JP5076921B2 - Time measuring device and satellite signal receiving method of time measuring device - Google Patents

Description

  The present invention relates to a clock device that receives a radio wave transmitted from a positioning satellite such as a GPS satellite and obtains the current date, time, and the like, and a satellite signal reception method of the clock device.

  In a GPS (Global Positioning System) system, which is a system for positioning its own position, a GPS satellite having an orbit around the earth is used, and this GPS satellite is provided with an atomic clock. For this reason, the GPS satellite has extremely accurate time information (GPS time, satellite time information).

An electronic timepiece that corrects the time using the time information (GPS time) of the GPS satellite has been proposed (Patent Document 1).
A signal (navigation message) from a GPS satellite transmits a frame or a subframe in synchronization with the reset of the C / A code (Coarse and Acquisition Code) at the beginning of the week of GPS time. Therefore, if the navigation message can be decoded using the C / A code, the elapsed time from the beginning of the week of the GPS time can be known from only the signal from one satellite, and the time can be corrected with an accuracy of about 0.1 second. .
In other words, since the orbit of the GPS satellite is about 20000 to 27000 km, the propagation time of the radio wave is about 66.6 to 90 milliseconds, and by correcting this, UTC (Coordinated Universal Time) with an error of the order of milliseconds It is possible to synchronize with the clock, and it is possible to measure the accuracy with no problem in practical use.

Japanese Patent Laid-Open No. 10-10251

  Incidentally, the electronic timepiece of Patent Document 1 is a timepiece that is fixedly installed like a table clock or a wall clock, and the GPS satellite signal is also assumed to be received at a fixed point. Since the GPS satellite makes one round of the earth in about 12 hours, the GPS satellite that can be received at the present time can be judged and selected and captured quickly by referring to the satellite history and orbit information received last time. And a satellite signal can be received reliably.

  However, in the case of a watch such as a wristwatch, it may be received while the user is wearing it, that is, while moving, or indoors. Also, in the case of a watch that is carried, the probability that the user will receive it manually is higher than that of a watch that is used in a fixed manner. Accordingly, in a wristwatch or the like, the reception position and reception time may be different from the previous time during the reception process, and the previous reception history cannot be used effectively.

For this reason, a wristwatch that can receive signals from GPS satellites often has to perform a satellite search from a cold start state in which satellite orbit information is not retained.
Therefore, when receiving time information, it is necessary to search for GPS satellites at random. If the navigation data (NAV data) can be decoded by the GPS satellite first captured when this search process is performed, the reception time can be shortened and the power consumption can also be reduced.
However, there is a possibility that the signal from the captured GPS satellite is a weak signal, or the captured satellite is decaptured due to a change in the course of the receiving user or in the shadow of a high-rise building during reception while moving. High, it is necessary to re-search for GPS satellites each time, and the total reception time becomes longer and power consumption increases.

  The present invention provides a timing device and a satellite signal receiving method for the timing device that can receive satellite signals in a short time, reduce power consumption, reduce the influence of the reception environment, and improve the probability of successful reception. With the goal.

  The timing device of the present invention captures a position information satellite, receives a satellite signal transmitted from the captured position information satellite, and generates time information based on the satellite signal received by the reception section. A time measuring device comprising a time information generating unit, a time display unit for displaying time information, and a reception control unit for controlling the receiving unit, wherein the reception control unit is connected to the time measuring device before receiving processing. A determination unit that determines a reception environment, and one satellite search that acquires one time information satellite based on a satellite signal transmitted from the position information satellite when performing reception processing by the reception unit. A mode, and a plurality of satellite search modes for acquiring time information based on a satellite signal transmitted from one of the plurality of acquired location information satellites. Characterized in that it comprises a search mode selection unit that selects, based on the serial determination of the determination result.

In the present invention, the reception environment is determined by the determination unit before the reception process is performed, and the one-satellite search mode and the multiple-satellite search mode are selected based on the determination result. That is, instead of dynamically selecting the search mode based on the reception result while performing reception, the search mode is selected in advance (statically) before reception.
For this reason, when the reception process is actually performed and the search mode is dynamically selected based on the reception situation, the time from the start of the reception process to the selection of the search mode after determining the reception situation However, in the present invention, since the search can be started after selecting the search mode, the satellite signal can be received in a short time after the start of the reception, and the power consumption can be reduced.

Furthermore, since the search mode is selected based on the determination result of the determination unit, the influence of the reception environment can be reduced, the probability of successful reception can be improved, the reception time can be shortened, and the power consumption can also be reduced.
In other words, if the reception environment is good, as in the case where the signal strength (reception level) is higher than a predetermined value, even if only one position information satellite is acquired by one satellite search mode, the time information is decoded and acquired. can do. That is, in the single-satellite search mode, it is only necessary to capture a single satellite and receive a satellite signal. Therefore, when the reception environment is good and the signal strength is high, time / week information can be acquired in a short time. And power consumption can be reduced. However, in the one-satellite search mode, one satellite is captured and the received signal is decoded, and when a correct signal cannot be received, another satellite is captured and the received signal is decoded. For this reason, when the single satellite search mode is selected, and when the reception environment deteriorates and the signal strength decreases, the acquisition probability of time / week information also decreases, and the satellite search processing and NAV data decoding processing are repeated. Therefore, the reception time becomes longer and the power consumption increases.
On the other hand, if the reception process is performed only in the multiple satellite search mode, the power consumption will increase compared to the single satellite search mode if the reception environment is good, but the reception environment deteriorates and the signal strength is low. However, since a plurality of satellites are simultaneously searched and the received signal is decoded, the acquisition probability of time / week information can be increased, and the reception time can be shortened compared to the single satellite search mode, thereby reducing power consumption.
Therefore, as in the present invention, if the single satellite search mode and the multiple satellite search mode are selected based on the determination result of the reception environment by the determination unit, the average reception time can be shortened and the power consumption can be reduced. Even when the reception environment is deteriorated, the probability that time / week information can be acquired can be increased, the influence of the reception environment can be reduced, and the probability of successful reception can be improved.

  In the present invention, a light amount measurement unit that measures the amount of light emitted to the timing device is provided, and the determination unit determines whether the light amount measurement unit measures a light amount that is equal to or greater than a predetermined value, and the search mode selection unit The determination unit selects the one-satellite search mode when it is determined that the light quantity of a predetermined value or more is measured, and the multi-satellite search mode is selected when it is determined that the light quantity of less than the predetermined value is measured. It is preferable to select.

If the light quantity measuring unit is provided, it can be easily determined whether or not the timing device is disposed outdoors. That is, when sunlight is irradiated on the timing device, the amount of light irradiated is larger than when indoor lighting is irradiated on the timing device. Therefore, a light quantity sensor or the like is provided in the time measuring device, the light amount irradiated to the time measuring device is measured, and a predetermined value (threshold value) for determination is determined based on whether the measured light amount is sunlight, that is, the time measuring device is disposed outdoors. Is set to a value that can be determined, it can be easily determined whether or not the timing device is disposed outdoors. Since the reception environment for receiving signals from the position information satellite is likely to be better outdoors than indoors, according to the present invention, the reception environment is good by measuring the light quantity. Whether or not there is can be easily determined before the reception process.
Here, as the light amount measurement unit, a light amount sensor that directly measures the amount of light may be used, but a solar cell that generates power by light irradiation may be used. Since the amount of power generated by the solar cell changes depending on the amount of light applied to the solar cell, the amount of light can be indirectly measured by detecting the amount of power generated by the solar cell. If the solar cell is also used as the light quantity measurement unit, the number of parts can be reduced and the cost can be reduced as compared with the case where a light quantity sensor is provided separately.
The threshold for determining the light amount may be set to 5000 lx (lux), for example. In other words, if it is outdoors during the daytime, the measured illuminance is 5000 lx or more even in rainy or cloudy weather, but if it is indoors, the measured illuminance is 1000 lx or less because illumination such as a fluorescent lamp is used. Therefore, if the threshold is set to about 5000 lx, the determination unit can determine that the timing device is disposed outdoors when the measured illuminance is equal to or greater than the threshold.

