US3868669A - Reduction of false alarms in electronic theft detection systems - Google Patents

Reduction of false alarms in electronic theft detection systems Download PDF

Info

Publication number
US3868669A
US3868669A US351019A US35101973A US3868669A US 3868669 A US3868669 A US 3868669A US 351019 A US351019 A US 351019A US 35101973 A US35101973 A US 35101973A US 3868669 A US3868669 A US 3868669A
Authority
US
United States
Prior art keywords
frequency
alarm
signal
circuits
signals
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 - Lifetime
Application number
US351019A
Other languages
English (en)
Inventor
Arthur J Minasy
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.)
Knogo Corp
Original Assignee
Knogo 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
Priority to NLAANVRAGE7404466,A priority Critical patent/NL161904C/xx
Application filed by Knogo Corp filed Critical Knogo Corp
Priority to US351019A priority patent/US3868669A/en
Priority to CA196,105A priority patent/CA1023034A/en
Priority to GB1430274A priority patent/GB1440398A/en
Priority to AU67407/74A priority patent/AU474729B2/en
Priority to ZA00742089A priority patent/ZA742089B/xx
Priority to NL7404466.A priority patent/NL161904B/xx
Priority to IT50160/74A priority patent/IT1018645B/it
Priority to SE7404939A priority patent/SE397145B/xx
Priority to FR7412855A priority patent/FR2228258B1/fr
Priority to DE2417928A priority patent/DE2417928C3/de
Priority to BE143198A priority patent/BE813708A/xx
Priority to JP49041610A priority patent/JPS5752637B2/ja
Application granted granted Critical
Publication of US3868669A publication Critical patent/US3868669A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

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
    • G08B13/2414—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 inductive 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
    • 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
    • G08B13/2474—Antenna or antenna activator geometry, arrangement or layout

