JP3874201B2 - Terminal device and positioning method - Google Patents

Description

  The present invention relates to a terminal device and a positioning method.

2. Description of the Related Art Conventionally, a positioning system that measures the current position of a GPS receiver using, for example, a GPS (Global Positioning System), which is a satellite navigation system that uses a position information satellite, has been put into practical use. This GPS receiver grasps the signal frequency (received signal frequency) of the signal received from the GPS satellite based on the orbit information of the GPS satellite stored in advance, and the synchronization means of the GPS receiver It is configured to receive signals from GPS satellites by synchronizing with the received signal frequency.
However, for example, a crystal oscillator that constitutes a synchronization means of a GPS receiver fluctuates in frequency depending on the temperature (the frequency is shifted). Therefore, if any means is not taken, it can be quickly synchronized with the received signal frequency described above. It cannot be done, and it takes a long time for positioning.
On the other hand, the information indicating the frequency shift of the GPS receiver at the time of the previous positioning is held, and when the signal is received from the next GPS satellite, based on the information indicating the previous frequency shift, A technique for synchronizing with the received signal frequency has been proposed.
JP-A-5-256926 (FIG. 1 etc.)

  However, in the prior art, for example, when a long time has elapsed since the previous positioning and the temperature is different from the current, the frequency shift at the previous positioning is greatly different from the current frequency shift. Thus, there is a problem that the above-mentioned synchronization cannot be performed quickly, and it may take a long time to acquire a GPS satellite.

  Therefore, the present invention provides a terminal device and a positioning method capable of quickly capturing and positioning a position information satellite even when the frequency shift at the time of the previous positioning is greatly different from the current frequency shift. The purpose is to provide.

According to the first aspect of the present invention, there is provided a terminal device having positioning means for acquiring position-related information from a plurality of position information satellites and positioning a current position, for searching for the position information satellites. Search means, first acquisition target satellite determination means for determining a first acquisition target satellite from the plurality of position information satellites, and first acquisition for acquiring the first acquisition target satellite using the search means. Target satellite acquisition means, synchronization frequency information storage means for storing synchronization frequency information indicating a terminal side synchronization frequency for searching for each of the position information satellites, and the terminal side corresponding to the first acquisition target satellite First difference information acquisition means for acquiring first difference information indicating a difference between a synchronization frequency and a first acquisition frequency that is a frequency at which the first acquisition target satellite is acquired; and a second acquisition from the position information satellite Target satellite Second acquisition target satellite determination means for determining, second acquisition target satellite acquisition means for acquiring the second acquisition target satellite using all of the search means available, and the second acquisition target satellite Second difference information acquisition means for acquiring second difference information indicating a difference between the corresponding terminal-side synchronization frequency and a second acquisition frequency that is a frequency at which the second acquisition target satellite is acquired; and the first difference The terminal side corresponding to the second acquisition target satellite indicated in the second difference information and the difference between the terminal-side synchronization frequency corresponding to the first acquisition target satellite indicated in the information and the first acquisition frequency Positioning required number satellite capturing means for capturing the required number of positioning information satellites based on the first difference information or the second difference information when the difference between the synchronization frequency and the second capturing frequency is substantially equal. And have It is achieved by a terminal device, characterized in that.

In the satellite navigation system, in order to determine the current position by three-dimensional positioning, it is necessary to receive signals from, for example, four position information satellites.
However, for example, in order to capture four position information satellites, for example, if the twenty search means are equally divided and five search means try to capture each of the position information satellites, the terminal device For example, when the frequency shift of the GPS receiver is large, it is necessary for a long time.

In this regard, according to the configuration of the first invention, according to this point and the configuration of the first invention, the search means is used to capture the first capture target satellite. For example, one of the first acquisition target satellites is acquired by 20 search means. Therefore, the first acquisition target satellite can be acquired in a short time.
And if the said 1st acquisition object satellite is acquired, the said 1st acquisition frequency which is the frequency which the above-mentioned GPS receiver used for the acquisition will be known.
The first difference information indicates a shift between the terminal-side synchronization frequency corresponding to the first acquisition target satellite and the first acquisition frequency (hereinafter referred to as a synchronization frequency shift). The terminal-side synchronization frequency is different for each position information satellite because the orbits of the position information satellites are not the same, but the above-described synchronization frequency shift is due to a factor on the terminal device side. The position information satellites are common. Accordingly, it is possible to correct the shift of the synchronization frequency for each of the position information satellites based on the first difference information, and to quickly acquire and measure the second and subsequent position information satellites.
Accordingly, it is possible to provide a terminal device capable of quickly capturing and positioning a position information satellite even when a difference in synchronization frequency at the time of previous positioning is greatly different from a difference in current synchronization frequency. it can.
Furthermore, according to the configuration of the present invention, the second difference information is also used. Therefore, after verifying whether the above-described synchronization frequency shift indicated in the first difference information is accurate, the number of positioning required positions Information satellites can be captured. In addition, verifying the accuracy of the first difference information means that the accuracy of the second difference information is also verified at the same time. Then, the accuracy of the first acquisition frequency information is determined based on the difference between the terminal side synchronization frequency indicated in the first difference information and the first acquisition frequency, and the terminal side synchronization frequency indicated in the second difference information. It can be determined by whether or not the difference between the second acquisition frequencies is substantially equal.
Thereby, based on the first difference information or the second difference information whose accuracy has been verified, it is possible to quickly and surely capture and measure the position information satellite.

  According to a second aspect of the present invention, in the configuration of the first aspect of the invention, the first capturing target satellite capturing unit captures the first capturing target satellite using at least one search unit. Is a terminal device.

  According to a third aspect of the present invention, in the configuration of the first aspect of the invention, the first acquisition target satellite acquisition unit has a larger number of the search than the total number of the search units divided equally by the number of position information satellites necessary for positioning. The terminal device is configured to capture the first capture target satellite using means.

  According to the configuration of the third invention, for example, more search means (in this case, 4 or more) than the number obtained by equally dividing 20 that is the total number of the search means by 6 that is the number required for positioning. Thus, it is possible to capture one first supplementary satellite in a short time rather than capturing one position information satellite.

  A fourth invention is a terminal device according to any one of the first to third inventions, wherein the first difference information is information indicating a drift error of the terminal device.

  According to a fifth aspect of the present invention, in the configuration of any one of the first to fourth aspects, a positioning required number of satellites that capture position information satellites other than the first capture target satellite based on the first difference information. It is a terminal device characterized by having a capturing means.

  According to a sixth aspect of the present invention, in the configuration of the fifth aspect of the present invention, the positioning required number satellite capturing means is configured to capture a number of position information satellites necessary for positioning.

According to a seventh aspect of the present invention, in the configuration according to the fifth aspect or the sixth aspect of the present invention , the first acquisition unit that is necessary for tracking one of the position information satellites is used to acquire the first First acquisition target satellite tracking means for tracking the acquisition target satellite, and the required number of positioning satellite acquisition means uses the remaining search means excluding the tracking necessity search means to use the second acquisition target satellite. It is the terminal device characterized by catching.

