TimeKeeping Device and Satellite Signal Reception Method for a Timekeeping Device

• US 20090160705A1
• Filed: 12/10/2008
• Published: 06/25/2009
• Est. Priority Date: 12/19/2007
• Status: Active Grant

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Matsuzaki, Jun
• Granted Patent: US 8,116,170 B2
• Time in Patent Office: Days
• US Class Current: 342/357.520
• CPC Class Codes: G01S 19/14 specially adapted for specific applications
• CPC Class Codes: G01S 19/24 Acquisition or tracking or demodulation of signals transmitted by the system synchronisation aspects of direct sequence spread spectrum modulation H04B1/7073
• CPC Class Codes: G01S 19/34 Power consumption
• CPC Class Codes: G04R 20/04 Tuning or receiving; Circuits therefor

Abstract

A timekeeping device has a reception unit that captures a positioning information satellite and receives satellite signals transmitted from the captured positioning information satellite, a time information generating unit that generates time information based on the satellite signal received by the reception unit, a time display unit that displays time information, and a reception control unit that controls the reception unit. The reception control unit includes a satellite capture control unit that controls the reception unit to run the positioning information satellite capture process, a signal condition detection unit that detects the signal condition of the captured positioning information satellite, a decoding control unit that controls the reception unit to apply a decoding process to the satellite signal transmitted from the captured positioning information satellite, and a reception channel setting unit that sets the reception unit to a single satellite mode or a multi-channel mode based on the signal condition detected by the signal condition detection unit, and the reception unit sets the number of positioning information satellites that can be simultaneously captured and decoded to 1 when set to the single satellite mode, and sets the number of positioning information satellites that can be simultaneously captured and decoded to more than 1 when set to the multi-channel mode.

Claims

1. A timekeeping device, comprising:

a reception unit that captures a positioning information satellite and receives satellite signals transmitted from the captured positioning information satellite;

a time information generating unit that generates time information based on the satellite signal received by the reception unit;

a time display unit that displays time information; and

a reception control unit that controls the reception unit;

wherein the reception control unit includes

a satellite capture control unit that controls the reception unit to run the positioning information satellite capture process,

a signal condition detection unit that detects the signal condition of the captured positioning information satellite,

a decoding control unit that controls the reception unit to apply a decoding process to the satellite signal transmitted from the captured positioning information satellite, and

a reception channel setting unit that sets the reception unit to a single satellite mode or a multi-channel mode based on the signal condition detected by the signal condition detection unit; and

wherein the reception unit sets the number of positioning information satellites that can be simultaneously captured and decoded to 1 when set to the single satellite mode, and sets the number of positioning information satellites that can be simultaneously captured and decoded to more than 1 when set to the multi-channel mode.

2. The timekeeping device described in claim 1, wherein the reception channel setting unit sets the reception unit to the single satellite mode at the start of reception and captures one positioning information satellite, detects the signal condition of the positioning information satellite captured in the single satellite mode by the signal condition detection unit, and then based on the detected signal condition continues processing in the single satellite mode or switches from the single satellite mode to the multi-channel mode.

3. The timekeeping device described in claim 1, wherein the reception channel setting unit switches to the multi-channel mode if the signal strength of the captured positioning information satellite is less than a set threshold level when the reception unit is set to the single satellite mode.

4. The timekeeping device described in claim 3, wherein the reception channel setting unit sets the reception channel count in the multi-channel mode based on the signals strength of the captured positioning information satellite.

5. The timekeeping device described in claim 1, wherein the reception channel setting unit switches to the multi-channel mode if the signal strength of the captured positioning information satellite is greater than or equal to the set threshold level when the reception unit is set to the single satellite mode but the time information could not be decoded from the satellite signal within a predetermined decoding time-out determination time.

6. The timekeeping device described in claim 5, wherein the reception channel setting unit sets the decoding time-out determination time according to the signal strength of the captured positioning information satellite.

7. The timekeeping device described in claim 1, wherein the reception channel setting unit switches to the multi-channel mode if variation in the signal strength exceeds a set range while decoding the satellite signal when the reception unit is set to the single satellite mode even if the signal strength of the captured positioning information satellite is greater than or equal to the set threshold level.

8. The timekeeping device described in claim 1, wherein the satellite capture control unit sets the positioning information satellite capture frequency to a plurality of ranges and captures positioning information satellites in each frequency range when the reception unit is set to the multi-channel mode.

9. The timekeeping device described in claim 1, wherein:

the satellite capture control unit ends the satellite capture process when the set number of positioning information satellites is captured or the signal strength of the captured positioning information satellite is greater than or equal to the set threshold level when the reception unit is set to the multi-channel mode; and

the decoding control unit causes decoding of the satellite signal from the captured positioning information satellite after the satellite capture process ends.

10. The timekeeping device described in claim 1, wherein:

the satellite capture control unit executes the positioning information satellite capture process on each reception channel when the reception unit is set to the multi-channel mode;

the decoding control unit applies the decoding process to the satellite signal from the captured positioning information satellite, and determines if time information was decoded and acquired; and

the satellite capture control unit ends the satellite capture process if the time information is decoded and acquired on any reception channel.