Definitions

  • Cited swept frequency system deactivation signals are pro- UNITED STATES PATENTS prised during the portion of the frequency sweep out- 2,794,974 6/1957 Bagno et a1 340/258 A Side the Particular frequency and the deactivation 3,218,556 11/1965 Chisholm 325/478 mains uring the remaining portion of the frequency 3,465,336 9/1969 Fishbein et a1. 340/258 A sweep past the particular frequency.
  • each of the articles to be protected from theft has a electronic responder circuit attached to it.
  • This circuit may be concealed in a wafer like element which may also serve as a price label or the like for the protected article.
  • the articles are maintained in an enclosure having limited egress and checkpoints are set up at each egress.
  • a transmitter is provided at the checkpoint to transmit an interrogation signal and receiver means are provided to note any response produced by the interaction of a wafer responder circuit with the transmitted signal field in the vicinity of the checkpoint.
  • the wafer responder circuits respond to the transmitted interrogation signal, which is at a first frequency, to produce a response signal at a second frequency.
  • the receiver means are tuned to detect this second frequency.
  • the wafer responder circuits are resonant circuits tuned to resonate at the transmitted interrogation frequency.
  • These wafer responder circuits When these wafer responder circuits are brought into the transmitted interrogation signal field they absorb some of the transmitted energy.
  • the receiver means monitors thetransmitted signal, which changes in amplitude due to this absorbtion.
  • the transmitter of this system produces an output frequency which sweeps cyclically over a given range which includes the resonant .frequency of the wafer responder circuits. This causes a series of responses in the form of impulses which occur at a repetition rate corresponding to the frequency sweep rate.
  • the wafer circuit serves to produce a unique electrical response to the interrogation signal
  • similar responses may be produced by nearby electrical equipment such as switches, motors, relays etc., or by other extraneous or sporadic electrical effects; and in such case a false alarm signal may result.
  • the present invention provides an alternative way to reduce the occurrence of false alarm signals.
  • a separate receiving means is provided; but instead of being responsive to the same frequency signals as the main receiving system but at a different location, the separate receiving system of the present invention responds to different frequency signals at the same location as the main receiving system.
  • the separate receiving means comprises a receiving channel tuned to respond to electrical effects which occur only within a frequency range which does not include the response signal frequencies. Should those effects exceed a predetermined magnitude, the separate receiving channel produces an output which is utilized to deactivate the alarm.
  • the transmitter and the wafer responder circuits are arranged so that the wafer responder circuit produces a series of spaced responses.
  • a gating system is set up in a manner which on one hand permits the main receiving system to function only at the times the spaced responses would occur and which on the other hand permits the separate receiving system to function during the intervening times. Should the output of the main receiving system exceed a predetermined level, it will activate an alarm. However, should the output of the separate receiving system exceed a predetermined amount it will override the effect of the first receiving system and deactivate the alarm.
  • a transmitting system is arranged to transmit an interrogation signal at a frequency which is swept back and forth at a given rate and over a range which includes a predetermined wafer responder circuit response frequency.
  • the wafer responder circuits on the protected articles resonate at the response frequency and change the impedance in the vicinity of the transmitting system during the times that the transmitted frequency sweeps past the response frequency.
  • a wafer responder circuit passes through a check-point in the transmitter antenna field, it causes a series of responses to be produced at a repetition rate corresponding to the transmitter frequency sweep rate.
  • a frequency selective switch is provided.
  • This frequency selective switch is arranged to direct the receiver response into a first or a second channel referred to respectively as a noise channel and a signal channel.
  • the frequency selective switch is tuned to span the wafer responder circuit resonant frequency range and is arranged to open the signal channel when the transmitter frequency passes through that range. Whenever the response level exceeds a predetermined threshold in the signal channel an alarm is activated.
  • the filter switch also opens the noise channel during the remaining portions of each transmitter frequency sweep. Whenever the signal level in the noise channel exceeds a given threshold a deactivation signal is produced which deactivates the alarm for a given length of time.
  • FIG. 1 is a fragmentary perspective-view illustrating a checkpoiritfor article theft detection in which the present invention is embodies
  • FIG. 1 there is shown a doorway separating an enclosure 12 .from an exterior region 14.
  • the doorway lflconstitutes one of a limited number of egress passageways from the enclosure. 12; and accordingly it serves as a checkpoint for ascertaining any unauthorized removal of articles from the enclosure.
  • the doorway 10 is provided with several antenna windings 16', I8 and 20 arranged such that when the windings are energized from a transmitter 22, they establish electromagnetic fields'in the region of the doorway 10. These electromagnetic fields serve as a monitoring means since any object passing through the doorway 10 must also pass through the electromagnetic field.
  • All articles to be protected are provided with a wafer 24 (shown in dotted outline) which encapsulates an electronic responder circuit. When the wafer is brought through the doorway 10, its circuit reacts with the electromagnetic field. This response is detected by a receiving system (not shown which activates an alarm. If an article. has
  • FIG. 2 illustrates in block diagram form, the application of the present-invention to a rebroadcaster type electronic theft detection system such as that shown and described 'inU.S. Pat. No. 3,493,955.
  • a transmitter 26 which energizes a transmitter antenna 28 so that the transmitter antenna continuously emits an electromagnetic field at'a monitoring frequency of, for example, 27.2 megahertz (MHZ).
  • the transmitter antenna 28 may comprise one or more of the windings 16,18 and 20 (FIG. 1) so that the electromagnetic field fills the region of the doorway 10.
  • a responder circuit 30, which may be encapsulated in the wafer 24 of FIG. I, is configured to respond to the 27.2 MHZ field and to emit a response signal at a frequency of between 5.1 and 5.9 MHZ, for example.
  • the responder circuit output signals are intercepted by a receiver antenna 32; and they are detected and amplified in a receiver 34.
  • the receiver antenna 34 may also comprise a winding at the doorway 10 (FIG. 1).
  • the output of the receiver 34 passes through a broad band amplifier 36; and from there the detected signals pass'along two channels.
  • the first channel includes a signal filter 38 which is relatively sharply tuned to the output frequency of the responder circuit 30.
  • the output of the signal filter 38 passes to a threshold detector 40 which, upon receipt of a signal of a predetermined magnitude, generates an alarm actuation signal.
  • the alarm actuation signal from the threshold detector passes through a normally open gate circuit 42 to actuate an alarm 44.
  • the alarm 44 may be any audio or visual type indicator means well known in the art.
