JPH1082875A - Electronic watch and clocking content correcting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the power consumption and extend the operating time for battery drive by intermittently receiving signals containing the time information from a position measuring satellite, extracting the time information, and correcting the clocking content of a clocking means. SOLUTION: The GPS antenna signal is frequency-converted (1) by the signal generated by a VOC 2 and converted into digital data (4). A carrier NCO 6 generates the frequency signal based on the control data a CPU 10, and a multiplier 5 multiplies the output data 4, 6 and generates the signal removed with the carrier component. A PRN code generating circuit 8 generates the C/A code specified by the data of the CPU 10 in the specified phase, and a correlator 7 correlates the carrier removal signal and the C/A code. The CPU 10 reads, calculates, and feeds the correlated data to the circuits 8, 6 to synchronize the C/A code phase and the carrier frequency. The navigation message data are extracted, the present time is obtained from the contained time information, and the clocking content of a clocking circuit 16 and the timer clocking content of a control circuit 15 are corrected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic timepiece for receiving a radio wave transmitted from a positioning satellite such as a GPS satellite to obtain a current date and time, and a method for correcting a clock content.

[0002]

2. Description of the Related Art Conventionally, in a positioning system such as a GPS, information for observing a distance from each positioning satellite to a receiving point and information for calculating a position of each positioning satellite have been transmitted. The receiver obtains the position of each positioning satellite and the distance from each positioning satellite to the receiving point by using the positioning signals from the number of positioning satellites required for three-dimensional positioning, and obtains each of these positioning satellites. And the distance from each positioning satellite to the receiving point, the position of the receiving point is obtained.

In such a positioning system, a time system for unifying the time system in the system (GPS time in a GPS system) is set, and information for obtaining the time in the time system is transmitted from the satellite. Is included in the signal. Therefore, a receiver that receives such a signal
It also has a clock function in addition to positioning purposes. In the GPS system, the clock on the satellite is an electronic clock, and the length of one second is substantially equal to one second of the atomic time, which is the same as Coordinated Universal Time (hereinafter referred to as “UTC”). Therefore, an extremely accurate electronic timepiece can be constructed by receiving signals from the positioning satellite.

[0004]

However, in order to receive a signal from a positioning satellite and use it as a clock, power consumption becomes a problem. That is, when used as a positioning device, it is basically necessary to energize only when performing positioning,
If you use it as a clock, you will always receive it,
When the battery is driven for a long period of time, a large-capacity battery is required. SUMMARY OF THE INVENTION It is an object of the present invention to provide an electronic timepiece capable of keeping the entire power consumption low and, for example, maintaining a long operation time in the case of battery operation, and a method for correcting the timekeeping content therefor.

[0005]

An electronic timepiece according to the present invention includes a means for counting a reference clock signal to measure time or to generate a timing signal having a fixed period, and a positioning satellite. Means for intermittently receiving a signal containing time information to be transmitted, extracting time information, and correcting the content of timekeeping of the timekeeping means. According to a seventh aspect of the present invention, there is provided a timekeeping content correcting method for counting a reference clock signal to perform timekeeping or generation of a timing signal having a constant period, and for obtaining time information transmitted from a positioning satellite. The received time signal is intermittently received and time information is extracted to correct the content of the time measurement or the generation timing of the timing signal. By intermittently receiving the signal including the time information transmitted from the positioning satellite in this way, only the power consumption for time measurement is performed during the non-reception period, and the overall average power consumption is suppressed. In addition, since the reference clock signal is counted to measure the time or generate a timing signal having a constant period, the accuracy is basically determined by the accuracy of the reference clock signal.
Since the timing information or the timing of the generation of the timing signal is intermittently corrected by the time information extracted by receiving the signal from the positioning satellite, the average accuracy is greatly improved, and the predetermined accuracy is improved. It is possible to suppress power consumption while maintaining.

