US3755803A - Electronic surveillance system - Google Patents

Electronic surveillance system Download PDF

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Publication number
US3755803A
US3755803A US00024319A US3755803DA US3755803A US 3755803 A US3755803 A US 3755803A US 00024319 A US00024319 A US 00024319A US 3755803D A US3755803D A US 3755803DA US 3755803 A US3755803 A US 3755803A
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energy
label
signals
resonator
receiver
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US00024319A
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P Cole
R Vaughn
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Unisearch Ltd
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Unisearch Ltd
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    • 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
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
    • G06K19/00—Record carriers for use with machines and with at least a part designed to carry digital markings
    • G06K19/06—Record carriers for use with machines and with at least a part designed to carry digital markings characterised by the kind of the digital marking, e.g. shape, nature, code
    • G06K19/067—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components
    • G06K19/0672—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components with resonating marks
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
    • G06K7/00—Methods or arrangements for sensing record carriers, e.g. for reading patterns
    • G06K7/0008—General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
    • G06K7/00—Methods or arrangements for sensing record carriers, e.g. for reading patterns
    • G06K7/02—Methods or arrangements for sensing record carriers, e.g. for reading patterns by pneumatic or hydraulic means, e.g. sensing punched holes with compressed air; by sonic means ; by ultrasonic means
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
    • G06K7/00—Methods or arrangements for sensing record carriers, e.g. for reading patterns
    • G06K7/08—Methods or arrangements for sensing record carriers, e.g. for reading patterns by means detecting the change of an electrostatic or magnetic field, e.g. by detecting change of capacitance between electrodes
    • G06K7/082—Methods or arrangements for sensing record carriers, e.g. for reading patterns by means detecting the change of an electrostatic or magnetic field, e.g. by detecting change of capacitance between electrodes using inductive or magnetic sensors
    • G06K7/083—Methods or arrangements for sensing record carriers, e.g. for reading patterns by means detecting the change of an electrostatic or magnetic field, e.g. by detecting change of capacitance between electrodes using inductive or magnetic sensors inductive
    • G06K7/086—Methods or arrangements for sensing record carriers, e.g. for reading patterns by means detecting the change of an electrostatic or magnetic field, e.g. by detecting change of capacitance between electrodes using inductive or magnetic sensors inductive sensing passive circuit, e.g. resonant circuit transponders
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
    • G06K7/00—Methods or arrangements for sensing record carriers, e.g. for reading patterns
    • G06K7/10—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation
    • G06K7/10009—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation sensing by radiation using wavelengths larger than 0.1 mm, e.g. radio-waves or microwaves
    • 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
    • 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
    • G08B13/2437—Tag layered structure, processes for making layered 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