  • the second channel of the receiver system includes a noise filter 46 which is tuned to pass signals whose frequency components do not lie within the selected signal range, i.e., between 5.1 and 5.9 MHZ.
  • the output of the noise filter is applied to a threshold detector 38.
  • the threshold detector is set to respond to a predetermined noise level and, upon the occurrence of such noise level, to apply a signal to an inhibit terminal 50 of the normally open gate circuit 42.
  • wafers 24 (FIG. I) which contain responder circuits 30 capable of emitting an electromagnetic signal of between 5.1 and 5.9 MHZ when energized by an electromagnetic field at 27.2 MHZ.
  • responder circuits 30 capable of emitting an electromagnetic signal of between 5.1 and 5.9 MHZ when energized by an electromagnetic field at 27.2 MHZ.
  • the present invention is based inpart on the discovery that sporadic and extraneous electrical disturbancesoccur over a rather broad frequency band substantially greater than the selected response signal frequency.
  • sporadic electrical disturbances may produce electromagnetic fields inthe vicinity of the doorway), within the 5.l to 5.9 MHZ response frequency range, those same disturbances will also produce other electromagnetic fulls at frequencies both above and below the response frequency range.
  • FIG. 3 shows in block diagram form, a modified version of the present invention as applied to an electronic theft detection system of the type shown and described in U.S. Pat. No. 3,500,373.
  • the theft detection system includes sweep generator 60 capable of producing a repetitive output sweep, for example a sine wave voltage whose amplitude varies at a frequency of 300 cycles per second.
  • the sweep generator output is applied to a tunable transmitter oscillator 62 which, in response to the signals from the sweep generator 60, produces an output frequency which shifts, for example, from 1.95 to 2.05 MHZ at a 300 cycle per second rate.
  • This varying frequency output is applied to a transmitter amplifier 64 where it is amplified and then applied to a transmitter antenna 66.
  • This transmitter antenna may comprise one or more of the windings 16, 18 and 20 arranged in the doorway I0 of FIG. 1.
  • the antenna 66 produces an electromagnetic field in the vicinity of the doorway which varies in frequency between I95 and 2.05, MHZ at a 300 cycle per second rate.
  • a responder 68 which may be encapsulated within the wafer 24 of FIG. 1, comprises a resonant circuit, such as shown in the aforementioned U.S. Pat. No. 3,500,373. This circuit is tuned to resonante at some fixed frequency between 1,95 and 2.05 MHZ. More specifically, in the present embodiment, the responder circuit is tuned to resonate at 2.00 MHZ.
  • a receiver 70 is connected to a point between the transmitter amplifier 64 and the antenna 66.
  • the output of the receiver 70 is applied to a threshold detector 72, and its output in turn is connected in parallel to a noise gate circuit 74 and to a signal gate circuit 76.
  • the output of the signal gate circuit 76 is connected through a time constant circuit 78 to an alarm 80.
  • the vicinity of the doorway is filled with a high frequency electromagnetic field whose frequency is swept continuously at a 300 cycle per second rate back and forth over a frequency range which includes the resonant frequency of the responder circuit 68.
  • This frequency sweep is illustrated by a curve (a) in FIG. 4.
  • the resonant frequency of the responder circuits 68 which is indicated by a cross hatched strip (b), is chosen to be near the middle of the frequency range.
  • the width of the strip (b) depends upon the Q of the resonant circuits 68, that is, upon the sharpness with which they can be tuned.
  • the impedance presented to the antenna 66 decreases and a greater amount of energy flows out the antenna. Because of this, the amount of transmitter energy presented to the receiver 70 decreases. This phenomenon is experienced twice during each cycle of transmitter frequency sweep, i.e., at 600 times per second.
  • the receiver circuits are designed, as described in U.S. Pat. No. 3,500,373, to respond to the occurrence of energy decreases incident on the receiver at 600 times per second, and to supply a signal to the threshold detector 72 when this occurs. Signals from the threshold detector 72 pass through the signal gate circuit 76, the time constant circuit 78 and activate the alarm 80.
  • the remainder of the system of FIG. 3 is designed to disable the actuation of the alarm 80 whenever spurious electromagnetic or electrical disturbances occur, which otherwise might be interpreted by the receiver 70 and the threshold detector 72 as a responder circuit 68 passing through the field of the antenna 66.
  • the disabling portion of the system of FIG. 3 includes a sharply tuned oscillator 82 which is tuned to a frequency of 1.5 MHZ.
  • the output of this oscillator is ap plied to a mixer 84 along with output signals from the tunable transmitter oscillator 62. These signals, when mixed in the mixer 84, produce an output signal which varies between 450 and 550 KHZ (kilohertz) at a 300 cycles per second rate.
  • the mixer output is applied to i output terminal 92 which are alternately energized.
  • the noise gate actuation output terminal 92 of the monostable multivibrator 88 is energized. However, whenever the output of the mixer 84 reaches a frequency approaching a frequency corresponding to that of the responder circuit 68, the switching filter 86 produces an output causing the monostable multivibrator 88 to deenergize the noise gate actuation terminal 92 and to energize the signal gate actuation terminal 90. Since the switching filter 86 is tuned to have an equivalent band pass range (0) which is slightly greater than the responder circuit response frequency range (b), the switching filter 86 will operate to trigger the monostable multivibrator whenever the antenna frequency approaches the responder circuit resonant frequency in both directions of the antenna frequency sweep, irrespective of whether the antenna frequency is increasing or decreasing.
  • the monostable multivibrator 88 reverts back to its normal state, i.e., with the noise gate actuation output terminal 92 energized and the signal gate actuation output terminal 90 deenergized, after a predetermined length of time following each output from the switching filter 86.
  • This predetermined length of time is slightly longer than the length of time required for the antenna frequency sweep to circuit 68. That is, the monostable multivibrator 88 remains energized over a period of time which straddles the period during which the antenna frequency sweeps across the resonant frequency of the'responder circuits 68. This energization of the monostable multivibrator 88 is illustrated by a curve (d) in FIG. 4.
  • the monostable multivibrator 88 is switched to its non-stable state at different transmitter frequencies depending upon whether the transmitter frequency is increasing or decreasing. This is made possible by thetuning of the switch filter 86. This tuning is broader than that of the responder circuits 68; and it produces a switching signal at the multivibrator 88 just before the antenna frequency reaches the resonant frequency of the responder circuits 68.
  • the ' gate circuit 74 is connected through a signal sustaining circuit 94 to an inhibit terminal 96 of the signal gate circuit 76.
  • the signal sustaining circuit 94 is constructed to cause outputs from the noise gate circuit 74 to remain on the inhibit terminal 96 of the signal gate circuit 76 for a predetermined length of time (e.g., 0.1 seconds), which is substantially in excess of the frequency sweep period of the transmitter. This allows time for any spurious interference to terminate before the system reverts to normal operation.
  • the tunable transmitter oscillator 62 energizes the antenna 66 so that an electromagnetic field is emitted from the antenna 66 into the vicinity of the doorway 10 (FIG. 1).
