JP2019148520A - Satellite radio clock - Google Patents

Abstract

To provide a satellite radio clock capable of reducing load on a control circuit as much as possible.SOLUTION: A satellite radio clock W includes a reception circuit 20 that receives a satellite signal transmitted from a satellite and outputs time information, and a control circuit 30 that corrects an internal time on the basis of the time information. The control circuit 30 has a week number storage unit 34 into which week number information included in the time information is stored. The reception circuit 20 has a difference data calculation unit 23 that calculates difference data on a difference from a predetermined time to a timing when a leap second is updated on the basis of the week number information stored in the week number storage unit 34 and information on the leap second included in the time information, and outputs the difference data to the control circuit 30.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a satellite timepiece that receives a satellite signal transmitted from a satellite and corrects the internal time.

  A satellite timepiece 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 timepiece includes a receiving circuit that converts a satellite signal received from a satellite into a baseband signal and outputs decoded time information, and a control circuit that performs a correction process on the internal time based on the decoded time information. Have.

Here, the data related to the time information among the satellite signals is included in the handover word (HOW), TOW indicating the elapsed time from 0:00 on the last Sunday, WN indicating the week number, and the current leap second There is Δt _LS indicating the offset value.

In addition to the current leap second offset value Δt _LS , the satellite signal includes 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, The second update date DN and the updated leap second offset value Δt _LSF are included.

Based on this information, the satellite radio time signal control circuit calculates the leap second update timing and the leap second offset value Δt _LSF after the update, and if 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 leap second update information, the current leap second offset value Δt _LS is 8-bit data, the updated leap second offset value Δt _LSF is 8-bit data, leap second An example is 8-bit data that is the WN at the time of update or 10-bit data to which the upper 2 digits of the received WN are added, and 4-bit data that is the leap second update date DN, totaling 28 to 30 bits. To the control circuit.

JP 2011-208949 A

  In such a satellite radio timepiece, a control circuit having a small circuit scale is desired from the viewpoint of reducing power consumption and saving space. Accordingly, since the processing capability of the control circuit is limited, it is desirable that the load on the control circuit can be reduced as much as possible with the leap second update information described above.

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

  To achieve the above object, a satellite radio timepiece according to 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 reception circuit is included in the week number information stored in the week number storage unit and the time information. It has a difference data calculation unit that calculates difference data from a predetermined time to a timing at which leap seconds are updated based on information on leap seconds and outputs the difference data to a control circuit.

  In the satellite radio timepiece of the present invention configured as described above, the difference data calculation unit of the reception circuit includes the week number information stored in the week number storage unit of the control circuit and the information related to leap seconds included in the time information. Based on this, the difference data from the predetermined time to the timing at which 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 leap second update information (hereinafter referred to as leap second receiving operation). Thus, 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 external appearance of the satellite radio timepiece which is embodiment of this invention. It is a block diagram which shows schematic structure of the satellite radio timepiece which is embodiment. It is a sequence diagram which shows an example of the leap second reception operation | movement of the conventional satellite radio timepiece. It is a sequence diagram which shows the other example of the leap second reception operation | movement of the conventional satellite radio timepiece. It is a sequence diagram which shows an example of the leap second reception operation | movement of the satellite radio timepiece which is embodiment. It is a sequence diagram which shows the other example of the leap second reception operation | movement of the satellite radio timepiece which is embodiment. It is a figure which shows an example of the data used in the case of the leap second reception operation | movement of the satellite radio timepiece which is the past and embodiment. It is a figure which shows the structure of the satellite signal transmitted from a satellite. It is a figure which shows the content of the frame of the satellite signal transmitted from a satellite.

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

  As shown in FIG. 1, a satellite radio timepiece W according to the present embodiment includes a case 1 that is an exterior (watch case) of the satellite radio timepiece W, a dial 2 arranged in the case 1, and a pointer that indicates time. And the hour hand 3, the minute hand 4, and the second hand 5. Further, a crown 6 and buttons 7 for a user to perform various operations are disposed on the side surface of the trunk 1 on the 3 o'clock side. A band fixing portion 8 for fixing the band extends from the side surface of the trunk 1 on the 12 o'clock side and the 6 o'clock side.

