JP2001333443A - Position calculation method, position calculation device and mobile terminal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a position calculation method by which a position of a mobile terminal can simply be calculated with excellent accuracy and to provide a position calculation device and the mobile terminal that can calculate its own position. SOLUTION: In the case that base stations receptible by a PHS terminal 10 are three; CS1, CS2, CS3 in a position information provision system, whether or not distances r1, r2, r3 between current coordinates P0 of the PHS terminal 10 and the base stations CS1, CS2, CS3 except the shortest distance are a multiple of 2.5 or smaller of the shortest distance is discriminated. In the case that the distances except the shortest distance have a value of a multiple of 2.5 or over of the shortest distance, an intermediate coordinate P12 corresponding to a ratio of the distance r1 to the distance r2 and an intermediate coordinate P13 corresponding to a ratio of the distance r1 to the distance r3 are calculated and the current coordinate of the PHS terminal is calculated on the basis of a ratio of the distance of virtual base stations placed at the intermediate coordinates P12, P13 to the position of the PHS terminal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a position calculating method for calculating the position of a portable terminal, a position calculating device, and a portable terminal for calculating the position of the terminal. The present invention relates to a calculation device and a PHS terminal that calculates its current position.

[0002]

2. Description of the Related Art In recent years, PHS (Personal handy phone)
A location information providing service using a terminal is provided.
The location information providing service refers to the fact that the effective range (so-called “cell”) of radio waves of a base station in a PHS telephone system is relatively narrow, and the center station in the PHS telephone system has a PHS held by a person who wants to know the location. By obtaining information of a base station capable of communicating with the PHS terminal from the terminal together with information of the received electric field strength, the position of the person who wants to know the position of the map information corresponding to the cell of one base station expected to be closest This is a service provided as information.

[0003]

However, in this type of location information providing service, the location of the PHS terminal can be relatively wide based on the location information of one base station expected to be closest to the PHS terminal. Since it was determined, the position of the PHS terminal could not be obtained with high accuracy. Therefore, the present invention has been made in view of the above-described circumstances, and provides a position calculation method, a position calculation device, and a mobile terminal that calculates its own position, which can easily and accurately calculate the position of a mobile terminal. The purpose is to do.

[0004]

According to a first aspect of the present invention, there is provided a position calculating method for calculating a position of a portable terminal which communicates with a plurality of base stations. A specific information obtaining step of obtaining, from the signal, specific information for specifying at least one or a plurality of the base stations transmitting a signal received by the mobile terminal; and transmitting from the base station specified by the specific information in the mobile terminal. An electric field intensity detecting step of detecting a received electric field intensity of a signal, a distance calculating step of calculating a distance between the portable terminal and a base station specified by the specific information based on the received electric field strength, and A position information acquisition step of acquiring position information of the base station specified by the specific information from the position information of the plurality of base stations, and if the number of base stations specified by the specific information is plural, A position ratio calculating step of calculating a position of the mobile terminal from the obtained position information of the plurality of base stations by a calculated ratio of a distance between the mobile terminal and the plurality of base stations specified by the specific information. Features. The invention according to claim 2 is the position calculation method according to claim 1, wherein, in the position calculation step, when the number of base stations specified by the specific information is three, the calculated mobile terminal and the specific information It is determined whether or not the distance excluding the shortest distance among the distances to the three base stations specified by is equal to or less than 2.5 times the shortest distance, and the distance excluding the shortest distance is the shortest. When the distance is equal to or less than 2.5 times the distance, the position of the portable terminal is calculated as the position of the portable terminal, or the center of gravity of a triangle having the obtained positions of the three base stations as vertices. I have. According to a third aspect of the present invention, in the position calculating method according to the first or second aspect, in the distance calculating step,
Acquiring the transmission power information of the base station specified by the specific information from the transmission power information of the plurality of base stations held in advance, based on the acquired transmission power information and the detected received electric field strength, The distance between the mobile terminal and the base station specified by the specific information is calculated.

