Position detecting apparatus and method of detecting a position

• US 20070219719A1
• Filed: 05/14/2007
• Published: 09/20/2007
• Est. Priority Date: 05/16/2006
• Status: Active Grant

• Current Assignee: Casio Computer Company Limited
• Original Assignee: Casio Computer Company Limited
• Inventors: Okada, Kunio, Matsuda, Shimpei
• Granted Patent: US 7,778,775 B2
• Time in Patent Office: Days
• US Class Current: 701/213
• 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

Abstract

CPU instructs RF controlling section to switch RF section from an inoperative mode to an operation mode and from the operation mode to the inoperative mode. When all of five pieces of sub-frame data have not been acquired, RF section is switched intermittently from the inoperative mode to the operation mode in synchronization with transmission of lacking sub-frame data, thereby acquiring such lacking sub-frame data. When all the five pieces of sub-frame data have been acquired, the current position is calculated using positional information contained in the sub-frame data. A part of five pieces of sub-frame data including the first to fifth sub-frame data transmitted from a satellite in a time series manner is acquired from GPS signal received in the operation mode, and the remaining part of the five pieces of sub-frame data is acquired in operation mode set at other timing, and then the positional information is judged based on the five pieces of sub-frame data acquired in the above manner.

Claims

1. A position detecting apparatus for receiving GPS signals transmitted from satellites, and for detecting a position using the received PS signals, GPS signal including main frame data and the main frame data of one cycle further including “

m”

pieces of sub-frame data consisting of first sub-frame data to m-th sub-frame data transmitted from the satellite in a time series manner, the apparatus comprising;

a power source for supplying power from a battery;

a receiving unit for receiving GPS signal in an operation mode and for ceasing receiving GPS signal in an inoperative mode, the receiving unit, when kept in the operation mode, being supplied with power from the power source, and the receiving unit, when kept in the inoperative mode, being supplied with no power from the power source;

an operation control unit for switching the receiving unit from the inoperative mode to the operation mode, and for switching the receiving unit from the operation mode to the inoperative mode;

a judging unit for judging whether or not all the “

m”

pieces of sub-frame data have been acquired by the receiving unit, when the receiving unit is switched from the inoperative mode to the operation mode by the operation control unit;

a time calculating unit for, when the judging unit determines that all the “

m”

pieces of sub-frame data have not been acquired, calculating a time at which the receiving unit is to be intermittently switched from the inoperative mode to the operation mode in synchronization with transmission of the sub-frame data which has not been acquired by the receiving unit, and for instructing the operation control unit to control operation of the receiving unit based on the calculated time; and

a position calculating unit for, when the judging unit determines that all the “

m”

pieces of sub-frame data have been acquired, calculating a current position of the apparatus using positional information included in the acquired “

m”

pieces of sub-frame data.

2. The position detecting apparatus according to claim 1, further comprising:

plural storing units for storing sub-frame data, wherein the position calculating unit stores sub-frame data acquired successively from GPS signal received from a satellite by the receiving unit in the storing unit assigned to the satellite based on identifying information of such satellite, and calculates the current position of the apparatus using positional information contained in the “

m”

pieces of sub-frame data stored in the storing units, when appropriate “

m”

pieces of sub-frame data are stored in a predetermined number of storing units.

3. The position detecting apparatus according to claim 1, wherein the operation control unit keeps the receiving unit in the operation mode for a period equivalent to one cycle of the main frame data from a time when a leading synchronizing signal of k-th sub-frame data is detected, where 1≦

“

k”

≦

“

m”

, before receiving an instruction from the time calculating unit to control operation of the receiving unit based on the calculated time.

4. The position detecting apparatus according to claim 3, wherein the judging unit instructs the operation control unit to switch the receiving unit from the inoperative mode to the operation mode, when the leading synchronizing signal of arbitrary sub-frame data has not been detected since a certain period of time lapses after the receiving unit was switched from the inoperative mode to the operation mode by the operation control unit.

5. A method of detecting a position using GPS signals transmitted from satellites, GPS signal including main frame data and main frame data of one cycle further including “

m”

pieces of sub-frame data consisting of from first sub-frame data to m-th sub-frame data transmitted from the satellite in a time series manner, the method comprising;

step A of switching a receiving unit from an inoperative mode to an operation mode and switching the receiving unit from the operation mode to the inoperative mode, the receiving unit being arranged to be supplied with power from a battery in the operation mode to receive GPS signal and to be supplied with no power from the battery in the inoperative mode to cease receiving GPS signal;

step B of judging whether or not all the “

m”

pieces of sub-frame data have been acquired by the receiving unit, when the receiving unit is switched from the inoperative mode to the operation mode at step A;

when it is determined at step B that all the “

m”

pieces of sub-frame data have not been acquired, step C of calculating a time at which the receiving unit is to be intermittently switched from the inoperative mode to the operation mode in synchronization with transmission of the sub-frame data which has not acquired by the receiving unit, and instructing the receiving unit to operate based on the calculated time; and

step D of calculating a current position using positional information included in the acquired “

m”

pieces of sub-frame data, when it is determined at step B that all the “

m”

pieces of sub-frame data have been acquired.

