JP2006119006A - Positioning device, system, method, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To ensure accurately positioning calculation by assuming the earth center as one GPS satellite, while suppressing an increase of a storage capacity. <P>SOLUTION: When connection from moving terminals 107a, 107b to a GPS server 102 is established, information of an access point where the moving terminals 107a, 107b are connected is added to a transmission packet by an exclusive protocol, and transmitted to the GPS server 102. The GPS server 102 retrieves an altitude table 103a on the basis of the information of the access point where the moving terminals 107a, 107b are connected, acquires thereby altitude information corresponding to present positions of the moving terminals 107a, 107b, and transmits it to the moving terminals 107a, 107b. When acquiring the altitude information corresponding to the present positions of the moving terminals 107a, 107b, positioning means 108a, 108b performs positioning calculation by assuming the earth center as a satellite. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a positioning device, a positioning system, a positioning method, and a positioning program, and is particularly suitable for application to GPS (global positioning system).

  In recent vehicle-mounted terminal devices and portable terminal devices, it is performed to grasp the current position of a vehicle or a pedestrian by installing a GPS. Further, a navigation function is realized by providing map information to an in-vehicle terminal device or a portable terminal device and displaying a positioning result by GPS on a map. In order to accurately calculate the current position information by GPS, it is necessary to receive radio waves from at least four satellites.

In Patent Document 1, a pseudo distance r _i is measured from radio waves received from n GPS satellites captured by a GPS receiver, and coordinates (x, y, z) of the GPS receiver representing the pseudo distance r _i are disclosed. ) And n functions having the clock error t as a variable, when the occurrence of multipath is detected, the reception represents the pseudorange r _{n + 1} when the center of the earth is regarded as one GPS satellite. A method for suppressing deterioration in positioning accuracy due to the influence of multipath is disclosed by adding one function with machine coordinates as a variable and performing convergence calculation on the total (n + 1) functions. .

Here, in the method of performing the positioning calculation by regarding the earth center as one GPS satellite, the altitude information of the GPS receiver is required. For this reason, there has been a method of measuring the altitude of the GPS receiver by mounting a barometric sensor on the GPS receiver.
JP 2002-333472 A

However, the method of mounting the atmospheric pressure sensor on the GPS receiver increases the cost, and when the atmosphere is unstable, the atmospheric pressure value measured by the atmospheric pressure sensor fluctuates. For this reason, an error occurs in the measured value of the altitude of the GPS receiver, and there is a problem that the positioning accuracy when the center of the earth is regarded as one GPS satellite is deteriorated.
On the other hand, if the GPS receiver has altitude information, it requires altitude information for all areas to which the GPS receiver can move, which requires enormous storage capacity and impairs the portability of the GPS receiver. There was a problem.

  Accordingly, an object of the present invention is to provide a positioning device, a positioning system, a positioning method, and a positioning program that can perform positioning calculation with high accuracy by assuming the center of the earth as one GPS satellite while suppressing an increase in storage capacity. Is to provide.

In order to solve the above-described problem, according to the positioning device according to one aspect of the present invention, a positioning unit that receives radio waves from a satellite and performs positioning calculation assuming that the center of the earth is a satellite, and a communication network And communication means for acquiring altitude information used for the positioning calculation.
This makes it possible to obtain altitude information for the necessary areas only when necessary, and to perform positioning calculations assuming that the center of the earth is a satellite without having the positioning device have altitude information for all areas. It becomes. For this reason, even when the number of satellites necessary for positioning cannot be acquired, positioning calculation can be performed while suppressing an increase in the storage capacity of the positioning device, and the accuracy of positioning calculation can be improved. .

  Further, according to the positioning apparatus of one aspect of the present invention, the positioning unit measures the pseudo distances from the received radio waves from the n number of captured satellites, and sets the coordinates of the current location representing the pseudo distance and the clock error as variables. Is added to the n functions, and one function whose variable is the coordinates of the current location representing the pseudorange with the earth center as one satellite is added. By performing the convergence calculation, the coordinates of the current location and the clock error are calculated as a solution of the (n + 1) simultaneous simultaneous equations.

  This makes it possible to increase the number of functions used for positioning calculation by one without increasing the number of captured satellites. Therefore, it is possible to perform positioning calculation even when the number of satellites necessary for positioning cannot be acquired, and to improve the arrangement state of the satellite even when the number of satellites necessary for positioning can be acquired. And the accuracy of positioning calculation can be improved.