[0005] The invention according to claim 4 is the invention according to claims 1 to 3.
The position calculation method according to any one of the above, further comprising a position display step of displaying the calculated position of the mobile terminal by the mobile terminal. The invention according to claim 5 is a position calculating device that calculates a position of an arbitrary portable terminal that communicates with a plurality of base stations, and wherein at least one or a plurality of the portable terminals transmit a signal received by the portable terminal. Information receiving means for receiving a signal including specific information for specifying the base station, and information on a received electric field strength of a signal transmitted from the base station specified by the specific information in the portable terminal; Distance calculating means for calculating a distance between the mobile terminal and each base station specified by the specific information, position information holding means for holding position information of all the base stations, and the position information holding Position information obtaining means for obtaining the position information of the base station specified by the specific information from the position information held by the means, and when the number of base stations specified by the specific information is plural, the calculated Carrying Position calculation means for calculating the position of the mobile terminal from the acquired position information of the plurality of base stations, based on a ratio of the distance between the terminal and the plurality of base stations specified by the specific information. . According to a sixth aspect of the present invention, in the position calculating device according to the fifth aspect, when the number of base stations specified by the specific information is three, the position calculating means uses the calculated portable terminal and the specific information. It is determined whether the distance excluding the shortest distance among the distances to the three specified base stations is equal to or less than 2.5 times the shortest distance, and the distance excluding the shortest distance is the shortest distance. When the value is 2.5 times or less, the center of gravity of a triangle having the obtained positions of the three base stations as vertices or a predetermined range including the center of gravity is calculated as the position of the portable terminal. . The invention according to claim 7 is the invention according to claim 5 or 6
The position calculating device according to claim 1, further comprising a power information holding unit that holds transmission power information of all the base stations, wherein the distance calculation unit performs the identification from transmission power information held by the power information holding unit. Acquiring transmission power information of the base station specified by the information, and calculating a distance between the mobile terminal and the base station specified by the specific information, based on the obtained transmission power information and the received electric field strength. It is characterized by.

[0006] The invention according to claim 8 is the invention according to claims 5 to 7.
The position calculating device according to any one of the above, further comprising a position transmitting unit that transmits a position signal including the calculated position of the mobile terminal to the mobile terminal. According to a ninth aspect of the present invention, in the position calculation device according to any one of the fifth to eighth aspects, the position of the PHS terminal as the portable terminal is calculated. Claim 10
The described invention is a portable terminal that performs communication with a plurality of base stations to calculate its own position, a receiving unit that receives a signal transmitted from the base station, and a receiving unit that receives the signal. Specific information obtaining means for obtaining, from the signal, specific information specifying at least one or a plurality of the base stations transmitting a signal, and detecting a reception electric field strength of a signal transmitted from the base station specified by the specific information Electric field strength detecting means, distance calculating means for calculating a distance between the portable terminal and the base station specified by the specific information based on the received electric field strength, and a position for holding position information of all the base stations Information holding means, position information obtaining means for obtaining the position information of the base station specified by the specific information from the position information held by the position information holding means, and the base station specified by the specific information In the case where there are a plurality, the position of the mobile terminal is calculated from the obtained position information of the plurality of base stations, based on the calculated ratio of the distance between the mobile terminal and the plurality of base stations specified by the specific information. And a position calculating means.

According to an eleventh aspect of the present invention, in the portable terminal according to the tenth aspect, when the number of base stations specified by the specific information is three, the position calculating means determines whether the number of base stations is equal to the calculated mobile terminal. It is determined whether the distance excluding the shortest distance among the distances to the three base stations specified by the specific information is equal to or less than 2.5 times the shortest distance, and the distance excluding the shortest distance is If the distance is equal to or smaller than 2.5 times the shortest distance, the position of the portable terminal is calculated as the position of the center of gravity or a predetermined range including the position of the center of gravity of the triangle having the obtained positions of the three base stations as vertices. It is characterized by. The invention according to claim 12 is the invention according to claim 10 or 11
The portable terminal according to claim 1, further comprising power information holding means for holding the transmission power information of all the base stations, wherein the distance calculation means, the transmission power information held in the power information holding means from among the transmission power information the identification information Acquiring the transmission power information of the base station specified in the, based on the acquired transmission power information and the received electric field strength, to calculate the distance between the mobile terminal and the base station specified by the specific information Features. The invention according to claim 13 is the portable terminal according to any one of claims 10 to 12, wherein the portable terminal comprises:
It is a PHS terminal.

