JP2008002861A - Apparatus and method for position detection - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely receive GPS signals from satellites and detect current positions without unnecessary consumption of electric power or the occurrence of a substantial voltage drop in cells to bring apparatuses to a breakdown, when using coin cells and other compact cells as power supplies. <P>SOLUTION: In a CPU 31, an RF control part 34 controls with respect to an RF part 2 to change over from a non-operating mode to an operating mode and from an operating mode to a non-operating mode; when none of five items of subframe data has been acquired, change-over from a non-operating mode to an operating mode is made intermittently in matching with the transmission of subframe data which has not been acquired; and when all the five pieces of subframe data have been acquired, a current position is computed, on the basis of positional information included in the subframe data. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a position detection apparatus and a position detection method, and more particularly to a position detection apparatus and a position detection method for receiving a radio wave from a satellite and detecting a current position.

  A GPS (Global Positioning System) is a system that receives radio waves from a plurality of satellites and detects a current position. The satellites in this case are not geostationary satellites, but 32 satellites that orbit the altitude of 20,000 km and change their positions with respect to the earth. In order to detect the current position, it is necessary to receive GPS signals from at least three of the 32 satellites. Actually, GPS signals are received from four satellites to detect the current position. A 30-second mainframe is transmitted from each satellite. This main frame is composed of 5 subframes each having 6 seconds, and each subframe is composed of 300-bit data. Among the first to fifth subframes, the first subframe includes the state and clock correction coefficient of each satellite, and the second and third subframes include orbit information of each satellite. “Ephemeris” is stored, and “almanac”, which is general orbit information common to all 32 satellites, is stored in the fourth and fifth subframes. FIG. 7 is a block diagram showing a configuration of a conventional position detecting device using a wristwatch. As shown in FIG. 7, the position detection device includes an antenna 11, an RF unit 12, a baseband processing unit 13, a system 14, and a power supply 15.

  The antenna 11 receives a GPS signal from a satellite and inputs it to the RF unit 12. The RF unit 12 demodulates the input GPS signal and inputs the baseband signal to the baseband processing unit 13. The baseband processing unit 13 includes a CPU 131, n search engines 132, and a synchronization detection unit 133. The synchronization detection unit 133 detects an 8-bit synchronization signal (referred to as “preamble”) at the head of each subframe, and inputs the start timing of the subframe to the CPU 131. The CPU 131 activates n search engines 132 based on the preamble from the synchronization detection unit 133. Each search engine takes one subframe and stores the data. Therefore, when receiving GPS signals from four satellites and detecting the current position, the data of five consecutive subframes transmitted simultaneously from each satellite is stored in order in five search engines, The current position is detected by data stored in a total of 20 search engines. The system 14 is, for example, a clock device, and displays the current position detected by the baseband processing unit 13. The power source 15 includes a small coin-type battery (for example, 2016 type) and a DC / DC converter, and supplies power to the RF unit 12, the baseband processing unit 13, and the system 14.

