Japanese Patent application No. 2007-002727 is hereby incorporated by reference in its entirety.
1. Field of Invention
The present invention relates to a time adjustment device that adjusts the time based on time information contained in signals transmitted from the base station of a CDMA (Code Division Multiplex Access) cell phone network, for example. The invention also relates to a timepiece having the time adjustment device, and to a time adjustment method.
2. Description of the Related Art
Time information is contained in signals transmitted to cell phones from the base stations in modern CDMA cell phone networks. This time information is extremely precise time information that matches the GPS time, which is based on the atomic clocks on GPS (Global Positioning System) satellites.
Japanese Unexamined Patent Appl. Pub. JP-A-2000-321383 (see the abstract) teaches a terminal that acquires the GPS time data transmitted from a base station of a CDMA cell phone network, and uses the GPS time data to correct the time kept by an internal clock.
The time information the time adjustment device receives from the base station includes a leap seconds correction time. This leap seconds value is a correction time for adjusting the GPS time to account for error caused by the Earth's rotation.
The leap seconds value is a correction time that is set flexibly according to the rotation of the Earth, and the leap seconds value that is registered in the base station is typically adjusted twice a year.
However, the leap seconds value is actually applied to the time from July 1 and January 1, for example.
Because adjusting the leap seconds value in each base station simultaneously to the time the leap seconds is applied is difficult, the base station leap seconds value is normally corrected sometime before, such as up to six months before, the leap seconds value is actually applied.
The leap seconds data is therefore incorrect for the period until the adjusted leap seconds data is actually applied after the leap seconds data is corrected at the base station.
As a result, the time adjustment device cannot adjust the time correctly during this period if the time is adjusted using the leap seconds data received from the base station.
The time adjustment device, the timepiece having the time adjustment device, and the time adjustment method of the invention enable accurately reflecting the leap seconds data acquired from the base station when adjusting the time.
A first aspect of the invention is a time adjustment device having a reception unit that receives a prescribed signal containing time information transmitted by a base station, a display time information adjustment unit that adjusts the time information displayed by a time information display unit based on the time information, a leap seconds information storage unit for storing leap seconds information that is time adjustment information based on rotation of the Earth and is contained in the time information, and a leap seconds application time information storage unit that stores leap seconds application time information for adjusting the displayed time information based on the leap seconds information. The display time information adjustment unit corrects the displayed time information based on the leap seconds information and the leap seconds application time information.
This aspect of the invention has a leap seconds information storage unit for storing leap seconds information that is time adjustment information based on rotation of the Earth and is contained in the time information, and a leap seconds application time information storage unit that stores leap seconds application time information for adjusting the displayed time information based on the leap seconds information, and the display time information adjustment unit corrects the displayed time information based on the leap seconds information and the leap seconds application time information.
As a result, if the time adjustment device gets the leap seconds information before the leap seconds information should be used, the received leap seconds information is not used immediately to adjust the displayed time information and the displayed time information is instead adjusted based on the leap seconds information when the leap seconds information is to be used.
The leap seconds information acquired from the base station can therefore be accurately reflected in the time adjustment.
Preferably, the time adjustment device also has a leap seconds change determination unit that determines if the leap seconds information received from the base station has changed. The display time information adjustment unit adjusts the displayed time information based on the leap seconds application time information and the leap seconds information that the leap seconds change determination unit has evaluated for change.
This aspect of the invention has a leap seconds change determination unit that determines if the leap seconds information received from the base station has changed, and the display time information adjustment unit adjusts the displayed time information based on the leap seconds application time information and the leap seconds information that the leap seconds change determination unit has evaluated for change.
If the leap seconds information is changed at the base station before the leap seconds information is to be applied, this change is recognized by the leap seconds change determination unit. The leap seconds information that is recognized as having changed is then used when the information should be applied when the display time information adjustment unit adjusts the displayed time information. When the changed leap seconds information should be applied is determined based on the leap seconds application time information.
The leap seconds application time can thus be managed more accurately.
Further preferably, the time adjustment device also has a base station leap seconds information storage unit that stores the leap seconds information received from the base stations as base station leap seconds information separated into leap seconds information for each base station, and a base station leap seconds reference information generating unit that generates base station leap seconds reference information based on the base station leap seconds information. The leap seconds change determination unit determines if the leap seconds information received from the base stations has changed based on the base station leap seconds reference information.
