JP2011038989A - Electronic timepiece - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electronic timepiece that rapidly acquires time information and suppresses power consumption. <P>SOLUTION: A watch having a GPS is equipped with: a GPS reception section 10 for capturing satellite signals from a GPS satellite, receiving the captured satellite signals, and acquiring information based on the received satellite signals; a time display device 20 for displaying and controlling the acquired information; a reception mode setting section 215 for switching between a time measurement mode for acquiring time information included in satellite signals and a position measurement mode for computing the position of the electronic watch by acquiring position information included in the satellite signals; and a threshold setting section 15 for setting an initial value of a signal reception threshold to an upper-limit value in the position measurement mode, reducing the signal reception threshold to a prescribed lower-limit value in steps according to a correlation count, and fixing the signal reception threshold to a lower-limit value in the time measurement mode. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an electronic timepiece that receives a satellite signal from a position information satellite such as a GPS satellite and obtains the current date and time.

  In a GPS (Global Positioning System) system that is a system for positioning its own position, a GPS satellite having an orbit around the earth is used, and a satellite signal from the GPS satellite is received and included in the satellite signal. GPS devices that implement time correction processing and processing for positioning the current position based on time information and position information that have been put into practical use have been put into practical use.

  In capturing a satellite signal transmitted from a GPS satellite, a correlation value or signal intensity is given a threshold value, and a satellite signal having a signal level equal to or higher than the threshold value is received to determine whether or not subsequent synchronization processing and NAV data decoding processing are possible. . As a result, it is possible to receive a high-quality radio wave signal that is less affected by noise and the like, and it is possible to improve positioning accuracy and date / time correction accuracy (see, for example, Patent Document 1).

  When receiving a satellite signal of a high elevation satellite, the GPS receiver described in Patent Document 1 stores the received signal level of the satellite in a memory, and when the data stored in the memory exceeds a predetermined number, these data are stored. The average value (moving average) of is calculated. Then, the GPS receiving apparatus refers to the table data indicating the correspondence relationship of the optimum threshold value to the received signal level, sets the optimum threshold value for the moving average, and eliminates the satellite signal and multipath of the low elevation satellite. It has been.

JP 2003-149315 A

By the way, in the GPS receiver, when performing the positioning calculation for obtaining the current position based on the position information included in the satellite signal, a long-time reception process is required to acquire the position information having a large data size. It is also necessary to acquire at least three pieces of highly reliable information. For this reason, it is preferable to receive a satellite signal having a high signal intensity from a high elevation satellite.
On the other hand, an electronic timepiece that obtains only time information from a satellite signal and corrects the time does not necessarily require a satellite signal having a high signal intensity that is necessary for positioning calculation. That is, the time information included in the satellite signal has a data size smaller than that of the position information, and the time required to acquire the time information may be shorter than that during the positioning calculation. Even when a noise component is included, since the influence of noise on the time information is sufficiently small, the time information can be acquired with a satellite signal having a signal intensity lower than that at the time of positioning calculation. That is, time information can be acquired even for a satellite signal having a low signal intensity, such as a satellite signal from a GPS satellite located at a low elevation angle or a multipath satellite signal.

  However, the GPS receiver as in Patent Document 1 receives only satellite signals from high elevation satellites and cuts satellite signals from low elevation satellites and multipath satellite signals based on the optimum threshold. . Therefore, if the GPS receiver is in a poor reception environment where satellite signals from high elevation satellites cannot be received, such as indoors or near buildings, it is assumed that satellite signals from multi-path satellites from low elevation satellites that can acquire time information. Even when a satellite signal is input, there is a problem that time information cannot be acquired.

  In addition, the GPS receiver can reduce the signal strength threshold of receivable satellite signals according to the elapsed time so that satellite signals that could not be received at the start of reception can be received after a predetermined time has elapsed. Some devices do this. However, in this case, there is a problem that the time from the start of reception to the acquisition of information becomes long, resulting in an increase in power consumption. In particular, in a small electronic timepiece such as a wristwatch, there is a limit to the power to be supplied. Therefore, it is not preferable in terms of power consumption to perform such a long-time reception process.

  In view of the above problems, an object of the present invention is to provide an electronic timepiece that can quickly acquire time information and suppresses power consumption.

  The electronic timepiece of the present invention performs a search process for searching for a satellite signal that can be captured from satellite signals transmitted from a plurality of position information satellites, and among the satellite signals captured by the search process, the signal strength is a predetermined signal. A receiving unit that receives a satellite signal that is equal to or greater than a reception threshold; an information acquiring unit that acquires predetermined information based on the satellite signal received by the receiving unit; a display unit that displays the acquired information; and the information acquiring unit A time measuring mode for acquiring time information included in the satellite signal, and a mode switching means for switching a positioning mode for acquiring position information included in the satellite signal by the information acquiring means and calculating the position of the electronic timepiece; , Threshold setting means for setting the signal reception threshold according to the mode switched by the mode switching means, the threshold setting means A search that is the number of times that the search processing is performed on the satellite signals of all position information satellites while setting the initial value of the signal reception threshold to a predetermined positioning threshold when switched to the positioning mode. The signal reception threshold is decreased stepwise according to the number of times, and when the mode is switched to the timing mode, the signal reception threshold is less than the positioning threshold and becomes a predetermined lower limit or more. The threshold value is set.

  Here, when the search process (correlation process) is performed on the satellite signals of all the position information satellites, the time required for the correlation process (correlation required time) is substantially determined. Therefore, in the positioning mode, the threshold setting means may count the number of correlations, and may perform a process of decreasing the signal reception threshold every time the predetermined number of correlations is counted. You may perform the process which decreases a signal reception threshold for every time required for the correlation process of the predetermined | prescribed correlation frequency | count.

In the present invention, the electronic timepiece can switch between the positioning mode for measuring the position and the time measuring mode for acquiring the time information by the mode switching means, and the threshold setting means can change the satellite signal according to these modes. The signal reception threshold when receiving is set.
That is, in the positioning mode, the position information (orbit information) of the position information satellite signal is acquired from at least three or more satellite signals, and the process of calculating the position based on the information is performed, so only the time information is extracted. Compared to the timekeeping mode, more accurate information is required. Therefore, in satellite signal reception in the positioning mode, a high-level positioning threshold is set as the initial value of the signal reception threshold. Then, when the satellite signal is not captured with the positioning threshold, the signal reception threshold is decreased stepwise according to the number of correlations. As a result, satellite signals with high signal strength can be preferentially captured, and appropriate position calculation processing can be performed.

On the other hand, in the timekeeping mode, only time information needs to be acquired from the transmitted satellite signal. In such a case, a highly accurate satellite signal as in the positioning mode is not required, and it is possible to sufficiently acquire time information even for a satellite signal having a weak signal intensity and including a noise component. Therefore, the satellite signal from any position information satellite may be received as long as it is a satellite signal having a signal intensity capable of acquiring time information.
For this reason, in the present invention, in the time measurement mode, the threshold value setting means sets and fixes a time measurement fixed threshold value that is less than the positioning threshold value and is equal to or greater than a predetermined lower limit value. Here, the lower limit value is the lowest signal intensity at which information can be acquired from the acquired satellite signal, and a satellite signal having a signal intensity smaller than this lower limit value has a lot of noise components, etc., and acquires accurate information. It becomes difficult.
By setting such a fixed threshold for time measurement, the time from the start of reception to the completion of reception in the time measurement mode can be shortened. In other words, when a satellite signal having a signal strength that is greater than or equal to the fixed threshold for time measurement and less than the threshold for positioning is input to the electronic timepiece, the reception processing in the time measurement mode is performed with the same fixed time threshold for positioning In this case, the satellite signal is not captured at the start of reception. For example, the satellite signal can be captured after the signal reception threshold is decreased by performing a predetermined correlation process. In contrast, in the timekeeping mode, the signal reception threshold is fixed to the timekeeping fixed threshold smaller than the positioning threshold, so that any satellite signal whose signal intensity is equal to or greater than the timekeeping fixed threshold is captured. be able to. Therefore, as described above, when a satellite signal having a signal strength that is greater than or equal to the fixed timing threshold and less than the positioning threshold is input, the satellite signal can be captured from the start of reception. As a result, the time required for capturing the satellite signal is shortened, and the time until the completion of the acquisition (decoding process) of the time information by the information processing means is shortened. Therefore, in the time measurement mode, the power consumption required for the satellite signal reception operation is also reduced, and the battery voltage can be maintained for a long time. Moreover, since the power drop of the battery voltage can be suppressed, the system down due to the voltage drop can also be prevented.

  The electronic timepiece of the invention includes input means capable of inputting setting information for switching to either one of the positioning mode and the timekeeping mode, and the mode switching means receives the setting from the input means. When information is input and the satellite signal is received, the mode is switched to either the timekeeping mode or the positioning mode based on the setting information, and the satellite signal is received at a predetermined time. When the time setting mode is switched to the timekeeping mode, the threshold setting means is used for timekeeping that is smaller than the positioning threshold and larger than the lower limit value when the time setting mode is switched. When a fixed threshold is set and the mode is switched to the automatic timing mode, the signal reception threshold is preferably set to the lower limit value.

In the present invention, the mode switching means switches between the manual mode and the automatic timekeeping mode depending on whether or not the setting information is input by the operation of the input means by the user. The manual mode includes the positioning mode and the timekeeping mode, and is switched as appropriate based on setting information. The automatic timekeeping mode is a mode that is set when setting information is not input from the input means and automatically acquires time information on time. Then, when the mode is switched to the automatic timing mode by the mode switching unit, the threshold setting unit sets and fixes a lower limit value as the signal reception threshold.
When receiving a satellite signal, a satellite signal having a low signal strength includes a large amount of noise components, and thus information acquisition processing (decoding processing) by the information processing means may take a long time. In addition, when performing processing in the timekeeping mode (timekeeping processing) in the manual mode, it is conceivable that the user intentionally maintains the electronic timepiece at a good position in the reception environment. Therefore, in the manual mode, it is expected that a satellite signal having a relatively large signal strength is input to the electronic timepiece. Here, when the signal reception threshold is set to the lower limit value, a satellite signal having a low signal strength is also captured, and the user may wait for a long time until the processing is completed.
On the other hand, in the manual timekeeping mode as in the present invention, the signal strength is extremely high, for example, a satellite signal having a signal strength substantially equal to the lower limit value by making the fixed threshold for timekeeping larger than the lower limit value. Small satellite signals can be excluded, and the time measurement process can be completed more quickly.
On the other hand, the automatic timekeeping mode is a timekeeping process that is performed on time regardless of the user's intention, and does not make the user wait even if the reception time is long. Further, when the electronic timepiece is indoors, for example, at night, the reception environment may be poor and only the signal intensity near the lower limit value may be captured. Therefore, by setting the signal reception threshold value to the lower limit value in the automatic timekeeping mode, time information can be acquired even in a poor reception environment such as indoors.

