JP2007271536A - Timepiece and time correction method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce electric power consumed by internal time correction using GPS signals and highly accurately perform internal time correction. <P>SOLUTION: A timepiece includes a reception part 22 for receiving one item of navigation data from items of navigation data of GPS signals received from a plurality of GPS satellites; a time measuring part 17 for measuring current time and storing it as internal time data; a GPS satellite determination means for determining a plurality of GPS satellites from which navigation data can be received; an elevation angle computation means for computing angles of elevation of the determined plurality of GPS satellites; a GPS satellite selection means for selecting a GPS satellite having a high angle of elevation among the plurality of GPS satellites from which navigation data can be received; an acquisition means for receiving navigation data from the GPS satellite selected by the reception part 22 and acquiring GPS time data included in navigation data; and a CPU 11 as an internal time correction means for correcting internal time data on the basis of the acquired GPS time data. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a timepiece device and a time correction method.

  Conventionally, there has been a GPS receiver that receives a GPS signal from a GPS (Global Positioning System) satellite and measures its own position. A GPS signal transmitted from a GPS satellite includes a C / A code (Coarse / Acquisition code). The C / A code includes navigation data (navigation message) indicating the orbit of the GPS satellite.

  The C / A code is a code in which different values are assigned to 28 GPS satellites. Therefore, the GPS receiver can select the GPS satellite and receive the GPS signal by collating the C / A code of the GPS satellite to be received with the C / A code in the GPS signals received simultaneously. Further, the GPS receiver includes a time measuring unit that measures the current time and outputs the current time data (hereinafter referred to as internal time data).

  The GPS receiver selects three or four GPS satellites from receivable GPS satellites, and measures the position of the own aircraft based on the navigation data of the GPS signals received from the selected GPS satellites and the internal time data To do.

  In addition, the navigation data includes accurate time information of an atomic clock mounted on the transmission source GPS satellite.

A technique for correcting the internal time of the GPS receiver using time information included in the navigation data is considered. For example, a configuration in which signals (GPS signals) transmitted from a plurality of positioning satellites (GPS satellites) are received, the position of the reception point is measured, and internal time data is corrected using time information in the GPS signals (For example, refer to Patent Document 1).
JP-A-9-178870

  However, in the conventional configuration, when the internal time data is corrected, it is necessary to drive at least three reception channels at the same time in order to receive GPS signals from at least three GPS satellites. For this reason, the power consumption of the GPS receiver is large.

  Further, when the internal time data is corrected, there is a request for receiving the GPS signal time information without being affected by the troposphere and noise from the GPS satellite and correcting the internal time data with high accuracy.

  An object of the present invention is to reduce power consumption in internal time correction using GPS signals and to perform internal time correction with high accuracy. More specifically, GPS time data is received from one GPS satellite having a high elevation angle that is not easily affected by the troposphere and noise, and the internal time is corrected.

In order to solve the above problems, the timepiece device of the present invention includes:
Receiving means (for example, receiving unit 22 in FIG. 1; step S2 in FIG. 8; steps S17 and S19 in FIG. 9) for receiving one navigation data among navigation data of GPS signals transmitted from a plurality of GPS satellites;
Clocking means (for example, the clocking unit 17 in FIG. 1) for clocking the current time and holding it as internal time data;
GPS satellite determining means (for example, CPU 11 in FIG. 1; step S12 in FIG. 9) for determining a plurality of GPS satellites capable of receiving the navigation data;
An elevation angle calculating means (for example, CPU 11 in FIG. 1; step S13 in FIG. 9) for calculating the elevation angles of a plurality of GPS satellites determined by the GPS satellite determining means;
Based on the elevation angle calculated by the elevation angle calculation means, GPS satellite selection means (for example, the CPU 11 in FIG. 1; FIG. 1) selects one of the plurality of GPS satellites capable of receiving navigation data and having a high elevation angle. 8 step S1; FIG. 9 step S15);
Acquisition means (for example, CPU 11 in FIG. 1; step S3 in FIG. 8) that causes the reception means to receive navigation data from the GPS satellite selected by the GPS satellite selection means and acquires GPS time data included in the navigation data. Step S19) of FIG.
Internal time correction means (for example, CPU 11 in FIG. 1; steps S4 and S5 in FIG. 8; steps S20 and S21 in FIG. 9) for correcting the internal time data based on the GPS time data acquired by the acquisition means;
It is characterized by providing.