[0008]

Embodiments of the present invention will be described below with reference to the drawings.

(1) Embodiment (1-1) Configuration of Embodiment FIG. 1 is a schematic configuration diagram of a position information providing system according to an embodiment of the present invention. This position information providing system 1
This is a system for providing a location information providing service as one of the PHS telephone services.
It comprises a location information providing server 30 for transmitting the location information DP of the HS terminal 10. Although only one PHS terminal 10 is shown in this figure, there are actually a plurality of PHS terminals 10. The PHS network in FIG. 1 controls a configuration other than the PHS terminal 10 in the PHS telephone system, that is, a base station CSk (k = 1 to n) or a base station CSk (not shown) installed in a public telephone box or a building. Mobile communication control device.

The PHS terminal 10 has a function of collecting receivable base station information DCS in addition to the function of a normal PHS terminal, and the position information DS received from the position information providing server 30.
The PHS terminal has a function of displaying a current position based on P. That is, as shown in FIG. 2, the PHS terminal 10 includes an antenna 11, a radio unit 12 for transmitting and receiving radio waves, and a switch unit 13 for switching between transmission and reception.
, Transmission unit 14, transmission data processing unit 15, microphone 1
6, a reception unit 17, a reception data processing unit 18, a speaker 19, a display unit 20, a key 21, a control unit 22 for controlling the entire terminal 10, and a memory 23. In addition to the functions such as the communication function and display function of the PHS terminal, a function of collecting receivable base station information DCS, and a function of the position information D received from the position information providing server 30
It has a function of displaying the current position based on P.

[0011] The location information providing server 30 has a PHS
When the terminal 10 receives the collected base station information DCS, it calculates the current coordinates of the PHS terminal 10 based on the received base station information DCS, and uses the calculated position as the position information DP.
It is a server that provides a service to be transmitted to the HS terminal 10. As shown in FIG. 1, the location information providing server 30 includes, as shown in FIG. 1, a communication server 31 for communicating with the PHS terminal 10 via the PHS network, and location information of all base stations CSk in the PHS telephone system (each base station CSk). C
A base station position information database 32 storing a unique number IDk of Sk, latitude / longitude coordinates Pk, and base station transmission power CSPk), and base station information D transmitted from the PHS terminal 10.
A coordinate search engine 33 that calculates the current coordinates P0 of the PHS terminal 10 with reference to the base station position information database 32 based on the CS is provided.

(1-2) Operation of Embodiment Next, the operation of the position information providing system 1 will be described. First, in the location information providing system 1, a predetermined key 2 of the PHS terminal 10 is used by the user to acquire the location information DP.
When the PHS terminal 10 is operated, the PHS terminal 10 is controlled to the receiving state by the control unit 22, and up to three receivable base stations CSj (j = 1 to 3) among the signals transmitted from each base station CSk.
m; m <= 3) The signal transmitted from the reception data processing unit 18 is fetched via the antenna 11, the radio unit 12, the switch unit 13, and the reception unit 17. Note that the number of receivable base stations CSj varies depending on the number of base stations CSk around the PHS terminal 10, the inside and outside of a building, the influence of a building, and the like. Then, the PHS terminal 10 extracts the unique number IDj of the base station CSj from the signal transmitted from the base station CSj which can be received by the reception data processing unit 18, and receives the electric field strength of the signal transmitted from the base station CSj. Ej is detected, and the unique number IDj and the received electric field strength Ej are registered in the memory 23 as the base station information DCS. Next, P
The HS terminal 10 is controlled to a transmission state by the control unit 22 and transmits the base station information DCS stored in the memory 23 to the transmission data processing unit 15, the transmission unit 14, the switch unit 13, and the radio unit 1.
2 and to the position information providing server 30 via the antenna 11.

In the location information providing server 30, when the communication server 31 receives the base station information DCS transmitted from the PHS terminal 10 via the PHS network,
Base station database 32 by coordinate search engine 33
Is referred to, and the unique number ID included in the base station information DCS
The latitude and longitude coordinates Pj of the base station CSj and the base station transmission power CSPj corresponding to j are obtained. In the position information providing server 30, the coordinate search engine 33 calculates the distance rj between the current coordinate P0 of the PHS terminal 10 and each base station CSj using the following equation.

