US3706094A - Electronic surveillance system - Google Patents

Electronic surveillance system Download PDF

Info

Publication number
US3706094A
US3706094A US14607A US3706094DA US3706094A US 3706094 A US3706094 A US 3706094A US 14607 A US14607 A US 14607A US 3706094D A US3706094D A US 3706094DA US 3706094 A US3706094 A US 3706094A
Authority
US
United States
Prior art keywords
propagating
sensing means
signals
sensing
signal
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US14607A
Inventor
Peter Harold Cole
Richard Vaughan
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.)
Individual
Original Assignee
Individual
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 Individual filed Critical Individual
Application granted granted Critical
Publication of US3706094A publication Critical patent/US3706094A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • GPHYSICS
    • G08SIGNALLING
    • G08BSIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B13/00Burglar, theft or intruder alarms
    • G08B13/22Electrical actuation
    • G08B13/24Electrical actuation by interference with electromagnetic field distribution
    • G08B13/2402Electronic 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
    • G08B13/2405Electronic 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
    • G08B13/2422Electronic 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
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01SRADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/74Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems
    • G01S13/75Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems using transponders powered from received waves, e.g. using passive transponders, or using passive reflectors
    • G01S13/751Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems using transponders powered from received waves, e.g. using passive transponders, or using passive reflectors wherein the responder or reflector radiates a coded signal
    • G01S13/755Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems using transponders powered from received waves, e.g. using passive transponders, or using passive reflectors wherein the responder or reflector radiates a coded signal using delay lines, e.g. acoustic delay lines
    • GPHYSICS
    • G08SIGNALLING
    • G08BSIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B13/00Burglar, theft or intruder alarms
    • G08B13/22Electrical actuation
    • G08B13/24Electrical actuation by interference with electromagnetic field distribution
    • G08B13/2402Electronic 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
    • G08B13/2428Tag details
    • G08B13/2431Tag circuit details
    • GPHYSICS
    • G08SIGNALLING
    • G08BSIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B13/00Burglar, theft or intruder alarms
    • G08B13/22Electrical actuation
    • G08B13/24Electrical actuation by interference with electromagnetic field distribution
    • G08B13/2402Electronic 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
    • G08B13/2428Tag details
    • G08B13/2437Tag layered structure, processes for making layered tags
    • GPHYSICS
    • G08SIGNALLING
    • G08BSIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B13/00Burglar, theft or intruder alarms
    • G08B13/22Electrical actuation
    • G08B13/24Electrical actuation by interference with electromagnetic field distribution
    • G08B13/2402Electronic 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
    • G08B13/2465Aspects related to the EAS system, e.g. system components other than tags
    • G08B13/2468Antenna in system and the related signal processing
    • G08B13/2471Antenna signal processing by receiver or emitter
    • GPHYSICS
    • G08SIGNALLING
    • G08BSIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B13/00Burglar, theft or intruder alarms
    • G08B13/22Electrical actuation
    • G08B13/24Electrical actuation by interference with electromagnetic field distribution
    • G08B13/2402Electronic 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
    • G08B13/2465Aspects related to the EAS system, e.g. system components other than tags
    • G08B13/2468Antenna in system and the related signal processing
    • G08B13/2477Antenna or antenna activator circuit

Definitions

  • a passive label is interrogated by transmitting electromagnetic energy to the label and receiving electromagnetic energy from the label.
  • Time delay means are provided in the label, preferably by utilization of surface acoustic waves, so that the returned energy is transmitted from the label after the interrogation energy has ceased.
  • the label includes a substrate of piezoelectric material having coded information thereon, and serving to receive electromagnetic energy, convert it to acoustic energy, store the converted energy for a suitable time, reconvert the stored energy to electromagnetic energy and to transmit the electromagnetic energy to the receiver.
  • INVENTORS PETER HAROLD -co
  • the present invention utilizes a method which achieves the desired result, incorporating time delay in the label preferably by utilization of surface acoustic waves so that the reply energy is transmitted after the interrogation energy has died away.
  • the facilities offered by the present invention provide for the open or secret interrogation by radio waves of coded information from prepared passive labels by a remote sensing apparatus.
  • Some of the many applications are: a. Automatic sorting of passengers luggage in airline terminals. b. Sorting and routing of letters and parcels in postal services. c. Identification, accreditation and location of personnel in security installations, factories, hospitals or military theatres. d. Ticketing of passengers in transportation systems. e. 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 unauthorized passage of such tagged items through each exit will be detected.
  • a system according to the invention may be set up to provide the following features:
  • the system returns several, or even many, binary digits (bits) of information to the interrogator.
  • a social security number for example requires 30 bits of information.
  • the labels containing the coded information 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 coded signal is distinguishable from background clutter signals accidently produced by the environment of the label being interrogated.
  • the encoding of the information on the label can be performed by simple means at the time the label is put into service. Users of the system need stock only blank labels rather than a complete set of labels with all possible codes.
  • a system for the encoding of 10 bits of information in a plastic card 5 cm g 8 cm X 1 mm the card to be sensed from a distance of 3 meters.
  • the card may have any orientation and can be moving at a speed of up to 1 meter per sec. in any direction, as may be required for example in a baggage sorting operation.
