ES8207351A1 - Dual frequency anti-theft system. - Google Patents

Dual frequency anti-theft system.

Info

Publication number
ES8207351A1
ES8207351A1 ES506117A ES506117A ES8207351A1 ES 8207351 A1 ES8207351 A1 ES 8207351A1 ES 506117 A ES506117 A ES 506117A ES 506117 A ES506117 A ES 506117A ES 8207351 A1 ES8207351 A1 ES 8207351A1
Authority
ES
Spain
Prior art keywords
frequency
frequencies
center frequency
diode
antenna
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
ES506117A
Other languages
Spanish (es)
Other versions
ES506117A0 (en
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
DETERRENT TECH CORP
Original Assignee
DETERRENT TECH CORP
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by DETERRENT TECH CORP filed Critical DETERRENT TECH CORP
Publication of ES8207351A1 publication Critical patent/ES8207351A1/en
Publication of ES506117A0 publication Critical patent/ES506117A0/en
Granted legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B13/00—Burglar, theft or intruder alarms
    • G08B13/22—Electrical actuation
    • G08B13/24—Electrical actuation by interference with electromagnetic field distribution
    • G08B13/2402—Electronic Article Surveillance [EAS], i.e. systems using tags for detecting removal of a tagged item from a secure area, e.g. tags for detecting shoplifting
    • G08B13/2405—Electronic Article Surveillance [EAS], i.e. systems using tags for detecting removal of a tagged item from a secure area, e.g. tags for detecting shoplifting characterised by the tag technology used
    • G08B13/2422—Electronic Article Surveillance [EAS], i.e. systems using tags for detecting removal of a tagged item from a secure area, e.g. tags for detecting shoplifting characterised by the tag technology used using acoustic or microwave tags
    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B13/00—Burglar, theft or intruder alarms
    • G08B13/22—Electrical actuation
    • G08B13/24—Electrical actuation by interference with electromagnetic field distribution
    • G08B13/2402—Electronic Article Surveillance [EAS], i.e. systems using tags for detecting removal of a tagged item from a secure area, e.g. tags for detecting shoplifting
    • G08B13/2465—Aspects related to the EAS system, e.g. system components other than tags
    • G08B13/2468—Antenna in system and the related signal processing
    • G08B13/2471—Antenna signal processing by receiver or emitter

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Automation & Control Theory (AREA)
  • Computer Security & Cryptography (AREA)
  • Electromagnetism (AREA)
  • General Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Burglar Alarm Systems (AREA)

Abstract

An anti-theft tag (34) containing a semiconductor diode (36) connected to a metal antenna loop (38) is configured to receive two distinct radio frequency transmissions. The diode (36) bridges a closed loop at one end of the antenna (38), forming a tank circuit resonant at twice a selected center frequency. A first transmitter (26) generates a tone modulated radio frequency (f) displaced on one side of the center frequency, and a second transmitter (30) generates a continuous wave radio frequency (f) displaced on the other side of the center frequency. Both signals are fed separately to respective dipole radiating antenna strips (18, 19, 20, 21) on opposite sides of a surveillance area. The dipole strips for the different frequencies are at right angles to each other on each side those for the same frequency are at right angles to each other on opposite sides. This produces cross polarized transmission of both frequencies within the area. Diode (36) of tag (34) mixes the two frequencies received by the antenna loop (38), causing the tank circuit to resonate at the sum of the two frequencies (double the center frequency). That resonant frequency is reradiated to receiver antennae (22, 24) on each side for detection by a very narrow band receiver (42) responsive to the sum frequency. The modulating tone is derived from the received signal and processed to trigger an alarm (44) when the detected signal is of sufficient strength and duration.
ES506117A 1980-10-09 1981-10-08 IMPROVEMENTS IN A SYSTEM FOR THE RECOGNITION OF ARTICLES Granted ES506117A0 (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US19557280A 1980-10-09 1980-10-09

Publications (2)