  In addition, according to the positioning system of one aspect of the present invention, a mobile terminal that receives radio waves from a satellite and performs positioning calculation assuming the earth center as a satellite, and mounted on the mobile terminal, a mobile communication network is installed. Communication means for communicating with the base station via the mobile station, and a server for transmitting altitude information used for the positioning calculation to the mobile terminal via the mobile communication network.

  This makes it possible to obtain altitude information of the area where the mobile terminal currently exists from the server only when necessary, and the center of the earth is regarded as a satellite without having the mobile terminal have altitude information of the whole country or the whole world. Positioning calculation can be performed. For this reason, even when the number of satellites necessary for positioning cannot be acquired, positioning calculation can be performed while suppressing an increase in the storage capacity of the mobile terminal, and the accuracy of positioning calculation can be improved. .

The positioning system according to one aspect of the present invention further includes an altitude table provided on the server side, in which altitude information is registered for each communication area handled by the base station.
Thereby, altitude information can be updated according to the movement position of the mobile terminal without giving the mobile terminal any altitude information. For this reason, it is possible to improve the accuracy of altitude information while suppressing an increase in storage capacity of the mobile terminal, and it is possible to improve the accuracy of positioning calculation of the mobile terminal without impairing the portability of the mobile terminal. .

Moreover, according to the positioning system according to one aspect of the present invention, the communication unit transmits information specifying base stations that are mutually connected to the server, and the server corresponds to the base station. Altitude information is transmitted to the mobile terminal.
Accordingly, it is possible to grasp the approximate position of the mobile terminal on the server side without performing positioning on the mobile terminal side. For this reason, it is possible to improve the accuracy of altitude information sent to the mobile terminal, and positioning of the mobile terminal can be performed accurately even when the number of satellites necessary for positioning cannot be acquired.

In the positioning system according to one aspect of the present invention, the mobile terminal uses a previous positioning result as altitude information for the current positioning calculation.
This makes it possible for the mobile terminal to perform the current positioning calculation by regarding the center of the earth as a satellite without accessing the server, and to suppress deterioration in accuracy of altitude information. For this reason, even when the number of satellites necessary for positioning cannot be acquired, positioning can be performed in a short time while suppressing deterioration of positioning accuracy.

  In addition, according to the positioning method according to an aspect of the present invention, the step of capturing n satellites, the step of acquiring altitude information for performing positioning calculation assuming the earth center as a satellite, via a communication network, Measuring a pseudo distance from each of received radio waves from the n captured satellites, generating n functions having variables of current position coordinates and clock error representing the pseudo distance, and the center of the earth (N + 1) by generating one function with the coordinates of the current position representing the pseudorange as a satellite and performing the convergence calculation on the (n + 1) generated functions. And a step of calculating a current position coordinate and a clock error as a solution of the original simultaneous equations.

This makes it possible to perform positioning calculations even when the number of satellites necessary for positioning cannot be acquired, and to improve the arrangement state of the satellites even when the number of satellites necessary for positioning can be acquired. And the accuracy of positioning calculation can be improved.
In addition, according to the positioning program according to one aspect of the present invention, the step of receiving the radio wave from the satellite and performing the positioning calculation on the assumption that the center of the earth is the satellite, and the altitude information used for the positioning calculation via the communication network are obtained. The step of obtaining is executed by a computer.

  As a result, by causing the computer to execute the positioning program, it is possible to perform positioning calculation assuming that the center of the earth is a satellite. For this reason, even when the number of satellites necessary for positioning cannot be acquired, positioning calculation can be performed while suppressing an increase in cost, and the accuracy of positioning calculation can be improved.

Hereinafter, a positioning device and a positioning method according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a schematic configuration of a positioning system according to an embodiment of the present invention.
In FIG. 1, a processing center 101 and base stations 106a to 106c are connected to a communication network 105. The mobile terminals 107a and 107b establish connections with the base stations 106a to 106c, so that the mobile terminals 107a and 107b can communicate with access points such as the base stations 106a to 106c. The processing center 101 is provided with a GPS server 102, a database 103, and a processing terminal 104. Here, the database 103 stores an altitude table 103a in which altitude information for each base station area is registered.

