Power saving operation in a GPS-based asset tracking unit

• US 7,102,565 B2
• Filed: 04/23/2004
• Issued: 09/05/2006
• Est. Priority Date: 03/12/2004
• Status: Active Grant

• Current Assignee: Asset Intelligence LLC (PowerFleet, Inc.)
• Original Assignee: Transport International Pool Incorporated (General Electric Company)
• Inventors: Jesson, Joseph E.
• Primary Examiner(s): PHAN, DAO LINDA
• Application Number:
  US10/830,520
• Publication Number:
  US 20050200520A1
• Time in Patent Office: 865 Days
• Field of Search: 342/357.06, 342/357.12, 342/357.13, 701/207, 701/213, 701/215
• US Class Current: 342/357.63
• CPC Class Codes: G01S 19/24 Acquisition or tracking or demodulation of signals transmitted by the system synchronisation aspects of direct sequence spread spectrum modulation H04B1/7073
• CPC Class Codes: G01S 19/34 Power consumption

Abstract

A GPS receiver is activated and it is determined whether the GPS receiver has received within a first predetermined attempt period of time a set of GPS signals that is adequate to determine a location of the GPS receiver. If not, the GPS receiver is deactivated for a first delay period of time. The GPS receiver is then activated again and it is determined whether the GPS receiver has received a complete set of GPS signals within a second predetermined attempt period. If not, the GPS receiver is deactivated for a second delay period of time that is longer than the first delay period of time. The GPS receiver is then activated once more and again attempts to acquire a complete set of GPS signals.

Claims

1. An asset tracking unit, comprising:

a GPS (Global Positioning System) receiver configured to selectively receive GPS signals from GPS satellites; and

a controller coupled to the GPS receiver and programmed to;

activate the GPS receiver in response to a predetermined occurrence;

determine whether the GPS receiver has received within a first predetermined attempt period of time a set of GPS signals adequate to determine a location of the asset tracking unit;

if the controller determines that the GPS receiver did not receive the set of the GPS signals within the first predetermined attempt period of time, deactivate the GPS receiver for a first delay period of time;

activate the GPS receiver upon completion of the first delay period of time;

determine whether the GPS receiver has received within a second predetermined attempt period of time, immediately following the first delay period of time, a set of GPS signals adequate to determine the location of the asset tracking unit;

if the controller determines that the GPS receiver did not receive the set of GPS signals within the second predetermined attempt period of time, deactivate the GPS receiver for a second delay period of time that is longer than the first delay period of time; and

activate the GPS receiver upon completion of the second delay period of time.

2. The asset tracking unit of claim 1, wherein the controller is further programmed to:

determine whether the GPS receiver has received within a third predetermined attempt period of time, immediately following the second delay period of time, a set of GPS signals to determine the location of the asset tracking unit;

if the controller determines that the GPS receiver did not receive the set of GPS signals within the third predetermined attempt period of time, deactivate the GPS receiver for a third delay period of time that is longer than the second delay period of time; and

activate the GPS receiver upon completion of the third delay period of time.

3. The asset tracking unit of claim 2, wherein the first delay period is five minutes, the second delay period is ten minutes and the third delay period is 15 minutes.

4. The asset tracking unit of claim 3, wherein each of the first, second and third predetermined attempt periods is five minutes.

5. The asset tracking unit of claim 1, wherein the controller is configured to allow programming based on user input of respective durations of the first, second and third determined attempt periods and of the first and second delay periods.

6. The asset tracking unit of claim 1, wherein the asset tracking unit times the first and second delay periods with a timing capability of the asset tracking unit.

7. The asset tracking unit of claim 1, further comprising:

a housing that supports the GPS receiver and the controller; and

means for securing the housing to a transportation vehicle.

8. The asset tracking unit of claim 1, further comprising:

a message transmitter coupled to the controller and configured to transmit to a gateway a message indicative of a current location of the asset tracking unit.