The electronic timepiece according to the present invention counts a reference clock signal and measures time or generates a fixed period timing signal. The electronic timepiece transmits time information transmitted from a positioning satellite. Means for intermittently receiving a signal including the clock bias, and extracting a clock bias component and a drift component of the content of the time counted by the timing device; and Means for intermittently correcting the drift together with the correction. Further, according to the present invention, the timekeeping content correction method counts a reference clock signal to perform timekeeping or generation of a timing signal having a constant period, and also uses time information transmitted from a positioning satellite. The clock signal and the drift of the content of the time are extracted by intermittently receiving the signal including the clock, and the drift and the correction of the clock bias are corrected with respect to the content of the time or the generation timing of the timing signal. Is performed intermittently. By intermittently receiving the signal including the time information transmitted from the positioning satellite in this way, only the power consumption for time measurement is performed during the non-reception period, and the overall average power consumption is suppressed. In addition, since the reference clock signal is counted to measure the time or generate a timing signal with a fixed period, the accuracy is basically determined by the accuracy of the reference clock signal, but the clock bias component and the drift component of the clock content are extracted. Since the correction of the clock bias and the correction of the drift for the timing content or the timing of the generation of the timing signal are performed, the time error from the reception of the signal from the positioning satellite to the next reception is also reduced. Can be suppressed. For example, if the error due to the drift component is intermittently estimated and corrected without performing reception during the time from the correction of the current clock bias to the correction of the next clock bias, even during the next reception. High accuracy can be maintained.

In the electronic timepiece according to the present invention, the intermittent period is set such that the correction amount of the content of the clock by the clock means is less than a predetermined value. As a result, regardless of the accuracy of the reference clock signal, the time can be measured or the timing signal can be generated with the required timing accuracy.

The electronic timepiece according to the present invention includes a means for detecting a timing at which time information is superimposed on a signal transmitted from the positioning satellite, and sets the intermittent period to the time of the next reception. Means for automatically determining the time when the time information is received.
As a result, time information superimposed on a signal transmitted from a positioning satellite can be efficiently received, and power consumption can be suppressed to a minimum. For example, GPS
In the case of, the UTC parameter is described on page 18 of frame 4 in the navigation message, and is repeatedly broadcast at a cycle of 12.5 minutes. The reception may be performed intermittently at intervals.

According to a fifth aspect of the present invention, there is provided an electronic timepiece including a reception possibility determining means for determining a reception possibility of a signal from each positioning satellite in each time zone, and A means is provided for automatically determining a time zone in which a signal from a positioning satellite can be received at the time of next reception. As a result, when the receiving operation is intermittently repeated, the signal from the positioning satellite can be reliably received at the next reception, so that the correction of the timekeeping content does not fail and the required accuracy is maintained. be able to.