  • the general principle of a system according to this fon'n of the invention is to provide in the label card a means of receiving electromagnetic energy, converting it to acoustic form, storing it for a suitable time, reconverting it to electromagnetic energy for retransmission in a coded form which then contains the information encoded in the label.
  • a further form of the invention is also described in which a carrier frequency of 10 MHz is used.
  • FIG. 1 is a block diagram of the system as a whole
  • FIG. 2 is a similar diagram of the transmitter unit
  • FIG. 3 is a curve showing the passband of the output filter
  • FIG. 4 is an isometric view of a label for use with the system
  • FIG. 5 is a view of a portion of the label to an enlarged scale
  • FIG. 6 shows details of one of the array elements of the label
  • FIG. '7 is a diagram showing the sequence of pulses arriving at the receiver
  • FIG. 8 is a block diagram of the receiver
  • FIG. 9 is a block diagram of the signal processor
  • FIGS. 10 and 11 show modified forms of array structures for labels intended for simplified applications
  • FIG. 12 is a block diagram of the system as a whole
  • FIG. 13 is a diagram of the antennas used in the transmitter and receiver units
  • FIG. 14 is a circuit diagram of the master oscillator for the transmitter unit (and also of the local oscillator for the receiver unit),
  • FIG. 15 is a circuit diagram of a gated amplifier used in the transmitter unit (and also of a gated amplifier used in the receiver unit),
  • FIG. 16 is a circuit diagram of one of two low power amplifiers used in the transmitter unit
  • FIG. 17 is a circuit diagram of a dynamic range expanding and power level setting unit used in the transmitter.
  • FIG. 18 is a circuit diagram of a medium power amplifier used in the transmitter unit
  • FIG. 19 is a circuit diagram of the transmitter output amplifier
  • FIG. 20 is a diagram of the coded label
  • FIG. 21 is a diagram of the surface acoustic delay line
  • FIG. 22 is a circuit diagram of the receiver preamplifier
  • FIG. 23 is a circuit diagram of a gated rf amplifier used in the receiver
  • FIG. 24 is a circuit diagram of a balanced mixer and balance to unbalance amplifier used in the receiver
  • FIG. 25 is a circuit diagram of a narrow band amplifier in the output of the receiver.
  • the basic components of the system are shown in block diagram in FIG. 1.
  • the system contains a transmitter of electromagnetic waves 1, an information carrying label 2, a receiver of electromagnetic waves 3, all of which are operated simultaneously.
  • a customer encoding device 4 which is used to encode the desired information on to previously blank stock labels prior to their use in the system.
  • the transmitter employs standard UHF and microwave technology.
  • the principle components and specifications are:
  • a low frequency pulse oscillator 8 producing rectangular pulses of duration 100 nanoseconds, rise time 5 nanoseconds, pulse repetition frequency KHZ, provided with a main output 9 and a reference output 10, as shown.
  • a pulsed power amplifier 11 with center frequency 915 MHZ, band width 50 MHZ, peak output power 100 watts, pulse length 100 nanoseconds, pulse repetition frequency 10 KHZ, and on/off ratio in excess of 150 decibels.
  • An output filter 12 with a passband shown in FIG. 3, to restrict the frequency components of the output radiation to those allowed by the statutory authority.
  • the position of the carrier in relation to the passband of FIG. 3 has been chosen to provide vestigial sideband modulation.
  • a microwave antenna system 13 which illuminates the area containing the information label to be read.
  • An antenna gain of 6 decibels is chosen in this design. Higher figures can be used to advantage and without difficulty.
  • microwave adsorbing materials 14 in the main lobe of the transmitter antenna to avoid electromagnetic echo signals from distant objects.
  • FIG. 4 The construction of a suitable information carrying passive label is shown in the isometric drawing FIG. 4.
  • the outer section is in the form of a plastic or cardboard card 15, which serves as a protection for the inner sensitive elements 16.
  • Printed or punched information 17 can be included on the card if this is convenient for other purposes.
  • the part of the card which interacts with the sensing system is a microwave antenna system 18, one form of which might be a lumped loaded loop for omni directional response as shown. This antenna is connected via a transmission line 19, to the part of the card on which the information is encoded. This latter element is shown in more detail in FIG. 5.
  • the coding portion of the card consists first of a piezoelectric substrate 20, in this example a plate of single crystal quartz is used. Other materials can be used providing that they singly or in combination provided a high piezoelectrics co-efficient transducer region and a low acoustic loss propogation region.
  • the information is encoded on the substrate in the form of the spatial pattern formed by the conducting electrode array deposited on the substrate surface. Details of the space pattern appropriate to the ten bit binary code 1 10100111 1 are shown in FIG. 5, and the details of one of the array elements are shown in FIG. 6.
  • the array contains an end element 22, consisting of 26 electrodes and a set of coding elements 23, consisting of 16 electrodes. Alternate electrodes are connected to different conductors of the transmission line 19, from the microwave antenna 18.
  • the spacing of the electrodes in this example is approximately 2pm, the precise distance is adjusted to be one-half of a wave length of a surface electroacoustic wave at the operating center frequency of 9 15 MHZ.
  • connection or disconnection of an array element 23, at a given point on the main transmission line 19 signifies respectively a one or a zero binary digit.
  • all cards are manufactured with a full sequency of ones by having all array elements present.
  • the required code is impressed on the card by the user by severing the connections of an appropriate number of array elements from the main transmission line.