  • the frequency of this electromagnetic field is continuously varied by the action of the sweep generator 60 so that the antenna field undergoes successivefrequencysweeps between 1.95 and 2.05 MHZ circuit 68 passes through the doorway 10 (FIG. 1) and encounters the field of the antenna 66, the responder circuit will resonate each time the frequency of the antenna field passes through 2.00 MHZ. Since this happens twice during each frequency sweep, a resonant response is generated at the rate of 600 responses per second.
  • the nature of these resonant responses is such that they produce a decrease in antenna output impedance and a corresponding reduction of energy applied to the receiver 70. These decreases in energy are detected by the receiver 70; and its filter configuration is such as to select those ener'gy decreases which occur at the 600 responses per second rate. When this occurs, the receiver 70 produces an output which is applied to the threshold detector 72 and its output in turn is applied to the noise gate circuit and the signal gate circuit 74 and 76 respectively. In the event that the output from the receiver 70 occurs while the anetnna 66 is emitting a frequency within the range (0) of FIG.
  • the receiver causes an output to pass through the threshold detector 72, when the antenna 66 is transmitting outside the range (c) of FIG. 4, then the switching filter will not have caused the monostable multivibrator 88 to energize its signal gate actuation output terminal 90. Instead, the noise gate actuation output terminal 92 of the monstable multivibrator 88 remains energized. Accordingly, the-signal gate 76 remains closed; and the receiver output, which passes through the threshold detector 72, is stopped at the signal gate circuit 76 and does not actuate the alarm 80. Thus, even though a resonant circuit may be present in the antenna field, it will not cause a false alarm if it produces any resonant response outside the preselected resonant frequency range of the responder circuits 68.
  • the system of FIG. 3 provides additional protection in that it uses information obtained during the portion of the frequency sweep outside the preselected responder circuit resonant frequency range to control its operation when the transmitter frequency subsequently reaches the preselected resonant frequency of the responder circuits.
  • the system will, for a predetermined length of time, prevent any alarm actuation even from subsequent responses which do occur within the resonant frequency range. This protects against false alarms from objects which pass through the antenna field and which have an assortment of electrical characteristics producing resonant responses in several frequency ranges including the resonant range of the responder circuits 68.
  • the noise gate circuit 74 in an open condition.
  • the noise gate cir'cuit-74 applies a signal through the signal sustaining circuit 94 to the inhibit terminal 96 of the signal gate circuit 76.
  • the resulting switching of the monostable multivibrator 88 which. opens the signal gate circuit 76 is rendered ineffective because of the continued'presence of an inhibit signal at the'inhibit terminals 96 of the gate circuit 76.
  • This maintains the signal gate circuit 76 is closed for a predetermined length of time (e.g., 0.1 seconds), which is well is excess of the transmitter frequency sweep period. In most instances the sporadic electrical disturbance will have terminated. On the other hand, if the sporadic electrical disturbance should continue. the noise gate circuit 74 will be allowed to produce an inhibit signal gate circuit 76 on the next subsequent transmitter sweep.
  • the present invention provides protection from false alarms based upon active detection in frequency ranges out- 9 side the frequency range of the various responder devices.
  • a system for detecting the unauthorized passage of articles through a checkpoint comprising a transmitter operative to transmit an interrogation signal which varies in frequency, responder circuits mounted on articles whose unauthorized passage is to be detected, said responder circuits being operative to produce a predetermined change in the electromagnetic field conditions in the vicinity of said checkpoint in response to the incidence on said circuits of said interrogation signal within a given frequency range, receiver means operative in response to said predetermined change to produce an alarm actuating signal, alarm means responsive to said actuating signal to produce an alarm indication and means operative to prevent alarm actuation while said interrogation signal is outside said given frequency range.
  • responder circuits include energy absorbing resonant circuits and wherein said receiver means is connected to respond to energy level changes in the vicinity of said checkpoint caused by the absorption of power in a responder circuit passing through the checkpoint.
  • said means operative to prevent alarm actuation comprises a gate circuit associated with said receiver and arranged in the path of said alarm actuating signal, a frequency sensitive switch connected to receive transmitted interrogation signals and to produce switching signals to open said gate circuit when said interrogation signals are within said given frequency range and to close said gate circuit where said interrogation signals are outside said given frequency range.
  • a system for detecting the unauthorized passage of articles through a checkpoint comprising a transmitter operative to transmit an interrogation signal which varies in frequency, responder circuits mounted on articles whose unauthorized passage is to be detected, said responder circuits being operative to produce a predetermined change in the electromagnetic field conditions in the vicinity of said checkpoint in response to the incidence on said circuits of said interrogation signal within a given frequency range, receiver means operative in response to said predetermined change to produce an alarm actuating signal, alarm means responsive to said actuating signal to produce an alarm indication and means associated with said receiver means for producing alarm inhibit signals in response to said predetermined change which occurs while said interrogation signal is outside said given frequency range and means responsive to the occurance of said alarm inhibit signals for inhibiting alarm indications when said interrogation signal subsequently passes through said given frequency range.
  • responder circuits include energy absorbing resonant circuits and wherein said receiver means is connected to respond to energy level changes in the vicinity of said checkpoint caused by the absorption of power in a responder circuit passing through the checkpoint.
  • said means associated with said receiver means comprises first and second gate circuits each connected to receive signals from said receiver means, one of said gate circuits being connected to permit signals passing therethrough to produce an alarm indication, the other gate circuit beingconnected to permit signals passing therethrough to override any opening of said, one gate circuit for a predetermined length of time and a frequency sensitive switch connected to receive transmitted interrogation signals and to produce switching signals to open said one gate when said interrogation signals are within said given frequency range and to open said other gate when said interrogation signals are outside saidgiven frequency range.
  • said frequency sensitive switch includes a multivibrator having two output terminals which are alternately energized and which are connected, respectively, to control terminals of said first and second gate circuits.
  • a system according to claim 10 wherein said transmitter is operative to vary the frequency of said interrogation signal cyclically at a given rate and wherein said signal sustaining circuit has a duration in excess of the cyclic period of frequency variation of said interrogation signal.