  In the electronic timepiece of the invention, when the mode switching unit is switched to the timekeeping mode, a normal timekeeping mode in which only the time information is acquired, date information included in the satellite signal, and When switching to the detailed time measurement mode for acquiring the time information, the threshold value setting means sets the signal reception threshold value to the time measurement fixed threshold value when the normal time measurement mode is switched, and the details When the mode is switched to the timekeeping mode, the signal reception threshold is preferably set to a second timekeeping fixed threshold that is smaller than the positioning threshold and larger than the timekeeping fixed threshold.

When a GPS satellite is used as a position information satellite, the GPS satellite transmits a satellite signal composed of six subframes at intervals of 30 seconds, and each subframe 1 to 6 is transmitted at intervals of 6 seconds. . Here, the time information is information included in each subframe, and the date information is information included only in subframe 1. That is, time information is transmitted at intervals of 6 seconds, and date information is transmitted at intervals of 30 seconds. Therefore, when only the time information is received, even if the satellite signal has a low signal intensity and the information cannot be acquired due to a noise component or the like, the information acquisition can be attempted again by the subframe transmitted after 6 seconds. On the other hand, since the date information is transmitted at intervals of 30 seconds, it is necessary to wait for the transmission of subframe 1 after 30 seconds when information cannot be acquired due to a noise component or the like with a satellite signal having a low signal strength. There is. Therefore, in the detailed time measurement mode, when information is acquired from a satellite signal having a low signal strength, the reception time may be long.
Here, in the present invention, in the detailed time measurement mode, there is a second time measurement fixed threshold value that is larger than the time measurement fixed threshold value set in the normal time measurement mode in which only time information is acquired and smaller than the positioning threshold value. Used. For this reason, even in the detailed time measurement mode, satellite signals with high signal strength can be preferentially received, and the inconvenience of a long reception time due to failure to obtain date information can be prevented.

  In the electronic timepiece according to the aspect of the invention, the receiving unit stops the search process when a predetermined number of satellite signals are acquired or a satellite signal having a predetermined signal strength or higher is acquired in the timekeeping mode. It is preferable.

Here, the predetermined number is an integer of 2 or more. In the time measurement mode, if the time information can be acquired from one satellite signal, the time can be corrected based on the acquired information. However, when acquiring information by capturing only one satellite signal with a low signal strength, it may be difficult to acquire information if the signal strength drops due to changes in the reception environment. May fail. In addition, when the satellite signal search process is continuously performed until the time information acquisition is completed, there is a problem that power consumption increases.
On the other hand, if the search process is stopped after acquiring a predetermined number of satellite signals as in the present invention, the signal strength of any one of these satellite signals drops, and the decoding process is difficult. Even in such a case, information can be acquired by other satellite signals. As a result, even when only a satellite signal having a low signal strength can be captured by the receiving means, a stable receiving operation can be performed, and the receiving time can be shortened. In addition, since the search process is stopped in a state where a predetermined number of satellite signals are captured, the power consumption required for the search process can be suppressed.
On the other hand, in the case where only the condition for stopping the search process after capturing a predetermined number of satellite signals is obtained, only one satellite signal with a high signal strength is captured, and the search process continues even when other satellite signals cannot be captured. Therefore, the power consumption may increase. On the other hand, in the present invention, the search process is stopped even when a satellite signal having a signal strength equal to or higher than a predetermined signal strength is acquired. That is, if a satellite signal having a high signal strength can be received, time information can be received early even if a predetermined number of satellite signals cannot be received. In addition, when a satellite signal with a signal intensity equal to or higher than a predetermined value is captured, the search process is stopped, so that power consumption can be suppressed.
As described above, by stopping the search processing based on the number of captured satellite signals and the signal strength of the captured satellite signals, the satellite signals can be stably received and the receiving operation can be performed more quickly. It can be implemented and power consumption can be reduced.

  Here, the electronic timepiece of the present invention includes a solar cell that receives light to generate power, and a power generation amount detecting unit that detects a power generation amount in the solar cell, and the receiving unit is configured to perform the measurement in the timekeeping mode. When the fluctuation value of the power generation amount detected by the power generation amount detection means is a predetermined value or more, even when a predetermined number of satellite signals are captured, or even when a satellite signal having a predetermined signal strength or more is captured, the information The search process may be continued until the time information is acquired by the acquisition means.

In the present invention, as described above, the search process is stopped based on the number of captured satellite signals and the signal strength of the captured satellite signals. At this time, the amount of power generated by the solar cell fluctuates by a predetermined value or more. If so, the search process is continued. Here, in a state where the amount of power generated by the solar cell fluctuates, it is possible that the user is walking with the electronic watch worn on his arm. In such a situation, for example, the user is in the shadow of the building. In some cases, the reception environment may deteriorate. In such a case, if the search process is stopped as described above, even if the satellite signal is captured, the radio wave may be interrupted during information acquisition and the reception operation may be stopped. There are cases where the reception process cannot be performed and the reception time becomes longer.
In the present invention, it is possible to easily determine whether or not the user is walking based on the fluctuation value of the power generation amount in the solar cell detected by the power generation amount detection means. And when the fluctuation amount of the electric power generation amount in a solar cell is more than predetermined value, and it is judged that the user is walking, a receiving means continues search processing. As a result, even if the reception environment changes due to the movement of the user, the signal strength of the already acquired satellite signal drops and the reception operation becomes impossible, the search process searches for another satellite signal with a higher signal strength. Can be captured. Therefore, even when the user is walking, inconvenience such as reception failure can be prevented by continuously searching for receivable satellite signals.

  An electronic timepiece according to the present invention includes an internal clock unit that counts time, and a time correction unit that corrects the time counted by the internal clock unit based on the time information acquired by the information acquisition unit. And the time correction means, when the time difference between the time of the time information acquired by the information acquisition means and the time of the internal timekeeping unit is less than or equal to a predetermined value in the timekeeping mode, It is preferable to correct the time of the internal timing unit based on the information.

  In the present invention, the time correction means corrects the time of the internal timekeeping part to the time of the time information only when the difference between the time of the time information acquired from the satellite signal and the time counted by the internal timekeeping part is large. . Here, the internal timekeeping unit continuously counts the time except when the remaining power of the battery runs out or when the initialization process is performed. The difference between the time counted by the internal timekeeping unit and the current time becomes very small. Therefore, when the time of the internal timekeeping part is periodically corrected, the difference between the time of the internal timekeeping part and the time acquired from the satellite signal is also a small value. For this reason, when the difference between the time of the internal timekeeping unit and the time of the time information included in the satellite signal is equal to or greater than a predetermined value, the time information includes a noise component, and thus the accurate time cannot be obtained In such a case, the time adjustment means does not correct the time of the internal timekeeping unit. Accordingly, it is possible to prevent the inconvenience that the time of the internal timekeeping unit is set to an incorrect time due to the incorrect time information, and the incorrect time is displayed by the display means.

  An electronic timepiece according to the present invention includes an internal time counting unit that counts time and time, and a time correcting unit that corrects the time counted by the internal time measuring unit based on the time information acquired by the information acquiring unit. The time adjustment means includes two or more satellite signals captured by the reception means in the timekeeping mode, and the signal strength of these captured satellite signals is higher than a predetermined signal strength. If the time information obtained from these satellite signals is substantially the same and the time difference between the time information and the time of the internal timekeeping unit is less than or equal to a predetermined value, It is good also as a structure which corrects the time of the said internal time measuring part based on the said time information.

In the present invention, as described above, the time of the internal timekeeping unit is compared with the time of the time information. At this time, the time correcting means captures two or more satellite signals and captures these captured satellite signals. When the time information acquired from each coincides and the difference between the time of the matched time information and the time of the internal timekeeping unit is within a predetermined value, the time of the internal timekeeping unit is corrected.
That is, in two or more satellite signals, the possibility of noise entering at the same position on the data is small. Therefore, when the time information of these satellite signals matches, a highly reliable time with no noise component included It can be judged as information. Therefore, the time correction means can perform highly reliable time correction by correcting the time of the internal clock unit when the time information of two or more satellite signals match. On the other hand, even when the time information of two or more satellite signals match, if noise enters the same position on the data, it is difficult to set an accurate time using these time information. Even in this case, the time correction means calculates the difference between the time of the internal timekeeping portion and the time of the time information, and only when the difference is within a predetermined value, the time adjustment means calculates the time of the internal timekeeping portion. Correct it and prevent it from being corrected at the wrong time.
As described above, more reliable time correction can be performed.

It is the schematic which shows the wristwatch with GPS which is the electronic timepiece of 1st Embodiment which concerns on this invention. It is a schematic block diagram for demonstrating the structure of the satellite signal (navigation message) transmitted from a GPS satellite. It is a figure for demonstrating the circuit structure of the wristwatch 1 with GPS of the said embodiment. It is a flowchart which shows the reception process of the satellite signal of the wristwatch with GPS of the said embodiment. It is a flowchart which shows the reception operation | movement of the positioning mode in the reception process of the satellite signal of the wristwatch with GPS of the said embodiment. It is a flowchart which shows the reception operation | movement of the timekeeping mode in the reception process of the satellite signal of the GPS wristwatch of the embodiment. It is a figure which compares the signal reception state in the timekeeping mode of the said embodiment, and the signal reception state in a comparative example. It is a figure which shows the relationship between the signal strength of the timekeeping mode in the said embodiment and a comparative example, and the time required until time information acquisition. It is a figure which shows the signal reception threshold set in each mode of the wristwatch with GPS of 2nd Embodiment. It is a figure which shows the signal reception threshold set in each mode of the wristwatch with GPS of 3rd Embodiment.