Ej = K · CSPj ^1/2 / rj (1) where K is a space propagation coefficient.

Next, the position information providing server 30 determines the distance rj between the current coordinates P0 of the PHS terminal 10 obtained by the coordinate search engine 33 and each base station CSj, and the base station CSj.
The current coordinates P0 of the PHS terminal 10 are calculated based on the latitude / longitude coordinates Pj. In the case of a PHS telephone system in which the base station transmission power CSPk is the same for all base stations CSk, the base station transmission power CSPj in equation (1) may be a constant value. Needless to say, it is only necessary to include it in the location information of the base station location information database 32. Here, when calculating the current coordinates P0 of the PHS terminal 10, the position information providing server 30 determines the PHS terminal according to the number of obtained distances rj, that is, the number of base stations CSj that the PHS terminal 10 can receive. Ten calculation methods of the current coordinates P0 are selected. That is, the location information providing server 30
As shown in (A), when the PHS terminal 10 can receive two base stations CSj, for example, the base stations CS1 and CS2, the coordinate search engine 33 uses the distance r as described above.
1, r2 and the latitude and longitude coordinates P of each base station CS1, CS2
After acquiring P1 and P2, the PHS terminal 1 is obtained using the following equation.
The current coordinate P0 of 0 is calculated.

P0 = r2 · P1 / (r1 + r2) + r1 · P2 / (r1 + r2) (2)

Therefore, the location information providing server 30 sets the PH
Based on the ratio of the distance r1 to the distance r2 between the current coordinates P0 of the S terminal 10 and each of the base stations CS1 and CS2, each of the base stations CS1,
The current coordinates P0 can be accurately calculated from the latitude and longitude coordinates P1 and P2 of CS2.

On the other hand, the location information providing server 30
As shown in FIG. 3B, there are three base stations CSj that can be received by the PHS terminal 10, for example, the base stations CS1 and CS
2, CS3, the distances r1, r2, r3 and the respective base stations CS1, C2 are determined by the coordinate search engine 33 as described above.
After acquiring the latitude and longitude coordinates P1, P2 and P3 of S2 and CS3, it is first determined whether or not the following determination condition A is satisfied. The reason for performing the determination of the determination condition A will be described later.

Judgment condition A: rx, ry ≦ 2.5 · rz (3) Note that the shortest distance among the distances r1, r2, and r3 is rz.
And the remaining distances are rx and ry.

If the location information providing server 30 determines that the determination condition A is not satisfied, the location information providing server 30 uses the PHS method described below to calculate the distance from the base station.
The current coordinates P0 of the terminal 10 are calculated. That is, as shown in FIG. 3B, the position information providing server 30 uses the above-described equation (2) to cause the coordinate search engine 33 to use the distance r1 and the distance r between the base station CS1 and the base station CS2.
An intermediate coordinate P12 corresponding to the ratio of 2 and an intermediate coordinate P13 corresponding to the ratio of the distance r1 to the distance r3 between the base station CS1 and the base station CS3 are calculated. Further, the position information providing server 30 adds the base station CS12,
Assuming that CS13 exists, the coordinate search engine 33 calculates base station transmission power (electric field strength) CSP12, CSP13 of the assumed base stations CS12, CS13 located at the respective intermediate coordinates P12, P13 using the following formula.

CSP12 = r2 · CSP1 / (r1 + r2) + r1 · CSP2 / (r1 + r2) (4) CSP13 = r3 · CSP1 / (r1 + r3) + r1 · CSP2 / (r1 + r3) (5)

Further, the location information providing server 30 uses the average value of the received electric field strengths E1 and E2 as the base station CS12
, And the average value of the received electric field strengths E1 and E3 is used as the assumed received electric field strength E13 from the base station CS13, whereby the above-described calculation method in the case of two receivable base stations CSj is performed. Using PHS terminal 10
Can be accurately calculated.

