EP0556910A1 - Fernidentifikationssystem mit passiver Identifikationsvorrichtung - Google Patents

Fernidentifikationssystem mit passiver Identifikationsvorrichtung Download PDF

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Publication number
EP0556910A1
EP0556910A1 EP93200396A EP93200396A EP0556910A1 EP 0556910 A1 EP0556910 A1 EP 0556910A1 EP 93200396 A EP93200396 A EP 93200396A EP 93200396 A EP93200396 A EP 93200396A EP 0556910 A1 EP0556910 A1 EP 0556910A1
Authority
EP
European Patent Office
Prior art keywords
passive identification
transmitter
receiver
identification device
crystal
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.)
Ceased
Application number
EP93200396A
Other languages
English (en)
French (fr)
Inventor
Hans Juergen Butterweck
Adrianus Cornelius Petrus Van Meer
Johannes Henricus Franciscus Ritzerfeld
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.)
WATERS EN GIJSBERS BEHEER BV
Original Assignee
WATERS EN GIJSBERS BEHEER BV
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 WATERS EN GIJSBERS BEHEER BV filed Critical WATERS EN GIJSBERS BEHEER BV
Publication of EP0556910A1 publication Critical patent/EP0556910A1/de
Ceased legal-status Critical Current

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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
    • G08B13/2405—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
    • G08B13/2417—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 having a radio frequency identification chip
    • 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
    • G08B13/2428—Tag details
    • G08B13/2431—Tag circuit details
    • 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
    • G08B13/2451—Specific applications combined with EAS
    • G08B13/2462—Asset location systems combined with EAS