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Signal Processing (AREA)
  • Automation & Control Theory (AREA)
  • Computer Security & Cryptography (AREA)
  • Electromagnetism (AREA)
  • General Physics & Mathematics (AREA)
  • Burglar Alarm Systems (AREA)
  • Geophysics And Detection Of Objects (AREA)
US351019A 1973-04-13 1973-04-13 Reduction of false alarms in electronic theft detection systems Expired - Lifetime US3868669A (en)

Priority Applications (13)

Application Number Priority Date Filing Date Title
NLAANVRAGE7404466,A NL161904C (nl) 1973-04-13 Diefstal-detectiestelsel.
US351019A US3868669A (en) 1973-04-13 1973-04-13 Reduction of false alarms in electronic theft detection systems
CA196,105A CA1023034A (en) 1973-04-13 1974-03-27 Reduction of false alarms in electronic theft detection systems
AU67407/74A AU474729B2 (en) 1973-04-13 1974-04-01 Method and apparatus for reducing the occurred of false alarms in electronic theft detection systems
GB1430274A GB1440398A (en) 1973-04-13 1974-04-01 Reuduction of false alarms in electronic theft-detection systems
NL7404466.A NL161904B (nl) 1973-04-13 1974-04-02 Diefstal-detectiestelsel.
ZA00742089A ZA742089B (en) 1973-04-13 1974-04-02 Reduction of false alarms in electronic theft detection systems
IT50160/74A IT1018645B (it) 1973-04-13 1974-04-05 Sistema di avvertimento caratteriz zato da allarmi falsi e minimi
SE7404939A SE397145B (sv) 1973-04-13 1974-04-10 Sett och anordning for att reducera antalet falska alarm i ett elektroniskt skolddetektorsystem
FR7412855A FR2228258B1 (de) 1973-04-13 1974-04-11
DE2417928A DE2417928C3 (de) 1973-04-13 1974-04-11 Verfahren und Vorrichtung zur Verringerung von Fehlaiarmen bei Diebstahldetektionssystemen
BE143198A BE813708A (fr) 1973-04-13 1974-04-12 Procede et dispositif de reduction des fausses alarmes dans les systemes electroniques de protection contre le vol
JP49041610A JPS5752637B2 (de) 1973-04-13 1974-04-13

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US351019A US3868669A (en) 1973-04-13 1973-04-13 Reduction of false alarms in electronic theft detection systems

Publications (1)

Publication Number Publication Date
US3868669A true US3868669A (en) 1975-02-25

Family

ID=23379246

Family Applications (1)

Application Number Title Priority Date Filing Date
US351019A Expired - Lifetime US3868669A (en) 1973-04-13 1973-04-13 Reduction of false alarms in electronic theft detection systems

Country Status (12)

Country Link
US (1) US3868669A (de)
JP (1) JPS5752637B2 (de)
AU (1) AU474729B2 (de)
BE (1) BE813708A (de)
CA (1) CA1023034A (de)
DE (1) DE2417928C3 (de)
FR (1) FR2228258B1 (de)
GB (1) GB1440398A (de)
IT (1) IT1018645B (de)
NL (2) NL161904B (de)
SE (1) SE397145B (de)
ZA (1) ZA742089B (de)

