Vehicle locating unit with improved power management method

• US 7,593,711 B2
• Filed: 05/18/2005
• Issued: 09/22/2009
• Est. Priority Date: 05/18/2005
• Status: Active Grant

• Current Assignee: Calamp Wireless Networks Inc. (CalAmp Corporation)
• Original Assignee: LoJack Operating Company, LP (Solera Holdings Incorporated)
• Inventors: Nguyen, Son, Rhodes, Jesse, Stroud, Ian Christopher, Howe, Timothy David, Cletheroe, Daniel Jonathan Finchley, Smith, Gerard Edward, Watson, Nigel James, Krishna, Sampath, Romano, Frank, Greendale, Steven Walter, Crewe, Philip Grahame, Marsden, Mark
• Primary Examiner(s): Le; Nhan T
• Application Number:
  US11/131,847
• Publication Number:
  US 20060276160A1
• Time in Patent Office: 1,588 Days
• Field of Search: 455/75, 455/76, 455/127.1, 455/127.5, 455/343.1, 455/343.2, 455/343.5, 455/550.1, 455/572, 455/574, 455/67.11, 455/425, 370/311
• US Class Current: 455/343.5
• CPC Class Codes: G01S 13/825 with exchange of information between interrogator and responder
• CPC Class Codes: H04W 52/0245 according to signal strength
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A vehicle locating unit with improved power management. A receiver receives a signal from a network of communication sources. A signal strength monitoring subsystem determines which of the communication sources are transmitting the strongest signals. A power management subsystem is responsive to the signal strength monitoring subsystem and is configured to alternatively enter sleep and wake-up modes, synchronize the wake-up mode to the communication source transmitting the strongest signal, and test the signal strength of at least one additional communication source according to a predefined sequence.

Claims

1. A vehicle locating unit with improved power management, the vehicle locating unit comprising:

a receiver which receives a signal from a network of communication sources;

a signal strength monitoring subsystem for determining which of the communication sources are transmitting the strongest signals; and

a power management subsystem responsive to the signal strength monitoring subsystem and configured to;

alternatively enter sleep and wake-up modes,

synchronize the wake-up mode to the communication source transmitting the strongest signal, and

test the signal strength of at least one additional communication source according to a predefined sequence.

2. The vehicle locating unit of claim 1 in which the power management subsystem is configured to:

test and store the identity of two communication sources with the two strongest signals,

switch to synchronization with any communication source having a signal stronger than the strongest signal of the two stored communication sources, and

store the identity of any communication source with a signal stronger than the signal of any previously stored communication source.

3. The vehicle locating unit of claim 1 in which there are n communication sources each transmitting a signal at a different time every n seconds.

4. The vehicle locating unit of claim 3 in which n is 8.

5. The vehicle locating unit of claim 1 in which the power management system is configured to include a start-up mode wherein all communication sources are tested.

6. The vehicle locating unit of claim 1 in which the power management subsystem is implemented in a microcontroller.

7. The vehicle locating unit of claim 1 in which the power management subsystem is configured to power down the receiver during the sleep mode and to power up the receiver during the wake-up mode.

8. The vehicle locating unit of claim 1 in which the signal strength monitoring subsystem includes a demodulation circuit.

9. The vehicle locating unit of claim 8 in which the demodulation circuit is a component of the receiver.

10. A system comprising:

a receiver which receives a signal from a network of communication sources;

a signal strength monitoring subsystem for determining which of the communication sources are transmitting the strongest signals; and

a power management subsystem responsive to the signal strength monitoring subsystem and configured to;

alternatively enter sleep and wake-up modes,

synchronize the wake-up mode to the communication source transmitting the strongest signal, and

test the signal strength of at least one additional communication source to ensure the wake-up mode is synchronized to the communication source transmitting the strongest signal.

11. A vehicle locating unit with improved power management, the vehicle locating unit comprising:

a receiver which receives a signal from a network of communication sources;

a signal strength monitoring subsystem for determining which of the communication sources are transmitting the strongest signals; and

a power management subsystem responsive to the signal strength monitoring subsystem and configured to;

test and store the identity of two communication sources with the two strongest signals,

alternatively enter sleep and wake-up modes, the wake-up mode synchronized with the communication source transmitting the strongest signal,

test the signal strength of at least one additional communication source according to a predefined sequence,

switch to synchronization with any communication source having a signal stronger than the strongest signal of the two stored communication sources, and

store the identity of any communication source with a signal stronger than the signal of any previously stored communication source.

12. A vehicle locating unit power management system comprising:

a memory; and

a controller configured to;

alternatively output sleep and wake-up mode signals,

store in said memory the identity of at least a first communication source presenting the strongest signal,

test the signal strength of at least one different communication source during the wake-up mode,

synchronize the wake-up mode to the communication source identified in said memory, and

update the memory to store the identity of a different communication source presenting a signal stronger than the first communication source.

13. A vehicle locating unit with improved power management, the vehicle locating unit comprising:

a receiver which receives a signal from a network of communication sources;

a signal strength monitoring subsystem for determining which of the communication sources are transmitting the strongest signals; and

a power management subsystem responsive to the signal strength monitoring subsystem and configured to;

test and store the identity of two communication sources with the two strongest signals,

switch to synchronization with any communication source having a signal stronger than the strongest signal of the two stored communication sources, and

store the identity of any communication source with a signal stronger than the signal of any previously stored communication source.