In the electronic timepiece according to the present invention, the reception possibility determining means stores, for each time zone, positioning satellites that have been successfully received in each time zone, and further comprises a predetermined time interval. The determination is made based on the presence or absence of a positioning satellite that has been successfully received in the band in the past. For example, GPS
In the case of, each positioning satellite appears at the same position in a fixed cycle as viewed from the reception point (appears relatively at the same position as viewed from the reception point in 23 hours and 56 minutes). If the satellite is present in the field of view, it is possible to automatically determine the next receivable reception timing if it is prepared in advance in a table or the like. Thereby, even if the orbit information of each satellite is unknown, it is possible to determine the receivability based on the presence or absence of a positioning satellite that has been successfully received in the past.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of an electronic timepiece according to an embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is a block diagram showing the configuration of the electronic timepiece. In FIG. 1, a VCO 2 generates a local oscillation frequency signal based on a reference signal generated by a reference signal oscillator 3, and a frequency conversion circuit 1 uses a signal generated by the VCO 2 to generate a GPS signal.
The signal from the antenna is frequency-converted. The AD converter 4 converts this into digital data. Carrier NC
O6 generates a signal of a frequency based on the control data from the CPU, and the multiplier 5 multiplies the output data of the AD converter 4 by the output data of the carrier NCO 6 to generate a signal from which the carrier component has been removed. CPU 10 is I / O
The C / A code and its phase data are supplied to PRN code generation circuit 8 via port 9. In response, PRN code generation circuit 8 generates a designated C / A code at a designated phase. The correlator 7 determines whether the signal from which the carrier has been
/ A code is correlated. The CPU 10 reads the correlation data via the I / O port 9. The counter 14 counts the time in a 6 second cycle on the receiver side.
Counting is performed at intervals shorter than 1 ms. The counter 14 generates an interrupt signal every 5 ms and generates a signal per second (hereinafter referred to as "1 PPS"). The counter 14 always operates with the backup power supply, not only when the main power supply is on, but also when the main power supply is off. Although only one channel is shown in the example shown in FIG. 1, when a plurality of channels are provided, at least the carrier NCO
6, a multiplier 5, a PRN code generation circuit 8 and a correlator 7 are provided for each reception channel, and the CPU 10 searches and tracks a plurality of satellites simultaneously using the plurality of reception channels. However, if only an electronic watch is used without performing receiving point positioning, or if positioning is performed and the moving speed of the receiving point is low, only one receiving channel is required. The control circuit 15 is used for switching between a sleep mode and a full power mode and performing a wake-up operation, and includes a timer for measuring GPS time. Here, the full power mode means that the CPU
10 is a mode in which each unit operates by this, and the sleep mode is a mode in which the CPU 10 stops the operation,
In this mode, the control circuit 15, the counter 14, and the clock circuit 16 operate and the RAM 12 is backed up. The control circuit 15 receives the setting data of the full power mode and the sleep mode from the CPU and controls on / off of the switch 17. Reference numeral 18 denotes a battery power source serving as a main power source, and the switch 17 is turned on in a full power mode. Reference numeral 19 denotes a backup battery power supply. In the sleep mode, the control circuit 15, the counter 14, and the clock circuit 16, which will be described later, continue to operate with this power supply.
AM 12 is backed up. The control circuit 15 is C
The GPS time data is received from the PU 10 at a predetermined timing and set in a timer, and then the timer counts the 1PPS signal to measure the GPS time. Further, the control circuit 15 receives the data of the wake-up time from the CPU 10 and stores it, and when the content of the timer matches the data, turns on the switch 17 to set the full power mode. The clock circuit 16 includes a display unit for displaying the UTC time or a local time obtained by adding a time difference to the time in the format of year, month, day, hour, minute and second, and a counter for counting 1 PPS. After setting the counter at a predetermined timing, 1PPS is counted and the current time is always displayed. CPU 10 is RO
The program written in advance in M11 is executed, the correlation data from the correlator 7 of each reception channel is read, a predetermined loop filter operation is performed, and C / A is performed for each PRN code generation circuit 8 and each carrier NCO6. By providing the code phase data and the carrier frequency data, respectively, the synchronization with the C / A code phase and the carrier frequency is obtained, and the navigation message data is extracted. Further, the current time is obtained from the time information included in the navigation message, and the clock content of the clock circuit 16 and the clock content of the timer in the control circuit 15 are corrected. Also CPU
Reference numeral 10 extracts satellite orbit information (ephemeris) from the navigation message data, obtains the position information of each satellite from the time when the C / A code phase is obtained and the orbit information of the satellite, and obtains the position information of each satellite and C The position of the receiving point is calculated from the / A code phase (pseudo distance). The data transmission interface 13 is an interface circuit for transmitting various data.
, And time information and information on the positioning result are transmitted to the host device. Of course, when only the electronic timepiece shown in FIG. 1 is used alone, such a data transmission interface is not necessary.

FIG. 2 is a block diagram showing the configuration of the counter 14 shown in FIG. 1. In FIG. 2, a free-run counter 31 is a counter that counts a reference clock signal at intervals shorter than 1 ms. This is a circuit that holds the 1PPS correction amount given from the CPU. The comparison circuit 32 outputs 1PPS when the value of the free-run counter 31 becomes equal to the value of the latch circuit 33. Therefore, the generation timing of 1PPS changes according to the 1PPS correction amount set in the latch circuit 33. The CPU calculates the value of the free-run counter 31 at the timing of 1PPS to be output next, and sets a value equal to the value to the latch circuit 33. As a result, the corrected accurate 1 is obtained without correcting the value of the free-run counter 31 itself.
Output PPS. For example, if the high-order digit of the free-run counter 31 repeats counting every 1 ms between 0 and 5999, and the clock offset (described later) is 550 when represented by the count value of the free-run counter, the latch 550 is set in the circuit 33. Thereby, when the count value of the free-run counter reaches 550, 1PPS is generated. Next, the latch circuit 33
Is set to 1550, 1PPS is generated when the count value of the free-run counter reaches 1550. Next, 2550 is set in the latch circuit 33, and when the count value of the free-run counter reaches 2550, 1 is set.
Generate PPS. Thereafter, the correct 1PPS is generated by changing the 1PPS correction amount for the latch circuit in the same manner.