The acquired first acquisition target satellite is preferably tracked in order to acquire information for positioning. For this purpose, the tracking necessity searching means is necessary.
On the other hand, the second acquisition target satellite can be acquired in a short time by acquiring as much of the search means as possible.
In this regard, according to the configuration of the seventh invention, since the second acquisition target satellite is acquired using the remaining search means excluding the tracking necessity search means, from the first acquisition target satellite, While making it possible to acquire information for positioning, it is possible to quickly acquire the second acquisition target satellite and acquire the second difference information.

In an eighth aspect based on any one of the fifth to seventh aspects, the positioning required number satellite capturing means tracks the first acquisition target satellite from all usable search means. The remaining search means excluding the tracking required search means required for tracking and the tracking required search means required for tracking the second acquisition target satellite are equally divided by the number of position information satellites required for positioning, etc. The terminal device is characterized in that the number of position information satellites necessary for positioning is acquired by using the remaining remaining search means.

In order to acquire information for positioning from not only the acquired first acquisition target satellite but also the acquired second acquisition target satellite, both the first acquisition target satellite and the second acquisition target satellite are used. It is desirable to keep track. For this purpose, search means for tracking the two position information satellites is necessary.
Then, by tracking the first acquisition target satellite and the second acquisition target satellite, the required number of positioning that needs to be newly acquired for positioning is one in the case of two-dimensional positioning, one in three dimensions In the case of positioning, two are sufficient, and for example, a total of three or four position information satellites, which is the number of position information satellites necessary for positioning, is short.
Further, since the accuracy of the above-mentioned synchronization frequency shift is verified by the first difference information and the second difference information, the third and subsequent position information satellites can be quickly captured even if there are few search means. it can.
For this reason, the acquisition of the third and subsequent position information satellites can be completed more quickly than the acquisition of the position information satellites one by one by simultaneously acquiring the position information satellites.

According to a ninth invention, in the configuration of the seventh invention or the eighth invention , when the first acquisition target satellite tracking means cannot track the first acquisition target satellite, the terminal device The terminal device is characterized in that the first acquisition target satellite is determined again.

In modern times, radio waves (electromagnetic waves) are overflowing with the development of various wireless systems.
For this reason, the terminal device is mistaken for having received a signal from the location information satellite even though it has received a signal other than the signal from the location information satellite (hereinafter referred to as an erroneous signal). It may be recognized. In the case of an erroneous signal, the first difference information is inaccurate and cannot be used for acquisition of other position information satellites.
In the case of this erroneous signal, since the position related signal that is included in the signal from the true position information satellite is not included, the terminal device cannot perform tracking after acquisition. For this reason, the said terminal device can recognize that it is a false signal.
According to the structure of 9th invention, in the case of an error signal, the said terminal device can determine the said 1st acquisition object satellite again, and can acquire the said 1st difference information from a true position information satellite.

According to the tenth aspect of the present invention, there is provided a terminal device having positioning means for acquiring position-related information from a plurality of position information satellites and positioning a current position. A first acquisition target satellite determination step for determining acquisition target satellites, and the terminal device uses a larger number of the search means than the total number of search means divided by the number of position information satellites necessary for positioning. A first acquisition target satellite acquisition step of acquiring the first acquisition target satellite; and the terminal device synchronization frequency information held by the terminal device for acquiring the position information satellites. a terminal side synchronizing frequency corresponding to the acquisition target satellite, and the first difference information obtaining step of obtaining first difference information indicating a difference between the first capturing frequency is captured frequency the first acquisition target satellites, the Terminal device A second acquisition target satellite determining step for determining a second acquisition target satellite from the plurality of position information satellites after execution of the first acquisition target satellite acquisition step; and all the search means that the terminal device can use. A second capture target satellite capturing step for capturing the second capture target satellite using the terminal, a terminal-side synchronization frequency corresponding to the second capture target satellite, and a frequency at which the second capture target satellite is captured. A second difference information acquisition step of acquiring second difference information indicating a difference from the second acquisition frequency, and the terminal device corresponds to the first acquisition target satellite indicated by the first difference information. The difference between the terminal-side synchronization frequency and the first acquisition frequency, and the difference between the terminal-side synchronization frequency corresponding to the first acquisition target satellite indicated in the second difference information and the second acquisition frequency are substantially equal. If have, on the basis of the first difference information or the second difference information, and the necessary-for-positioning satellite acquisition step of capturing a number of positioning information satellites required for positioning by a positioning method characterized by having a Achieved.

According to the configuration of the tenth aspect of the invention, even when the synchronization frequency shift at the time of the previous positioning is greatly different from the current synchronization frequency shift, the position information satellite can be quickly captured and positioned. .

According to an eleventh aspect of the invention, in the configuration of the tenth aspect of the invention, the terminal apparatus uses the tracking necessity search means necessary for tracking one of the position information satellites, and captures in the first acquisition target satellite acquisition step. A first acquisition target satellite tracking step for tracking the first acquisition target satellite, and performing the second acquisition target satellite acquisition step using the remaining search means excluding the tracking necessity search means. This is a characteristic positioning method.

According to the configuration of the eleventh aspect of the invention, it is possible to acquire information for positioning from the first acquisition target satellite, and quickly acquire the second acquisition target satellite to obtain the second difference. Information can be acquired.

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
The embodiments described below are preferred specific examples of the present invention, and thus various technically preferable limitations are given. However, the scope of the present invention is particularly limited in the following description. Unless otherwise stated, the present invention is not limited to these embodiments.

FIG. 1 is a schematic diagram showing a terminal 30 and the like according to an embodiment of the present invention.
As shown in FIG. 1, the terminal 30 is a positioning means for acquiring position-related information from a plurality of position information satellites such as GPS satellites 12a, 12b, 12c and 12d and positioning the current position. A GPS device 40 is included.
The GPS device 40 receives a position-related signal S1 from the GPS satellite 12a, receives a position-related signal S2 from the GPS satellite 12b, receives a position-related signal S3 from the GPS satellite 12c, and receives a position from the GPS satellite 12d. The related signal S4 is received.
The terminal 30 is, for example, a mobile phone, but may be a PHS (Personal Handy-phone System), a PDA (Personal Digital Assistance _), or the like.

(Main hardware configuration of terminal 30)
FIG. 2 is a schematic diagram showing the main hardware configuration of the terminal 30.
As illustrated in FIG. 2, the terminal 30 includes, for example, a computer. The computer includes a bus 32, and a CPU (Central Processing Unit) 34 and a storage device 36 are connected to the bus 32. The CPU 34 is a control unit that controls a storage device 36 and the like connected to the bus 32 in addition to processing a predetermined program. The storage device 36 is, for example, a RAM (Random Access Memory) or a ROM (Read Only Memory).

In addition, a communication device 42 for communicating via a base station (not shown) and a communication network is connected to the bus 32.
Further, the bus 32 is connected to a display device 44 for displaying various information.

