JP6945473B2 - Satellite radio clock - Google Patents

Description

The present invention relates to a satellite radio clock that receives a satellite signal transmitted from a satellite and corrects an internal time.

A satellite radio-controlled clock that receives a satellite signal transmitted from a satellite and corrects the internal time is known (see, for example, Patent Document 1). Such a satellite radio clock has a receiving circuit that converts the satellite signal received from the satellite into a baseband signal and outputs the decoded time information, and a control circuit that corrects the internal time based on the decoded time information. Have.

Here, among the satellite signals, the data related to the time information is included in the handover word (HOW), the TOW indicating the elapsed time from 0 o'clock on the latest Sunday, the WN indicating the week number, and the current leap second. There is _{a Δt LS} that indicates the offset value of.

In addition, in the satellite signal, in addition to the current leap second offset value Δt _LS , information on the leap second offset value to be updated in the future, specifically, the week number WN _LSF of the week in which the leap second is updated, and the leap The update date DN of the second and the offset value Δt _LSF of the leap second after the update are included.

Based on this information, the control circuit of the satellite radio-controlled clock _{calculates the leap second update timing and the updated leap second offset value Δt LSF} , and when the internal time reaches the update timing (if it has passed), the leap second Update the offset value of.

Here, from the receiving circuit, as the update information of the off-second, _{8-bit data having the current off-second offset value Δt LS} , 8-bit data having the updated off-second offset value Δt _LSF , and off-second An example is 8-bit data that is the WN at the time of update, 10-bit data that adds the upper two digits of the received WN, and 4-bit data that is the update date DN of the quiet seconds, for a total of 28 to 30 bits of data. Is transmitted to the control circuit.

Japanese Unexamined Patent Publication No. 2011-208949

In such a satellite radio-controlled timepiece, a control circuit having a small circuit scale is desired from the viewpoint of reducing power consumption and space saving. Therefore, since the processing capacity of this control circuit is limited to a certain extent, it is desirable that the load on the control circuit can be reduced as much as possible with respect to the above-mentioned leap second update information.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a satellite radio clock that can reduce the burden on a control circuit as much as possible.

In order to achieve the above object, the satellite radio clock of the present invention includes a receiving circuit that receives a satellite signal transmitted from a satellite and outputs time information, and a control circuit that corrects an internal time based on the time information. The control circuit has a week number storage unit in which the week number information included in the time information is stored, and the receiving circuit includes the week number information stored in the week number storage unit and the time information. It is characterized by having a difference data calculation unit that calculates the difference data from a predetermined time to the timing when the leap second is updated based on the information about the leap second and outputs it to the control circuit.

In the satellite radio clock of the present invention configured in this way, the difference data calculation unit of the receiving circuit uses the week number information stored in the week number storage unit of the control circuit and the leap second information included in the time information. Based on this, the difference data from the predetermined time to the timing when the leap second is updated is calculated and output to the control circuit.

Therefore, it is possible to reduce the data transmitted from the receiving circuit to the control circuit for the receiving operation for acquiring the leap second update information (hereinafter referred to as the leap second receiving operation), thereby being based on the data. The burden on the control circuit that performs the leap second reception operation can be reduced as much as possible.

It is a front view which shows the appearance of the satellite radio clock which is embodiment of this invention. It is a block diagram which shows the schematic structure of the satellite radio clock which is an embodiment. It is a sequence diagram which shows an example of the leap second reception operation of the conventional satellite radio clock. It is a sequence diagram which shows another example of the leap second reception operation of the conventional satellite radio-controlled timepiece. It is a sequence diagram which shows an example of the leap second reception operation of the satellite radio clock which is an embodiment. It is a sequence diagram which shows another example of the leap second reception operation of the satellite radio clock which is an embodiment. It is a figure which shows an example of the data used at the time of the leap second reception operation of the satellite radio clock which is a conventional and embodiment. It is a figure which shows the structure of the satellite signal transmitted from the satellite. It is a figure which shows the content of the frame of the satellite signal transmitted from the satellite.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a front view showing the appearance of the satellite radio-controlled clock according to the embodiment of the present invention, and FIG. 2 is a block diagram showing a schematic configuration of the satellite radio-controlled clock according to the embodiment. The satellite radio-controlled clock W according to the present embodiment is an application of the satellite radio-controlled clock of the present invention to a wristwatch, receives a satellite signal including time information transmitted by the satellite, and uses this time information for time information. Make corrections.