On the other hand, the location information providing server 30
If it is determined that the determination condition A is satisfied, the PH is calculated using the “method of assuming the position of the center of gravity” described below.
The current coordinates P0 of the S terminal 10 are calculated. That is, the position information providing server 30 uses the coordinate search engine 33 to calculate the current coordinates P0 of the PHS terminal 10 using the following equation, that is, the equation for calculating the position of the center of gravity of the triangle.

P0 = (r1 + r2 + r3) / 3 (6)

When the PHS terminal 10 can receive three base stations CSj, the method of calculating the current coordinates P0 of the PHS terminal 10 is switched depending on whether the location information providing server 30 satisfies the determination condition A. ing. The reason will be described below with reference to FIG. As shown in FIG.
The current coordinates P0 of the S terminal 10 and each of the base stations CS1, CS2,
When the distances r1, r2, and r3 from the base station CS3 are substantially equal, the positional relationship between the base stations CS1, CS2, and CS3 becomes a substantially equilateral triangle, and the PHS terminal 10 is located substantially at the center of gravity of the equilateral triangle. Become. Therefore, in this case,
The current coordinates P0 of the PHS terminal 10 are determined by the respective base stations CS1, CS
2. Assuming that the position is the center of gravity of the triangle having CS3 as the vertex, it is not necessary to use the above-described “method of calculating from the distance ratio to the base station”, and it is possible to calculate PH by the formula for calculating the center of gravity.
The current coordinates P0 of the S terminal 10 can be easily calculated.

Further, in the above-mentioned "method of calculating from the distance ratio with the base station", the intermediate coordinates P12 corresponding to the ratio between the distances r1 and r2 and the intermediate coordinates P13 corresponding to the ratio between the distances r1 and r3 are calculated. , It is assumed that the current coordinate P0 of the PHS terminal 10 is present on the straight line L connecting the PHS terminal 10, and therefore, strictly, the straight line L may not pass through the actual current coordinate P0 of the PHS terminal 10 as shown in FIG. A relatively large error occurs in the current coordinates P0 calculated by the method. Therefore, when the distance between each of the base stations CS1, CS2, CS3 and the PHS terminal 10 is substantially the same value, the current coordinates P0 of the PHS terminal 10 calculated by the “method of assuming the position of the center of gravity”. Can reduce the error from the actual current coordinates compared to the current coordinates P0 calculated by the “method of calculating from the distance ratio to the base station”.
Then, the inventors obtained a simulation to obtain a range in which the accuracy of the current coordinates P0 of the PHS terminal 10 calculated by the “method of calculating assuming the position of the center of gravity” is within 100 [m]. That is, the distance excluding the shortest distance among the distances r1, r2, and r3 is within a range equal to or less than 2.5 times the shortest distance.

Therefore, the location information providing server 30 sets the PH
If the number of base stations CSj that the S terminal 10 can receive is three and the determination condition A is satisfied, the current coordinates P0 of the PHS terminal 10 are calculated by the “calculation method assuming the position of the center of gravity”. Thus, the current coordinates P0 of the PHS terminal 10 can be calculated simply and accurately.

Note that the location information providing server 30 uses the PHS
If the terminal 10 can receive only one base station CSj, for example, only the base station CS1, the coordinate search engine 33 acquires the distance r1 and the latitude / longitude coordinates P1 of the base station CS1, and then obtains the latitude / longitude coordinates P1. Is set as the current coordinate P0 of the PHS terminal 10.

As described above, in the location information providing system 1, the PHS terminal 1 is provided by the location information providing server 30.
When the current coordinate P0 of 0 is acquired, the position information providing server 3
The communication server 31 transmits the acquired current coordinates P0 to the PHS terminal 10 as position information DP by the communication server 31. Therefore, the PHS terminal 10
The current position can be displayed based on the received position information DP. As a result, the position information providing system 1 can easily and accurately calculate the current coordinates of the PHS terminal 10 and provide the PHS terminal 10 with accurate position information D.
P can be transmitted.

(2) Modifications (2-1) First Modification In the above-described embodiment, the present invention is applied to a position information providing system that provides information on the current coordinates P0 of the PHS terminal 10 to the terminal 10. However, the present invention is not limited to this. The present invention is not limited to this. Position information for providing position information via a facsimile or fixed telephone to a parent or the like within a predetermined reference range who wants to know the position of a child carrying a PHS terminal The present invention may be applied to a providing system. In this case, the PHS terminal 1
0 is sufficient if it has a function of collecting receivable base station information DCS in addition to the function of a normal PHS terminal, and does not need to have a function of displaying a current position. May be a dedicated terminal.