Definitions

  • the label is constructed to produce the 3,63l,442 l2/l97l FCUBI'OH 343/6.8 reply signal in a form of energy different from that of 31500373 3/l970 Mmasy 340/280 x the original transmitted signal. It is preferred that the gzgagg' first form of energy is accoustic energy and the second 3:52l:280 7/1970 Janco et all. .3. 343/6.8 energy is electmmagnefic energy 3,399,405 8/1968 Daniel, Jr. 343/6.8 X 14 Claims, 6 Drawing Figures TRANS/M7752 ANTi/V/VA 05mm g LABEL MAa/wmm.
  • the facilities offered by the present invention provide for the open or secret interrogation by radio and- /or acoustic waves of information from prepared passive labels by a remote sensing apparatus.
  • the intended application of the invention is in the prevention of theft of merchandise from shops or warehouses, of books in libraries or of appropriate items in factories or other places, by tagging such items with a label and locating a receiver covering each exit so that the unauthorised passage of such tagged items through each exit will be detected.
  • the basic principle of operation of any interrogating system for passive labels is as follows. Energy in some form is transmitted to the label by a transmitter and transmitting antenna unit. This energy is then processed in some way by the label, and the resulting energy retransmitted by the label as a reply" signal. This reply energy is then detected, suitably processed and information extracted therefrom by a sensitive receiver and receiving antenna unit. It is basic to all interrogation systems that the very small reply energy from the label be distinguished from the very much larger transmitter or interrogation energy. This distinction can be obtained by various methods; the present invention utilises a method which achieves the desired result by incorporating means in the label capable of changing the type of the energy, so that the reply energy is of a different type from the interrogate energy. For example in the system described below, the interrogate energy is in the form of acoustic energy while the reply energy is in the form of magnetic field energy.
  • the labels are passive, with indefinitely long storage life, can be read non destructively, are durable under various environmental and handling conditions, are small and have low manufacturing cost.
  • the labels can have any orientation relative to and considerable distance from the-sensing apparatus, can be in motion, and can be separated from the sensor by optically opaque barriers.
  • the signal is distinguishable from background clutter signals accidentally produced by the environment of the label being interrogated.
  • a distinction from clutter signals and the encoding of the information is made by choosing a combination of the type of interrogate energy and type of reply energy such that apart from the label, objects found in nature do not possess the necessary combination of characten istics to enable them to receive the type of interrogation energy, to convert this energy to the correct type of reply energy, and then re-radiate this reply energy in the correct way.
  • FIG. I is a block diagram showing the basic components of the system
  • FIG. 2 is an isometric view of a label card for use with the system
  • FIGS. 3 and 4 are views in plan and elevation of the label card showing further details
  • FIG. 5 shows one electrode configuration for the resonator incorporated in the label.
  • FIG. 6 is a block diagram of a pulsed system.
  • the system to be described is intended for detecting the presence only of a label at a distance of l metre, as might be required for example in a theft-detection system.
  • the general principleof the system is to provide in the label card a means of receiving energy in acoustic fonn, converting it to electromagnetic energy, and reradiating it as electromagnetic energy or more precisely in this case as magnetic energy. Since the transmitted energy is in acoustic form, and the reply from the label is in a different energy form, namely magnetic, it is thus possible to separate the small label reply from the large transmitted interrogate signal.
  • the basic components of the system are shown in the block diagram in FIG. 1.
  • the system consists of a.
  • a suitable electrical-to-acoustic energy transducer and acoustic antennae unit 2 (For example a barium titanate piezoelectric resonator coupled to the atmosphere by an acoustic horn) which is driven by the power oscillator l and radiates acoustic energy through the air illuminating the volume through-out which it is desired to detect the label,
  • a magnetic coil pair 4 connected to a sensitive receiver 5 which detects the reply magnetic field produced by the label when illuminated by the acoustic field.
  • FIG. 2 The construction of a suitable passive label is shown in the isometric drawing FIG. 2.
  • the label consists of an inner plastic card 6 approximately 2 by 1 inches in size which serves as a protection and supporting substrate for the inner sensitive elements.
  • Cardboard covers 7 and 8 sufficiently thin so as to be essentially transparent to I00 kc/s acoustic radiation, are glued to each side of the plastic card. Further details of the label are shown in FIGS. 3 and 4. In FIG. 3 the plastic card 6 and sensitive element 5 are shown with the cardboard covers 7 and 8 removed.
  • the acoustic energy is detected by its action in causing resonant vibration of a I00 kc/s flexural-mode resonator 9.
  • the resonator 9 shall be taken as being made of quartz, however any other material having suitable mechanical properties, low acoustic damping, and high piezoelectric coefficients could be used.
  • the flexural vibration mode is used to lower the acoustic impedance level of the resonator and hence to provide a better acoustic impedance match to the air.
  • Approximate dimensions of the resonator 9 are 1.5 cm long by 0.75 cm wide by 0.010 inch thick.
  • the resonator 9 is set into a cut-out in the plastic card 6, between but not in contact with the cardboard covers 7 and 8. In order to cause minimum damping by its support, it is held at the flexural-mode vibrational nodal-points by four dimples projecting from the sides of the cut-out in the plastic card.
  • Suitable electrodes are plated onto the resonator 9, one possible electrode configuration being shown in FIG. 5, such that the acoustic vibrational energy in the resonator is converted to electrical energy available between the electrodes 10 and 11 through the piezoelectric properties of the quartz.
  • This electrical energy or more precisely the piezoelectric displacement current between electrodes 10 and 11, produces a current through a 10 turn, one square inch area coil 12 connected between electrodes and 11.
  • Coil 12 is conveniently produced on the surface of the plastic card 6 by well-known printed circuitboard techniques. The magnetic field produced by this current flow through coil 12 is then detected by the Helmohltz coil pair 4 and receiver 5, thus enabling the presence of the label to be detected as required.
  • Magnetic propogation loss between the reactive power available at the resonator 9 output electrodes 10 and 11 to the real power magnetically induced in the receiving coil-pair 4 75db.
  • the overall transmission path loss is thus l29db.
  • the noise bandwidth of the receiver is 1000 c/s. Narrower bandwidths are not practical due to the acoustic Doppler shift associated with a person carrying the label through the field.
  • the consequent input noise level of the receiver allowing for a receiver noise figure of 3db is 17ldbW. With a transmitted power of.+ 20 dbW, the input signal level at the receiver is l09dbW.
  • the signal-to-noise ratio at the receiver is thus 62db and the system is not receiver noise limited.
  • the frequency of operation of the system can be decreased or increased. Decreasing the frequency improves the system signal to noise ratio, however the size of the label is also increased. Increasing the frequency reduces the system signal to noise ratio and decreases the size of the labels.
  • the attenuation of acoustic waves through the air also increases with frequency and this has the important advantage of increasing the discrimination of the system against spurious signals from labels outside the desired detection volume since these signals suffer attenuation due to the longer acoustic propogation path. For example at an operating frequency of 200 KHZ acoustic attenuation in air is 8 db/m. Consequently signals from extraneous labels will be attenuated by 8 db per metre of their distance from the detection volume.
  • the system can also be operated in reverse in the sense that magnetic field energy can be transmitted to the label by the coil-pair 4, converted to and re-radiated as acoustic energy by the label, and this acoustic energy received by the acoustic transducer-antenna 2.
  • This alternative system can have advantages in installations where the atmospheric magnetic field noise energy is higher than the atmospheric acoustic noise energy. Atmospheric acoustic noise energy is normally low at 100 KHZ and increasingly so at higher frequencies due to the acoustic attenuation of the air at these frequencies.
  • suitable values are a transmitter pulse length of 6 m/sec, a pulse repetition period of 300 m/sec, with the receiver synchronously gated on for a 3 m/sec period following 3 m/sec after the commencement of each transmitter pulse.
  • FIG. 6 One particular embodiment of such a pulse system is shown in FIG. 6. The principal components are:
  • a 37 db, l00kc/s gated power amphifier 14 which when gated on by pulse generator 15 delivers W average power, 5 kW peak power to antenna unit 21. Amplifier 14 is gated on for a 6 msec pulse period with a pulse repetition period of 300 in see by pulse generator 15.
  • a magnetic coil pair 24 connected to a sensitive receiver 18 which detects the reply magnetic field produced by the label when illuminated by the acoustic field.
  • the bandwidth of receiver 18 is l000c/s.
  • a gate 19 following receiver 18 which is gated open by pulse generator 17 for a 3 m sec period following 3 in see after the commencement of each transmitter pulse.
  • a final amplifier and detector unit 20 of bandwidth l000c/s which operates an appropriate alarm equipment if the detector output exceeds a certain threshold level during the on-gated period.
  • An as table multivibrator pulse generator 15 which provides a 6 in sec pulse having a 300 in sec pulse repetition rate to gated amplifier 14 plus a trigger pulse to delay generator 16 synchronised with the leading edge of the gating pulse to 14.
  • a monostable multivibrator pulse generator 16 which is triggered by the trigger pulse from 15 and hence provides a second trigger pulse to pulse generator l7 delayed 3 m see after the trigger pulse from l5.
  • a monostable pulse generator 17 which is triggered by the delayed trigger pulse from 16 and whence provides a 3 m sec duration on-gating pulse to receiver gate 19.
  • the particular embodiment herein described has used in the label a resonator of piezoelectric material which converted received acoustic energy to electrical energy by menas of the piezoelectric effect. It is also possible to use a resonator of magnetostrictive material which converts received acoustic energy to electrical energy by means of the magnetostructive effect. In the latter case the fluctuating magnetic moment induced in the magnetostrictive material would be detected directly by a receiver coil-pair 4 and no transmitting coil 12 would be necessary on the label.
  • An electronic surveillance system comprising transmitter means for transmitting signals having a first form of energy, a passive label for attachment to an article to be placed under surveillance, signal answering means mounted on said label for receiving the signals from said transmitting means and producing signals having a second form of energy and corresponding to the received signals, receiver means responsive to the signals transmitted by said signal answering means for receiving and processing the signals of the second form of energy, control means for defining a surveillance volume, said control means including modulator means coupled to said transmitter means and rendering said receiver means unresponsive to signals from said answering means when the phase of the signals from said answering means relative to the phase of signals from said transmitter means exceeds a given value.
  • said modulator means constrains said transmitter means to produce a series of regular pulses and gate said receiver means synchronously so as to switch on said receiver means at a predetermined time after the commencement of each transmitter pulse and for a predetermined period.
  • said answering means includes second receiver means on said label for receiving the signals of the first form of energy, transducer means on said label coupled to said receiver means for responding to the signals on said second receiver means for forming signals of the second form of energy, and second transmitter means on said label responsive to said transducer means for transmitting the signals of the second form of energy.
  • said answering means includes an electroacoustic resonator on said label.
  • said answering means includes an antenna connected to said resonator.
  • said label includes a plastic card having a cutout
  • said answering means including a piezoelectric resonator adapted to vibrate in a flexural mode, said resonator including electrodes attached to the surface of said piezoelectric resonator, and an antenna formed on the surface of the card connected to said electrodes.