  In the present invention, a moving speed measuring unit for measuring the moving speed of the timing device is provided, wherein the determining unit determines whether the moving speed measuring unit has measured a moving speed equal to or lower than a predetermined value, and selects the search mode. The unit selects the one-satellite search mode when the determination unit determines that the moving speed equal to or less than a predetermined value is measured, and the plurality of satellites when the determination unit determines that the moving speed greater than the predetermined value is measured. It is preferable to select a search mode.

According to the present invention as described above, since the moving speed measuring unit is provided, it can be determined whether the timing device is stationary or moved. When the timing device is moved, the positional relationship with the position information satellite changes. For example, as the timing device moves, the building is positioned between the captured position information satellite and the timing device. As a result, satellite signals may not be received. Therefore, it is more likely that the reception environment is better when the timing device is stationary than when it is moving. Therefore, if the movement speed of the timing device is measured, the reception environment is better. It can be easily determined before the reception process.
For example, an acceleration sensor can be used as the moving speed measurement unit.
Further, the predetermined value (threshold value) of the moving speed determined by the determination unit may be set to a value that can determine whether or not the timing device is substantially in a stationary state, for example. For example, when determining by measuring acceleration, walking is performed if the maximum acceleration per unit time when the casing is swung in two directions in the vertical direction is equal to or greater than a threshold value of 0.98 m / s ² (0.1 G). If it is less than the threshold, it can be determined that the object is stationary. That is, the maximum acceleration of the case when walking or jogging with the timing device attached to the arm is about 4.9 to 9.8 m / s ² (0.5 to 1.0 G). Therefore, the determination unit can determine whether the timing device is in a moving state or a stationary state depending on whether the measured maximum acceleration is equal to or greater than the threshold value.

  In the present invention, a storage unit for storing orbit information of the position information satellite is provided, and the determination unit is configured to acquire a position information satellite that can be captured at the time of performing reception processing based on the orbit information stored in the storage unit. Among them, it is determined whether or not there are a predetermined number or more of position information satellites positioned at a high elevation angle that is equal to or greater than a predetermined angle, and the search mode selection unit determines whether the position information satellite positioned at the high elevation angle is a predetermined level in the determination unit. It is preferable to select the one-satellite search mode when it is determined that there are more than a certain number, and to select the multiple-satellite search mode when it is determined that the number is less than a predetermined number.

If the orbit information of each position information satellite is stored in the storage unit, it is possible to know in advance whether or not there is a position information satellite located at a high elevation angle at the time of reception.
When the satellite signal from the position information satellite is received by the time measuring device, the position information satellite positioned at a low elevation angle is likely to be blocked by a building such as a building. Therefore, the reception environment is better when a position information satellite with a high elevation angle located at the zenith with respect to the time measuring device is captured than when a position information satellite with a low elevation angle is captured.
Therefore, by detecting whether or not there are a predetermined number or more of position information satellites located at a high elevation angle based on orbit information, it is possible to easily determine whether or not the reception environment is good before the reception process.
In addition, what is necessary is just to set that it is a high elevation angle, for example, if an elevation angle is 60 degree | times or more.

  In the present invention, a reception level detection unit that detects a reception level of a satellite signal received from a position information satellite, and a storage unit that stores a reception level detected by the reception level detection unit, the determination unit includes the storage The search mode selection unit determines whether the reception level at the previous reception is equal to or higher than the predetermined value in the determination unit. It is preferable that the single-satellite search mode is selected when it is determined that the multi-satellite search mode is selected.

In the present invention, when the previous reception level is equal to or higher than a predetermined value (for example, −133 dBm), the process is performed in the one-satellite search mode.
Whether it is automatic reception or manual reception, the environment at the time of each reception is generally the same. For example, when receiving at a fixed time every day, the reception environment is often the same. Also, in the case of manual reception, the reception environment is often the same, for example, the user operates outdoors every time.
Therefore, if the previous reception level is high, there is a high possibility that the reception level is high and the reception environment is good during the next reception process. If the previous reception level is low, reception is also possible during the next reception process. It is likely that the reception level is low and the reception level is not good. Therefore, it is possible to easily determine whether or not the reception environment is good based on the previous reception level before the reception process.
Note that dBm is obtained by setting 1 mW to 0 dB, for example, −130 dBm = 1 × 10 ⁻¹³ mW.

  In the present invention, a reception time measurement unit that measures a reception time from when a satellite signal is received from a position information satellite until time information is acquired, and a storage unit that stores the reception time measured by the reception time measurement unit are provided. The determination unit determines whether or not the reception time at the previous reception stored in the storage unit is equal to or less than a predetermined time, and the search mode selection unit is configured to determine the reception time at the previous reception in the determination unit. However, it is preferable to select the one-satellite search mode when it is determined that the time is equal to or shorter than the predetermined time, and to select the multi-satellite search mode when it is determined that the time is longer than the predetermined time.

In the present invention, when the previous reception processing time is a predetermined value (for example, 3 minutes) or less, the processing is performed in the single satellite search mode, and when it is longer than the predetermined value, the processing is performed in the multiple satellite search mode. .
Whether it is automatic reception or manual reception, the environment at the time of each reception is generally the same. When the reception environment is good, the reception time is shortened, and when the reception environment is deteriorated, the reception time is lengthened. Therefore, if the previous reception time is long and it can be determined that the reception environment is not very good, it is highly possible that the reception environment is not good during the next reception processing, and the previous reception time was short and the reception environment was good. If it can be determined, there is a high possibility that the reception environment is also good during the next reception process. Therefore, it is possible to easily determine whether or not the reception environment is good based on the previous reception time before the reception process.

  In the present invention, an external operation member operable by a user is provided, and the determination unit determines whether a selection operation of one satellite search mode or multiple satellite search mode is performed on the external operation member. The search mode selection unit determines that the single satellite search mode is selected when the determination unit determines that the single satellite search mode selection operation is performed, and determines that the multiple satellite search mode selection operation is performed. In this case, it is preferable to select the multiple satellite search mode.

When performing a receiving operation, a user usually has an open sky at the current location, for example, and it is easy to receive signals from a location information satellite, or there are buildings, roofs, etc. It is possible to determine whether the environment is difficult to receive signals from the position information satellite.
Therefore, if the search mode is manually selected at the discretion of the user, there is a high possibility that the mode corresponding to the reception environment can be selected, the time / week information acquisition probability can be increased, and the reception time can be shortened. Power can be reduced.