(2-2) Second Modification In the above-described embodiment, when the number of base stations CSj that can be received by the PHS terminal 10 is three, the “method of calculating assuming the position of the center of gravity” or “ The method of calculating the current coordinates P0 of the PHS terminal 10 by the "method of calculating from the distance ratio to the base station" has been described.
The current coordinates P of the PHS terminal 10 can be obtained by only one of the methods.
Even when 0 is calculated, the current coordinates of the PHS terminal 10 can be easily calculated with high accuracy compared to the related art.

(2-3) Third Modification In the above-described embodiment, only the information of the current coordinates P0 of the PHS terminal 10 is faxed or fixed to the PHS terminal 10 or a parent within a predetermined reference range. Although the case where the information is provided via the telephone has been described, the present invention is not limited to this, and map information including the current coordinates P0 may be provided, and other information such as shop information and sightseeing information around the current coordinates P0 may be provided. May be provided.

(2-4) Fourth Modification In the above-described embodiment, the case where the present invention is applied to the location information providing system using the PHS terminal has been described. Terminals and PHS
Generally, a PDA (Personal Digital Assembler) capable of communicating with a base station in a telephone system or a mobile telephone system.
The present invention can be widely applied to this type of portable terminal called istants).

[0034]

As described above, according to the present invention, the PHS
The position of a portable terminal such as a terminal can be easily and accurately calculated.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of a position information providing system according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a PHS terminal of the location information providing system.

FIG. 3A is a diagram for explaining a method of calculating current coordinates when the number of base stations that can receive the PHS terminal is two, and FIG. 3B is a diagram illustrating reception of the PHS terminal; FIG. 11 is a diagram provided for describing a method of calculating current coordinates when three possible base stations are provided.

FIG. 4 is a diagram for explaining switching of a current coordinate calculation method when the PHS terminal can receive three base stations;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Position information providing system, 10 ... PHS terminal, 30 ... Location information providing server, 31 ... Communication server, 32 ... Base station position information database, 33 ... Coordinate search engine.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5J062 AA08 BB05 CC18 FF01 5K067 AA33 AA42 BB04 BB36 DD19 DD43 DD44 EE02 EE10 EE24 HH22 HH23 HH24 JJ53 JJ54 JJ66 LL11

Claims (13)