  • Labels may, however, be coded during manufacture by omitting the electrode structure from one or more elements or by not connecting them to the transmission line.
  • the card receives the pulsed electromagnetic energy via its antenna 18, and energizes the entire array along the transmission line 19.
  • the various elements of the array launch surface electroacoustic waves along the piezoelectric substrate in the direction of the transmission line. After a time equal to the propogation time for such waves along the blank portion 24, of the transmission line, the electroacoustic waves are reconverted to electromagnetic energy and reradiate electromagnetic waves via the antenna 18. This reradiated energy is picked up and processed by the receiver 3.
  • FIG. 7 A diagram of the sequence of pulses which arrive at the receiver is shown in FIG. 7.
  • the sequence consists of a large amplitude pulse 25, arriving directly from the transmitter a series of unwanted interference pulses 26, resulting from propogation of electroacoustic pulses between various elements of the coding array, followed by the wanted set of pulses 27, which result from propogation of electroacoustic pulses between the end element 22, and the set of coding elements 23. It is this last group of pulses which are free of interference and contain the coded information, which are processed by the receiver in the manner described below:
  • the various components of the receiver 3, are shown in block diagram form in FIG. 8.
  • the directional antenna 28 is similar in design to the transmitter antenna 13.
  • a band pass filter 29 serves to reject possible radio frequency interference from sources unrelated to this system.
  • a limiting device 30 protects the receiver from saturation or overload from the large amplitude transmitted pulse.
  • a low noise (noise figure less than 6 db) pre-amplifier 31, and post-amplifier fitted with automatic gain control 32, provide an amplified received pulse sequence to the signal processing unit 33. Details of the design of the signal processing unit capable of providing for maximum sensitivity, using the technique of synchronous detection, are given below.
  • a block diagram of the signal processor appears in F IG. 9.
  • the amplified pulse sequence from the receiver enters at 34, is divided into two signals, fed via buffer amplifiers 35, to the synchronous detectors 36 and 37.
  • the reference drive for detector 36 is obtained from the transmitter master oscillator signal which enters at 7.
  • the reference drive for detector 37 is derived from the same reference via the "/2 phase shift network 38.
  • the detectors 36 and 37 perform respectively in phase and quadrature phase detection of the received signal with respect to the transmitter master oscillator.
  • the detected signals are fed to buffer amplifiers 39, from each of which outputs, in the present example, are available.
  • Each of the 10 outputs from these buffer amplifiers is then fed to one of 20 gating circuits 40, only two of which are shown.
  • the gates are controlled by a count down circuit 41, which is synchronized with the transmitted pulse via a signal brought from the transmitter through the reference line 10.
  • the count down circuit has ten output pulses each with a width equal to the transmitter pulse, 100 nsec in this example.
  • the various output pulses have different time delays from the transmitted pulse, each adjusted to the delay expected from one or another of the pulses in the received pulse train 27.
  • the outputs of the various gates 40 are filtered in low pass filters 42 which set the effective noise band width of the system.
  • the outputs of these filters are fed through bufi'er amplifiers (not shown) to the square law devices 43, which produce a (unidirectional) output proportional to the square of the input signal over the designed operating range.
  • the outputs of the above described signal processor can be fed to a wide range of logic circuits, not shown in FIG. 9, to perform the various command identification and sorting tasks required of the overall system.
  • logic circuits not shown in FIG. 9, to perform the various command identification and sorting tasks required of the overall system.
  • the design of such logic circuits follows well established procedures.
  • Electromagnetic propogation loss from transmitter antenna to label antenna 33 db.
  • Electromagnetic to electroacoustic conversion loss 38 db.
  • Electroacoustic propogation loss 2db.
  • Electroacoustic to electromagnetic conversion loss 31 db.
  • Electromagnetic propogation loss from label antenna to receiver antenna 33 db.
  • the overall transmission path loss is 137 db.
  • the noise band width of the receiver is determined by the low pass filter 42, which follows the synchronous demodulation and is set to l KHZ.
  • the input noise level of the receiver allowing for 6 db. noise figure and 1 db loss in the band pass filter 29, is --l 67 db W.
  • the input signal level at the receiver is l07 db W.
  • the signal to noise ratio at the receiver is thus db and the system is not receiver noise limited.
  • the system depends for its success on distinguishing the acoustically delayed echos from background clutter produced by direct electromagnetic echo. Since the acoustic time delay before retransmission of the coded pulse sequence is, in this example, in excess of 3 microseconds, the relevant electromagnetic echos will be via propogation paths of lengths in excess of 900 meters, and will in most circumstances be suitably small. Problems which may arise can be eliminated by proper use of the antenna patterns of the transmitter and receiver, in conjunction with suitably placed natural or artificial microwave adsorbers. Calculations have shown that direct echo can be reduced well below the acoustic echo level if the resultant enclosure has a Q factor of less than 100, and the system is then not limited by background clutter.
  • Pulse length and pulse repetition rate may be varied to make a longer or more compact code possible.
  • Changes may be made in transmitter power level and the characteristics of transmitter, receiver and label antennas, including use of duplexing, to provide various microwave propogation systems.
  • a range of substrate materials can be used for the acoustic propogation, including piezoelectric materials whose acoustic loss is not necessarily low, deposited on low acoustic loss substrates. Magnetostriction devices may also used in place of or in conjunction with the piezoelectric materials to accomplish the electroacoustic conversion.