[First Embodiment]
Hereinafter, a first embodiment of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a schematic view showing a wristwatch 1 with a GPS satellite signal receiving device (hereinafter referred to as “GPS wristwatch 1”) which is an electronic timepiece according to the present invention.
As shown in FIG. 1, the GPS wristwatch 1 includes display means including a dial 2 and hands 3. An opening is formed in a part of the dial plate 2, and a display 4 composed of an LCD display panel or the like is incorporated. Therefore, the GPS wristwatch 1 is a combination watch including the hands 3 and the display 4.

The pointer 3 includes a second hand, a minute hand, an hour hand, and the like, and is driven by a step motor through a gear.
The display 4 is composed of an LCD display panel or the like, and displays time difference data as will be described later, as well as the current time and message information.
The GPS wristwatch 1 receives satellite signals from a plurality of GPS satellites 5 orbiting the earth in a predetermined orbit to acquire satellite time information, correct internal time information, or position information. That is, the current position can be displayed on the display 4.
Further, the GPS wristwatch 1 is provided with a button 6 and a crown 7 which constitute the input means of the present invention.

  The GPS satellite 5 (5a, 5b, 5c, 5d) orbits a predetermined orbit above the earth, and transmits a navigation message superimposed on a 1.57542 GHz microwave (Ll wave) to the ground. Yes. Here, the GPS satellite 5 is an example of a position information satellite in the present invention, and a 1.57542 GHz microwave (hereinafter referred to as “satellite signal”) on which a navigation message is superimposed is an example of a satellite signal in the present invention.

  Currently, about 30 GPS satellites 5 exist, and in order to identify which GPS satellite 5 the satellite signal is transmitted from, each GPS satellite 5 is 1023 chip called a C / A code (Coarse / Acquisition Code). A unique pattern of (1 ms period) is superimposed on the satellite signal. The C / A code looks like a random pattern with each chip being either +1 or -1. Therefore, by correlating the satellite signal and the pattern of each C / A code, the C / A code superimposed on the satellite signal can be detected.

Here, an outline of a satellite signal (navigation message) transmitted from the GPS satellite 5 will be described.
2A to 2C are schematic configuration diagrams for explaining the configuration of a satellite signal (navigation message) transmitted from the GPS satellite 5. FIG.
As shown in FIG. 2 (A), the navigation message is configured as data with a main frame having a total number of 1500 bits as one unit. The main frame is divided into five sub-frames 1 to 5 each having 300 bits. Data of one subframe is transmitted from each GPS satellite 5 in 6 seconds. Accordingly, data of one main frame is transmitted from each GPS satellite 5 in 30 seconds.

Subframe 1 includes satellite correction data such as week number data. The week number data (year / month / day information) is year / month / day information representing a week including the current GPS time information. The starting point of the GPS time information is January 6, 1980, 00:00:00 in UTC (Coordinated Universal Time), and the week starting on this day is the week number 0. Week number data is updated on a weekly basis.
The subframes 2 and 3 include ephemeris parameters (detailed orbit information of each GPS satellite 5). The subframes 4 and 5 include almanac parameters (general orbit information of all GPS satellites 5).

Further, in the subframes 1 to 5, from the top, a TLM (Telemetry) word storing 30-bit TLM (Telemetry word) data and a 30-bit HOW (hand over word) are stored.
) A HOW word in which data is stored is included.
Accordingly, TLM words and HOW words are transmitted from the GPS satellite 5 at intervals of 6 seconds, whereas satellite correction data such as week number data, ephemeris parameters, and almanac parameters are transmitted at intervals of 30 seconds.

As shown in FIG. 2B, the TLM word includes preamble data, a TLM message, a reserved bit, and parity data.
As shown in FIG. 2C, the HOW word includes GPS time information called TOW (Time of Week, also referred to as “Z count”). The time information of the present invention refers to the Z count data included in the GPS time information. In the Z count data, the elapsed time from 0 o'clock every Sunday is displayed in seconds, and it returns to 0 at 0 o'clock on the next Sunday. That is, the Z count data is information in units of seconds indicated every week from the beginning of the week. This Z count data indicates GPS time information at which the first bit of the next subframe data is transmitted. For example, the Z count data of subframe 1 indicates GPS time information at which the first bit of subframe 2 is transmitted. The HOW word also includes 3-bit data (ID code) indicating the ID of the subframe. That is, ID codes “001”, “010”, “011”, “100”, and “101” are included in the HOW words of subframes 1 to 5 shown in FIG.

  Generally, a GPS receiver can acquire GPS time information by acquiring week number data included in subframe 1 and HOW word (Z count data) included in subframes 1 to 5. However, if the GPS receiver has previously acquired the week number data and is counting the elapsed time from the time when the week number data was acquired internally, the current GPS satellites can be acquired without acquiring the week number data. Can be obtained. Therefore, the GPS receiver can know the current time other than the date by acquiring the Z count data. For this reason, the GPS receiver normally acquires only Z count data as time information as the current time.

  The TLM word, HOW word (Z count data), satellite correction data, ephemeris parameter, almanac parameter, etc. are examples of satellite information in the present invention.

In the GPS wristwatch 1, in the timekeeping mode in which the timekeeping process is performed, it means that Z count data as time information is acquired. Z count data can also be acquired from one GPS satellite 5. Since the Z count data is included in each subframe, it is transmitted at intervals of 6 seconds.
For this reason, in the reception in the timekeeping mode, the number of captured satellites is at least one, the reception time required to acquire one piece of Z count data is at most 6 seconds, and the information that can be acquired is Z count data The ephemeris parameter and the almanac parameter may not be received. Therefore, one Z count data can be acquired in 6 seconds, and the reception time is 12 to 18 seconds in order to verify the received data even if 2 to 3 Z count data are acquired. Can be completed.
Therefore, in the timekeeping mode, it is only necessary to acquire Z count data out of the satellite signals. Therefore, even satellite signals with low signal strength are less affected by noise and the like, and highly reliable information can be acquired.

On the other hand, receiving in the positioning mode means receiving ephemeris parameters, which are orbit information of each GPS satellite 5, for at least three satellites. This is because it is necessary to acquire ephemeris parameters from at least three GPS satellites 5 for positioning. Since the ephemeris parameter is included in subframes 2 and 3, it can be acquired by performing reception for 18 seconds at the shortest (reception from subframes 1 to 3). Therefore, when capturing and receiving a plurality of GPS satellites 5 at the same time, in order to obtain positioning data by performing ephemeris parameter reception and positioning calculation, approximately 30 seconds to 1 minute in a cold start state in which no almanac data is held. I need time.
For this reason, the positioning mode reception means that the number of captured satellites is at least 3, the reception time is about 30 seconds to 1 minute, and information to be acquired is Z count data (time information) and an ephemeris parameter. The almanac parameter means a process of not receiving. Therefore, in the positioning mode, if the satellite signal reception time is longer than that in the time measurement mode and the signal strength deteriorates during reception, it may be difficult to receive a highly reliable satellite signal. For this reason, in the positioning mode, it is preferable to receive a satellite signal with higher signal strength and higher reliability.

[Circuit configuration of GPS wristwatch]
FIG. 3 is a diagram for explaining a circuit configuration of the GPS wristwatch 1 according to the first embodiment.
The GPS wristwatch 1 includes a GPS receiving unit 10 that is a receiving unit, a GPS antenna 11, a time display device 20 that is a display unit, and a power supply circuit 30.

[Configuration of GPS receiver]
A GPS antenna 11 is connected to the GPS receiver 10. The GPS antenna 11 is an antenna that receives satellite signals from a plurality of GPS satellites 5.

The GPS receiver 10 includes an RF (Radio Frequency) unit 12, a baseband unit 13, a threshold setting unit 15, and a threshold variable timing setting unit 16. The baseband unit 13 functions as a reception unit and information acquisition unit of the present invention, and the threshold setting unit 15 functions as a threshold setting unit of the present invention.
Since the RF unit 12 is the same as that in a general GPS receiver, description thereof is omitted. The RF unit 12 converts the received satellite signal into a digital signal and outputs it to the baseband unit 13.

  The baseband unit 13 includes a DSP (Digital Signal Processor) 131, a CPU (Central Processing Unit) 132, an SRAM (Static Random Access Memory) 133, and an RTC (Real Time Clock) 134. The GPS receiving unit 10 is connected to a temperature-compensated crystal oscillation circuit (TCXO: Temperature Compensated Crystal Oscillator) 14, and the baseband unit 13 is connected to a flash memory 135 and the like.

The crystal oscillation circuit with temperature compensation circuit (TCXO) 14 generates a reference clock signal having a substantially constant frequency regardless of the temperature.
The flash memory 135 stores time difference information. The time difference information is information in which the time difference of each of a plurality of areas into which geographic information is divided is defined.

The baseband unit 13 performs a process of demodulating (decoding) the baseband signal from the digital signal (intermediate frequency band signal) converted by the RF unit 12.
The baseband unit 13 generates a local code having the same pattern as each C / A code in order to capture a satellite signal, and correlates each C / A code included in the baseband signal with the local code. Process.
Then, the baseband unit 13 adjusts the local code generation timing so that the correlation value for each local code has a peak, and if the correlation value is equal to or greater than a predetermined correlation threshold, the baseband unit 13 It is determined that the signal is synchronized (that is, the satellite signal from the GPS satellite 5 is captured).

Here, the GPS system employs a CDMA (Code Division Multiple Access) system in which all GPS satellites 5 transmit satellite signals of the same frequency using different C / A codes. Therefore, by detecting the C / A code included in the received satellite signal, it is possible to search for a GPS satellite 5 that can be captured.
In the present embodiment, the sliding correlation method is adopted as the correlation method, which is mainly executed in the DSP 131.

  Further, at this time, the baseband unit 13 detects the signal strength of the received satellite signal, and performs processing for capturing the satellite signal when the signal strength is equal to or greater than a predetermined signal reception threshold. Here, the signal reception threshold is set by the threshold setting unit 15 and the threshold variable timing setting unit 16.