The invention according to claim 2 is the timepiece device according to claim 1,
It further comprises storage means (for example, storage unit 15 in FIG. 1) for storing orbit information of GPS satellites and position data of its own device,
The GPS satellite determining means selects a plurality of GPS satellites capable of receiving the navigation data based on orbit information stored in the storage means, position data of the device itself, and internal time data held in the time measuring means. Decide
The elevation angle calculating means calculates elevation angles of the determined plurality of GPS satellites based on the orbit information, the position data of the device itself, and the internal time data.

The invention according to claim 3 is the timepiece device according to claim 1 or 2,
The internal time correction means calculates correction data based on the GPS time data acquired by the acquisition means, the distance between the GPS satellite and the device received by the reception means, the internal processing time, and the leap second. The internal time data is corrected by the correction data.

The time correction method of the invention described in claim 4 is:
A GPS satellite determining step (for example, step S12 in FIG. 9) for determining a plurality of GPS satellites capable of receiving GPS signal navigation data;
An elevation angle calculation step (for example, step S13 in FIG. 9) for calculating the elevation angles of a plurality of GPS satellites determined by the GPS satellite determination step;
A selection step (for example, step S1 in FIG. 8; FIG. 9) of selecting any one of the plurality of GPS satellites capable of receiving navigation data based on the elevation angle calculated in the elevation angle calculation step. Step S15),
Of the navigation data transmitted from a plurality of GPS satellites, receiving one navigation data corresponding to the GPS satellite selected by the selection step, and acquiring GPS time data included in the navigation data (for example, Step S3 in FIG. 8; Step S19 in FIG.
Based on the GPS time data acquired by the acquisition process, an internal time correction process (for example, steps S4 and S5 in FIG. 8; steps S20 and S21 in FIG. 9) for correcting the internal time data held in the time measuring means; ,
It is characterized by including.

The invention according to claim 5 is the time correction method according to claim 4,
In the GPS satellite determination step, a plurality of GPS satellites capable of receiving the navigation data are determined based on the orbit information of the GPS satellites stored in the storage means, the position data of the own device, and the internal time data,
In the elevation angle calculating step, the elevation angles of the determined plurality of GPS satellites are calculated based on orbit information stored in the storage means, the position data of the own device, and the internal time data. It is characterized by.

The invention according to claim 6 is the time correction method according to claim 4 or 5,
In the internal time correction step, correction data is calculated based on the GPS time data acquired in the acquisition step, the distance between the GPS satellite and the device received in the acquisition step, the internal processing time, and the leap second. The internal time data is corrected by the correction data.

  According to the first and fourth aspects of the invention, since one GPS satellite is selected and GPS time data is received and acquired, the power consumption in the internal time adjustment using the GPS signal can be reduced, and the elevation angle can be reduced. GPS time data is received and acquired by selecting one high GPS satellite, so the internal time correction is performed with high accuracy using GPS time data from a GPS satellite with a high elevation angle that is not easily affected by the troposphere and noise. be able to.

  According to the second and fifth aspects of the present invention, the elevation angle can be calculated by using the orbit information of the GPS satellite, the own device position data, and the internal time data.

  According to the third and sixth aspects of the present invention, the correction data is calculated based on the GPS time data, the received GPS satellite and the distance of the device itself, the internal processing time, and the leap second. The internal time can be corrected with higher accuracy.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings. The present invention is not limited to the illustrated example.

  First, the apparatus configuration of the present embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 shows a configuration of a timepiece device 100 according to the present embodiment. FIG. 2A shows the storage configuration of the ROM 16. FIG. 2B shows a storage configuration of the storage unit 15. FIG. 2C shows the storage configuration of the RAM 13.

  As shown in FIG. 1, the timepiece device 100 according to the present embodiment includes a main body 10 and a receiving unit 20. The main unit 10 includes a CPU (Central Processing Unit) 11, an operation unit 12, a RAM (Random Access Memory) 13, a display unit 14, a storage unit 15, a ROM (Read Only Memory) 16, and a clock. And a portion 17.