Many proposals have been made regarding position detection technology using GPS.
For example, in a proposed GPS navigation apparatus, ephemeris data is divided and collected in units of subframes and stored in a memory, thereby shortening the time required for data collection. Specifically, a subframe collection flag is provided, and this flag is set to 1 (valid) according to the collection of the subframe. Therefore, since it is determined by the flag whether or not the subframe has been collected once, it is not necessary to collect the subframe again, and the collection time can be shortened. (See Patent Document 1)
Further, in a proposed GPS receiver, a detection unit having a plurality of channels, a message collection unit that collects a navigation message transmitted from a satellite demodulated by the detection unit, a message analysis unit that analyzes the collected message, A positioning unit that calculates the position of the receiver from the propagation time and the position of the satellite, and a timing designating unit that designates a timing for scanning the navigation message for the message collection unit of each channel, and a navigation message in one or more channels When collecting messages, specify the message collection timing for other channels. Therefore, by quickly detecting a preamble pattern that is a bit pattern indicating the head of a navigation message transmitted from a GPS satellite, reducing the time to detect a preamble pattern in all channels, and quickly collecting navigation messages, Reduce positioning time. (See Patent Document 2)
In addition, in a proposed GPS receiver, GPS satellites can be captured in a plurality of channels, time information extracted from satellite data from the captured GPS satellites, and current time measured on the GPS receiver side Based on the time, the distance between the GPS satellite and the current position (the position of the GPS receiver) is measured. Further, the detailed orbit information (ephemeris) included in the satellite data is taken out, the satellite position is calculated, and the position of the GPS receiver is calculated in consideration of the measured distance. As a result, synchronization with the satellite data can be established at an early stage, and the time required to start positioning is shortened. (See Patent Document 3)
In a proposed position detection device, data from GPS satellites received by a GPS receiver has a hierarchical structure of mainframe, subframe, and word, and a parity bit for checking is incorporated in each word check. Therefore, the GPS receiver performs a parity bit for each word and outputs how many words are MG in the parity check in the received subframe. The reception determination unit determines whether data reception is possible based on the number of parity checks MG. When it is determined that data cannot be received, the control unit turns off continuous energization for data collection, turns on the switch for data collection again after a predetermined time, and energizes the main power supply. As a result, when continuous energization is performed in order to acquire satellite orbit information, it takes a long time to collect data if the reception environment is bad, thereby avoiding unnecessary power consumption. (See Patent Document 4)
JP-A-3-42793 Japanese Patent Laid-Open No. 11-304899 JP 2000-292521 A JP 2003-194910 A

In the conventional position detection using the GPS including the above-described Patent Documents 1 to 4, the first to fifth subframes are continuously acquired. Since the five subframes are 30 seconds, if the margins before and after are included, the time for continuous energization needs 40 seconds or more. However, in the case of the wristwatch position detection device of FIG. 7 using a coin-type battery or other portable position detection device, when a coin-type battery is used as a power source for supplying power to each part, 40 seconds. If the current is continuously applied, the discharge characteristics of the battery deteriorate, and the device itself may stop functioning due to a significant voltage drop of the battery.
The present invention is to solve such a conventional problem, and even when a coin-type battery or other small battery is used as a power source, a wasteful power consumption is avoided and a significant voltage drop of the battery is achieved. An object of the present invention is to make it possible to reliably receive a GPS signal from a satellite and detect the current position without causing a situation in which the function of the apparatus is stopped due to the occurrence of an error.

  In the operation mode in which power is supplied from a battery, the position detection device according to claim 1 includes m-th subframe data from the first to the m-th transmitted in time series from a satellite (in the embodiment, Is a receiving means for receiving a GPS signal carrying mainframe data with a period of 5 subframes (corresponding to 5 subframe data) and stopping reception in a non-operation mode in which power is not supplied from the battery (Embodiment) 1 and the operation control means for controlling the receiving means to switch from the non-operation mode to the operation mode and the control to switch from the operation mode to the non-operation mode (in the embodiment, Corresponding to the CPU 31 in FIG. 1) and m by the receiving means when the operation control means switches from the non-operation mode to the operation mode. Acquisition determination means for determining whether or not all of the subframe data has been acquired (corresponding to the CPU 31 in FIG. 1 in the embodiment), and acquisition determination that all of the m subframe data have not been acquired When determined by the means, the time for intermittent switching from the non-operation mode to the operation mode is calculated in accordance with the transmission of the subframe data that could not be acquired, and based on the calculated switching time for the operation control means When the acquisition determining unit determines that the calculation unit (in the embodiment, corresponding to the CPU 31 in FIG. 1) that instructs the control and all the m pieces of subframe data have been acquired, the acquired Position calculation means for calculating the current position based on the position information included in the m pieces of subframe data (in the embodiment, the CP of FIG. And corresponding) 31 has a structure equipped with.