As shown in FIG. 1, the satellite radio-controlled clock W according to the present embodiment has a body 1 which is an exterior (clock case) of the satellite radio-controlled clock W, a dial 2 arranged in the body 1, and a pointer indicating a time. It has an hour hand 3, a minute hand 4, and a second hand 5. Further, a crown 6 and a button 7 for the user to perform various operations are arranged on the side surface of the body 1 on the 3 o'clock side. A band fixing portion 8 for fixing the band extends from the side surfaces of the body 1 on the 12 o'clock side and the 6 o'clock side.

The design, pointers, and the like of the satellite radio-controlled clock W shown in FIG. 1 are examples, and the external configuration of the satellite radio-controlled clock W to which the present invention is applied is not limited to FIG. As an example, the body 1 may be square instead of round, and the presence / absence, number, and arrangement of the crown 6 and the button 7 are arbitrary. Further, in the example shown in FIG. 1, the pointers are three, the hour hand 3, the minute hand 4, and the second hand 5, but the present invention is not limited to this, and the second hand 5 may be omitted, or the day of the week, the time zone, or the daylight saving time. You may add a guideline for displaying the presence / absence, the reception status of radio waves, the remaining battery level, various displays, a date display, and the like.

As shown in FIG. 2, the satellite radio clock W according to the present embodiment includes an antenna 10, a receiving circuit 20, a control circuit 30, an oscillator 31, a power supply 40, a drive mechanism 50, and a time display unit 51.

The antenna 10 (see also FIG. 1) receives a satellite signal transmitted from the satellite. In the present embodiment, the antenna 10 receives radio waves having a frequency of about 1.6 GHz transmitted from a GPS (Global Positioning System) satellite. GPS is a kind of satellite positioning system, and is realized by a plurality of GPS satellites orbiting the earth. Each of these GPS satellites is equipped with a high-precision atomic clock, and periodically transmits satellite signals including time information measured by the atomic clock. In the following, the time indicated by the time information included in the satellite signal is referred to as GPS time.

The receiving circuit 20 decodes the satellite signal received by the antenna 10 and outputs the satellite signal obtained as a result of the decoding, particularly a bit string (received data) indicating the content of time information. Specifically, the receiving circuit 20 includes a high frequency circuit (RF circuit) 21, a decoding circuit 22, and a difference data calculation unit 23.

The high-frequency circuit 21 is an integrated circuit that operates at a high frequency, and amplifies and detects an analog signal received by the antenna 10 to convert it into a baseband signal. The decoding circuit 22 is an integrated circuit that performs baseband processing, decodes the baseband signal output by the high frequency circuit 21, generates a bit string indicating the content of the data received from the GPS satellite, and refers to the control circuit 30. Output.

The difference data calculation unit 23 determines a predetermined time based on the week number information stored in the week number (WN) storage unit 34, which will be described later, and the leap second information included in the time information output from the decoding circuit 22. The difference data from to the timing when the leap second is updated is calculated and output to the control circuit 30. Preferably, the difference data has a number of days from a predetermined time to the next leap second update date and a difference number of seconds between the current leap second and the updated leap second.

The control circuit 30 is a microcomputer or the like, and a program stored in a storage medium such as a ROM (Read Only Memory) or a RAM (Random Access Memory) (not shown) is also executed by a calculation unit (not shown). Then, various information processing operations are performed according to this program. In addition, data to be processed during various information processing operations is also temporarily stored in the above-mentioned storage medium.

