Methods and apparatus for adjusting heading direction in a navigation system
A mobile device is described. The mobile device includes an electronic compass that generates compass data corresponding to an orientation of the mobile device relative to true north. A global positioning system (GPS) module receives a GPS signal from multiple satellites. The GPS module determines a heading direction of a vehicle transporting the mobile device relative to true north based on the position data when the vehicle is moving above a threshold velocity. A motion sensor generates motion data corresponding to a motion of the mobile device when the mobile device is moved. A processor adjusts the heading direction of the vehicle relative to true north based on the compass data when the vehicle is moving below the threshold velocity.
1. A mobile device comprising:
an electronic compass including a magnetic sensor, the electronic compass generating compass data corresponding to an orientation of the mobile device relative to true north;
a global positioning system (GPS) module receiving a GPS signal from a plurality of satellites, the GPS module determining a heading direction of a vehicle transporting the mobile device relative to true north based on the GPS signal when the vehicle is moving above a threshold velocity;
a motion sensor generating motion data corresponding to a motion of the mobile device when the mobile device is moving relative to the vehicle; and
a processor operating the mobile device in at least one of a vehicle pointing mode (VPM) and a device orientation mode (DOM) in response to a velocity of the vehicle decreasing below the threshold velocity,
wherein the processor operates the mobile device in the vehicle pointing mode (VPM) when the mobile device is stationary relative to the vehicle, by adjusting the heading direction determined by the GPS module when the vehicle was moving above the threshold velocity based on a change in the compass data since the decrease in the velocity of the vehicle; and
wherein the processor operates the mobile device in the device orientation mode (DOM) when the motion sensor detects a change in orientation of the mobile device relative to the vehicle, by replacing the heading direction determined by the GPS module with the compass data.
2. The mobile device of claim 1 further comprising a display for displaying a route of the mobile device and a pointer overlaid on the route, the direction of the pointer indicating the heading direction of the vehicle relative to true north.
3. The mobile device of claim 2 wherein the processor periodically adjusts the direction of the pointer in response to the compass data.
4. The mobile device of claim 1 wherein the processor is integrated with the GPS module.
5. The mobile device of claim 1 wherein the GPS module outputs National Marine Electronics Association (NMEA) data.
6. The mobile device of claim 1 wherein the GPS module determines the velocity of the vehicle by dividing a change in a position of the mobile device by a change in time.
7. The mobile device of claim 1 further comprising a user interface for instructing the processor to cease adjusting the determined heading direction of the vehicle relative to true north based on the compass data when the vehicle is moving below the threshold velocity.
8. The mobile device of claim 1 wherein the motion sensor comprises at least one of an accelerometer and gyroscope.
9. A method of adjusting heading direction in a mobile device comprising:
generating compass data at an electronic compass including a magnetic sensor, the compass data corresponding to an orientation of the mobile device relative to true north;
receiving a global position system (GPS) signal from a plurality of satellites;
determining a heading direction of a vehicle transporting the mobile device relative to true north based on the GPS signal when the vehicle is moving above a threshold velocity;
generating motion data corresponding to a motion of the mobile device when the mobile device is moved relative to the vehicle; and
operating the mobile device in at least one of a vehicle pointing mode (VPM) and a device orientation mode (DOM) in response to a velocity of the vehicle decreasing below the threshold velocity,
when the mobile device is stationary relative to the vehicle, operating the mobile device in the vehicle pointing mode (VPM) by adjusting the heading direction determined by the GPS module when the vehicle was moving above the threshold velocity based on a change in the compass data since the decrease in the velocity of the vehicle, and
when the motion sensor detects a change in orientation of the mobile device relative to the vehicle, operating the mobile device in the device orientation mode (DOM) by replacing the heading direction determined by the GPS module with the compass data.
10. The method of claim 9 further comprising displaying a route of the vehicle on a display of the mobile device and a pointer overlaid on the route, the direction of the pointer indicating the heading direction of the vehicle relative to true north.
11. The method of claim 10 further comprising periodically adjusting the direction of the pointer in response to the compass data.
12. The method of claim 9 further comprising outputting National Marine Electronics Association (NMEA) data.
13. A mobile device comprising:
a display for displaying a route of the mobile device, the route including a pointer overlaid on the route, a direction of the pointer indicating the heading direction of a vehicle transporting the mobile device and a position of the pointer indicating a position of the vehicle on the route;
an electronic compass including a magnetic sensor, the electronic compass generating compass data corresponding to an orientation of the mobile device relative to true north;
a global positioning system (GPS) module receiving a GPS signal from a plurality of satellites, the GPS module determining a heading direction of a vehicle transporting the mobile device relative to true north based on the GPS signal when the vehicle is moving above a threshold velocity;
a motion sensor generating motion data corresponding to a motion of the mobile device when the mobile device is moving relative to the vehicle; and
a processor operating the mobile device in at least one of a vehicle pointing mode (VPM) and a device orientation mode (DOM) in response to a velocity of the vehicle is decreasing below the threshold velocity,
wherein the processor operates the mobile device in the vehicle pointing mode (VPM) when the mobile device is stationary relative to the vehicle, by adjusting the heading direction determined by the GPS module when the vehicle was moving above the threshold velocity based on a change in the compass data since the decrease in the velocity of the vehicle, and
wherein the processor operates the mobile device in the device orientation mode (DOM) when the motion sensor detects a change in orientation of the mobile device relative to the vehicle, by replacing the heading direction determined by the GPS module with the compass data.
14. The mobile device of claim 13 wherein the processor periodically adjusts the direction of the pointer in response to the compass data.
15. The mobile device of claim 13 wherein the processor is integrated with the GPS module.
16. The mobile device of claim 13 wherein the GPS module outputs National Marine Electronics Association (NMEA) data.
17. The mobile device of claim 13 wherein the motion sensor comprises at least one of an accelerometer and a gyroscope.
18. The mobile device of claim 13 further comprising a user interface for instructing the processor to cease adjusting the determined heading direction of the vehicle relative to true north based on the compass data when the vehicle is moving below the threshold velocity.