  The mobile terminals 107a and 107b are provided with positioning means 108a and 108b for measuring the current positions of the mobile terminals 107a and 107b, respectively. Here, the positioning means 108a and 108b can receive a radio wave from a satellite and perform a positioning calculation by regarding the center of the earth as a satellite. When the positioning calculation is performed by the positioning means 108a and 108b, the mobile terminals 107a and 107b access the GPS server 102 by establishing a connection with the base stations 106a to 106c, and are registered in the altitude table 103a. The altitude table of the area where the mobile terminals 107a and 107b are located can be acquired.

  Here, when the connection from the mobile terminals 107a and 107b to the GPS server 102 is established, the information of the access point to which the mobile terminals 107a and 107b are connected can be added to the transmission packet by a dedicated protocol and sent to the GPS server 102. . The access point information to which the mobile terminals 107a and 107b are connected includes, for example, a base station that communicates with a mobile phone or a PHS, a base station of a wireless phone, or a telephone number of a wired phone.

Then, the GPS server 102 searches the altitude table 103a based on the information of the access point to which the mobile terminals 107a and 107b are connected, thereby acquiring the altitude table of the current location area of the mobile terminals 107a and 107b. 107a and 107b.
Then, when the positioning means 108a and 108b obtain the altitude information corresponding to the current positions of the mobile terminals 107a and 107b from the altitude table, the positioning means 108a and 108b measure the pseudo distances from the received radio waves from the n satellites captured, respectively. N functions having the coordinates of the current location representing the clock and a clock error as variables are constructed, and one function having the coordinates of the current location representing the pseudorange assuming the earth center as one satellite is added. be able to. Then, by performing convergence calculation for the total (n + 1) functions, the coordinates of the current location and the clock error can be calculated as the solution of the (n + 1) simultaneous simultaneous equations.

  As a result, the mobile terminals 107a and 107b can have altitude information for the necessary area only when necessary, and the center of the earth can be transmitted to the satellite without having the mobile terminals 107a and 107b have altitude information for the whole country or the whole world. This makes it possible to perform positioning calculation. For this reason, even when the number of satellites necessary for positioning cannot be acquired, positioning calculation can be performed while suppressing an increase in the storage capacity of the mobile terminals 107a and 107b, and the accuracy of positioning calculation is improved. be able to.

  The communication network 105 can be a public communication network that performs IP communication, and may be the Internet. Alternatively, it may be a fixed telephone communication network, a mobile communication network, a LAN, or the like. The mobile terminals 107a and 107 may be notebook personal computers or desktop personal computers, and may be video cameras, digital cameras, mobile phone terminals, PDAs (Personal Data Assistants), or the like.

FIG. 2 is a diagram illustrating a configuration example of an altitude table according to an embodiment of the present invention.
In FIG. 2, the altitude table for each base station is composed of a header and altitude data, and the altitude values of the subdivided cells are stored in areas where communication with the base stations 106a to 106c is possible. Here, the base station number and the coordinate values (Lat_b, Lon_b, Alt_b) of the base stations 106a to 106c are registered in the header. The coordinate values (Lat_b, Lon_b, Alt_b) of the base stations 106a to 106c can be represented by (latitude, longitude, altitude). The header stores the width Width and length Length of the subdivided cells, and the coordinates of the upper left cell (Lat_1, Lon_1) and the coordinates of the lower right cell (Lat_2, Lon_2) of each area. Has been. The altitude data can be composed of altitude values of each cell arranged in order from the upper left cell to the lower right cell.

When searching the altitude of the given coordinate value (Lat, Lon) from the altitude table, the given coordinate value (Lat, Lon) is obtained by using the upper left cell coordinates (Lat_1, Lon_1) and the lower right cell coordinates (Lat_2). , Lon_2), the altitude value Alt_b of the base station can be returned to the mobile terminals 107a and 107b when the area is exceeded.
On the other hand, if the given coordinate value (Lat, Lon) is in the area, the cell index in which the given coordinate value (Lat, Lon) exists is calculated by the following formula.

Then, the altitude value corresponding to the cell index can be searched from the base station area altitude table, and the altitude value Alt_i can be returned to the mobile terminals 107a and 107b.
FIG. 3 is a block diagram showing a schematic configuration of the GPS receiver of FIG.
In FIG. 3, a GPS signal transmitted from a GPS satellite is received via the antenna 1. The GPS signal received by the antenna 1 is input to the low noise amplifier 2 and amplified by the low noise amplifier 2. The GPS signal amplified by the low noise amplifier 2 is input to the band pass filter 3, and a desired frequency is extracted by the band pass filter 3, and then output to the mixer 4.

