Positioning device, electronic instrument, and storage medium storing program

• US 7,839,328 B2
• Filed: 06/29/2009
• Issued: 11/23/2010
• 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
• Primary Examiner(s): Tarcza; Thomas H
• Assistant Examiner(s): LIU, HARRY K
• Application Number:
  US12/493,991
• Publication Number:
  US 20090262020A1
• Time in Patent Office: 512 Days
• Field of Search: 342/357.12, 342/357.25, 375/149
• US Class Current: 342/357.25
• 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. A positioning device comprising:

a first signal system that includes a first filter that has a variable passband, and extracts a signal in a specific frequency band from a signal received from a GPS satellite, and a first storage section that stores a signal output from the first filter;

a second signal system that includes a second filter that has a passband that can be variably set separately from the first filter, and extracts a signal from the signal received from the GPS satellite, and

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 of the first signal system or the second signal system.

2. The positioning device as defined in claim 1, wherein

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

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

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

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

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

the passband of each of the first filter of the first signal system and the second filter of the second signal system 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 the signal received from each GPS satellite that belongs to the corresponding GPS satellite group.

5. The positioning device as defined in claim 1, wherein

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

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

the first filter and the second filter are digital filters;

and

the first signal system and the second signal system being provided in the RF reception circuit section so that the signal received from the GPS satellite is converted into a digital signal, and the digital signal is passed through the first filter or the second filter.

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

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

the first signal system and the second signal system being provided in the RF reception circuit section so that the signal received from the GPS satellite is passed through the first filter, the signal that has passed through the first filter is converted into a digital signal, the digital signal converted from the signal that has passed through the first filter is stored in the first storage section, the signal received from the GPS satellite is passed through the second filter, the signal that has passed through the second filter is converted into a digital signal, and the digital signal converted from the signal that has passed through the second filter is stored in the second storage section.

8. The positioning device as defined in claim 1, wherein

a first passband is set for the first filter;

and

a second passband that differs from the first passband is set for the second filter.

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

the first passband is set to extract a high-accuracy signal from the signal received from the GPS satellite, and

the second passband is set to extract a high-sensitivity signal from the signal received from the GPS satellite.

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

the first passband and the second passband are set to have an inclusion relationship.

11. The positioning device as defined in claim 1, wherein

the positioning section changes a coherent accumulation time corresponding to the first signal system or the second signal system, performs a coherent accumulation process on the signal of the corresponding signal system to acquire the GPS satellite signal, and performs the specific positioning process.

12. An electronic instrument comprising:

a first signal system that includes a first filter that has a variable passband, and extracts a signal in a specific frequency band from a signal received from a GPS satellite, and a first storage section that stores a signal output from the first filter;

a second signal system that includes a second filter that has a passband that can be variably set separately from the first filter, and extracts a signal from the signal received from the GPS satellite, and 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 of the first signal system or the second signal system.

13. A non-transitory computer-readable storage medium storing a program adapted for a device that includes a first signal system that includes a first filter that has a variable passband and exteacts a signal in a specific frequency band from a signal received from a GPS satellite, and a first storage section that stores a signal output from the first filter, a second signal system that includes a second filter that has a passband that can be variably set separately from the first filter, extracts a signal from the signal received from the GPS satellite, and a second storage section that stores a signal output from the second filter, and a processor that can execute a program, 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 of the first signal system or the second signal system.