Abstract

An electronic surveillance system in which a passive label attached to an article under surveillance is interrogated by means of a transmitted signal in a first form of energy, the label using the energy of that signal to return a signal to a receiver which gives an indication of the presence of the label if a reply signal has predetermined characteristics. In order to enable the receiver to distinguish the reply signal from the original transmitted signal the label is constructed to produce the reply signal in a form of energy different from that of the original transmitted signal. It is preferred that the first form of energy is accoustic energy and the second form of energy is electromagnetic energy.

Description

United tates 1 1 Cole et ai. Aug. 28, 1973 ELECTRONIC SURVEILLANCE SYSTEM 2',s99,s46""'8/19s9 Hollmann gig/2.:
. 2,774,060 l2 1956 Th [75] Invemm Adelalde; 3,493,955 2/ 1970 340/258 Richard Vaughn Mamubra N 3,577,136 5/1971 Wolf 340/280 uth Wales. both of Australia 3,389,391 6/1968 Keeler et a]. 343/6.8 [73] Assignee: Unisearch Limited, Kensington, New FOREIGN PATENTS OR APPLICATIONS wales l,085,7 04 10/1967 Great Britain 340/280 [22] Filed: Mar. 31, 1970 1 Primary Examiner-John W. Caldwell [2]] Appl' 2431? V 7 mm Assistant ExamineF-Scott F. Partridge Foreign Application Priority Data Attorney-McGlcw & Toren Apr. 2, 1969 Australia ..52968/69 ABSTRACT An electronic surveillance system in which a passive 'i 253; label attached to an article under surveillance is inter- [58] m i 340/258 280 282 rogated by means ofa transmitted signal in a first form 3 g z 5 I 310/8 8 of energy, the label using the energy of that signal to return a signal to a receiver which gives an indication of the presence of the label if a reply signal has predeter- [56] References Cited mined characteristics. In order to enable the receiver UNITED STATES PATENTS to distinguish the reply signal from the original trans- 3,432,852 3/1969 Arnold 343/ mitted signal the label is constructed to produce the 3,63l,442 l2/l97l FCUBI'OH 343/6.8 reply signal in a form of energy different from that of 31500373 3/l970 Mmasy 340/280 x the original transmitted signal. It is preferred that the gzgagg' first form of energy is accoustic energy and the second 3:52l:280 7/1970 Janco et all. .3. 343/6.8 energy is electmmagnefic energy 3,399,405 8/1968 Daniel, Jr. 343/6.8 X 14 Claims, 6 Drawing Figures TRANS/M7752 ANTi/V/VA 05mm g LABEL MAa/wmm.
ELECTRONIC SURVEILLANCE SYSTEM The facilities offered by the present invention provide for the open or secret interrogation by radio and- /or acoustic waves of information from prepared passive labels by a remote sensing apparatus.
The intended application of the invention is in the prevention of theft of merchandise from shops or warehouses, of books in libraries or of appropriate items in factories or other places, by tagging such items with a label and locating a receiver covering each exit so that the unauthorised passage of such tagged items through each exit will be detected.
The basic principle of operation of any interrogating system for passive labels is as follows. Energy in some form is transmitted to the label by a transmitter and transmitting antenna unit. This energy is then processed in some way by the label, and the resulting energy retransmitted by the label as a reply" signal. This reply energy is then detected, suitably processed and information extracted therefrom by a sensitive receiver and receiving antenna unit. It is basic to all interrogation systems that the very small reply energy from the label be distinguished from the very much larger transmitter or interrogation energy. This distinction can be obtained by various methods; the present invention utilises a method which achieves the desired result by incorporating means in the label capable of changing the type of the energy, so that the reply energy is of a different type from the interrogate energy. For example in the system described below, the interrogate energy is in the form of acoustic energy while the reply energy is in the form of magnetic field energy.
To be successful the system should and does provide the following features:
a. The labels are passive, with indefinitely long storage life, can be read non destructively, are durable under various environmental and handling conditions, are small and have low manufacturing cost.
b. The labels can have any orientation relative to and considerable distance from the-sensing apparatus, can be in motion, and can be separated from the sensor by optically opaque barriers.
c. The signal is distinguishable from background clutter signals accidentally produced by the environment of the label being interrogated.
A distinction from clutter signals and the encoding of the information is made by choosing a combination of the type of interrogate energy and type of reply energy such that apart from the label, objects found in nature do not possess the necessary combination of characten istics to enable them to receive the type of interrogation energy, to convert this energy to the correct type of reply energy, and then re-radiate this reply energy in the correct way.
In order to assist in understanding the nature of the invention one form thereof is hereinafter described by way of example with reference to the accompanying drawings in which:
FIG. I is a block diagram showing the basic components of the system,
FIG. 2 is an isometric view of a label card for use with the system,
FIGS. 3 and 4 are views in plan and elevation of the label card showing further details, and
FIG. 5 shows one electrode configuration for the resonator incorporated in the label.
FIG. 6 is a block diagram of a pulsed system.
The system to be described is intended for detecting the presence only of a label at a distance of l metre, as might be required for example in a theft-detection system.
The general principleof the system is to provide in the label card a means of receiving energy in acoustic fonn, converting it to electromagnetic energy, and reradiating it as electromagnetic energy or more precisely in this case as magnetic energy. Since the transmitted energy is in acoustic form, and the reply from the label is in a different energy form, namely magnetic, it is thus possible to separate the small label reply from the large transmitted interrogate signal.
The basic components of the system are shown in the block diagram in FIG. 1. The system consists of a. An W, IOOkc/s power oscillator l,
b. A suitable electrical-to-acoustic energy transducer and acoustic antennae unit 2, (For example a barium titanate piezoelectric resonator coupled to the atmosphere by an acoustic horn) which is driven by the power oscillator l and radiates acoustic energy through the air illuminating the volume through-out which it is desired to detect the label,
c. A label 3 described in detail below,
d. A magnetic coil pair 4 connected to a sensitive receiver 5 which detects the reply magnetic field produced by the label when illuminated by the acoustic field. I
The construction of a suitable passive label is shown in the isometric drawing FIG. 2. The label consists of an inner plastic card 6 approximately 2 by 1 inches in size which serves as a protection and supporting substrate for the inner sensitive elements. Cardboard covers 7 and 8 sufficiently thin so as to be essentially transparent to I00 kc/s acoustic radiation, are glued to each side of the plastic card. Further details of the label are shown in FIGS. 3 and 4. In FIG. 3 the plastic card 6 and sensitive element 5 are shown with the cardboard covers 7 and 8 removed.
The acoustic energy is detected by its action in causing resonant vibration of a I00 kc/s flexural-mode resonator 9. In this example the resonator 9 shall be taken as being made of quartz, however any other material having suitable mechanical properties, low acoustic damping, and high piezoelectric coefficients could be used. The flexural vibration mode is used to lower the acoustic impedance level of the resonator and hence to provide a better acoustic impedance match to the air.
Approximate dimensions of the resonator 9 are 1.5 cm long by 0.75 cm wide by 0.010 inch thick. The resonator 9 is set into a cut-out in the plastic card 6, between but not in contact with the cardboard covers 7 and 8. In order to cause minimum damping by its support, it is held at the flexural-mode vibrational nodal-points by four dimples projecting from the sides of the cut-out in the plastic card.
Suitable electrodes are plated onto the resonator 9, one possible electrode configuration being shown in FIG. 5, such that the acoustic vibrational energy in the resonator is converted to electrical energy available between the electrodes 10 and 11 through the piezoelectric properties of the quartz.
This electrical energy, or more precisely the piezoelectric displacement current between electrodes 10 and 11, produces a current through a 10 turn, one square inch area coil 12 connected between electrodes and 11. Coil 12 is conveniently produced on the surface of the plastic card 6 by well-known printed circuitboard techniques. The magnetic field produced by this current flow through coil 12 is then detected by the Helmohltz coil pair 4 and receiver 5, thus enabling the presence of the label to be detected as required.
Calculations show that the power losses occurring in various parts of the overall transmission path from transmitter to receiver are:
a. Acoustic propogation loss from the acoustic transmitter antenna 2 to the acoustic resonator or receiving antenna 9 in the label, 4ldb.