Further, the above-described GPS device 40 is connected to the bus 32.
As shown in FIG. 2, the GPS device 40 includes, for example, a crystal oscillator 41 that is an oscillator that vibrates at a frequency that is a basis for generating a synchronization frequency for capturing a GPS satellite 12a or the like (see FIG. 1). .
The GPS device 40 includes, for example, search units 40a to 40t that are search means for searching for the GPS satellites 12a and the like. The search unit 40a and the like are configured to generate a synchronization frequency to be described later by modulating a frequency due to vibration of the crystal oscillator 41, and to search the GPS satellite 12a and the like using the synchronization frequency. That is, the search unit 40a and the like are configured so as to capture the GPS satellite 12a and the like by changing the synchronization frequency and synchronizing with the signal S1 and the like (see FIG. 1) from the GPS satellite 12a and the like.
The search units 40a to 40t are also used for tracking after capturing the GPS satellite 12a and the like.

The frequency search and the GPS satellite 12a search are used synonymously.
Each search unit 40a and the like can use one frequency at a time.
Therefore, for example, the GPS device 40 having a total of 20 search units 40a and the like can use 20 frequencies simultaneously. That is, the GPS device 40 can search for 20 GPS satellites 12a and the like at the same time.
Here, the number of frequencies that can be searched at one time is called search power. Since the GPS device 40 described above can search for 20 frequencies at a time, the search power is 20.
Here, a search method by the GPS device 40 will be described.

FIG. 3 is a conceptual diagram showing a search method for the GPS satellites 12a and the like.
In order to acquire a signal from the GPS satellite 12a or the like, the synchronization frequency on the GPS device 40 side must be matched to the frequency of each satellite, but the position of each satellite or the GPS device 40 varies relatively. The GPS device 40 receives the signal S1 transmitted from the GPS satellite 12a and the like due to the Doppler effect and the fluctuation in the frequency of the specification of the crystal oscillator 41 that creates the synchronization frequency on the GPS device 40 side. The frequency of each satellite may be different as described below.

  For example, a point H0 (see FIG. 3) on the straight line LH indicating the frequency indicates the frequency of the signal S1 transmitted from the GPS satellite 12a in FIG. The frequency of the signal S1 at the position of the GPS device 40 changes to H1 due to the Doppler effect DP.

However, the GPS device 40 does not necessarily recognize the signal S1 as a signal having the frequency H1.
This is because, as described above, the GPS device 40 recognizes the frequency of the signal S1 as SH1a due to the frequency shift generated by the GPS device 40 side. That is, the frequency SH1a is not a frequency at the position of the GPS device 40 but an apparent frequency recognized by the GPS device 40. In order for the GPS device 40 to search for the signal S1, it is necessary to synchronize with this apparent frequency SH1a. In other words, when the GPS device 40 captures the signal S1, it is synchronized with the apparent frequency SH1a. Therefore, the apparent frequency SH1a is also referred to as a capture frequency.
The above-described frequency shift on the GPS device 40 side is generally called drift. That is, the difference between the frequency H1 changed by the Doppler effect DP and the capture frequency SH1a is drift.
The change from the frequency H1 to the frequency SH1a (referred to as total drift) is due to a factor on the GPS device 40 side, but as shown in FIG. 3, this total drift is a shift in frequency estimated in advance. It includes an initial estimated drift D1 and a drift error D2. The detailed meaning of drift will be described later.

The GPS device 40 preliminarily estimates and holds information indicating the initial estimated drift D1 at the start of positioning, but cannot grasp the drift error D2, and has a frequency H2 considering the Doppler effect DP and the initial estimated drift D1. The search is started using as a synchronization frequency. The synchronization frequency is also called the initial search frequency.
The GPS device 40 executes the search sequentially by gradually changing the frequency around the synchronization frequency H2, such as the first search Sr1, the second search Sr2, and the third search Sr3. For example, the eighth search In Sr8, the frequency SH1a is captured and the GPS satellite 12a is captured.
Next, the above drift will be described in detail.

FIG. 4 is a conceptual diagram for explaining drift.
First, with reference to FIG. 4A, a description will be given of a time lag for the absolute time of the GPS satellite 12 a and the terminal 30 having the GPS device 40.

The specified frequency of the crystal oscillator 41 of FIG. 2 is, for example, H1 (for example, 27.456 × 10 ⁶ ) times in T1 seconds (1 second in absolute time) when the ambient temperature is 25 degrees Celsius (° C.). is there. That is, the specification frequency of the crystal oscillator 41 is H1 hertz (Hz). This means that the GPS device 40 recognizes that the H1 vibration of the crystal oscillator 41 corresponds to one second for the GPS device 40. As long as the crystal oscillator 41 maintains the specified frequency H1 Hertz, 1 second for the GPS device 40 is equal to 1 second of absolute time T1.

  However, the vibration performance of the crystal oscillator 41 varies depending on the ambient temperature. For example, as shown in FIG. 4A, the frequency is shifted by A (for example, 10) hertz (Hz), and is vibrated H1 times before T1 seconds elapse. There is a case. In this case, the crystal oscillator 41 vibrates H1 + A times (H11 times) in T1 seconds. That is, H11 vibrations correspond to T1 of 1 second in absolute time.

On the other hand, one second for the GPS device 40 has elapsed when the crystal oscillator 41 vibrates H1 times. This means that one second for the GPS device 40 is T2 which is H1 / H11 of the absolute time T1. As described above, assuming that H1 is 27.456 × 10 ⁶ and A is 10, T2 which is 1 second for the GPS device 40 is H1 / H11, so that it is 0.999999966 seconds in absolute time.

  As described above, since the time difference between the time on the GPS device 40 side and the absolute time is generated, as described below, there is also a time difference between the frequency of the signal at the position of the GPS device 40 and the frequency recognized by the GPS device.

Next, drift will be described with reference to FIG.
Although the frequency also changes due to the Doppler effect, what is described here is a frequency shift due to a factor on the crystal oscillator 41 side.
As shown in FIG. 4B, for example, the signal S1 from the GPS satellite 12a vibrates SH1 (for example, 1575.42 × 10 ⁶ ) times per second at the position of the terminal 30. That is, the signal S1 is SH1 hertz (Hz) at the position of the terminal 30.

However, the signal S1 vibrates only SH1 × T2 (for example, 1575.419426 × 10 ⁶ ) times at T2 which is one second for the GPS device 40 described with reference to FIG. That is, the signal S1 that vibrates SH1 times in the absolute time 1 second T1 vibrates only SH1 × T2 times in T2 that is 1 second for the GPS device 40.
That is, there is a deviation B between the frequency of the absolute time of the signal S1 at 1 second T1 and the frequency at 1 second T2 recognized by the GPS device 40.
This frequency shift B is generally called drift or drift amount.

In order for the GPS device 40 to search for the signal S1 and acquire the satellite 12a, the frequency SH1 × T2 at T2 per second recognized by the GPS device 40, not the frequency SH1 hertz (Hz) at the absolute time T1 of the signal S1. It is necessary to search for hertz (Hz) signals. That is, it is necessary to search for a signal having an apparent reception frequency SH1a.
The search for the signal of the apparent reception frequency SH1a is performed by the main hardware configuration of the terminal 30 described above and the main software configuration described below.