  At this time, the search mode selection unit preferably selects the single satellite search mode when the determination unit determines that neither the single satellite search mode nor the multiple satellite search mode is selected. .

  According to such a configuration, when the user performs a reception operation, even if the search mode selection operation is forgotten, the reception process can be executed in the initial one-satellite search mode. The operability is not reduced compared to the case where no reception process is performed when there is no operation.

  In the present invention, the search mode selection unit selects the multiple satellite search mode regardless of the determination result of the determination unit when performing time reception processing for the first time after the timing device is turned on. Is preferred.

  Immediately after the power is turned on, there is a high possibility that the time of the clock is shifted, so it is necessary to reliably receive the time information. For this reason, if the multiple satellite search mode is selected when the first time is received immediately after the power is turned on, the possibility that the time information can be reliably acquired is improved, and the time of the time measuring device can be corrected correctly.

  According to the satellite signal receiving method of the timing device of the present invention, a position information satellite is captured, a reception unit that receives a satellite signal transmitted from the captured position information satellite, and a satellite signal received by the reception unit. A satellite signal reception method for a time measuring device, comprising: a time information generation unit that generates time information; a time display unit that displays time information; and a reception control unit that controls the reception unit. When determining the reception environment in the time measuring device and performing the reception process by the receiving unit, one position information satellite is captured and time information is acquired based on the satellite signal transmitted from the position information satellite. A plurality of position information satellites, and a plurality of position information satellites that acquire time information based on a satellite signal transmitted from one position information satellite among the plurality of position information satellites acquired. A search mode, characterized in that it comprises a search mode selection step of selecting, based on the determination of the determination result.

According to the present invention, the reception can be started after the search mode is selected as in the case of the time measuring device, so that satellite signals can be received in a short time after the start of reception, and the power consumption can be reduced. Further, since the reception environment is determined and the search mode is selected, the satellite signal can be received in a short time, the power consumption can be reduced, the influence of the reception environment can be reduced, and the probability of successful reception can be improved.
Therefore, similar to the timing device, the average reception time can be shortened, the power consumption can be reduced, and the probability that time / week information can be acquired even when the reception environment is deteriorated can be increased. Can be reduced and the probability of successful acceptance can be improved.

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

[First Embodiment]
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 a timing device according to the present invention. FIG. 2 is a schematic diagram showing the main hardware configuration of the GPS wristwatch 1.
As shown in FIG. 1, the GPS wristwatch 1 includes a time display unit 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.

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 and the like, and displays message information as well as position information such as latitude, longitude, and city name.
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.
The GPS satellite 5 is an example of the position information satellite in the present invention, and a plurality of GPS satellites 5 exist above the earth. Currently, about 30 GPS satellites 5 orbit.

  The GPS wristwatch 1 is provided with a crown 6 and buttons 7 and 8 which are external operation members.

[Circuit configuration of GPS wristwatch]
Next, the circuit configuration of the GPS wristwatch 1 will be described. As shown in FIG. 2, the GPS wristwatch 1 includes a time display device 45, a GPS device 40, and a time correction device 44, and has a configuration that also functions as a computer. As shown in FIG. 2, the time display device 45, the GPS device 40, and the time adjustment device 44 are partially duplicated.

Hereinafter, each configuration shown in FIG. 2 will be described.
[Configuration of GPS device]
As shown in FIG. 2, the GPS wristwatch 1 includes a GPS device 40 that receives and processes a satellite signal transmitted from a GPS satellite 5.
The GPS device 40 includes a GPS antenna 11, a filter (SAW) 31, and a receiving circuit 18. The filter (SAW) 31 is a band-pass filter and extracts a 1.5 GHz satellite signal. The GPS device 40 constitutes a receiving unit of the present invention.

The receiving circuit 18 processes the satellite signal extracted by the filter 31 and includes an RF unit (Radio Frequency) 27 and a baseband unit 30.
The RF unit 27 includes a PLL circuit 34, an IF filter 35, a VCO (Voltage Controlled Oscillator) 41, an ADC (A / D converter) 42, a mixer 46, an LNA (Low Noise Amplifier) 47, an IF amplifier 48, and the like. .

The satellite signal extracted by the filter 31 is amplified by the LNA 47, mixed with the signal of the VCO 41 by the mixer 46, and down-converted to IF (Intermediate Frequency).
The IF mixed by the mixer 46 passes through an IF amplifier 48 and an IF filter 35 and is converted into a digital signal by an ADC (A / D converter) 42.

The baseband unit 30 includes a DSP (Digital Signal Processor) 39, a CPU (Central Processing Unit) 36, an SRAM (Static Random Access Memory) 37, and an RTC (Real Time Clock) 38. The baseband unit 30 is also connected with a crystal oscillation circuit with temperature compensation circuit (TCXO) 32, a flash memory 33, and the like.
The baseband unit 30 receives a digital signal from the ADC 42 of the RF unit 27, performs a satellite signal calculation (decoding process) based on the control signal, and can acquire satellite time information and positioning information. .

The clock signal for the PLL circuit 34 is generated from a crystal oscillation circuit (TCXO) 32 with a temperature compensation circuit.
The RTC 38 generates time information on the receiver side in order to process satellite signals. The RTC 38 is incremented by the reference clock output from the TCXO 32.

[Configuration of time correction device]
The time adjustment device 44 includes the reception circuit 18, the control unit 20, and the drive circuit 43.
The control unit 20 includes a storage unit 20 </ b> A and controls driving of the GPS device 40, the hands 3, and the display 4. That is, the control unit 20 constitutes a reception control unit that sends a control signal to the reception circuit 18 and controls the reception operation of the GPS device (reception unit) 40.
The storage unit 20A stores time data (satellite time information) obtained by the baseband unit 30 of the receiving circuit 18 and positioning data.

[Configuration of time display device]
The time display device 45 includes a control unit 20, an RTC 38, a TCXO 32, a storage unit 20A, a drive circuit 43, a pointer 3, a display 4, and the like. Therefore, the time display unit 45 constitutes the time display unit of the present invention.
The drive circuit 43 includes a pointer drive circuit that drives a pointer 3 by driving a step motor (not shown), and a display drive circuit that drives the display 4.
The internal time information generated by the RTC 38 is stored as the current time information in the storage unit 20A, and the control unit 20 displays the pointer 3 and the display 4 on the basis of the time data stored in the storage unit 20A. Control the time.

In addition, the control unit 20 adds UTC offset (currently +14 seconds) to the satellite time information obtained by the baseband unit 30 to obtain Coordinated Universal Time (UTC), which is further stored in the storage unit 20A. The time difference information with respect to UTC is added to calculate the local time when the GPS wristwatch 1 is used and stored in the storage unit 20A. Therefore, the control unit 20 also functions as a time information generation unit that generates time information based on the received satellite signal.
When the time information generated based on the received satellite signal is stored in the storage unit 20A and the internal time information is updated, the control unit 20 displays the corrected time information on the display 4 through the drive circuit 43. It is supposed to be displayed.
Further, the control unit 20 calculates a difference between the current time information indicated by the hands 3 and the corrected internal time information, and steps through the drive circuit 43 so that the hands 3 move by the time difference. The motor is driven and control is performed so that the hands 3 indicate the corrected time.