The threshold setting unit 15 performs a process of setting a signal reception threshold value. Here, the threshold value setting unit 15 sets a signal reception threshold value used when receiving a satellite signal according to the reception mode set by the reception mode setting unit 215 of the time display device 20 described later.
In the GPS wristwatch 1 according to the present embodiment, the reception mode setting unit 215 switches between the positioning mode, the timekeeping mode, and the automatic timekeeping mode. Here, the positioning mode and the time measurement mode are manual reception processes, and are modes that are switched by operating the button 6 as an input means and inputting predetermined setting information by the user. In the positioning mode, as described above, the Z calculation data and the ephemeris parameter are acquired from at least three satellite signals, and the positioning calculation process for calculating the current position where the GPS wristwatch 1 is positioned is performed. In the time measurement mode, as described above, only Z count data is acquired from at least one satellite signal, and time correction processing is performed based on the acquired Z count data.
On the other hand, the automatic timekeeping mode is a mode that automatically shifts to a preset time, and performs Z count data acquisition and time correction processing.

  Here, in the positioning mode, the threshold value setting unit 15 sets the initial value of the signal reception threshold value to a positioning threshold value that is preset and recorded in the flash memory 135. In the present embodiment, the positioning threshold is set to an upper limit value that can capture only the satellite signal from the high-elevation GPS satellite 5. Here, the upper limit value is a signal intensity that stabilizes the time (reception time) required to capture the satellite signal from the start of the reception process and decode the captured satellite signal, and is, for example, “−134 dBm”. Is set. That is, when the signal reception threshold is set to “−134 dBm”, a satellite signal having a signal strength of “−134 dBm” or more can be captured. The reception time of such a satellite signal is a substantially constant value of about 30 seconds to about 40 seconds, and stable satellite signal reception is possible. On the other hand, in a satellite signal having a signal reception threshold value smaller than “−134 Bm”, the decoding process takes time due to an increase in noise components. For example, when “−136 dBm” is set, the reception time is about 70 seconds. It becomes. Therefore, by setting “−134 dBm” as the upper limit value of the signal reception threshold, it is possible to preferentially receive a highly reliable satellite signal with few noise components.

In the positioning mode, the threshold setting unit 15 performs a threshold reduction process for reducing the signal reception threshold according to the number of correlations (search number) counted by a threshold variable timing setting unit 16 described later. In the present embodiment, every time the number of correlations by the threshold variable timing setting unit 16 becomes “3” in a state where three or more satellite signals necessary for the positioning calculation cannot be captured, the signal reception threshold is set stepwise. Process to decrease by a predetermined amount. The decrease range of the threshold may be set as appropriate. However, if the decrease range is increased, the time until satellite signal acquisition and reception is completed can be further shortened. If the decrease range is decreased, a plurality of satellite signals are decreased. Therefore, it is possible to appropriately acquire a satellite signal having a high signal intensity.
For example, the flash memory 135 stores a lower limit value of the signal reception threshold value. When the signal reception threshold value is reduced to the lower limit value, no further threshold reduction process is performed. Then, after the signal reception threshold is reduced to the lower limit value, when the predetermined number of correlations (three times in the present embodiment) is counted by the threshold variable timing setting unit 16, the threshold setting unit 15 again transmits the signal A threshold value reduction process is performed in which the reception threshold value is set to an upper limit value and the signal reception threshold value is decreased according to the number of correlations. Also, the GPS receiver 10 could not acquire information from, for example, three or more satellite signals based on the signal reception threshold after a predetermined number of correlations or a predetermined time from the start of the satellite signal reception operation. In this case, it is determined that a timeout has occurred, and the satellite signal reception process is stopped.
Here, the lower limit value is the lowest signal intensity at which information can be acquired from the satellite signal, and is set to “−142 dBm”, for example. A satellite signal having a signal strength smaller than this lower limit value has many noise components, making it difficult to obtain accurate information.

  On the other hand, when the reception mode setting unit sets the timekeeping mode and the automatic timekeeping mode, the threshold setting unit 15 sets the signal reception threshold to a timekeeping fixed threshold smaller than the positioning threshold (upper limit value). Set. In the present embodiment, the lower limit value is set as the time measurement fixed threshold. In the timekeeping mode and the automatic timekeeping mode, the threshold setting unit 15 fixes the signal reception threshold to the timekeeping fixed threshold (lower limit) during the satellite signal reception process.

The threshold variable timing setting unit 16 counts the number of times correlation processing has been performed by the baseband unit 13 and outputs a signal notifying the timing at which the threshold variable unit performs threshold reduction processing for each predetermined number of correlations. Here, the correlation process is a process of searching for which satellite is the GPS satellite 5 corresponding to the input satellite signal using the C / A code, and corresponds to the search process of the present invention. Corresponds to the number of times this search process has been performed, that is, the number of searches of the present invention.
Specifically, the threshold variable timing setting unit 16 sets the number of correlations to “1” when each process of correlating the input satellite signal with the local codes 1 to 30 is performed once. Count.
The threshold variable timing setting unit 16 may be configured to count the number of times of correlation by counting the time required for the number of times of correlation to be “1” because the time for performing the correlation is constant.

  Furthermore, the baseband unit 13 demodulates (decodes) the navigation message by mixing a local code having the same pattern as the C / A code of the captured GPS satellite 5 and the baseband signal, and orbit information included in the navigation message. And satellite information such as GPS time information is acquired and stored in the SRAM 133.

  The trajectory information and GPS time information included in the navigation message are examples of position information and time information in the present invention, and the GPS receiver 10 functions as a receiver in the present invention. In addition, since the baseband unit 13 of the GPS receiving unit 10 acquires position information and time information, it also functions as an information acquisition unit in the present invention.

  The operation of the baseband unit 13 is synchronized with the reference clock signal output from the crystal oscillator circuit with temperature compensation circuit (TCXO) 14. The RTC 134 generates timing for processing satellite signals. The RTC 134 is counted up by a reference clock signal output from a crystal oscillation circuit (TCXO) 14 with a temperature compensation circuit.

[Configuration of time display device]
The time display device 20 includes a control unit 21 and a crystal resonator 22.

  The control unit 21 includes an internal clock unit 211, an oscillation circuit 212, drive circuits 213 and 214, a reception mode setting unit 215 as a mode switching unit, a capture operation control unit 216, and a decode processing control unit 217, and performs various controls. .

The internal timekeeping unit 211 counts and stores internal time information. This internal time information is information on the time measured inside the GPS wristwatch 1. The internal timekeeping unit 211 updates the internal time information with the reference clock signal generated by the crystal resonator 22 and the oscillation circuit 212. Therefore, even if the power supply to the GPS receiving unit 10 is stopped, the internal time information can be updated and the hand movement of the hands 3 can be continued.
The drive circuit 213 controls the operation of the pointer 3. The drive circuit 214 controls display on the display 4.
As described above, the reception mode setting unit 215 sets the reception mode to either the positioning mode or the time measurement mode when the user operates the button 6 or the like, and the setting input from the button 6 or the like is performed. If not, the reception mode is set to the automatic timing mode at a preset time.

The capture operation control unit 216 and the decode processing control unit 217 control the GPS receiving unit 10 to execute reception processing. That is, the capturing operation control unit 216 sends a control signal to the GPS receiving unit 10, controls the receiving operation of the GPS receiving unit 10, and particularly controls the operation of capturing a satellite signal.
The decoding process control unit 217 also controls the receiving operation of the GPS receiving unit 10, and in particular controls the decoding process in the baseband unit 13.

The capturing operation control unit 216 and the decoding process control unit 217 constitute time correction means of the present invention. That is, the capture operation control unit 216 and the decoding process control unit 217 control the operation of the GPS reception unit 10 when the reception mode is the time measurement mode or the automatic time measurement mode, and include the GPS time including the Z count data from the satellite signal. Information is acquired, the internal time information is corrected based on the GPS time information, and the internal time information counted by the internal timekeeping unit 211 is updated.
At this time, the capture operation control unit 216 and the decode processing control unit 217 calculate a time difference between the GPS time based on the Z count data of the acquired GPS time information and the internal time counted by the internal time measuring unit 211, and If the time difference is within a predetermined value, the internal time information of the internal time measuring unit 211 is corrected. The predetermined value is appropriately set according to the elapsed time from the time when the previous timekeeping mode was successful to the present.
That is, when the internal time information is updated by the reference clock signal generated by the crystal resonator 22 and the oscillation circuit 212, an error of ± 0.5 s is generated per day. Therefore, there may be a time lag of the maximum internal time of “0.5 s × elapsed days” from the time of the previous time adjustment to the time adjustment in the current timekeeping mode. On the other hand, when noise or the like enters the satellite signal and accurate GPS time information cannot be acquired, the time difference between the internal time and the GPS time is larger than the time difference of the internal clock.
Therefore, by setting “0.5 s × elapsed days” as the predetermined value, the time difference between the internal time of the internal timekeeping unit 211 and the GPS time is due to a difference in internal time or an inappropriate satellite signal. It is possible to determine whether it is based on GPS time information. Then, when the time difference between the internal time and the GPS time is within a predetermined value, the capture operation control unit 216 and the decoding process control unit 217 determine that the internal time is within the internal time measuring unit 211. Update time information.

In the positioning mode, the capture operation control unit 216 and the decode processing control unit 217 control the operation of the GPS reception unit 10 and acquire it from the flash memory 135 based on the GPS time information, the UTC parameter, and the position information. Based on the time difference data, the internal time information is corrected and stored in the internal timekeeping unit 211.
Then, when the internal time information is corrected, the control unit 21 corrects the instruction of the pointer 3 via the drive circuit 213. In addition, time, position information, and the like are appropriately displayed on the display 4 via the drive circuit 214.

[Configuration of power supply device]
The power supply circuit 30 includes a regulator 31, a secondary battery 32, a battery voltage detection circuit 33, a charge control circuit 34, a solar cell 35, and a power generation amount detection circuit 36 that constitutes a power generation amount detection means.

The secondary battery 32 supplies driving power to the GPS receiver 10 and the time display device 20 through the regulator 31.
The battery voltage detection circuit 33 is operated by a control signal from the control unit 21 and monitors the voltage of the secondary battery 32.

  The charging control circuit 34 is disposed between the solar cell 35 and the secondary battery 32, and controls charging of the secondary battery 32 by the current supplied from the solar cell 35.

  As described above, the power generation amount detection circuit 36 detects the power generation amount generated by the solar cell 35 and outputs a power generation detection signal corresponding to the power generation amount to the control unit 21 of the time display device 20.