Cited By (30)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4016553A (en) * 1975-06-27 1977-04-05 Knogo Corporation Article detection system with near field electromagnetic wave control
US4045778A (en) * 1976-02-23 1977-08-30 Wagner Electric Corporation Dual channel wide-band frequency modulated keyable control circuit and keying circuit therefor
US4063230A (en) * 1975-06-12 1977-12-13 The Magnavox Company Balanced field theft detection system
US4095214A (en) * 1976-06-17 1978-06-13 Knogo Corporation Electronic monitoring system and responder device
DE2725169A1 (de) * 1977-03-14 1978-09-21 Lichtblau G J Unterdrueckungsschaltung fuer schwebungsfrequenzstoerungen
US4135184A (en) * 1977-08-31 1979-01-16 Knogo Corporation Electronic theft detection system for monitoring wide passageways
FR2398357A1 (fr) * 1977-07-19 1979-02-16 Nedap Nv Dispositif de detection electromagnetique
EP0020062A1 (de) * 1979-05-18 1980-12-10 Parmeko Limited Verfahren und Überwachungssystem zur Feststellung der Anwesenheit eines Empfängers-Rücksenders für elektromagnetische Signale
US4260983A (en) * 1978-01-11 1981-04-07 Tag Radionics Limited Presence sensing detector and system for detecting a receiver/transmitter device affixed to an article
US4281321A (en) * 1980-06-09 1981-07-28 Sensormatic Electronics Corporation Surveillance system employing a floor mat radiator
FR2489001A1 (fr) * 1980-08-21 1982-02-26 Knogo Corp Procede et dispositif de detection electronique de vol d'articles
EP0100128A1 (de) * 1982-07-21 1984-02-08 N.V. Nederlandsche Apparatenfabriek NEDAP Absorbierungsdetektoranlage
US4481428A (en) * 1981-05-19 1984-11-06 Security Tag Systems, Inc. Batteryless, portable, frequency divider useful as a transponder of electromagnetic radiation
US4532511A (en) * 1979-10-12 1985-07-30 Lemelson Jerome H Automatic vehicle identification system and method
US4623877A (en) 1983-06-30 1986-11-18 Knogo Corporation Method and apparatus for detection of targets in an interrogation zone
EP0242901A1 (de) * 1986-03-24 1987-10-28 N.V. Nederlandsche Apparatenfabriek NEDAP Elektromagnetische Detektionsanlage mit Falschalarmunterdrückung
EP0251210A1 (de) * 1986-06-25 1988-01-07 Media Security Incorporated And Associates Sicherheitssystem zum Datenschutz
USRE32627E (en) * 1981-09-10 1988-03-22 Sensormatic Electronics Corporation Electrical surveillance apparatus with moveable antenna elements
US4812822A (en) * 1987-08-31 1989-03-14 Monarch Marking Systems, Inc. Electronic article surveillance system utilizing synchronous integration
EP0494764A1 (de) * 1991-01-09 1992-07-15 Texas Instruments Incorporated Abfragestation zur Identifizierung von Gegenständen die, auf einer Förderanlage transportiert werden
EP0496611A1 (de) * 1991-01-23 1992-07-29 Texas Instruments Holland B.V. Antennensystem für eine Abfragestation zur Identifizierung von Gegenständen
EP0496610A2 (de) * 1991-01-23 1992-07-29 Texas Instruments Holland B.V. Abfragestation zur Identifizierung mit separaten Sende- und Empfangsantennen
US5349332A (en) * 1992-10-13 1994-09-20 Sensormatic Electronics Corportion EAS system with requency hopping
US5589820A (en) * 1993-10-05 1996-12-31 Pac/Scan, Inc. Retail theft prevention and information device
US5661470A (en) * 1994-03-04 1997-08-26 Karr; Gerald S. Object recognition system
US5790031A (en) * 1997-01-13 1998-08-04 Trw Inc. Apparatus and method for sensing a rearward facing child seat with error detection
US5825291A (en) * 1996-04-10 1998-10-20 Sentry Technology Corporation Electronic article surveillance system
US5990791A (en) * 1997-10-22 1999-11-23 William B. Spargur Anti-theft detection system
US20040257294A1 (en) * 2001-07-30 2004-12-23 Tony Bernard Loop-type antenna
US10726711B2 (en) 2017-05-01 2020-07-28 Johnson Controls Technology Company Building security system with user presentation for false alarm reduction

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DK145169C (da) * 1978-08-09 1983-02-21 Security Prod Int Anlaeg til registrering af en passage af en genstand gennem etforudbestemt omraade
GB9305085D0 (en) * 1993-03-12 1993-04-28 Esselte Meto Int Gmbh Electronic article surveillance system with enhanced geometric arrangement
DE19514601A1 (de) * 1995-04-20 1996-10-24 Esselte Meto Int Gmbh Anlage zur elektronischen Artikelüberwachung, insbesondere zur Detektion von Schwingkreisen mit stark unterschiedlichen Resonanzfrequenzen

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2794974A (en) * 1955-01-24 1957-06-04 Kidde & Co Walter Compensation for turbulence and other efects in intruder detection systems
US3218556A (en) * 1963-03-29 1965-11-16 Sierra Research Corp Spectrum centered receiver
US3465336A (en) * 1968-05-09 1969-09-02 Us Army Doppler radar with clutter controlled filter channel
US3577136A (en) * 1967-08-04 1971-05-04 Security Systems Inc Short-range signaling system
US3696379A (en) * 1970-12-02 1972-10-03 Knogo Corp Apparatus for article theft detection
US3711848A (en) * 1971-02-10 1973-01-16 I D Eng Inc Method of and apparatus for the detection of stolen articles
US3781860A (en) * 1972-02-14 1973-12-25 Williamson W Method and apparatus for inhibiting article theft
US3801977A (en) * 1971-12-07 1974-04-02 Gulf & Western Mfg Co Ultrasonic alarm circuit