The GPS wristwatch 1 having such a configuration is driven by electric power supplied from a rechargeable secondary battery 24.
That is, the charging coil 22 charges the secondary battery 24 with power through the charging control circuit 28. The secondary battery 24 supplies driving power to the time adjustment device 44 and the like via the regulator 29.
As described above, the timepiece mechanism in the present embodiment is a so-called electronic timepiece.

[Explanation of navigation message]
Here, the navigation message which is a signal (satellite signal) transmitted from the GPS satellite 5 will be described.
3 and 4 are schematic explanatory views showing GPS satellite signals.
Each GPS satellite 5 transmits a signal in units of one frame data (30 seconds) as shown in FIG. This 1-frame data has 5 subframe data (1 subframe data is 6 seconds). Each subframe data has 10 words (1 word is 0.6 seconds).

The head word of each subframe data is a TLM word in which TLM (Telemetry word) data is stored. As shown in FIG. 4, preamble data is stored in the head of the TLM word.
The word following the TLM is a HOW word in which HOW (hand over word) data is stored, and at the top of the word is the GPS time information (satellite) of TOW (Time of Week, also referred to as “Z count”). Time information) is stored.
The GPS time information displays the elapsed time from 0 o'clock every Sunday in seconds, and returns to 0 at 0 o'clock on the next Sunday. In other words, the GPS time information is information in seconds indicated every week from the beginning of the week, and the elapsed time is a number expressed in units of 1.5 seconds, and is also referred to as Z count or Z count data. The GPS wristwatch 1 is a clue to know the current time.

Further, the word data of subframe 1 shown in FIG. 3 includes a word in which satellite correction data such as week number data (WN) and satellite health status information (SVhealth) data is stored.
The week number data is information representing a week including the current GPS time information. That is, the starting point of the GPS time information is January 6, 1980, 00:00:00 in UTC (Universal Coordinated Time), and the week starting on this day is the week number 0. And the receiving side is the structure which can acquire GPS time information by acquiring the data of a week number and elapsed time (second).
The week number data is data that is updated on a weekly basis.
Therefore, if the week number data is once acquired on the receiving side and the elapsed time from the time when the week number data was acquired is counted, it is acquired without acquiring the week number data again. The current week number data of the GPS satellite is known from the week number data and the elapsed time. Therefore, if the Z count data is acquired, the current GPS time can be roughly estimated. For this reason, the GPS device 40 normally acquires only the Z count data when acquiring time information.

The navigation message included in the signal from the GPS satellite has frame data (main frame configuration) of 50 bps and data with the total number of bits of 1500 bits as the main frame.
The main frame data is divided into five subframe data of 300 bits (300 bits).
One frame data corresponds to 30 seconds. Accordingly, one of the subframe data is data corresponding to 6 seconds. As described above, the first two words of each subframe data include ZLM (TOW) data of TLM word and HOW word. The Z count data starts from subframe 1 and is every 6 seconds for each subframe data. That is, subframe 1 to subframe 5 have Z count (TOW) data of TLM words and HOW words. The Z count (TOW) data is time information of the next subframe data. For example, the Z count data of subframe 1 is the time data of subframe 2.

Further, as shown in FIGS. 3 and 4, the navigation message which is a satellite signal from the GPS satellite 5 is a satellite including preamble data and HOW word TOW, each subframe data, for example, week number data and satellite health condition data. Correction data and the like, ephemeris (detailed orbit information for each GPS satellite 5), almanac (general orbit information for all GPS satellites 5), and UTC data (such as global agreement time information). More specifically, the subframe data of the navigation message is from subframe 1 to subframe 5, and the frame data is composed of these five subframe data as one unit. The subframe data is composed of 1 to 10 word data as described above.
Therefore, HOW data, that is, Z count is transmitted at intervals of 6 seconds, whereas week number data, ephemeris parameters, and almanac parameters are transmitted at intervals of 30 seconds.

Since the signal from the GPS satellite 5 is transmitted as described above, the reception of the satellite signal in the present embodiment is to make the phase synchronization with the C / A code of the satellite signal transmitted from each GPS satellite 5. .
That is, in order to acquire such frame data of the GPS satellite 5, the baseband unit 30 needs to synchronize with the signal of the GPS satellite 5.
In this case, a C / A code (1023 chip (1 ms)) is used particularly for synchronization in units of 1 ms. This C / A code (1023 chip (1 ms)) is different for each of the plurality of GPS satellites 5 orbiting the earth and is unique.
Therefore, when a satellite signal of a specific GPS satellite 5 is received, the GPS device 40 can receive it by generating a C / A code unique to the GPS satellite 5 and performing phase synchronization. Yes.
When synchronized with the C / A code (1023 chip (1 ms)), the preamble data and the HOW word of the TLM word of the subframe data can be received, and the Z count data (time information) of the HOW word can be acquired.
Furthermore, positioning information should just acquire the ephemeris parameter of a satellite signal for 3-4 satellites. Here, the ephemeris parameter can be acquired by receiving 600 bits, that is, about 12 seconds from the preamble of subframe 2 transmitted every 30 seconds.
The navigation message which is the satellite signal of the GPS satellite 5 is configured as described above.

[System configuration of reception control unit]
Next, the system configuration of the reception control unit 50 of the present invention will be described based on FIG. FIG. 5 is a functional block realized mainly by a program executed in the control unit 20.
That is, the reception control unit 50 includes a determination unit 51 and a search mode selection unit 52.

  The determination unit 51 determines the reception environment of the GPS wristwatch 1, and in this embodiment, either the multiple satellite search mode or the single satellite mode is selected by an external operation member such as the crown 6 or the buttons 7 and 8. It is configured to determine whether or not a selection operation has been performed.

  The search mode selection unit 52 captures one GPS satellite 5 and acquires time information based on a satellite signal transmitted from the GPS satellite 5 when performing reception processing by the GPS device 40 that is a reception unit. A satellite search mode and a multiple satellite search mode for acquiring a plurality of GPS satellites 5 and acquiring time information based on a satellite signal transmitted from one GPS satellite 5 among the acquired GPS satellites 5; The selection is made based on the determination result of the determination unit 51.

[Time information reception processing]
Next, the reception operation of the GPS wristwatch 1 will be described with reference to the flowchart of FIG.

  The time information reception process shown in FIG. 6 is executed when a user's reception operation is performed (during manual reception process) and when a preset reception time is reached (during automatic reception process). The set time is, for example, 2 am, 3 am, 7 am, 8 am or the like. Setting at 2am or 3am is likely that GPS wristwatch 1 has been removed from the user and placed stationary on a desk near the window in a non-wearing state, and the use of electrical products, etc. This is because there is a high possibility that the radio wave reception environment is good because the influence of noise can be reduced. The reason for setting 7:00 am or 8:00 am is the commuting time zone, because the user wearing the GPS wristwatch 1 is outdoors and easily receives satellite signals. However, the time is not limited to these times, and the user may set the automatic reception time.

  When the time information reception process is started, the determination unit 51 of the reception control unit 50 confirms whether a search mode selection operation is performed by the user (S11). If a selection operation has been performed, it is determined whether the selection operation selects a multiple satellite search mode (S12).