[Receive processing]
Hereinafter, the procedure of the reception process in the GPS wristwatch 1 of the first embodiment will be described with reference to the flowchart of FIG.
The GPS wristwatch 1 first determines whether or not setting information for setting either the timekeeping mode or the positioning mode is input by the user's operation of the button 6 or the like, that is, whether or not the manual mode is set. (Step S1).

In step S1, when the control unit 21 of the time display device 20 recognizes the input of the setting information and determines that it is in the manual mode, it further determines whether or not the setting information is information for switching to the positioning mode. Judgment is made (step S2).
In step S2, when the control unit 21 determines that the setting information for switching to the positioning mode is input, that is, when it determines “Yes”, the capture operation control unit 216 of the control unit 21 and the decoding process control are determined. The unit 217 outputs a control signal to the GPS receiving unit 10 and performs a satellite signal reception process corresponding to the positioning mode (step S10).

  In step S2, the control unit 21 determines that the setting information for switching to the timekeeping mode has been input, that is, if it determines “No”, the capture operation control unit 216 of the control unit 21 and the decoding process The control unit 217 outputs a control signal to the GPS receiving unit 10 and performs satellite signal reception processing corresponding to the time measurement mode (step S20).

  On the other hand, when the control unit 21 determines that the setting information is not input in step S1, that is, when it is determined “No”, the reception mode setting unit 215 sets the reception mode to the automatic timekeeping mode (step S3). ).

  In the automatic timekeeping mode, the control unit 21 refers to the internal time information of the internal timekeeping unit 211 and determines whether or not a preset time, for example, 0:00, is counted (step S4). In step S4, when it is determined that it is on time, that is, when “Yes” is determined, the capture operation control unit 216 and the decoding process control unit 217 of the control unit 21 output a control signal to the GPS receiving unit 10. Then, the satellite signal reception process corresponding to the time measurement mode in step S20 is performed. On the other hand, when it is determined that it is not scheduled, that is, when it is determined “No”, the setting information of the user is waited for input and the process returns to step S1.

(Reception processing in positioning mode)
Next, the reception process in the positioning mode in step S10 will be described with reference to the flowchart of FIG.
In the reception process in the positioning mode in step S10, the threshold setting unit 15 of the GPS receiving unit 10 reads the upper limit value Th1 recorded in advance in the flash memory 135 and sets it as the initial value of the signal reception threshold (step S11).

Thereafter, the baseband unit 13 searches for a satellite signal transmitted from the GPS satellite 5 and executes a satellite capturing operation (search operation) for capturing the satellite signal (step S12).
Specifically, the baseband unit 13 generates a local code having the same pattern as the C / A code of the satellite number SV while sequentially changing the satellite number SV from 1 to 30. Next, the baseband unit 13 calculates a correlation value between the C / A code and the local code included in the baseband signal. If the C / A code and the local code included in the baseband signal are the same code, the correlation value has a peak at a predetermined timing, but if the code is different, the correlation value does not have a peak and is always almost zero.
The baseband unit 13 adjusts the local code generation timing so that the correlation value between the C / A code and the local code included in the baseband signal is maximized. In addition, when the correlation value is equal to or greater than a predetermined threshold value, the baseband unit 13 detects the signal strength (SNR) of the satellite signal and determines whether the detected signal strength is equal to or greater than the signal reception threshold. The baseband unit 13 determines that the GPS satellite 5 having the satellite number SV has been captured when the correlation value is equal to or greater than a predetermined threshold value and the signal strength is equal to or greater than the signal reception threshold.
At this time, the threshold variable timing setting unit 16 of the threshold setting unit 15 starts counting the number of correlations by the baseband unit 13. That is, the threshold variable timing setting unit 16 counts the number of correlations as 1 when the correlations of the satellite numbers SV from 1 to 30 are performed once.

Then, the baseband unit 13 determines whether or not a satellite signal has been captured (step S13). That is, the baseband unit 13 performs satellite acquisition processing until the number of correlations counted by the threshold variable timing setting unit 16 reaches a predetermined number (3 in the present embodiment), and at least three within the predetermined number of correlations. It is determined whether or not the above satellite signals have been captured.
When it is determined in step S13 that three or more satellite signals have not been acquired, that is, when it is determined “No”, the threshold setting unit 15 sets a lower limit value in which the signal reception threshold is set in advance. It is determined whether or not it is Th2 (step S14).
If it is determined in step S14 that the signal reception threshold is not the lower limit value Th2, the threshold setting unit 15 performs a threshold reduction process for reducing the currently set signal reception threshold by a predetermined value set in advance. (Step S15), the process of Step S12 is performed again.

  On the other hand, if it is determined in step S14 that the signal reception threshold is the lower limit value, then if at least three satellite signals cannot be captured within a predetermined number of correlations (for example, 3 times), the GPS reception unit 10 The satellite signal reception operation is terminated. At this time, for example, the time display device 20 displays information indicating that the reception has failed on the display 4, and displays the internal time counted by the internal timekeeping unit 211 with the hands 3 (step S16).

If it is determined in step S13 that the satellite signal has been captured, the baseband unit 13 performs a decoding process on the captured satellite signal (step S17).
Then, the time display device 20 displays information indicating that the reception is successful on the display 4, and based on the time difference data acquired from the flash memory 135 based on the GPS time information and the UTC parameter and the position information, The internal timekeeping unit 211 is updated by correcting the time information.
Then, when the internal time information is updated, the control unit 21 corrects the instruction of the pointer 3 via the drive circuit 213. In addition, time, position information, and the like are appropriately displayed on the display 4 via the drive circuit 214 (step S18). Accordingly, the time display device 20 constitutes the display means of the present invention.

(Time mode reception processing)
Next, the reception process in the timekeeping mode in step S20 will be described with reference to the flowchart of FIG.
In the reception process in the timekeeping mode in step S20, the threshold setting unit 15 of the GPS receiving unit 10 reads the lower limit value Th2 recorded in advance in the flash memory 135 and fixes it as the signal reception threshold (step S21).

Thereafter, the baseband unit 13 searches for a satellite signal transmitted from the GPS satellite 5 and executes a satellite capturing operation for capturing the satellite signal detected by the search (step S22).
Specifically, as in the reception process in the positioning mode, the baseband unit 13 generates a local code having the same pattern as the C / A code of the satellite number SV while sequentially changing the satellite number SV from 1 to 30. Then, the correlation value between the C / A code and the local code included in the baseband signal is calculated.
Then, the baseband unit 13 adjusts the local code generation timing so that the correlation value between the C / A code and the local code included in the baseband signal is maximized. In addition, when the correlation value is equal to or greater than a predetermined threshold value, the baseband unit 13 detects the signal strength (SNR) of the satellite signal and determines whether the detected signal strength is equal to or greater than the signal reception threshold. The baseband unit 13 determines that the GPS satellite 5 having the satellite number SV has been captured when the correlation value is equal to or greater than a predetermined threshold value and the signal strength is equal to or greater than the signal reception threshold.

  Thereafter, the baseband unit 13 determines whether or not a desired satellite signal has been captured (step S23). Specifically, in step S23, the baseband unit 13 determines whether two satellite signals are captured or a satellite signal having a predetermined signal strength is captured within the predetermined number of correlations. Here, the satellite signal having the predetermined signal strength is, for example, an intermediate value Th3 between the upper limit value Th1 and the lower limit value Th2. In step S23, it is determined whether or not a satellite signal having a signal strength equal to or higher than the intermediate value Th3 has been captured. to decide.

  In step S23, if two satellite signals cannot be acquired and a satellite signal having a predetermined signal strength or higher cannot be acquired, it is determined whether or not a timeout has occurred (step S24). That is, the baseband unit 13 determines whether or not the number of correlations counted by the threshold variable timing setting unit 16 has reached a predetermined number (for example, 3 times). If it is determined in step S24 that a timeout has occurred, the satellite signal reception operation by the GPS receiver 10 is terminated. At this time, similarly to step S16 in the positioning mode, the time display device 20 displays, for example, information indicating that reception has failed on the display 4, and displays the internal time counted by the internal time measuring unit 211 with the pointer 3. (Step S25). If it is determined in step S24 that the timeout has not occurred, the baseband unit 13 continues the process of step S22, that is, the satellite capturing operation.

On the other hand, when two satellite signals are acquired in step S23, or when a satellite signal having a predetermined signal strength or higher is acquired, the baseband unit 13 further detects the solar cell 35 detected by the power generation amount detection circuit 36. It is determined whether or not the fluctuation value of the power generation amount is greater than or equal to a predetermined amplitude (step S26).
In step S26, if the fluctuation value (amplitude) of the power generation amount is smaller than the predetermined value, it is determined that the user wearing the GPS wristwatch 1 is not walking but is stationary at a certain position. In such a case, since the change in the signal strength of the captured satellite signal is small and the satellite signal can be stably received, the satellite signal capturing operation is stopped (step S27). Further, the captured satellite signal starts to be decoded simultaneously with the capture (step S28).

  On the other hand, if the fluctuation value of the power generation amount is greater than or equal to the predetermined value in step S26, it is determined that the user wearing the GPS wristwatch 1 is walking. In such a case, even if the satellite signal can be captured, it may be impossible to receive the satellite signal during decoding of the satellite signal due to a change in the reception environment. Therefore, the baseband unit 13 performs the satellite signal decoding process in step S28 in a state where the satellite capturing operation is continued.

As described above, it is determined whether or not a desired satellite signal has been acquired by the processing of step S23, and the acquisition operation is stopped by the processing of steps S26 to S27, whereby the reliability of the GPS time information to be acquired is obtained. It is possible to further increase the power consumption and suppress the power consumption.
That is, in the reception process in the timekeeping mode, since the signal reception threshold is set to the lower limit value Th2, only the satellite signal having a low signal strength near the lower limit value may be received. In such a case, for example, if the signal strength drops slightly due to a change in the reception environment, GPS time information may not be acquired from the captured satellite signal, and GPS time information is acquired using only one satellite signal with weak signal strength. Then, incorrect information may be acquired or reception time may become long.
On the other hand, by capturing two satellite signals, it is possible to acquire GPS time information from the other satellite signal even if the signal strength of one satellite signal is low and GPS time information cannot be acquired. It becomes possible. In addition, even when two or more satellite signals cannot be acquired, if a satellite signal with a signal strength exceeding a predetermined value can be captured, highly reliable GPS time information is acquired based on the satellite signal. Is possible. Therefore, a satellite signal with high reliability can be received by stopping the satellite capturing operation at a timing when two satellite signals are captured or when a satellite signal having a predetermined signal strength or higher is captured. In addition, if the satellite capture operation is continued until the satellite signal decoding process is completed, power consumption may increase. However, when the satellite signal satisfying the above-described step S23 is captured, the capture operation is stopped. By doing so, power consumption can be suppressed.