b. Acoustic path absorption between the acoustic transmitting antenna and the label, 3db.
0. Acoustic to electric conversion loss in resonator 9 lOdb.
d. Magnetic propogation loss" between the reactive power available at the resonator 9 output electrodes 10 and 11 to the real power magnetically induced in the receiving coil-pair 4 75db.
The overall transmission path loss is thus l29db.
The noise bandwidth of the receiver is 1000 c/s. Narrower bandwidths are not practical due to the acoustic Doppler shift associated with a person carrying the label through the field. The consequent input noise level of the receiver allowing for a receiver noise figure of 3db is 17ldbW. With a transmitted power of.+ 20 dbW, the input signal level at the receiver is l09dbW. The signal-to-noise ratio at the receiver is thus 62db and the system is not receiver noise limited.
There are certain obvious variations from the design example described in detail above which may be made to suit particular applications.
In particular some of them are:
a. The frequency of operation of the system can be decreased or increased. Decreasing the frequency improves the system signal to noise ratio, however the size of the label is also increased. Increasing the frequency reduces the system signal to noise ratio and decreases the size of the labels. The attenuation of acoustic waves through the air also increases with frequency and this has the important advantage of increasing the discrimination of the system against spurious signals from labels outside the desired detection volume since these signals suffer attenuation due to the longer acoustic propogation path. For example at an operating frequency of 200 KHZ acoustic attenuation in air is 8 db/m. Consequently signals from extraneous labels will be attenuated by 8 db per metre of their distance from the detection volume.
b. Due to reciprocity, the system can also be operated in reverse in the sense that magnetic field energy can be transmitted to the label by the coil-pair 4, converted to and re-radiated as acoustic energy by the label, and this acoustic energy received by the acoustic transducer-antenna 2. This alternative system can have advantages in installations where the atmospheric magnetic field noise energy is higher than the atmospheric acoustic noise energy. Atmospheric acoustic noise energy is normally low at 100 KHZ and increasingly so at higher frequencies due to the acoustic attenuation of the air at these frequencies.
c. Changes may be made in transmitter power level.
(1. As previously stated, due to acoustic Doppler shift, receiver bandwidths of less than 1000 c/s are not possible. Hence system signal to noise ratio cannot be increased by using narrow receiver bandwidths. However for the same average transmitted power, it is possible to obtain an increase in signal to noise ratio effectively equivalent to that achieved by narrowing the receiver bandwidth by pulsing the transmitter and synchronously time gating the receiver. The transmitter pulse width will be determined by the receiver bandwidth, and the pulse repetition frequency by the rate at which a label will be carried through the detection volume. For a constant average transmitted power, the signalto-noise ratio is increased by the ratio of the pulse repetition period divided by the pulse width. For the particular embodiment here described, suitable values are a transmitter pulse length of 6 m/sec, a pulse repetition period of 300 m/sec, with the receiver synchronously gated on for a 3 m/sec period following 3 m/sec after the commencement of each transmitter pulse.
One particular embodiment of such a pulse system is shown in FIG. 6. The principal components are:
l. A IW, IOOkc/s master oscillator 13,
2. A 37 db, l00kc/s gated power amphifier 14 which when gated on by pulse generator 15 delivers W average power, 5 kW peak power to antenna unit 21. Amplifier 14 is gated on for a 6 msec pulse period with a pulse repetition period of 300 in see by pulse generator 15.
3. A suitable electrical-to-acoustic energy transducer and acoustic antenna unit 21, which is driven by power amplifier l4 and radiates acoustic energy through the air illuminating the volume through-out which it is desired to obtect the label.
4. A label 22 identical to label 3 previously described.
5. A magnetic coil pair 24 connected to a sensitive receiver 18 which detects the reply magnetic field produced by the label when illuminated by the acoustic field. The bandwidth of receiver 18 is l000c/s.
6. A gate 19 following receiver 18 which is gated open by pulse generator 17 for a 3 m sec period following 3 in see after the commencement of each transmitter pulse.
7. A final amplifier and detector unit 20 of bandwidth l000c/s which operates an appropriate alarm equipment if the detector output exceeds a certain threshold level during the on-gated period.
8. An as table multivibrator pulse generator 15 which provides a 6 in sec pulse having a 300 in sec pulse repetition rate to gated amplifier 14 plus a trigger pulse to delay generator 16 synchronised with the leading edge of the gating pulse to 14.
9. A monostable multivibrator pulse generator 16 which is triggered by the trigger pulse from 15 and hence provides a second trigger pulse to pulse generator l7 delayed 3 m see after the trigger pulse from l5.
10. A monostable pulse generator 17 which is triggered by the delayed trigger pulse from 16 and whence provides a 3 m sec duration on-gating pulse to receiver gate 19.
e. The use of a pulse system as described in (d) above also enables the system to eliminate spurious returns from labels outside the desired detection volume by taking account of the longer acoustic propogation time to such remote labels. For example for a transmitter pulse length of 6 m sec and a receiver gate interval of 3 m sec as described in (d) above, returns from labels at distances greater than 1.8 m will be eliminated.
The particular embodiment herein described has used in the label a resonator of piezoelectric material which converted received acoustic energy to electrical energy by menas of the piezoelectric effect. It is also possible to use a resonator of magnetostrictive material which converts received acoustic energy to electrical energy by means of the magnetostructive effect. In the latter case the fluctuating magnetic moment induced in the magnetostrictive material would be detected directly by a receiver coil-pair 4 and no transmitting coil 12 would be necessary on the label.
We claim:
1. An electronic surveillance system, comprising transmitter means for transmitting signals having a first form of energy, a passive label for attachment to an article to be placed under surveillance, signal answering means mounted on said label for receiving the signals from said transmitting means and producing signals having a second form of energy and corresponding to the received signals, receiver means responsive to the signals transmitted by said signal answering means for receiving and processing the signals of the second form of energy, control means for defining a surveillance volume, said control means including modulator means coupled to said transmitter means and rendering said receiver means unresponsive to signals from said answering means when the phase of the signals from said answering means relative to the phase of signals from said transmitter means exceeds a given value.
2. A system as in claim 1, wherein said modulator means constrains said transmitter means to produce a series of regular pulses and gate said receiver means synchronously so as to switch on said receiver means at a predetermined time after the commencement of each transmitter pulse and for a predetermined period.
3. A system as in claim 1, wherein one of said transmitter means and said answering means transmit acoustical energy.
4. A system as in claim 1, wherein said transmitter means transmits acoustical energy.
5. A system as in claim 1, wherein said answering means transmits acoustical energy.
6. A system as in claim 4, wherein said answering means transmits electromagnetic energy.
7. A system as in claim 5, wherein said transmitter means transmits electromagnetic energy.
8. A system as in claim 1, wherein said answering means includes second receiver means on said label for receiving the signals of the first form of energy, transducer means on said label coupled to said receiver means for responding to the signals on said second receiver means for forming signals of the second form of energy, and second transmitter means on said label responsive to said transducer means for transmitting the signals of the second form of energy.
9. A system as in claim 1, wherein said answering means includes an electroacoustic resonator on said label.
10. A system as in claim 9, wherein-said resonator is piezoelectric.
11. A system as in claim 9, wherein said resonator is magnetostrictive.
12. An apparatus as in claim 10, wherein said answering means includes an antenna connected to said resonator.
13. A system as in claim 1, wherein said label includes a plastic card having a cutout, said answering means including a piezoelectric resonator adapted to vibrate in a flexural mode, said resonator including electrodes attached to the surface of said piezoelectric resonator, and an antenna formed on the surface of the card connected to said electrodes.
14. A system as in claim 13, wherein said label includes covering means sandwiching the plastic card between them for protecting the resonator and said antenna.
a a: a a: a