When the determination unit 51 determines that the selection operation of the multiple satellite search mode has been performed in S12, the search mode selection unit 52 selects the multiple satellite search mode and executes time information reception processing (S13).
On the other hand, the determination unit 51 determines “No” in S11 because the user has not performed a search mode selection operation, and “No” in S12 because the user has performed a single satellite search mode selection operation. When it is determined that the search mode selection unit 52 has selected "one satellite search mode," the time information reception process is executed (S14).

  When the search mode selection unit 52 sets the reception mode of the GPS device 40 to the one-satellite search mode, the reception control unit 50 sets the reception channel as one channel and the satellite signal transmitted from the GPS satellite 5. Reception is started (S14).

  In addition, when the reception mode of the GPS device 40 is set to the multi-satellite search mode by the search mode selection unit 52, the reception control unit 50 sets a plurality of reception channels, for example, eight channels, and transmits from the GPS satellite 5. The reception of the satellite signal to be started is started (S13).

Specifically, each reception process of S13 and S14 is performed as follows.
That is, the reception control unit 50 controls the GPS device 40 to generate a C / A code pattern of the GPS satellite 5 and start reception in order to receive a GPS signal that is a satellite signal from the GPS antenna 11. Then, the baseband unit 30 obtains a correlation value between each C / A code and the received satellite signal, and captures a GPS satellite 5 that can be synchronized.

Then, the reception control unit 50 determines whether or not the GPS satellite 5 has been captured (S15). In S15, if the satellite has not been acquired, the reception control unit 50 confirms whether the satellite acquisition time (search time) has reached a preset time (search time timeout determination time) and timed out. (S16).
The reception control unit 50 determines whether or not a timeout has occurred as follows. That is, the acquisition processing time of one satellite is about several hundred milliseconds. When the GPS wristwatch 1 performs a cold acquisition process from a state in which the GPS wristwatch 1 has not acquired orbit information (almanac parameters) of all satellites, the GPS satellites 5 are randomly searched. In this case, for example, if the search is performed in order from the No. 1 GPS satellite 5 and the No. 30 GPS satellite 5 can be acquired, that is, it takes the longest time to acquire one satellite, the satellite is detected in about 2 seconds. Can be captured. Therefore, the reception control unit 50 determines that a timeout has occurred in S16 if a satellite cannot be captured even after a preset search timeout determination time (for example, 3 seconds) has elapsed after the start of reception.

  If it is determined in S16 that the timeout has occurred, the reception control unit 50 stops the GPS reception process in the GPS device 40 (S17). Further, the reception control unit 50 displays that the reception has failed on the display 4 or the like, and the control unit 20 moves the pointer 3 based on the current internal time and displays the internal time (S18).

On the other hand, if it is determined in S15 that the satellite has been captured, the reception control unit 50 decodes the satellite signal received from the captured GPS satellite 5 and determines whether time / week information has been acquired (S19). .
In S19, the reception control unit 50 normally determines whether the Z count data and the week number data have been acquired, that is, whether the time / week information has been acquired. However, if the week number data (WN) is acquired within one week last time and there is no need to re-acquire the week number data (WN), whether or not the Z count data could be acquired in S19. You may determine only.

If it is determined in S19 that the time / week information has not been acquired, the reception control unit 50 determines whether or not the decoding time of the NAV data has timed out (S20). That is, if the time / week information cannot be acquired even after a preset time (decoding timeout determination time) has elapsed since the start of decoding of the NAV data, the reception control unit 50 has a poor reception state. to decide.
The decode timeout determination time may be set to about 12 to 24 seconds, for example, when acquiring only the Z count transmitted at 6-second intervals. On the other hand, when acquiring up to a week number transmitted at intervals of 30 seconds, it may be set to about 60 seconds to 120 seconds.

If it is determined in S20 that the time-out has not occurred, the reception control unit 50 continues to determine whether or not time / week information has been acquired (S19).
If it is determined in S20 that the timeout has occurred, the reception control unit 50 stops the GPS reception process (S17), displays that the reception has failed, and displays the current internal time. The pointer 3 is moved based on the above and the internal time is displayed (S18).

  If it is determined in S19 that the time / week information can be acquired, the reception control unit 50 stops the GPS reception process (S21), displays that the reception is successful, and displays the display 4 or the like, and the control unit 20 The pointer 3 is moved based on the acquired time information, and the display of the pointer 3 is corrected (S22).

  In the present embodiment described above, the multiple satellite search process S13 is performed only when the user manually selects the multiple satellite search mode, and in other cases, the single satellite search process S14 is performed.

[Experiment data]
Here, the time until acquisition of time information (Z count data and week number data) in one satellite search mode (single satellite mode) and multiple satellite search mode (multichannel) and experimental data relating to the acquisition rate are shown in FIG. Shown in the graph.
As shown in FIG. 7, the acquisition time of Z count data becomes shorter as the reception level is higher. For example, if the reception level is −137 dBm or more, it can be suppressed to less than 10 to 20 seconds in any mode. it can.
On the other hand, when the reception level is lowered, the acquisition time of the Z count data is also increased. For example, if the reception level is −139 dBm or less, it takes 40 to 70 seconds in any mode, and a timeout is determined in S23. Will be.

  Further, the point that the acquisition time of Z count data becomes shorter as the reception level is higher is common in each mode. However, in the satellite search mode, the acquisition rate is 80% or more when the reception level is −135 dBm or more, and when the reception level is −135 dBm or less, the acquisition rate decreases in proportion to the decrease. On the other hand, in the multiple satellite search mode, the acquisition rate is 80% or more when the reception level is −140 dBm or more, and a high acquisition rate can be maintained even at a lower reception level.

  On the other hand, the current consumption of the reception process is a relative value when the one-satellite search mode is 1, and is 1.5 to 3.0 in the multi-satellite search mode. In the multi-satellite search mode, it is about 1.5 times when the zenith is relatively empty, and about 3.0 times when the reception environment such as the room is severe.

[Effect of the embodiment]
According to this embodiment, there are the following effects.
(1) The GPS wristwatch 1 performs reception processing by selecting a single-satellite search mode and a multi-satellite search mode by a user's selection operation. For this reason, when the user determines that the reception environment is good and the reception level is high, such as outdoors, the time / week information can be acquired in a short time and the power consumption can be reduced by selecting one satellite search mode. .
On the other hand, if the user determines that the reception environment is poor, such as when receiving indoors or while walking, if the multiple satellite search mode is selected, the satellite having the highest reception level among the multiple satellites Can be received and decoded. Therefore, when the reception environment is poor, the time / week information acquisition probability can be increased compared to the case of receiving in the single satellite search mode, and the reception time can be shortened and the power consumption can be suppressed compared to the single satellite mode. it can.
Therefore, in this embodiment, since the user determines the reception environment and selects one satellite search mode or multiple satellite search mode according to the reception environment before starting reception, the average reception time is It can be shortened and power consumption can be reduced, and even when the reception environment is deteriorated, the probability that time / week information can be acquired can be increased, the restriction on the reception location is small, and convenience can be improved.
That is, if reception processing is performed only in one satellite mode, time / week information can be acquired in a short time and power consumption can be reduced when the reception environment is good and the reception level is high. However, if the reception environment deteriorates and the reception level decreases, the time / week information acquisition probability also decreases, and the satellite search process and the NAV data decoding process are repeated. Therefore, the reception time increases and the power consumption also increases. Increase.
On the other hand, if reception processing is performed only in the multi-channel mode, even when the reception environment deteriorates and the reception level is low, the acquisition probability of time / week information can be increased, and the reception time can be shortened compared to the single satellite mode. Power can be reduced. However, when the reception environment is good, the power consumption increases compared to the single satellite mode.
On the other hand, in this embodiment, the determination unit 51 and the search mode selection unit 52 are provided, and the single satellite mode and the multi-channel mode are selected by the value of the reception level, so that the average reception time can be shortened and consumed. The power can be reduced, and the probability that time / week information can be acquired can be increased even when the reception environment is deteriorated.

