Apparatus and method for location estimation using power supply voltage levels of signal transmitters

• US 20090102642A1
• Filed: 10/22/2007
• Published: 04/23/2009
• Est. Priority Date: 10/22/2007
• Status: Active Grant

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Pham, Hai D., Huseth, Steve D.
• Granted Patent: US 7,830,250 B2
• Time in Patent Office: Days
• US Class Current: 340/539.130
• CPC Class Codes: G01S 11/06 using intensity measurements
• CPC Class Codes: G01S 5/14 Determining absolute distances from a plurality of spaced points of known location

Abstract

Beacon generators transmit wireless beacon signals for use in tracking an object. Among other things, a wireless beacon signal from a particular beacon generator contains information identifying a power supply voltage associated with that beacon generator. A tracking device associated with the object receives one or more of the beacon signals. The tracking device measures the signal strength of a received beacon signal, and the tracking device identifies the power supply voltage associated with the beacon generator that transmitted the received beacon signal. The tracking device or an external component, such as a control unit, can use the identified signal strength and the identified power supply voltage to determine the location of the object. As a particular example, signal strengths and power supply voltages associated with at least three beacon signals can be used to identify the location of the object.

Claims

1. A method comprising:

identifying a power supply voltage associated with a transmitter of a wireless signal;

identifying a signal strength associated with the wireless signal; and

determining a position of an object using the identified power supply voltage and the identified signal strength.

2. The method of claim 1, further comprising receiving the wireless signal from the transmitter;

wherein identifying the power supply voltage comprises using information contained in the wireless signal; and

wherein identifying the signal strength comprises measuring the signal strength of the wireless signal.

3. The method of claim 2, further comprising identifying a transmit power level associated with transmission of the wireless signal by the transmitter;

and

wherein determining the position of the object comprises using the power supply voltage, the signal strength, and the transmit power level.

4. The method of claim 1, wherein determining the position of the object comprises using a signal strength-to-distance mapping that associates signal strength values and distances values.

5. The method of claim 4, further comprising selecting the signal strength-to-distance mapping from among a plurality of mappings based on the power supply voltage.

6. The method of claim 4, further comprising modifying the signal strength-to-distance mapping based on the power supply voltage.

7. The method of claim 4, further comprising modifying the identified signal strength based on the identified power supply voltage;

wherein determining the position of the object comprises using the modified signal strength and the signal strength-to-distance mapping.

8. The method of claim 7, wherein modifying the identified signal strength comprises adding a compensation value to the identified signal strength, the compensation value based on the identified power supply voltage.

9. The method of claim 1, wherein a tracking device associated with the object determines the location of the object.

10. The method of claim 1, wherein:

a controller determines the location of the object, the controller external to a tracking device associated with the object; and

identifying the power supply voltage and the signal strength comprise receiving information identifying the power supply voltage and the signal strength from the tracking device.

11. The method of claim 1, wherein determining the position of the object comprises using signal strengths of multiple wireless signals and power supply voltages associated with multiple transmitters.

12. An apparatus comprising:

a memory configured to store;

information identifying a power supply voltage associated with a transmitter of a wireless signal; and

information identifying a signal strength associated with the wireless signal; and

a controller configured to determine a position of an object using the identified power supply voltage and the identified signal strength.

13. The apparatus of claim 12, further comprising:

a wireless transceiver configured to receive the wireless signal from the transmitter; and

a signal strength unit configured to measure the signal strength of the wireless signal;

wherein the controller is configured to identify the power supply voltage using information contained in the wireless signal.

14. The apparatus of claim 12, further comprising:

at least one of a wireless transceiver and a wired network interface configured to receive the information identifying the power supply voltage and the information identifying the signal strength.

15. The apparatus of claim 12, wherein:

the memory is further configured to store information identifying a transmit power level associated with transmission of the wireless signal by the transmitter; and

the controller is configured to determine the position of the object using the power supply voltage, the signal strength, and the transmit power level.

16. The apparatus of claim 12, wherein the controller is configured to determine the position of the object using a signal strength-to-distance mapping that associates signal strength values and distances values.

17. The apparatus of claim 16, wherein the controller is further configured to select the signal strength-to-distance mapping from among a plurality of mappings based on the power supply voltage.

18. The apparatus of claim 16, wherein the controller is further configured to modify the signal strength-to-distance mapping based on the power supply voltage.

19. The apparatus of claim 16, wherein:

the controller is further configured to modify the identified signal strength based on the identified power supply voltage; and

the controller is configured to determine the position of the object using the modified signal strength and the signal strength-to-distance mapping.

20. A computer program embodied on a computer readable medium, the computer program comprising computer readable program code for:

identifying a power supply voltage associated with a transmitter of a wireless signal;

identifying a signal strength associated with the wireless signal; and

determining a position of an object using the identified power supply voltage and the identified signal strength.

21. A method comprising:

identifying a power supply voltage associated with a transmitter of a wireless signal; and

transmitting a wireless signal containing information associated with the identified power supply voltage and information associated with a transmit power level of the transmitter for use in tracking a wireless device configured to receive the wireless signal.