FIG. 3 is a diagram showing the relationship between the timing of satellite search and time calculation and the time accuracy. As shown in the figure, immediately after the power is turned on, the satellite search and the time calculation are performed in the full power mode. If one satellite has been acquired after power-on and navigation messages have been collected, GP based on the time-related data contained in the navigation messages
S time is calculated. In the case of one satellite, the radio wave propagation delay time between the satellite and the receiving point is unknown, so that the time can be obtained with an accuracy of ± 10 ms by using the average radio wave propagation delay time. If three or more satellites are captured and the radio wave propagation delay time between the receiving point and each satellite becomes clear, the time is determined with a time accuracy of 1 ms. Therefore, the output of 1 PPS is started by the operation of the counter 14 thereafter. After the time is determined, the sleep mode is set, and only the counter 14, the control circuit 15, and the clock circuit 16 continue to operate, and the other circuit parts are in the sleep state, so that power consumption is suppressed. The sleep time is determined according to the accuracy of the reference clock signal given to the free-run counter and the required accuracy as a clock, except for the conditions described later. For example, if the accuracy of the crystal that generates the reference clock signal is 3 ppm (3 × 10 ⁻⁶ ), the accuracy is required to be 10 m because the maximum deviation is about 9 ms in about 50 minutes.
s ((1 ms of required time accuracy) + (9 m of shift amount)
If it is less than s)), the satellite search and time calculation should be performed again in the full power mode within about 50 minutes to obtain and correct the accurate current time. Therefore, in this case, the sleep time may be set within 50 minutes. After the elapse of the sleep time, the wake-up, that is, the full power mode is performed, a signal from the satellite is received, and the time is corrected when an accurate time is obtained. After the wake-up, it takes a certain time (for example, one minute) until an accurate time is obtained. Therefore, the sleep time may be set so that the wake-up is performed earlier by this time. As will be described later, during the time from the time determination or time correction to the next time correction, it is not necessary to keep the sleep mode continuously, and the necessary processing other than the reception processing can be repeatedly performed in a short time. You may.

FIG. 4 is a diagram showing a configuration of a navigation message included in a signal transmitted from a GPS positioning satellite. The navigation message is data having a bit rate of 50 bps and a total frame number of 1500 bits as a main frame. The main frame is divided into five 300-bit subframes (subframe 1, subframe 2, subframe 3, subframe 4, and subframe 5). Therefore, one frame corresponds to 30 seconds, and each sub-frame corresponds to 6 seconds. As shown in the figure, each subframe counts the time elapsed from the reference time of GPS time referred to as Z count (0:00 UTC on January 6, 1980) in a one-week cycle in units of 6 seconds. (The time count value from the start of each week to the end timing of the subframe). Subframe 1 includes a week number from a reference date for GPS (Jan. 6, 1980) and a satellite clock correction coefficient. The page 18 of the subframe 4 includes a difference between the GPS time and the UTC (cumulative leap second) and a UTC parameter which is data for leap second adjustment. That is, the UTC parameter includes the current leap second Δt _LS before or after the leap second adjustment, the scheduled leap second adjustment week number WN _LSF , the leap second adjustment scheduled day number DN, and the leap second adjustment to be performed in the future or already performed Cumulative leap second Δt
_{Consists of LSF} . The Z count, the week number, the UTC parameter, and the correction amount of the satellite clock are time-related data.