(2) In this embodiment, before performing the reception process, the determination unit 51 determines the reception environment, and based on the determination result, the search mode selection unit 52 selects the single satellite search mode and the multiple satellite search mode. ing.
For this reason, compared to the case where the reception process is actually performed and the search mode is dynamically selected based on the reception status, the present embodiment selects (statically) the search mode in advance before reception. Satellite signals can be received in a short time after the start of reception, and power consumption can be reduced.

(3) Since the time-out at the time of satellite capture processing is determined in S16, if the reception environment is very bad and GPS satellite 5 cannot be captured at all, it is possible to prevent useless reception processing from being continued and to reduce power consumption. It is also possible to prevent the battery voltage from being lowered and the system from going down due to the increase.
Further, since the decoding time timeout is determined in S20, it is possible to prevent the reception & decoding process from being continued unnecessarily when the reception level is low and correct time information cannot be acquired. Therefore, in this respect as well, it is possible to prevent the battery voltage from being lowered due to an increase in power consumption and system down.

(4) Since the GPS wristwatch 1 is used by being worn by a user, the GPS satellite 5 is used when a signal from the GPS satellite 5 is easily obstructed when a building such as a building is around or when walking. The reception environment is likely to change compared to a clock such as a clock fixed to a building, such as when it is difficult to receive the signal 5. The GPS wristwatch 1 of this embodiment can acquire time / week information in a short time because the user has selected the single-satellite search mode and the multiple-satellite search mode even if such a reception environment changes. And power consumption can be reduced. For this reason, the GPS wristwatch 1 of the present embodiment can be particularly suitable for a portable watch such as a wristwatch or a pocket watch.

(5) Further, in this embodiment, when the user does not perform the search mode selection operation, the one-satellite search mode which is set as the initial setting is selected. Therefore, even when the user performs a receiving operation, even if the search mode selection operation is forgotten, the reception process can be executed in the one-satellite search mode that has been initially set. For example, reception is performed when there is no search mode selection operation. The operability is not reduced as compared with the case where the processing is not performed.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. In the following embodiments, the same or similar configurations as those of the other embodiments described above are denoted by the same reference numerals, and description thereof is omitted or simplified.
In the second embodiment, as shown in the flowchart of FIG. 8, a light amount detection process for measuring the light amount irradiated to the GPS wristwatch 1 is performed, and according to the detected value, the one satellite search mode and the multiple satellite search mode are set. Is to be selected.

For this reason, the GPS wristwatch 1 according to the second embodiment includes a light amount measurement unit (not shown) that measures the amount of light applied to the GPS wristwatch 1.
Here, as the light quantity measuring unit, a light quantity sensor that directly measures the quantity of light may be provided, but in the present embodiment, a solar cell that generates power by light irradiation is provided, and the amount of light indirectly depends on the amount of power generated by the solar battery. Is measuring. That is, the GPS wristwatch 1 includes a solar cell that charges the battery 24 and a power generation detection unit that detects the amount of power generated by the solar cell, and a light amount measurement unit is configured by the solar cell and the power generation detection unit. .

In the following, the processing flow of the second embodiment will be described with reference to FIG. 8 focusing on the differences from the first embodiment.
In the second embodiment, when GPS reception is started, the light quantity measurement unit measures the amount of power generated by the solar cell (S21).
And the determination part 51 determines whether the said electric power generation amount is more than the predetermined value set beforehand (S22).
In other words, the solar cell 1 is equipped with a GPS wristwatch 1 that is placed outdoors in the daytime, and the amount of power generated is high when sunlight is irradiated. When the indoor lighting is irradiated, the solar cell is irradiated with sunlight. The amount of power generation is also lower than in the case where Moreover, when it is arrange | positioned outdoors at night, the electric power generation amount becomes low compared with the case where indoor illumination is irradiated.
Therefore, by setting a threshold value (predetermined value) that can discriminate between the power generation amount when sunlight is irradiated and the power generation amount when indoor lighting is irradiated, the power generation amount is equal to or greater than a predetermined value. If there is, the determination unit 51 can determine that the GPS wristwatch 1 is disposed outdoors. As a specific example of the threshold value, for example, a power generation amount corresponding to illuminance (light quantity) of 5000 lx (lux) may be set. That is, when it is outdoors during the daytime, the illuminance is 5000 lx or more even in rainy or cloudy weather. On the other hand, in the case of indoors, since illumination such as a fluorescent lamp is used, the illuminance is about 1000 lx or less. Therefore, the threshold for determining indoor / outdoor based on the amount of light (illuminance) may be set to about 5000 lx. Even when the amount of light is indirectly evaluated based on the amount of power generated, a power generation amount threshold corresponding to the light amount threshold is set. Then, the indoor / outdoor may be determined.

If the determination unit 51 determines No in S22, the search mode selection unit 52 selects the multiple satellite search mode and executes time information reception processing (S13).
On the other hand, if the determination unit 51 determines “Yes” in S22, the search mode selection unit 52 selects the one-satellite search mode, and executes time information reception processing (S14).
Subsequent processes S15 to S22 are the same as those in the first embodiment, and a description thereof will be omitted.

[Effects of Second Embodiment]
According to 2nd Embodiment, there can exist the same effect as said 1st Embodiment.
(6) Furthermore, since the light quantity measurement unit is provided, it can be determined that the GPS wristwatch 1 is placed outdoors if the measured light quantity is equal to or greater than a predetermined value. Therefore, it is possible to automatically determine that the reception environment is good, and it is possible to select one satellite search mode and perform reception processing.
Also, if the measured light intensity is less than a predetermined value, it is possible to automatically determine that there is a high possibility that the reception environment such as indoors is in a bad state, and it is possible to perform reception processing by selecting a multiple satellite search mode. .
Therefore, according to the present embodiment, the reception environment can be automatically and easily determined by measuring the light amount. Since the single-satellite search mode or the multiple-satellite search mode can be selected according to the determined reception environment, the average reception time can be shortened, the power consumption can be reduced, and even when the reception environment is deteriorated, the time / The probability that week information can be acquired can be increased, the restriction on the receiving location is small, and the convenience can be improved.

[Third Embodiment]
Next, a third embodiment of the present invention will be described with reference to FIG.
In the GPS wristwatch 1 of the third embodiment, satellite orbit information (almanac) is stored in the storage unit 20A. The satellite orbit information (almanac) is received from the satellite signal periodically, for example, once a week.
Then, as shown in the flowchart of FIG. 9, the determination unit 51 recognizes the orbit information of the GPS satellite 5 that can currently receive satellite signals from the current time information and position information and the satellite orbit information. And the elevation angle of each GPS satellite 5 is detected (S31).

