APPARATUS AND METHOD TO CONSERVE POWER IN A PORTABLE GNSS UNIT

• US 20130271314A1
• Filed: 04/13/2012
• Published: 10/17/2013
• Est. Priority Date: 04/13/2012
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Diggelen, Frank van, Mole, Stephen
• Granted Patent: US 9,658,338 B2
• Time in Patent Office: Days
• US Class Current: 342/357.32
• CPC Class Codes: G01C 22/006 Pedometers
• CPC Class Codes: G01S 19/19 Sporting applications
• CPC Class Codes: G01S 19/34 Power consumption
• CPC Class Codes: G01S 19/52 Determining velocity

Abstract

A device is disclosed that is capable of determining its location using high-power with high accuracy, and using low-power with lower accuracy. By coordinating usage between the high power method and the low power, overall power consumption of the device can be significantly reduced without a significant reduction in accuracy. Such high accuracy may be achieved through the use of a GNSS unit, such a GPS receiver. In addition, the low-power alternative may be achieved using an accelerometer, together with software, hardware or firmware for extrapolating a speed based on the force measurements by the accelerometer. In this manner, the GPS receiver can be operated for only a fraction of overall use, primarily to provide adjustment data necessary to calibrate usage of the accelerometer.

Claims

1. A device comprising:

a location calculation module configured to determine a location of the device;

a force measurement module configured to measure an external force exerted on the device;

a calculation module configured to calculate a speed of the device based on one of the location or the external force; and

a power control module configured to operate the location calculation module in a high-power state or a low-power state depending on at least one condition.

2. The device of claim 1, wherein the location calculation module is a GNSS receiver, and

wherein the force measurement module is an accelerometer.

3. The device of claim 1, wherein the location calculation module, when operating in the high-power state, consumes more power than the force measurement module.

4. The device of claim 1, wherein the power control module controls the location calculation module to operate in the low-power state more often than the high-power state.

5. The device of claim 1, wherein the at least one condition includes at least one of whether the location calculation module has been in a current power state for more than a predetermined time interval and whether a fluctuation in the speed calculated by the calculation module exceeds a predetermined threshold.

6. The device of claim 1, wherein when the location calculation module is operating in the low-power state, the calculation module is configured to determine the speed of the device based on a force frequency of the external force and a stored step length.

7. The device of claim 1, wherein the calculation module is configured to calculate a step length of the user when the location calculation module operates in the high-power state, and

wherein the calculation module is configured to calculate the step length based on the external force measured by the force measurement module and the location determined by the location calculation module.

8. The device of claim 7, wherein the calculation module is configured to calculate the speed based on a combination of the external force and the calculated step length when the location calculation module operates in the low-power state, and

wherein the calculation module is configured to calculate the speed based on the location when the location calculation module operates in the high-power state.

9. The device of claim 8, wherein the calculation module is configured to calculate the step length when the calculation module determines that a current speed differs from a previous speed by a predetermined threshold.

10. A method for measuring a speed of a GNSS-enabled device, the method comprising:

receiving force measurements from a force measurement module; and

during a first operation state;

operating a GNSS receiver in a high-power state;

calculating a step length based on the force measurements received from the force measurement module and the locations received from the GNSS receiver;

storing the step length in a memory module; and

calculating the speed based on location information received from the GNSS receiver.

11. The method of claim 10, further comprising:

during a second operation state;

operating the GNSS receiver in a low-power state; and

calculating the speed based on the force measurements received from the force measurement module and the stored step length

12. The method of claim 11, further comprising:

switching from the first operation state to the second operation state when a first predetermined time period has elapsed since the GNSS-enabled device entered the first operation state; and

switching from the second operation state to the first operation state when at least one of;

a second predetermined time period has elapsed since the GNSS-enabled device entered the second operation state; and

the calculated speed has changed from a previously-calculated speed by more than a predetermined threshold.

13. A device, comprising:

a force measurement module configured to measure, as an external force exerted on the device, a step frequency of a user of the device;

a memory module configured to store a step length of the user; and

a processor configured to retrieve the step length from the memory module and to calculate a speed of the device based on the step frequency and the stored step length.

14. The device of claim 13, wherein the step frequency is indicative of whether the user is traveling along a substantially flat path, along an uphill path, or along a downhill path.

15. The device of claim 14, wherein the processor is configured to adjust its speed calculation based on whether the step frequency is indicative of the user traveling along the substantially flat path, along the uphill path, or along the downhill path.

16. The device of claim 14, wherein the force measurement module is configured to measure the external force along each of a plurality of measurement axes.

17. The device of claim 13, wherein the processor is configured to calculate the speed based on the force measured along one of the plurality of measurement axes, and

wherein the processor is configured to adjust its speed calculation based on the force measured along at least another of the plurality of measurement axes.

18. The device of claim 14, further comprising a location calculation module configured to detect a location of the device,

wherein the processor is configured to calculate the speed based on the step frequency and the stored length during a first time period, and

wherein the processor is configured to calculate a second speed based on the location received from the location calculation module during a second time period.

19. The device of claim 18, wherein the processor is configured to determine whether the user is traveling along the substantially flat path, the uphill path, or the downhill path during the second time period based on the calculated second speed and the frequency of the force measured by the force measurement module.

20. The device of claim 18, wherein the processor is configured to determine whether the user is traveling along the substantially flat path, the uphill path, or the downhill path during the second time period by comparing a current force frequency at a current speed to a previous force frequency and a corresponding previous speed.