  1 is merely an example, and the external configuration of the satellite radio clock W to which the present invention is applied is not limited to FIG. As an example, the body 1 may be a square shape instead of a round shape, and the presence, number, and arrangement of the crown 6 and the button 7 are arbitrary. Further, in the example shown in FIG. 1, the hands are three hands, that is, the hour hand 3, the minute hand 4, and the second hand 5. However, the present invention is not limited to this. Presence / absence, reception state of radio waves, remaining battery level, pointers for various displays, date display, and the like may be added.

  As shown in FIG. 2, the satellite radio timepiece 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 driving mechanism 50, and a time display unit 51.

  The antenna 10 (see also FIG. 1) receives a satellite signal transmitted from a satellite. In the present embodiment, antenna 10 receives a radio wave 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 around the earth. Each of these GPS satellites is equipped with a high-accuracy atomic clock, and periodically transmits a satellite signal including time information measured by the atomic clock. Hereinafter, 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 a satellite signal obtained as a result of the decoding, in particular, a bit string (received data) indicating the contents 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 decode circuit 22 is an integrated circuit that performs baseband processing, decodes the baseband signal output from the high-frequency circuit 21, generates a bit string indicating the content of data received from a GPS satellite, and outputs the bit string to the control circuit 30. Output.

  The difference data calculation unit 23 generates a predetermined time based on week number information stored in a week number (WN) storage unit 34, which will be described later, and information on leap seconds included in the time information that is output from the decoding circuit 22. Difference data from when the leap second is updated to the timing at which the leap second is updated is calculated and output to the control circuit 30. Preferably, the difference data includes the number of days from a predetermined time to the next leap second update date, and the difference in 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) and a RAM (Random Access Memory) not shown is also executed by a calculation unit not shown. Thus, various information processing operations according to this program are performed. In addition, data to be processed during various information processing operations is also temporarily stored in the above-described storage medium.

  The control circuit 30 includes 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 in the satellite radio timepiece W, and the internal time generation unit 32 receives the internal time measured by the signal supplied from the oscillator 31 by the receiving circuit 20. The time to be displayed on the time display unit 51 (display time) is determined based on the corrected time information. Then, the control circuit 30 outputs a drive signal for driving a motor included in the drive mechanism 50 described later in accordance with the determined display time. As a result, the display time generated by the control circuit 30 is displayed on the time display unit 51.

  Each time the week number counting unit 33 receives week number (WN) information from the receiving circuit 20, the week number counting unit 33 updates the week number information stored in the week number storage unit 34, and the internal time generation unit 32 sets the 0 of Sunday. Each time when 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 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 receiving circuit 20 receives the satellite signal.

  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 zero. For this reason, the week number storage unit 34 has an unillustrated rollover count unit having a capacity of about 5 bits, and the number of resets of the week number information is stored in this rollover count unit. Information of the rollover count unit is also transmitted to the receiving circuit 20 as appropriate when the receiving circuit 20 receives the satellite signal. Since the week number information takes a value from 0 to 1023, a 10-bit capacity is sufficient.

  The power source 40 is configured to include a power storage device such as a secondary battery, and stores power generated by a solar cell (not shown). Then, the accumulated 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 a control signal output from the control circuit 30. That is, the control circuit 30 can control the operation timing of the receiving circuit 20 by switching the switch 41 on and off. The receiving circuit 20 operates only while power is supplied from the power supply 40 via the switch 41, and decodes the satellite signal received by the antenna 10 during that time.

  The solar cell is disposed under the dial 2 (see FIG. 1), generates power using external light such as sunlight irradiated on the satellite radio timepiece W, and supplies the generated power to the power source 40.

