Method for determining an initial position in a navigation system

• US 20060184324A1
• Filed: 02/14/2006
• Published: 08/17/2006
• Est. Priority Date: 02/16/2005
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Yang, Sung-Chul, Hyun, Moon-Pil, Kim, Jin-Won
• Granted Patent: US 7,577,526 B2
• Time in Patent Office: Days
• US Class Current: 701/213
• CPC Class Codes: G01S 19/22 Multipath-related issues
• CPC Class Codes: G01S 19/26 involving a sensor measurement for aiding acquisition or tracking
• CPC Class Codes: G01S 19/28 Satellite selection
• CPC Class Codes: G01S 19/42 Determining position
• CPC Class Codes: G01S 19/50 whereby the position solution is constrained to lie upon a particular curve or surface, e.g. for locomotives on railway tracks

Abstract

A function for identifying a current position of a user and providing information about a route to a desired destination is implemented. A mobile communication terminal with a navigation system accurately determines an initial position using a global positioning system (GPS) satellite constellation and a GPS signal intensity and provides a personal navigation service with an improved accuracy.

Claims

1. A method for determining an initial position in a navigation system, comprising the steps of:

computing the total number of global positioning system (GPS) satellites from which a received GPS signal intensity greater than a threshold value;

computing the number of GPS satellites located with in at least region of two regions from the total number of the GPS satellites; and

determining an initial position of the navigation system according to a comparison result based on the number of GPS satellites in each of the at least two regions.

2. The method of claim 1, wherein the step of determining the initial position comprises the steps of:

comparing values representing the number of GPS satellites in each of the at least two regions; and

determining that the initial position is located in a region having the greatest value in the comparison result.

3. The method of claim 2, wherein the number of GPS satellites computed for the region having the greatest value is at least 3.

4. The method of claim 1, wherein the step of computing the number of GPS satellites, comprises the steps of:

referring to a map database and dividing an area into two regions with respect to a road'"'"'s centerline;

computing an angle to a road and an azimuth angle to each GPS satellite with respect to due North;

setting a range for each region using the computed road angle;

determining if the computed azimuth angle to each GPS satellite is included in the range for a corresponding region; and

determining that a GPS satellite is located in a given region if the computed azimuth angle for a corresponding GPS satellite is included in the range of a corresponding region for the given region.

5. The method of claim 3, wherein one of the two regions has a range defined by an angle which is greater than the first angle and less than the first angle+180 degrees.

6. The method of claim 4, wherein the step of determining if the computed azimuth angle to each GPS satellite is included in the range for a given region includes determining if the computed azimuth angle of each corresponding GPS satellite is greater than the computed road angle and less than the road angle+180 degrees.

7. The method of claim 1, further comprising the steps of:

estimating a position error using a horizontal dilution of precision (HDOP);

determining if a value of the estimated position error exceeds a distance between the road'"'"'s centerline and a sidewalk; and

measuring a received GPS signal intensity if the estimated position error exceeds the distance between the road'"'"'s centerline and the sidewalk.

8. The method of claim 7, wherein the distance between the roads centerline and the sidewalk is computed on a basis of the number of lanes of the road stored in a map database.