  The position detection device according to claim 1, further comprising a plurality of storage means (in the embodiment, corresponding to n search engines 32 of FIG. 1), as described in claim 2, The subframe data of the satellites obtained in order from the GPS signals received by the receiving means are assigned to the respective memories allocated in correspondence with the identification information of the satellites (corresponding to the TLM data of FIG. 2 in the embodiment). Stored in each of the storage means, when m subframe data of the satellites corresponding to each of the predetermined number of storage means (corresponding to 3 or 4 in the embodiment) are stored. Alternatively, the current position may be calculated based on the position information included in the m subframe data.

  In the position detection device according to claim 1, as described in claim 3, before the operation control means is instructed to perform control based on the switching time from the calculation means, any k (1 ≦ k ≦ m) th The receiving means may be switched from the non-operation mode to the operation mode for one period (in the embodiment, corresponding to a period of 30 seconds) from the detection of the head synchronization signal of the subframe data. .

  In the position detection device according to claim 3, as described in claim 4, the acquisition determination unit is configured to perform a predetermined time (in the embodiment, after the reception unit is switched from the non-operation mode to the operation mode by the operation control unit. If the head synchronization signal of any subframe data cannot be detected even after elapse of at least the time corresponding to 6 seconds of subframe data), the receiving means is changed from the operation mode to the non-operation mode for the operation control means. You may make it the structure which instruct | indicates to switch.

According to a fifth aspect of the present invention, in the operation mode in which power is supplied from the battery, the first to mth subframe data (in the embodiment) transmitted from the satellite in time series. Is a receiving means for receiving a GPS signal carrying mainframe data with a period of 5 subframes (corresponding to 5 subframe data) and stopping reception in a non-operation mode in which power is not supplied from the battery (Embodiment) 1 corresponds to the RF unit 2 in FIG. 1) and performs control for switching from the non-operation mode to the operation mode and control for switching from the operation mode to the non-operation mode. Step B for determining whether or not all m subframe data have been acquired by the receiving means when switched to the mode. When it is determined in step B that all of the m subframe data cannot be acquired, the time for intermittently switching from the non-operation mode to the operation mode in accordance with the transmission of the subframe data that could not be acquired. When step B determines that all of the m pieces of subframe data have been acquired, and step C that calculates and instructs control based on the calculated switching time to step A, the acquisition is performed. Step D for calculating the current position based on the position information included in the m pieces of subframe data is executed.
Step A to step D correspond to the processing of the CPU 31 in FIG. 1 in the embodiment.

  In the position detection method according to claim 5, as described in claim 6, in step D, the subframe data of the satellites acquired in order from the GPS signals received by the receiving means are stored in a plurality of storage means (embodiments). Is stored in one storage means allocated corresponding to the identification information of the satellite in the search engine 32 in FIG. 1), and a predetermined number (3 in the embodiment). (Corresponding to 4) storage means, when the m subframe data of the satellite corresponding to each of the storage means is stored, the position information included in the m subframe data stored in each storage means The current position may be calculated based on the current position.

  In the position detection method according to claim 5, as described in claim 7, before step A is instructed to perform control based on the switching time from step C, an arbitrary k (1 ≦ k ≦ m) th sub The receiving unit may be switched from the non-operation mode to the operation mode for a period of one cycle (in the embodiment, corresponding to a period of 30 seconds) from the detection of the leading synchronization signal of the frame data.

  In the position detection method according to claim 7, as described in claim 8, the step B includes a predetermined time (in the embodiment, at least 1 after the receiving unit is switched from the non-operation mode to the operation mode by the step A). If the synchronization signal at the head of any subframe data cannot be detected even after elapse of 6 seconds of subframe data), the receiving means is switched from the operation mode to the non-operation mode for step A. You may comprise so that it may instruct | indicate to switch.

  According to the present invention, even when a coin-type battery or other small battery is used as a power source, useless power consumption is avoided, and a significant voltage drop of the battery occurs, causing the device to stop functioning. Without incurring an error, the GPS signal from the satellite can be reliably received and the current position can be detected.

  Hereinafter, embodiments of a position detection device and a position detection method according to the present invention will be described in detail with reference to FIGS. 1 to 6. The following embodiment is an example for realizing the present invention, and the present invention is not limited to the following embodiment. That is, it goes without saying that the present invention can be variously modified by those skilled in the art as long as the technical scope of the present invention belongs.