  The CPU 11 develops a program designated from the system program and various application programs stored in the ROM 16 in the RAM 13 and executes various processes in cooperation with the program expanded in the RAM 13.

  The CPU 11 selects one GPS satellite with a high elevation angle in cooperation with a first time correction program described later, acquires HOW data as GPS time data of the GPS signal of the selected GPS satellite, and corrects the correction data. And the internal time data of the time measuring unit 17 is corrected based on the correction data.

  The operation unit 12 includes various keys for causing the timepiece device 100 to execute various functions. When these keys are operated and input, operation signals corresponding to these keys are output to the CPU 11.

  The RAM 13 is a volatile memory that stores various types of information, and has a work area for developing various programs and data.

  As shown in FIG. 2C, the RAM 13 includes data areas 131 to 135 and a program area 136 as storage areas. In a first time correction process to be described later, each of the satellite numbers (satellite numbers ID-m,..., ID-p: all satellite numbers ID-1 to ID-n described later) is stored in the data area 131. 1) is stored. The data area 132 stores the elevation angle (elevation angles θ1 to θq, where q is the number of visible satellites) of each GPS satellite of the satellite number of the visible satellite. The data area 133 stores one satellite number (ID-r: one of satellite numbers ID-m,..., ID-p) of the selected visible satellite. The data area 134 stores the distance between the receiving GPS satellite and the device itself. The data area 135 stores correction data for correcting the internal time data. In the program area 136, the first time correction program is expanded.

  The display unit 14 includes a small LCD (Liquid Crystal Display), an ELD (ElectroLuminescent Display), and the like, and displays various information based on display information input from the CPU 11. For example, the display unit 14 digitally displays the internal time data measured by the clock unit 17 as the current time.

  The storage unit 15 includes a flash memory, an EEPROM (Electrically Erasable Programmable ROM), and the like, and stores information in a readable / writable manner.

  As shown in FIG. 2B, the storage unit 15 includes data areas 151 to 155 as storage areas. The data area 151 stores satellite numbers for identifying all GPS satellites (satellite numbers ID-1 to ID-n, where n is the number of all satellites). The data area 152 stores almanac data as trajectory information described later. The data area 153 stores its own device position data. The data area 154 stores an internal processing time. The data area 155 stores leap second data described later.

  The own device position data is the position data of the timepiece device 100, and is input by the user via the operation unit 12 and stored in the storage unit 15, for example. The own device position data may include information on the height of the timepiece device 100. The internal processing time is information indicating the preset internal processing time of the clock device 100, and is time information indicating the processing time of the CPU 11 and the like from when the GPS signal is obtained until the internal time data is corrected.

  The ROM 16 is a memory that stores information in a readable manner. As shown in FIG. 2A, the ROM 16 includes a program area 161 and a data area 162. The program area 161 stores a first time correction program. In the data area 162, C / A codes of all GPS satellites are stored.

  The timer unit 17 counts a signal input from an oscillation circuit unit (not shown), holds it as internal time data that changes with time, and outputs the internal time data to the CPU 11. Here, the internal time data refers to the current time data measured by the timer unit 17. Further, the timer unit 17 corrects the internal correction data based on the correction instruction information input from the CPU 11.

  The receiving unit 20 includes a signal processing CPU 21, a receiving unit 22, a RAM 23, and a ROM 24.

  The signal processing CPU 21 is configured by a DSP (Digital Signal Processor) or the like and performs reception processing. Here, the reception process is a process of demodulating the navigation data from the GPS signal received by the receiving unit 22 and transferring the navigation data to the CPU 11.

  The receiving unit 22 includes an antenna, an amplifier, a mixer, etc. (not shown). The receiving unit 22 receives a GPS signal with an antenna (not shown), amplifies the received GPS signal, and performs frequency conversion to a signal in an intermediate frequency band sufficiently lower than the carrier wave for tuning. The receiving unit 22 is configured to have one channel and can receive GPS signals from one GPS satellite at the same time.

  The signal processing CPU 21 develops a program designated from the system program and various application programs stored in the ROM 24 in the RAM 23 and executes various processes in cooperation with the program expanded in the RAM 23. For example, the ROM 24 stores a program for demodulating navigation data.