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2794974A (en) * 1955-01-24 1957-06-04 Kidde & Co Walter Compensation for turbulence and other efects in intruder detection systems
US3218556A (en) * 1963-03-29 1965-11-16 Sierra Research Corp Spectrum centered receiver
US3577136A (en) * 1967-08-04 1971-05-04 Security Systems Inc Short-range signaling system
US3465336A (en) * 1968-05-09 1969-09-02 Us Army Doppler radar with clutter controlled filter channel
US3696379A (en) * 1970-12-02 1972-10-03 Knogo Corp Apparatus for article theft detection
US3711848A (en) * 1971-02-10 1973-01-16 I D Eng Inc Method of and apparatus for the detection of stolen articles
US3801977A (en) * 1971-12-07 1974-04-02 Gulf & Western Mfg Co Ultrasonic alarm circuit
US3781860A (en) * 1972-02-14 1973-12-25 Williamson W Method and apparatus for inhibiting article theft

Cited By (44)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4063230A (en) * 1975-06-12 1977-12-13 The Magnavox Company Balanced field theft detection system
US4016553A (en) * 1975-06-27 1977-04-05 Knogo Corporation Article detection system with near field electromagnetic wave control
US4045778A (en) * 1976-02-23 1977-08-30 Wagner Electric Corporation Dual channel wide-band frequency modulated keyable control circuit and keying circuit therefor
US4095214A (en) * 1976-06-17 1978-06-13 Knogo Corporation Electronic monitoring system and responder device
DE2725169A1 (de) * 1977-03-14 1978-09-21 Lichtblau G J Unterdrueckungsschaltung fuer schwebungsfrequenzstoerungen
US4117466A (en) * 1977-03-14 1978-09-26 Lichtblau G J Beat frequency interference rejection circuit
US4308530A (en) * 1977-07-19 1981-12-29 N.V. Nederlandsche Apparatenfabriek Nedap Detection system forming wide gates with superior spatial selectivity
FR2398357A1 (fr) * 1977-07-19 1979-02-16 Nedap Nv Dispositif de detection electromagnetique
US4135184A (en) * 1977-08-31 1979-01-16 Knogo Corporation Electronic theft detection system for monitoring wide passageways
DE2837637A1 (de) * 1977-08-31 1979-03-08 Knogo Corp Elektronisches diebstahl-sicherungssystem zur ueberwachung breiter durchgaenge
US4260983A (en) * 1978-01-11 1981-04-07 Tag Radionics Limited Presence sensing detector and system for detecting a receiver/transmitter device affixed to an article
EP0020062A1 (de) * 1979-05-18 1980-12-10 Parmeko Limited Verfahren und Überwachungssystem zur Feststellung der Anwesenheit eines Empfängers-Rücksenders für elektromagnetische Signale
US4532511A (en) * 1979-10-12 1985-07-30 Lemelson Jerome H Automatic vehicle identification system and method
US4281321A (en) * 1980-06-09 1981-07-28 Sensormatic Electronics Corporation Surveillance system employing a floor mat radiator
FR2484095A1 (fr) * 1980-06-09 1981-12-11 Sensormatic Electronics Corp Dispositif de surveillance employant un element rayonnant sous forme de tapis
FR2489001A1 (fr) * 1980-08-21 1982-02-26 Knogo Corp Procede et dispositif de detection electronique de vol d'articles
US4321586A (en) * 1980-08-21 1982-03-23 Knogo Corporation Article theft detection
DE3128980A1 (de) * 1980-08-21 1982-04-08 Knogo Corp., 11801 Hicksville, N.Y. Verfahren und vorrichtung zum schutz von gegenstaenden gegen diebstahl
US4481428A (en) * 1981-05-19 1984-11-06 Security Tag Systems, Inc. Batteryless, portable, frequency divider useful as a transponder of electromagnetic radiation
USRE32627E (en) * 1981-09-10 1988-03-22 Sensormatic Electronics Corporation Electrical surveillance apparatus with moveable antenna elements
EP0100128A1 (de) * 1982-07-21 1984-02-08 N.V. Nederlandsche Apparatenfabriek NEDAP Absorbierungsdetektoranlage
US4686517A (en) * 1982-07-21 1987-08-11 N.V. Nederlandsche Apparatenfabriek Nedap Field disturbance detection system
US4623877A (en) 1983-06-30 1986-11-18 Knogo Corporation Method and apparatus for detection of targets in an interrogation zone
EP0242901A1 (de) * 1986-03-24 1987-10-28 N.V. Nederlandsche Apparatenfabriek NEDAP Elektromagnetische Detektionsanlage mit Falschalarmunterdrückung
EP0251210A1 (de) * 1986-06-25 1988-01-07 Media Security Incorporated And Associates Sicherheitssystem zum Datenschutz
US4812822A (en) * 1987-08-31 1989-03-14 Monarch Marking Systems, Inc. Electronic article surveillance system utilizing synchronous integration
EP0494764A1 (de) * 1991-01-09 1992-07-15 Texas Instruments Incorporated Abfragestation zur Identifizierung von Gegenständen die, auf einer Förderanlage transportiert werden
EP0496611A1 (de) * 1991-01-23 1992-07-29 Texas Instruments Holland B.V. Antennensystem für eine Abfragestation zur Identifizierung von Gegenständen
EP0496610A2 (de) * 1991-01-23 1992-07-29 Texas Instruments Holland B.V. Abfragestation zur Identifizierung mit separaten Sende- und Empfangsantennen
EP0496610A3 (en) * 1991-01-23 1992-10-07 Texas Instruments Holland B.V. Interrogating station for identification purposes, with separate transmitting and receiving antennae
US5247304A (en) * 1991-01-23 1993-09-21 Texas Instruments Incorporated Interrogating station for identification purposes, with separate transmitting and receiving antennae
US5305002A (en) * 1991-01-23 1994-04-19 Texas Instruments Incorporated Hinged read-out antenna system
US5349332A (en) * 1992-10-13 1994-09-20 Sensormatic Electronics Corportion EAS system with requency hopping
US5589820A (en) * 1993-10-05 1996-12-31 Pac/Scan, Inc. Retail theft prevention and information device
US5661470A (en) * 1994-03-04 1997-08-26 Karr; Gerald S. Object recognition system
US5825291A (en) * 1996-04-10 1998-10-20 Sentry Technology Corporation Electronic article surveillance system
US5790031A (en) * 1997-01-13 1998-08-04 Trw Inc. Apparatus and method for sensing a rearward facing child seat with error detection
US5990791A (en) * 1997-10-22 1999-11-23 William B. Spargur Anti-theft detection system
US20040257294A1 (en) * 2001-07-30 2004-12-23 Tony Bernard Loop-type antenna
US7123210B2 (en) * 2001-07-30 2006-10-17 Pygmalyon Loop-type antenna
US10726711B2 (en) 2017-05-01 2020-07-28 Johnson Controls Technology Company Building security system with user presentation for false alarm reduction
US10832564B2 (en) 2017-05-01 2020-11-10 Johnson Controls Technology Company Building security system with event data analysis for generating false alarm rules for false alarm reduction
US10832563B2 (en) 2017-05-01 2020-11-10 Johnson Controls Technology Company Building security system with false alarm reduction recommendations and automated self-healing for false alarm reduction
US12062278B2 (en) 2017-05-01 2024-08-13 Tyco Fire & Security Gmbh Building security system with false alarm reduction recommendations and automated self-healing for false alarm reduction

