Method and system for detecting object presence and its duration in a given area

• US 6,915,135 B1
• Filed: 05/15/2001
• Issued: 07/05/2005
• Est. Priority Date: 05/15/2001
• Status: Expired due to Fees

• Current Assignee: Appliance Scientific, Inc. (Ali Holding Srl)
• Original Assignee: Praxis Technology Group Incorporated
• Inventors: Moeller, Eric J., Bauer, Fredrick L., McKee, Philip R.
• Primary Examiner(s): Vo, Nguyen T.
• Assistant Examiner(s): Le, Nhan T.
• Application Number:
  US09/858,265
• Time in Patent Office: 1,512 Days
• Field of Search: 455/456.1, 455/456.5, 455/456.6, 340/539.11, 340/539.13, 340/573.1, 340/573.4, 342/450
• US Class Current: 455/456.6
• CPC Class Codes: G01S 13/78 discriminating between different kinds of targets, e.g. IFF-radar, i.e. identification of friend or foe G01S13/75, G01S13/79 take precedence
• CPC Class Codes: G01S 13/876 Combination of several spaced transponders or reflectors of known location for determining the position of a receiver G01S13/874 takes precedence
• CPC Class Codes: G01S 7/003 Transmission of data between radar, sonar or lidar systems and remote stations
• CPC Class Codes: G08B 13/1427 with transmitter-receiver for distance detection
• CPC Class Codes: G08B 21/0202 Child monitoring systems using a transmitter-receiver system carried by the parent and the child

Abstract

A system (10) for determining a presence, identity, and duration of presence in a given area of an object includes one or more mobile transmitters (12) that periodically send out a beacon signal. A node (14) includes a receiver (16) that receives a beacon signal whenever a mobile transmitter (12) is within a threshold range of the node (14). The node (14) includes a controller (18) that determines a signal strength of each received beacon signal. The controller (18) compares the signal strength of each received beacon signal to a reference signal strength associated with the threshold range in order to determine whether the mobile transmitter (12) was within the desired detection area of the node (14). A base unit (24) sorts received information packets for processing by a base computer (28) in order to determine what mobile transmitter (12) was at what node (14) and for how long.

Claims

1. A system for detecting a presence and its duration in a given area, comprising:

a mobile transmitter operable to periodically send a beacon signal having an unique identification code;

a node at a location within a given area, the node including a receiver operable to receive the beacon signal and the unique identification code from the mobile transmitter in response to the mobile transmitter being within a threshold distance of the node, wherein the node includes a transmitter operable to transmit an information signal to a base unit in response to receipt of the beacon signal, the information signal including information as to the unique identification code of the mobile transmitter and an identification code of the node;

a base unit operable to receive the information signal from the node, the base unit operable to generate reports with respect to a presence and a duration of presence of the mobile transmitter within the threshold distance of the node in response to one or more information signals.

2. The system of claim 1, wherein the base unit includes a base computer operable to process the information signal and generate the reports.

3. A system for detecting a presence and its duration in a given area, comprising:

a mobile transmitter operable to periodically send a beacon signal having an unique identification code;

a node at a location within a given area, the node including a receiver operable to receive the beacon signal and the unique identification code from the mobile transmitter in response to the mobile transmitter being within a threshold distance of the node;

wherein the beacon signal attenuates at a rate of 1/r³ within the desired threshold range, where r is a distance between the mobile transmitter and the node.

4. A method for detecting a presence of an object and its duration within a given area, comprising:

receiving a beacon signal from a mobile transmitter, the beacon signal including a unique identification code;

determining whether the beacon signal was transmitted within a desired threshold range determining whether additional beacon signals having the unique identification code were received from within the desired threshold range;

determining how long a mobile transmitter was within the desired threshold range in response to a number of beacon signals received.

5. The method of claim 4, further comprising:

discarding beacon signals received outside of the desired threshold range.

6. The method of claim 4, wherein the beacon signal attenuates at a rate of 1/r³ within the desired threshold range, where r is a distance of transmission from the mobile transmitter.

7. The method of claim 4, wherein beacon signals are periodically received when transmitted within the desired threshold range.

8. The method of claim 4, further comprising:

transmitting the unique identification code, a signal strength for each beacon signal received, and a number of beacon signals received.

9. The method of claim 4, further comprising:

determining a signal strength of the beacon signal.

10. A transceiver node for determining object presence and its duration in a given area, comprising:

a receiver operable to receive a beacon signal from an object periodically transmitting beacon signals, the beacon signal including a unique identification code;

a controller operable to determine whether the beacon signal was transmitted within a threshold range of the receiver, the controller operable to process additional beacon signals having the unique identification code and received from within the threshold range of the receiver for determination of an amount of time the object was within the desired threshold range.

11. The transceiver node of claim 10, further comprising:

a transmitter operable to transmit an information packet, the information packet including the unique identification code, an identification code of the receiver, the signal strength of each received beacon signal, and a number of beacon signals received.

12. The transceiver node of claim 11, wherein the beacon signal is received and the information packet is transmitted at different frequencies.

13. The transceiver node of claim 10, wherein the desired threshold range is programmably adjustable.

14. The transceiver node of claim 10, wherein the beacon signal is transmitted by a radio frequency transmission technique.

15. A system for detecting a presence of an object and its duration within a given area, comprising:

means for receiving a beacon signal, the beacon signal including a unique identification code;

means for determining whether the beacon signal was transmitted within a desired threshold range in response to the signal strength;

means for determining whether additional beacon signals having the unique identification code were received from within the desired threshold range;

means for determining how long a mobile transmitter was within the desired threshold range in response to a number of beacon signals received.

16. The system of claim 15, further comprising:

means for determining a signal strength of the beacon signal.

17. The system of claim 16, further comprising:

means for transmitting the unique identification code and signal strength of each beacon signal received.

18. The system of claim 16, further comprising:

means for determining a specific proximity of a sender of each beacon signal within the desired threshold range in response to the signal strength.