  On the other hand, the reference signal output from the reference oscillator 16 is input to the PLL circuit 17, and the reference signal output from the reference oscillator 16 is divided or multiplied by the PLL circuit 17 to generate a frequency signal having a constant frequency. Is done. The PLL circuit 17 is controlled by the CPU 14, and the frequency of the frequency signal generated by the PLL circuit 17 can be changed by controlling the frequency division ratio and the like in the PLL circuit 17.

Then, the frequency signal generated by the PLL circuit 17 is output to the mixer 4, and the frequency signal generated by the PLL circuit 17 is mixed with the GPS signal output from the bandpass filter 3, thereby obtaining a predetermined signal. A GPS signal having a frequency (1.5 GHz band) is down-converted (frequency conversion) into a first intermediate frequency signal.
The first intermediate frequency signal output from the mixer 4 is input to the auto gain control amplifier 5 and amplified to a predetermined amplitude. The auto gain control amplifier 5 is controlled by the CPU 14 and can adjust the amplification factor of the auto gain control amplifier 5 according to the situation of the demodulation circuit 10. The first intermediate frequency signal amplified by the auto gain control amplifier 5 is input to the band pass filter 6, and a desired frequency is extracted by the band pass filter 6, and then output to the mixer 7.

  The frequency signal generated by the PLL circuit 17 is output to the mixer 7, and the frequency signal generated by the PLL circuit 17 is mixed with the first intermediate frequency signal output from the bandpass filter 6. The first intermediate frequency signal is downconverted to the second intermediate frequency signal. The PLL circuit 17 can output a reference signal having a frequency lower than that of the reference signal output to the mixer 4 to the mixer 7.

  The second intermediate frequency signal output from the mixer 7 is input to the low-pass filter 8, and after the high-frequency component is removed by the low-pass filter 8, it is output to the A / D converter 9. The second intermediate frequency signal output from the low pass filter 8 is digitized by the A / D converter 9 and then output to the demodulation circuit 10. Then, when the second intermediate frequency signal is input, the demodulation circuit 10 can perform a GPS signal demodulation process based on the control from the CPU 14.

  The demodulating circuit 10 multiplies the digitized second intermediate frequency signal by a PN code (pseudo random code) to perform spectrum despreading processing, and BPSK-demodulates the signal subjected to spectrum despreading processing, By performing GPS signal demodulation processing, it is possible to obtain almanac data, ephemeris data, GPS time data, and the like transmitted from GPS satellites.

  Here, the PN code used for the spectrum despreading process takes a value determined for each GPS satellite, and a GPS satellite that receives a GPS signal can be selected by selecting this PN code. A GPS satellite that receives a GPS signal can be selected based on control from the CPU 14. The demodulation circuit 10 can simultaneously perform demodulation processing from 8 channels to a maximum of 16 channels, and can simultaneously demodulate GPS signals transmitted from a plurality of GPS satellites.

  Next, the transmission data demodulated by the demodulation circuit 10 is sent to the arithmetic processing unit 11, the propagation time of the GPS signal sent from each GPS satellite is calculated, and the position of each GPS satellite and each GPS satellite Information on correction values (troposphere correction value, ionosphere correction value, GPS time correction value) necessary for calculating the distance to the GPS receiver is obtained. Then, the arithmetic processing unit 11 can obtain the current position of the GPS receiver (mobile terminal) and the correction time of the GPS time of the GPS receiver based on the obtained information.

  In this case, since there are three unknowns (x, y, z) at the position of the GPS receiver, it is necessary to obtain four unknowns together with the correction time t of the GPS time of the GPS receiver. For this reason, GPS signals transmitted from four or more GPS satellites are usually required in order to perform positioning calculation of the GPS receiver. When there are four GPS satellites used for positioning calculation, four simultaneous equations are created based on the corrected distance data between each GPS satellite and the GPS receiver and the position data of each GPS satellite. Is done. Then, by solving these four simultaneous equations, the current position of the GPS receiver and the GPS time correction time of the GPS receiver (offset value with respect to GPS time) can be obtained.