The drive mechanism 50 is configured to include a step motor that operates in accordance with a drive signal output from the control circuit 30 and a train wheel, and the train wheel transmits the rotation of the step motor so that the pointer (hour hand 3 , The minute hand 4 and the second hand 5) are 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 reception 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 diagrams showing the configuration of satellite signals (navigation data) transmitted from GPS satellites. As shown in FIG. 8, each GPS satellite repeatedly transmits navigation data having a total of 25 frames (pages) as one set. Each frame includes a signal for 30 seconds, and the GPS satellite transmits a signal of 25 frames in a cycle of 12.5 minutes. Further, each frame is composed of five 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, and one subframe includes information for 300 bits. Here, the fourth subframe and the fifth subframe have different contents for each frame to be transmitted, and each is composed of 25 pages. Information on leap seconds is included in the fourth subframe of the frame on the 18th page.

  As shown in FIG. 8 and FIG. 9A, the head word (first word) of each subframe is called a TLM (TeLeMetry word), and the head portion thereof (that is, the head portion of the entire subframe) , 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 includes time information called TOW (Time Of Week). This TOW is time information indicating GPS time starting from the beginning of the week (Sunday 0:00 am). The satellite timepiece W can receive the TOW data from one or a plurality of GPS satellites and combine it with the information of the week number WN to 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 every week at 0:00 am on Sunday. Information of the week number WN is stored in the first subframe of each frame and transmitted from a GPS satellite.

  The satellite timepiece 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 difference of integer seconds caused by leap seconds with respect to Coordinated Universal Time (UTC). Specifically, the GPS time is offset from Coordinated Universal Time by the leap second accumulated since the first launch of the GPS satellite (1980). Therefore, the satellite radio-controlled timepiece W needs to correct the GPS time obtained from the GPS satellite to a time based on Coordinated Universal Time using leap second information.

Information on leap seconds necessary 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 the GPS satellite, information on leap seconds is included in the fourth subframe of the frame on the 18th page. . Specifically, the current leap second offset value Δt, which is an integer value to be corrected with respect to the GPS time for the leap second adjustment in the latter two words of this subframe (that is, 241 bits after the first) Information about _LS is included.

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 advance notice information). It is. Specifically, 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 included. This information is updated when the next leap second adjustment scheduled execution date is determined, and information indicating the date and time when the previous leap second adjustment was performed while the next leap second adjustment execution timing has not yet been determined. It has become. If the leap second adjustment notice information indicates a future date and time, it can be seen that the current leap second offset value Δt _LS is not changed until the date and time arrives.

Hereinafter, in this 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 Collectively called leap second information.

  Since leap second information is included in only one subframe of the entire navigation data, the leap second information is transmitted from the GPS satellite at a cycle of 12.5 minutes.

  In addition, the internal time generated by the internal time generation unit 32 needs to consider a time difference with respect to this coordinated universal time. The time difference is obtained by positioning reception using a satellite signal transmitted from a GPS satellite, or is calculated based on a city name manually set by the user using the button 7 or the like.

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

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

  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, power is supplied to the receiving circuit 20 by turning on the switch 41 in step S1, and the receiving circuit 20 is turned on. When the receiving circuit 20 is turned on, the receiving circuit 20 receives a 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 leap second information varies depending on the timing at which 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 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 includes 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, the leap second update date DN is 4 bits, a total of 28 bits, and HOW data as time information. Here, since WN _LSF is 8 bits, 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 2 bits of the week number WN stored inside the watch before the 8-bit data of WN _LSF. .

  Thereafter, in step S5, the control circuit 30 issues a command to stop activation of the receiving circuit 20 by turning off the switch 41. When the switch 41 is turned off in step S5, the control circuit 30 sends the instruction to the receiving circuit 20 in step S6. And the receiving circuit 20 is turned off.