  For example, with the GPS signal transmitted from the receiving unit 22 as a trigger, the navigation data is demodulated in cooperation with the signal processing CPU 21 and the program for demodulating the navigation data read from the ROM 24 and developed in the RAM 23. The program is executed.

  Here, processing for demodulating the navigation data will be described. The signal processing CPU 21 performs phase synchronization between an arbitrary C / A code in the ROM 16 input from the CPU 11 and the C / A code of the GPS signal received from the GPS satellite by the receiving unit 22. Then, after phase synchronization is achieved, the navigation data can be demodulated by performing despreading.

  Next, an overview of GPS will be described with reference to FIGS. 3 and 4.

  A part in the outer space of the entire GPS system is called a space segment, a ground part is called a control segment, and a user receiver is called a user segment. GPS satellites belong to the space segment. The GPS satellite is not a geostationary satellite, but orbits the altitude of 20,000 km and changes its position with respect to the earth. The space and control segments are developed and operated by the US military, but the user segment must be designed and manufactured by the user. Therefore, the specification of the signal transmitted from the GPS satellite is defined in detail, and the document is made public. This document is named an Interface Control Document (abbreviated as ICD). The version of this ICD has been updated, for example, GPS-ICD-200.

  Currently, radio signals (GPS signals) are transmitted from 28 GPS satellites. The frequency of a radio signal transmitted by a GPS satellite is basically 1575.42 MHz (name: L1 wave), and a signal called a C / A code for civil use is placed on this frequency.

  FIG. 3 shows the format of the navigation data. FIG. 3A shows the frame structure of the navigation data. FIG. 3B shows a subframe configuration of navigation data. The navigation data in the format shown in FIG. 2 is described by the C / A code and transmitted from the GPS satellite. The navigation data includes trajectory information, time information, and the like. The data rate of the navigation data is 50 bps.

  One cycle of the navigation data is called in units of frames and has the structure shown in FIG. One frame is 1500 bits. In a GPS satellite, it takes 30 seconds to transmit one frame. The frame is composed of five subframes (300 bits each), and transmission is started in order from subframe 1. When transmission of subframe 5 is completed, transmission returns to transmission of subframe 1 again.

  FIG. 4 shows a schematic configuration of the subframe. As shown in FIG. 4, among the five subframes constituting the frame, subframes 1 to 3 include clock correction information and orbit information (ephemeris) of the transmitting GPS satellite itself. For subframes 4 and 5, all satellites transmit the same contents, and the contents are rough orbit information (almanac) and ionosphere correction information of all GPS satellites (up to 32 satellites) in orbit. However, since these have a large amount of data, they are further divided into pages and accommodated in subframes.

  That is, as shown in FIG. 3A, the data transmitted in the subframes 4 and 5 are divided into pages 1 to 25, and the contents of different pages are sequentially transmitted for each frame. It takes 25 frames to transmit all page contents, and it takes 12 minutes and 30 seconds to get all the navigation data information.

  The inside of the subframe is divided into units called words as shown in FIGS. One word is 30 bits, and one subframe corresponds to 10 words. Each word is composed of a 24-bit data portion and 6 bits for parity check. At the beginning of each subframe, a TLM (TeLeMetry) word and then a HOW (HandOver Word) are described. The TLM word includes a synchronization pattern, and the HOW includes GPS signal time information.

  The time in the GPS signal is managed in units of one week. The beginning of the week is 0:00 on every Sunday (24:00 on Saturday), and the time is expressed by the elapsed time (TOW (Time Of Week)). The HOW includes a number representing this elapsed time in 1.5 second units, and gives a clue that the receiver knows the current time. Each week is assigned a number (week number: WN (Week Number)), and the week starting at 00:00:00 on January 6, 1980 is set to week number 0. From this point, the week number is incremented by 1 every week. For example, the week number of the week starting on October 10, 2004 is 1292.

  The navigation data is divided and accommodated in the five subframes. Hereinafter, some items will be described, but the details can be understood by referring to GPS-ICD-200 or the like.

  FIG. 5 shows the contents of subframe 1. The subframe 1 of the navigation data contains a numerical value representing the state of the GPS satellite itself that is transmitting the navigation data and a clock correction coefficient. As shown in FIG. 5, following the first TLM word and HOW, the above-described words of the week number WN, ranging accuracy URA, and satellite health state SVhealth are described.