Claims (14)

1. An electronic surveillance system, comprising transmitter means for transmitting signals having a first form of energy, a passive label for attachment to an article to be placed under surveillance, signal answering means mounted on said label for receiving the signals from said transmitting means and producing signals having a second form of energy and corresponding to the received signals, receiver means responsive to the signals transmitted by said signal answering means for receiving and processing the signals of the second form of energy, control means for defining a surveillance volume, said control means including modulator means coupled to said transmitter means and rendering said receiver means unresponsive to signals from said answering means when the phase of the signals from said answering means relative to the phase of signals from said transmitter means exceeds a given value.
2. A system as in claim 1, wherein said modulator means constrains said transmitter means to produce a series of regular pulses and gate said receiver means synchronously so as to switch on said receiver means at a predetermined time after the commencement of each transmitter pulse and for a predetermined period.
3. A system as in claim 1, wherein one of said transmitter means and said answering means transmit acoustical energy.
4. A system as in claim 1, wherein said transmitter means transmits acoustical energy.
5. A system as in claim 1, wherein said answering means transmits acoustical energy.
6. A system as in claim 4, wherein said answering means transmits electromagnetic energy.
7. A system as in claim 5, wherein said transmitter means transmits electromagnetic energy.
8. A system as in claim 1, wherein said answering means includes second receiver means on said label for receiving the signals of the first form of energy, transducer means on said label coupled to said receiver means for responding to the signals on said second receiver means for forming signals of the second form of energy, and second transmitter means on said label responsive to said transducer means for transmitting the signals of the second form of energy.
9. A system as in claim 1, wherein said answering means includes an electroacoustic resonator on said label.
10. A system as in claim 9, wherein said resonator is piezoelectric.
11. A system as in claim 9, wherein said resonator is magnetostrictive.
12. An apparatus as in claim 10, wherein said answering means includes an antenna connected to said resonator.
13. A system as in claim 1, wherein said label includes a plastic card having a cutout, said answering means including a piezoelectric resonator adapted to vibrate in a flexural mode, said resonator including electrodes attached to the surface of said piezoelectric resonator, and an antenna formed on the surface of the card connected to said electrodes.
14. A system as in claim 13, wherein said label includes covering means sandwiching the plastic card between them for protecting the resonator and said antenna.
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Cited By (57)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3849633A (en) * 1972-01-04 1974-11-19 Westinghouse Electric Corp Object identifying apparatus
US3914829A (en) * 1973-06-01 1975-10-28 Eaton Corp Releasably attachable clip
US4000488A (en) * 1974-04-19 1976-12-28 Bernard Ephraim Label alarm system
JPS534410A (en) * 1976-07-02 1978-01-17 Masakiyo Negishi Device for transmitting information wave using resonator
USRE29610E (en) * 1973-04-13 1978-04-11 Knogo Corporation Field strength uniformity control system
US4134538A (en) * 1976-03-18 1979-01-16 La Societe Metalimphy Process and apparatus for identification of objects
US4223830A (en) * 1978-08-18 1980-09-23 Walton Charles A Identification system
US4236068A (en) * 1979-03-29 1980-11-25 Walton Charles A Personal identification and signaling system
US4342904A (en) * 1980-10-27 1982-08-03 Minnesota Mining And Manufacturing Company Lightweight ferromagnetic marker for the detection of objects having markers secured thereto
DE3438052A1 (en) * 1984-10-09 1986-04-24 X-Cyte, Inc., Mountain View, Calif. SYSTEM FOR INQUIRING A PASSIVE, PHASE-CODED INFORMATION WITH TRANSPONDER
DE3438051A1 (en) * 1984-10-09 1986-04-24 X-Cyte, Inc., Mountain View, Calif. PASSIVE TRANSPONDER HAVING ACOUSTIC REFLECTORS ON ACOUSTIC SURFACE WAVES
US4600829A (en) * 1984-04-02 1986-07-15 Walton Charles A Electronic proximity identification and recognition system with isolated two-way coupling
WO1986004171A1 (en) * 1985-01-11 1986-07-17 Indala Corporation Identification system
US4604623A (en) * 1983-06-30 1986-08-05 X-Cyte Inc. Surface acoustic wave passive transponder having non-reflective transducers and pads
US4605929A (en) * 1983-06-30 1986-08-12 X-Cyte Inc. Surface acoustic wave passive transponder having optimally-sized transducers
US4620191A (en) * 1983-06-30 1986-10-28 Halvor Skeie Surface acoustic wave passive transponder having parallel acoustic wave paths
US4625207A (en) * 1983-06-30 1986-11-25 X-Cyte Inc. Surface acoustic wave passive transponder having amplitude and phase-modifying surface pads
US4625208A (en) * 1983-06-30 1986-11-25 X-Cyte Inc. Surface acoustic wave passive transponder having acoustic wave reflectors
US4725841A (en) * 1983-06-30 1988-02-16 X-Cyte, Inc. System for interrogating a passive transponder carrying phase-encoded information
US4798175A (en) * 1986-10-09 1989-01-17 Alfa-Laval Agri, Inc. Electronic identification system
WO1989009984A1 (en) * 1988-04-08 1989-10-19 Scientific Generics Limited Antipilferage tags and their use
EP0340015A2 (en) * 1988-04-29 1989-11-02 Esselte Meto International GmbH Antipilferage tags and systems
US5012224A (en) * 1989-12-05 1991-04-30 Sensormatic Electronics Corporation Audible tag for magnetic electronic article surveillance systems
US5021767A (en) * 1987-10-12 1991-06-04 N.V. Nederlandsche Apparatenfabriek Nedap Method and an apparatus for electronically identifying articles moving along a surface
EP0431343A2 (en) * 1989-12-05 1991-06-12 Sensormatic Electronics Corporation Audible tag for magnetic electronic article surveillance systems
EP0615285A2 (en) * 1993-03-11 1994-09-14 Btg International Limited Attaching an electronic circuit to a substrate
US5367289A (en) * 1991-11-27 1994-11-22 Sensormatic Electronics Corporation Alarm tag for an electronic article surveillance system
FR2727549A1 (en) * 1994-11-29 1996-05-31 Verardi Giorgio Adriano Security system for surveillance of goods in warehouse, shop etc.
US5523749A (en) * 1991-04-03 1996-06-04 Integrated Silicon Design Pty. Ltd. Identification system for simultaneously interrogated labels
US5552778A (en) * 1994-11-23 1996-09-03 International Business Machines Corporation Multibit bimorph magnetic tags using acoustic or magnetic interrogation for identification of an object coupled thereto
US5767773A (en) * 1994-07-29 1998-06-16 Kubota Corporation Theft preventive apparatus and radio wave receiving signaling device
US5844484A (en) * 1993-08-31 1998-12-01 Kubota Corporation Theft preventive apparatus having alarm output
US5883575A (en) * 1997-08-12 1999-03-16 Hewlett-Packard Company RF-tags utilizing thin film bulk wave acoustic resonators
US5959532A (en) * 1994-07-29 1999-09-28 Kubota Corporation Theft preventive apparatus and radio wave receiving signaling device
US5986382A (en) * 1997-08-18 1999-11-16 X-Cyte, Inc. Surface acoustic wave transponder configuration
US6060815A (en) * 1997-08-18 2000-05-09 X-Cyte, Inc. Frequency mixing passive transponder
US6107910A (en) * 1996-11-29 2000-08-22 X-Cyte, Inc. Dual mode transmitter/receiver and decoder for RF transponder tags
US6114971A (en) * 1997-08-18 2000-09-05 X-Cyte, Inc. Frequency hopping spread spectrum passive acoustic wave identification device
US6144299A (en) * 1996-07-05 2000-11-07 Integrated Silicon Design Pty. Ltd. Presence and data labels
WO2000075038A1 (en) * 1999-06-02 2000-12-14 Cascades Arnsberg Gmbh Commercial packaging
US6208062B1 (en) 1997-08-18 2001-03-27 X-Cyte, Inc. Surface acoustic wave transponder configuration
US6229442B1 (en) * 2000-03-14 2001-05-08 Motorola, Inc, Radio frequency identification device having displacement current control and method thereof
US6259991B1 (en) 1999-02-10 2001-07-10 X-Cyte Inc. Environmental location system
US20020075152A1 (en) * 2000-12-15 2002-06-20 Paul Nysen Apparatus and method for locating a tagged item
US6535108B1 (en) 1995-08-14 2003-03-18 Intermec Ip Corp. Modulation of the resonant frequency of a circuit using an energy field
US6633226B1 (en) 1997-08-18 2003-10-14 X-Cyte, Inc. Frequency hopping spread spectrum passive acoustic wave identification device
US20040069847A1 (en) * 2002-10-15 2004-04-15 Chester Kolton Electronic article surveillance marker assembly
US6724311B1 (en) 2001-11-09 2004-04-20 B&G Plastics, Inc. Anti-theft hang tag
US6775616B1 (en) 1999-02-10 2004-08-10 X-Cyte, Inc. Environmental location system
US20050007239A1 (en) * 2003-04-30 2005-01-13 U.S.A. As Represented By The Administrator Of The National Aeronautics And Space Administration Magnetic field response measurement acquisition system
US20050270159A1 (en) * 1995-08-14 2005-12-08 Brady Michael J Combination radio frequency identification transponder (RFID Tag) and magnetic electronic article surveillance (EAS) tag
US7123129B1 (en) 1995-08-14 2006-10-17 Intermec Ip Corp. Modulation of the resonant frequency of a circuit using an energy field
US20070115137A1 (en) * 2005-11-21 2007-05-24 Lyon Geoff M Method and apparatus for localization of RFID tags
US20090109005A1 (en) * 2007-10-19 2009-04-30 Usa As Represented By The Administrator Of The National Aeronautics & Space Administration Wireless Damage Location Sensing System
US20120169500A1 (en) * 2010-12-29 2012-07-05 Symbol Technologies, Inc. Radio frequency identification system and method used to perform electronic article surveillance
US8692562B2 (en) 2011-08-01 2014-04-08 The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration Wireless open-circuit in-plane strain and displacement sensor requiring no electrical connections
US9329153B2 (en) 2013-01-02 2016-05-03 United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration Method of mapping anomalies in homogenous material