The control circuit 30 has an internal time generation unit 32, a week number (WN) count unit 33, a week number (WN) storage unit 34, and a leap second update unit 35.

The oscillator 31 supplies a clock signal used for timing inside the satellite radio clock W, and the internal time generator 32 receives the internal time measured by the signal supplied from the oscillator 31 by the receiving circuit 20. The time (display time) to be displayed on the time display unit 51 is determined by making corrections based on the time information. Then, the control circuit 30 outputs a drive signal for driving the motor included in the drive mechanism 50, which will be described later, according to the determined display time. As a result, the display time generated by the control circuit 30 is displayed on the time display unit 51.

Every time the week number counting unit 33 receives the week number (WN) information from the receiving circuit 20, the week number information stored in the week number storage unit 34 is updated, and the internal time generating unit 32 sets the week number to 0 on Sunday. Every time the hour 00:00 is counted, the week number information stored in the week number storage unit 34 is updated. In this way, the week number storage unit 34 always stores the updated week number information.

The week number information stored in the week number storage unit 34 is appropriately transmitted to the receiving circuit 20 when the satellite signal is received by the receiving circuit 20.

Further, when the week number information exceeds a certain value (1023 weeks = about 19.6 years), it becomes a rollover (overflow) and is reset to 0. Therefore, the week number storage unit 34 has a rollover count unit (not shown) having a capacity of about 5 bits, and the rollover count unit stores the number of times the week number information is reset. The information of the rollover count unit is also appropriately transmitted to the receiving circuit 20 when the satellite signal is received by the receiving circuit 20. Since the week number information takes a value from 0 to 1023, it suffices to have a capacity of 10 bits.

The power source 40 includes a power storage device such as a secondary battery, and stores the electric power generated by the solar cell (not shown). Then, the stored electric power is supplied to the receiving circuit 20 and the control circuit 30. In particular, a switch 41 is provided in the middle of the power supply path from the power supply 40 to the receiving circuit 20, and the on / off of the switch 41 is switched by the control signal output from the control circuit 30. That is, the control circuit 30 can control the operation timing of the reception circuit 20 by switching the switch 41 on / off. The receiving circuit 20 operates only while power is being supplied from the power source 40 via the switch 41, and decodes the satellite signal received by the antenna 10 during that time.

The solar cell is arranged under the dial 2 (see FIG. 1), generates electricity by external light such as sunlight radiated to the satellite radio clock W, and supplies the generated electric power to the power source 40.

The drive mechanism 50 includes a step motor that operates in response to a drive signal output from the control circuit 30, and a train wheel. The wheel train transmits the rotation of the step motor to provide a pointer (hour hand 3). , Minute hand 4, second hand 5) is rotated.
The details of the operations of the difference data calculation unit 23, the week number counting unit 33, and the week number storage unit 34 constituting the receiving circuit 20 and the control circuit 30 will be described later.

Next, the configuration of the satellite signal transmitted by the GPS satellite will be described. 8 and 9 are schematic views showing the configuration of satellite signals (navigation data) transmitted from GPS satellites. As shown in FIG. 8, each GPS satellite repeatedly transmits navigation data with a total of 25 frames (pages) as one set. Each frame contains a signal for 30 seconds, and the GPS satellite transmits a signal of all 25 frames in a cycle of 12.5 minutes. Further, each frame is composed of 5 subframes. Since one frame is 30 seconds, one subframe corresponds to a signal for 6 seconds. Further, one subframe is composed of 10 words, and one word contains 30 bits of information, and one subframe contains 300 bits of information in total. Here, the fourth subframe and the fifth subframe have different contents for each transmitted frame, and each is composed of 25 pages. Information about leap seconds is contained in the fourth subframe of the frame on page 18.