This aspect of the invention has a base station leap seconds information storage unit that stores the leap seconds information received from the base stations as base station leap seconds information separated into leap seconds information for each base station, and a base station leap seconds reference information generating unit that generates base station leap seconds reference information based on the base station leap seconds information, and the leap seconds change determination unit determines if the leap seconds information received from the base stations has changed based on the base station leap seconds reference information.
As a result, if the leap seconds information is different for each base station, the leap seconds information can still be applied with good precision to adjust the displayed time information.
Further preferably, the base station reference leap seconds change determination unit applies an averaging process or statistical process to the base station leap seconds information.
Yet further preferably, the time adjustment device also has a time information extraction signal supply unit that supplies only a time information extraction signal, and the time information is extracted from the prescribed signal using the time information extraction signal.
This aspect of the invention has a time information extraction signal supply unit that supplies only the time information extraction signal used for extracting time information from the prescribed signal containing time information transmitted by a base station. The size of the circuit rendering this time information extraction signal supply unit can therefore be reduced compared with the related art, and the power consumption of the time adjustment device can be reduced.
Yet further preferably, the time information is future time information for a specific time after the reception time information, which is the time the reception unit receives, and the time adjustment device also has a time difference information storage unit that stores the time difference between the future time information and the reception time information, a reception time information generating unit that generates the reception time information of the reception unit based on the future time information received by the reception unit and the time difference information, and an adjustment time information generating unit that generates adjustment time information for adjusting the display time information adjustment unit based on the reception time information generated by the reception time information generating unit and at least processing time information for the time adjustment device.
Another aspect of the invention is a timepiece device having a time adjustment device, including a reception unit that receives a prescribed signal containing time information transmitted by a base station, a display time information adjustment unit that adjusts the time information displayed by a time information display unit based on the time information, a leap seconds information storage unit for storing leap seconds information that is time adjustment information based on rotation of the Earth and is contained in the time information, and a leap seconds application time information storage unit that stores leap seconds application time information for adjusting the displayed time information based on the leap seconds information. The display time information adjustment unit corrects the displayed time information based on the leap seconds information and the leap seconds application time information.
Another aspect of the invention is a time adjustment method for a time adjustment device including a reception unit that receives a prescribed signal containing time information transmitted by a base station, and a display time information adjustment unit that adjusts the time information displayed by a time information display unit based on the time information. The display time information adjustment unit corrects the displayed time information based on leap seconds information that is time adjustment information based on rotation of the Earth and contained in the time information, and leap seconds application time information for adjusting the displayed time information based on the leap seconds information.
Other objects and attainments together with a fuller understanding of the invention will become apparent and appreciated by referring to the following description and claims taken in conjunction with the accompanying drawings.
A preferred embodiment of the present invention is described below with reference to the accompanying figures.
The embodiment described below has various technically desirable limitations because it is a specific preferred embodiment of the invention, but the scope of the invention is not limited to the following embodiment unless some aspect described below is specifically said to limit the invention.
As shown in
As also shown in
The wristwatch 10 in this embodiment of the invention does not have a cell phone function and therefore does not enable voice communication with the CDMA base stations 15a, but receives time information, for example, from the signals transmitted from the CDMA base stations 15a and adjusts the time based on these received signals. The content of the signals from the CDMA base stations 15a is further described below.
As also shown in
This crown 28 is an example of an external input unit that can be operated by the user.
The hardware arrangement of the wristwatch 10 is described next.
As shown in
A reception unit for receiving signals from the CDMA base stations 15a, such as CDMA base station signal receiver 24, is connected to the bus 20. The CDMA base station signal receiver 24 has the antenna 11 shown in
A real-time clock (RTC) 25 that is a timekeeping mechanism rendered as an IC device (semiconductor integrated circuit), for example, and a crystal oscillator with temperature compensation circuit (TCXO) 26, are also connected to the 20.
The dial 12 and hands 13 shown in
A battery 27 is also connected to the bus 20, and the battery 27 is a power supply unit for supplying power for communication by the reception unit (such as the CDMA base station signal receiver 24).