Definitions

  • the invention relates to a passive identification device, comprising a resonance circuit, and to a system for remote identification of objects, comprising a transmitter, a receiver and a set of passive identification devices associated with the objects, which operate as a transponder for a receiver in response to operation of the transmitter.
  • the resonance circuit of the known passive identification device consists of a capacitor, which is connected to a small-sized coil, which provides magnetic coupling to an external field. Resonance is detected by means of a transmitter provided with a frequency-modulated generator sweeping around the resonance frequency. The receiver is then constructed such that it can discriminate between the resonance curve from the passive identification device and flatter responses from other objects in the region of detection.
  • the detection range amounts to maximally a few meters thereby.
  • the typical linear dimension of the passive identification device is 5 cm, whereby in practice, in order to avoid wave effects in the system, the quality factor of the passive identification device will not exceed 200 in a field having a frequency of considerably less than 200 MHz.
  • the known system Due to this low quality factor, in conjunction with the impossibility to produce these known passive identification devices with sufficient reproducibility and constancy of their resonance frequencies and the sensitivity of the system to objects not to be secured against theft, which generate a large signal at the receiver, the known system is inherently unsuitable for an identification system in a wider sense, which must also be able to identify objects of detection, which is why the known system leaves room for improvement as a detection system.
  • the object of the invention is to provide a reliable, low-cost, passive remote identification system.
  • the invention proposes a passive identification device of the kind mentioned in the preamble, which is characterized in that it is provided with a crystal coupled to the resonance circuit, as well as a system of the kind mentioned in the preamble, which is characterized in that the set of passive identification devices is composed of the proposed passive identification devices.
  • a passive identification device may comprise one crystal or several crystals having different frequencies, which are connected in parallel.
  • the set of passive identification devices may consist of passive identification devices containing one crystal, with the same frequency for each passive identification device, or of passive identification devices containing one crystal, which are selected from a set of a number of crystals having mutually different frequencies.
  • the set of passive identification devices may also consist of passive identification devices, each containing a first number of crystals having mutually different frequencies, which are selected from a set of a second number of crystals, which is larger than the first number of crystals, having mutually different frequencies, or of passive identification devices containing different numbers of crystals, which are selected from a set of a number of crystals having mutually different frequencies.
  • the crystals are preferably quartz crystals, since they are small, inexpensive and reliable.
  • the resonance circuit is preferably a parallel circuit of a coil and a capacitor, since they may be small-sized in the present invention.
  • the coupling between crystal and resonance circuit is preferably an inductive coupling, since this prevents the series resonance of the crystal from being overloaded, whilst a good reproducibility can be obtained.
  • the coupling may be a branched or an isolated coupling.
  • the coil may consist of an open wire loop, whereby the capacitor is connected across the ends of the wire loop.
  • the crystal(s) is (are) connected to two branching points of the wire loop, whereas in the latter case the crystal(s) is (are) connected across the ends of a respective open wire loop, whilst all wire loops are located in proximity to each other.
  • the wire loop may be a conductor track provided on a carrier.
  • the proposed identification device may be a label, a card or the like.
  • the proposed system in which the set of passive identification devices is composed of passive identification devices containing one crystal, with the same frequency for each passive identification device, is preferably arranged such that the transmitter is switched for intermittently transmitting a transmission signal at the frequency of the crystal, and that the receiver is switched for intermittently receiving a response signal from a passive identification device receiving the transmission signal from the transmitter, demodulating the response signal, performing a matched filter operation and detecting the object based on the resulting output signal.
  • the system is preferably arranged in such a manner that the transmitter is switched for intermittently transmitting a transmission signal consisting of a given number of summed signals at the respective frequencies of the given number of crystals, and that the receiver is switched for intermittently receiving a response signal from a passive identification device receiving the transmission signal from the transmitter, demodulating said response signal in a given number of channels, performing a matched filter operation in each channel and identifying the object based on output signals in said given number of channels.
  • the transmitter and the receiver may be switched at a frequency in the order of 1 kHz.
  • a time-delay is provided between switching off of the transmitter and switching on of the receiver, so that echoes from interfering objects in the scanned spaces have faded away.
  • This time-delay may be in the order of 10 ⁇ s.
  • the transmission frequencies used should be below 30 MHz in case of an region of detection of 1 - 2 metres in each horizontal direction.
  • the transmission frequencies are substantially 27 MHz, for example frequencies of 26.91 - 27.10 MHz in steps of 10 kHz.
  • the proposed passive identification device is used for identifying living objects, such as people and animals, or lifeless objects, such as goods and vehicles, with the proposed system being used for monitoring, security or logistic purposes.
  • access control, electronic security, vehicle identification, monitoring of livestock and stock control may be considered, as well as theft prevention in shops or department stores.
  • identification is also meant to include detection.
  • an open wire loop 1 constitutes a coil, across whose ends 2 and 3 a capacitor 4 is connected, whilst a crystal 5 is connected to of two branching points 6 and 7 the wire loop 1.
  • the wire loop 1 may be formed on a carrier (not shown) by vapor deposition, or the coil 1 might consist of a plurality of windings in applications where this would not constitute a drawback.
  • one crystal 5 is shown, several crystals 5, each having a different frequency, may be connected in parallel.
  • Figure 2 shows a circuit diagram associated with Figure 1, with three crystals 5 being used.
  • the crystal 5 is preferably a quartz crystal, since it has a well-defined, stable and reproducible resonance frequency, as well as a high quality factor of about 105.
  • the coupling of the crystal 5 to the resonance circuit 1, 4 may take place in an inductive, isolated or capacitive, but not in a direct manner, since this will lead to overloading of the series resonance of the crystal 5, whereby in practice the drawback of capacitive coupling is that the coupling capacitor (not shown) must have values of a few picofarad or less, which are difficult to reproduce.
  • Figure 1 illustrates inductive coupling of the resonance circuit 1, 4 in the form of branching the coil 1, one winding in this case.
  • an additional, loose wire loop (not shown) is used with the crystal 5.
  • the passive identification device may be given a possibly interchangeable identity afterwards, by attaching a crystal 5 plus wire loop to the carrier (not shown).
  • the passive identification device may be very small-sized. With a coil 1 diameter of 4 cm, the self-induction of the coil 1 is 100 nH, from which it follows that for resonance at the said frequency the capacity of the capacitor 4 is 350 pF.
  • a ceramic capacitor having this value is small and inexpensive and has very low losses, although it is also possible to use a paper capacitor or a capacitor formed by vapor deposition.
  • the resonance circuit 1, 4 has a high quality factor as a result of low losses, which are then determined by the coil 1, which has only one winding.
  • the degree of coupling of one or more crystals 5 to the resonance circuit 1, 4 influences the magnitude of the response signal from the passive identification device, which will be discussed hereafter, as well as the possibility of a correct identification of the passive identification device.
  • the crystal 5 should exhibit a load of about 10 times its own series resistance. This results in a 90% dip in the resonance curve of the resonance circuit 1, 4, as will be seen hereafter in the description of Figure 4, at the frequency of the crystal or crystals 5, and thus in a practically maximal detection possibility of the crystal or crystals 5.
  • the crystal or each crystal 5 retains 10% of its unloaded quality factor, so that the dips resulting from different crystals 5 are sufficiently pronounced to enable reliable identification. All this implies that the time constant ⁇ of the response signal from the passive identification device is given by 0.1 x 2 Qk/w, where Qk is the quality factor, which amounts to about 120 ⁇ s at the given frequency.