FIG. 5 is a diagram showing the relationship between the GPS system time on the satellite side, the GPS system time on the receiver side, and the time count. The GPS system time on the satellite side is a system time for counting 6 seconds of the subframe shown in FIG. The GPS system time on the receiver side is a time period of 6 seconds with the start position of the subframe being 0 second, and is delayed from the GPS system time on the satellite side by the propagation delay time of the radio wave between the satellite and the receiver. . "Time count" in the figure is the value of the free-run counter 31 shown in FIG. When the head position of the sub-frame is set to 0 second and the GPS system time on the receiver side is made to coincide with the GPS system time on the satellite side, the value of the time counter is not directly corrected. The deviation is stored as a clock bias. The difference between the GPS system time on the satellite side and the time count of less than one second is the clock offset described above, and as described above, the latch circuit 3 shown in FIG.
By making the 1PPS correction amount given to 3 a value in consideration of the clock offset, 1PPS synchronized with the GPS system time on the satellite side is generated.

FIG. 6 is a flowchart showing the overall processing procedure of the electronic timepiece. First, when the power is turned on, the full power mode is set, and the setting for satellite search is performed. The satellite search process is performed in parallel by another process (not shown) performed by the CPU.
/ A code and its phase data are shown in FIG.
The correlation data is supplied to the code generation circuit 8, the correlation result from the correlator 7 is read, the phase data of the C / A code is changed accordingly, and this processing is repeated to detect the phase at which the correlation data reaches a peak. If tracking of one or more satellites is performed by the satellite search processing (not shown), a navigation message is collected from the received signal, the time-related data is extracted from the navigation message, and the GPS is determined based on the time-related data. Calculate the time. The processing for positioning is performed in parallel by another processing (not shown) of the CPU. At this time, if the positioning of the receiving point has not been performed yet, and the radio wave propagation delay time from the receiving point to the satellite is unknown, the average value of the radio wave propagation delay time is ± 10%.
The GPS time is obtained with an accuracy of ms. Next, this GPS
The time is written to the timer of the control circuit 15. As a result, the timer measures the GPS time each time 1 PPS is received thereafter. Subsequently, it is determined whether the UTC parameter is valid. If the difference between the current update time and the current update time of the current UTC parameter collected and updated from the navigation message is, for example, within 6 days, the UTC parameter is considered valid. If UTC parameters are extracted from the above navigation message by this reception, or if UTC parameters within 6 days have been collected and updated by previous reception, the GPS time is corrected for leap second and UT is corrected.
The C time is calculated, and a time difference is added thereto to obtain a local time (standard time in the local area). The time data is transmitted to the outside via the data transmission interface 13 as needed. Thereafter, the next wake-up time Tup is calculated, and the calculated wake-up time Tup is set in the control circuit and the sleep mode is set. As a result, until the next wake-up time Tup is reached, most of the time, except for an interrupt process every 5 ms, which will be described later, is in the sleep state. After that, when the wake-up time Tup comes, the control circuit 15 turns on the switch 17 to switch to the full power mode. As a result, the CPU is started, and the processing shown in FIG. 6 is executed again. If the UTC parameters have not been collected yet or are invalid, the UTC parameters are collected from the navigation message from the satellite received by the next wake-up.

FIG. 7 shows the next wake-up time Tu.
9 is a flowchart illustrating a procedure for calculating p. If valid UTC parameters have not yet been collected and updated,
A time Tup1 required for collecting and updating UTC parameters is calculated. This is performed based on the fact that the description position of the UTC parameter in the navigation message (page 18 of the subframe 4) is determined and the repetition period of the navigation message is constant, as described later. Subsequently, it is determined whether or not the satellite can be captured at the time Tup1 by referring to a captured satellite table (FIG. 10) described later. If not, a time at which the satellite can be captured is determined. This is determined as the next wake-up time Tup. If valid UTC parameters have already been collected and updated, the previous wake-up time Tup
Then, a value obtained by adding the sleep time for satisfying the required accuracy required is calculated as the next wake-up time Tup2. For a sleep time for satisfying the required accuracy required, for example, a table set in advance as shown in FIG. 8 is referred to. In this example, for example, when the required accuracy is 2 ms (assuming acquisition of three satellites or more), the sleep time is set to 4 minutes. For example, if the required accuracy is 20 ms, the sleep time is set to 104 minutes. And that Tup
In 2, it is determined whether or not the satellite can be captured with reference to a captured satellite table (FIG. 10) described later. It is determined as the wake-up time Tup.