As shown in FIGS. 8 and 9 (a), the first word (first word) of each subframe is called a TLM (TeLeMetry word), and the first portion thereof (that is, the first portion of the entire subframe) is included. , A preamble indicating the start position of the subframe is included. Further, the second word (second word) of each subframe is called HOW (HandOver Word), and the head portion thereof contains time information called TOW (Time Of Week). This TOW is time information indicating the GPS time starting from the beginning of the week (0:00 am on Sunday). By receiving the TOW data from one or more GPS satellites and combining it with the information of the week number WN, the satellite radio clock W can know the GPS time measured by the GPS satellites. The week number WN is information indicating the number of the week to which the time represented by TOW belongs, and is counted up once a week at 0:00 am on Sunday. The information of the week number WN is stored in the first subframe of each frame and transmitted from the GPS satellite.

The satellite radio clock W can acquire the time information transmitted by the GPS satellite by receiving the TOW included in any of the subframes. However, the GPS time indicated by this time information has a deviation of an integer second caused by leap seconds with respect to Coordinated Universal Time (UTC). Specifically, the GPS time deviates from Coordinated Universal Time by the amount of leap seconds accumulated since the time of the first launch of the GPS satellite (1980). Therefore, the satellite radio-controlled clock W needs to correct the GPS time obtained from the GPS satellite to a time compliant with the agreement world time using leap second information.

Information on leap seconds required for this correction is also periodically transmitted from GPS satellites. Specifically, as shown in FIG. 9B, out of all 25 frames of satellite signals transmitted by GPS satellites, the fourth subframe of the frame on the 18th page contains information on leap seconds. .. Specifically, the offset value Δt of the current leap second, which is an integer value to be corrected with respect to the leap second adjustment for the leap second adjustment in the latter two words of this subframe (that is, after 241 bits counting from the beginning). Contains information about _LS.

In addition, the subframe including the current leap second offset value Δt _LS includes the current leap second offset value Δt _LS and information on the scheduled date and time when the next leap second adjustment is performed (leap second adjustment notice information). It has been. _{Specifically, the week number WN LSF} of the week in which the leap second is updated, the update date DN of the leap second, and the offset value Δt _LSF of the leap second after the update are included. This information is updated when the scheduled date for the next leap second adjustment is determined, and while the timing for the next leap second adjustment has not yet been determined, information indicating the date and time when the previous leap second adjustment was performed. It has become. If this leap second adjustment notice information indicates a future date and time, it can be seen that _{the offset value Δt LS of the current leap second is not changed until the date and time arrives.}

Hereinafter, in the present specification, the current leap second offset value Δt _{LS , the week number WN LSF} of the week in which the leap second is updated, the leap second update date DN, and the updated leap second offset value Δt _LSF are used. Collectively referred to as leap second information.

Since the leap second information is included in only one subframe of all navigation data, it is transmitted from the GPS satellite once every 12.5 minutes.

Further, it is necessary to consider the time difference between the internal time generated by the internal time generation unit 32 and the agreed world time. The time difference is obtained by positioning reception using satellite signals transmitted from GPS satellites, or is calculated based on a city name or the like manually set by the user using a button 7 or the like.

Next, before explaining the leap second reception operation by the satellite radio-controlled clock W according to the present embodiment, a general satellite including the conventional satellite radio-controlled clock described above is referred to with reference to the sequence diagrams of FIGS. 3 and 4. The leap second reception operation of the radio-controlled clock will be described.

FIG. 3 is a sequence diagram showing an example of a leap second reception operation of a general satellite radio-controlled clock.

First, in step S1, the control circuit 30 issues a command to activate the receiving circuit 20 by turning on the switch 41 at predetermined intervals. In step S2, when the switch 41 is turned on in step S1, power is supplied to the receiving circuit 20 and the receiving circuit 20 is turned on. When the receiving circuit 20 is turned on, the receiving circuit 20 receives the satellite signal from the antenna 10, and the high frequency circuit 21 and the decoding circuit 22 generate time information.

Then, as shown in step S3, the receiving circuit 20 acquires leap second information over a maximum of 12.5 minutes as described above. The time from when the power of the receiving circuit 20 is turned on until the receiving circuit 20 acquires the leap second information differs depending on the timing when the receiving circuit 20 receives the fourth subframe of the frame on the 18th page.

