Moving-entity detection

• US 8,779,965 B2
• Filed: 12/17/2010
• Issued: 07/15/2014
• Est. Priority Date: 12/18/2009
• Status: Active Grant

• Current Assignee: L3harris Fuzing and Ordnance Systems Incorporated
• Original Assignee: L-3 Communications CyTerra Corporation (L3Harris Technologies, Inc.)
• Inventors: Sentelle, Christopher Gary, Wright, Donald, Fontan, Felix M., Torres-Rosario, Juan Antonio
• Primary Examiner(s): BYTHROW, PETER M
• Application Number:
  US12/971,387
• Publication Number:
  US 20130113647A1
• Time in Patent Office: 1,306 Days
• Field of Search: 342/22, 342/27, 342/28, 342128-144, 342/175, 342/176, 342/179, 342200-204
• US Class Current: 342/22
• CPC Class Codes: G01S 13/04 Systems determining presence of a target based on relative movement of target G01S13/56
• CPC Class Codes: G01S 13/32 using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated
• CPC Class Codes: G01S 13/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S13/46
• CPC Class Codes: G01S 13/56 for presence detection presence detection using near field arrangements G01V3/00, e.g. G01V3/08, G01V3/12; burglar, theft or intruder alarms with electrical actuation G08B13/22 - G08B13/26
• CPC Class Codes: G01S 13/887 for detection of concealed objects, e.g. contraband or weapons
• CPC Class Codes: G01S 13/888 through wall detection
• CPC Class Codes: G01S 7/4021 of receivers
• CPC Class Codes: G01S 7/414 Discriminating targets with respect to background clutter
• CPC Class Codes: G01V 3/12 operating with electromagnetic waves operating with millimetre waves G01V8/005
• CPC Class Codes: G01V 8/005 operating with millimetre waves, e.g. measuring the black losey radiation

Abstract

A stepped-frequency radar signal is transmitted through a barrier. A transmitter of the stepped-frequency radar is on a first side of the barrier, a first object is on a second side of the barrier, and a second object that is distinct from the first object is on the second side of the barrier. A signal including a reflection of the transmitted signal from the first object and a reflection of the transmitted signal from the second object is sensed. The sensed signal is analyzed to determine that a first detection is associated with the first object and a second detection is associated with a second object.

Claims

1. A method comprising:

transmitting, by a device including one or more processors, a stepped-frequency radar signal through a barrier, wherein a transmitter of the stepped-frequency radar is on a first side of the barrier, a first object is on a second side of the barrier, and a second object that is distinct from the first object is on the second side of the barrier;

sensing, by the device including one or more processors, a signal comprising reflections of the transmitted signal from the first object and reflections of the transmitted signal from the second object, the reflections from the first object having a non-zero Doppler shift and the reflections from the distinct second object having a non-zero Doppler shift, and the reflections from the first and the second objects overlapping to form a cluster of reflections such that the sensed signal appears to represent reflections from a single object; and

analyzing, by the device including one or more processors, the sensed signal to determine that the cluster of reflections represents at least one reflection from the first object and at least one reflection from the distinct second object, and that a first detection is associated with the first object and a second detection is associated with a second object.

2. The method of claim 1, wherein the barrier comprises a wall of a building, and the first object and the second object are in an interior of the building.

3. The method of claim 1, further comprising identifying the first detection and the second detection in the sensed signal.

4. The method of claim 1, wherein the first detection associated with the first object comprises multiple detections, and the second detection associated with the second object comprises multiple detections.

5. The method of claim 1, further comprising displaying the first detection and the second detection.

6. The method of claim 1, further comprising producing a visual representation of the first detection and the second detection.

8. The method of claim 1, wherein the first detection comprises multiple detections and the second detection comprises multiple detections, and wherein determining that the first detection is associated with the first object and the second detection is associated with the second object comprises:

determining, from the sensed signal, at least one parameter for each of the multiple detections of the first detection and the second detection, the parameter being one or more of a range value, a Doppler value, or an angle of arrival,

comparing the determined parameter of one of the multiple detections to the determined parameter of another of the multiple detections, and

determining that the one of the multiple detections and the other of the multiple detections are both associated with the first object based on the comparison.

9. The method of claim 1, wherein the stepped-frequency radar signal is transmitted through the barrier at a first time, and further comprising:

transmitting a second stepped-frequency radar signal through the barrier at a second time;

sensing a second signal comprising a second reflection of the transmitted signal from the first object and a reflection of the transmitted signal from the second object, wherein a position of at least one of the first object or the second object relative to the transmitter is different at the second time than at the first time; and

analyzing the second sensed signal to determine that a third detection is associated with the first object and that a fourth detection is associated with the second object.

10. The method of claim 9, further comprising:

determining, based on the first detection and the third detection, a first track that approximates the motion of the first object relative to the transmitter; and

determining, based on the second detection and the fourth detection, a second track that approximates the motion of the second object relative to the transmitter.