  • the transducer array structure can be modified in number and shape of elements, and in the manner of its interconnection to the transmission line.
  • f. Coding methods other than the simple binary, such as pulse height, width or position, can be used.
  • the disposition of the various elements in the card, and the size shape and nature of the card can be varied to suit particular applications.
  • the code and array structure can be simplified to fewer, or even one, element for simplified applications such as object surveillance as described in application (e) of section 1.
  • Use is made of a surface wave reflector, or a rat race propogation path, in this case.
  • Two such possible simplified structures are shown diagrammatically in FIG. 10 and FIG. 11.
  • use is made of a surface wave reflector 46, which returns the acoustic pulse to the single acousticwave launching and receiving array 47.
  • FIG. 10 Two such possible simplified structures are shown diagrammatically in FIG. 10 and FIG. 11.
  • FIG. 10 use is made of a surface wave reflector 46, which returns the acoustic pulse to the single acousticwave launching and receiving array 47.
  • the surface wave is constrained by suitable groves 48, etched in the surface of the quartz substrate to propogate around a circular, or rat-race", propogation path so as to again return to the single acousticwave launching and receiving array after a suitable time delay.
  • FIGS. 12 to 21 a version which operates at a carrier frequency of MHz and provides for a return signal carrying five bits of information.
  • the basic components of this realization of the system are shown in FIG. 12.
  • the system is controlled by a pulse repetition frequency generator 50, (of which no schematic is given because it is a commercial instrument), which sends pulses at a 50 KPPS rate to the pulse width generator 51 (another commercial instrument); the output pulses being 0.5 ,1. sec. long.
  • the gated amplifier 52 shown in FIG. 15 is controlled by the pulse width generator, and feeds 0.5 p. sec. pulses of radio frequency energy which have been generated by master oscillator 53, shown in FIG. 14, to the series of low power amplifiers 54 and 55 shown in FIG. 16.
  • the amplified gated radio-frequency pulses are expanded in dynamic range by range expander and level setting circuits 56, shown in FIG.
  • the transmitter antenna is in the form of a shielded square magnetic dipole of scale 12 inches of a form of construction well known for aircraft direction finder loops and is loaded to a Q factor of 5. Details of the transmitter antenna are shown in FIG. 13, and schematic diagrams of many of the transmitter circuits are provided in FIGS. 14 to 19 inclusive.
  • FIG. 20 shows the label used, consisting of a printed-circuit magnetic loop antenna 71 on a 6 inches X 4 inches epoxy-glass card 72 tuned to resonate at 10 Mc/s by a fixed capacitor 73 and loaded by a fixed resistor 74 to a Q factor of 5.
  • the coding portion of the label is again a quartz substrate 5 cm X 2.5 cm X 2 cm thickness, carrying the conducting electrode pattern 75 shown in FIG. 21, which returns the five bit binary code 11111, connected to the antenna 71 as shown in FIG. 20.
  • the electrode pattern 75 is constructed and operates in a manner similar to that described in connection with the first embodiment of the invention. It will be noted however that the dimensions are quite different due to the use of a lower carrier frequency. In the electrode pattern 75 the spacing between individual electrodes of the pattern is 0.1625 mm. After a delay of approximately 6 p. sec. following the completion of the transmitter pulse, the coded reply signal is retransmitted by the label and a portion of the reply energy is received by the receiver antenna 61. The output signal for the receiver antenna is initially amplified by lownoise receiver amplifier 62, shown in FIG. 22, which has been specially designed to provide rapid recovery from overload, and is then passed to gated amplifier 63, shown in FIG. 23.
  • the gated amplifier 63 is one of two gated amplifiers 63 and 64 which are controlled in the receiver from the pulse repetition frequency generator 50 via delay generator 65 and pulse width generator 66.
  • the function of delay generator 65 and pulse width generator 66 is to open the receiver gate at a period of time so delayed with respect to the time of the transmitter pulse as to correspond to the detection of a particular bit in the reply code. Varying the amount of delay provided by delay generator 65 allows various bits in the reply coded to be detected separately.
  • the further operation of the receiver is concerned with the balanced mixer 67, shown in FIG. 24, which receives the gated signals both from the low noise amplifier 62 and a highly stable local oscillator 68 and produces at its output the difference frequency resulting from the mixing of the two signals.
  • This frequency is equal to the difference in frequency between master oscillator 53 and local oscillator 68. It is important to the operation of the overall system that master oscillator 53 and local oscillator 68 should have a closely controlled frequency to maintain the difference frequency within the passband of the narrow band tuned amplifier 68a, shown in FIG. 25.
  • This difference frequency must be suitably chosen and must lie sufficiently about zero frequency (that is DC) to avoid l /f or flicker noise, but below the pulse repetition frequency generated by pulse repetition frequency generator 50, such that no mixing products of the gate transients of gates 63 and 64 will contaminate or add noise to the system output.
  • the output from tuned amplifier 68a is fed to a nonlinear detector 69 which measures the magnitude of the difference frequency signal from tuned amplifier 68a and registers a l as being received from label 60 for the particular bit position then under examination if this signal suitably exceeds the system noise level.