The receiving circuit 20 that has acquired the leap second information sends the time information including the leap second information to the control circuit 30 in step S4. At this time, the data transmitted from the receiving circuit 20 to the control circuit 30 has the leap second information shown in FIG. 7A, that is, the current leap second offset value Δt _LS is 8 bits, and the updated leap second offset. The value Δt _{LSF is 8 bits, the week number WN LSF} of the week in which the leap second is updated is 8 bits, and the update date DN of the leap second is 4 bits, for a total of 28 bits, and HOW data as time information is included. Here, since the WN _LSF is 8-bit, the correct week number of the week in which the leap second is updated is unknown. The control circuit 30 can calculate the correct week number of the week in which the leap second is updated by adding the upper two bits of the week number WN stored inside the clock before the 8-bit data of _{the WN LSF.} ..

After that, in step S5, the control circuit 30 issues a command to stop the activation of the receiving circuit 20 by turning off the switch 41, and when the switch 41 is turned off in step S5, the receiving circuit 20 is reached in step S6. The power supply is cut off and the receiving circuit 20 is turned off.

Next, FIG. 4 is a sequence diagram showing another example of the leap second reception operation of a general satellite radio-controlled clock.

In the example shown in FIG. 4, first, in step S10, the control circuit 30 issues a command to turn on the receiving circuit 20 at predetermined intervals, and in step S11, the receiving circuit 20 is turned on based on this command.

When the receiving circuit 20 receives the satellite signal from the antenna 10, the receiving circuit 20 acquires the HOW in a maximum of 6 seconds as shown in step S12, and then the receiving circuit 20 acquires a HOW in a maximum of 30 seconds as shown in step S13. In the meantime, the receiving circuit 20 acquires the week number (WN), and as shown in step S14, the receiving circuit 20 acquires the leap second information in a maximum of 12.5 minutes. In the example shown in FIG. 4, since the week number WN is acquired, the correct week number of the week in which the leap second is updated is set to 8 bits of _{the week number WN LSF of the week in which the upper 2 bits of the week number WN are updated.} By adding it, it can be calculated on the receiving circuit side.

The receiving circuit 20 that has acquired the leap second information sends the time information including the leap second information to the control circuit 30 in step S15. At this time, the data transmitted from the receiving circuit 20 to the control circuit 30 is leap second information (30) including _{the week number WN LSF} of the week to which the upper two bits of the week number (received WN) shown in FIG. 7B are added. Bit), the week number (received WN) acquired in step S13, and HOW data.

After that, in step S16, the control circuit 30 issues a command to stop the activation of the receiving circuit 20 by turning off the switch 41, and when the switch 41 is turned off in step S16, the receiving circuit 20 is reached in step S17. The power supply is cut off and the receiving circuit 20 is turned off.

As described above, in a general satellite radio-controlled clock, 30-bit data is transmitted from the receiving circuit 20 to the control circuit 30 as leap second information. The satellite radio-controlled clock W according to the present embodiment is provided with a week number storage unit 34 in the control circuit 30, and provides the week number (WN) information stored in the week number storage unit 34 to the reception circuit 20. , The number of bits of leap second information transmitted from the receiving circuit 20 to the control circuit 30 is reduced.

As described above, the receiving circuit 20 generates time information based on the satellite signal from the antenna 10, but does not retain this time information. On the other hand, since the control circuit 30 generates a substantially accurate internal time in the internal time generation unit 32, the week number (WN) information stored in the week number storage unit 34 is also substantially accurate.

Then, by sharing the week number (WN) information stored in the week number storage unit 34 between the receiving circuit 20 and the control circuit 30, all the leap second information obtained from the satellite signal is transmitted from the receiving circuit 20 to the control circuit. By transmitting the difference value without transmitting to 30, the number of bits of the leap second information to be transmitted is reduced.

FIG. 5 is a sequence diagram showing an example of the leap second reception operation of the satellite radio clock W according to the present embodiment.

