RF gun barrel detection system

• US 8,890,745 B2
• Filed: 10/27/2011
• Issued: 11/18/2014
• Est. Priority Date: 10/27/2011
• Status: Active Grant

• Current Assignee: Raytheon Company (Rtx Corporation)
• Original Assignee: Raytheon Company (Rtx Corporation)
• Inventors: Wahlquist, Gary Fred, Wu, Kuang-Yuh
• Primary Examiner(s): Sotomayor, John B
• Application Number:
  US13/282,702
• Publication Number:
  US 20130106643A1
• Time in Patent Office: 1,118 Days
• Field of Search: 342/22, 342/27, 342/90, 342/195
• 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 13/887 for detection of concealed objects, e.g. contraband or weapons
• CPC Class Codes: G01S 7/412 based on a comparison between measured values and known or stored values

Abstract

A method of detecting an object includes receiving first reflected radio frequency (RF) signals from a region using an antenna and generating a first backscattering signature of the region from the first reflected RF signals. The method further includes receiving second reflected RF signals from the region subsequent to receiving the first reflected RF signals and generating at least one second backscattering signature of the region from the second reflected RF signals. The method further includes detecting a difference between the first backscattering signature and the second backscattering signature, and providing a warning indication in response to the difference between the first backscattering signature and the second backscattering signature.

Claims

1. A method of detecting an object, the method comprising:

receiving first reflected radio frequency (RF) signals from a region using an antenna;

generating a first backscattering signature of the region from the first reflected RF signals;

receiving second reflected RF signals from the region using the antenna subsequent to receiving the first reflected RF signals;

generating at least one second backscattering signature of the region from the second reflected RF signals;

determining whether the at least one second backscattering signature substantially matches a pre-determined backscattering signature associated with an object of interest from a library of pre-determined backscattering signatures;

receiving third reflected RF signals from the region using the antenna subsequent to receiving the second reflected RF signals;

generating a plurality of third backscattering signatures from the third reflected RF signals;

determining whether the plurality of third backscattering signatures converge over time with respect to the pre-determined backscattering signature;

detecting a difference between the first backscattering signature and the at least one second backscattering signature; and

providing a warning indication in response to the difference between the first backscattering signature and the at least one second backscattering signature.

2. The method of claim 1, wherein the warning indication is a first warning indication, and wherein the method further comprises providing a second warning indication to the user in response to determining that the at least one second backscattering signature substantially matches the pre-determined backscattering signature.

3. The method of claim 2, further comprising:

in response to determining that the at least one second backscattering signature substantially matches the pre-determined backscattering signature, calculating at least one derivative of a difference between the at least one second backscattering signature and the pre-determined backscattering signature.

4. The method of claim 3, wherein the object of interest includes a gun barrel, wherein the at least one derivative includes an average difference that is less than approximately +1.0 dB and greater than approximately −

1.0 dB, and wherein providing the second warning indication further includes providing the second warning indication to the user subsequent to calculating the average difference.

5. The method of claim 3, wherein the object of interest includes a gun barrel, wherein the at least one derivative includes a standard deviation that is less than approximately 3 dB, and wherein providing the second warning indication further includes providing the second warning indication to the user subsequent to calculating the standard deviation.

6. The method of claim 1, further comprising calculating at least one derivative of a difference between the plurality of third backscattering signatures and the pre-determined backscattering signature.

7. The method of claim 6, wherein the at least one derivative includes an average difference, wherein the warning indication is a first warning indication, and wherein the method further comprises:

determining whether the average difference is less than approximately 0.5 dB; and

providing a second warning indication to the user in response to determining that the average difference is less than approximately 0.5 dB.

11. The weapon detection system of claim 1, wherein the warning indication is a first warning indication, and wherein the processor is further configured to provide a second warning indication in response to determining that the at least one second backscattering signature substantially matches the pre-determined backscattering signature.

8. An object detection system, comprising:

an antenna configured to transmit radio frequency (RF) scanning signals and to receive first and second reflected RF signals from a monitored region;

a memory configured to store a pre-determined backscattering signature associated with an object of interest within a library of pre-determined backscattering signatures;

a processor coupled to the antenna and to the memory, the processor being configured to;

generate a first backscattering signature from the first reflected RF signals;

generate at least one second backscattering signature from the second reflected RF signals;

detect a difference between the first backscattering signature and the at least one second backscattering signature;

determine whether the at least one second backscattering signature substantially matches the pre-determined backscattering signature; and

responsive to determining that the at least one second backscattering signature substantially matches the pre-determined backscattering signature, calculate at least one derivative of a difference between the matching backscattering signature and the pre-determined backscattering signature; and

a warning device coupled to the processor and configured to provide a warning indication in response to the difference between the first backscattering signature and the at least one second backscattering signature.

9. The object detection system of claim 8, further comprising a laser coupled to the processor and configured to illuminate at least a portion of the monitored region, wherein the processor is further configured to energize the laser in response to detecting the difference between the first backscattering signature and the at least one second backscattering signature.

10. The object detection system of claim 8, further comprising:

a camera coupled to the processor and configured to capture video images of the monitored region; and

a user display for displaying the video images, the user display being coupled to the camera,

wherein the processor is further configured to control the camera to capture the video images and send the video images to the user display in response to detecting the difference between the first backscattering signature and the at least one second backscattering signature.

12. The weapon detection system of claim 8, wherein the object of interest includes a gun barrel, wherein the at least one derivative includes an average difference that is less than approximately +1.0 db and greater than approximately −

1.0 db, and wherein providing the second warning indication further includes providing the second warning indication subsequent to calculating the average difference.

13. The weapon detection system of claim 8, wherein the object of interest includes a gun barrel, wherein the at least one derivative includes a standard deviation that is less than approximately 3 db, and wherein providing the second warning indication further includes providing the second warning indication subsequent to calculating the standard deviation.

14. A weapon detection system, comprising:

an antenna configured to receive radio frequency (RF) signals including first and second reflected RF signals from a region;

a memory for storing a pre-determined backscattering signature associated with an object of interest from a library of pre-determined backscattering signatures;

a display unit; and

processing means, coupled to the memory and the display unit, and configured to;

generate a first backscattering signature of the region from the first reflected RF signals;

generate at least one second backscattering signature of the region from the second reflected RF signals;

determine whether the at least one second backscattering signature substantially matches the pre-determined backscattering signature;

detect a difference between the first backscattering signature and the at least one second backscattering signature;

provide a first warning indication at the display unit in response to the difference between the first backscattering signature and the at least one second backscattering signature; and

provide a second warning indication at the display unit in response to determining that the at least one second backscattering signature substantially matches the pre-determined backscattering signature.

15. A threat detection system comprising:

a broadband active antenna array configured to transmit radio frequency (RF) scanning signals and to receive first and second reflected RF signals from a monitored region;

a memory configured to store a pre-determined RF backscatter signature of an object of interest in the monitored region;

a processor coupled to the antenna array and to the memory and configured to compute a first RF backscatter signature from the first reflected RF signals, and a second RF backscatter signature from the second reflected RF signals, the processor further configured to determine whether the second RF backscatter signature corresponds to the pre-determined RF backscatter signature of the at least one object of interest, and to detect a different between the first RF backscatter signature and the second RF backscatter signature; and

a warning device coupled to the processor and configured to generate a first threat warning indication responsive to the difference between the first RF backscatter signature and the second RF backscatter signature, and to generate a second threat warning indication responsive to determining that the second RF backscatter signature corresponds to the pre-determined RF backscatter signature.