In the decoding process of step S28, the baseband unit 13 acquires the GPS time by executing the decoding process of the acquired satellite signal at the same time as the desired satellite signal is acquired.
Thereafter, the capture operation control unit 216 and the decoding process control unit 217 of the time display device 20 calculate a time difference between the GPS time acquired in step S28 and the internal time counted and stored by the internal time measuring unit 211, It is determined whether or not the time difference is within a predetermined value (step S29).
In step S29, when it is determined that the time difference between the GPS time and the internal time is within a predetermined value, that is, when “Yes” is determined, the capture operation control unit 216 and the decoding process control unit 217 The internal time of the time measuring unit 211 is corrected to the GPS time. Thereafter, the time display device 20 displays information indicating that the reception has been successful, and corrects the indication of the hands 3 via the drive circuit 213 based on the corrected internal time (step S30).

  If it is determined in step S29 that the time difference between the GPS time and the internal time is greater than or equal to a predetermined value, that is, if “No” is determined, the processing in step S25 is performed and the reception operation has failed. Is displayed on the display 4 and the pointer 3 is driven based on the internal time of the internal time measuring unit 211.

  In the above example, in the case where only one satellite signal with a predetermined signal strength less than the predetermined signal strength is captured in step S23, the satellite signal decoding process is not performed. However, the present invention is not limited to this. . That is, even if only one satellite signal having a weak signal strength is acquired in step S23, the decoding process in step S28 may be performed. In this case, the satellite capturing operation is not stopped, and at the same time as the satellite capturing operation. Decode the captured satellite signal. When the GPS time information is acquired using only one satellite signal having a weak signal strength as described above, the time until the satellite signal is completely decoded may be longer. However, the acquired GPS can be obtained by performing the process of step S29. Since the internal time is corrected after determining the reliability of the time information, a certain clock reliability can be maintained.

  Next, the satellite signal reception time in the timekeeping mode in this embodiment will be described with reference to FIGS. In FIG. 7, the dotted line portion of satellite A means that the satellite signal is being searched and has not yet been captured. The solid line portion means that the satellite is captured and the satellite signal is being decoded. Furthermore, in FIG. 7, the upper side in the figure shows the signal reception state in the comparative example, and the lower side in the figure shows the signal reception state in the present embodiment. FIG. 8 is a diagram showing the relationship between the signal strength and the time required to acquire GPS time information. The broken line indicates a comparative example, and the solid line indicates the present embodiment.

Here, in the time measurement mode, as in the positioning mode, an example in which the upper limit value Th1 is set as the initial value of the signal reception threshold and the process of decreasing the number according to the number of correlations is used as a comparative example of the present embodiment.
As shown in FIG. 7, in the timekeeping mode, as shown in the comparative example, when the initial value of the signal reception threshold is set to Th1, which satellite signal is used until the signal reception threshold is reduced. Cannot be captured, and the satellite signal of the GPS satellite 5 (satellite A) positioned at a low elevation angle can be captured only after the signal reception threshold is reduced.
On the other hand, in the GPS wristwatch 1 of the present embodiment, the signal reception threshold is fixed to the lower limit value in the time measurement mode. Accordingly, since a satellite signal having a signal strength equal to or higher than the lower limit value can be received, the satellite signal of the satellite A can be captured early from the start of reception. As a result, the satellite signal of the satellite D can be captured earlier than the comparative example by the time T1 in the figure, and the time required for information acquisition can be advanced by T2.

  Also, as shown in FIG. 8, when a satellite signal with high signal strength can be captured, there is no significant difference in the reception time until acquisition of GPS time information in the comparative example and this embodiment. On the other hand, when only a satellite signal with a low signal intensity can be captured, the GPS wristwatch 1 of this embodiment can complete the reception of the satellite signal earlier than the comparative example, and as a result, the power required for the reception process Can be reduced.

[Effects of First Embodiment]
As described above, in the GPS wristwatch 1 of the first embodiment, the reception mode setting unit 215 uses the positioning mode for acquiring GPS time information (Z count data) and orbit information, and GPS time information (Z count data). The threshold setting unit 15 sets a signal reception threshold at the time of satellite signal reception in this mode. That is, the threshold setting unit 15 sets a positioning threshold (upper limit value Th1) as an initial value of the signal reception threshold in the positioning mode, and gradually decreases the signal reception threshold according to the number of correlations. On the other hand, in the timekeeping mode, the signal reception threshold is set to a timekeeping fixed threshold (lower limit value Th2) smaller than the positioning threshold. Then, the baseband unit 13 captures a satellite signal having a signal strength that is equal to or higher than the set signal reception threshold value, and performs a decoding process.
For this reason, in the positioning mode in which it is necessary to acquire accurate position information with high accuracy, it is possible to preferentially acquire satellite signals with high signal strength based on a high signal reception threshold, and to improve the accuracy of positioning processing. be able to. Also, in the timekeeping mode, by using a fixed timekeeping threshold value that is smaller than the positioning threshold value, a satellite signal with a low signal strength can be obtained from the start of reception even in an environment where a satellite signal with a high signal strength is not input. Can be captured and decoded. Therefore, the time from the start of reception to the acquisition of the satellite signal can be shortened compared with the case where the reception processing in the time measurement mode is performed with the same signal reception threshold as in the positioning mode, and thus the reception until the GPS time information acquisition is completed. Time can be shortened. Therefore, power consumption required for reception can be suppressed, and inconveniences such as system down due to a decrease in power supply voltage can be prevented.

In addition, the baseband unit 13 performs a satellite capture operation, that is, a satellite signal that can be captured when two satellite signals are captured in a time measurement mode or when a satellite signal with a predetermined signal strength or higher is captured. Stop the search operation to search.
For this reason, since the satellite capturing operation is stopped when the two satellite signals are captured, the power consumption can be suppressed as compared with the case where the satellite capturing operation is continued. In addition, when only one satellite signal with low signal strength is captured and decoding processing is performed, when the signal strength decreases, decoding processing becomes difficult and processing takes time. Information may not be collected. On the other hand, when two satellite signals are captured and each of them is decoded, GPS time information can be obtained from the other satellite signal even if the signal strength of one satellite signal drops. Processing can be carried out smoothly. In addition, since it is only necessary to acquire GPS time information of a satellite signal that has been previously decoded among the two satellite signals, it is possible to prevent a long reception time. Furthermore, generally, when two satellite signals are received, the decoding process is completed first for the one with the higher signal strength. Therefore, GPS time information can be acquired from a satellite signal having a high signal strength, and the reliability of the GPS time information is improved.
Further, even when the two satellite signals cannot be acquired, the baseband unit 13 stops the satellite capturing operation by capturing a satellite signal having a predetermined signal strength or higher. In such a satellite signal, there are few noise components, the time required for the decoding process is shortened, and the reliability of the GPS time information to be acquired is increased. If a satellite signal with high signal strength and high reliability is captured, the satellite capture operation is stopped when the satellite signal is captured, so that the satellite capture operation is not continued. Can reduce power consumption.

At this time, the baseband unit 13 refers to the power generation amount of the solar cell 35 detected by the power generation amount detection circuit 36. If the fluctuation value of the power generation amount is equal to or greater than a predetermined value, the baseband unit 13 continues the satellite capturing operation. When the fluctuation value of the power generation amount is smaller than the predetermined value, the satellite capturing operation is stopped.
If the fluctuation value of the power generation amount of the solar cell 35 is greater than or equal to a predetermined value, it can be determined that the user is walking. In such a case, if the user enters the shadow of the building, the GPS wristwatch 1 Reception environment may deteriorate. Here, as described above, when the decoding process is performed by using only two satellite signals, it is considered that the signal strengths of these two satellite signals both fall, and the decoding process becomes difficult. On the other hand, in this embodiment, when the fluctuation value of the power generation amount is equal to or greater than the predetermined value and it is determined that the user is walking, the satellite capture operation is continued, and reception is performed as described above. Even if the environment deteriorates, other securable satellite signals can be searched. When a securable satellite signal is detected, the satellite signal is captured and a decoding process is performed. As a result, the reception process in the timekeeping mode can be further stabilized, and an increase in reception time due to a change in the reception environment can be prevented.

Then, the capture operation control unit 216 and the decoding process control unit 217 of the time display device 20 calculate the time difference between the GPS time of the GPS time information acquired from the satellite signal and the internal time counted by the internal time measuring unit 211 and stored. When the time difference is within a predetermined value, the internal time is corrected to the GPS time.
The internal time counted by the internal timekeeping unit is updated by a reference clock signal generated by the crystal resonator 22 and the oscillation circuit 212, and the amount of time deviation per day is about 0.5 seconds. . Therefore, when the time difference between the GPS time and the internal time is large, noise or the like is mixed in the acquired satellite signal, and accurate GPS time information cannot be acquired. In this case, the capture operation control unit 216 and the decoding process control unit 217 do not correct the internal time information. Thereby, it is possible to prevent the wrong time from being displayed due to the wrong GPS time information, and to improve the reliability of the timepiece.

Further, the threshold value setting unit 15 sets the initial value of the signal reception threshold value to the upper limit value Th1 in the positioning mode, and fixes the signal reception threshold value to the lower limit value Th2 in the time measurement mode.
Therefore, in the positioning mode, at the start of reception, only satellite signals having a signal strength exceeding the upper limit value Th1 are received, and orbit information and GPS time information can be acquired based on good quality satellite signals with less noise components. . In the timekeeping mode, by setting the signal reception threshold to the lower limit value Th2, it is possible to capture all satellite signals from which GPS time information can be acquired, and GPS time from any of these satellite signals. Since information is acquired, a quicker reception process can be performed.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 9 is a diagram illustrating a signal reception threshold set in each mode of the GPS wristwatch according to the second embodiment.