In the example shown in FIG. 5, first, in step S20, the control circuit 30 issues a command to turn on the receiving circuit 20 at predetermined intervals, and in step S21, the receiving circuit 20 is turned on based on this command.

Here, in the satellite radio clock W according to the present embodiment, in step S20, the control circuit 30 issues a command to turn on the reception circuit 20, and the roll stored in the rollover count unit of the week number storage unit 34. Over information (also week number information) is being sent.

When the receiving circuit 20 receives the satellite signal from the antenna 10, the receiving circuit 20 acquires the HOW in a maximum of 6 seconds as shown in step S22, and then the receiving circuit 20 acquires a HOW in a maximum of 30 seconds as shown in step S23. In the meantime, the receiving circuit 20 acquires the week number (WN), and as shown in step S24, the receiving circuit 20 acquires the leap second information in a maximum of 12.5 minutes.

In step S25, the difference data calculation unit 23 of the receiving circuit 20 that has acquired the time information including the leap second information and further received the rollover information from the control circuit 30 uses the time information and the rollover information. Calculate the difference data from the current time to the timing when the leap second is updated. Here, the difference data, as shown in FIG. 7 (c), and 8-bit data as the offset value Delta] t _LS current leap second, from the offset value Delta] t _LS current leap seconds at the next leap second update 1 It is 1-bit data indicating whether to advance by seconds (+) or delay by 1 second (-), and data indicating the number of days until the next leap second update date.

The number of bits of the data indicating the number of days until the next leap second update date differs depending on which time point is used as the starting point, but in the example shown in FIG. 7 (c), the maximum number of days is half a year. The number of bits of is 8 bits. Since the leap second update timing is usually at least half a year, if the maximum number of half a year's worth of days is secured as data indicating the number of days until the next leap second update date, the control circuit 30 will have no problem at the correct timing. Leap seconds can be updated. At this time, the control circuit 30 may be configured to perform automatic reception control so that leap second information can be acquired every six months. For example, correct information can always be obtained by automatically performing a leap second reception operation between February and June or between August and December. During January and July, it may not be decided whether the next leap second will be inserted, or even if it is decided, it may not be reflected in the satellite signal, so the leap second reception operation will not be performed during that time. It is good to do so.

If the number of days until the next leap second update date has already passed, it can be indicated that the update date has passed by setting the data related to this number of days to 0. Further, by setting the data related to the number of days to 0, it can be shown that the leap second is not inserted on January 1st or July 1st, which is usually the leap second update date.

From the above, the difference data calculated by the difference data calculation unit 23 is 17-bit data.

The receiving circuit 20 that has calculated the difference data sends the time information including the difference data to the control circuit 30 in step S26. At this time, the data transmitted from the receiving circuit 20 to the control circuit 30 is the difference data (17 bits) shown in FIG. 7C, the week number (received WN) acquired in step S23, and the data acquired in step S22. Includes HOW data.

After that, in step S27, the control circuit 30 issues a command to stop the activation of the receiving circuit 20 by turning off the switch 41, and when the switch 41 is turned off in step S27, the receiving circuit 20 is reached in step S28. The power supply is cut off and the receiving circuit 20 is turned off.

In the control circuit 30 that has received the difference data, the leap second update unit 35 updates the leap second based on the difference data.

The method of updating the leap second by the leap second updating unit 35 is arbitrary, but as an example, first, the leap second updating unit 35 _{stores the current leap second offset value Δt LS} in the storage medium in the control circuit 30. Next, the leap second update unit 35 is updated based on the current leap second offset value Δt _LS and data indicating whether to advance by 1 second (+) or delay by 1 second at the next leap second update (-). The leap second offset value Δt _LSF is calculated and also stored in the storage medium in the control circuit 30.

