Method and system for displaying automatically scaled map according to degree of precision of estimated mobile position

• US 20020183927A1
• Filed: 05/29/2002
• Published: 12/05/2002
• Est. Priority Date: 05/29/2001
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: NEC Corporation
• Inventors: Odamura, Satoshi
• Granted Patent: US 6,714,864 B2
• Time in Patent Office: Days
• US Class Current: 701/213
• CPC Class Codes: G01C 21/20 Instruments for performing navigational calculations G01C21/24, G01C21/26 take precedence
• CPC Class Codes: G01S 19/06 employing an initial estimate of the location of the receiver as aiding data or in generating aiding data
• CPC Class Codes: G01S 19/258 relating to the satellite constellation, e.g. almanac, ephemeris data, lists of satellites in view
• CPC Class Codes: G01S 19/42 Determining position
• CPC Class Codes: G01S 5/0027 of actual mobile position, i.e. position determined on mobile

Abstract

The global position of a mobile terminal is estimated from GPS (global positioning system) signals transmitted from a number of GPS satellites and received by the mobile terminal. The degree of precision of the estimated global position is determined and the size, or scale of an area to be displayed is determined according to the degree of precision, and a map of the area of the determined size is generated according to the global position of the mobile terminal, and displayed on the mobile terminal.

Claims

1. A method of displaying a map on a mobile terminal, comprising the steps of:

a) estimating a global position of said mobile terminal from signals transmitted from a plurality of GPS (global positioning system) satellites and received by said mobile terminal,

b) determining a degree of precision of the estimated global position of said mobile terminal;

c) determining a size of an area to be displayed according to said degree of precision;

d) generating a map of said area of said determined size according to said global position of said mobile terminal; and

e) displaying said map on said mobile terminal.

2. The method of claim 1, wherein step (a) comprises the steps of:

receiving, at said mobile terminal, the signals transmitted from said GPS satellites;

receiving, at a GPS system, the signals transmitted from said GPS satellites, producing therefrom supplemental GPS data and transmitting the supplemental GPS data to the mobile terminal;

producing, at said mobile terminal, a precision GPS signal by using the signals of the GPS satellites received at the mobile terminal and said supplemental GPS data from said GPS system; and

determining, at said GPS system, said global position of the mobile terminal from said precision GPS signal.

3. The method of claim 1, wherein step (a) comprises the steps of:

receiving, at said mobile terminal, signals from said plurality of GPS satellites and producing therefrom a precision GPS signal; and

determining, at said mobile terminal, a global position of the mobile terminal.

4. The method of claim 1, wherein step (b) comprises the steps of:

determining constellatory positions of line-of-sight GPS satellites from said precision GPS signal and determining from said constellatory positions a number of equally divided areas of constellation in which said line-of-sight GPS satellites exist; and

determining said degree of precision of the estimated global position from the determined number of said divided areas.

5. The method of claim 1, wherein step (b) comprises the steps of:

determining a number of GPS satellites whose transmissions are higher than a predetermined signal-to-noise ratio; and

determining said degree of precision of the estimated global position from the determined number of GPS satellites.

6. The method of claim 1, wherein step (b) comprises the steps of:

determining constellatory positions of line-of-sight GPS satellites from said precision GPS signal and determining from said constellatory positions a number of equally divided areas of constellation in which said line-of-sight GPS satellites exist;

determining a number of GPS satellites whose transmissions are higher than a predetermined signal-to-noise ratio; and

determining said degree of precision of the GPS signal from a combination of the determined number of said divided areas and the determined number of said GPS satellites.

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

successively receiving, at said GPS station, a plurality of said precision GPS signal from said mobile terminal during a predetermined time interval and determining therefrom initial and subsequent global positions of said mobile terminal;

determining a moving speed of said mobile terminal from said initial and subsequent global positions of the mobile terminal; and

generating, according to said global positions, a map of an area of normal size when the determined moving speed is lower than a predetermined value and a map of an area larger than the normal size when the determined moving speed is higher than said predetermined value.

8. A mobile communication system comprising:

a communications network;

a server connected to the network for determining a global position from received GPS (global positioning system) signals; and

a mobile terminal for receiving GPS signals from GPS satellites and transmitting the received GCS signals to said server station via said communications network to thereby cause said server station to estimate the global position of the mobile terminal,

said server determining a degree of precision of the estimated global position of said mobile terminal and determining the size of an area to be displayed on said mobile terminal according to said degree of precision, generating a map of said area of said determined size according to said global position of said mobile terminal and communicating the generated map to said mobile terminal.

9. The mobile communication system of claim 8, wherein said server determines constellatory positions of line-of-sight GPS satellites from said precision GPS signal and determines from said constellatory positions a number of equally divided areas of constellation in which said line-of-sight GPS satellites exist, and determines said degree of precision of the estimated global position from the determined number of said divided areas.

10. The mobile communication system of claim 8, wherein said server determines a number of GPS satellites whose transmissions are higher than a predetermined signal-to-noise ratio, and determines said degree of precision of the estimated global position from the determined number of GPS satellites.

11. The mobile communication system of claim 8, wherein said server determines constellatory positions of line-of-sight GPS satellites from said precision GPS signal, determines from said constellatory positions a number of equally divided areas of constellation in which said line-of-sight GPS satellites exist, determines a number of GPS satellites whose transmissions are higher than a predetermined signal-to-noise ratio, and determines said degree of precision of the estimated global position from a combination of the determined number of said divided areas and the determined number of said GPS satellites.

12. The mobile communication system of claim 8, wherein said server successively receives a plurality of said precision GPS signal from said mobile terminal during a predetermined time interval and determines therefrom initial and subsequent global positions of said mobile terminal, determines a moving speed of said mobile terminal from said initial and subsequent global positions of the mobile terminal, and generates, according to said global positions, a map of an area of normal size when the determined moving speed is lower than a predetermined value and a map of an area larger than the normal size when the determined moving speed is higher than said predetermined value.

14. The mobile communication system of claim 13, wherein said mobile terminal determines constellatory positions of line-of-sight GPS satellites from said precision GPS signal and determines from said constellatory positions a number of equally divided areas of constellation in which said line-of-sight GPS satellites exist, and determines said degree of precision of the estimated global position from the determined number of said divided areas.

15. The mobile communication system of claim 13, wherein said mobile terminal determines a number of GPS satellites whose transmissions are higher than a predetermined signal-to-noise ratio, and determines said degree of precision of the estimated global position from the determined number of GPS satellites.

16. The mobile communication system of claim 13, wherein said mobile terminal determines constellatory positions of line-of-sight GPS satellites from said precision GPS signal, determines from said constellatory positions a number of equally divided areas of constellation in which said line-of-sight GPS satellites exist, determines a number of GPS satellites whose transmissions are higher than a predetermined signal-to-noise ratio, and determines said degree of precision of the estimated global position from a combination of the determined number of said divided areas and the determined number of said GPS satellites.

13. A mobile communication system comprising:

a communications network;

a mobile terminal for receiving GPS (global positioning system) signals from GPS satellites, estimating a global position of the mobile terminal from the received GPS signals, determining a degree of precision of the estimated global position and determining the size of an area to be displayed on said mobile terminal according to said degree of precision; and

a server for receiving from said mobile terminal information of said global position and said size via said network, generating a map of said area of said determined size according to the received information and communicating the map to said mobile terminal via said network.