In addition, what is necessary is just to refer to the time information of the internal clock of the GPS wristwatch 1 for the current time information.
Further, as the position information, information obtained by position information acquisition processing for receiving satellite signals from a plurality of GPS satellites 5 and obtaining the current location may be stored, and the position information may be referred to. This position information acquisition process is normally performed by a user's manual operation when changing the time zone, such as when traveling overseas.

Then, the determination unit 51 determines whether or not there are a predetermined number or more of GPS satellites 5 whose elevation angle is at a high elevation angle equal to or greater than a predetermined angle (S32). In S32, for example, it is determined whether there are three or more GPS satellites 5 having an elevation angle of 60 degrees or more.
If the determination unit 51 determines No in S32, the search mode selection unit 52 selects the multi-satellite search mode and executes time information reception processing (S13).
On the other hand, when the determination unit 51 determines “Yes” in S32, the search mode selection unit 52 selects the one-satellite search mode, and executes time information reception processing (S14).
Subsequent processes S15 to S22 are the same as those in the first embodiment, and a description thereof will be omitted.

[Effect of the third embodiment]
According to 3rd Embodiment, there can exist the same effect as said 1st Embodiment.
(7) Furthermore, since the orbit information (almanac) of each GPS satellite 5 is stored in the storage unit 20A, in the currently receivable GPS satellites 5, is there a predetermined number or more of GPS satellites 5 whose elevation angle is equal to or greater than a predetermined value? Whether or not the reception environment is good can be easily determined.
Therefore, the reception environment can be automatically determined based on the satellite orbit information, and the single satellite search mode or multiple satellite search mode is selected according to the reception environment, so the average reception time can be shortened and the power consumption is also reduced. In addition, even when the reception environment is deteriorated, the probability that time / week information can be acquired can be increased, the restriction on the reception location is small, and the convenience can be improved.

[Fourth Embodiment]
Next, a fourth embodiment of the present invention will be described with reference to FIG.
The GPS wristwatch 1 of the fourth embodiment includes a reception level detection unit that detects the reception level of a satellite signal, and the storage unit 20A stores the previous reception level detected by the reception level detection unit.
Then, as shown in the flowchart of FIG. 10, the determination unit 51 confirms the previous reception level with reference to the storage unit 20A during the reception process (S41).

Then, the determination unit 51 determines whether the confirmed reception level is equal to or higher than the previous reception level (S42). For example, it is determined whether or not the previous reception level is a predetermined value (for example, −133 dBm) or more.
If the determination unit 51 determines No in S42, the search mode selection unit 52 selects the multiple satellite search mode and executes time information reception processing (S13).
On the other hand, when the determination unit 51 determines “Yes” in S <b> 42, the search mode selection unit 52 selects the one-satellite search mode and executes time information reception processing (S <b> 14).
Subsequent processes S15 to S22 are the same as those in the first embodiment, and a description thereof will be omitted. If the time / week information can be acquired in S19, the reception control unit 50 stores the reception level in the storage unit 20A (S43).

[Effect of Fourth Embodiment]
According to 4th Embodiment, there can exist the same effect as said 1st Embodiment.
(8) Further, since the previous reception level is stored in the storage unit 20A and the reception environment is determined based on whether or not the previous reception level is equal to or higher than a predetermined value, it is determined whether or not the reception environment is good. Easy to judge before receiving.
Therefore, the reception environment can be automatically determined according to the previous reception level, and the single satellite search mode or the multiple satellite search mode is selected according to the reception environment, so that the average reception time can be shortened and the power consumption is also reduced. In addition to the reduction, it is possible to increase the probability that the time / week information can be acquired even when the reception environment is deteriorated, and there are few restrictions on the reception place, and convenience can be improved.

[Modification]
The present invention is not limited to the above embodiments.
In the present invention, the method for determining the reception environment is not limited to those described in the above embodiments.

For example, the GPS wristwatch 1 may include a movement speed detection unit that detects the movement speed of the GPS wristwatch 1. As the moving speed detection unit, for example, a speed sensor such as an acceleration sensor may be used. For example, when determining by measuring acceleration, if the maximum acceleration per unit time when the casing is swung in two directions in the vertical direction is greater than or equal to a threshold value of 0.98 m / s ² (0.1 G), walk If it is less than the threshold, it can be determined that the object is stationary. That is, the maximum acceleration of the housing when walking or jogging is performed with the timing device attached to the arm is 4.9 to 9.8 m / s ² (0.5 to 1.0 G). Therefore, it can be determined whether the timing device is in a moving state or a stationary state depending on whether or not the measured maximum acceleration is equal to or greater than the threshold value.
When such a moving speed detection unit is provided and the detected speed is as low as a predetermined value (threshold value) or less, there is a high possibility that the reception environment is better than when the detected speed is higher than the predetermined value. That is, when receiving a satellite signal from the GPS satellite 5, it becomes difficult to receive the satellite signal if the positional relationship between the GPS satellite 5 and the GPS wristwatch 1 changes. Therefore, if the movement speed of the GPS wristwatch 1 is increased, the reception environment is deteriorated. Therefore, when the movement speed is higher than a predetermined value, the multiple satellite search mode in which the reception sensitivity becomes higher is selected and the movement speed is predetermined. If it is less than the value, if one satellite search mode is selected, the average reception time can be shortened, power consumption can be reduced, and time / week information can be acquired even when the reception environment is deteriorated. Probability can be increased, reception place restrictions are small, and convenience can be improved.

The GPS wristwatch 1 stores the reception time at the time of the reception process in the storage unit 20A, and the determination unit 51 refers to the storage unit 20A at the time of the reception process to check the previous reception time, and receives the reception time. If the time is less than or equal to a predetermined time (threshold), the single satellite search mode may be selected, and if the time is longer than the predetermined time, the multiple satellite search mode may be selected.
When the previous reception time is short, it can be determined that the reception environment is good, and there is a high possibility that the current reception environment is also good. That is, when the automatic reception process is performed, the next automatic reception is usually received at the same time, so the reception environment is often in the same state. When manual reception processing is performed, the user often performs a reception operation in a similar reception environment.
Therefore, in both cases of automatic reception and manual reception, the previous reception environment and the current reception environment are often the same. Therefore, if the previous reception time is short, there is a high possibility that the reception environment will be good at the next reception, so the single satellite search mode may be selected. On the other hand, if the previous reception time is long, there is a high possibility that the reception environment will be bad at the next reception, so the multiple satellite search mode may be selected.
Note that the threshold for determining the reception time may be set to, for example, 1 minute when receiving only the Z count data, and 3 minutes when receiving calendar information such as a week number. As described above, since the Z count data can be received at intervals of 6 seconds, it can be determined that the reception environment is bad when the reception time is as long as 1 minute or longer. In addition, since week numbers can be received at 30-second intervals, depending on the reception start timing, reception may take 1 minute or more even if the reception environment is good. For this reason, it is preferable to set the threshold value longer than that in the case of Z count data. For example, the threshold value may be set to about 3 minutes.

  Furthermore, as a determination method of the reception environment, a plurality of determination methods described in the above embodiments and modifications may be combined. For example, even if it is determined that the detected light amount is a predetermined value, that is, the GPS wristwatch 1 is outdoors, by combining the determination based on the light amount detection and the determination based on the moving speed, the moving speed is greater than the predetermined value, that is, the GPS wristwatch 1 is moving. In this case, it may be determined that the reception environment is not so good and the multiple satellite search mode is selected.