11. The method of claim 10, further comprising:

receiving a fifth detection;

comparing at least one parameter of the fifth detection to at least one detection associated with the first track; and

determining whether the fifth detection is associated with the first track based on the comparison.

12. The method of claim 11, further comprising:

analyzing at least one parameter of the fifth detection, prior to the comparison, to determine whether the fifth detection is a candidate for association with the first track; and

determining whether the fifth detection is associated with the first track only when the fifth detection is a candidate for association.

13. The method of claim 12, wherein determining whether the fifth detection is a candidate for association comprises determining whether the parameter of the fifth detection is within a preset range of values.

14. The method of claim 11, wherein the first object comprises a person, and the motion of the person arises from a portion of the person moving relative to the transmitter between the first time and the second time due to breathing of the person.

15. The method of claim 11, wherein the position of the first object relative to the transmitter is different at the second time than at the first time due to one or more of the motion of the first object from a first position within an interior region defined by the barrier to a second position within the interior region or motion of the transmitter.

19. The method of claim 1, wherein analyzing, by the device including one or more processors, the sensed signal to determine that the cluster of reflections represents at least one reflection from the first object and at least one reflection from the distinct second object, and that the first detection is associated with the first object and the second detection is associated with a second object comprises:

analyzing, based on a cluster validity index, the cluster of reflections to determine an estimate of the existence of the first object and the distinct second object; and

determining from the estimate of the existence of the first object and the distinct second object that the first detection is associated with the first object and the second detection is associated with a second object.

20. The method of claim 1, wherein analyzing, by the device including one or more processors, the sensed signal to determine that cluster of reflections represents at least one reflection from the first object and at least one reflection from the distinct second object, and that the first detection is associated with the first object and the second detection is associated with a second object comprises:

analyzing the cluster of reflections to determine an estimate of the existence of the first object and the distinct second object; and

determining from the estimate of the existence of the first object and the distinct second object that the first detection is associated with the first object and the second detection is associated with a second object.

21. The method of claim 4, wherein determining that the first detection is associated with the first object and the second detection is associated with the second object comprises applying an unsupervised clustering technique to the multiple detections of the first detection and the multiple detections of the second detection.

22. The method of claim 21, wherein the unsupervised clustering technique is fuzzy c-means clustering.

7. A method comprising:

transmitting, by a device including one or more processors, a stepped-frequency radar signal through a barrier, wherein a transmitter of the stepped-frequency radar is on a first side of the barrier, a first object is on a second side of the barrier, and a second object that is distinct from the first object is on the second side of the barrier;

sensing, by the device including one or more processors, a signal comprising reflections of the transmitted signal from the first object and from the second object, the reflections from the first and second objects overlapping such that the sensed signal appears to represent reflections from a single object; and

analyzing, by the device including one or more processors, the sensed signal to determine that the reflections represent at least one reflection from the first object and at least one reflection from the distinct second object, and that a first detection is associated with the first object and a second detection is associated with a second object,

wherein the first detection associated with the first object comprises multiple detections, and the second detection associated with the second object comprises multiple detections, and

wherein determining that the first detection is associated with the first object and the second detection is associated with the second object comprises applying fuzzy c-means clustering to the multiple detections of the first detection and the multiple detections of the second detection.

16. A device comprising:

a transceiver configured to receive and transmit multiple radar signals, each radar signal associated with a frequency, through a barrier and into a region defined by the barrier;

a processor coupled to an electronic storage, the electronic storage storing instructions that, when executed, cause the processor to perform operations comprising;

sensing a signal comprising reflections of the transmitted signals from a first object in the region and reflections of the transmitted signals from a second object in the region, the reflections from the first object having a non-zero Doppler shift and the reflections from the second object having a non-zero Doppler shift, and the reflections from the first and the second objects overlapping to form a cluster of reflections such that the sensed signal appears to represent reflections from a single object; and

analyzing the sensed signal to determine that the cluster of reflections represents at least one reflection from the first object and at least one reflection from the distinct second object, and that a first detection is associated with the first object and a second detection is associated with a second object.

17. The device of claim 16, further comprising an interface configured to provide the first detection and the second detection to a remote system.

18. A system comprising:

a sensor system comprising;

a transceiver configured to receive and transmit multiple radar signals, each signal associated with a frequency through a barrier and into a region defined by the barrier;

a processing system in communication with the sensor system, the processing system comprising;

a processor coupled to an electronic storage, the electronic storage storing instructions that, when executed, cause the processor to perform operations comprising;

sensing a signal comprising reflections of the transmitted signals from a first object in the region and reflections of the transmitted signals from a second object in the region, the reflections from the first object having a non-zero Doppler shift and the reflections from the second object having a non-zero Doppler shift, and the reflections from the first and the second objects overlapping to form a cluster of reflections such that the sensed signal appears to represent reflections from a single object; and

analyzing the sensed signal to determine that the cluster of reflections represents at least one reflection from the first object and at least one reflection from the distinct second object, and that a first detection is associated with the first object and a second detection is associated with a second object; and

a display configured to visually present the first and second detections.