11. The timekeeping device described in claim 1, further comprising:

an internal time information generating unit that generates internal time information; and

a time information adjusting unit that adjusts the internal time information;

wherein the time information adjusting unit adjusts the internal time information based on the time information that is generated by the time information generating unit based on the satellite signal received by the reception unit.

12. A timekeeping device, comprising:

a reception unit that captures a positioning information satellite and receives satellite signals transmitted from the captured positioning information satellite;

a time information generating unit that generates time information based on the satellite signal received by the reception unit;

a time display unit that displays time information; and

a reception control unit that controls the reception unit;

wherein the reception control unit includes

an evaluation unit that evaluates the reception environment of the timekeeping device before the reception process executes; and

a search mode selection unit that selects a single satellite search mode or a plural satellite search mode based on the result from the evaluation unit when the reception unit runs the reception process,

the single satellite search mode being a mode for capturing one positioning information satellite and acquiring time information based on the satellite signal transmitted from the captured positioning information satellite, and

the plural satellite search mode being a mode for capturing a plurality of positioning information satellites and acquiring time information based on the satellite signal transmitted from one of the plural captured positioning information satellites.

13. The timekeeping device described in claim 12, further comprising:

a light measuring unit that measures the amount of light illuminating the timekeeping device;

wherein the evaluation unit determines if the amount of light measured by the light measuring unit is greater than or equal to a predetermined threshold level; and

the search mode selection unit selects the single satellite search mode if the evaluation unit determines that the measured amount of light is greater than or equal to the predetermined threshold level, and selects the plural satellite search mode if the measured amount of light is less than the predetermined threshold level.

14. The timekeeping device described in claim 12, further comprising:

a speed measuring unit that measures the speed of timekeeping device movement;

wherein the evaluation unit determines if the speed of movement measured by the speed measuring unit is less than or equal to a predetermined threshold level; and

the search mode selection unit selects the single satellite search mode if the evaluation unit determines that the speed of movement is less than or equal to the predetermined threshold level, and selects the plural satellite search mode if the measured amount of light is greater than the predetermined threshold level.

15. The timekeeping device described in claim 12, further comprising:

a storage unit that stores orbit information for the positioning information satellites;

wherein the evaluation unit determines based on the orbit information stored in the storage unit if among the positioning information satellites that can be captured when the reception process is executed there is at least a predetermined number of positioning information satellites located at a high elevation angle greater than or equal to a predetermined angle; and

the search mode selection unit selects the single satellite search mode if the evaluation unit determines that there is at least the predetermined number of positioning information satellites located at the high elevation angle, and selects the plural satellite search mode if there is fewer than the predetermined number of satellites.

16. The timekeeping device described in claim 12, further comprising:

a reception level detection unit that detects a reception level of the satellite signal received from a positioning information satellite; and

a storage unit that stores the reception level detected by the reception level detection unit;

wherein the evaluation unit determines if the reception level stored in the storage unit during the previous reception process is greater than or equal to a predetermined level; and

the search mode selection unit selects the single satellite search mode if the evaluation unit determines that the reception level during the previous reception process is greater than or equal to the predetermined level, and selects the plural satellite search mode if the reception level is less than the predetermined level.

17. The timekeeping device described in claim 12, further comprising:

a reception time measuring unit that measures the reception time from when a satellite signal from a positioning information satellite is received until the time information is acquired; and

a storage unit that stores the reception time measured by the reception time measuring unit;

wherein the evaluation unit determines if the reception time during the previous reception process stored in the storage unit is less than or equal to a predetermined level; and

the search mode selection unit selects the single satellite search mode if the evaluation unit determines that the reception time during the previous reception process is less than or equal to the predetermined level, and selects the plural satellite search mode if the reception level is longer than the predetermined level.

18. The timekeeping device described in claim 12, further comprising:

an external operating member that can be operated by a user;

wherein the evaluation unit determines if the external operating member was operated to select the single satellite search mode or the plural satellite search mode; and

the search mode selection unit selects the single satellite search mode if the evaluation unit determines that an operation selecting the single satellite search mode was performed, and selects the plural satellite search mode if an operation selecting the plural satellite search mode was performed.

19. The timekeeping device described in claim 18, wherein:

the search mode selection unit selects the single satellite search mode if the evaluation unit determines that neither an operation selecting the single satellite search mode or an operation selecting the plural satellite search mode was performed.

20. A satellite signal reception method for a timekeeping device having a reception unit that captures a positioning information satellite and receives satellite signals transmitted from the captured positioning information satellite,a time information generating unit that generates time information based on the satellite signal received by the reception unit, a time display unit that displays time information, and a reception control unit that controls the reception unit, the satellite signal reception method comprising:

capturing the positioning information satellite;

detecting the signal condition of the positioning information satellite captured in the satellite capture step;

decoding the satellite signal transmitted from the positioning information satellite captured in the satellite capture step; and

setting the reception unit based on the signal condition detected in the signal condition detection step to a single satellite mode in which the number of positioning information satellites that can be simultaneously captured and decoded is 1, or a multi-channel mode in which a plural number of positioning information satellites can be simultaneously captured and decoded.