POSITIONING DEVICE, ELECTRONIC INSTRUMENT, AND STORAGE MEDIUM STORING PROGRAM

• US 20090262020A1
• Filed: 06/29/2009
• Published: 10/22/2009
• Est. Priority Date: 10/26/2006
• Status: Active Grant

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: KIMURA, Akira
• Granted Patent: US 7,839,328 B2
• Time in Patent Office: Days
• US Class Current: 342/357.630
• 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 19/29 carrier including Doppler, related G01S19/246 takes precedence
• CPC Class Codes: G01S 19/37 Hardware or software details of the signal processing chain

Abstract

Signals output from two filters included in a filter section 70 and differing in passband are respectively stored in different memories included in a memory section 80, and a positioning process is performed based on the signal stored in the memory. Specifically, the signal strength of a received signal is calculated by a coherent accumulation process and an incoherent accumulation process, and a signal system used for positioning is alternatively switched to a high-sensitivity system S1 or a high-accuracy system S2 as a result of determining whether or not the signal strength is equal to or greater than a threshold value.

Claims

1. (canceled)

2. A positioning device comprising:

a first filter and a second filter, the first filter and the second filter having a variable passband and extracting a signal in a specific frequency band from a signal received from a GPS satellite;

a first storage section that stores a signal output from the first filter;

a second storage section that stores a signal output from the second filter; and

a positioning section that performs a specific positioning process based on the signal stored in the first storage section or the second storage section.

3. The positioning device as defined in claim 2, wherein

a GPS satellite group is assigned to each of the first filter and the second filter under a predetermined condition, and

the passband of each of the first filter and the second filter are set so as to extract a signal received from each GPS satellite that belongs to the corresponding GPS satellite group.

4. The positioning device as defined in claim 3, wherein

the GPS satellite group is assigned to each of the first filter and the second filter based on the angle of elevation of each GPS satellite.

5. The positioning device as defined in claim 3, wherein

the passband of each of the first filter and the second filter are set so as to extract a signal received from each GPS satellite that belongs to the corresponding GPS satellite group based on the signal strength of a signal received from each GPS satellite that belongs to the corresponding GPS satellite group.

6. The positioning device as defined in claim 2, wherein

the first filter, the second filter, the first storage section, and the second storage section are provided in a radio frequency (RF) reception circuit section that receives a signal from a GPS satellite.

7. The positioning device as defined in claim 6, wherein

the first filter and the second filter being digital filters;

and

the RF reception circuit section converts a signal received from a GPS satellite into a digital signal, and causes the digital signal to pass through the first filter or the second filter.

8. The positioning device as defined in claim 6, wherein

the first filter and the second filter are analog filters, and

the RF reception circuit section causes a signal received from a GPS satellite to pass through the first filter, coverts the signal that has passed through the first filter into a digital signal, stores the digital signal converted from the signal that has passed through the first filter in the first storage section, causes a signal received from a GPS satellite to pass through the second filter, converts the signal that has passed through the second filter into a digital signal, and stores the digital signal converted from the signal that has passed through the second filter in the second storage section.

9. An electronic instrument comprising:

a first filter and a second filter, the first filter and the second filter having a variable passband and extracting a signal in a specific frequency band from a signal received from a GPS satellite;

a first storage section that stores a signal output from the first filter;

a second storage section that stores a signal output from the second filter; and

a positioning section that performs a specific positioning process based on the signal stored in the first storage section or the second storage section.

10. A computer-readable storage medium storing a program adapted for a device that includes a first filter and a second filter that have a variable passband and extract a signal in a specific frequency band from a signal received from a GPS satellite, a first storage section that stores a signal output from the first filter, a second storage section that stores a signal output from the second filter, and a processor, the program causing the processor to:

set the passbands of the first filter and the second filter; and

perform a specific positioning process based on the signal stored in the first storage section or the second storage section.