Mobile terminals, methods, and program products for generating a magnetic heading based on position

• US 7,069,145 B2
• Filed: 05/03/2004
• Issued: 06/27/2006
• Est. Priority Date: 05/03/2004
• Status: Expired due to Fees

• Current Assignee: Sony Ericsson Mobile Communications (Sony Group Corp.), Sony Ericsson Mobile Communications USA Incorporated (Sony Group Corp.)
• Original Assignee: Sony Ericsson Mobile Communications USA Incorporated (Sony Group Corp.)
• Inventors: Klinghult, Gunnar, Jendbro, Magnus
• Primary Examiner(s): Zanelli, Michael J.
• Application Number:
  US10/837,837
• Publication Number:
  US 20050246099A1
• Time in Patent Office: 785 Days
• Field of Search: None
• US Class Current: 701/207
• CPC Class Codes: G01C 17/38 Testing, calibrating, or compensating of compasses
• CPC Class Codes: G01C 21/20 Instruments for performing navigational calculations G01C21/24, G01C21/26 take precedence

Abstract

Mobile terminals, methods, and program products for generating a magnetic heading. A geographic position of the mobile terminal is determined. A magnetic field at the mobile terminal is sensed. A magnetic inclination and/or a magnetic declination of the magnetic field is determined based on the determined geographic position. A magnetic heading is determined for the mobile terminal based on the sensed magnetic field and based on the determined magnetic inclination and/or magnetic declination.

Claims

1. A method for generating a magnetic heading for a mobile terminal, comprising:

determining a geographic position of the mobile terminal;

sensing a magnetic field at the mobile terminal;

determining a magnetic inclination and/or a magnetic declination of the magnetic field based on the determined geographic position; and

determining a magnetic heading for the mobile terminal based on the sensed magnetic field while compensating for orientation of the mobile terminal relative to Earth based on the determined magnetic inclination and/or magnetic declination without use of information from sensors that sense orientation of the mobile terminal relative to Earth.

2. The method of claim 1, wherein:

determining a magnetic inclination and/or a magnetic declination comprises determining the magnetic inclination and the magnetic declination of the magnetic field based on the determined geographic position; and

determining a magnetic heading comprises determining the magnetic heading for the mobile terminal based on the sensed magnetic field and based on the determined magnetic inclination and the determined magnetic declination.

3. The method of claim 1, wherein determining a geographic position of the mobile terminal comprises:

receiving satellite signals at the mobile terminal; and

determining the geographic position based on the received satellite signals.

4. The method of claim 1, wherein determining a geographic position of the mobile terminal comprises:

receiving cellular signals at the mobile terminal; and

determining the geographic position based on the received cellular signals.

5. The method of claim 1, wherein determining a geographic position of the mobile terminal comprises triangulating the position of the mobile terminal based on wireless communication signals from a plurality of terrestrial wireless communication signal transmitters.

6. The method of claim 1, wherein determining a geographic position of the mobile terminal comprises receiving the geographic position of the mobile terminal from a wireless network.

7. The method of claim 1, wherein determining a geographic position of the mobile terminal comprises:

receiving at the mobile terminal country code information and/or cell identification information from a wireless network; and

determining the geographic position based on the received country code information and/or cell identification information.

8. The method of claim 1, wherein determining a magnetic inclination and/or a magnetic declination of the magnetic field based on the determined geographic position comprises:

providing in the mobile terminal a database of information on the magnetic inclinations and/or magnetic declinations that are associated with geographic positions; and

determining the magnetic inclination and/or the magnetic declination of the magnetic field for a determined geographic position based on information in the database.

9. The method of claim 1, wherein determining a magnetic inclination and/or a magnetic declination of the magnetic field based on the determined geographic position comprises requesting from a wireless network the magnetic inclination and/or the magnetic declination of the magnetic field based on the determined geographic position.

10. The method of claim 1, wherein determining a magnetic heading for the mobile terminal comprises determining the magnetic heading based on the following equation:

$C=\left[\begin{array}{c}\mathrm{Hx}\\ \mathrm{Hy}\\ \mathrm{Hz}\end{array}\right]·<br><br>{\left[\begin{array}{c}\mathrm{Ho}·<br><br>\mathrm{Cos}<br><br><br><br>\mathrm{\delta <br><br>}·<br><br>\mathrm{Cos}<br><br><br><br>\mathrm{\gamma <br><br>}\\ \mathrm{Ho}·<br><br>\mathrm{Sin}<br><br><br><br>\mathrm{\delta <br><br>}·<br><br>\mathrm{Sin}<br><br><br><br>\mathrm{\gamma <br><br>}\\ \mathrm{Ho}·<br><br>\mathrm{Sin}<br><br><br><br>\mathrm{\delta <br><br>}\end{array}\right]}^{-1},$

wherein C comprises the Direction Cosine Matrix, Hx, Hy and Hz comprise components of the sensed magnetic field, δ

comprises the determined magnetic inclination, and γ

comprises the determined magnetic declination, and wherein Ho comprises an absolute strength of the sensed magnetic field based on the following equation;

Ho=√

{square root over (Hx²+Hy²+Hz²)}.

11. The method of claim 1, wherein determining a magnetic heading for the mobile terminal comprises removing at least some known electronic interference from the sensed magnetic field.