The display 14 and the crown 28 shown in
A start timing generator 17b is also connected to the pilot PN synchronization unit 17a. The pilot PN synchronization unit 17a inputs the timing at which the signal was synchronized to the start timing generator 17b, and based on this input the start timing generator 17b generates the start timing.
As shown in
As further described below, the divide-by-64 counter 17c divides the frequency of the pilot PN chip rate, that is, 1.2288 MHz, by 64 and generates Walsh code (32). The resulting Walsh code (32) is mixed with the sync channel signal received by the antenna 11 to extract the time information. Processing these signals is described below.
The start timing generator 17b is an example of a start timing supply unit that supplies the start timing at which the divide-by-64 counter 17c starts frequency dividing the base frequency of, for example, the pilot PN chip rate (1.2288 MHz).
The divide-by-64 counter 17c is a frequency division counter unit that frequency divides the basic unit of a prescribed signal, such as the 1.2288 MHz frequency of the pilot PN signal, and generates a time information extraction signal, such as Walsh code (32).
The baseband unit 17 also has a digital filter 17d and a deinterleaving and decoding unit 17e as shown in
As shown in
Note that the program storage unit 30, the first data storage unit 40, and the second data storage unit 50 are shown separately in
In addition, primarily data that is predefined is stored in the first data storage unit 40 in
While describing the operation of the wristwatch 10 according to this embodiment of the invention with reference to the flow charts in
Before proceeding to the description of the flow charts, the parts of the CDMA cell phone system that are related to the invention are described below.
The CDMA cell phone system started actual operation after the system developed by Qualcomm, Inc. of the United States was adopted in 1993 as the IS95 cell phone standard in the United States. This standard was later revised as IS95A, IS95, and then CDMA2000. A cell phone system conforming to ARIB STD-T53 is used in Japan.
Because the CDMA system is synchronized on the downlink (from the CDMA base station 15a to the mobile station, wristwatch 10 in this embodiment of the invention), the wristwatch 10 must synchronize with the signals from the CDMA base station 15a. The signals transmitted from the CDMA base station 15a include a pilot channel signal and a sync channel signal. The pilot channel signal is a signal that is transmitted from each CDMA base station 15a at a different timing, such as the pilot PN signal.
Because the signals transmitted form the CDMA base stations 15a and 15b are the same, the signal transmission timing of each CDMA base station 15a differs from the signal transmission timing of each other CDMA base station 15a so that it can be determined which CDMA base station 15a transmitted a particular signal.
More specifically, these timing differences are expressed by differences in the pilot PN signal transmitted by the CDMA base station 15a. In
By each CDMA base station 15a providing a different pilot PN offset that is an integer multiple of 64 chips, the wristwatch 10 can easily determine the CDMA base station 15a from which a signal was received even when there are many CDMA base stations 15a.
The signals transmitted from the CDMA base station 15a also contain a sync channel signal, which is the sync channel message shown in
As shown in
The sync channel message also contains system time information, which is the GPS time.
The system time is the cumulative time in 80 ms units from 0:00 on Jan. 6, 1980. This value is contained in the SYS_TIME field in
The sync channel message also contains a leap second value for UTC (Universal Time Code) conversion. This value is contained in the LP_SEC field in
The sync channel message also contains the local offset time, which is the time difference between the country or region where the wristwatch 10 is located and the UTC. If the country is Japan, for example, a value indicating that the time difference to UTC is +9 hours is stored.
This value is stored in the LTM_OFF field in
The sync channel message also contains a daylight savings time value indicating if the country or region where the wristwatch 10 is located uses daylight savings time. The value in this example is 0 because Japan does not use daylight savings time. This value is stored in the DAYLT field in
The pilot PN signal data shown in
While the sync channel message shown in
The GPS time in the sync channel message shown in
More specifically, the GPS time is the time at four superframes from the time at the end of the last superframe referenced to the time when the above-described pilot PN offset is 0 chips (0 ms).
This is based on CDMA being a cell phone telecommunication system. More specifically, after the cell phone receives the sync channel message shown in
That is, after preparing to shift to the next stage, standby, the cell phone synchronizes and communicates with the CDMA base station 15a.