  In addition, assuming that the center of the earth is a single satellite, it is possible to add one function with the coordinates of the current location representing the pseudorange as a variable, and a total of five simultaneous equations can be created. Then, by solving these five simultaneous equations, the current position of the GPS receiver and the correction time of the GPS time of the GPS receiver can be obtained, and the positioning accuracy can be improved. Further, by assuming that the center of the earth is one satellite, positioning of the GPS receiver can be performed even when only three GPS satellites can be captured, and the positioning time can be shortened.

  On the other hand, when performing positioning calculation, the CPU 14 accesses the GPS server 102 by establishing communication with the base stations 106a to 106c, and specifies the positions of the base stations 106a to 106c that have established connections with the mobile terminals 107a and 107b. The transmission data to which the information is added is sent to the baseband signal processing unit 23. When the baseband signal processing unit 23 receives the transmission data from the CPU 14, the baseband signal processing unit 23 performs baseband signal processing on the transmission data and then sends the transmission data to the radio unit 22. Then, modulation processing of transmission data output from the baseband signal processing unit 23 is performed by the radio unit 22 and transmitted to the outside via the communication antenna 21. The transmission data sent to the outside via the communication antenna 21 is received by the base stations 106 a to 106 c and transmitted to the GPS server 102 via the communication network 105. When the GPS server 102 receives the information for specifying the positions of the base stations 106a to 106c from the mobile terminals 107a and 107b, the GPS server 102 uses the positions of the base stations 106a to 106c as the given coordinate values (Lat_b, Lon_b). By searching the table 103a, the altitude table 12a of the base station area corresponding to the current positions of the mobile terminals 107a and 107b is acquired and transmitted to the base stations 106a to 106c via the communication network 105. When the base stations 106a to 106c receive the altitude table 12a, the altitude table 12a is transmitted to the mobile terminals 107a and 107b.

  When the altitude table 12a corresponding to the positions of the mobile terminals 107a and 107b is transmitted from the base stations 106a to 106c, the altitude table 12a is received by the communication antenna 21. The altitude table 12 a received via the communication antenna 21 is sent to the radio unit 22, and demodulation processing is performed by the radio unit 22. Then, the altitude table 12a output from the radio unit 22 is sent to the baseband signal processing unit 23, and after baseband signal processing is performed by the baseband signal processing unit 23, it is output to the CPU 14. When the CPU 14 receives the altitude table 12a, the altitude table 12a can be stored in the memory 12.

  Then, when the altitude table 12a is stored in the memory 12, the altitude table 12a is used to construct a function with the coordinates of the current location representing the pseudorange when the center of the earth is regarded as one satellite as variables. Can do. When a function when the center of the earth is regarded as one satellite is constructed, the current position of the mobile terminals 107a and 107b can be calculated as a solution of simultaneous equations including the function constructed for the captured satellite. And CPU14 can memorize | store the positioning result 12b in the memory 12, if the arithmetic processing part 11 calculates the present position of the mobile terminals 107a and 107b.

  This makes it possible to obtain altitude information of the area where the mobile terminals 107a and 107b currently exist from the GPS server 102 only when necessary, without having the mobile terminals 107a and 107b have altitude information for the whole country or the whole world. It is possible to perform positioning calculation by regarding the earth center as a satellite. For this reason, even when the number of satellites necessary for positioning cannot be acquired, positioning calculation can be performed while suppressing an increase in storage capacity of the mobile terminals 107a and 107b, and the arrangement of the acquired satellites can be determined. Even in a bad case, the accuracy of positioning calculation can be improved.

  When the current positioning result 12b is stored in the memory 12, the current positioning result 12b may be used as the altitude information 12a for the next positioning calculation when performing the next positioning. As a result, the mobile terminals 107a and 107b can perform the next positioning calculation assuming that the center of the earth is a satellite without accessing the GPS server 102, and can suppress deterioration in accuracy of the altitude information 12a. It becomes. For this reason, even when the number of satellites necessary for positioning cannot be acquired, positioning calculation can be performed in a short time while suppressing deterioration of positioning accuracy.

