Position detecting system and method

• US 20060293852A1
• Filed: 03/02/2006
• Published: 12/28/2006
• Est. Priority Date: 03/07/2005
• Status: Abandoned Application

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Tsurumi, Kiyoshi
• Application Number:
  US11/365,807
• Publication Number:
  US 20060293852A1
• Time in Patent Office: Days
• US Class Current: 701/216
• CPC Class Codes: G01C 21/28 with correlation of data from several navigational instruments
• CPC Class Codes: G01S 19/22 Multipath-related issues
• 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

Abstract

In a position detecting system by use of GPS signals, a navigation information retrieving part retrieves reception strength information outputted from a navigation device when a current position of a mobile body is in a region in which a multipath is liable to occur. A reception sensitivity change part changes, based on the reception strength information retrieved by the navigation information retrieving part, a threshold level in a reception sensitivity filter part to a level higher than a normal level, which is a reception strength when a direct wave is received. Thereby, the reception sensitivity of the GPS signals is reduced.

Claims

1. A position detecting system that detects a current position with a combination of GPS positioning and dead-reckoning navigation, the device comprising:

a GPS receiving means that receives a GPS signal from a GPS satellite;

a reception strength determining means that determines whether the received GPS signal of the GPS receiving means has a reception strength higher than a predetermined threshold level;

a positioning calculation means that, when it is determined by the determining means that the GPS signal has a reception strength higher than the predetermined threshold level, performs a positioning calculation based on the GPS signal;

a multipath information storing means that stores multipath information about a region in which a multipath is liable to occur; and

a reception sensitivity change means that, when a current position detected by at least one of the GPS positioning and the dead-reckoning navigation is in the region in which the multipath is liable to occur, changes the predetermined threshold level to a higher level to reduce the reception sensitivity of the GPS signal.

2. The position detecting system according to claim 1,

wherein the multipath information storing means includes, as the multipath information, multipath polygon information indicating a position of the region in which the multipath is liable to occur, and information about the reception strength of the GPS signal affected by a multipath fault in the region, and

wherein the reception sensitivity change means changes the predetermined threshold level based on the information about the reception strength.

3. The position detecting system according to claim 1,

wherein the reception sensitivity change means changes the predetermined threshold level to a higher level as an elevation angle of the GPS satellite is smaller, and changes the predetermined threshold level to a lower level as an elevation angle of the GPS satellite is larger.

4. The position detecting system according to claim 1,

wherein the positioning calculation means detects the current position with a combination of GPS positioning, dead-reckoning navigation and map matching.

5. A method of detecting a current position of a mobile body, comprising:

receiving a GPS signal from a GPS satellite;

calculating a current position by positioning calculations based on the GPS signal;

determining whether the calculated current position is in a region, in which a multipath is liable to occur, based on multipath information stored in advance; and

reducing a reception strength of the GPS signal when the calculated current position is in the region in which the multipath is liable to occur.

6. The position detecting method according to claim 5,

wherein the reception sensitivity is set lower when an elevation angle of the GPS satellite is smaller.