Therefore, if the CDMA base station 15a sends a time in the future, such as the time 320 ms later, in advance to allow for this preparation time, and the cell phone receiving this time executes an internal process to prepare for communication and then attempts to synchronize with the CDMA base station 15a, synchronization is easier. In other words, these four superframes (320 ms) are preparation time for the cell phone.
The CDMA cell phone system used by this embodiment of the invention is described above, and the embodiment of the invention is described below with reference to this CDMA cell phone system.
To adjust the time of the wristwatch 10, the CDMA base station signal receiver 24 shown in
Then, in ST2, the CDMA base station signal receiver 24 receives the pilot channel signal from the CDMA base station 15a. More specifically, the pilot channel signal reception program 31 in
The pilot PN code is then mixed with the received pilot channel signal to synchronize in ST3 in
More specifically, the pilot synchronization program 32 in
Because the pilot PN code is thus contained in the received pilot channel signal, the CDMA base station signal receiver 24 requires the same pilot PN code and Walsh code (0) to receive. The CDMA base station signal receiver 24 can thus synchronize with the pilot channel signal from the CDMA base station 15a, despread, and get data.
As shown in
Signals synchronized this way are synchronized with a superframe every 80 ms as described in
The pilot PN synchronization program 32 then determines if synchronization with the pilot channel signal of the CDMA base station 15a is completed in ST4. If synchronization is not finished, the CDMA base station signal receiver 24 determines in ST5 if all service area tables in the wristwatch 10 have been referenced (through one cycle), and if they have not been referenced, control goes to ST6.
The data for CDMA base stations 15a in Japan, the United States, China, and Canada, for example, is referenced in ST6, and the pilot channel is scanned in ST1 based on this data.
For example, if the wristwatch 10 is looking for a CDMA base station 15a in Japan but is actually in the United States, synchronization with the pilot channel is not possible in ST3. Data for the CDMA base stations 15a in the United States is then acquired in ST6, and the pilot channel is scanned in ST1 based on this data.
However, is synchronization with the pilot channel signal is not possible even though all service area tables in the wristwatch 10 have been referenced in ST6, control goes to ST7. To indicate for the user that the time has not been adjusted, the seconds hand in
If synchronization with the pilot channel signal is completed in ST4, control goes to ST8 and the start timing generator 17b inputs the start timing to the divide-by-64 counter 17c.
In this case the start timing generator control program 33 in
This is shown and described more specifically in
As shown in the figure, the divide-by-64 counter in
In ST9 the divide-by-64 counter 17c starts operating and frequency dividing at the start timing input from the start timing generator 17b
In this case the divide-by-64 counter 17c operates according to the divide-by-64 counter control program 34 in
The length of this code is 64 chips including a 0 signal for the first 32 chips and a 1 signal for the second 32 chips, and is thus the same as the Walsh code (32) for getting data from the sync channel message in
As shown in
When this 1.2288 MHz signal is divided by 64 by the frequency division counter 17c the result is the Walsh code (32) of which the 32 chips in the first half are 0s and the 32 chips in the second half are 1s as shown in
In ST9, the pilot PN code is first mixed with the sync channel signal, that is, the signal received form the CDMA base station 15a, and the signal is despread using the Walsh code (32) generated by the divide-by-64 counter 17c at the synchronization timing that can be recognized from the beginning of the pilot PN code. The signal is then passed through the digital filter 17d and deinterleaving and decoding unit 17e to get the sync channel message in
As shown in
The divide-by-64 counter 17c in
In this embodiment of the invention as shown in
Whether receiving the sync channel message is completed is then determined in ST10. If sync channel message reception is not completed, whether reception timed out is determined in ST11. If reception timed out, the sync channel message is received again in ST8.
This embodiment of the invention can thus generate the Walsh code (32) that is required to extract the sync channel message from the sync channel signal transmitted from the CDMA base station 15a by means of the divide-by-64 counter 17c, and does not require a Walsh code generator to generate the 64 types of Walsh codes as is required by the related art.
The circuit synchronize can therefore be reduced and power consumption can be reduced.
More specifically, the divide-by-64 counter 17c in this embodiment of the invention can generate the Walsh code (32) as shown in
In addition, because frequency dividing by the divide-by-64 counter 17c is based on the start timing signal from the start timing generator 17b, which is referenced to the pilot PN signal synchronization timing, the sync channel message can be reliably extracted from the sync channel signal.