(Main software configuration of terminal 30)
FIG. 5 is a schematic diagram showing the main software configuration of the terminal 30.
As illustrated in FIG. 5, the terminal 30 includes a communication unit 102 corresponding to the communication device 42 in FIG. 2, a display unit 104 corresponding to the display device 44, and a positioning unit 106 corresponding to the GPS device 40.
The terminal 30 also includes a control unit 100 that controls each unit.

Furthermore, the terminal 30 includes a first storage unit 108 that stores various programs and a second storage unit 126 that stores various types of information.
As shown in FIG. 5, the first storage unit 108 stores a first acquisition target satellite determination program 110. The first acquisition target satellite determination program 110 is for the control unit 100 to determine the first GPS satellite (first acquisition target satellite) to be searched and acquired from among the GPS satellites 12a in FIG. Information. That is, the first acquisition target satellite determination program 110 and the control unit 100 are an example of a first acquisition target satellite determination unit that determines a first acquisition target satellite from a plurality of GPS satellites 12a and the like.

  Specifically, the control unit 100 calculates the elevation angle of each GPS satellite 12a and the like based on the approximate position information 128 and the satellite orbit information 130 stored in the second storage unit 126, and the signal strength is high. The GPS satellite that is estimated to be captured most quickly is determined as the first acquisition target satellite. The approximate position information 128 is information indicating the approximate position of the terminal 30, and is information indicating the positioning position at the previous positioning, for example. The satellite orbit information 130 is information indicating the orbit of the GPS satellite 12a and the like received from the GPS satellite 12a and held at the time of the previous positioning or the like.

The terminal 30 also has a first acquisition target satellite acquisition program 112 as shown in FIG. The first acquisition target satellite acquisition program 112 is information for the control unit 100 to acquire, for example, the GPS satellite 12a which is the first acquisition target satellite described above. The control unit 100 acquires the GPS satellite 12a using all of the usable search units 40a and the like according to the first acquisition target satellite acquisition program 112.
That is, the first acquisition target satellite acquisition program 112 and the control unit 100 use the first acquisition target satellite acquisition means for acquiring the first acquisition target satellite using all the search units 40a and the like that can be used (see FIG. 2). It is an example.

The terminal 30 also has a synchronization frequency information generation program 109 as shown in FIG.
The synchronization frequency information generation program 109 is configured such that the control unit 100 uses the frequency of the signal S1 and the like transmitted from each GPS satellite 12a, the Doppler effect DP (see FIG. 3) that differs for each GPS satellite 12a, and the like. This is information for generating the synchronization frequency information 132 based on the initial estimated drift D1 (see FIG. 3) common to 12a and the like.
The control unit 100 stores the generated synchronization frequency information 132 in the terminal second storage unit 126.

The synchronization frequency information 132 is information indicating a synchronization frequency for the control unit 100 to acquire the GPS satellite 12a and the like by the positioning unit 106. That is, the synchronization frequency information 132 is an example of synchronization frequency information indicating a terminal-side synchronization frequency for capturing the GPS satellite 12a and the like, and the second storage unit 126 is an example of a synchronization frequency storage unit.
As described above, the synchronization frequency is set based on the frequency at the time of transmission of the signal S1 or the like from each GPS satellite 12a or the like, the Doppler effect DP (see FIG. 3), and the initial estimated drift D1 (see FIG. 3).
Unlike the present embodiment, the synchronization frequency may be set based on only the frequency at the time of transmission of the signal S1 and the Doppler effect. That is, the frequency H1 in FIG. 3 may be set as the synchronization frequency.

6, 7 and 8 are diagrams showing an example of the search state.
FIG. 6 shows an example of a general search state for comparison with the search performed by the terminal 30.
That is, as shown in FIG. 6, the search units 40a to 40t of FIG. 2 are used as the GPS satellites 12a to 12t with reference to the synchronization frequencies (initial search frequencies) H2a to H2d for each GPS satellite 12a and the like shown in the synchronization frequency information 132. When searching for each of the GPS satellites 12a and the like, the time t required to acquire each GPS satellite 12a is four. The terminal 30 does not perform the search shown in FIG. 6 described here.

FIG. 7 shows an example of a state of search performed by the terminal 30.
As shown in FIG. 7, the control unit 100 of the terminal 30 is a GPS satellite that is estimated to be captured most rapidly based on the first acquisition target satellite determination program 110, for example, a GPS satellite 12 a as a first acquisition target. Based on the first acquisition target satellite acquisition program 112, the GPS satellite 12a is acquired using all the search units 40a and the like (see FIG. 2) that can be used. Since the search power is not distributed and all the search units 40a and the like are used to search for and acquire the GPS satellite 12a, the time t required to acquire the GPS satellite 12a is one.
At this time, the GPS satellite 12b other than the GPS satellite 12a is not searched.
The frequency when the positioning unit 106 searches for and acquires the GPS satellite 12a is referred to as a first acquisition frequency. This first acquisition frequency is not necessarily the same as the synchronization frequency indicated in the synchronization frequency information 132.

  As shown in FIG. 5, the terminal 30 has a first drift information generation program 114. The first drift information generation program 114 is information for the control unit 100 to generate difference information indicating a difference between the synchronization frequency corresponding to the GPS satellite 12a indicated in the synchronization frequency information 132 and the above-described first acquisition frequency. It is. That is, the first drift information generation program 114 and the control unit 100 acquire the first difference information indicating the difference between the above-described synchronization frequency and the first acquisition frequency that is the frequency at which the first acquisition target satellite is acquired. It is an example of 1 difference information acquisition means.

Specifically, the control unit 100 is a difference between the initial search frequency H2 of FIG. 7 that is the synchronization frequency indicated in the synchronization frequency information 132 and the first acquisition frequency SH1a based on the first drift information generation program 114. First drift information 134 (see FIG. 5) indicating the drift error D2 is generated.
And the produced | generated 1st drift information 134 is stored in the 2nd memory | storage part 126 of FIG.
As described above, the frequency shift D2 (see FIG. 8) between the synchronization frequency (initial search frequency) H2a (see FIG. 8) and the first acquisition frequency SH1a is called a drift error.

  Further, as shown in FIG. 5, the terminal 30 has a positioning required number satellite capturing program 124. The positioning necessary number satellite capturing program 124 is information for the control unit 100 to capture the necessary number of positioning satellites 12b and the like necessary for positioning based on the first drift information 134 indicating the drift error D2. . That is, the positioning required number satellite capturing program 124 and the control unit 100 are an example of the positioning required number satellite capturing unit that captures the required number of positioning information satellites necessary for positioning based on the first drift information 134 described above. .