  Ranging accuracy URA is a rough standard of ranging accuracy when a pseudo-range (a distance between a GPS satellite and a receiver measured by adding an error due to advance of a receiver clock) is measured by the satellite. In the case of, it means that something is wrong. The satellite health state SVhealth is a code indicating the state of the satellite, and when it is not 0, it indicates that there is some abnormality.

  The subframes 2 and 3 store the orbit information of each satellite (refer to GPS-ICD-200 for details). Such orbit information is called ephemeris, and the position of the GPS satellite at an arbitrary time can be calculated.

  The rough orbit information for all GPS satellites is called almanac (almanac data), and is stored in pages 2 to 5 and 7 to 10 of subframe 4 and pages 1 to 24 of subframe 5, for a total of 32 pages. Corresponds to the GPS satellite of the aircraft. The almanac data is included in the subframe of the GPS signal and is also stored in the storage unit 15 in the timepiece device 100 as a receiver. The almanac data stored in the storage unit 15 is updated with the received almanac data once every several months.

  FIG. 6 shows the contents of a subframe including almanac data. As shown in FIG. 5, TLM word and HOW are described at the head of the subframe.

The ionosphere distributed at an altitude of 100 km or more has a function of delaying radio waves, and information for correcting the delay amount is contained in page 18 of subframe 4. FIG. 7 shows the contents of page 18 of subframe 4. Again, the TLM word and HOW are described at the head of the subframe. The page 18 of the subframe 4 includes the current leap second Δt _LS . This leap second Δt _LS is stored as leap second data in the storage unit 15 of the timepiece device 100 so that the timepiece device 100 can be updated with the received leap second.

  Next, the operation of the timepiece device 100 according to the present embodiment will be described with reference to FIGS. FIG. 8 shows a flow of time correction processing (outline). First, an outline of time correction processing in the timepiece device 100 will be described with reference to FIG.

  The time correction process in FIG. 8 is executed by the cooperation of the CPU 11 and the time correction program in the timepiece device 100. In the timepiece device 100, first, one GPS satellite capable of receiving a GPS signal is selected (step S1). Then, the navigation data of the GPS signal is started to be received from the GPS satellite selected in step S1 via the receiving unit 20 (step S2).

  Then, HOW (hereinafter referred to as HOW data) is extracted from the navigation data received in step S2 (step S3). Then, correction data for the internal time data is calculated based on the HOW data extracted in step S3 (step S4). Then, based on the correction data calculated in step S4, the internal time data of the time measuring unit 17 is corrected (step S5), and the time correction process is ended.

  Next, the first time adjustment process as one form of the time adjustment process of FIG. 8 will be described. FIG. 9 shows the flow of the first time correction process.

  For example, in the timepiece device 100, the first time adjustment processing program read from the ROM 16 and expanded in the RAM 13 triggered by the input of the execution instruction of the first time adjustment processing via the operation unit 12 or the like. The first time adjustment process is executed in cooperation with the CPU 11.

  As shown in FIG. 9, first, the almanac data and the own device position data are read from the storage unit 15, and the internal time data is acquired from the time measuring unit 17 (step S11). The own apparatus position data may be acquired by an input from the user via the operation unit 12.

  Then, the current position data of all GPS satellites is calculated from the almanac data and the internal time data acquired in step S1, and the current GPS signal is calculated based on the current position data of all GPS satellites and the own apparatus position data. A plurality of GPS satellites (visible satellites) that can be received are predicted (determined) as candidate satellites for receiving GPS signals (step S12).

  Then, the elevation angles of the plurality of candidate satellites predicted in step S12 are calculated (step S13). FIG. 10 shows the elevation angle θ between the timepiece device 100 and the GPS satellite A1. For example, as shown in FIG. 10, the elevation angle is an angle θ from the horizontal axis between the timepiece device 100 and the GPS satellite A1, and it is preferable that the elevation angle θ is close to 90 degrees because GPS signals can be received satisfactorily. This is because if the elevation angle θ is small, the GPS signal is easily affected by the troposphere and noise. For example, each elevation angle is calculated based on the current position data of a plurality of candidate satellites and the own apparatus position data among all the GPS satellites calculated in step S12.

