Systems and methods of alternating transmitter for metal foil detection near moving doors

Patent metadata

Field	Value
Publication number	US-11688272-B2
Application number	US-202117210281-A
Country	US
Kind code	B2
Filing date	Mar 23, 2021
Priority date	Jul 27, 2020
Publication date	Jun 27, 2023
Grant date	Jun 27, 2023

Abstract

A system may include a security controller communicatively coupled with pedestals having a first set of antennas and a second set of antennas spaced from the first set of antennas to form an interrogation zone. The security controller may be configured to alternate transmission and reception of interrogation signals between the first set of antennas and the second set of antennas. The security controller may be configured to determine whether a metal object is detected in the interrogation zone in response to the reception of the interrogation signals by the second set of antennas or by the first set of antennas. The security controller may be configured to generate and send an alarm signal in response to the metal object being detected in the interrogation zone.

First claim

What is claimed is:

1. A security system, comprising:
a plurality of pedestals comprising a first set of antennas and a second set of antennas spaced from the first set of antennas to form an interrogation zone; and
a security controller communicatively coupled with the plurality of pedestals and configured to:
alternate transmission of interrogation signals between the first set of antennas and the second set of antennas;
alternate reception of the interrogation signals between the second set of antennas and the first set of antennas to coordinate with the transmission of the interrogation signals;
determine whether a metal object is detected in the interrogation zone based on comparing reception of the interrogation signals by the second set of antennas to reception of the interrogation signals by the first set of antennas; and
generate and send an alarm signal in response to the metal object being detected in the interrogation zone.

2. The security system of claim 1 , wherein to determine whether the metal object is detected in the interrogation zone, the security controller is further configured to:
determine a difference between signal levels of the interrogation signals at a first antenna of the second set of antennas and a second antenna of the second set of antennas or at a first antenna of the first set of antennas and a second antenna of the first set of antennas;
compare the difference between the signal levels to a threshold; and
determine whether the metal object is detected in the interrogation zone further in response to the difference between the signal levels being greater than the threshold.

3. The security system of claim 2 , wherein the difference between the signal levels is an absolute value of the difference between the signal levels.

4. The security system of claim 2 , wherein the first antenna of the first set of antennas is vertically positioned above the second antenna of the first set of antennas and the first antenna of the second set of antennas is vertically positioned above the second antenna of the second set of antennas.

5. The security system of claim 1 , further comprising:
a plurality of digital potentiometers communicatively coupled with the security controller, the first set of antennas, and the second set of antennas, and configured to null the interrogation signals received by the first set of antennas or the second set of antennas in response to the reception of the interrogation signals via the plurality of digital potentiometers.

6. The security system of claim 5 , wherein the plurality of digital potentiometers may be calibrated to null the interrogation signals a number of times by matching signal levels of the interrogation signals received by the first set of antennas or the second set of antennas.

7. The security system of claim 1 , further comprising:
a first pedestal comprising the first set of antennas; and
a second pedestal comprising the second set of antennas.

8. The security system of claim 1 , further comprising:
a memory storing instructions for controlling the security system, wherein the security controller is one or more processors further communicatively coupled with the memory.

9. A method of controlling a security system comprising a plurality of pedestals with a first set of antennas and a second set of antennas spaced from the first set of antennas to form an interrogation zone, the method comprising:
alternating transmission of interrogation signals between the first set of antennas and the second set of antennas;
alternating reception of the interrogation signals between the second set of antennas and the first set of antennas to coordinate with the transmission of the interrogation signals;
determining whether a metal object is detected in the interrogation zone based on comparing reception of the interrogation signals by the second set of antennas to reception of the interrogation signals by the first set of antennas; and
generating and sending an alarm signal in response to the metal object being detected in the interrogation zone.

10. The method of claim 9 , wherein determining whether the metal object is detected in the interrogation zone,—further comprises:
determining a difference between signal levels of the interrogation signals at a first antenna of the second set of antennas and a second antenna of the second set of antennas or at a first antenna of the first set of antennas and a second antenna of the first set of antennas;
comparing the difference between the signal levels to a threshold; and
determining whether the metal object is detected in the interrogation zone further in response to the difference between the signal levels being greater than the threshold.

11. The method of claim 10 , wherein the difference between the signal levels is an absolute value of the difference between the signal levels.

12. The method of claim 10 , wherein the first antenna of the first set of antennas is vertically positioned above the second antenna of the first set of antennas and the first antenna of the second set of antennas is vertically positioned above the second antenna of the second set of antennas.

13. The method of claim 9 , further comprising:
nulling the interrogation signals received by the first set of antennas or the second set of antennas in response to the reception of the interrogation signals via a plurality of digital potentiometers communicatively coupled with the first set of antennas and the second set of antennas.

14. The method of claim 13 , wherein the plurality of digital potentiometers may be calibrated to null the interrogation signals a number of times by matching signal levels of the interrogation signals received by the first set of antennas or the second set of antennas.

15. The method of claim 9 , wherein the first set of antennas are positioned in a first pedestal, and the second set of antennas are positioned in a second pedestal.

16. A computer-readable medium storing computer executable instructions of controlling a security system, comprising instructions to:
alternate transmission of interrogation signals by a first set of antennas of a plurality of pedestals to a second set of antennas of the plurality of pedestals spaced from the first set of antennas to form an interrogation zone and by the second set of antennas to the first set of antennas;
alternate reception of the interrogation signals between the second set of antennas and the first set of antennas to coordinate with the transmission of the interrogation signals;
determine whether a metal object is detected in the interrogation zone based on comparing reception of the interrogation signals by the second set of antennas to reception of the interrogation signals by the first set of antennas; and
generate and send an alarm signal in response to the metal object being detected in the interrogation zone.

17. The computer-readable medium of claim 16 , wherein to determine whether a metal object is detected in the interrogation zone, the instructions further comprise to:
determine a difference between signal levels of the interrogation signals at a first antenna of the second set of antennas and a second antenna of the second set of antennas or at a first antenna of the first set of antennas and a second antenna of the first set of antennas;
compare the difference between the signal levels to a threshold; and
determine whether the metal object is detected in the interrogation zone further in response to the difference between the signal levels being greater than the threshold.

Assignees

• Sensormatic Electronics Llc

Inventors

• Bergman Adam S
• Allen John A

Classifications

• G08B26/007 Primary

  Wireless interrogation · CPC title

• G08B21/182

  Level alarms, e.g. alarms responsive to variables exceeding a threshold · CPC title

• G08B13/2471 Primary

  Antenna signal processing by receiver or emitter · CPC title

• G08B13/2474

  Antenna or antenna activator geometry, arrangement or layout (loop antennae H01Q1/22) · CPC title

• G08B13/248

  EAS system combined with another detection technology, e.g. dual EAS and video or other presence detection system · CPC title