Specifically, as shown in FIG. 8, the control unit 100 determines the required number of GPS satellites 12b necessary for positioning based on the first drift information 134 (see FIG. 5) indicating the drift error D2, as shown in FIG. Search using SH1b or the like as the synchronization frequency. That is, the initial initial search frequency H2b and the like of each GPS satellite 12b and the like are corrected based on the drift error D2 indicated in the first drift information 134, and a search is performed using the corrected new synchronization frequency.
The control unit 100 can calculate the Doppler effect of the signal from each GPS satellite 12b or the like based on the approximate position information 128 and the satellite orbit information 130 of FIG. Since the first drift information 134 is information on the GPS device 40 side, it is commonly used for searching for the GPS satellites 12b other than the GPS satellites 12a. For this reason, the search for the GPS satellites 12b and the like can be started based on the synchronization frequency SH1b and the like (see FIG. 8) estimated as the frequency at the position of the terminal 30 such as the signal S2 from the GPS satellites 12b and the like. As described above, the first drift information 134 is accurate because it is information obtained by actual measurement, and the synchronization frequency SH1b and the like set based on the first drift information 134 are very close to the frequency actually received. For this reason, acquisition of the GPS satellite 12b and the like can be completed quickly even if the search power is distributed.
That is, for example, the time t is 1 for capturing the GPS satellite 12b and the like. As a result, if the time t for capturing the first capture target satellite 12a is 1, the time t required for capturing the other GPS satellites 12b and the like is two.

(About operation example of terminal 30 of the present embodiment)
Although the terminal 30 is configured as described above, an example of its operation will be described below.
FIG. 9 is a schematic flowchart showing an operation example of the terminal 30.
In step ST1, the terminal 30 in FIG. 1 determines, for example, the GPS satellite 12a, which is estimated to be captured most quickly among the GPS satellites 12a and the like, based on the approximate position information 128 and the satellite orbit information 130 in FIG. 1 to be captured.
That is, step ST1 is an example of a first acquisition target satellite determination step in which the terminal 30 determines a first acquisition target satellite from a plurality of GPS satellites 12a and the like.

Subsequently, the terminal 30 starts a process of acquiring the GPS satellite 12a, which is the first acquisition target satellite, by searching using all search powers (step ST2).
That is, step ST2 is an example of a first capture target satellite capturing step in which the terminal 30 captures the first supplemental target satellite using all available search means.
In step ST2, as shown in FIG. 7, for example, it is generated based on the initial estimated drift D1 that is the drift at the time of the previous positioning and the Doppler effect DP, and is stored in the second storage unit in FIG. 5 as an example of the synchronization frequency information 132. The search is started with the frequency H2 being set as the initial search frequency.

Subsequently, the terminal 30 determines whether or not the GPS satellite 12a that is the first acquisition target satellite has been acquired (step ST3), and if it has been acquired, estimates the first drift error D2 (see FIG. 7) ( Step ST4), the first drift error D2 is determined (step ST5).
That is, in step ST4, the first drift information indicating the difference between the terminal-side synchronization frequency corresponding to the first acquisition target satellite and the first acquisition frequency that is the frequency at which the terminal 30 has acquired the first acquisition target satellite. It is an example of the 1st difference information acquisition step which acquires 134 (1st difference information).
The control unit 100 estimates the first drift error D2 as a difference between the initial search frequency that is the synchronization frequency and the frequency at which the GPS satellite 12a is captured.

  Subsequently, the terminal 30 tracks the GPS satellite 12a, which is the first acquisition target satellite, using the tracking search power (step ST6). The search power for tracking uses a part of search power, for example, four search units 40a in FIG.

In parallel with step ST6, the terminal 30 acquires the required number of positioning satellites (step ST7). At this time, the first difference information described above is used.
That is, step ST7 is an example of a positioning required number satellite capturing step in which the terminal 30 captures the necessary number of positioning information satellites necessary for positioning based on the first difference information.
In the case of three-dimensional positioning, four or more GPS satellites 12a and the like are necessary for positioning.
In step ST6, since the GPS satellite 12a has been tracked, three or more GPS satellites 12b are newly required for positioning. Since the GPS satellite 12b and the like use a new synchronization frequency SH1b and the like obtained by correcting the initial search frequency H2b and the like by the first difference information as shown in FIG. 8, the GPS satellite 12b and the like can be quickly captured.

  Note that, unlike the present embodiment, the terminal 30 receives signals from the GSP satellites 12a and the like that are more than the required number of positioning, and then selects the GPS satellites 12a and the like with a small positioning error, and performs positioning. Good.

If the positioning is successful (step ST8), the terminal 30 calculates the current position (step ST9), displays the current position on the display unit 104 of FIG. 5, and ends.
As described above, since the terminal 30 captures the first acquisition target satellite, for example, the GPS satellite 12a using all the search means that can be used, the terminal 30 takes less time than when the search power is distributed. One GPS satellite 12a can be acquired.
Then, when the GPS satellite 12a is captured, the first capture frequency that is the frequency used by the GPS receiver 40 for capturing is known. Based on the first difference information indicating the difference between the first acquisition frequency and the terminal-side synchronization frequency, the number of positioning required satellites (for example, three in addition to the GPS satellite 12a) is acquired.
Since the first difference information indicates a synchronization frequency shift (drift error), the synchronization frequency shift is corrected based on the first difference information, and the second and subsequent GPS satellites 12b and the like can be quickly detected. Capturing and positioning can be performed.
Thereby, even if the shift of the synchronization frequency at the time of the previous positioning is greatly different from the shift of the current synchronization frequency, the GPS satellite 12a and the like can be quickly captured and positioned.

  Further, since the terminal 30 does not need to provide data indicating the relationship between the drift amount and temperature peculiar to each crystal oscillator and a circuit for measuring the temperature, the terminal 30 can be reduced in size and cost.

(Second Embodiment)
Next, a second embodiment will be described.
Since the configuration of the terminal 31 in the second embodiment is similar to that of the terminal 30 in the first embodiment, common portions are denoted by the same reference numerals, and the description thereof is omitted. The explanation will be focused on.

FIG. 10 is a schematic diagram showing a main software configuration and the like of the terminal 31 according to the second embodiment.
As shown in FIG. 10, in the second embodiment, unlike the first embodiment, the first storage unit 108 of the terminal 31 stores the second acquisition target satellite determination program 116, the second acquisition target satellite. An acquisition program 118, a second drift information generation program 120, and a drift estimation value determination program 122 are stored.

The second acquisition target satellite determination program 116 is information for the control unit 100 to determine the second acquisition target satellite. That is, the second acquisition target satellite determination program 116 and the control unit 100 are an example of a second acquisition target satellite determination unit that determines the second acquisition target satellite from the GPS satellites 12a and the like.
Based on the second acquisition target satellite determination program 116, the control unit 100 selects the second acquisition target satellite based on the GPS satellite that is estimated to be quickly acquired based on the approximate position information 128 and the satellite orbit information 130 in FIG. 10. Determine as.