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4321586A (en) * 1980-08-21 1982-03-23 Knogo Corporation Article theft detection
US4481428A (en) * 1981-05-19 1984-11-06 Security Tag Systems, Inc. Batteryless, portable, frequency divider useful as a transponder of electromagnetic radiation
DE10221484B4 (en) * 2002-05-15 2012-10-11 Hans-Joachim Laue Device for powering a data acquisition and data transfer unit and data acquisition and transfer unit
ES2856828T3 (en) 2015-05-06 2021-09-28 Allflex Australia Pty Ltd Antenna apparatus

Citations (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2774060A (en) * 1953-06-15 1956-12-11 Richard B Thompson Detecting means for stolen goods
US2899546A (en) * 1954-05-25 1959-08-11 hollmann
US3031643A (en) * 1960-05-16 1962-04-24 Nat Company Inc Transmission line fence burglar alarm
US3293595A (en) * 1962-12-29 1966-12-20 Hitachi Ltd Telemetering system
GB1085704A (en) * 1964-10-30 1967-10-04 Nat Res Dev Apparatus for detecting an object
US3389391A (en) * 1967-05-05 1968-06-18 Miner S Keeler Vehicle identification responder
US3399405A (en) * 1966-03-29 1968-08-27 Rca Corp Vehicle identifier system
US3432852A (en) * 1967-06-19 1969-03-11 Sylvania Electric Prod Transponder having improved isolation
US3493955A (en) * 1968-04-17 1970-02-03 Monere Corp Method and apparatus for detecting the unauthorized movement of articles
US3500373A (en) * 1966-05-06 1970-03-10 Nat Bank Of North America The Method and apparatus for article theft detection
US3521280A (en) * 1969-01-16 1970-07-21 Gen Res Corp Coded labels
US3577136A (en) * 1967-08-04 1971-05-04 Security Systems Inc Short-range signaling system
US3631442A (en) * 1968-03-22 1971-12-28 Robert E Fearon Anti-shoplifting system