FIG. 1 is a block diagram showing a configuration of a position detection device in each embodiment of the present invention. As shown in FIG. 1, the antenna 1, the RF unit 2, the baseband processing unit 3, the system 4, and the power source 5 are configured.
The antenna 1 receives radio waves from the satellite and inputs them to the RF unit 2. The RF unit 2 extracts and demodulates only the GPS signal from the input radio wave, amplifies it to a required level, converts it from an analog signal to a digital baseband signal, and inputs it to the baseband processing unit 3 . The baseband processing unit 3 includes a CPU 31, n search engines 32, a synchronization detection unit 33, an RF control unit 34, a RAM 35, and the like. The synchronization detection unit 33 detects a preamble that is an 8-bit synchronization signal at the head of each subframe, and inputs the start timing of the subframe to the CPU 31. In response to a GPS signal acquisition instruction from the system 4, the CPU 31 switches the RF unit 2 from the non-operation mode to the operation mode by the RF control unit 34, and n searches based on the preamble from the synchronization detection unit 33. -Start the engine 32. Each search engine takes one subframe and stores the satellite identified by the data and the number of subframes in an internal memory (not shown). The CPU 31 stores the number of satellites and subframes stored in each of the n search engines 32 in the RAM 35 for management. That is, it is managed whether or not all of the first to fifth subframes transmitted from a predetermined number (for example, four) of satellites have been received. The RF control unit 34 controls the RF unit 2 in an operation mode or a non-operation mode according to a command from the CPU 31. In the operation mode, the clock of the RF unit 2 is enabled to enable the signal processing of the RF unit 2 described above. On the other hand, in the non-operation mode, the clock of the RF unit 2 is enabled and the signal processing of the RF unit 2 is stopped. Note that the RF control unit 34 is not necessarily configured by such a dedicated hardware system 4. A configuration in which the RF unit 2 is controlled to an operation mode or a non-operation mode by a control signal from the CPU 31 may be used. The system 4 is a clock device, for example, and displays the current time and the current position detected by the baseband processing unit 3. The power supply 5 includes a small coin-type battery (for example, 2016 type) and a DC / DC converter, and supplies power to the RF unit 2, the baseband processing unit 3, and the system 4. However, in the non-operation mode, the RF unit 2 does not consume power because the signal processing is stopped.

  FIG. 2 is a diagram illustrating a frame configuration in the GPS signal. FIG. 2A shows a main frame transmitted every 30 seconds from 32 satellites. Each main frame is composed of five subframes of subframes 1 to 5. Subframe 1 to subframe 3 are composed of unique data (referred to as “ephemeris”) in each satellite, and subframe 4 and subframe 5 are common to 32 satellites that transmit GPS signals in synchronization. It consists of data (referred to as “almanac”). When all the data of these five subframes are acquired, position information corresponding to the satellite is obtained. In order to detect the current position of this device, it is necessary to acquire position information corresponding to each of the four (at least three) satellites, so a total of 20 subframes are acquired. However, in the present invention, as will be described later, five consecutive subframes transmitted simultaneously from each satellite are divided and acquired.

  FIG. 2B shows each 300-bit subframe having a time length of 6 seconds. Usually, at the beginning of each subframe, there is 30-bit TLM (Telemetry) data, followed by 30-bit HOW (Handover Word) data, followed by a 240-bit clock and each satellite. State data (subframe 1), ephemeris data such as detailed orbit information unique to each satellite (subframes 2 and 3), almanac data such as rough orbit information common to 32 satellites and ionosphere correction information ( There are subframes 4, 5). Although not shown in the figure, the first 8 bits (10001011) of the TLM are a preamble pattern, and constitute a synchronization signal indicating the start of a subframe.

  In this way, the GPS signals from 32 satellites have the transmission timing of each subframe synchronized, and if the TLM of any subframe of any satellite is obtained, the satellite of that subframe is identified, It is possible to recognize the number of the subframe among the five subframes. Further, it is possible to predict the transmission timing of any other subframe based on the acquired TLM data of the subframe. The present invention detects the current position by utilizing such a characteristic configuration of the subframe.