Publication Number Publication Date
ES8207351A1 true ES8207351A1 (en) 1982-09-01
ES506117A0 ES506117A0 (en) 1982-09-01

Family

ID=22721923

Family Applications (1)

Application Number Title Priority Date Filing Date
ES506117A Granted ES506117A0 (en) 1980-10-09 1981-10-08 IMPROVEMENTS IN A SYSTEM FOR THE RECOGNITION OF ARTICLES

Country Status (12)

Country Link
EP (1) EP0062056A4 (en)
JP (1) JPH0353678B2 (en)
AU (1) AU552568B2 (en)
BR (1) BR8108829A (en)
CA (1) CA1190970A (en)
DK (1) DK161172C (en)
ES (1) ES506117A0 (en)
FI (1) FI73532C (en)
IT (1) IT1142881B (en)
NZ (1) NZ198497A (en)
WO (1) WO1982001437A1 (en)
ZA (1) ZA816937B (en)

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0091581B1 (en) * 1982-04-12 1988-05-18 Ici Americas Inc. Crossed beam high frequency anti-theft system
CA1236542A (en) * 1983-08-02 1988-05-10 Harold B. Williams Electronic article surveillance system having microstrip antennas
US5349332A (en) * 1992-10-13 1994-09-20 Sensormatic Electronics Corportion EAS system with requency hopping
US5347280A (en) * 1993-07-02 1994-09-13 Texas Instruments Deutschland Gmbh Frequency diversity transponder arrangement
US5831530A (en) * 1994-12-30 1998-11-03 Lace Effect, Llc Anti-theft vehicle system
US5798693A (en) 1995-06-07 1998-08-25 Engellenner; Thomas J. Electronic locating systems
US8358209B2 (en) * 2005-06-03 2013-01-22 Sensomatic Electronics, LLC Techniques for detecting RFID tags in electronic article surveillance systems using frequency mixing

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NO126975B (en) * 1967-03-30 1973-04-16 John Welsh
US3631484A (en) * 1969-07-30 1971-12-28 Microlab Fxr Harmonic detection system
US3707711A (en) * 1970-04-02 1972-12-26 Peter Harold Cole Electronic surveillance system
US3895368A (en) * 1972-08-09 1975-07-15 Sensormatic Electronics Corp Surveillance system and method utilizing both electrostatic and electromagnetic fields
GB1586069A (en) * 1976-11-15 1981-03-18 Nedap Nv Detection systems
NL7804417A (en) * 1977-04-28 1978-10-31 Parmeko Ltd DETECTION SYSTEM FOR MONITORING THE POSITION OF AN ARTICLE IN A CONTROL ZONE.
US4139844A (en) * 1977-10-07 1979-02-13 Sensormatic Electronics Corporation Surveillance method and system with electromagnetic carrier and plural range limiting signals
ZA7994B (en) * 1978-01-11 1980-01-30 Tag Radionics Ltd Presence sensing system
US4249167A (en) * 1979-06-05 1981-02-03 Magnavox Government And Industrial Electronics Company Apparatus and method for theft detection system having different frequencies

Also Published As

Publication number Publication date
DK161172C (en) 1991-11-25
IT8149451A0 (en) 1981-10-08
FI73532C (en) 1987-10-09
JPS57501550A (en) 1982-08-26
CA1190970A (en) 1985-07-23
AU7721981A (en) 1982-05-11
DK161172B (en) 1991-06-03
AU552568B2 (en) 1986-06-05
WO1982001437A1 (en) 1982-04-29
EP0062056A4 (en) 1985-06-06
EP0062056A1 (en) 1982-10-13
ZA816937B (en) 1982-11-24
JPH0353678B2 (en) 1991-08-15
IT1142881B (en) 1986-10-15
NZ198497A (en) 1985-08-30
FI73532B (en) 1987-06-30
BR8108829A (en) 1982-08-24
DK258082A (en) 1982-06-09
FI821956A0 (en) 1982-06-02
ES506117A0 (en) 1982-09-01

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