If it is determined in ST10 that sync channel message reception finished, control goes to ST12 and signal reception by the CDMA base station signal receiver 24 in
This results in the wristwatch 10 receiving the entire sync channel message shown in
Control then goes to ST13. From ST13 is the process for producing the time adjustment data and actually adjusting the time based on information in the sync channel message already acquired from the CDMA base station 15a.
The data for adjusting the time is produced using the leap seconds data shown in
More specifically, the GPS time (SYS_TIME) is a time value that does not consider the Earth's rotation, the time must therefore be corrected to get the actual time on Earth, and this adjustment data is the leap seconds value. However, this leap seconds data is typically not accurately changed at the CDMA base station 15a when the data is implemented, such as at 0:00 or 9:00 a.m. on January 1, and the CDMA base station 15a data is usually changed sometime before, such as approximately a maximum six months in advance.
If the leap seconds value that is to be applied from 0:00 on January 1 of the next year is “14 seconds,” for example, and the leap seconds value used until then is “13 seconds,” the new leap seconds value of “14 seconds” is already changed in the sync channel data in July of the previous year.
As a result, the time will be 1 second late until 0:00 on January 1 of the next year, and the time cannot be accurately adjusted.
The following process is therefore executed.
First, in ST13, the GPS time SYS_TIME and the leap seconds LP_SEC, such as “14” seconds, are first acquired from the received sync channel message (sync channel message 51a in
The UTC is the year, month, day, hour, minute, and second of Greenwich Mean Time.
More specifically, the UTC time calculation program 312 in
The calculated UTC time is then stored as the UTC time data 57a in
Whether the leap seconds data that was received differs from the registered leap seconds data is then determined in ST14.
More specifically, a registered received leap seconds data storage unit 59 that stores the registered received leap seconds data 59a is provided in the second data storage unit 50 as shown in
The leap seconds comparison program 314 in
For example, the registered received leap seconds data of 13 seconds was received on August 20, and 14 seconds is received as the current leap seconds data on August 30, the registered received leap seconds data and the currently received leap seconds data are different.
In this case the “14 second” value is known to be the leap seconds value that should be used, for example, from 0:00 of January 1 of the next year.
The registered received leap seconds data storage unit 59 and the sync channel message data storage unit 51 are thus an example of a leap seconds information storage unit. The leap seconds comparison program 314 is an example of a leap seconds change determination unit.
The registered received leap seconds data 59a can also be manually corrected by the user of the wristwatch 10.
If the leap seconds data is determined to be different in ST14, the leap seconds data that was received has changed and is the value for the next year, for example. Whether this leap seconds data should be used or not is then determined in ST15.
Whether the UTC time data 57a indicates 23:59:59 on June 30 or December 31 is then determined in ST15.
More specifically, whether the time has come when the currently received leap seconds data that was received in ST9 should actually be used (applied) is determined.
More specifically, the leap seconds correction determination program 316 makes this decision based on the UTC time data 57a in
The leap seconds correction time data storage unit 48 in
If in ST15 the UTC time data 57a indicates the time when the received leap seconds value is to be used, the leap seconds data that was just received (such as “14 seconds” in this example) is stored as the registered received leap seconds data 59a (ST16), and control goes to ST17.
In ST17 the current-reception-based first local time data 52a in
The current-reception-based first local time data 52a is described next.
Because the wristwatch 10 in this embodiment of the invention is in Japan, for example, the GPS time, the currently received leap seconds, local offset time (UTC+9 in the case of Japan), and daylight savings time adjustment (0 hours in this example because there is no daylight savings time in Japan) are extracted from the sync channel message data 51a in
More specifically, the UTC is calculated referenced to the GPS time and the current received leap seconds data, for example, and the local time is calculated by adding the local offset time to the UTC time. In this example 9 hours is added to the UTC time to get Japan time. Because daylight savings time is not used in Japan, there is no adjustment for daylight savings time. In countries such as the United States where daylight savings time is used, the corrected daylight savings time is set with extremely high precision.