Family Cites Families (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE406240C (en) * 1922-12-06 1924-11-14 Atlas Werke Akt Ges Method for measuring distances at sea through the time difference between the transmission of a signal on a ship and the arrival of a response signal
DE704878C (en) * 1933-08-31 1941-04-09 Rca Corp Wireless signaling device to indicate certain points
NL91659C (en) * 1950-05-13
DE1058580B (en) * 1956-08-16 1959-06-04 Philips Patentverwaltung Method for the identification of a moving object from a plurality of similar objects by means of a radar system
DE1178331B (en) * 1957-03-04 1964-09-17 Bendix Corp Method for the selection of amplitudes and arrangement for measuring the distance by reflecting sound waves, in particular for acoustic height measurement
US3079599A (en) * 1961-08-07 1963-02-26 James W Caspers Aural detection system
DE1239593B (en) * 1963-11-16 1967-04-27 Fritz Steiner Dr Ing Method for indicating the risk of vehicle collisions on motorways and arrangement for carrying out the method
SE321883B (en) * 1965-03-05 1970-03-16 A Minasy
FR1547366A (en) * 1965-11-06 1968-11-29 Inst Francais Du Petrole At-sea beaconing and locating system for a floating installation or an underwater vehicle
NO126975B (en) * 1967-03-30 1973-04-16 John Welsh

Patent Citations (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2774060A (en) * 1953-06-15 1956-12-11 Richard B Thompson Detecting means for stolen goods
US2899546A (en) * 1954-05-25 1959-08-11 hollmann
US3031643A (en) * 1960-05-16 1962-04-24 Nat Company Inc Transmission line fence burglar alarm
US3293595A (en) * 1962-12-29 1966-12-20 Hitachi Ltd Telemetering system
GB1085704A (en) * 1964-10-30 1967-10-04 Nat Res Dev Apparatus for detecting an object
US3399405A (en) * 1966-03-29 1968-08-27 Rca Corp Vehicle identifier system
US3500373A (en) * 1966-05-06 1970-03-10 Nat Bank Of North America The Method and apparatus for article theft detection
US3389391A (en) * 1967-05-05 1968-06-18 Miner S Keeler Vehicle identification responder
US3432852A (en) * 1967-06-19 1969-03-11 Sylvania Electric Prod Transponder having improved isolation
US3577136A (en) * 1967-08-04 1971-05-04 Security Systems Inc Short-range signaling system
US3631442A (en) * 1968-03-22 1971-12-28 Robert E Fearon Anti-shoplifting system
US3493955A (en) * 1968-04-17 1970-02-03 Monere Corp Method and apparatus for detecting the unauthorized movement of articles
US3521280A (en) * 1969-01-16 1970-07-21 Gen Res Corp Coded labels