6. The method of detecting a position according to claim 5, wherein, in step D, sub-frame data acquired successively from GPS signal received from a satellite by the receiving unit is stored in a storing unit that is assigned to the satellite based on identifying information of such satellite, and the current position is calculated using positional information contained in the “

m”

pieces of sub-frame data of plural satellites stored respectively in plural storing units, when appropriate “

m”

pieces of sub-frame data are stored in a predetermined number of storing units assigned respectively to plural satellites.

7. The method of detecting a position according to claim 5, wherein, in step A, the receiving unit is kept in the operation mode for a period equivalent to one cycle of the main frame data from a time when a leading synchronizing signal of k-th sub-frame data is detected, where 1≦

“

k”

≦

“

m”

, before an instruction is given at step C to control operation of the receiving unit based on the calculated time.

8. The method of detecting a position according to claim 7, wherein, in step B, an instruction is given to switch the receiving unit from the inoperative mode to the operation mode at step A, when the leading synchronizing signal of arbitrary sub-frame data has not been detected since a certain period of time lapses after the receiving unit was switched from the inoperative mode to the operation mode at step A.

9. A position detecting apparatus comprising:

a power source for supplying power from a battery;

a receiving unit for receiving GPS signal transmitted from a satellite in an operation mode and ceasing receiving GPS signal transmitted from the satellite in an inoperative mode, the receiving unit being supplied with power from, the power source in the operation mode and being supplied with no power from the power source in the inoperative mode;

an operation control unit for intermittently switching the receiving unit from the inoperative mode to the operation mode; and

a judging unit for acquiring a part of “

n”

pieces of particular data from GPS signal received by the receiving unit which is switched into the operation mode by the operation control unit, the “

n”

pieces of particular data consisting of first data to n-th data transmitted from the satellite in a time series manner, and acquiring the remaining pieces of particular data when the receiving unit is switched into the operation mode at other timing, and for judging positional information based on the acquired “

n”

pieces of particular data.

10. The position detecting apparatus according to claim 9, further comprising:

“

n”

units of storing units corresponding respectively to “

n”

pieces of particular data consisting of the first data to “

n”

-th data transmitted from the satellite in a time series manner, wherein the judging unit stores the particular data acquired from GPS signal received by the receiving unit sequentially in the appropriate storing units, and judges positional information, when the particular data are stored in all the “

n”

units of appropriate storing units.

11. The position detecting apparatus according to claim 9, wherein the operation control unit calculates a time at which the receiving unit is switched next time from the inoperative mode to the operation mode, when arbitrary “

m”

-th particular data, where 1≦

“

m”

≦

“

n”

, is received by the receiving unit at the last time in the operation mode.

12. The position detecting apparatus according to claim 9, wherein the operation control unit controls the operation mode, in which the receiving unit can receive at least one “

m”

-th particular data, where 1≦

“

m”

≦

“

n”

, among plural pieces of particular data included in GPS signal.

13. The position detecting apparatus according to claim 9, wherein the “

n”

pieces of particular data consisting of the first data to “

n”

-th data transmitted from the satellite in a time series manner are equivalent respectively to the first to fifth sub-frame data.

14. A method of detecting a position comprising:

step A of receiving GPS signal transmitted from a satellite in an operation mode and ceasing receiving GPS signal transmitted from the satellite in an inoperative mode, in the operation mode power being supplied from a power source including a battery and in the inoperative mode no power being supplied from the power source;

step B of switching intermittently from the inoperative mode to the operation mode; and

step C of acquiring a part of “

n”

pieces of particular data from GPS signal received when the inoperative mode is switched to the operation mode at step B, the “

n”

pieces of particular data including first data to n-th data transmitted from the satellite in a time series manner, and acquiring the remaining pieces of particular data when the inoperative mode is switched to the operation mode at other timing, and judging positional information based on the acquired “

n”

pieces of particular data.

15. The method of detecting a position according to claim 14, further comprising:

step D of storing “

n”

pieces of particular data in “

n”

units of appropriate storing units respectively, the “

n”

pieces of particular data including the first data to “

n”

-th data transmitted from the satellite in a time series manner, wherein, in step D, the particular data acquired from GPS signal received at step A are stored sequentially in the appropriate storing units, and positional information is judged, when the particular data are stored in all the “

n”

units of appropriate storing units.

16. The method of detecting a position according to claim 14, wherein, in step C, a time is calculated at which the inoperative mode is switched to the operation mode next time, when “

m”

-th particular data, where 1≦

“

m”

≦

“

n”

, is received at the last time in the operation mode at step A.

17. The method of detecting a position according to claim 14, wherein, in step C, the operation mode is controlled for receiving at least one “

m”

-th particular data, where 1≦

“

m”

≦

“

n”

, among plural pieces of particular data included in GPS signal.

18. The method of detecting a position according to claim 14, wherein the “

n”

pieces of particular data including the first data to “

n”

-th data transmitted from the satellite in a time series manner are equivalent respectively to the first to fifth sub-frame data.