  In the GPS wristwatch 1 of the first embodiment, when the button 6 or the like is operated by the user and is manually switched to the timekeeping mode (manual timekeeping mode), the timepiece is automatically measured. In both cases of switching to the hour mode, the signal reception threshold is set to the lower limit value Th2. However, in the GPS wristwatch 1 of the second embodiment, different signal reception thresholds are used in the manual timing mode and the automatic timing mode. Set.

In FIG. 9, an alternate long and short dash line B1 indicates a signal reception threshold in the positioning mode, a broken line B2 indicates a signal reception threshold in the timekeeping mode, and a solid line B3 indicates a signal reception threshold in the automatic timekeeping mode.
In the GPS wristwatch 1 of the second embodiment, as shown in FIG. 9, the threshold setting unit 15 sets the signal reception threshold when the automatic timekeeping mode is set by the reception mode setting unit 215. As in the first embodiment, the lower limit value Th2 is set. On the other hand, when the manual timekeeping mode is set by the reception mode setting unit 215, the threshold setting unit 15 sets a value smaller than the positioning threshold (upper limit value Th1) and larger than the lower limit value Th2.
This value may be a value that can be appropriately set by a user's setting input, or a preset value may be used.
When using a preset value, it is preferable to set an intermediate value Th3 between the upper limit value Th1 and the lower limit value Th2. That is, when the signal reception threshold value in the manual timekeeping mode is fixed at a value between the intermediate value Th3 and the upper limit value Th1, a satellite signal having a high signal strength can be acquired. However, depending on the reception environment, the satellite signal is received. There are cases where it is impossible On the other hand, when the signal reception threshold is set between the lower limit value Th2 and the intermediate value Th3, more satellite signals that can receive GPS time information can be captured. May take. In particular, in the manual timekeeping mode, the user often intends to perform timekeeping processing. In such a case, it is preferable to complete the processing more quickly. Therefore, in the second embodiment, the signal reception threshold is set to the intermediate value Th3 in order to shorten the time required for decoding processing in addition to the time required for satellite acquisition.

[Effects of Second Embodiment]
In the GPS wristwatch 1 of the second embodiment, the threshold setting unit 15 sets and fixes the lower limit value Th2 as the signal reception threshold value in the automatic timekeeping mode, and the upper limit value Th1 as the signal reception threshold value in the manual timekeeping mode. And the intermediate value Th3 of the lower limit value Th2 is set and fixed.
For this reason, in the manual timing mode, a satellite signal having a signal intensity equal to or higher than the intermediate value Th3 is captured. Such a satellite signal has fewer noise components and a shorter decoding time than a satellite signal having a signal strength near the lower limit Th2. Therefore, the reception process can be shortened when the time measurement process is manually performed. The manual timekeeping mode is intended for the user to perform timekeeping processing, and the GPS wristwatch 1 is often intentionally maintained in a state in which the reception environment is good. Therefore, as described above, even if the signal reception threshold is set to the intermediate value Th3 larger than the lower limit value Th2, the signal strength of the input satellite signal becomes relatively large. For this reason, even when the signal reception threshold is not set to the lower limit Th2, the satellite signal can be captured from the beginning of reception start, and the inconvenience that the time from the start of reception to the satellite capture can be avoided. .

  On the other hand, in the automatic time measurement mode, the time measurement process is performed at 0:00, which is a fixed time. When the time measurement process is performed at such a fixed time, the GPS wristwatch 1 may be in a room with a poor reception environment, and the signal strength of the input satellite signal becomes smaller. Therefore, by setting and fixing the lower limit value Th3 as the signal reception threshold value, a satellite signal having a small signal strength can be captured earlier, and the reception process can be completed early.

[Third Embodiment]
Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 10 is a diagram illustrating a signal reception threshold set in each mode of the GPS wristwatch according to the third embodiment.
In FIG. 10, an alternate long and short dash line B1 indicates a signal reception threshold in the positioning mode, a broken line B2 indicates a signal reception threshold in the normal timing mode, and a solid line B4 indicates a signal reception threshold in the automatic timing mode.

  In the GPS wristwatch 1 of the first and second embodiments, the reception mode setting unit 215 has a positioning mode for acquiring Z count data, week number data, and orbit information, a time measuring mode for acquiring only Z count data, and automatic. The timekeeping mode is switched. On the other hand, in the GPS wristwatch 1 of the third embodiment, in the timekeeping mode, the normal timekeeping mode in which only the Z count data is acquired, and the week number that is date information in addition to the Z count data. Set either one of the detailed timekeeping modes that also acquire data.

  Specifically, in the GPS wristwatch 1 according to the third embodiment, when setting information for switching to the normal timekeeping mode is input by the user operating the button 6 or the like, the reception mode setting unit 215 receives When setting information for switching the mode to the normal timekeeping mode and switching to the detailed timekeeping mode is input, the reception mode setting unit 215 switches the reception mode to the detailed timekeeping mode.

  Then, as shown in FIG. 10, the threshold setting unit 15 sets and fixes the intermediate value Th3 as the signal reception threshold when switched to the normal timekeeping mode. In the present embodiment, the intermediate value Th3 is set as the signal reception threshold value in the normal timekeeping mode, but the lower limit value Th2 may be set as in the first embodiment. The description of the normal time measurement mode is the same as the time measurement mode of the first embodiment and the second embodiment, and the positioning mode is the same as that of the first and second embodiments. Is omitted.

On the other hand, when switched to the detailed time measurement mode, the threshold setting unit 15 sets the threshold value Th4 for detailed time measurement as a signal reception threshold value that is larger than the intermediate value Th3 and smaller than the upper limit value Th1.
This is because in the detailed time measurement mode, week number data is acquired from the satellite signal in addition to the Z count data, and acquiring a more reliable satellite signal leads to a reduction in reception time. It is. That is, as described above, since the Z count data is transmitted every 6 seconds, even if the decoding process of the Z count data fails, if the Z count data of the next subframe transmitted after 6 seconds is obtained. Good. On the other hand, the week number data is 10-bit data and is not easily affected by noise because the data size is small. However, as shown in FIG. 2, data included in only subframe 1 and transmitted every 30 seconds. It is. Therefore, when acquisition of week number data in subframe 1 fails, it is necessary to wait for 30 seconds until acquisition of week number data in subframe 1 to be transmitted next. For this reason, when acquiring week number data, it is preferable to accurately acquire accurate data using a satellite signal having a high signal strength. Accordingly, in the detailed time measurement mode, as described above, it is preferable to set the detailed time measurement threshold Th4, which is a second time measurement fixed threshold larger than the time measurement fixed threshold used in the normal time measurement mode.

  In the detailed time measurement mode, the capture operation control unit 216 and the decoding process control unit 217 calculate the date of the beginning of the week based on the acquired week number data, and the calculated date of the start of the week. The current date and time are obtained by adding the Z count data to.

  In the third embodiment, the reception mode setting unit 215 is configured to set the detailed timekeeping mode by a user setting input. However, the present invention is not limited to this. For example, the automatic timekeeping mode that is initially performed at the beginning of the week may be switched to the detailed timekeeping mode. That is, since the week number is data that is updated in units of one week, when the week number is acquired once at the beginning of the week, the week is not updated thereafter. Therefore, if the week number is acquired once at the beginning of the week, the date and time can be corrected by acquiring only the Z count data.

[Effects of Third Embodiment]
In the GPS wristwatch 1 of the third embodiment, in the timekeeping mode, the reception mode setting unit 215 further acquires detailed date and time information (week number data) in addition to time information (Z count data). A mode and a normal time measurement mode in which only time information (Z count data) is acquired are switched and set. Then, the threshold value setting unit 15 sets the signal reception threshold value to the intermediate value Th3 in the normal time measurement mode, and is a second time measurement fixed threshold value that is larger than the intermediate value Th3 and smaller than the upper limit value Th1 in the detailed time measurement mode. It is set to a certain threshold value Th4 for time measurement.
For this reason, in the detailed time measurement mode, the week number data transmitted at 30-second intervals can be reliably acquired, and the inconvenience that the reception process becomes long due to the failure to acquire the week number data can be avoided.

[Fourth Embodiment]
Next, a fourth embodiment of the present invention will be described.
In the GPS wristwatch 1 of the first embodiment described above, the capture operation control unit 216 and the decode processing control unit 217 have a time difference between the GPS time of the acquired GPS time information and the internal time stored in the internal timekeeping unit 211. When it was within the predetermined value, the internal time was corrected to GPS time. On the other hand, in the fourth embodiment, the GPS time information of the two captured satellite signals is decoded, and when the GPS times of these GPS time information match, the time difference between the internal time and the GPS time is referred to. If the time difference is within a predetermined value, the internal time is corrected.

  Here, as described above, in the timekeeping mode, in order to avoid the decoding process using only the satellite signal having a low signal intensity, the two satellite signals are captured and the decoding process is performed. In the first embodiment, the internal time is corrected based on the decoded GPS time information at the time when either one of the two satellite signals is decoded. The reception operation is continued until the decoding processing of one satellite signal is completed. Then, when the decoding processing of these two satellite signals is completed and the two GPS time information is acquired, the capturing operation control unit 216 and the decoding processing control unit 217 determine whether or not these GPS time information matches. Judging. Here, when it is determined that the two GPS time information matches, as described above, the time difference between the GPS time of the GPS time information and the internal time recorded in the internal timekeeping unit 211 is calculated, and the time difference is a predetermined value. If it is within, correct the internal time.

  On the other hand, if the two pieces of GPS time information do not match, it is determined that at least one of the obtained two pieces of GPS time information is incorrect information, and the reception operation is stopped. In this case, the process of step S25 of the first embodiment is performed, for example, information indicating that reception has failed is displayed on the display 4, and the internal time counted by the internal time measuring unit 211 is displayed on the hands 3. Process.

  Note that if the acquisition operation control unit 216 and the decode processing control unit 217 determine that the two GPS time informations do not match, the acquisition operation control unit 216 may continue the satellite acquisition operation and further perform processing to acquire other satellite signals. . In this case, the newly acquired satellite signal may be decoded to acquire GPS time information, and it may be determined whether there is matching GPS time information as compared with the previously acquired GPS time information. Here, if there is matching GPS time information, the time difference between the GPS time of the matched GPS time information and the internal time is calculated, and if this time difference is within a predetermined value, the internal time is converted to the GPS time. Implement the process to correct.