3 to 5 are flowcharts showing the position detection method of the embodiment executed by the CPU 31.
In FIG. 3, after a predetermined initialization process (step S1), the CPU 31 determines whether or not there is a GPS signal acquisition instruction from the system 4 (step S2). The RF controller 34 is instructed to turn on (step S3), and a period in which five subframes transmitted in time series can be received, that is, a period of about 30 seconds in which one main frame can be received. 2 is switched from the non-operation mode to the operation mode.

  After switching the RF unit 2 to the operation mode, the CPU 31 determines whether or not synchronization establishment is detected by the synchronization detection unit 33, that is, whether or not an 8-bit preamble at the head of each subframe is detected. (Step S4) If the establishment of synchronization is not detected, it is determined whether or not a predetermined time has elapsed from the ON instruction of the RF unit 2 (Step S5). When the predetermined time has elapsed, the process proceeds to Step S2. Whether or not there is a GPS signal acquisition instruction from the system 4 is determined. If a predetermined time has not elapsed, it is determined whether or not synchronization establishment is detected in step S4. Since the preamble at the head of each subframe is transmitted from each satellite in a cycle of 6 seconds, this predetermined time is set to a time of 6 seconds of at least one subframe data.

  When the CPU 31 detects establishment of synchronization in step S4, the CPU 31 stores the synchronization detection timing in the RAM 35 (step S6), starts data acquisition from the search engine unit 32 (step S7), and acquires frame data. (Step S8), the subframe number and the subframe data are stored in the RAM 35 (Step S9), and it is determined whether or not 30 seconds, which is the period of the main frame, has elapsed since the synchronization detection (Step S10). If the second has not elapsed, the processing from step S8 to step S10 is repeated.

  When 30 seconds have elapsed from the establishment of synchronization, the CPU 31 extracts the subframe numbers stored in the RAM 35 in the flowchart of FIG. 4 (step S11), and determines whether or not all five subframe numbers are available. (Step S12), if all of them are available, the stored frame data is sent to the system 4 (step S13), and the RF unit 2 is turned off with respect to the RF control unit 34. (Step S14), the process proceeds to step S2 in FIG. 3, and it is determined whether or not there is a GPS signal acquisition instruction from the system 4. This state is a case where five subframe data can be acquired at a time because the reception environment is good.

  On the other hand, if all the five subframe numbers are not complete, the CPU 31 instructs the RF control unit 34 to turn off the RF unit 2 (step S15), and the missing subframe number. Is extracted (step S16), and based on the synchronization detection timing stored in the RAM 35, the next timing time at which the missing subframe data can be acquired is calculated (step S17), and the calculated timing time has elapsed. (Step S18), and when the timing time has elapsed, the RF control unit 34 is instructed to turn on the RF unit 2 (step S19). When there are a plurality of missing subframes and they are not continuous, the calculation time for switching from the non-operation mode to the operation mode is a plurality of intermittent calculation times as in the example of FIG. become.

  Thereafter, in the flowchart of FIG. 5, the CPU 31 acquires the subframe data received from the RF unit 2 (step S20), and instructs the RF control unit 34 to turn off the RF unit 2 (step S20). S21), the subframe number and subframe data are added and stored in the RAM 35 (step S22), and it is determined whether or not the data acquisition has been completed for all the calculation times (step S23). If the data acquisition for all the calculation times has not been completed, the CPU 31 proceeds to step S18 in FIG. 4 and repeats the processing up to step S23 in FIG. 5 to acquire the data for all the calculation times. When the process is completed, the process proceeds to step S2 in FIG. 3 to determine whether or not there is a GPS signal acquisition instruction from the system 4.