Note that the required accuracy is Pd [s], the accuracy of the time obtained by reception is Po [s], the accuracy of the original oscillation frequency for generating the reference clock signal is Pc (unitless), and the reception accuracy after wake-up is accurate. Assuming that the time required until a proper time is obtained is Tr [s] and the sleep time is Ts [s], the relationship of Pd−Po = (Ts + Tr) · Pc is established. The table shown in FIG.
It was previously determined from the above relationship, assuming that × 10 ⁻³ , Pc = 3 × 10 ⁻⁶ , and Tr = 60. Since the above variables are known in this way, they may be calculated at a necessary time without using a table.

FIG. 9 is a diagram showing a schedule for collecting UTC parameters. The time for collecting the UTC parameter is obtained as follows.

The current GPS time is read from the timer of the control circuit. For example, Sunday, July 21, 1996
00:12:00.

The current time is converted to GPS time (second) Tnow.

In the above example, Tnow = 863 × 604800 + 12
Calculate as × 60. Here, 863 is the week number at the date and time, and 604800 is the number of seconds in one week.

Taking the time (for example, 60 seconds) necessary for satellite search and tracking into account, the wake-up time Tup
Ask for.

Tw = Tnow / 604800 tz = (Tnow mod 604800- (528-60)) / 750 + 1 tz '= tz * 750 + (528-60) Tup = tw * 604800 + tz' This is an integer variable, and any decimal places are truncated. The above mod is an operator for finding the remainder. In the above example, Tup = 863 * 604800 + (750+
(528-60)). This is 199 if converted to date
It is 00:20:18 on July 21, 2006.

In this example, all times are managed by GPS time, but may be managed by using UTC time.

FIG. 10 is a table used to determine whether satellite acquisition is possible at the next wake-up time. Here, 24 hours a day (86400 seconds equals 4
Create a table divided into minutes, and set the division number from 0 to 3
The time count is up to 59 (86400 / (4 * 60) = 360).

The procedure for writing data to this table is as follows.

From the difference between the current date and the reference date for calculating the table, a time count for advancing by 4 minutes per day is calculated.

Time count = (reference date-current date) +00: 00: 00: 00 In the example shown in FIG. 10, since the reference date is July 21, 1996, for example, the time on July 23, 1996 The count is -2.

The time count is normalized between 0 and 359.

For example, in the above example, the time count is 36
0-2 = 358.

From the calculated time count and the current time, the time count of the table to be written is obtained by the following formula, and the satellite number or the like currently being tracked is written in that section. If all satellites cannot be acquired, data indicating that reception is not possible is written.

Division of time count to be written = (current GPS time mod 86400) / 240 + time count For example, when the current GPS time is 00:05:00, the time count to be written is (5 * 60) / 240 + 358 =
It becomes 359.

The time count to be written is 0 to 3
Normalize between 59.

In the above example, time count = 3
Write the satellite number and Doppler frequency at section 59.

Reference date for table calculation and 00: 0
Update the time count at 0:00. In the case of the above example, the base date is July 23, 1996, and 00: 0
The time count at 0:00 is updated to 358.

As described above, the data of the table is written, and by repeating this, the tracking information of the past satellite is learned at any time.

The procedure for reading necessary data from the above table is as follows.

G to wake up next time
Calculate date from PS time.

From the difference between the date and the reference date for calculating the table, a time count for advancing by 4 minutes per day is calculated.

Time count = (reference date−date to be woken up) +00: 00: 00 Time count For example, the time count on July 24, 1996 is given assuming that the reference date is July 23, 1996. It becomes -1.

The time count is normalized between 0 and 359.

For example, in the case of the above example, the time count is 36
0-1 = 359.

From the calculated time count and the time at which wake-up is to be performed, the time count of the table to be read is determined by the following equation, and the satellite number and the like of that section are read.

Division of time count to be read = (time to wake up mod86400) / 240 + time count For example, the time to next wake up is 00:
At 15:00, the time count to be read is (1
5 * 60) / 240 + 359 = 362.

The time count to be read is 0 to 3
Normalize between 59.

In the above example, time count = 362-3
The contents at the section of 60 = 2 are read.