Further, in each of the above embodiments, the first time reception immediately after power-on may be configured to always select the multiple satellite search mode regardless of the determination result of the determination unit 51.
Immediately after the power is turned on, there is a high possibility that the time of the clock is shifted, so it is necessary to reliably receive the time information. For this reason, if the multiple satellite search mode is selected when the first time is received immediately after the power is turned on, the possibility that the time information can be reliably acquired is improved, and the time of the GPS wristwatch 1 can be corrected correctly.

Further, the specific time-out determination time (search time-out determination time, multiple search time-out determination time, decode time-out determination time) in each of the above embodiments is not limited to the above-described embodiment, and may be set as appropriate in implementation.
Furthermore, the threshold value in each of the embodiments and the modified examples is not limited to the value of the illustrated specific example, and may be set to a value that can determine each state in the implementation.

Furthermore, the time measuring device is not limited to that incorporated in the GPS wristwatch 1. For example, it may be incorporated in a mobile phone.
Each of the above-described embodiments has been described with respect to GPS satellites. However, the present invention is not limited to GPS satellites, but is limited to other global navigation satellite systems (GNSS) such as Galileo and GLONASS, SBAS, A position information satellite that transmits a satellite signal including time information such as a zenith satellite may be used.

It is the schematic which shows the wristwatch with GPS which concerns on this invention. It is a block diagram which shows the circuit structure of the wristwatch with GPS of FIG. It is a schematic conceptual diagram for demonstrating the structure of a GPS satellite signal. It is a schematic explanatory drawing which shows a GPS satellite signal. It is a block diagram which shows the structure of the reception control part of 1st Embodiment. It is a flowchart which shows the reception process of 1st Embodiment. It is a graph which shows the relationship between the signal strength of a satellite signal, an acquisition rate, and acquisition time. It is a flowchart which shows the reception process of 2nd Embodiment. It is a flowchart which shows the reception process of 3rd Embodiment. It is a flowchart which shows the reception process of 4th Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... GPS wristwatch, 3 ... Pointer, 4 ... Display, 5 ... GPS satellite, 11 ... GPS antenna, 18 ... Reception circuit, 20 ... Control part, 20A ... Memory | storage part, 27 ... RF part, 30 ... Baseband part, DESCRIPTION OF SYMBOLS 40 ... GPS apparatus, 43 ... Drive circuit, 44 ... Time adjustment apparatus, 45 ... Time display apparatus, 50 ... Reception control part, 51 ... Determination part, 52 ... Search mode selection part.

Claims (10)

A receiver that captures a location information satellite and receives a satellite signal transmitted from the captured location information satellite;
A time information generating unit that generates time information based on the satellite signal received by the receiving unit;
A time display unit for displaying time information;
A timing control device comprising a reception control unit for controlling the reception unit,
The reception control unit
A determination unit for determining a reception environment in the timing device before performing the reception process;
When performing the reception process by the receiving unit, a single satellite search mode for capturing one position information satellite and acquiring time information based on a satellite signal transmitted from the position information satellite, and a plurality of position information satellites A plurality of satellite search modes for acquiring time information based on a satellite signal transmitted from one position information satellite among the captured plurality of position information satellites are selected based on a determination result of the determination unit. A timekeeping device comprising a search mode selection unit. The timing device according to claim 1,
Equipped with a light quantity measurement unit that measures the amount of light emitted to the timing device,
The determination unit determines whether or not the light amount measurement unit has measured a light amount greater than or equal to a predetermined value,
The search mode selection unit selects the one-satellite search mode when the determination unit determines that the light amount of a predetermined value or more is measured, and when the determination unit determines that the light amount of less than the predetermined value is measured, A clock device characterized by selecting a multiple satellite search mode. The timing device according to claim 1,
It has a moving speed measurement unit that measures the moving speed of the time measuring device,
The determination unit determines whether or not the moving speed measurement unit has measured a moving speed equal to or lower than a predetermined value,
The search mode selection unit selects the one-satellite search mode when the determination unit determines that the moving speed of a predetermined value or less is measured, and determines that the moving speed greater than the predetermined value is measured. Selects the multiple satellite search mode. The timing device according to claim 1,
A storage unit for storing orbit information of the position information satellite;
Based on the orbit information stored in the storage unit, the determination unit includes a predetermined number or more of position information satellites located at a high elevation angle of a predetermined angle or more among position information satellites that can be captured at the time of performing reception processing. Whether or not
The search mode selection unit selects the one-satellite search mode when the determination unit determines that there are a predetermined number or more of position information satellites positioned at the high elevation angle, and determines that the number is less than the predetermined number. In this case, the time counting device is characterized in that the multiple satellite search mode is selected. The timing device according to claim 1,
A reception level detection unit for detecting the reception level of the satellite signal received from the position information satellite;
A storage unit for storing the reception level detected by the reception level detection unit,
The determination unit determines whether the reception level at the previous reception stored in the storage unit is a predetermined value or more,
The search mode selection unit selects the one-satellite search mode when the determination unit determines that the reception level at the previous reception is equal to or higher than the predetermined value, and determines that the reception mode is lower than the predetermined value The time measuring device is characterized in that the multiple satellite search mode is selected. The timing device according to claim 1,
A reception time measurement unit for measuring a reception time from receiving a satellite signal from a position information satellite to obtaining time information;
A storage unit for storing the reception time measured by the reception time measurement unit,
The determination unit determines whether or not the reception time at the previous reception stored in the storage unit is a predetermined time or less,
The search mode selection unit selects the one-satellite search mode when the determination unit determines that the reception time at the previous reception is equal to or shorter than the predetermined time, and determines that the search mode selection unit is longer than the predetermined time. Selects the multiple satellite search mode. The timing device according to claim 1,
Provided with an external operation member that can be operated by the user,
The determination unit determines whether a selection operation of one satellite search mode or multiple satellite search mode has been performed on the external operation member,
The search mode selection unit selects the one-satellite search mode when the determination unit determines that a single-satellite search mode selection operation has been performed, and determines that a multiple-satellite search mode selection operation has been performed. In this case, the time counting device is characterized in that the multiple satellite search mode is selected. The timing device according to claim 7,
The search mode selection unit selects the single satellite search mode when the determination unit determines that neither the single satellite search mode nor the multiple satellite search mode is selected. apparatus. In the time measuring device in any one of Claims 1-8,
The search mode selection unit selects a multi-satellite search mode regardless of a determination result of the determination unit when performing time reception processing for the first time after the timing device is turned on. Timing device. A receiver that captures a location information satellite and receives a satellite signal transmitted from the captured location information satellite;
A time information generating unit that generates time information based on the satellite signal received by the receiving unit;
A time display unit for displaying time information;
A satellite signal reception method of a timing device comprising a reception control unit for controlling the reception unit,
A determination step of determining the reception environment in the timing device before performing the reception process;
When performing the reception process by the receiving unit, a single satellite search mode for capturing one position information satellite and acquiring time information based on a satellite signal transmitted from the position information satellite, and a plurality of position information satellites A plurality of satellite search modes for acquiring time information based on a satellite signal transmitted from one position information satellite among the captured plurality of position information satellites are selected based on a determination result of the determination unit. A search mode selection step;
A satellite signal receiving method for a time measuring device.

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