FIG. 4 is a diagram for explaining a GPS positioning method according to an embodiment of the present invention.
In FIG. 4, the position of each of the GPS satellites SV1 to SV4 at an arbitrary time can be accurately obtained from the navigation message that the satellites SV1 to SV4 continuously transmit to the earth.
The navigation signal transmitted from each of the GPS satellites SV1 to SV4 includes the precise transmission time of the signal in addition to the ephemeris data including the almanac and ephemeris. The distance from the mobile terminal 107a to each of the GPS satellites SV1 to SV4 can be determined from this transmission time included in each navigation signal. That is, by using the transmission time of the navigation signal and the reception time when the mobile terminal 107a receives the navigation signal, the propagation delay time of the navigation signal can be calculated. Then, by multiplying the propagation delay time of the navigation signal by the propagation speed of the navigation signal, the pseudo distance from the GPS satellites SV1 to SV4 that are transmitting the navigation signal to the mobile terminal 107a can be obtained.

  Here, since the clock of the mobile terminal 107a is not completely synchronized with the GPS, the propagation delay time of the navigation signal includes a certain offset time. Further, the signal propagation time is delayed due to the navigation signal passing through the atmosphere. Therefore, the pseudo distance includes the true distance from the GPS satellites SV1 to SV4 to the mobile terminal 107a, the offset time of the mobile terminal 107a, the navigation signal propagation delay time, and the GPS of the clock mounted on each GPS satellite SV1 to SV4. The error from the time is included.

  Here, when the navigation signal is decoded, a troposphere correction value, an ionosphere correction value, and a GPS time correction value are obtained. Since there are four unknowns combining the clock error tu of the remaining mobile terminal 107a and the three-dimensional position (x, y, z) of the mobile terminal 107a with respect to the center of the earth, the three-dimensional of the mobile terminal 107a In order to obtain the position, it is necessary to acquire at least four GPS satellites SV1 to SV4. Then, by using two pieces of information from the at least four GPS satellites SV1 to SV4 (position information and pseudo distance of the GPS satellites SV1 to SV4), the position of the mobile terminal 107a can be determined by triangulation. it can.

  In order to determine the current position of the mobile terminal 107a using this triangulation method, the following three steps are required. First, the position of at least four GPS satellites SV1 to SV4 within the field of view of the mobile terminal 107a is determined from 24 GPS satellites SV1 to SV4 orbiting around the earth. Second, the distance from the mobile terminal 107a to each of the GPS satellites SV1 to SV4 is determined. Thirdly, the position of the mobile terminal 107a with respect to the center of the earth is geometrically determined from the information obtained in the first and second steps.

  The estimation accuracy of the position of the mobile terminal 107a depends on the number of selected GPS satellites SV1 to SV4 and the geometrical arrangement of the GPS satellites SV1 to SV4 in the sky. For this reason, the estimation accuracy of the position of the mobile terminal 107a with respect to the center of the earth can be improved by using more GPS satellites SV1 to SV4 for the position calculation of the mobile terminal 107a. Here, the pseudo distance measPRj between the GPS satellite SVj and the mobile terminal can be expressed by the following equation (1).

... (1)

However,
: Coordinates (x, y, z) of satellite SVj: coordinates of mobile terminal 107a
: Clock bias of the mobile terminal 107a.

And
And the nonlinear equation (1) by Taylor expansion
The following equation (2) is obtained.

... (2)

  Therefore, when the formula (2) is modified, the following formula (3) is obtained.

... (3)
Here, the difference between the pseudorange and the Euclidean distance is

age,
,
,
,
Assuming

... (4)

It becomes. Therefore, when the equation (4) is modified, the following equation (5) is obtained.

... (5)

  Since equation (5) is established for each satellite SVj being received, equation (5) can be represented by a matrix such as the following equation (6).

... (6)

  On the other hand, if positioning is performed assuming that the center of the earth is one satellite, the following equation (7) can be obtained.

... (7)

  However, A is the long radius (= 6378137.0 m) of the earth ellipsoid (WGS-84 in the case of GPS), and B is the short radius (= 6357562.314 m) of the earth ellipsoid. Then, by multiplying the expression (7) by AB, the following expression (8) can be obtained.

... (8)

  Here, the equation (8) is expanded to the tailor,

Is the altitude value of the GPS receiver, the following equation (9) can be obtained.

... (9)

However,
It is.

Then, convergence calculation is performed on a total of (n + 1) functions obtained by adding the function of equation (9) obtained by assuming the earth center as one satellite to the n functions of equation (6). n + 1) The position of the mobile terminal 107a and the clock bias can be approximately calculated as a solution of the original simultaneous equations.