  FIG. 6 is a diagram illustrating an example of switching timing between the operation mode and the non-operation mode for the RF unit 2. In the example of FIG. 6A, as a result of detecting the subframe data by turning on the RF unit 2 for 30 seconds from the timing when the synchronization establishment of the first subframe is detected, the second and fourth subframe data are detected. This is a case where the subframe could not be acquired. Therefore, the next timing time when the missing second and fourth subframe data can be acquired is calculated, and the RF unit 2 is turned on. In this case, the number of times of switching from the non-operation mode to the operation mode is two. In the example of FIG. 6B, as a result of detecting the subframe data by turning on the RF unit 2 for 30 seconds from the timing when the synchronization establishment of the fourth subframe is detected, the first and second subframes are detected. This is a case where the subframe could not be acquired. Therefore, the next timing time at which the missing first and second subframe data can be acquired is calculated, and the RF unit 2 is turned on. In this case, the number of times of switching from the non-operation mode to the operation mode is one.

As described above, according to this embodiment, in the operation mode in which power is supplied from the battery, the RF unit 2 transmits the m sub-numbers from the first to the m-th transmitted in time series from the satellite. A GPS signal carrying main frame data with a period of frame data as one cycle is received, and reception is stopped in a non-operation mode in which power is not supplied from the battery.
The CPU 31 controls the RF unit 2 to switch from the non-operation mode to the operation mode and control from the operation mode to the non-operation mode by the RF control unit 34, and when switching from the non-operation mode to the operation mode, the RF 31 The unit 2 determines whether or not all of the five subframe data have been acquired. When it is determined that not all of the five subframe data have been acquired, A time for intermittent switching from the non-operation mode to the operation mode is calculated in accordance with transmission, and the RF unit 2 is switched from the non-operation mode to the operation mode based on the calculated switching time, and five subframes When it is determined that all of the data has been acquired, the position information included in the acquired five subframe data The basis for calculating the current position.
Therefore, even when a coin-type battery or other small battery is used as a power source, wasteful power consumption is avoided, and a situation in which a significant voltage drop of the battery occurs and the device stops functioning is not caused. The GPS signal from the satellite can be reliably received and the current position can be detected.

In the above-described embodiment, the search engine 32 is further provided, and the CPU 31 uses the satellite identification information of the satellite subframe data obtained sequentially from the GPS signals received by the RF unit 2. Each search engine assigned corresponding to the data of a certain TLM is stored, and three or four search engines store five subframe data of three or four satellites. The current position is calculated based on position information included in the five subframe data stored in the engine.
Therefore, for example, even when arbitrary subframe data is sequentially acquired from 20 subframe data including 5 subframe data in 4 satellites, the on-time of the RF unit 2 is minimized. Even if a coin-type battery or other small battery is used as a power source, it avoids unnecessary power consumption, without causing a situation where a significant voltage drop of the battery occurs and the device stops functioning, The GPS signal from the satellite can be reliably received and the current position can be detected.

In the above embodiment, when the subframe data is first acquired, the CPU 31 detects the preamble that is the leading synchronization signal of any k (1 ≦ k ≦ 5) th subframe data, and from that time For 30 seconds for one cycle, the RF unit 2 is switched from the non-operation mode to the operation mode, and an attempt is made to acquire five subframe data. If there is subframe data that could not be acquired, the RF unit 2 is intermittently switched to the operation mode in accordance with the transmission of the subframe data in the next one cycle.
Therefore, when the reception environment is good and 5 subframe data can be acquired at the same time in the first cycle, intermittent operation mode switching is not necessary, and wasteful power consumption can be avoided.

In the above embodiment, when acquiring subframe data for the first time, the CPU 31 switches the RF2 from the non-operation mode to the operation mode, and then the preamble of the head of any subframe data even after a predetermined time has elapsed. Is not detected, the RF unit 2 is switched from the operation mode to the non-operation mode.
Therefore, wasteful power consumption can be avoided when the reception environment is bad.