Cited By (79)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3849633A (en) * 1972-01-04 1974-11-19 Westinghouse Electric Corp Object identifying apparatus
USRE29610E (en) * 1973-04-13 1978-04-11 Knogo Corporation Field strength uniformity control system
US3914829A (en) * 1973-06-01 1975-10-28 Eaton Corp Releasably attachable clip
US4000488A (en) * 1974-04-19 1976-12-28 Bernard Ephraim Label alarm system
US4134538A (en) * 1976-03-18 1979-01-16 La Societe Metalimphy Process and apparatus for identification of objects
JPS534410A (en) * 1976-07-02 1978-01-17 Masakiyo Negishi Device for transmitting information wave using resonator
US4223830A (en) * 1978-08-18 1980-09-23 Walton Charles A Identification system
US4236068A (en) * 1979-03-29 1980-11-25 Walton Charles A Personal identification and signaling system
US4342904A (en) * 1980-10-27 1982-08-03 Minnesota Mining And Manufacturing Company Lightweight ferromagnetic marker for the detection of objects having markers secured thereto
US4625207A (en) * 1983-06-30 1986-11-25 X-Cyte Inc. Surface acoustic wave passive transponder having amplitude and phase-modifying surface pads
US4725841A (en) * 1983-06-30 1988-02-16 X-Cyte, Inc. System for interrogating a passive transponder carrying phase-encoded information
US4625208A (en) * 1983-06-30 1986-11-25 X-Cyte Inc. Surface acoustic wave passive transponder having acoustic wave reflectors
US4620191A (en) * 1983-06-30 1986-10-28 Halvor Skeie Surface acoustic wave passive transponder having parallel acoustic wave paths
US4604623A (en) * 1983-06-30 1986-08-05 X-Cyte Inc. Surface acoustic wave passive transponder having non-reflective transducers and pads
US4605929A (en) * 1983-06-30 1986-08-12 X-Cyte Inc. Surface acoustic wave passive transponder having optimally-sized transducers
US4600829A (en) * 1984-04-02 1986-07-15 Walton Charles A Electronic proximity identification and recognition system with isolated two-way coupling
DE3438052A1 (en) * 1984-10-09 1986-04-24 X-Cyte, Inc., Mountain View, Calif. SYSTEM FOR INQUIRING A PASSIVE, PHASE-CODED INFORMATION WITH TRANSPONDER
DE3438051A1 (en) * 1984-10-09 1986-04-24 X-Cyte, Inc., Mountain View, Calif. PASSIVE TRANSPONDER HAVING ACOUSTIC REFLECTORS ON ACOUSTIC SURFACE WAVES
WO1986004171A1 (en) * 1985-01-11 1986-07-17 Indala Corporation Identification system
US4818855A (en) * 1985-01-11 1989-04-04 Indala Corporation Identification system
US4798175A (en) * 1986-10-09 1989-01-17 Alfa-Laval Agri, Inc. Electronic identification system
US5021767A (en) * 1987-10-12 1991-06-04 N.V. Nederlandsche Apparatenfabriek Nedap Method and an apparatus for electronically identifying articles moving along a surface
WO1989009984A1 (en) * 1988-04-08 1989-10-19 Scientific Generics Limited Antipilferage tags and their use
EP0341828A1 (en) * 1988-04-08 1989-11-15 Esselte Meto International GmbH Antipilferage tags and their use
EP0340015A3 (en) * 1988-04-29 1991-06-05 Esselte Meto International GmbH Antipilferage tags and systems
EP0340015A2 (en) * 1988-04-29 1989-11-02 Esselte Meto International GmbH Antipilferage tags and systems
EP0431343A3 (en) * 1989-12-05 1992-04-08 Sensormatic Electronics Corporation Audible tag for magnetic electronic article surveillance systems
EP0431343A2 (en) * 1989-12-05 1991-06-12 Sensormatic Electronics Corporation Audible tag for magnetic electronic article surveillance systems
US5012224A (en) * 1989-12-05 1991-04-30 Sensormatic Electronics Corporation Audible tag for magnetic electronic article surveillance systems
US5793305A (en) * 1991-04-03 1998-08-11 Turner; Leigh Holbrook Article sorting system
US5523749A (en) * 1991-04-03 1996-06-04 Integrated Silicon Design Pty. Ltd. Identification system for simultaneously interrogated labels
US5367289A (en) * 1991-11-27 1994-11-22 Sensormatic Electronics Corporation Alarm tag for an electronic article surveillance system
EP0615285A2 (en) * 1993-03-11 1994-09-14 Btg International Limited Attaching an electronic circuit to a substrate
EP0615285A3 (en) * 1993-03-11 1996-09-18 Csir Attaching an electronic circuit to a substrate.
US5844484A (en) * 1993-08-31 1998-12-01 Kubota Corporation Theft preventive apparatus having alarm output
US5959532A (en) * 1994-07-29 1999-09-28 Kubota Corporation Theft preventive apparatus and radio wave receiving signaling device
US5767773A (en) * 1994-07-29 1998-06-16 Kubota Corporation Theft preventive apparatus and radio wave receiving signaling device
US6020819A (en) * 1994-07-29 2000-02-01 Kubota Corporation Radio wave receiving signaling device
US5552778A (en) * 1994-11-23 1996-09-03 International Business Machines Corporation Multibit bimorph magnetic tags using acoustic or magnetic interrogation for identification of an object coupled thereto
FR2727549A1 (en) * 1994-11-29 1996-05-31 Verardi Giorgio Adriano Security system for surveillance of goods in warehouse, shop etc.
US20050270159A1 (en) * 1995-08-14 2005-12-08 Brady Michael J Combination radio frequency identification transponder (RFID Tag) and magnetic electronic article surveillance (EAS) tag
US7123129B1 (en) 1995-08-14 2006-10-17 Intermec Ip Corp. Modulation of the resonant frequency of a circuit using an energy field
US6535108B1 (en) 1995-08-14 2003-03-18 Intermec Ip Corp. Modulation of the resonant frequency of a circuit using an energy field
US6144299A (en) * 1996-07-05 2000-11-07 Integrated Silicon Design Pty. Ltd. Presence and data labels
US7741956B1 (en) 1996-11-29 2010-06-22 X-Cyte, Inc. Dual mode transmitter-receiver and decoder for RF transponder tags
US6531957B1 (en) * 1996-11-29 2003-03-11 X-Cyte, Inc. Dual mode transmitter-receiver and decoder for RF transponder tags
US6950009B1 (en) 1996-11-29 2005-09-27 X-Cyte, Inc. Dual mode transmitter/receiver and decoder for RF transponder units
US6107910A (en) * 1996-11-29 2000-08-22 X-Cyte, Inc. Dual mode transmitter/receiver and decoder for RF transponder tags
US5883575A (en) * 1997-08-12 1999-03-16 Hewlett-Packard Company RF-tags utilizing thin film bulk wave acoustic resonators
US7132778B1 (en) 1997-08-18 2006-11-07 X-Cyte, Inc. Surface acoustic wave modulator
US6114971A (en) * 1997-08-18 2000-09-05 X-Cyte, Inc. Frequency hopping spread spectrum passive acoustic wave identification device
US6208062B1 (en) 1997-08-18 2001-03-27 X-Cyte, Inc. Surface acoustic wave transponder configuration
US6611224B1 (en) * 1997-08-18 2003-08-26 X-Cyte, Inc. Backscatter transponder interrogation device
US6633226B1 (en) 1997-08-18 2003-10-14 X-Cyte, Inc. Frequency hopping spread spectrum passive acoustic wave identification device
US6060815A (en) * 1997-08-18 2000-05-09 X-Cyte, Inc. Frequency mixing passive transponder
US7023323B1 (en) 1997-08-18 2006-04-04 X-Cyte, Inc. Frequency hopping spread spectrum passive acoustic wave identification device
US5986382A (en) * 1997-08-18 1999-11-16 X-Cyte, Inc. Surface acoustic wave transponder configuration
US6259991B1 (en) 1999-02-10 2001-07-10 X-Cyte Inc. Environmental location system
US6775616B1 (en) 1999-02-10 2004-08-10 X-Cyte, Inc. Environmental location system
WO2000075038A1 (en) * 1999-06-02 2000-12-14 Cascades Arnsberg Gmbh Commercial packaging
US6229442B1 (en) * 2000-03-14 2001-05-08 Motorola, Inc, Radio frequency identification device having displacement current control and method thereof
US6995654B2 (en) 2000-12-15 2006-02-07 X-Cyte, Inc. Apparatus and method for locating a tagged item
US20020075152A1 (en) * 2000-12-15 2002-06-20 Paul Nysen Apparatus and method for locating a tagged item
US6724311B1 (en) 2001-11-09 2004-04-20 B&G Plastics, Inc. Anti-theft hang tag
US20040069847A1 (en) * 2002-10-15 2004-04-15 Chester Kolton Electronic article surveillance marker assembly
US7086593B2 (en) * 2003-04-30 2006-08-08 The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration Magnetic field response measurement acquisition system
US20050007239A1 (en) * 2003-04-30 2005-01-13 U.S.A. As Represented By The Administrator Of The National Aeronautics And Space Administration Magnetic field response measurement acquisition system
US7159774B2 (en) * 2003-04-30 2007-01-09 The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration Magnetic field response measurement acquisition system
US20060124740A1 (en) * 2003-04-30 2006-06-15 U.S.A. As Represented By The Administrator Of The National Aeronautics And Space Administration Magnetic field response measurement acquisition system
WO2007061836A2 (en) * 2005-11-21 2007-05-31 Hewlett-Packard Development Company, L.P. Method and apparatus for localization of rfid tags
WO2007061836A3 (en) * 2005-11-21 2008-02-21 Hewlett Packard Development Co Method and apparatus for localization of rfid tags
US20070115137A1 (en) * 2005-11-21 2007-05-24 Lyon Geoff M Method and apparatus for localization of RFID tags
US9285471B2 (en) 2005-11-21 2016-03-15 Hewlett-Packard Development Company, L.P. Method and apparatus for localization of RFID tags
US20090109005A1 (en) * 2007-10-19 2009-04-30 Usa As Represented By The Administrator Of The National Aeronautics & Space Administration Wireless Damage Location Sensing System
US8167204B2 (en) * 2007-10-19 2012-05-01 The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration Wireless damage location sensing system
US20120169500A1 (en) * 2010-12-29 2012-07-05 Symbol Technologies, Inc. Radio frequency identification system and method used to perform electronic article surveillance
US8497776B2 (en) * 2010-12-29 2013-07-30 Symbol Technologies, Inc. Radio frequency identification system and method used to perform electronic article surveillance
US8692562B2 (en) 2011-08-01 2014-04-08 The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration Wireless open-circuit in-plane strain and displacement sensor requiring no electrical connections
US9329153B2 (en) 2013-01-02 2016-05-03 United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration Method of mapping anomalies in homogenous material

Also Published As

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FR2038184A1 (en) 1971-01-08
BR7017852D0 (en) 1973-04-17
CH516853A (en) 1971-12-15
LU60653A1 (en) 1971-06-14
SE394042B (en) 1977-05-31
DE2015295A1 (en) 1970-10-15
NL7004748A (en) 1970-10-06
IL34185A0 (en) 1970-05-21
BE748054A (en) 1970-09-28
DE2015295C2 (en) 1983-10-27
GB1292380A (en) 1972-10-11

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