Further, when the leap second update unit 35 determines whether or not the number of days until the next leap second update date is 0 and determines that the number of days is not 0 (that is, takes a positive value), the data regarding the number of days and the data regarding the number of days are determined. Based on the internal time generated by the internal time generation unit 32 or the time information received from the reception circuit 20, the week number WN _LSF of the week in which the leap second is updated and the update date DN of the leap second are generated.

On the other hand, when the leap second update unit 35 determines that the data related to the number of days is 0, the leap second update date DN is cleared, and this update date DN does not exist, that is, a non-existent day (February 30 as an example). , November 31st, etc.).

Then, when the internal time generated by the internal time generation unit 32 and the update date DN match, or when the update date DN has passed, the leap second update unit 35 sets the updated leap second offset value Δt _LSF to the time. To reflect.

Next, FIG. 6 is a sequence diagram showing another example of the leap second reception operation of the satellite radio clock W according to the present embodiment.

In the example shown in FIG. 6, first, in step S31, the control circuit 30 refers to the internal time generated by the internal time generation unit 32, and the leap second information is included in the satellite signal received by the antenna 10. The timing, in other words, waiting immediately before receiving the fourth subframe of the frame on the 18th page, then, in step S31, the control circuit 30 issues a command to turn on the receiving circuit 20, and in step S32, the receiving circuit 20 issues a command to turn on the receiving circuit 20. It is turned on based on this command.

Here, in the satellite radio-controlled clock W according to the present embodiment, in step S31, the control circuit 30 issues a command to turn on the receiving circuit 20, and the week number information (including rolls) stored in the week number storage unit 34. The rollover information stored in the overcount section) is being transmitted.

When the receiving circuit 20 receives the satellite signal from the antenna 10, the receiving circuit 20 acquires the HOW and leap second information within a maximum of 6 seconds as shown in step S33.

In step S34, the difference data calculation unit 23 of the receiving circuit 20 that has acquired the time information including the leap second information and further received the week number information from the control circuit 30 uses the time information and the week number information to make a difference. Calculate the data. Since the procedure for calculating the difference data in step S34 is the same as that in step S25 described above, the description here will be omitted.

The receiving circuit 20 that has calculated the difference data sends the time information including the difference data to the control circuit 30 in step S35. At this time, the data transmitted from the receiving circuit 20 to the control circuit 30 includes the difference data (17 bits) shown in FIG. 7C and the HOW data acquired in step S33.

After that, in step S36, the control circuit 30 issues a command to stop the activation of the receiving circuit 20 by turning off the switch 41, and when the switch 41 is turned off in step S36, the receiving circuit 20 is reached in step S37. The power supply is cut off and the receiving circuit 20 is turned off.

In the control circuit 30 that has received the difference data, the leap second update unit 35 updates the leap second based on the difference data. Since the leap second update procedure by the leap second update unit 35 is the same as that described above, the description here will be omitted.

Note that the operations in steps S31 and S32 in FIG. 6 correspond to an activation control unit that activates the reception circuit 20 at the timing when the reception circuit 20 receives information on leap seconds.

In the satellite radio-controlled clock W of the present embodiment configured as described above, the difference data calculation unit 23 of the receiving circuit 20 has the week number information and the time information stored in the week number storage unit 34 of the control circuit 30. Based on the information about the leap second included in the above, the difference data from the predetermined time to the timing when the leap second is updated is calculated and output to the control circuit 30.

Therefore, the data transmitted from the receiving circuit 20 to the control circuit 30 for the leap second receiving operation can be reduced, and as a result, the burden on the control circuit 30 that performs the leap second receiving operation based on the data can be reduced as much as possible. Can be reduced.

That is, as shown in FIG. 7B, in a general satellite radio-controlled timepiece, 30-bit data is transmitted from the receiving circuit 20 to the control circuit 30 as leap second information, but this is the embodiment. According to the satellite radio clock W, as shown in FIG. 7 (c), this can be reduced to 17-bit data. As a result, the burden on the leap second update unit 35 based on the reduced data can be reduced as much as possible.

