from the transmission source to the reception unit for the radio signal received by the reception unit, and a time calculation unit.
The time calculation unit calculates based on the propagation time of the radio signal propagated from the fixed station to the receiving unit when the mobile station is stopped at a predetermined position and the propagation time stored in advance. A correction amount calculation unit that calculates a correction amount for correcting the propagation time, and a correction amount calculation unit.
A correction unit that corrects the propagation time calculated by the time calculation unit based on the correction amount calculated by the correction amount calculation unit, and a correction unit that corrects the propagation time calculated by the time calculation unit .
It is provided with an intrusion determination unit that determines whether or not the mobile station has invaded the shielded area.
The distance calculation unit calculates the propagation distance on the basis of a propagation time during which the correcting unit is corrected,
When the intrusion determination unit determines that the mobile station has invaded the shielded area, the position calculation unit calculates the position of the mobile station based on the traveling direction and moving speed of the mobile station. Characterized mobile station. A mobile station that moves in a room where a reflector that reflects radio signals is installed toward a shielded area between two shields that shield radio signals.
A receiver that receives radio signals transmitted from multiple fixed stations fixed at predetermined indoor positions and whose carrier wave is high frequency, and
A distance calculation unit that calculates the propagation distance from the transmission source to the reception unit for the radio signal received by the reception unit, and a distance calculation unit.
A position calculation unit that calculates the position of the mobile station based on the propagation distances of a plurality of radio signals whose sources are different from each other, which is calculated by the distance calculation unit.
A time calculation unit that calculates the propagation time from the transmission source to the reception unit for the radio signal received by the reception unit, and a time calculation unit.
When the mobile station is stopped at a predetermined position, a correction amount calculation unit that calculates a correction amount for correcting the propagation time calculated by the time calculation unit, and a correction amount calculation unit.
A correction unit that corrects the propagation time calculated by the time calculation unit based on the correction amount calculated by the correction amount calculation unit, and a correction unit that corrects the propagation time calculated by the time calculation unit .
It is provided with an intrusion determination unit that determines whether or not the mobile station has invaded the shielded area.
The distance calculation unit calculates the propagation distance based on the propagation time corrected by the correction unit.
The correction amount calculation unit calculates a correction amount in which the position calculated by the position calculation unit indicates the predetermined position when the mobile station is stopped at the predetermined position.
When the intrusion determination unit determines that the mobile station has invaded the shielded area, the position calculation unit calculates the position of the mobile station based on the traveling direction and moving speed of the mobile station. Characterized mobile station.

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