FIG. 5 is a diagram showing a relationship between altitude error and position error according to an embodiment of the present invention. P1 indicates the relationship between the altitude error and the position error when the earth center is used for positioning, and P2 indicates the relationship between the altitude error and the position error when the earth center is not used for positioning.
In FIG. 5, when the earth center is not used for positioning, the position error of the mobile terminal 107a is 144.10 m. On the other hand, when the center of the earth is used for positioning, if the altitude value of the mobile terminal 107a is correct, the position error of the mobile terminal 107a is only 7.87 m. However, if the altitude value of the mobile terminal 107a is not correct, the positioning result error also increases in proportion to the altitude value error. For this reason, the accuracy of altitude information affects the positioning accuracy, and as the correct altitude value is used, the positioning accuracy can be improved.

FIG. 6 is a flowchart showing a positioning method using server assistance according to an embodiment of the present invention.
In FIG. 6, when the positioning means 108a and 108b in FIG. 1 perform positioning of the mobile terminals 107a and 107b, the positioning means 108a and 108b determine whether the satellites necessary for positioning have been captured or whether the captured satellites are well positioned (step). S1). If the satellites can be acquired as many as necessary for positioning and the arrangement of the acquired satellites is good, the positioning calculation is performed by solving the equation (6) for the satellites (step S5).

  On the other hand, if the number of satellites necessary for positioning cannot be acquired or the positions of the acquired satellites are poor, the positioning means 108a and 108b determine whether the altitude table 12a is stored in the memory 12 (step S2). . And when the altitude table 12a is not memorize | stored in the memory 12, the altitude table 12a of the location area of the mobile terminals 107a and 107b is acquired from the GPS server 102 (step S6). Then, the altitude values of the mobile terminals 107a and 107b are obtained from the altitude table 12a, and the function of the formula (9) is constructed by regarding the earth center as one GPS satellite (step S7). And positioning calculation is performed by adding (9) Formula to (6) Formula (step S5).

  On the other hand, when the altitude table 12a is stored in the memory 12, the mobile terminals 107a and 107b determine whether they have entered the areas of other base stations 106a to 106c (step S3). When the mobile terminals 107a and 107b enter the area of another base station 106a to 106c, the altitude table 12a is acquired from the GPS server 102 (step S6), and the positioning calculation is performed by assuming the center of the earth as one GPS satellite. (Steps S7 and S5).

  On the other hand, when the mobile terminals 107a and 107b are not in the area of another base station 106a to 106c, the altitude value of the mobile terminals 107a and 107b is obtained from the altitude table 12a already stored in the memory 12, and one earth center is obtained. As a GPS satellite, a function of equation (9) is constructed (step S4). And positioning calculation is performed by adding (9) Formula to (6) Formula (step S5).

FIG. 7 is a flowchart showing a method for acquiring altitude information according to an embodiment of the present invention. Steps S11 to S16 shown on the left side of FIG. 7 are operation flows by the mobile terminals 107a and 107b, and steps S21 to S21 shown on the right side. S24 is an operation flow by the GPS server 102.
In FIG. 7, when there is no altitude table in high-precision positioning or when the mobile terminals 107a and 107b enter the areas of different base stations 106a to 106c, the mobile terminals 107a and 107b determine that accurate altitude information is required ( In step S11), a connection is established with the GPS server 102 using a dedicated protocol (step S12). Then, when establishing a connection with the GPS server 102, the mobile terminals 107a and 107b send a transmission packet requesting the altitude table 12a to the GPS server 102 (step S13).

  When the GPS server 102 receives a transmission packet for requesting the altitude table 12a from the mobile terminals 107a and 107b (step S21), the GPS server 102 detects the base station number from the received packet (step S22). Then, the GPS server 102 searches the altitude table 103a based on the base station number, thereby acquiring the altitude table 12a of the area that the base stations 106a to 106c established with the connection with the mobile terminals 107a and 107b have (step). S23). Then, the GPS server 102 incorporates the altitude table 12a into the transmission packet, and sends the transmission packet to the mobile terminals 107a and 107b via the communication network 105 (step S24).

  Upon receiving the reply packet sent from the GPS server 102 (step S14), the mobile terminals 107a and 107b extract the altitude table 12a included in the reply packet and store it in the memory 12 of FIG. 3 (step S15). ). Then, the altitude values of the mobile terminals 107a and 107b are obtained from the altitude table 12a stored in the memory 12, and the function of the formula (9) is constructed by regarding the earth center as one GPS satellite. And positioning calculation is performed by adding (9) Formula to (6) Formula (step S16).