12. A mobile terminal comprising:

a position determination unit that is configured to determine a geographic position of the mobile terminal;

a magnetic field sensor that is configured to sense a magnetic field at the mobile terminal; and

a processor unit that is configured to determine a magnetic inclination andlor a magnetic declination of the magnetic field based on the determined geographic position, and that is configured to determine a magnetic heading for the mobile terminal based on the sensed magnetic field while compensating for orientation of the mobile terminal relative to Earth based on the determined magnetic inclination and/or magnetic declination without use of information from sensors that sense orientation of the mobile terminal relative to Earth.

13. The mobile terminal of claim 12, wherein the processor unit is configured to determine a magnetic inclination and a magnetic declination of the magnetic field based on the determined geographic position, and is configured to determine a magnetic heading for the mobile terminal based on the sensed magnetic field and based on the determined magnetic inclination and magnetic declination.

14. The mobile terminal of claim 12, wherein the processor unit comprises a memory in which a plurality of geographic locations are associated with a plurality of pairs of magnetic inclinations and magnetic declinations.

15. The mobile terminal of claim 12, wherein the processor unit is configured to request from a wireless network the magnetic inclination and/or the magnetic declination of the magnetic field based on the determined geographic position.

16. The mobile terminal of claim 12, wherein the position determination unit is configured to receive satellite signals, and is configured to determine the geographic position of the mobile terminal based on the received satellite signals.

17. The mobile terminal of claim 12, wherein the position determination unit is configured to receive wireless communication signals from a plurality of terrestrial wireless communication signal transmitters, and is configured to triangulate the position of the mobile terminal based on the received wireless communication signals.

18. The mobile terminal of claim 12, wherein the position determination unit is configured to receive the geographic position of the mobile terminal from a wireless network.

19. The mobile terminal of claim 12, wherein the position determination unit is configured to receive country code information and/or cell identification information from a wireless network, and is configured to determine the geographic position of the mobile terminal based on the received country code information and/or cell identification information.

20. The mobile terminal of claim 12, wherein the processor unit is configured to determine the magnetic heading for the mobile terminal based on the following equation:

$C=\left[\begin{array}{c}\mathrm{Hx}\\ \mathrm{Hy}\\ \mathrm{Hz}\end{array}\right]·<br><br>{\left[\begin{array}{c}\mathrm{Ho}·<br><br>\mathrm{Cos}<br><br><br><br>\mathrm{\delta <br><br>}·<br><br>\mathrm{Cos}<br><br><br><br>\mathrm{\gamma <br><br>}\\ \mathrm{Ho}·<br><br>\mathrm{Sin}<br><br><br><br>\mathrm{\delta <br><br>}·<br><br>\mathrm{Sin}<br><br><br><br>\mathrm{\gamma <br><br>}\\ \mathrm{Ho}·<br><br>\mathrm{Sin}<br><br><br><br>\mathrm{\delta <br><br>}\end{array}\right]}^{-1},$

wherein C comprises the Direction Cosine Matrix, Hx, Hy and Hz comprise components of the sensed magnetic field, δ

comprises the determined magnetic inclination, and γ

comprises the determined magnetic declination, and wherein Ho comprises an absolute strength of the sensed magnetic field based on the following equation;

Ho=√

{square root over (Hx²+Hy²+Hz²)}.

21. A program product for generating a magnetic heading for a mobile terminal, the program product comprising code embodied in a processor-readable medium, the code comprising:

code configured to receive a sensed magnetic field;

code configured to determine a magnetic inclination and/or a magnetic declination of the magnetic field based on a geographic position of the mobile terminal; and

code configured to determine a magnetic heading for the mobile terminal based on the sensed magnetic field while compensating for orientation of the mobile terminal relative to Earth based on the determined magnetic inclination and/or the magnetic declination without use of information from sensors that sense orientation of the mobile terminal relative to Earth.

22. The program product of claim 21, further comprising code configured to determine the magnetic heading for the mobile terminal based on the following equation:

$C=\left[\begin{array}{c}\mathrm{Hx}\\ \mathrm{Hy}\\ \mathrm{Hz}\end{array}\right]·<br><br>{\left[\begin{array}{c}\mathrm{Ho}·<br><br>\mathrm{Cos}<br><br><br><br>\mathrm{\delta <br><br>}·<br><br>\mathrm{Cos}<br><br><br><br>\mathrm{\gamma <br><br>}\\ \mathrm{Ho}·<br><br>\mathrm{Sin}<br><br><br><br>\mathrm{\delta <br><br>}·<br><br>\mathrm{Sin}<br><br><br><br>\mathrm{\gamma <br><br>}\\ \mathrm{Ho}·<br><br>\mathrm{Sin}<br><br><br><br>\mathrm{\delta <br><br>}\end{array}\right]}^{-1}$

wherein C comprises the Direction Cosine Matrix, Hx, Hy and Hz comprise the sensed magnetic field, δ

comprises the determined magnetic inclination, and γ

comprises the determined magnetic declination, and wherein Ho comprises an absolute strength of the sensed magnetic field based on the following equation;

Ho=√

{square root over (Hx²+Hy²+Hz²)}.