The current-reception-based first local time data 52a thus calculated is then stored in the current-reception-based first local time data storage unit 52 in
The current-reception-based first local time data 52a thus uses the leap seconds data that was changed by the CDMA base station 15a, but this leap seconds value is applied at the correct time so that the time information is highly precise.
If the currently received leap seconds data does not differ from the registered leap seconds data in ST14, that is, even when the leap seconds values are the same, the first local time is calculated in ST17.
Unlike when ST16 returns Yes, however, the currently received leap seconds data has not been changed by the CDMA base station 15a. In this case, therefore, the current-reception-based first local time data 52a is calculated in ST17 based on a leap seconds value that has not changed.
If ST15 returns No, that is, the UTC time data 57a is not the specified time on June 30 or December 31, the currently received leap seconds data has changed but is not the leap seconds data to be applied at the current time.
If the time is adjusted using the currently received leap seconds data in this case, the time will be slow by the amount that the leap seconds value has changed, that is, by 1 second in the above example, and the time cannot be adjusted accurately.
Therefore, if ST15 returns No, this embodiment of the invention goes to ST18. Step ST18 calculates the registered-reception-based first local time data 58a based on the registered received leap seconds data 59a in
As a result, the leap seconds data that matches the period when it should be applied is used to produce the data for adjusting the time, and the time can be prevented from being fast or slow by one second as happens with the related art.
This embodiment of the invention thus calculates the current-reception-based first local time data or the registered-reception-based first local time data as the first Japan time, and this time is the basic time based on the GPS time and the leap seconds data that is applicable to when the time is being set.
The current-reception-based first local time data 52a that is calculated here is described next. The current-reception-based first local time data 52a is described with reference to
When the wristwatch 10 receives the signal from the CDMA base station 15b in
However, because the pilot PN offset of signals transmitted from the CDMA base station 15b in
The invention therefore executes the following process. That is, the first local time data 52a in
The time, Japan time in this example, can therefore be generated based on the correct GPS time at the end of reception (EE) of the last superframe.
The second local time calculation program 37 in
An example of the time difference data 44a in
An example of the pilot PN offset time data 45a is the value of 64 chips (0.052 ms) used above, and is stored in the pilot PN offset time data storage unit 45.
The GPS time acquired from the sync channel message in ST9 is an example of the future time information at a prescribed time after (such as 320 ms after) the reception time information (such as the time at E in
The time difference data 44a in
The first local time calculation program 36 and the second local time calculation program 37 are an example of the reception time information generating unit that generates the reception time information of the reception unit (such as the second local time data 53a) based on the future time information (such as the time at F in
The second local time data 53a calculated in ST19 is a highly precise time matching the GPS time, but because time is required for the calculations done in ST17 or ST18 and ST19, the time differs (is inaccurate) from the precise GPS time by an amount equal to this calculation time.
ST20 is executed to compensate for this calculation time. More specifically, a process delay time is added to the second local time data 53a in
In this embodiment of the invention the process delay time data 46a is therefore stored in the process delay time data storage unit 46 as a constant value as shown in
The resulting final local time data 54a is highly precise time information reflecting the GPS time and the leap seconds value.
Control then goes to ST21. In ST21 the RTC and time adjustment program 39 in
This embodiment of the invention can more accurately adjust the time because the leap seconds data acquired from the CDMA base station 15a is used accurately according to the period when the leap seconds data should be applied.
The RTC and time adjustment program 39 is thus an example of a display time information adjustment unit that adjusts the display time information of the time information display unit (such as the RTC 25 and the hands 13). The final local time calculation program 38 is an example of an adjustment time information generating unit that generates the adjustment time information (such as the final local time data 54a) used for adjustment by the RTC and time adjustment program 39.
As described above the RTC and time adjustment program 39 is an arrangement for adjusting the RTC 25, for example, based on the leap seconds information (such as the currently received leap seconds data) and the leap seconds application time information (including leap seconds correction time data 48a).
The RTC and time adjustment program 39 is also an arrangement for adjusting the RTC 25, for example, based on the leap seconds correction time data 48a and the leap seconds data which the leap seconds comparison program 314 determines if it has changed.
This embodiment of the invention can reduce power consumption from the battery 27 because the CDMA base station signal receiver 24 stops reception of signals from the CDMA base station 15a in ST12.
