System for tracking an article or person

• US 5,708,421 A
• Filed: 08/19/1996
• Issued: 01/13/1998
• Est. Priority Date: 08/19/1996
• Status: Expired due to Term

• Current Assignee: Radio Systems Corporation
• Original Assignee: Radio Systems Corporation
• Inventors: Boyd, Randy D.
• Primary Examiner(s): SWANN III, GLEN R
• Application Number:
  US08/699,399
• Time in Patent Office: 512 Days
• Field of Search: 340/573, 340/539, 340/572, 119/721
• US Class Current: 340/573.1
• CPC Class Codes: G08B 21/0202 Child monitoring systems using a transmitter-receiver system carried by the parent and the child

Abstract

A system for tracking articles or persons comprising a base unit for transmitting a series of ultrasonic signals and an alarm signal, a remote unit, removably attached to the article or person, for receiving the series of ultrasonic signals from the base unit and for transmitting an electromagnetic signal upon receipt of the ultrasonic signal from the base unit, and a monitoring unit for receiving the alarm signal. The base unit further includes an ultrasonic signal generator, an ultrasonic signal transmitter, an electromagnetic signal receiver for receiving the signal from the remote unit, a timer for determining the amount of time from the transmission of the ultrasonic signals to the receipt of the electromagnetic signal from the remote unit, and a transmitter for transmitting an alarm signal to the remote unit and the monitoring unit when the amount of time from the transmission of the ultrasonic signals to the receipt of the electromagnetic signal from the remote unit is greater than a predetermined amount of time.

Claims

1. A system for tracking an article or person, the system comprising:

(a) a base unit for transmitting a series of ultrasonic signals and an alarm signal;

(b) a remote unit, removably attached to the article or person, for receiving the series of ultrasonic signals from the base unit and for transmitting an electromagnetic signal upon receipt of the ultrasonic signal from the base unit; and

(c) a monitoring unit for receiving the alarm signal,

wherein said base unit further includes;

(a1) means for generating the ultrasonic signals,

(a2) means for transmitting the ultrasonic signals,

(a3) means for receiving the electromagnetic signal from the remote unit,

(a4) means for determining the amount of time from the transmission of the ultrasonic signals to the receipt of the electromagnetic signal from the remote unit, and

(a5) means for transmitting an alarm signal to the remote unit and the monitoring unit when the amount of time from the transmission of the ultrasonic signals to the receipt of the electromagnetic signal from the remote unit is greater than a predetermined amount of time,

wherein said receiver further includes;

(b1) at least one receiving microphone for receiving the series of ultrasonic signals from the base unit,

(b2) means for transmitting an electromagnetic signal to the base unit upon receipt of the ultrasonic signal from the base unit,

(b3) means for receiving the alarm signal from the base unit, and

(b4) means for producing an alarm indication upon receipt of the control signal from the base unit, and

wherein the monitoring unit further includes;

(c1) at least one receiving antenna for receiving the alarm signal from the base unit, and

(c2) means for producing an alarm indication upon receipt of the alarm signal.

2. The system of claim 1 wherein said base unit further includes means for modulating the ultrasonic signals, wherein the signals are modulated to produce non-random patterns of ultrasonic energy.

3. The system of claim 2 wherein the ultrasonic signals transmitted by said base unit are amplitude modulated.

4. The system of claim 2 wherein the ultrasonic signals transmitted by said base unit are frequency modulated.

5. The system of claim 2 wherein the ultrasonic signals transmitted by said base unit are modulated in a pulse train having a particular nonrandom pattern.

6. A method for tracking an article or person, the method comprising:

(a) attaching a releasable ultrasonic energy receiver to the article or person;

(b) transmitting a series of ultrasonic signals from a base unit, further including;

(1) generating the ultrasonic signals,

(2) transmitting the series of ultrasonic signals;

(c) receiving the series of ultrasonic signals with the releasable receiver;

(d) transmitting an electromagnetic signal from the releasable receiver to the base unit upon receipt of the ultrasonic signals at the releasable receiver;

(e) receiving the electromagnetic signal from the releasable receiver at the base unit;

(f) determining the difference in time of the transmission of the ultrasonic signals from the base unit and the receipt of the electromagnetic signal from the releasable receiver at the base unit;

(g) transmitting an alarm signal from the base unit to a monitoring unit when the difference in time is greater than a predetermined value; and

(h) producing an alarm indication in the monitoring unit in response to the receipt of the alarm signal from the releasable receiver.

7. The method of claim 6 wherein said transmitting a series of ultrasonic signals further includes modulating the ultrasonic signals, wherein the signals are modulated to produce non-random patterns of ultrasonic energy.