[Effects of Fourth Embodiment]
In the GPS wristwatch 1 of the fourth embodiment, in the timekeeping mode, the capture operation control unit 216 and the decode processing control unit 217 decode two satellite signals to acquire GPS time information, and acquire these GPS times. When the information matches, the time difference between the GPS time of the GPS time information and the internal time of the internal timekeeping unit is calculated. If the time difference is within a predetermined value, the internal time is corrected to the GPS time.
For this reason, compared with the GPS wristwatch 1 of the first embodiment, the time until the reception operation is completed is longer, but more reliable information can be acquired as GPS time information acquired from the satellite signal. It is possible to reliably prevent display of incorrect information.

[Modification]
In addition, this invention is not limited to said each embodiment, A various deformation | transformation implementation is possible within the range of the summary of this invention.
For example, in the positioning mode, every time the number of correlations reaches a predetermined number (for example, 3 times), the signal reception threshold is reduced. The threshold setting unit 15 gradually delays the timing for reducing the signal reception threshold. Processing may be performed. For example, the threshold setting unit 15 performs the first threshold reduction process when the number of correlations becomes 3 from the start of reception, and then performs the second threshold reduction process after five more correlations are performed. After that, when the correlation is further performed seven times, a third threshold reduction process may be performed.
Further, the threshold setting unit 15 performs processing for decreasing the signal reception threshold according to the number of correlations in the positioning mode. For example, the threshold setting unit 15 refers to the elapsed time from the start of reception by an internal timer and is necessary for the predetermined number of correlations. You may implement the process which decreases a signal reception threshold every time progress.

  In the first embodiment, the threshold value setting unit 15 sets the lower limit value Th2 as the signal reception threshold value in the time measurement mode. However, the threshold value setting unit 15 is not limited to this and may be set to a value smaller than the positioning threshold value. However, if a value close to the positioning threshold value is set, satellite reception that cannot be captured increases, and as a result, the reception time becomes longer. Therefore, it is preferable to set it to an intermediate value Th3 or less between the upper limit Th1 and the lower limit Th2. By setting such a signal reception threshold value, at least a satellite signal having a signal intensity capable of acquiring GPS time information can be quickly captured, and the reception time can be shortened.

  In the second embodiment, the threshold setting unit 15 sets the intermediate value Th3 as the signal reception threshold in the manual timekeeping mode. In the third embodiment, the threshold value setting unit 15 sets the intermediate value Th3 as the signal reception threshold in the normal timekeeping mode. However, it may be set to another value that is smaller than the upper limit value Th1 and larger than the lower limit value L2, and is set to a value that is larger than the lower limit value Th2 and smaller than the intermediate value Th3. It can be shortened more.

  Furthermore, in the first to third embodiments, the capture operation control unit 216 and the decoding processing control unit 217 receive two satellite signals, and the GPS signal of one of the satellite signals for which decoding processing has been completed out of these satellite signals. Although the time correction is performed when the time difference between the time information and the internal time is within a predetermined value, the present invention is not limited to this. For example, as in the fourth embodiment, when the GPS time information of two satellite signals matches, a process of correcting the time may be performed. In addition, when the signal strength is sufficiently large, the internal time may be corrected without calculating the time difference between the GPS time of the acquired GPS time information and the internal time.

  In addition, it is determined whether or not the GPS time information of two satellite signals match. However, a process is performed to determine whether or not the GPS time information of two or more satellite signals, for example, three satellite signals match. Also good. In this case, the inconvenience of acquiring incorrect GPS time information can be avoided more reliably.

  Furthermore, in each of the above embodiments, the stop timing of the satellite capturing operation is a case where two or more satellite signals are captured, or a satellite signal having a predetermined signal strength or more is captured, but is not limited thereto. . For example, in order to acquire the GPS time information, it is only necessary to acquire the time from one satellite signal, and therefore, the satellite capturing operation may be stopped at the timing when one satellite signal is captured. In addition, although the timing at which two satellite signals are captured has been described, for example, when a predetermined number of three or more satellite signals are captured, the capturing operation may be stopped. Alternatively, the capturing operation may be stopped when a predetermined number of two or more is captured.

  In addition, the capture operation control unit 216 and the decoding process control unit 217 determine whether or not the user is walking based on the fluctuation value of the power generation amount of the solar cell 35. It may be determined whether or not the user is walking, and furthermore, in a power generation type electronic timepiece that generates power by rotating a rotating weight, the power generation amount is detected. Thus, it may be determined whether or not the user is walking.

  Moreover, although the above-mentioned embodiment demonstrated the GPS satellite 5 as an example of a position information satellite, as a position information satellite of this invention, not only the GPS satellite 5, but Galileo (EU), GLONASS (Russia), Hokuto ( Other global navigation satellite systems (GNSS) such as China) or position information satellites that transmit satellite signals including time information such as geostationary satellites such as SBAS and quasi-zenith satellites may be used.

  The electronic timepiece of the present invention is not limited to a combination timepiece having hands and a display, but may be applied to an analog timepiece having only hands and a digital timepiece having only a display. Furthermore, the present invention is not limited to a wristwatch, and may be applied to various watches such as a pocket watch, and electronic devices having a watch function such as a mobile phone, a digital camera, and various portable information terminals.

  DESCRIPTION OF SYMBOLS 1 ... GPS wristwatch which is an electronic timepiece, 5, 5a, 5b, 5c, 5d ... GPS satellite which is a position information satellite, 6 ... Button which constitutes input means, 13 ... Baseband which functions as receiving means and information acquiring means 15, a threshold setting unit that is a threshold setting unit, 20 a time display device that constitutes a display unit, 35 a solar cell, 36 a power generation amount detection circuit that is a power generation amount detection unit, 211 an internal timing unit, 215. A reception mode setting unit that is a mode switching unit, 216... A capture operation control unit that constitutes a time correction unit, 217... A decoding process control unit that constitutes a time correction unit.

Claims (7)

Performs a search process that searches for satellite signals that can be captured from satellite signals transmitted from multiple position information satellites, and among the satellite signals captured by the search process, satellite signals whose signal strength is equal to or greater than a predetermined signal reception threshold Receiving means for receiving
Information acquisition means for acquiring predetermined information based on a satellite signal received by the reception means;
Display means for displaying the acquired information;
Switching between a time measurement mode in which the time information included in the satellite signal is acquired by the information acquisition means, and a positioning mode in which the position information included in the satellite signal is acquired by the information acquisition means and the position of the electronic timepiece is calculated. Mode switching means;
Threshold setting means for setting the signal reception threshold according to the mode switched by the mode switching means,
The threshold setting means includes
A search that is the number of times that the search processing is performed on the satellite signals of all position information satellites while setting the initial value of the signal reception threshold to a predetermined positioning threshold when switched to the positioning mode. According to the number of times, the signal reception threshold is decreased stepwise,
An electronic timepiece characterized in that, when switched to the timekeeping mode, the signal reception threshold is set to a timekeeping fixed threshold that is less than the positioning threshold and equal to or greater than a predetermined lower limit. The electronic timepiece according to claim 1,
Input means capable of inputting setting information for switching to either one of the positioning mode and the timekeeping mode,
The mode switching means is
When the setting information is input from the input means and the satellite signal is received, based on the setting information, the mode is switched to one of the time measurement mode and the positioning mode,
When receiving the satellite signal at a predetermined time, switch to the automatic timekeeping mode to acquire the time information,
The threshold setting means includes
When switched to the timekeeping mode, as the signal reception threshold, set a fixed timekeeping threshold value smaller than the positioning threshold value and larger than a lower limit value,
An electronic timepiece characterized in that, when switched to the automatic timekeeping mode, the signal reception threshold is set to the lower limit value. The electronic timepiece according to claim 1,
The mode switching means further includes a normal timekeeping mode for acquiring only the time information when the mode is switched to the timekeeping mode, and details for acquiring the date information and the time information included in the satellite signal. Switch to time mode,
The threshold setting means includes
When switched to the normal timekeeping mode, the signal reception threshold is set to the timekeeping fixed threshold,
The electronic timepiece characterized in that, when switched to the detailed timekeeping mode, the signal reception threshold is set to a second timekeeping fixed threshold that is smaller than the positioning threshold and larger than the timekeeping fixed threshold. . The electronic timepiece according to any one of claims 1 to 3,
The reception unit stops the search process when a predetermined number of satellite signals are acquired in the timekeeping mode or when a satellite signal with a predetermined signal strength or higher is acquired. . The electronic timepiece according to claim 4,
A solar cell that receives light to generate power, and a power generation amount detecting means for detecting the power generation amount in the solar cell,
In the timekeeping mode, the receiving means is configured such that when the fluctuation value of the power generation amount detected by the power generation amount detection means is equal to or greater than a predetermined value, when a predetermined number of satellite signals are captured, or greater than a predetermined signal strength The electronic timepiece is characterized in that the search process is continued until the time information is acquired by the information acquisition means even when the satellite signal is captured. The electronic timepiece according to any one of claims 1 to 5,
An internal timekeeping section that counts time,
Based on the time information acquired by the information acquisition means, and a time correction means for correcting the time counted by the internal timekeeping unit,
In the timekeeping mode, the time correction means adds the time information to the time information when a time difference between the time of the time information acquired by the information acquisition means and the time of the internal timekeeping unit is a predetermined value or less. An electronic timepiece characterized in that the time of the internal timekeeping unit is corrected based on the electronic timepiece. The electronic timepiece according to any one of claims 1 to 5,
An internal timekeeping section that counts time,
Based on the time information acquired by the information acquisition means, and a time correction means for correcting the time counted by the internal timekeeping unit,
In the timekeeping mode, the time adjustment means is configured to acquire two or more satellite signals by the receiving means, and when the signal strength of these captured satellite signals is smaller than a predetermined signal intensity, Based on the time information, when the time information acquired from the satellite signals is substantially the same, and the time difference between the time of the time information and the time of the internal timekeeping unit is a predetermined value or less. And correcting the time of the internal timekeeping section.

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