  • An electronic surveillance system comprising transmitter means for transmitting electromagnetic signals, label means adapted for attachment to an article under surveillance for receiving a signal from said transmitter means and for retransmitting a reply, and receiver means for receiving and processing the reply; said label means including signal propagating means responsive to the signal from the transmitter for propagating the transmitted signal along a path at a rate slower than electromagnetic propogation, a plurality of sensing means mounted at coded locations along the path of said propagating means each for sensing the presence of a propagated signal at the location so that said sensing means together sense each signal sequentially in a given coded time order, an energy carrier means coupled to each of said sensing means for retransmitting the sequence of signals in the order they are sensed by said sensing means as the reply, said carrier means forming a signal path between said sensing means so that signals can move faster than the propagation rate of said propagating means.
  • sensing means each includes conductive transducing means coupled to said propagating means.
  • sensing means located beyond the delay line are bunched within a distance less than the length of the line, said path beyond the distance being substantially free of sensing means.
  • one of said sensing means is located at the beginning of the delay line opposite the other of said sensing means.
  • one of said sensing means is located at the beginning of the delay line opposite the others of said sensing means.
  • An electronic surveillance system comprising transmitter means for transmitting electromagnetic signals, label means attachable to an article under surveillance for receiving an interrogation from the transmitter and for retransmitting a reply, and receiver means for receiving and processing the reply; said label means including acoustic signal propagating means responsive to the interrogation from the transmitter for acoustically propagating signals corresponding to the interrogation along a path, a plurality of energy return means mounted on said propogating means at coded locations for removing a portion of the energy of each signal as it passes the location and making the removed portion of the signals available for retransmission to said receiver means at the reply, said energy return means including a first plurality of interconnected parallel transducers mounted on said propagating means and a second plurality of interconnected parallel transducers interleaved between said first plurality of transducers, said transducers being spaced so as to cor' respond with the wave length of the acoustic signals at the frequency of excitation of the signals.
  • An apparatus for responding to an electromagnetic interrogation and producing an electronic reply comprising signal propagating means responsive to the interrogation for propagating a signal corresponding to the interrogation along a path, a plurality of sensing means respectively mounted at coded locations along the path of said propagating means each for sensing the presence of a propagated signal at the location so that said sensing means together sense each propagated signal sequentially in a given coded time order, and energy carrier means coupled to each of said sensing means for forming the reply from the sequence of signals in the order that they are formed by said sensing means, said carrier means forming a signal line between said sensing means along which the signals can move substantially faster than the propagation rate of said propagation means.
  • said propagating medium comprises a piezoelectric material, said piezoelectric material being connected to said antenna means.
  • sensing means each includes conductive transducing means coupled to said propagating means.
  • said propagating medium comprises a piezoelectric material.
  • part of said propagating means forms a delay line free of sensing means, a plurality of said sensing means being located beyond the delay line.
  • sensing means located beyond the delay line are bunched within a distance less than the length of the line, said path beyond the distance being substantially free of sensing means.
  • said propagating means includes a piezoelectric crystal coupled to said antenna means so as to propagate the signals acoustically
  • said sensing means each including a first plurality of interconnected electrodes mounted on the surface of said crystal parallel to each other and transverse to the direction of propagation of the signals and a second plurality of interconnected electrodes parallel to each other and extending transverse to the direction of propagation of the signals and interleaved between said first plurality of said electrodes, said crystal being tuned to propagate signals at a predetermined expected received frequency, said electrodes being spaced from each other at one half the wavelength of the predetermined frequency, said carrier means being mounted on said crystal and connecting said sensing means.
  • each of said sensing means are removable from the locations for changing the coding of the reply.
  • An apparatus for responding to an electromagnetic interrogation and producing an electronic reply comprising acoustic signal propagating means responing means and a second plurality of interconnected parallel transducers interleaved between said first transducers.

Abstract

A passive label is interrogated by transmitting electromagnetic energy to the label and receiving electromagnetic energy from the label. Time delay means are provided in the label, preferably by utilization of surface acoustic waves, so that the returned energy is transmitted from the label after the interrogation energy has ceased. The label includes a substrate of piezoelectric material having coded information thereon, and serving to receive electromagnetic energy, convert it to acoustic energy, store the converted energy for a suitable time, reconvert the stored energy to electromagnetic energy and to transmit the electromagnetic energy to the receiver.

Description

United States Patent Cole et al.
[ 51 Dec. 12, 1972 (54] ELECTRONIC SURVEILLANCE SYSTEM [72] Inventors: Peter Harold Cole, 103 Strangways Terrace, N., Adelaide; Richard Vaughan, 6 Taylor St., Sydney, New South Wales, both of Australia 22 Filed: Feb. 26, 1970 21 Appl.No.: 14,607
[52] U.S. Cl ..343/6.5 SS, 343/68 R, 181/05 NP [51] Int. Cl ..G0ls 9/56 [58] Field of Search ..343/6.5 SS, 6.8 R
[56] References Cited UNITED STATES PATENTS 3,273,146 9/1966 Hurwitz ..343/6.5 SS X Primary Examiner-T. H. Tubbesing Attorney-McGlew and Toren ABSTRACT A passive label is interrogated by transmitting electromagnetic energy to the label and receiving electromagnetic energy from the label. Time delay means are provided in the label, preferably by utilization of surface acoustic waves, so that the returned energy is transmitted from the label after the interrogation energy has ceased. The label includes a substrate of piezoelectric material having coded information thereon, and serving to receive electromagnetic energy, convert it to acoustic energy, store the converted energy for a suitable time, reconvert the stored energy to electromagnetic energy and to transmit the electromagnetic energy to the receiver.