[Claims] 1. A position calculating method for calculating a position of a mobile terminal communicating with a plurality of base stations, wherein at least one or a plurality of the base stations transmitting a signal received by the mobile terminal are specified. A specific information acquisition step of acquiring specific information to be performed from the signal; an electric field strength detection step of detecting a reception electric field strength of a signal transmitted from the base station specified by the specific information in the portable terminal; A distance calculating step of calculating a distance between the mobile terminal and the base station specified by the specific information, based on the base information specified by the specific information from the position information of the plurality of base stations stored in advance. Position information obtaining step of obtaining the position information of the station, if the number of base stations specified by the specific information is a plurality,
A position calculating step of calculating a position of the mobile terminal from the obtained position information of the plurality of base stations, based on a ratio of a distance between the calculated mobile terminal and the plurality of base stations specified by the specific information. A position calculation method characterized by the following. 2. The position calculation method according to claim 1, wherein in the position calculation step, when the number of base stations specified by the specific information is three,
It is determined whether or not the distance excluding the shortest distance among the distances between the calculated mobile terminal and the three base stations specified by the specific information is equal to or less than 2.5 times the shortest distance. 1. The distance excluding the distance is the shortest distance.
When the value is not more than five times, a position of the center of gravity or a predetermined range including the position of the center of gravity of a triangle having the obtained positions of the three base stations as vertices is calculated as the position of the portable terminal. . 3. The position calculation method according to claim 1, wherein, in the distance calculation step, a base station specified by the specific information from transmission power information of the plurality of base stations stored in advance. A position calculating step of obtaining transmission power information and calculating a distance between the mobile terminal and the base station specified by the specific information based on the obtained transmission power information and the detected received electric field strength. Method. 4. The position calculation method according to claim 1, further comprising a position display step of displaying the calculated position of the mobile terminal by the mobile terminal. 5. A position calculating device for calculating a position of an arbitrary portable terminal communicating with a plurality of base stations, wherein at least one or a plurality of the base stations transmitting a signal received by the portable terminal Information receiving means for receiving a signal including information of a received signal strength of a signal transmitted from the base station specified by the specific information in the mobile terminal, and information based on the received field strength A distance calculating unit that calculates a distance between the mobile terminal and each base station specified by the specific information; a position information holding unit that holds position information of all the base stations; and a position information holding unit that holds the position information. Position information obtaining means for obtaining the position information of the base station specified by the specific information from the specified position information; and when the number of base stations specified by the specific information is plural,
Position calculating means for calculating the position of the mobile terminal from the obtained position information of the plurality of base stations, based on a ratio of the distance between the calculated mobile terminal and the plurality of base stations specified by the specific information. A position calculating device characterized by the above-mentioned. 6. The position calculating device according to claim 5, wherein the position calculating means includes: when the number of base stations specified by the specific information is three,
It is determined whether or not the distance excluding the shortest distance among the distances between the calculated mobile terminal and the three base stations specified by the specific information is equal to or less than 2.5 times the shortest distance. 1. The distance excluding the distance is the shortest distance.
When the value is not more than five times, a position of the center of gravity or a predetermined range including the position of the center of gravity of the triangle having the obtained positions of the three base stations as vertices is calculated as the position of the portable terminal. . 7. The position calculating device according to claim 5, further comprising a power information holding unit that holds transmission power information of all the base stations, wherein the distance calculating unit includes: The transmission power information of the base station specified by the specific information is acquired from the held transmission power information, and the mobile terminal and the specific information are specified based on the obtained transmission power information and the received electric field strength. A position calculation device for calculating a distance from a base station. 8. The position calculating device according to claim 5, further comprising: a position transmitting unit configured to transmit a position signal including the calculated position of the mobile terminal to the mobile terminal. Calculation device. 9. The position calculation device according to claim 5, wherein a position of the PHS terminal as the portable terminal is calculated. 10. A mobile terminal that calculates its own position by communicating with a plurality of base stations, wherein the receiving unit receives a signal transmitted from the base station; Specific information obtaining means for obtaining, from the signal, specific information specifying at least one or a plurality of the base stations transmitting a signal; and detecting a received electric field strength of a signal transmitted from the base station specified by the specific information. Electric field strength detecting means; distance calculating means for calculating a distance between the portable terminal and the base station specified by the specific information based on the received electric field strength; and a position for holding position information of all the base stations. Information holding means, position information obtaining means for obtaining the position information of the base station specified by the specific information from the position information stored in the position information holding means, and a base specified by the specific information When the number of stations is two or more,
A position calculating unit that calculates a position of the mobile terminal from the obtained position information of the plurality of base stations, based on a ratio of the calculated distance between the mobile terminal and the plurality of base stations specified by the specific information. A mobile terminal characterized by the above-mentioned. 11. The mobile terminal according to claim 10, wherein the position calculating unit is configured to: when the number of base stations specified by the specific information is three,
Determining whether or not the calculated distance between the mobile terminal and the three base stations specified by the specific information, excluding the shortest distance, is equal to or less than 2.5 times the shortest distance; 1. The distance excluding the shortest distance is the shortest distance.
If the value is not more than five times, the mobile terminal calculates the position of the mobile terminal as a position of the mobile terminal, the barycentric position of a triangle having the obtained positions of the three base stations as vertices or a predetermined range including the barycentric position. 12. The mobile terminal according to claim 10, further comprising power information holding means for holding transmission power information of all the base stations, wherein the distance calculation means holds the power information in the power information holding means. The transmission power information of the base station specified by the specific information is obtained from the obtained transmission power information, and the mobile terminal is specified by the specific information based on the obtained transmission power information and the received electric field strength. A mobile terminal for calculating a distance from a base station. 13. The mobile terminal according to claim 10, wherein the mobile terminal is a PHS terminal.