In the satellite radio clock W of the present embodiment, the difference data calculation operation is performed by the receiving circuit 20, but since the receiving circuit 20 is usually more sophisticated than the control circuit 30, the receiving circuit 20 is used. There is no big problem in causing the difference data calculation unit 23 to perform the difference data calculation operation.

In particular, in the operation example shown in the sequence diagram of FIG. 6, since the WN and rollover data stored inside the clock are used, it is not necessary to acquire WN information by reception, and the timing when the leap second information is included in the satellite signal is determined. Waiting until just before, the control circuit 30 turns on the power of the receiving circuit 20 and performs the receiving operation. As a result, the time during which the receiving circuit 20 is on can be shortened as compared with other embodiments, and the power consumption of the entire satellite radio clock W can be reduced. Further, by shortening the reception time, the reception performance can be improved because it is less affected by changes in the surrounding environment during reception than in other embodiments.

Although the embodiments of the present invention have been described in detail with reference to the drawings, the specific configuration is not limited to the embodiments and the examples, and the design changes to the extent that the gist of the present invention is not deviated. Is included in the present invention.

As an example, the difference data transmitted from the receiving circuit 20 to the control circuit 30 is not limited to the above-described embodiment. For example, as shown in FIG. 7D, if the data indicating the number of days until the next bit second update date is for one month, that is, the data taking a value from 0 to 31, until the next bit second update date. The amount of data indicating the number of days can be reduced to 5 bits, and as a result, the amount of difference data can be reduced to 14 bits as a whole.

Although the reception time has been described as having a maximum of 6 seconds, the reception time is not limited to this and may be set to any time. For example, in consideration of the start-up time of the reception circuit 20 and the time required to capture the satellite, the start timing is set so that the preamble of the subframe 4 on page 18 can be acquired, and reception is performed for 6 seconds or more. You may do so.

When receiving satellite radio waves, it is easily affected by the reception environment, and reception may fail in an environment where buildings are crowded indoors or around. Therefore, before starting reception, it may be determined whether or not the reception environment is ready, and if the reception environment is ready, reception may be started. For example, the strength of the received signal, the number of satellites that can be captured, the illuminance, the acceleration of the clock, and the like are measured, and a judgment is made according to each value. If it is determined that the reception environment is not suitable, the leap second data may be acquired at the next reception timing after waiting for 12.5 minutes.

W Satellite radio clock 10 Antenna 20 Reception circuit 21 High frequency circuit 22 Decoding circuit 23 Difference data calculation unit 30 Control circuit 31 Oscillator 32 Internal time generation unit 33 Week number count unit 34 Week number storage unit 35 Leap second update unit

Claims (6)

A receiving circuit that receives satellite signals transmitted from satellites and outputs time information,
In a satellite radio-controlled clock having a control circuit that corrects an internal time based on the time information.
The control circuit has a week number storage unit that stores week number information included in the time information.
The receiving circuit is a difference between a predetermined time and a timing at which the leap second is updated, based on the week number information stored in the week number storage unit and the information regarding the leap second included in the time information. A satellite radio clock characterized by having a difference data calculation unit that calculates data and outputs it to the control circuit. The difference data according to claim 1, wherein the difference data has a number of days from the predetermined time to the next leap second update date and a difference number of seconds between the current leap second and the updated leap second. Satellite radio clock. The satellite radio-controlled clock according to claim 1 or 2, wherein the control circuit includes an activation control unit that activates the reception circuit at a timing when the reception circuit receives information on the leap second. The satellite radio-controlled clock according to any one of claims 1 to 3, wherein the control circuit has a week number counting unit that updates the week number information stored in the week number storage unit. The receiving circuit outputs the week number information as the time information, and outputs the week number information.
The satellite radio wave according to claim 4, wherein the week number counting unit updates the week number information stored in the week number storage unit by using the week number information output from the receiving circuit. clock. The week number information is reset when it exceeds the specified value.
The satellite radio-controlled clock according to any one of claims 1 to 5, wherein the week number storage unit has a rollover count unit for storing the number of resets of the week number information.

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