27 Claims, 25 Drawing Figures PM'EIITED I2 I97? 3. 706. 094
sum 01 or 1 1 TRANSMITTER RECEIVER ENCODER IFIG.| 5 z OSCILLATOR -D- AMPLIFIER FILTER V OSCILLATOR /8 II REF. OUTPUT Ill 2% 2 M U -lo- 3 I 20- J c A Frequency 080 900 920 94 l MHZ -40r- INVENTORS PETER HAROLD cou-z mcuAno VAUGHAN by m,
ATTORNEYS PATENTEDBEE 12 m2 3.706.094
sum OEUF 11 E g g g; 2' 1 S E 2 A 8 2 x g 8 m INVENTORS PETER HAROLD COLE RICHARD VAUGHAN ATTORNIYH FIG.
P'ATE'NTEDnEc 12 I972 SHEET an 0F 11 CONNECTION Tp ANTENNA w E F R G 0 MY E m AA m E mm mun P U E M SWR ADSORBER TO ANTENNA FIG."
INVENTORS PETER HAROLD -co| E RICHARD vgusnm by .Q.
hjvzfiwq,
COAXIAL OUT ATTORN EYS 3.706094 sum 05 0F 11 PMENTED can 12 me H H= W o So 0 TKEW 3 9.
INVENTORS PETER HAROLD COLE RlCHARD VAUGHAN ATTORNEYS PATENTEDUEB I2 m2 SHEET GATE DEUF 11 3! I! e o E m J n. E 0
INVENTORS PETER HAROLD COLE RICHARD VAUGHAN y ATTORNEYS PA'TENTEBBEB 12 2 3.706.094
SHEET U7UF 11 l +2ov FIG.I6 i I I LOW POWER 7 T AMPLIFIER g 1 INPUT w1+--{ OUTPUT DI 56 SETTING CIRCUIT INPUT OUTPUT F|G |7 O 0 MEDIUM POWER AMPLIFIER 5 8 FIGJB OUTPUT INPUT P I I l -2ov INVENTORS PETER HAROLD COLE RICHARD VAUGHAN ATTORNEYS P'A'TENTED DEC 12 I972 SHEET 08 0F 11 ONGE PETER HAROLD COLE RICHARD VAUGHAN ATTORNEYS PATENTEU 12 I97? 3. 706, 094
wmszs-o L mm mm E;
INVENTORS PETER HAROLD COLE RICZHARD VAUGHAN ATTORNEYS FIG.2|
PATENTEU 12 \973 3. 706, 094
sum 10 0F 11 GATED RF N T JV fi INVENTORS if 0(5 PETER HAROLD COLE R'CHARD VAUGHAN ATTORNEYS ELECTRONIC SURVEILLANCE SYSTEM BACKGROUND OF THE INVENTION 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.
SUMMARY OF THE INVENTION The present invention utilizes a method which achieves the desired result, incorporating time delay in the label preferably by utilization of surface acoustic waves so that the reply energy is transmitted after the interrogation energy has died away.
The facilities offered by the present invention provide for the open or secret interrogation by radio waves of coded information from prepared passive labels by a remote sensing apparatus. Some of the many applications are: a. Automatic sorting of passengers luggage in airline terminals. b. Sorting and routing of letters and parcels in postal services. c. Identification, accreditation and location of personnel in security installations, factories, hospitals or military theatres. d. Ticketing of passengers in transportation systems. e. 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 unauthorized passage of such tagged items through each exit will be detected.
A system according to the invention may be set up to provide the following features:
a. The system returns several, or even many, binary digits (bits) of information to the interrogator. A social security number for example requires 30 bits of information.
b. The labels containing the coded information 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.
c. 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.
d. The coded signal is distinguishable from background clutter signals accidently produced by the environment of the label being interrogated.
This distinction from clutter signals is made by the incorporated time delay and, where necessary, by pulsetime coding of the reply signal.
e. The encoding of the information on the label can be performed by simple means at the time the label is put into service. Users of the system need stock only blank labels rather than a complete set of labels with all possible codes.
To better illustrate the principles involved, there is described below one possible design or embodiment for a particular system, namely a system for the encoding of 10 bits of information in a plastic card 5 cm g 8 cm X 1 mm, the card to be sensed from a distance of 3 meters. The card may have any orientation and can be moving at a speed of up to 1 meter per sec. in any direction, as may be required for example in a baggage sorting operation.
The general principle of a system according to this fon'n of the invention is to provide in the label card a means of receiving electromagnetic energy, converting it to acoustic form, storing it for a suitable time, reconverting it to electromagnetic energy for retransmission in a coded form which then contains the information encoded in the label.
A further form of the invention is also described in which a carrier frequency of 10 MHz is used.