The second acquisition target satellite acquisition program 116 is information for the control unit 100 to acquire the second acquisition target satellite by the positioning unit 106. That is, the second acquisition target satellite acquisition program 116, the control unit 100, and the positioning unit 106 are examples of the second acquisition target satellite acquisition unit that acquires the second supplementary target satellite using all available search units. It is.
Here, for example, five search units 40a to 40e shown in FIG. 2 are used for tracking the first acquisition target satellite, for example, the GPS satellite 12a. Therefore, all the search powers that can be used to acquire the second acquisition target satellite, for example, the GPS satellite 12b, are 15 search units 40f to 40t. The GPS satellite 12b can be quickly acquired by searching the GPS satellite 12b which is the second acquisition target satellite with the 15 search powers without searching for the other GPS satellites 12c and the like.
That is, according to the positioning required number satellite acquisition program 124, the control unit 100 searches the second acquisition target satellite by the positioning unit 106 using the remaining search means excluding the tracking required search power.
The positioning unit 106 that tracks the GPS satellite 12a that is the first acquisition target satellite is an example of a first acquisition satellite tracking unit.
Here, the frequency when the positioning unit 106 searches and acquires the GPS satellite 12b is referred to as a second acquisition frequency. This second acquisition frequency is not necessarily the same as the synchronization frequency indicated in the synchronization frequency information 132. Moreover, it is not necessarily the same as the first acquisition frequency described above.

The second drift information generation program 120 is information for the control unit 100 to generate difference information indicating a difference between the synchronization frequency indicated in the synchronization frequency information 132 and the above-described second acquisition frequency. That is, the second drift information generation program 120 and the control unit 100 have second difference information indicating a difference between a synchronization frequency corresponding to the GPS satellite 12b and a second acquisition frequency that is a frequency at which the second acquisition target satellite is acquired. It is an example of the 2nd difference information acquisition means to acquire.
The specific content of the second drift information generation program 120 is the same as that of the first drift information generation program 114 described above.
The control unit 100 stores the generated second drift information 136 in the second storage unit 126 of FIG.

  The second drift estimated value determination program 122 is information for the control unit 100 to determine a drift estimated value. Based on the drift estimation value determined by the drift estimation value determination program 122, the control unit 100 captures by searching the number of GPS satellites 12c and the like necessary for positioning by the positioning necessary number satellite capturing program 124 of FIG. . That is, unlike the first embodiment, the positioning required number satellite capturing program 124, which is an example of the positioning required number satellite capturing means, and the control unit 100 include the first drift information 134 (first difference information) and the second drift. Based on the information 136 (second difference information), the required number of GPS satellites 12c and the like are captured.

  Specifically, when the drift error indicated by the first drift information 134 in FIG. 10 is substantially equal to the drift error indicated by the second drift information 136 based on the drift estimated value determination program 122, the control unit 100 It is determined that the first drift information 134 (or the second drift information 136) is accurate, and based on the first drift information 134 or the second drift information 136, the number of GPS satellites 12c and the like necessary for positioning are determined. It is captured by search.

Here, the case where the drift error indicated by the first drift information 134 in FIG. 10 is substantially equal to the drift error indicated by the second drift information 136 is as follows.
That is, for example, drift that is predicted to vary in 10 seconds from when the first drift information 134 is generated to when the second drift information 136 is generated is referred to as drift variation. The maximum value of the inevitably drift fluctuation can be predicted based on the amount of heat generated by the terminal 31 itself, the temperature characteristic of the crystal oscillator 41, and the like. The difference between the drift error indicated by the first drift information 134 and the drift error indicated by the second drift information 136 (hereinafter referred to as the drift difference) is inevitably the maximum value of drift fluctuation, for example, 40 Hz (Hz ), The drift error indicated by the first drift information 134 and the drift error indicated by the second drift information 136 may be regarded as substantially equal. The maximum value of the inevitable drift of 40 hertz (Hz) is an example of an experimentally obtained value.

By the way, for example, the search Sr1 shown in FIG. 7 is performed at a predetermined frequency interval (search step), for example, 50 Hz (Hertz) interval.
Therefore, the minimum value of the drift difference that can be detected by the terminal 31 is the search step unit even if the above-mentioned inevitably drift fluctuation is very small.

Therefore, the control unit 100 of the terminal 31 determines that the drift difference is equal to or smaller than the larger one of the maximum value of the drift fluctuation and the search step, and the drift error indicated by the first drift information 134 and the second drift information 136. It is determined that the drift errors shown in FIG.
In other words, if the maximum value of the drift fluctuation is, for example, 40 hertz (Hz) and the search step is, for example, 50 Hz (hertz), the drift information is within 50 hertz (Hz), and the first drift information It is determined that the drift error indicated by 134 and the drift error indicated by the second drift information 136 are substantially equal.

  Unlike the present embodiment, the drift error indicated by the first drift information 134 is not necessarily compared with the maximum drift fluctuation value and the search step, and if the drift difference is necessarily within the drift fluctuation or within the search step, The drift error indicated by the second drift information 136 may be determined to be substantially equal.

  When the control unit 100 determines that the drift error indicated by the first drift information 134 and the drift error indicated by the second drift information 136 are substantially equal by the method described above, the first drift information 134 or the first drift information 134 The 2 drift information 136 is stored in the second storage unit 126 as the drift estimated value information 138.

The drift estimated value information 138 is used to capture the GPS satellites 12c and the like necessary for positioning.
In the case of three-dimensional positioning, it is necessary to receive signals from four or more GPS satellites in total, but the positioning unit 106 in FIG. 10 tracks the GPS satellite 12a and GPS satellite 12b as they are because they have been captured. To do. Therefore, the number of GPS satellites necessary for positioning is two in addition to the GPS satellites 12a and 12b.
As described above, for tracking, for example, five search units 40a (see FIG. 2) are used for one GPS satellite. For tracking two GPS satellites 12a and 12b, for example, ten search units 40a to 40j are used. Then, the remaining search power is obtained by excluding 10 used for tracking of the GPS satellite 12a and the GPS satellite 12b from a total of 20 search units 40a and the like included in the GPS device 40 of FIG. Ten search units 40k to 40t are equally used for two GPS satellites to search for and capture two GPS satellites, for example, GPS satellite 12c and GPS satellite 12d.
That is, the control unit 100 in FIG. 10 determines the search unit and the second search unit necessary for tracking the first acquisition target satellite from all the search units 40a and the like that can be used based on the positioning required number satellite acquisition program 124. Using the remaining search means that equally divides the remaining search unit 40k, etc., excluding the search unit necessary for tracking the acquisition target satellite, by the required number of positioning, each position information satellite of the required number of positioning is captured. To do.

As described above, since the terminal 31 also uses the second drift information 136 (second difference information), the above-described synchronization frequency shift (drift error) indicated by the first drift information 134 (first difference information) is increased. After verifying the accuracy, the required number of positioning satellites 12c and the like can be captured. In addition, verifying the accuracy of the first difference information means that the accuracy of the second difference information is also verified at the same time.
Thereby, based on the 1st difference information or 2nd difference information by which the accuracy was verified, the GPS satellite 12c etc. can be rapidly captured and measured.