  Then, the satellite number for identifying the candidate satellite predicted in step S12 and the elevation angle calculated in step S13 are associated with each other and stored in the RAM 13 (step S14). In step S <b> 14, the satellite number is referenced from the storage unit 15, and among the satellite numbers, the satellite number corresponding to the predicted candidate satellite and the elevation angle corresponding thereto are stored in the RAM 13.

  Then, one unselected GPS satellite having the largest elevation angle is selected from the GPS satellites (candidate satellites) having the satellite numbers stored in the RAM 13 (step S15). The satellite number selected in step S15 is stored in the RAM 13 as one satellite number.

  Then, the C / A code of the GPS satellite selected in step S15 is read from the ROM 16 (step S16). In step S16, among the C / A codes of all GPS satellites stored in the ROM 16, the C / A code of the GPS satellite corresponding to one satellite number is read out. Then, an autocorrelation value between the C / A code of the GPS satellite read in step S16 and the C / A code of the GPS signal received via the receiving unit 22 is calculated (step S17).

  Then, based on the autocorrelation value calculated in step S17, it is determined whether or not the two C / A codes match (step S18). If they match (step S18; YES), it is determined whether or not GPS signal navigation data is being received from the selected GPS satellite, and whether or not HOW data has been received from the navigation data of the GPS signal being received (step S18). S19). If no HOW data has been received (step S19; NO), the process proceeds to step S19.

  When the HOW data is received (step S19; YES), the own device position data, the internal processing time, and the leap second data are read from the storage unit 15, and the position data of the GPS satellite being received and the own device calculated in step S12 are read. Based on the position data, the distance between the GPS satellite being received and its own device is calculated, and based on the HOW data received in step S19, the distance, the internal processing time, and the leap second data, Correction data is calculated (step S20). The amount of time correction based on the distance between the receiving GPS satellite and the device itself is about 70 ms. The correction amount of the internal operation time of the timepiece device 100 is about 30 ms. The correction amount for leap seconds is 14 s. In this case, the correction amount is about 14.1 s in total, and correction data corresponding to this correction amount is obtained.

  Then, based on the correction data calculated in step S20, the internal time data of the timer unit 17 is corrected (step S21), and the first time correction process is completed.

  If they do not match (step S18; NO), the satellite number stored in the RAM 13 is referred to and it is determined whether there is an unselected candidate satellite (step S22). If there is an unselected candidate satellite (step S22; YES), the process proceeds to step S15. When there is no unselected candidate satellite (step S22; NO), the time correction error is displayed on the display unit 14 (step S23), and the first time adjustment process is terminated.

  As described above, according to the present embodiment, since one GPS satellite is selected and the HOW data of the GPS signal is received and acquired, the internal time data can be corrected using this HOW data, and the consumption in this internal time correction Since power can be reduced and one GPS satellite with a high elevation angle is selected and GPS signal HOW data is received and acquired, using HOW data from GPS satellites with a high elevation angle that is less susceptible to troposphere and noise The internal time can be corrected with high accuracy.

  Further, the elevation angle can be calculated using the almanac data, the own device position data, and the internal time data.

  Further, correction data is calculated based on the HOW data, the distance between the received GPS satellite and the clock device 100, the internal processing time, and the leap second data, and the internal time is corrected with higher accuracy using the correction data. be able to.

  The description in the above embodiment is an example of the timepiece device and the time correction method according to the present invention, and the present invention is not limited to this.

  For example, in the timepiece device 100, the position measurement is not performed using the GPS signal, and the reception unit 22 has one reception channel. However, the present invention is not limited to this. For example, the receiving unit 22 may be configured to have a plurality of receiving channels, or may be configured to be able to perform position measurement by simultaneously driving three or more receiving channels. Even in this case, when time adjustment is performed, only one reception channel needs to be driven, and power saving can be realized as compared with the case of driving a plurality of channels. Furthermore, it is good also as a structure which integrates a timepiece device in the GPS receiver which measures a position.

  Moreover, in the said embodiment, although it was set as the structure which calculates an elevation angle using almanac data, an own apparatus position data, and internal time data, it is not limited to this, Other information is used. The elevation angle may be calculated.

