TERMINAL DEVICE, POSITIONING METHOD, AND RECORDING MEDIUM

• US 20100141524A1
• Filed: 01/28/2010
• Published: 06/10/2010
• Est. Priority Date: 06/15/2006
• Status: Active Grant

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: NAGAHARA, Mikio, IMAFUKU, Shigeru, HAYASHI, Akifumi, KURATA, Tomoyuki, MIZUOCHI, Shunichi
• Granted Patent: US 8,022,865 B2
• Time in Patent Office: Days
• US Class Current: 342/357.640
• CPC Class Codes: G01S 19/23 Testing, monitoring, correcting or calibrating of receiver elements
• CPC Class Codes: G01S 19/29 carrier including Doppler, related G01S19/246 takes precedence

Abstract

A terminal device includes a plurality of search channel sections which search for a positioning satellite, a candidate reception frequency calculation section which calculates a candidate reception frequency of a first acquisition target satellite by causing the search channel sections to perform the correlation accumulation process for a first accumulation time, a candidate frequency confirmation section which confirms reliability of the candidate reception frequency by causing the search channel sections to perform the correlation accumulation process for a second accumulation time longer than the first accumulation time, a final frequency calculation section which calculates a final frequency by causing the search channel sections to perform the correlation accumulation process for a third accumulation time longer than the second accumulation time, and a first difference calculation section which calculates a difference between an estimated synchronization frequency corresponding to each first acquisition target satellite and the final frequency.

Claims

1. A terminal device which locates a present position based on signals from a plurality of positioning satellites, the terminal device comprising:

a plurality of search channel sections which search for the positioning satellite while changing an accumulation time of a correlation accumulation process for the signal from the positioning satellite;

a first acquisition target satellite determination section which determines at least one first acquisition target satellite as a first acquisition target;

a candidate reception frequency calculation section which calculates a candidate reception frequency of the first acquisition target satellite determined by the first acquisition target satellite determination section by causing the search channel sections to perform the correlation accumulation process using a first accumulation time;

a candidate frequency confirmation section which confirms reliability of the candidate reception frequency calculated by the candidate reception frequency calculation section by causing the search channel sections to perform the correlation accumulation process using a second accumulation time longer than the first accumulation time;

a final frequency calculation section which calculates a final frequency by causing the search channel sections to perform the correlation accumulation process using a third accumulation time longer than the second accumulation time;

a first difference calculation section which calculates a first difference indicating a difference between an estimated synchronization frequency corresponding to the first acquisition target satellite determined by the first acquisition target satellite determination section and the final frequency; and

a necessary-for-positioning satellite acquisition section which acquires the positioning satellite other than the first acquisition target satellite used to calculate the first difference using the first difference calculated by the first difference calculation section.