The block diagram which shows the structure of the position detection apparatus in embodiment of this invention. The figure which shows the frame structure in a GPS signal. The flowchart of CPU which shows the position detection method in embodiment. The flowchart of CPU following FIG. 5 is a flowchart of the CPU following FIG. The figure which shows the example of the switching timing of the operation mode with respect to RF part, and a non-operation mode. The block diagram which shows the structure of the position detection apparatus in a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Antenna 2 RF part 3 Baseband part 4 System 31 CPU
32 Search Engine 33 Synchronization Detection Unit 34 RF Control Unit 35 RAM

Claims (8)

In an operation mode in which power is supplied from a battery, a GPS signal carrying mainframe data having a period of m subframe data from the first to mth transmitted in time series from a satellite as one cycle Receiving means for receiving and stopping reception in a non-operation mode in which power is not supplied from the battery;
Operation control means for performing control for switching from the non-operation mode to the operation mode and control for switching from the operation mode to the non-operation mode for the reception means;
An acquisition determination unit that determines whether or not all m subframe data have been acquired by the reception unit when the operation control unit is switched from the non-operation mode to the operation mode;
When it is determined by the acquisition determining unit that all of the m subframe data cannot be acquired, the time for intermittently switching from the non-operation mode to the operation mode in accordance with the transmission of the subframe data that could not be acquired. Calculating means for instructing the operation control means to perform control based on the calculated switching time;
When the acquisition determining unit determines that all m pieces of subframe data have been acquired, the current position is calculated based on the position information included in the acquired m pieces of subframe data. Position calculating means;
A position detection device comprising:   A plurality of storage means, wherein the position calculating means assigns the subframe data of the satellites obtained in order from the GPS signals received by the receiving means to each storage means assigned in correspondence with the identification information of the satellites; Based on the position information included in the m subframe data stored in each storage means when storing the m subframe data of the satellite corresponding to each of the predetermined number of storage means. The position detection apparatus according to claim 1, wherein the current position is calculated.   The operation control means is one cycle from when the head synchronization signal of any k (1 ≦ k ≦ m) -th subframe data is detected before the operation means is instructed to control based on the switching time. 2. The position detecting device according to claim 1, wherein the receiving unit is switched from a non-operation mode to an operation mode for a period.   The acquisition determining means, when the receiving means is switched from the non-operation mode to the operation mode by the operation control means, when the synchronization signal at the head of any subframe data cannot be detected even after a predetermined time has passed, 4. The position detecting device according to claim 3, wherein the position detecting device instructs the operation control unit to switch the receiving unit from an operation mode to a non-operation mode. In an operation mode in which power is supplied from a battery, a GPS signal carrying mainframe data having a period of m subframe data from the first to mth transmitted in time series from a satellite as one cycle Step A for performing a control to switch from the non-operation mode to the operation mode and a control to switch from the operation mode to the non-operation mode for the receiving means that receives and stops receiving in the non-operation mode in which power is not supplied from the battery;
Step B for determining whether or not all m subframe data have been acquired by the receiving means when the non-operation mode is switched to the operation mode by Step A;
When it is determined in step B that all of the m subframe data cannot be acquired, the time for intermittently switching from the non-operation mode to the operation mode in accordance with the transmission of the subframe data that could not be acquired. Calculating and instructing step A to perform control based on the calculated switching time;
a step of calculating a current position based on position information included in the acquired m subframe data when it is determined in step B that all of the m subframe data have been acquired; D,
Position detection method to execute.   In the step D, the subframe data of the satellite acquired in order from the GPS signal received by the receiving means is stored in one storage means assigned in correspondence with the identification information of the satellite in the plurality of storage means. Based on the position information included in the m subframe data stored in each storage means when storing the m subframe data of the satellite corresponding to each of the predetermined number of storage means. The position detection method according to claim 5, wherein the current position is calculated.   The step A is a period of one cycle from when the head synchronization signal of any k (1 ≦ k ≦ m) subframe data is detected before the control based on the switching time is instructed from the step C. 6. The position detection method according to claim 5, wherein the receiving means is switched from a non-operation mode to an operation mode.   In the step B, when the reception means is switched from the non-operation mode to the operation mode in the step A, if the synchronization signal at the head of any subframe data cannot be detected even after a predetermined time has elapsed, the step A The position detection method according to claim 7, wherein the receiving unit is instructed to switch from the operation mode to the non-operation mode.

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