FIG. 8 is a flowchart illustrating a positioning method that does not use server assistance according to an embodiment of the present invention.
In FIG. 8, when the positioning means 108a and 108b in FIG. 1 perform positioning of the mobile terminals 107a and 107b, the positioning means 108a and 108b determine whether the satellites necessary for positioning have been captured or whether the captured satellites are well positioned (step). S31). If the satellites can be acquired as many as necessary for positioning and the arrangement of the acquired satellites is good, the positioning calculation is performed by solving the equation (6) for these satellites (step S33).

  On the other hand, if the number of satellites necessary for positioning cannot be acquired or the positions of the acquired satellites are poor, the altitude values of the mobile terminals 107a and 107b are obtained from the previous positioning result 12b stored in the memory 12, and Is constructed as a single GPS satellite, thereby constructing a function of equation (9) (step S32). And positioning calculation is performed by adding (9) Formula to (6) Formula (step S33).

1 is a block diagram showing a schematic configuration of a positioning system according to an embodiment of the present invention. The figure which shows the structural example of the altitude table which concerns on one Embodiment of this invention. The block diagram which shows schematic structure of the mobile terminal of FIG. The figure explaining the positioning method of GPS. The figure which shows the relationship between an altitude error and a position error. The flowchart which shows the positioning method using server assistance. The flowchart which shows the acquisition method of altitude information. The flowchart which shows the positioning method which does not use a server assist.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 101 Processing center, 102 GPS server, 103 Database, 103a Altitude table, 104 Processing terminal, 105 Communication network, 106a-106c Base station, 107a, 107b Mobile terminal, 108a, 108b Positioning means, 1 GPS antenna, 2 Low noise amplifier, 3 , 6 Band pass filter, 4, 7 mixer, 5 Auto gain control amplifier, 8 Low pass filter, 9 A / D converter, 10 Demodulator circuit, 11 Arithmetic processing unit, 12 Memory, 12a Altitude information, 12b Positioning result, 16 reference Transmitter, 17 PLL circuit, 21 communication antenna, 22 radio unit, 23 baseband processing unit, SV1 to SV4 GPS satellite

Claims (8)

A positioning means that receives radio waves from a satellite and performs positioning calculation by regarding the earth center as a satellite,
A positioning device comprising: communication means for acquiring altitude information used for the positioning calculation via a communication network.   The positioning means measures a pseudo distance from each of received radio waves from n satellites that have been captured, and has one earth center for n functions that use the coordinates of the current location representing the pseudo distance and a clock error as variables. By adding one function with the coordinates of the current location representing the pseudorange as a satellite of the variable as a variable, and performing a convergence calculation on these (n + 1) functions, the solution of the (n + 1) simultaneous equations The positioning device according to claim 1, wherein coordinates of the current location and a clock error are calculated. A mobile terminal that receives radio waves from a satellite and performs positioning calculation by regarding the center of the earth as a satellite,
A communication means mounted on the mobile terminal for communicating with a base station via a mobile communication network;
A positioning system comprising: a server that transmits altitude information used for the positioning calculation to the mobile terminal via the mobile communication network.   4. The positioning system according to claim 3, further comprising an altitude table provided on the server side, in which altitude information is registered for each communication area handled by the base station.   The communication means transmits information specifying base stations with which connection is established to the server, and the server transmits altitude information corresponding to the base station to the mobile terminal. Item 5. The positioning system according to item 4.   The positioning system according to any one of claims 3 to 5, wherein the mobile terminal uses a previous positioning result as altitude information of the current positioning calculation. acquiring n satellites;
Obtaining altitude information via a communication network for positioning calculation with the earth center as a satellite;
Measuring a pseudo distance from each of received radio waves from n captured satellites; generating n functions having variables of current position coordinates representing the pseudo distance and a clock error;
Generating a function having the coordinates of a current location representing a pseudorange as a single satellite with the center of the earth as a variable;
A step of calculating a coordinate of a current location and a clock error as a solution of an (n + 1) -ary simultaneous equation by performing a convergence calculation on the generated (n + 1) functions. Receiving radio waves from the satellite, performing positioning calculation with the earth center as a satellite,
A positioning program for causing a computer to execute the step of acquiring altitude information used for the positioning calculation via a communication network.