Duty cycle estimation system and method

• US 8,229,518 B2
• Filed: 10/21/2009
• Issued: 07/24/2012
• Est. Priority Date: 10/21/2009
• Status: Active Grant

• Current Assignee: Calamp Wireless Networks Inc. (CalAmp Corporation)
• Original Assignee: LoJack Operating Company, LP (Solera Holdings Incorporated)
• Inventors: Bourque, Stephen
• Primary Examiner(s): Jackson, Blane J
• Application Number:
  US12/589,288
• Publication Number:
  US 20110092163A1
• Time in Patent Office: 1,007 Days
• Field of Search: 455/67.11, 455/572, 455/574
• US Class Current: 455/574
• CPC Class Codes: B60R 25/102 a signal being sent to a remote location, e.g. a radio signal being transmitted to a police station, a security company or the owner
• CPC Class Codes: G01R 31/392 Determining battery ageing or deterioration, e.g. state of health
• CPC Class Codes: H04W 52/0229 where the received signal is a wanted signal
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A method of operating a vehicle locating unit wherein an activation signal is received when the vehicle is stolen and in response to the activation signal, a signal indicating the vehicle has been stolen is transmitted. The receiver is energized for an actual duration N_on periodically to listen for the activation and other signals. Estimating how long the receiver has been on includes incrementing a counter at a count resolution where N_on is typically at least sometimes less than the count resolution. Estimating the total amount of time the receiver was energized is based on a measured on time after it converges with the actual on time.

Claims

1. A method of operating a vehicle locating unit, the method comprising:

receiving an activation signal when the vehicle is stolen;

transmitting, in response to the activation signal, a signal indicating the vehicle has been stolen;

energizing the receiver for an actual duration N_on periodically; and

estimating how long the receiver has been on including;

incrementing a counter at a count resolution where N_on is typically at least sometimes less than the count resolution,

when the receiver is energized for an actual on time N_on and the count does not increment, setting a measured receiver on time to be a first value,

when the receiver is energized for an actual on time N_on and the count does increment, setting a measured receiver on time to be a second value, and

estimating the total amount of time the receiver was energized based on the first and second values when the measured on times converge with the actual on times.

2. The method of claim 1 in which the receiver is energized via a battery, the method further including calculating battery usage based on the estimation.

3. The method of claim 1 in which the first value is 0.

4. The method of claim 1 in which the second value is a function of the number of count elements occurring while the receiver was energized.

5. The method of claim 4 in which the second value is the number of count increments multiplied by the count resolution.

6. A vehicle locating unit comprising:

a transmitter for transmitting a signal indicating the vehicle has been stolen;

a receiver for receiving an activation and other signals;

a battery powering at least the receiver;

a processing subsystem controlling the transmitter to transmit the signal indicating the vehicle has been stolen upon receipt of an activation signal, the processing subsystem configured to;

energize the receiver for an actual duration N_on periodically to save battery power, and

estimate how long the receiver has been on including;

incrementing a counter at a count resolution where N_on is typically at least sometimes less than the count resolution,

when the receiver is energized for an actual on time N_on and the count does not increment, setting a measured receiver on time to be a first value,

when the receiver is energized for an actual on time N_on and the count does increment, setting a measured receiver on time to be a second value, and

estimating the total amount of time the receiver was energized based on the first and second values when the measured on times converge with the actual on times.

7. The vehicle locating unit of claim 6 in which the processing subsystem is further configured to calculate battery usage based on the estimation.

8. The vehicle locating unit of claim 6 in which the second value is the number of count increments occurring while the receiver was energized.

9. The vehicle locating unit of claim 8 in which the second value is a function of the number of count increments multiplied by the count resolution.

10. A method comprising:

powering an electronic device when active via a battery;

energizing the electronic device periodically for an actual duration N_on;

incrementing a counter at a count resolution where N_on is typically at least sometimes less than the count resolution;

when the device is energized for an actual on time N_on and the count does not increment, setting a measured device on time to be a first value;

when the device is energized for an actual on time N_on and the count does increment, setting a measured device on time to be a second value; and

estimating the total amount of time the device was energized based on the first and second values when the measured device on times converge with the actual device on times.

11. The method of claim 10 further including calculating battery usage based on the estimation.

12. The method of claim 10 in which the first value is 0.

13. The method of claim 10 in which the second value is a function of the number of count increments occurring while the device was energized.

14. The method of claim 13 in which the second value is the number of count increments multiplied by the count resolution.

15. A system comprising:

an electronic device periodically activated for an actual duration N_on;

a battery powering said electronic device; and

a power usage estimator subsystem including;

a counter incremented at a count resolution where N_on is typically at least sometimes less than the count resolution,

means for setting a measured device on time based on the number of count increments and the count resolution when the device is energized for an actual on time N_on and the count does increment; and

means for estimating the total amount of time the device was energized based on the measured device on times after said measured device on times converge with the actual device on times.

16. A duty cycle determination method for device having a duty cycle

17. The method of claim 16 in which the device is battery operated, the method further including calculating battery usage based on the estimation.

18. The method of claim 16 in which the first value is 0 and is ignored in the estimation.

19. The method of claim 16 in which the second value is a function of the number of count increments occurring while the device is energized.

20. The method of claim 16 in which the second value is the number of count increments multiplied by the count cycle.