9. The asset tracking unit of claim 1, wherein the predetermined occurrence is an event in which a trailer unit to which the asset tracking unit is secured is uncoupled from a tractor unit.

10. The asset tracking unit of claim 1, wherein the first and second delay periods have a combined duration of less than one hour.

11. A method of operating a GPS (Global Positioning System) receiver, the method comprising:

activating the GPS receiver in response to a predetermined occurrence;

determining whether the GPS receiver has received within a first predetermined attempt period of time a set of GPS signals adequate to determine a location of the GPS receiver;

if a determination is made that the GPS receiver did not receive the set of the GPS signals within the first predetermined attempt period of time, deactivating the GPS receiver for a first delay period of time;

activating the GPS receiver upon completion of the first delay period of time;

determining whether the GPS receiver has received within a second predetermined attempt period of time, immediately following the first delay period of time, a set of GPS signals adequate to determine the location of the GPS receiver;

if a determination is made that the GPS receiver did not receive the set of GPS signals within the second predetermined attempt period of time, deactivating the GPS receiver for a second delay period of time that is longer than the first delay period of time; and

activating the GPS receiver upon completion of the second delay period of time.

12. The method of claim 11, further comprising:

determining whether the GPS receiver has received within a third predetermined attempt period of time, immediately following the second delay period of time, a set of GPS signals to determine the location of the GPS receiver;

if a determination is made that the GPS receiver did not receive the set of GPS signals within the third predetermined attempt period of time, deactivating the GPS receiver for a third delay period of time that is longer than the second delay period of time; and

activating the GPS receiver upon completion of the third delay period of time.

13. The method of claim 12, wherein the first delay period is five minutes, the second delay period is ten minutes and the third delay period is 15 minutes.

14. The method of claim 13, wherein each of the first, second and third predetermined attempt periods is five minutes.

15. The method of claim 11, further comprising:

transmitting to a gateway a message indicative of a current location of the GPS receiver.

16. The method of claim 11, wherein the first and second delay periods have a combined duration of less than one hour.

17. An asset tracking system, comprising:

a gateway;

a plurality of asset tracking units, each coupled to a respective transportation vehicle and including;

a GPS (Global Positioning System) receiver configured to selectively receive GPS signals from GPS satellites;

a transmitter; and

a controller coupled to the GPS receiver and to the transmitter and programmed to;

activate the GPS receiver in response to a predetermined occurrence;

determine whether the GPS receiver has received within a first predetermined attempt period of time a set of GPS signals adequate to determine a location of the asset tracking unit;

if the controller determines that the GPS receiver did not receive the set of the GPS signals within the first predetermined attempt period of time, deactivate the GPS receiver for a first delay period of time;

activate the GPS receiver upon completion of the first delay period of time;

determine whether the GPS receiver has received within a second predetermined attempt period of time, immediately following the first delay period of time, a set of GPS signals adequate to determine the location of the asset tracking unit;

if the controller determines that the GPS receiver did not receive the set of GPS signals within the second predetermined attempt period of time, deactivate the GPS receiver for a second delay period of time that is longer than the first delay period of time;

activate the GPS receiver upon completion of the second delay period of time; and

if the controller determines that the GPS receiver received the set of GPS signals, control the transmitter so that the transmitter transmits to the gateway a message that indicates a current location of the respective asset tracking unit.

18. The asset tracking system of claim 17, wherein the respective controller of each asset tracking unit is further programmed to:

determine whether the GPS receiver has received within a third predetermined attempt period of time, immediately following the second delay period of time, a set of GPS signals to determine the location of the asset tracking unit;

if the controller determines that the GPS receiver did not receive the set of GPS signals within the third predetermined attempt period of time, deactivate the GPS receiver for a third delay period of time that is longer than the second delay period of time; and

activate the GPS receiver upon completion of the third delay period of time.

19. The asset tracking system of claim 18, wherein the first delay period is five minutes, the second delay period is ten minutes and the third delay period is 15 minutes.