  • Figure 2 shows a circuit diagram of a passive identification device with three crystals 5 connected in parallel, which are connected to a tap 8 of the coil 1 of a common resonance circuit 1, 4.
  • Figure 3 shows an equivalent circuit depicting the crystals 5 as series resonance circuits 9, which have an unloaded quality factor Qx at different resonance frequencies w1, w2 and w3.
  • the equivalent circuit of Figure 3 also illustrates the loss-representing resistance R0 of the resonance circuit 1, 4, together with the central frequency w0 and the quality factor Q0 thereof.
  • the shunt capacity that is responsible for the parallel resonance of a quartz crystal 5 is small, and may be considered incorporated in the capacity C0.
  • the parameter ⁇ may be used for controlling the ratio R0/R1, which will be called the crystal load factor ⁇ .
  • R0/R1 which will be called the crystal load factor ⁇ .
  • Figure 4 shows
  • the resonance frequencies of the crystals 5 are so far apart that 20 sharp series resonances fit between these -3 dB points, so that twenty crystals 5 can be used.
  • one of the crystal frequencies coincides with ⁇ - 0, whilst the other two are as proximate as possible thereto.
  • the crystal load factor ⁇ determines the depth and the width of the dip 11 in the main resonance curve 10. These characteristics are significant because the depth, the amplitude and the width determine the time constant of the natural response to be detected.
  • ⁇ 10 applies.
  • each passive identification device comprises three crystals 5 having mutually different frequencies, which are selected from a set of twenty crystals 5 having mutually divergent frequencies, so that there are 1140 possible identities, which number is given by the binomial coefficient 20 above 3; more generally m above k, whereby m > k > 1 applies.
  • the set of passive identification devices is composed of passive identification devices containing one crystal 5, with the same frequency for each passive identification device.
  • Simple identification that is with a relatively low number of identities, is possible with a set of passive identification devices consisting of passive identification devices containing one crystal, which are selected from a set of a number of crystals 5 having mutually different frequencies.
  • the system comprises a set of proposed passive identification devices associated with the objects, which operate as a transponder for the receiver portion of the transmitter-receiver in response to operation of the transmitter portion of the transmitter-receiver.
  • a passive identification device is indicated at 20, the transmitter portion or the transmitter being indicated at 21 and the receiver portion or the receiver at 22, whilst reference numeral 36 indicates the antenna, a common antenna in this case.
  • Figure 6 illustrates from top to bottom various signal waveforms 31 - 35 occurring at respective points in the diagram of Figure 5.
  • Reference numeral 23 in Figure 5 indicates a number of modulators, for example 20, each containing a crystal-tuned oscillator (not shown) for the possible crystal frequencies (twenty in this case), three of said frequencies, still with respect to the above-described embodiment, always being present in a passive identification device.
  • signal waveforms 31 - 35 of Figure 6 only relate to a single frequency. See signal waveform 31 in this connection, which is present at the output of a summing device 24 shown in Figure 5, which receives at its inputs the output signals from the modulators 23.
  • the amplifiers 25 and 27 in Figure 5 provide buffering, amplification and reception for the transmitter-receiver antenna 36.
  • the timing is taken care of by the switching device 26, which may comprise a block wave generator and which generates two switching signals, one for the transmitter amplifier 25 and one for the receiver amplifier 27.
  • the signal waveform 32 in Figure 6 is transmitted, whilst the signal waveform 33 is received back, whereby the damped oscillation 41 during the off-phase of the transmitter 21 indicates the presence of the passive identification device 20.
  • the passive identification device 20 responds to exactly three of these frequencies with the damped oscillation 41, thus revealing its identity to the receiver 22.
  • the damped oscillation 41 from the passive identification device will be much weaker than is suggested for the sake of clarity by the signal waveform 33. Suppression of the much stronger transmission signal 2 eventually leads to the signal waveform 34 at the output of the receiver amplifier 27.
  • the timing or the switching of the transmitter 21 and the receiver 22 is determined by the following considerations.
  • the time constant ⁇ 120 ⁇ s calculated before indicates the speed at which the oscillation 41 of the passive identification device is damped. If as a rule reception takes place during a time interval of 3 ⁇ to 4 ⁇ , followed by transmission for a similar period, this leads to a switching frequency of 1 kHz. In this connection it is important that a time-delay of 10 ⁇ s is provided between switching off of the transmitter 24 and switching on of the receiver 27, in order to be sure that all echoes from interfering objects in a scanned space have faded away. This delay provides a significant reliability gain in comparison with systems that use frequency sweeping.
  • the "central" transmission frequency is selected so that there are no radiation effects, which means that all objects to be detected are present in the near field of the transmitter-receiver antenna.
  • the advantages being a very compact scanning area, which does not produce any outward interference, as a result of which Official requirements (PTT in the Netherlands) can be satisfied without any difficulty, whilst moreover little interference is caused by outside influences, and that the entire scanning area is simultaneously scanned in all directions, for example 1 - 2 metres in every horizontal direction, which provides an upper limit for the transmission frequency; with a wavelength of 10 m or more the frequency should namely be 30 MHz or less.
  • the transmission frequency is also selected in dependence on the passive identification device.
  • the quality factor of the resonance circuit 1, 4 which makes the passive identification device present in the field detectable, should be as large as possible.
  • the fact is that the response signal from the passive identification device is directly proportional to the quality factor of the resonance circuit.
  • the quality factor of the crystals 5 should likewise be as large as possible, in order to achieve the largest possible resolution. Both said quality factors increase along with the transmission frequency.
  • the switching frequency for the transmitter 21 and the receiver 22 for on/off operation may be raised with an increasing transmission frequency, which results in greater system reliability.
  • the product of the self-induction and the capacity of the resonance circuit 1, 4 is smaller, so that a smaller-sized passive identification device can be used because of the possibility to use a smaller coil 1, whilst retaining suitable values for the associated capacitor 4.
  • a number of demodulators 28, twenty in this case mixes the amplified response signal 34 in twenty channels pack to the baseband, which leads to the signal waveform 35 of Figure 6.
  • said number of demodulators comprises respective mixers (not shown), which multiply the response signal 34 by the respective frequencies generated by the number of modulators 23.
  • the modulators 23 and the demodulators 28 may each comprise a respective common crystal oscillator (not shown) for generating a respective transmission frequency and for use in demodulation by a respective demodulator 28. All the same there is no synchronous or coherent detection, since the response signal 34 from the passive identification device necessarily has a free-running phase.
  • the demodulators 28 are quadrature modulators. As an alternative for these asynchronous or incoherent demodulation envelope detection may be used. In that case respective frequency-selective devices (not shown) must be provided in front of the demodulators.
  • the time duration of exposure of the passive identification device in the scanned area may vary. If this is for example set at 0.1 s, more than 100 response signals 34 can be correlated at a switching frequency of 1 kHz. In that case a signal-to-noise ratio of 0 dB proves to be sufficient for reliable identification, with an error probability of 10-5. Indeed a great many variants to this principle are possible.
  • the optimum receiver 22 for example does not just sum 100 integration partial results, but the square of these interim results. In that case we have an optimum n-fold time diversity. Selection of a variable value k will of course increase the complexity of the final identification device 30. In that case optimum decoding for the most probable identity must be carried out. Possibly error correction may be carried out by means of redundance in the identity code.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Automation & Control Theory (AREA)
  • Computer Security & Cryptography (AREA)
  • Electromagnetism (AREA)
  • General Physics & Mathematics (AREA)
  • Burglar Alarm Systems (AREA)
EP93200396A 1992-02-19 1993-02-15 Fernidentifikationssystem mit passiver Identifikationsvorrichtung Ceased EP0556910A1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
NL9200304 1992-02-19
NL9200304A NL9200304A (nl) 1992-02-19 1992-02-19 Afstandsidentificatiestelsel met passieve identificatie-inrichtingen.