When the positioning unit 106 cannot track the first acquisition target satellite, for example, the GPS satellite 12a, the terminal 31 determines the first acquisition target satellite again.
This is because, in modern times, radio waves (electromagnetic waves) are overflowing with the development of various wireless systems, so the terminal 31 receives signals other than signals from the GPS satellites 12a and the like (referred to as false signals). Nevertheless, there is a case where it is mistakenly recognized as a signal received from the GPS satellite 12a or the like. In the case of an erroneous signal, the first difference information is inaccurate and cannot be used for capturing other GPS satellites 12c and the like.
In the case of this erroneous signal, the position-related signal carried on the signal from the true GPS satellite 12a or the like is not on board, so the terminal 31 cannot perform tracking after capture. For this reason, the terminal 31 can recognize that it is an erroneous signal.
Therefore, in the case of an erroneous signal, the terminal 31 determines the first acquisition target satellite again, whereby the first difference information from the true GPS satellite 12a or the like can be acquired.

(Regarding an operation example of the terminal 31 of the present embodiment)
Although the terminal 31 is configured as described above, an example of its operation will be described below.
11, FIG. 12, FIG. 13 and FIG. 14 are schematic flowcharts showing an operation example of the terminal 31.
Similarly to the terminal 30 of the first embodiment, the terminal 31 determines the first drift error through steps ST1 to ST5 in FIG. Specifically, the control unit 100 in FIG. 10 captures, for example, the GPS satellite 12a (step ST1) determined as the first acquisition target satellite using all search powers (step ST2), and captures the same. Is successful (step ST3), the first drift error is estimated (step ST4), and the first drift error shown as the drift error D2 in FIG. 8 is determined (step ST5). Then, as shown in FIG. 10, the first drift error is stored in the second storage unit 126 as the first drift information 134.

Subsequently, the terminal 31 tracks the GPS satellite 12a using the tracking search power (step ST6). If the tracking fails (step ST61), the terminal 31 deletes the first drift error from the second storage unit 126. (Step ST62), the first acquisition target satellite is changed (step ST63). That is, if the terminal 31 cannot track the first acquisition target satellite in step ST61, the terminal 31 executes the first acquisition target satellite acquisition step (step ST2) again.
The above-described step ST6 is an example of a first acquisition target satellite tracking step in which the terminal 31 tracks the first acquisition target satellite using the tracking necessity search means necessary for tracking one GPS satellite. .

When the terminal 31 determines the first drift error in step ST5 of FIG. 11 described above, the terminal 31 executes step ST21 and subsequent steps in FIG. 12 in parallel with step ST6 and subsequent steps in FIG.
That is, in step ST21, the control unit 100 in FIG. 10 determines the second acquisition target satellite as, for example, the GPS satellite 12b in FIG. 1, and acquires the GPS satellite 12b using all the available search powers. When the acquisition is completed (step ST22) and the capture is completed (step ST23), the second drift error is estimated (step ST24), and the second drift error is determined (step ST25). The control unit 100 stores the generated second drift error in the second storage unit 126 as the second drift information 136.
Step ST21 described above is an example of a second acquisition target satellite determination step in which the terminal 31 determines a second acquisition target satellite from the plurality of GPS satellites 12b and the like after the execution of the first acquisition target satellite acquisition step (step ST2). It is. In addition, although the terminal 31 of this Embodiment performs step ST21 after step ST5, unlike this embodiment, if it is after step ST2, it may not be restricted after step ST5.

The above-described step ST22 is an example of a second acquisition target satellite acquisition step in which the terminal 31 acquires, for example, the GPS satellite 12b, which is the second acquisition target satellite, using all available search means. Here, all search means that can be used are search powers excluding the tracking search power necessary for tracking the GPS satellite 12a that is the first acquisition target satellite.
Step ST24 acquires the second difference information indicating the difference between the initial search frequency H2 of FIG. 8 that is the terminal side synchronization frequency and the second acquisition frequency that is the frequency at which the second acquisition target satellite is acquired. It is an example of an information acquisition step.

  Subsequently, the terminal 31 tracks the GPS satellite 12b (step ST26). If the tracking is not successful (step ST27), the terminal 31 deletes the second drift information 136 stored in the storage unit 126 (step ST28). Is changed (step ST29), and step ST22 is executed again.

When terminal 31 determines that the first drift error and the second drift error have been determined in step ST5 of FIG. 11 and step ST25 of FIG. 12 described above (step ST31 of FIG. 13), the first drift is determined. It is determined whether or not the first drift error indicated by the information 134 and the second drift error indicated by the second degree lift information 136 are substantially equal (step ST32 in FIG. 13), and the first drift error and the second drift error are determined. If the drift errors are substantially equal, the first drift error or the second drift error is determined as the drift estimation value (step ST33). The control unit 100 stores the determined drift estimation value in the second storage unit 126 as drift estimation value information 134.
And the control part 100 performs step ST41 and subsequent of FIG. 14 using this drift estimated value information 134. FIG.

In step ST41, for example, the terminal 31 determines that two GPS satellites are necessary in addition to the already-acquired GPS satellites 21a and 12b for the three-dimensional positioning. The GPS satellite 12c is determined, and the fourth acquisition target satellite is determined, for example, as the GPS satellite 12d.
Then, the terminal 31 equally divides the available search power by 2 that is the number of acquisition target satellites (step ST42), and the GPS satellite 12c that is the third acquisition target satellite and the GPS satellite that is the fourth acquisition target satellite. This is acquired by searching for 12d (step ST43).
If the positioning is successful (step ST44), the terminal 31 calculates the current position (step ST45), and displays the current position on the display unit in FIG.

As described above, when the drift error indicated in the first difference information is substantially equal to the drift error indicated in the second difference information, the terminal 31 is based on the first difference information or the second difference information. The required number of positioning satellites 12c and the like are captured.
That is, by using the second difference information, it is possible to capture the required number of positioning GPS satellites 12c and the like after verifying whether the first difference information is accurate. Based on the difference information or the second difference information, the GPS satellite 12c and the like can be quickly captured and measured.

  Note that, unlike the present embodiment, the terminal 31 receives signals from the GSP satellites 12a and the like that are more than the required number of positioning, and then selects the GPS satellites 12a and the like with a small positioning error and performs positioning. Good.

(About programs and computer-readable recording media)
In the computer, the first acquisition target satellite determination step, the first acquisition target satellite acquisition step, the first difference information acquisition step, the second acquisition target satellite determination step, and the second acquisition target satellite acquisition step of the above-described operation example, The terminal apparatus control program for executing the second difference information acquisition step, the positioning required number satellite acquisition step, and the like.
Moreover, it can also be set as the computer-readable recording medium etc. which recorded the control program etc. of such a terminal device.

  A program storage medium used for installing the control program of the terminal device in the computer and making it executable by the computer is, for example, a flexible disk such as a floppy (registered trademark), a CD-ROM (Compact Disc Read Only). Semiconductor memory in which programs are temporarily or permanently stored as well as package media such as Memory, CD-R (Compact Disc-Recordable), CD-RW (Compact Disc-Rewriterable), DVD (Digital Versatile Disc), etc. It can be realized with a magnetic disk or a magneto-optical disk.