Also Published As

Publication number Publication date
BE813708A (fr) 1974-10-14
FR2228258B1 (de) 1981-05-22
AU6740774A (en) 1975-10-02
JPS5010600A (de) 1975-02-03
DE2417928B2 (de) 1977-10-27
FR2228258A1 (de) 1974-11-29
AU474729B2 (en) 1976-07-29
IT1018645B (it) 1977-10-20
JPS5752637B2 (de) 1982-11-09
NL7404466A (de) 1974-10-15
CA1023034A (en) 1977-12-20
SE397145B (sv) 1977-10-17
DE2417928A1 (de) 1974-10-24
DE2417928C3 (de) 1978-06-15
NL161904B (nl) 1979-10-15
NL161904C (nl)
GB1440398A (en) 1976-06-23
ZA742089B (en) 1975-04-30

Similar Documents

Publication Publication Date Title
US3868669A (en) Reduction of false alarms in electronic theft detection systems
US4352098A (en) Surveillance systems
ES454749A1 (es) Sistema de seguridad electronico para establecimientos de venta de articulos.
EP0035660B1 (de) Detektion von Gegenständen in benachbarten Fussgängerpassagen
US3707711A (en) Electronic surveillance system
CA1240772A (en) Electronic surveillance system employing the doppler effect
US3624631A (en) Pilferage control system
US5245317A (en) Article theft detection apparatus
US3723966A (en) Interrogating tire pressure indicator
US3691558A (en) Moving object microwave detection system
US3818472A (en) R.f. system for detecting unauthorized travel of articles through a selected zone
US3889250A (en) Active frequency-responsive glass breakage detector
GB1446259A (en) Electronic theft detection system having uniform field strength
SE8205993D0 (sv) Theft detection method and apparatus in which the decay of a resonant circuit is detected
US4565996A (en) Range limited coherent frequency doppler surveillance system
US3932870A (en) On-line test circuit for intrusion alarm systems
KR830004992A (ko) 차량용 침입 경보장치
CA1234211A (en) Method and circuitry for the function control of ultrasonic alarm systems
US4117466A (en) Beat frequency interference rejection circuit
US3673590A (en) Device to detect motion
US6307474B1 (en) Magnetomechanical electronic article surveillance system and method using sideband detection
KR910005054A (ko) 무선 주파수 신호 검출 방법 및 장치
GB2050765A (en) Improvements In or Relating To Surveillance Systems
RU2138855C1 (ru) Элемент сигнализации
GB1582018A (en) Surveillance monitoring systems