As shown in FIG. 10, if data indicating that reception is not possible is written in the corresponding section, it is expected that satellite acquisition will not be possible in that time zone. In this way, the time that goes back to the time zone in which the satellite can be captured is obtained as the next wake-up time Tup. In the example shown in FIG. 10, since the satellite number is written in the section of time count 1 which is four minutes back, the next wake-up time may be set to 00:11:00.

FIG. 11 is a flowchart showing the procedure of an interrupt process according to an interrupt signal generated by the counter 14 every 5 ms. This process is performed regardless of whether the apparatus is in the sleep mode. When this interrupt is activated, the apparatus is started up first (in the full power mode), and the number of interrupts is counted. 1P
When setting the PS correction amount every second, when the number of interrupts reaches 200, the interrupt count is reset and the 1 PPS correction amount is calculated. Simply 1PPS from the clock offset
The correction amount can be obtained, but even during the sleep time,
In order to estimate and cancel the drift caused by the frequency error of the reference clock signal, [clock offset] + [clock drift × elapsed time during sleep time] is set as 1 PPS correction amount. Here [Clock drift]
Is the frequency error of the reference clock signal, and is also the deviation of the clock offset per unit time. Therefore,
Until the position of the receiving point is determined, the deviation of the clock offset per unit time is determined and used. For example, a value obtained by dividing the difference between the clock offset of the previous time (immediately before entering the sleep mode) and the clock offset obtained by the current activation by the sleep time is defined as the clock drift. Further, after the position of the receiving point is determined, it is calculated from the difference between the frequency obtained by observing the transmission signal of each satellite viewed from the receiving point and the calculated frequency. That is, the relative momentum of the satellite viewed from the receiving point is obtained from the orbit information of the satellite and the GPS time, and the Doppler frequency is calculated backward to obtain the Doppler frequency of the calculated received signal. The frequency error of the reference clock signal is determined from the difference between the observed Doppler frequency and the calculated Doppler frequency, and the deviation of the clock offset per unit time is determined therefrom, and this is used as the clock drift. The 1PPS correction amount thus obtained is set in the latch circuit 33 shown in FIG. Thereafter, an interrupt end process is performed. In this process, the mode is returned to the mode at the start of the interrupt process. That is, if the interrupt process is performed in the sleep mode, the process returns to the sleep mode. If the value of the above-mentioned interrupt count has not reached 200, the interrupt end processing is performed as it is. The power required for the interrupt processing every 5 ms is extremely small, and the power required for calculating the 1 PPS correction amount per second and setting the latch circuit is also small.

In the example shown in FIG. 1, a clock circuit is provided separately from the timer of the control circuit for measuring the sleep time. However, the clock circuit may be shared. Further, in the example shown in FIG. 2, 1PPS is generated by using a free-run counter that counts every 6 seconds. However, a free-run counter that counts every 1 second is used, or the comparison circuit uses 6 seconds. If a comparison is made between the digit of the cycle free-run counter of less than one second and the latch circuit, it is not necessary to rewrite the 1PPS correction amount given to the latch circuit every second. It is not necessary to perform the correction, and the clock drift may be corrected in a longer period. That is, if the clock offset is 550 when represented by the value of the free-run counter,
When a new clock offset is obtained, 550 is set in the latch circuit, and thereafter, for example, 1PPS given to the latch circuit according to the clock drift every one minute or every ten minutes
The correction amount may be estimated and rewritten to, for example, 551 or 549. Further, when the correction for the clock drift is not performed at all, it is not necessary to rewrite the 1PPS correction amount given to the latch circuit during the time from obtaining the time by receiving the signal from the satellite until the next reception. The short-time interrupt processing shown in FIG. 11 is also unnecessary.

[0052]

According to the first and seventh aspects of the present invention, a signal including time information transmitted from a positioning satellite is intermittently received, so that the entire average power consumption is suppressed. In addition, since the time content of the time measuring means is intermittently corrected by the time information extracted by receiving the signal from the positioning satellite, it is possible to suppress the power consumption while maintaining the predetermined accuracy.