This is described more specifically with reference to
This compares with the power sequence of this embodiment of the invention denoted by (D) in
Because the wristwatch 10 according to this embodiment of the invention can reduce power consumption, the invention can be used in devices such as timepieces that require very little power while also enabling adjusting the time with extremely high precision.
Control then goes to ST22. A time adjustment interval timer operates in ST22. More specifically, the start time adjustment decision program 311 in
As a result, the next time adjustment process starts 24 hours after the previous time adjustment in ST23, and the process repeats from ST1.
In this case the local offset time that is input using the crown 28 in
The current-reception-based first local time data 52a, for example, is calculated based on this input data in ST17 or ST18 described above, and the time can therefore be adjusted as desired by the user.
This embodiment is described using by way of example adding “1 second” as the leap seconds in the CDMA base station 15a, but the invention is not so limited and includes arrangements in which “1 second” is subtracted.
Furthermore, Walsh code (32) is generated by the divide-by-64 counter 17c, for example, in the above embodiment, but the invention is not so limited. Alternatively, a code signal for the Walsh code (32) shown in
This arrangement enables reducing the circuit size even more, and reduces the power consumption.
The storage unit for the Walsh code (32) in this variation is a time information extraction signal storage unit.
The basic arrangement of the wristwatch with a time adjustment device according to this embodiment of the invention is the same as the wristwatch 10 described in the first embodiment above, like parts are therefore identified by like references, further description thereof is omitted, and primarily the differences between the embodiments are described below.
Whether the leap seconds data sent from the CDMA base station 15a has changed is determined by comparing the currently received leap seconds data with the registered leap seconds data in ST14 in
The first embodiment thus simply compares the leap seconds data that was just received from the CDMA base station 15a with the previously received leap seconds data that is stored internally.
This embodiment of the invention, however, receives and averages, for example, the “currently received leap seconds data” from a plurality of CDMA base stations 15a to get average received leap seconds data, and compares this average value with the previously received and registered leap seconds data.
This is further described below with reference to the figures including
In ST113 in
More specifically, the CDMA base stations 15a are identified using the pilot PN short code (pilot PN offset).
CDMA base stations 15a having different pilot PN short codes such as PN0, PN31, PN5, PN128, and PN255, for example, can therefore be differentiated by the different pilot PN short codes.
The currently received leap seconds data from each CDMA base station 15a is stored correlated to the respective CDMA base station 15a.
More specifically, if 14 seconds is received from PN0, 14 seconds is received from PN31, 14 seconds is received from PN5, 13 seconds is received from PN128, and 13 seconds is received from PN255, for example, the currently received leap seconds data is stored linked to each CDMA base station 15a (for each pilot PN short code).
The base station leap seconds data storage program 601 in
The base station leap seconds data storage unit 701 is thus an example of a base station leap seconds information storage unit.
Then in ST114 in
More specifically, because the received values in this example are 14 seconds from PN0, 14 seconds from PN31, 14 seconds from PN5, 13 seconds from PN128, and 13 seconds form PN255, the average is (14+14+14+13+13)/5=13.6, the decimal part is rounded, and the result is therefore 14 seconds.
The average leap seconds data 702a in
The base station leap seconds data averaging program 602 is thus an example of a base station leap seconds reference information generating unit.
The average leap seconds data 702a and the registered received leap seconds data are then compared in ST115. In the following steps in
This enables the changed leap seconds information to be known more accurately when the leap seconds data is not changed at the same time in all CDMA base stations 15a.
This embodiment of the invention averages the leap seconds values but the invention is not so limited and the number with the greatest statistical distribution, for example, can be used instead of the average leap seconds data 702a in
The invention is not limited to the foregoing embodiment. Whether to apply the leap seconds value is determined above referenced to 23:59:59 on June 30 or December 31, but the invention is not so limited and a reference time of 00:00:00 on July 1 or January 1, or 00:00:30 on July 1 or January 1, can be used.
This arrangement is effective when the CDMA base station 15a inserts (changes) the leap seconds value at 23:59:59 on June 30 or December 31 or later.
The invention being thus described, it will be obvious that it may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.
Number | Date | Country | Kind |
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2007-002727 | Jan 2007 | JP | national |