BRIEF DESCRIPTION OF THE DRAWINGS:
In order to assist in an understanding of the system it is described with reference to the accompanying drawings in which:
FIG. 1 is a block diagram of the system as a whole,
FIG. 2 is a similar diagram of the transmitter unit,
FIG. 3 is a curve showing the passband of the output filter,
FIG. 4 is an isometric view of a label for use with the system,
FIG. 5 is a view of a portion of the label to an enlarged scale,
FIG. 6 shows details of one of the array elements of the label,
FIG. '7 is a diagram showing the sequence of pulses arriving at the receiver,
FIG. 8 is a block diagram of the receiver,
FIG. 9 is a block diagram of the signal processor, and
FIGS. 10 and 11 show modified forms of array structures for labels intended for simplified applications,
FIG. 12 is a block diagram of the system as a whole,
FIG. 13 is a diagram of the antennas used in the transmitter and receiver units,
FIG. 14 is a circuit diagram of the master oscillator for the transmitter unit (and also of the local oscillator for the receiver unit),
FIG. 15 is a circuit diagram of a gated amplifier used in the transmitter unit (and also of a gated amplifier used in the receiver unit),
FIG. 16 is a circuit diagram of one of two low power amplifiers used in the transmitter unit,
FIG. 17 is a circuit diagram of a dynamic range expanding and power level setting unit used in the transmitter,
FIG. 18 is a circuit diagram of a medium power amplifier used in the transmitter unit,
FIG. 19 is a circuit diagram of the transmitter output amplifier,
FIG. 20 is a diagram of the coded label,
FIG. 21 is a diagram of the surface acoustic delay line,
FIG. 22 is a circuit diagram of the receiver preamplifier,
FIG. 23 is a circuit diagram of a gated rf amplifier used in the receiver,
FIG. 24 is a circuit diagram of a balanced mixer and balance to unbalance amplifier used in the receiver,
FIG. 25 is a circuit diagram of a narrow band amplifier in the output of the receiver.
The basic components of the system are shown in block diagram in FIG. 1. The system contains a transmitter of electromagnetic waves 1, an information carrying label 2, a receiver of electromagnetic waves 3, all of which are operated simultaneously. There is also a customer encoding device 4, which is used to encode the desired information on to previously blank stock labels prior to their use in the system.
Further details of the transmitter unit appear in FIG. 2. The transmitter employs standard UHF and microwave technology. The principle components and specifications are:
a. A master oscillator 5 operating at (in this example) 897.5 MHZ, with a main output 6 and reference output 7 as shown.
b. A low frequency pulse oscillator 8 producing rectangular pulses of duration 100 nanoseconds, rise time 5 nanoseconds, pulse repetition frequency KHZ, provided with a main output 9 and a reference output 10, as shown.
c. A pulsed power amplifier 11, with center frequency 915 MHZ, band width 50 MHZ, peak output power 100 watts, pulse length 100 nanoseconds, pulse repetition frequency 10 KHZ, and on/off ratio in excess of 150 decibels.
d. An output filter 12, with a passband shown in FIG. 3, to restrict the frequency components of the output radiation to those allowed by the statutory authority. The position of the carrier in relation to the passband of FIG. 3 has been chosen to provide vestigial sideband modulation.
e. A microwave antenna system 13, which illuminates the area containing the information label to be read. An antenna gain of 6 decibels is chosen in this design. Higher figures can be used to advantage and without difficulty.
f. Under some circumstances it is useful to employ microwave adsorbing materials 14, in the main lobe of the transmitter antenna to avoid electromagnetic echo signals from distant objects.
The construction of a suitable information carrying passive label is shown in the isometric drawing FIG. 4. The outer section is in the form of a plastic or cardboard card 15, which serves as a protection for the inner sensitive elements 16. Printed or punched information 17 can be included on the card if this is convenient for other purposes. The part of the card which interacts with the sensing system is a microwave antenna system 18, one form of which might be a lumped loaded loop for omni directional response as shown. This antenna is connected via a transmission line 19, to the part of the card on which the information is encoded. This latter element is shown in more detail in FIG. 5.
The coding portion of the card consists first of a piezoelectric substrate 20, in this example a plate of single crystal quartz is used. Other materials can be used providing that they singly or in combination provided a high piezoelectrics co-efficient transducer region and a low acoustic loss propogation region.
The information is encoded on the substrate in the form of the spatial pattern formed by the conducting electrode array deposited on the substrate surface. Details of the space pattern appropriate to the ten bit binary code 1 10100111 1 are shown in FIG. 5, and the details of one of the array elements are shown in FIG. 6. The array contains an end element 22, consisting of 26 electrodes and a set of coding elements 23, consisting of 16 electrodes. Alternate electrodes are connected to different conductors of the transmission line 19, from the microwave antenna 18. The spacing of the electrodes in this example is approximately 2pm, the precise distance is adjusted to be one-half of a wave length of a surface electroacoustic wave at the operating center frequency of 9 15 MHZ.
The precise manner in which the desired code is carried by the array is that the connection or disconnection of an array element 23, at a given point on the main transmission line 19, signifies respectively a one or a zero binary digit. In practice all cards are manufactured with a full sequency of ones by having all array elements present. The required code is impressed on the card by the user by severing the connections of an appropriate number of array elements from the main transmission line. Labels may, however, be coded during manufacture by omitting the electrode structure from one or more elements or by not connecting them to the transmission line.