  In addition, it is needless to say that the detailed configuration and detailed operation of each component of the timepiece device 100 in the above embodiment can be appropriately changed without departing from the gist of the present invention.

It is a block diagram which shows the structure of the timepiece apparatus 100 of embodiment which concerns on this invention. (A) is a figure which shows the memory structure of ROM16. FIG. 2B is a diagram illustrating a storage configuration of the storage unit 15. (C) is a diagram showing a storage configuration of the RAM 13. It is a figure which shows the format of navigation data. (A) is a figure which shows the frame structure of navigation data. (B) is a figure which shows the sub-frame structure of navigation data. It is a figure which shows schematic structure of a sub-frame. It is a figure which shows the content of the sub-frame 1. It is a figure which shows the content of the sub-frame containing almanac data. It is a figure which shows the content of the page 18 of the sub-frame 4. It is a flowchart which shows a time correction process (outline). It is a flowchart which shows a 1st time correction process. It is a figure which shows the elevation angle (theta) of the timepiece apparatus 100 and GPS satellite A1.

Explanation of symbols

100 Clock Device 10 Main Body 11 CPU
12 Operation unit 13 RAM
14 Display unit 15 Storage unit 16 ROM
17 Timekeeping unit 20 Reception unit 21 Signal processing CPU
22 Receiver 23 RAM
24 ROM

Claims (6)

Receiving means for receiving one navigation data among navigation data of GPS signals transmitted from a plurality of GPS satellites;
A timekeeping means that keeps the current time as internal time data,
GPS satellite determining means for determining a plurality of GPS satellites capable of receiving the navigation data;
An elevation angle calculating means for calculating the elevation angles of a plurality of GPS satellites determined by the GPS satellite determining means;
GPS satellite selection means for selecting any one of a plurality of GPS satellites capable of receiving navigation data based on the elevation angle calculated by the elevation angle calculation means and having a high elevation angle;
Obtaining means for causing the receiving means to receive navigation data from a GPS satellite selected by the GPS satellite selecting means, and obtaining GPS time data included in the navigation data;
Internal time correction means for correcting the internal time data based on the GPS time data acquired by the acquisition means;
A timepiece device comprising: It further comprises storage means for storing GPS satellite orbit information and its own device position data,
The GPS satellite determining means selects a plurality of GPS satellites capable of receiving the navigation data based on orbit information stored in the storage means, position data of the device itself, and internal time data held in the time measuring means. Decide
2. The timepiece according to claim 1, wherein the elevation angle calculation unit calculates elevation angles of the plurality of determined GPS satellites based on the orbit information, the position data of the device itself, and the internal time data. apparatus.   The internal time correction means calculates correction data based on the GPS time data acquired by the acquisition means, the distance between the GPS satellite and the device received by the reception means, the internal processing time, and the leap second. The timepiece device according to claim 1, wherein the internal time data is corrected by the correction data. A GPS satellite determination step for determining a plurality of GPS satellites capable of receiving navigation data of GPS signals;
An elevation angle calculation step of calculating the elevation angles of a plurality of GPS satellites determined by the GPS satellite determination step;
Based on the elevation angle calculated by the elevation angle calculation step, a selection step of selecting any one of the plurality of GPS satellites capable of receiving navigation data and having a high elevation angle;
An acquisition step of receiving one navigation data corresponding to the GPS satellite selected by the selection step among the navigation data transmitted from a plurality of GPS satellites, and acquiring GPS time data included in the navigation data;
Based on the GPS time data acquired by this acquisition step, the internal time correction step of correcting the internal time data held in the time measuring means,
A time correction method comprising: In the GPS satellite determination step, a plurality of GPS satellites capable of receiving the navigation data are determined based on the orbit information of the GPS satellites stored in the storage means, the position data of the own device, and the internal time data,
5. The time according to claim 4, wherein, in the elevation angle calculation step, the elevation angles of the plurality of determined GPS satellites are calculated based on the orbit information, the position data of the device itself, and the internal time data. How to fix.   In the internal time correction step, correction data is calculated based on the GPS time data acquired in the acquisition step, the distance between the GPS satellite and the device received in the acquisition step, the internal processing time, and the leap second. 6. The time correction method according to claim 4, wherein the internal time data is corrected by the correction data.

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