According to the second and eighth aspects of the present invention, since the signal including the time information transmitted from the positioning satellite is intermittently received, the average power consumption as a whole is suppressed, Further, since the correction of the clock bias and the correction of the drift are performed on the contents of the time measurement, a temporal error from the reception of the signal from the positioning satellite to the next reception is suppressed. As a result, the average timekeeping accuracy is increased without shortening the intermittent reception interval.

According to the third aspect of the present invention, it is possible to measure time or generate a timing signal with required timing accuracy regardless of the accuracy of the reference clock signal.

According to the fourth aspect of the present invention, time information superimposed on a signal transmitted from a positioning satellite can be efficiently received, and power consumption can be suppressed to a minimum. it can.

According to the fifth aspect of the present invention, when the receiving operation is intermittently repeated, the signal from the positioning satellite can be reliably received at the next reception, and the timekeeping content can be corrected. The required accuracy can be maintained without failure.

According to the sixth aspect of the present invention, even if the orbit information of each satellite is unknown, since the same satellite is within the field of view as viewed from the receiving point for each time zone, the satellite was successfully received in the past. Reception possibility determination can be performed depending on the presence or absence of a positioning satellite.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an electronic timepiece according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a counter in FIG.

FIG. 3 is a diagram showing a relationship between timing of satellite search and time calculation and time accuracy, and the like.

FIG. 4 is a diagram showing a configuration of a navigation message included in a signal transmitted from a satellite.

FIG. 5 is a diagram showing the relationship between the system time on the satellite side, the system time on the receiver side, and the time count.

FIG. 6 is a flowchart showing an overall processing procedure of the electronic timepiece.

FIG. 7 is a flowchart showing a procedure for calculating a next wake-up time.

FIG. 8 is a diagram showing the relationship between the required accuracy of timekeeping content and the sleep time.

FIG. 9 is a diagram showing a collection timing of UTC parameters.

FIG. 10 is a diagram illustrating an example of a captured satellite table.

FIG. 11 is a flowchart illustrating a procedure of an interrupt process performed at a constant cycle.

Claims (8)

[Claims] 1. A means for counting a reference clock signal to measure time or generate a timing signal having a fixed period, and intermittently receiving a signal including time information transmitted from a positioning satellite to obtain time information. An electronic timepiece comprising: means for extracting and correcting the clock content of the clock means or the generation timing of the timing signal. 2. A means for counting a reference clock signal to measure time or generate a timing signal having a fixed period, and intermittently receiving a signal including time information transmitted from a positioning satellite, and Means for extracting a clock bias component and a drift component of the clock content by the means, and intermittently correcting the drift component together with the clock bias correction with respect to the clock content or the timing of the timing signal generated by the clock component. Electronic timepiece comprising: 3. The electronic timepiece according to claim 1, wherein the intermittent period is set such that a correction amount of the content of the clock by the clock unit is less than a predetermined value. 4. A means for detecting a timing at which time information is superimposed on a signal transmitted from a positioning satellite, and the intermittent period is set to a timing at which the time information is received at the next reception. The electronic timepiece according to any one of claims 1 to 3, further comprising means for automatically determining the time. 5. A reception possibility determining means for determining a reception possibility of a signal from each positioning satellite in each time zone, and the intermittent period is set so that a signal from the positioning satellite is transmitted at the time of next reception. The electronic timepiece according to any one of claims 1 to 4, further comprising means for automatically determining a time zone in which the time can be received. 6. The reception possibility determination means stores, for each time zone, positioning satellites that have been successfully received in each time zone, and determines whether there is any positioning satellite that has been successfully received in the past in a predetermined time zone. The electronic timepiece according to claim 5, wherein the electronic timepiece is used for determination. 7. Counting a reference clock signal to measure time or generate a timing signal having a fixed period, and intermittently receive a signal including time information transmitted from a positioning satellite to extract time information. And correcting the content of the timing or the timing of generation of the timing signal. 8. Counting a reference clock signal to measure time or generate a fixed period timing signal, intermittently receiving a signal including time information transmitted from a positioning satellite, and performing the time measurement. A clock bias component and a drift component are extracted, and the drift component is intermittently corrected together with the clock bias component with respect to the timing content or the timing signal generation timing. Method.