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

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

When the receiving circuit 20 receives the satellite signal from the antenna 10, as shown in step S12, the receiving circuit 20 acquires HOW during a maximum of 6 seconds, and then, as shown in step S13, a maximum of 30 seconds. In the meantime, the receiving circuit 20 acquires the week number (WN), and as shown in step S14, the receiving circuit 20 acquires leap second information for 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 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 can be calculated on the receiving circuit side.

The receiving circuit 20 that has acquired the leap second information transmits 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 includes leap second information (30) including the week number WN _LSF of the week to which the upper 2 bits of the week number (received WN) shown in FIG. Bit), a week number (received WN) acquired in step S13, and HOW data.

  Thereafter, in step S16, the control circuit 30 issues a command to stop activation of the receiving circuit 20 by turning off the switch 41. When the switch 41 is turned off in step S16, the control circuit 30 sends the instruction to the receiving circuit 20 in step S17. And the receiving circuit 20 is turned off.

  Thus, in a general satellite radio timepiece, 30-bit data is transmitted from the receiving circuit 20 to the control circuit 30 as leap second information. The satellite radio wave clock W according to the present embodiment includes a week number storage unit 34 in the control circuit 30 and provides the reception circuit 20 with week number (WN) information stored in the week number storage unit 34. 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 hold the 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. The number of bits of leap second information to be transmitted is reduced by transmitting the difference value without transmitting to 30.

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

  Also 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-controlled timepiece W according to the present embodiment, in step S20, the control circuit 30 issues a command to turn on the receiving circuit 20, and the roll stored in the rollover count unit of the week number storage unit 34. Over information (this is also week number information) is transmitted.

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

The receiving circuit 20 that acquires time information including leap second information and further receives rollover information from the control circuit 30, the difference data calculation unit 23 uses the time information and rollover information in step S25, Difference data from the current time to the timing when the leap second is updated is calculated. 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 1-bit data indicating whether the second is advanced (+) or delayed by 1 second (−), and data indicating the number of days until the next leap second update date.

  The data indicating the number of days until the next leap second update date is different in the number of bits depending on which time point is used as the starting point. However, in the example shown in FIG. The number of bits is 8 bits. Since the leap second update timing is normally the shortest half year, the control circuit 30 can accurately and accurately control the number of days until the next leap second update date if the number of days for the maximum half year is secured. You can update leap seconds. 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 is always obtained by automatically performing leap second reception operation between February and June or between August and December. In January and July, whether the next leap second will be inserted or not is determined, or even if it is determined, it may not be reflected in the satellite signal. It is good to do so.

  In addition, when the number of days until the next leap second update date has already passed, it is possible to indicate that the update date has passed by setting the data relating to this number of days to zero. In addition, by setting the data related to the number of days to 0, it can be shown that leap seconds are not inserted on January 1 or July 1, which is normally the leap second update date.

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

  The reception circuit 20 that has calculated the difference data sends 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 acquired in step S22. HOW data.

  Thereafter, in step S27, the control circuit 30 issues a command to stop activation of the receiving circuit 20 by turning off the switch 41. When the switch 41 is turned off in step S27, the control circuit 30 sends the instruction to the receiving circuit 20 in step S28. 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 leap second update unit 35 may update the leap second using any method. As an example, first, the leap second update 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 updates the updated leap second based on the current leap second offset value Δt _LS and the data indicating whether to advance (+) or delay by one second (−) at the next leap second update. The leap second offset value Δt _LSF is calculated and stored in the storage medium in the control circuit 30 as well.

Furthermore, 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), Based on the internal time generated by the internal time generation unit 32 or the time information received from the receiving 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, if the leap second update unit 35 determines that the data regarding 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-existing day (for example, February 30 , November 31 etc.).

When the internal time generated by the internal time generation unit 32 matches the update date DN, 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 leap second reception operation of the satellite radio timepiece W according to the present embodiment.

  In the example illustrated in FIG. 6, first, the control circuit 30 refers to the internal time generated by the internal time generation unit 32 in step S <b> 31, and the satellite signal received by the antenna 10 includes leap second information. Wait for timing, in other words, just before receiving the fourth subframe of the frame of the 18th page, and 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 Turned on based on this command.