Publications (1)

Publication Number Publication Date
EP0556910A1 true EP0556910A1 (de) 1993-08-25

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EP93200396A Ceased EP0556910A1 (de) 1992-02-19 1993-02-15 Fernidentifikationssystem mit passiver Identifikationsvorrichtung

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EP (1) EP0556910A1 (de)
NL (1) NL9200304A (de)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0674354A2 (de) * 1994-03-24 1995-09-27 Hochiki Corporation Drahtloses Zugangskontrollsystem mit Annäherungselement unt Antenneneinrichtung hierfür
FR2754910A1 (fr) * 1996-10-22 1998-04-24 Solaic Sa Etiquette de securite a circuit resonant
EP0984384A2 (de) * 1998-08-31 2000-03-08 Magnex Corporation Kollektivobjektverwaltungssystem mit Radiofrequenzobjektidentifizierung
EP1058214A1 (de) * 1999-06-01 2000-12-06 Valeo Securité Habitacle Verfahren zur bidirektionalen Datenübertragung und System zur Ausführung derselben
EP1280093A2 (de) * 2001-07-24 2003-01-29 Hewlett-Packard Company System und Verfahren zur verbesserten Objektidentifikation
EP1374196A1 (de) * 2001-03-26 2004-01-02 Sensormatic Electronics Corporation Digitale detektionsfilter für die elektronische artikelsicherung
US6698119B2 (en) 2001-01-11 2004-03-02 Farnam Companies, Inc. Decorated ear tags for domestic animals and method of making same
US6989918B2 (en) 2001-07-24 2006-01-24 Hewlett-Packard Development Company, L.P. Transparency adapter with light table
WO2011073657A3 (en) * 2009-12-15 2012-03-15 Isis Innovation Ltd Asset detection apparatus and method
CN112041902A (zh) * 2018-03-05 2020-12-04 先讯美资电子有限责任公司 对基于am铁氧体的标记器的支持rfid式去激活***和方法