  The present invention is not limited to the embodiments described above. Furthermore, the above-described embodiments may be combined with each other.

It is the schematic which shows the terminal etc. which are embodiment of this invention. It is the schematic which shows the main hardware constitutions of a terminal. It is a conceptual diagram which shows the search method of a GPS satellite. It is a conceptual diagram for demonstrating a drift. It is the schematic which shows the main software structures etc. of a terminal. It is a figure which shows an example of a search state. It is a figure which shows an example of a search state. It is a figure which shows an example of a search state. It is a schematic flowchart which shows the operation example of a terminal. It is the schematic which shows the main software structures etc. of a terminal. It is a schematic flowchart which shows the operation example of a terminal. It is a schematic flowchart which shows the operation example of a terminal. It is a schematic flowchart which shows the operation example of a terminal. It is a schematic flowchart which shows the operation example of a terminal.

Explanation of symbols

  12a, 12b, 12c, 12d ... GPS satellite, 30 ... terminal, 34 ... CPU, 36 ... storage device, 38 ... input device, 40 ... GPS device, 40a to 40t. ..Search unit 42... Communication device 44. Display device 100. Control unit 102. Communication unit 104. Display unit 106. Positioning unit 108. -1st memory | storage part, 110 ... 1st acquisition object satellite determination program, 114 ... 1st drift information generation program, 116 ... 2nd acquisition object satellite determination program, 120 ... 2nd drift information generation Program 122 ... drift estimation value determination program 124 ... positioning required number satellite acquisition program 126 ... second storage unit 128 ... approximate position information 130 ... satellite orbit information 132 And synchronization frequency information

Claims (11)

A terminal device having positioning means for acquiring position-related information from a plurality of position information satellites and positioning a current position,
Search means for searching for the position information satellite;
First acquisition target satellite determining means for determining a first acquisition target satellite from the plurality of position information satellites;
First capture target satellite capturing means for capturing the first capture target satellite using the search means;
Synchronization frequency information storage means for storing synchronization frequency information indicating a terminal-side synchronization frequency for searching for each of the position information satellites;
1st difference information which acquires the 1st difference information which shows the difference of the 1st acquisition frequency which is the frequency which acquired the 1st acquisition object satellite and the terminal side synchronous frequency corresponding to the 1st acquisition object satellite Acquisition means;
Second acquisition target satellite determining means for determining a second acquisition target satellite from the position information satellite;
Second acquisition target satellite acquisition means for acquiring the second acquisition target satellite using all of the available search means;
Second difference information for acquiring second difference information indicating a difference between the terminal-side synchronization frequency corresponding to the second acquisition target satellite and a second acquisition frequency that is a frequency at which the second acquisition target satellite is acquired. Acquisition means;
Corresponds to the difference between the terminal-side synchronization frequency corresponding to the first acquisition target satellite indicated in the first difference information and the first acquisition frequency, and the second acquisition target satellite indicated in the second difference information. If the difference between the terminal-side synchronization frequency and the second acquisition frequency is substantially equal, positioning is required to acquire the required number of position information satellites based on the first difference information or the second difference information. Several satellite acquisition means,
The terminal device characterized by having.   The terminal device according to claim 1, wherein the first acquisition target satellite acquisition unit is configured to acquire the first acquisition target satellite using at least one of the search units.   The first capturing target satellite capturing unit captures the first capturing target satellite by using a larger number of the searching units than the total number of the searching units divided by the number of position information satellites necessary for positioning. The terminal device according to claim 1, wherein the terminal device is configured as follows.   The terminal device according to claim 1, wherein the first difference information is information indicating a drift error of the terminal device.   5. The satellite according to claim 1, further comprising a positioning required number satellite capturing unit configured to capture a position information satellite other than the first capture target satellite based on the first difference information. Terminal device.   6. The terminal device according to claim 5, wherein the positioning necessary number satellite capturing unit is configured to capture a number of position information satellites necessary for positioning. First tracking target satellite tracking means for tracking the captured first capture target satellite using tracking required search means necessary for tracking the one position information satellite;
Wherein the necessary-for-positioning satellite acquisition means, claim 5 or claim 6, characterized in that capturing the using the remaining searching means excluding the tracking needs searcher second target satellite The terminal device described in 1. The required number of positioning satellite acquisition means is necessary for tracking the tracking necessity search means and the second acquisition target satellite necessary for tracking the first acquisition target satellite from all usable search means. The remaining search means other than the tracking-required search means are equally divided by the number of position information satellites necessary for positioning, and the number of position information satellites required for positioning is captured. The terminal device according to claim 5 , wherein the terminal device is a terminal device. The said terminal device determines the said 1st capture object satellite again, when the said 1st capture object satellite tracking means cannot track the said 1st capture object satellite, The said 7th capture object satellite is characterized by the above-mentioned. Item 9. The terminal device according to any one of Items 8 to 8 . A terminal apparatus having positioning means for acquiring position-related information from a plurality of position information satellites and positioning a current position determines a first acquisition target satellite from the plurality of position information satellites. Steps,
A first capture target satellite that captures the first capture target satellite by using a larger number of the search means than the terminal device equally divides the total number of search means by the number of position information satellites necessary for positioning. A capture step;
The terminal-side synchronization frequency corresponding to the first acquisition-target satellite indicated in the terminal-side synchronization frequency information held by the terminal device for acquiring each of the position information satellites, and the first acquisition-target satellite A first difference information acquisition step of acquiring first difference information indicating a difference from a first acquisition frequency that is a frequency at which
A second acquisition target satellite determining step in which the terminal device determines a second acquisition target satellite from the plurality of position information satellites after the execution of the first acquisition target satellite acquisition step;
A second capture target satellite capturing step in which the terminal device captures the second capture target satellite using all of the available search means;
Second difference information acquisition for acquiring second difference information indicating a difference between a terminal-side synchronization frequency corresponding to the second acquisition target satellite and a second acquisition frequency that is a frequency at which the second acquisition target satellite is acquired. Steps,
The terminal device has a difference between the terminal-side synchronization frequency corresponding to the first acquisition target satellite indicated by the first difference information and the first acquisition frequency, and the first difference indicated by the second difference information. When the terminal-side synchronization frequency corresponding to the acquisition target satellite and the difference between the second acquisition frequencies are substantially equal, the number of pieces of position information necessary for positioning based on the first difference information or the second difference information Said positioning required number of satellite acquisition steps for acquiring satellites;
A positioning method characterized by comprising: A first acquisition in which the terminal device tracks the first acquisition target satellite acquired in the first acquisition target satellite acquisition step by using tracking necessity search means necessary for tracking the one position information satellite. A target satellite tracking step,
11. The positioning method according to claim 10, wherein the second acquisition target satellite acquisition step is executed using the remaining search means excluding the tracking necessity search means.

Images