8. The method of claim 7 further comprising amplitude modulating the transmitted ultrasonic signals.

9. The method of claim 7 further comprising frequency modulating the transmitted ultrasonic signals.

10. The method of claim 7 further comprising modulating the transmitted ultrasonic signals in a pulse train having a particular nonrandom pattern.

11. A method for producing an area for the tracking of an article or person wherein the area has a predetermined boundary, the method comprising

(a) transmitting ultrasonic signals from a plurality of speakers;

(b) receiving the ultrasonic signals at a remote unit releasably attached to the article or person;

(c) determining the amount of time from the transmission of the ultrasonic signals, from each of the plurality of speakers, to the reception of the ultrasonic signals at the remote unit;

(d) determining the location of the remote unit, based upon the amount of time from the transmission of the ultrasonic signals, from each of the plurality of speakers, to the reception of the ultrasonic signals at the remote unit, with respect to the location of the predetermined boundary; and

(e) producing an alarm indication in a monitoring unit when the remote unit reaches the boundary.

12. The method of claim 11 wherein the predetermined boundary is predetermined by generating a set of points in a logic unit, each point in the set corresponding to a combination of:

(1) a first difference in time from the transmission of a first set of ultrasonic signals, from a first speaker, and the reception of the first set of ultrasonic signals at the remote unit, and

(2) a second difference in time from the transmission of a second set of ultrasonic signals, from a second speaker, and the reception of the second set of ultrasonic signals at the remote unit,

wherein the first difference in time represents a first distance from the first speaker to the remote unit and the second difference in time represents a second distance from the second speaker to the remote unit, and wherein the combination of the first distance and the second distance represents a unique point on the predetermined boundary.

13. The method of claim 12 wherein the step of determining the location of the remote unit with respect to the location of the predetermined boundary further comprises the steps of:

(1) generating a position point in the logic unit corresponding to a combination of a first difference in time from the transmission of a first set of ultrasonic signals, from a first speaker, and the reception of the first set of ultrasonic signals at the remote unit, and a second difference in time from the transmission of a second set of ultrasonic signals, from a second speaker, and the reception of the second set of ultrasonic signals at the remote unit, wherein the first difference in time represents a first distance from the first speaker to the remote unit and the second difference in time represents a second distance from the second speaker to the remote unit, and wherein the combination of the first distance and the second distance represents the position of the remote unit;

(2) comparing the position point to the set of points in the logic unit; and

(3) determining whether the position point is within the set of points in the logic unit or outside the set of points in the logic unit.

14. The method of claim 13 wherein the step of producing an alarm indication to the article or person when the remote unit reaches the boundary further comprises producing an alarm indication when the position point is outside the set of points in the logic unit.

15. A method for producing an area for the tracking of an article or person wherein the area has a predetermined boundary, the method comprising:

(a) transmitting ultrasonic signals from a plurality of speakers;

(b) generating a set of points in a logic unit, each point in the set corresponding to a combination of;

(1) a first difference in time from the transmission of a first set of ultrasonic signals, from a first speaker, and the reception of the first set of ultrasonic signals at the remote unit, and

(2) a second difference in time from the transmission of a second set of ultrasonic signals, from a second speaker, and the reception of the second set of ultrasonic signals at the remote unit,

wherein the first difference in time represents a first distance from the first speaker to the remote unit and the second difference in time represents a second distance from the second speaker to the remote unit, and wherein the combination of the first distance and the second distance represents a unique point on the predetermined boundary;

(c) receiving the ultrasonic signals at a remote unit releasably attached to the article or person;

(d) determining the amount of time from the transmission of the ultrasonic signals, from each of the plurality of speakers, to the reception of the ultrasonic signals at the remote unit;

(e) determining the location of the remote unit, based upon the amount of time from the transmission of the ultrasonic signals, from each of the plurality of speakers, to the reception of the ultrasonic signals at the remote unit, with respect to the location of the predetermined boundary further including the steps of;

(1) generating a position point in the logic unit corresponding to a combination of a first difference in time from the transmission of a first set of ultrasonic signals, from a first speaker, and the reception of the first set of ultrasonic signals at the remote unit, and a second difference in time from the transmission of a second set of ultrasonic signals, from a second speaker, and the reception of the second set of ultrasonic signals at the remote unit, wherein the first difference in time represents a first distance from the first speaker to the remote unit and the second difference in time represents a second distance from the second speaker to the remote unit, and wherein the combination of the first distance and the second distance represents the position of the remote unit;

(2) comparing the position point to the set of points in the logic unit; and

(3) determining whether the position point is within the set of points in the logic unit or outside the set of points in the logic unit; and

(f) producing an alarm indication in a monitoring unit when the position point is outside the set of points in the logic unit.