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0131440A1 (de) * 1983-07-05 1985-01-16 Minnesota Mining And Manufacturing Company Elektronisches RF-Überwachungssystem mit variabler Frequenz
WO1988000785A1 (en) * 1986-07-18 1988-01-28 B.I. Incorporated Transponder device

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0131440A1 (de) * 1983-07-05 1985-01-16 Minnesota Mining And Manufacturing Company Elektronisches RF-Überwachungssystem mit variabler Frequenz
WO1988000785A1 (en) * 1986-07-18 1988-01-28 B.I. Incorporated Transponder device

Cited By (22)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0674354A3 (de) * 1994-03-24 1996-07-17 Hochiki Co Drahtloses Zugangskontrollsystem mit Annäherungselement unt Antenneneinrichtung hierfür.
US5808587A (en) * 1994-03-24 1998-09-15 Hochiki Corporation Wireless access control system using a proximity member and antenna equipment therefor
EP0674354A2 (de) * 1994-03-24 1995-09-27 Hochiki Corporation Drahtloses Zugangskontrollsystem mit Annäherungselement unt Antenneneinrichtung hierfür
FR2754910A1 (fr) * 1996-10-22 1998-04-24 Solaic Sa Etiquette de securite a circuit resonant
WO1998018027A1 (fr) * 1996-10-22 1998-04-30 Schlumberger Systemes Etiquette de securite a circuit resonant
EP0984384A2 (de) * 1998-08-31 2000-03-08 Magnex Corporation Kollektivobjektverwaltungssystem mit Radiofrequenzobjektidentifizierung
EP0984384A3 (de) * 1998-08-31 2002-05-29 Magnex Corporation Kollektivobjektverwaltungssystem mit Radiofrequenzobjektidentifizierung
US6657536B1 (en) 1999-06-01 2003-12-02 Valeo Securite Habitacle Process for the bidirectional transmission of data and system for the implementation thereof
EP1058214A1 (de) * 1999-06-01 2000-12-06 Valeo Securité Habitacle Verfahren zur bidirektionalen Datenübertragung und System zur Ausführung derselben
FR2794603A1 (fr) * 1999-06-01 2000-12-08 Valeo Securite Habitacle Procede de transmission bidirectionnelle de donnees, et systeme pour sa mise en oeuvre
US6698119B2 (en) 2001-01-11 2004-03-02 Farnam Companies, Inc. Decorated ear tags for domestic animals and method of making same
EP1374196A4 (de) * 2001-03-26 2006-02-01 Sensormatic Electronics Corp Digitale detektionsfilter für die elektronische artikelsicherung
EP1374196A1 (de) * 2001-03-26 2004-01-02 Sensormatic Electronics Corporation Digitale detektionsfilter für die elektronische artikelsicherung
EP1280093A3 (de) * 2001-07-24 2003-09-03 Hewlett-Packard Company System und Verfahren zur verbesserten Objektidentifikation
US6989918B2 (en) 2001-07-24 2006-01-24 Hewlett-Packard Development Company, L.P. Transparency adapter with light table
EP1280093A2 (de) * 2001-07-24 2003-01-29 Hewlett-Packard Company System und Verfahren zur verbesserten Objektidentifikation
US7274285B2 (en) 2001-07-24 2007-09-25 Hewlett-Packard Development Company, L.P. System and method for improved object identification
WO2011073657A3 (en) * 2009-12-15 2012-03-15 Isis Innovation Ltd Asset detection apparatus and method
GB2488959A (en) * 2009-12-15 2012-09-12 Isis Innovation Asset detection apparatus and method
GB2488959B (en) * 2009-12-15 2012-11-07 Isis Innovation Asset detection apparatus and method
US8760166B2 (en) 2009-12-15 2014-06-24 Isis Innovation Limited Resonant assembly, system and method for identification of a buried asset
CN112041902A (zh) * 2018-03-05 2020-12-04 先讯美资电子有限责任公司 对基于am铁氧体的标记器的支持rfid式去激活***和方法

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