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

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

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

  The reception circuit 20 that has calculated the difference data sends 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.

  Thereafter, in step S36, the control circuit 30 issues a command to stop activation of the receiving circuit 20 by turning off the switch 41. When the switch 41 is turned off in step S36, the control circuit 30 sends the instruction to the receiving circuit 20 in step S37. 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, a description thereof is omitted here.

  Note that the operations in step S31 and step S32 in FIG. 6 correspond to an activation control unit that activates the reception circuit 20 at a timing at which the reception circuit 20 receives information about leap seconds.

  In the satellite radio timepiece W according to the present embodiment configured as described above, the difference data calculation unit 23 of the reception circuit 20 includes the week number information stored in the week number storage unit 34 of the control circuit 30 and the time information. The difference data from the predetermined time to the timing at which the leap second is updated is calculated based on the leap second information included in the data and output to the control circuit 30.

  Therefore, it is possible to reduce the data transmitted from the receiving circuit 20 to the control circuit 30 for the leap second reception operation, and thereby, as much as possible the burden on the control circuit 30 that performs the leap second reception operation based on the data. Can be reduced.

  That is, as shown in FIG. 7B, in a general satellite radio timepiece, 30-bit data is transmitted from the receiving circuit 20 to the control circuit 30 as leap second information. This is the present embodiment. According to the satellite radio timepiece W, as shown in FIG. 7C, this can be reduced to 17-bit data. Thereby, the burden of the leap second update part 35 based on the reduced data can be reduced as much as possible.

  In the satellite radio-controlled timepiece W according to the present embodiment, the differential data calculation operation is performed by the reception circuit 20. However, since the reception circuit 20 is usually more sophisticated than the control circuit 30, There is no major problem in causing the difference data calculation unit 23 to perform the difference data calculation operation.

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

  The embodiment of the present invention has been described in detail above with reference to the drawings. However, the specific configuration is not limited to the embodiment and the example, and the design change is within a range not departing from the gist of the present invention. Are included in the present invention.

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

  Although the description has been given assuming that the reception time is 6 seconds at the maximum, the reception time is not limited to this and may be set to an arbitrary time. For example, the start timing is set so that the preamble of the subframe 4 on page 18 can be acquired in consideration of the start-up time of the receiving circuit 20 and the time taken to acquire the satellite, and reception is performed for 6 seconds or more. You may do it.

  When receiving satellite radio waves, it is easily affected by the influence of the reception environment, and there is a possibility that reception may fail in an environment where buildings are densely located indoors or around. Therefore, it may be configured to determine whether or not the reception environment is prepared before starting reception, and to start reception when the reception environment is prepared. For example, the intensity 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 determination is made according to each value. If it is determined that the reception environment is not suitable, it may wait for 12.5 minutes and acquire leap second data at the next reception timing.

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 a satellite signal transmitted from a satellite and outputs time information;
In a satellite radio timepiece having a control circuit for correcting the 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,
Based on the week number information stored in the week number storage unit and information on leap seconds included in the time information, the reception circuit calculates a difference from a predetermined time to a timing at which the leap seconds are updated. A satellite radio-controlled timepiece having a differential data calculating unit that calculates data and outputs the calculated data to the control circuit.   2. The difference data includes the number of days from the predetermined time to the next leap second update date, and the difference seconds between the current leap second and the updated leap second. Satellite radio clock.   3. The satellite radio timepiece according to claim 1, wherein the control circuit includes an activation control unit that activates the reception circuit at a timing at which the reception circuit receives information on the leap second.   The satellite radio timepiece according to claim 1, wherein the control circuit includes 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,
5. 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 using the week number information output from the receiving circuit. clock. The week number information is reset when a predetermined value is exceeded,
The satellite radio timepiece according to claim 1, wherein the week number storage unit includes a rollover count unit in which the number of resets of the week number information is stored.