In operation, the card receives the pulsed electromagnetic energy via its antenna 18, and energizes the entire array along the transmission line 19. The various elements of the array launch surface electroacoustic waves along the piezoelectric substrate in the direction of the transmission line. After a time equal to the propogation time for such waves along the blank portion 24, of the transmission line, the electroacoustic waves are reconverted to electromagnetic energy and reradiate electromagnetic waves via the antenna 18. This reradiated energy is picked up and processed by the receiver 3.
A diagram of the sequence of pulses which arrive at the receiver is shown in FIG. 7. The sequence consists of a large amplitude pulse 25, arriving directly from the transmitter a series of unwanted interference pulses 26, resulting from propogation of electroacoustic pulses between various elements of the coding array, followed by the wanted set of pulses 27, which result from propogation of electroacoustic pulses between the end element 22, and the set of coding elements 23. It is this last group of pulses which are free of interference and contain the coded information, which are processed by the receiver in the manner described below:
The various components of the receiver 3, are shown in block diagram form in FIG. 8. The directional antenna 28 is similar in design to the transmitter antenna 13. A band pass filter 29 serves to reject possible radio frequency interference from sources unrelated to this system. A limiting device 30 protects the receiver from saturation or overload from the large amplitude transmitted pulse. A low noise (noise figure less than 6 db) pre-amplifier 31, and post-amplifier fitted with automatic gain control 32, provide an amplified received pulse sequence to the signal processing unit 33. Details of the design of the signal processing unit capable of providing for maximum sensitivity, using the technique of synchronous detection, are given below.
A block diagram of the signal processor appears in F IG. 9. The amplified pulse sequence from the receiver enters at 34, is divided into two signals, fed via buffer amplifiers 35, to the synchronous detectors 36 and 37. The reference drive for detector 36 is obtained from the transmitter master oscillator signal which enters at 7. The reference drive for detector 37, is derived from the same reference via the "/2 phase shift network 38. As a result the detectors 36 and 37 perform respectively in phase and quadrature phase detection of the received signal with respect to the transmitter master oscillator. The detected signals are fed to buffer amplifiers 39, from each of which outputs, in the present example, are available. Each of the 10 outputs from these buffer amplifiers is then fed to one of 20 gating circuits 40, only two of which are shown. These gates are controlled by a count down circuit 41, which is synchronized with the transmitted pulse via a signal brought from the transmitter through the reference line 10. The count down circuit has ten output pulses each with a width equal to the transmitter pulse, 100 nsec in this example. The various output pulses have different time delays from the transmitted pulse, each adjusted to the delay expected from one or another of the pulses in the received pulse train 27. The outputs of the various gates 40 are filtered in low pass filters 42 which set the effective noise band width of the system. The outputs of these filters are fed through bufi'er amplifiers (not shown) to the square law devices 43, which produce a (unidirectional) output proportional to the square of the input signal over the designed operating range. The design of such a unit presents only a simple problem requiring for solution an operational amplifier and a semiconductor diode network. As a final step in the signal processor the outputs of corresponding pairs of square law devices 43, are added and fed to the set of ten output terminals 44, (only one shown) which provide the 10 bits of information. A reference signal from each of these bits is returned to the receiver via line 45, to provide automatic gain control. The presence of an automatic gain control signal requires at least one non zero bit in the coded sequence. Inclusion of odd parity check in the code ensures the presence of this required bit. The inclusion of this check bit provides an additional safeguard against false triggering of the system by spurious objects.
The outputs of the above described signal processor can be fed to a wide range of logic circuits, not shown in FIG. 9, to perform the various command identification and sorting tasks required of the overall system. The design of such logic circuits follows well established procedures.
Calculations show that the power losses occurring in various parts of the overall transmission path from transmitter to receiver are:
a. Electromagnetic propogation loss from transmitter antenna to label antenna: 33 db.
b. Electromagnetic to electroacoustic conversion loss: 38 db.
0. Electroacoustic propogation loss: 2db.
d. Electroacoustic to electromagnetic conversion loss: 31 db.
e. Electromagnetic propogation loss from label antenna to receiver antenna: 33 db.
The overall transmission path loss is 137 db.
The noise band width of the receiver is determined by the low pass filter 42, which follows the synchronous demodulation and is set to l KHZ. The input noise level of the receiver, allowing for 6 db. noise figure and 1 db loss in the band pass filter 29, is --l 67 db W. The input signal level at the receiver is l07 db W. The signal to noise ratio at the receiver is thus db and the system is not receiver noise limited.
The system depends for its success on distinguishing the acoustically delayed echos from background clutter produced by direct electromagnetic echo. Since the acoustic time delay before retransmission of the coded pulse sequence is, in this example, in excess of 3 microseconds, the relevant electromagnetic echos will be via propogation paths of lengths in excess of 900 meters, and will in most circumstances be suitably small. Problems which may arise can be eliminated by proper use of the antenna patterns of the transmitter and receiver, in conjunction with suitably placed natural or artificial microwave adsorbers. Calculations have shown that direct echo can be reduced well below the acoustic echo level if the resultant enclosure has a Q factor of less than 100, and the system is then not limited by background clutter.
There are certain obvious variations from the design example described in detail which may be made to suit particular applications. In particular some of them are:
a. Change of carrier frequency from 897.5 MHZ. The dimensions of the electroacoustic conversion array may be changed to lower or higher values as required by the technology to be employed in their manufacture.
b. Pulse length and pulse repetition rate may be varied to make a longer or more compact code possible.
c. Changes may be made in transmitter power level and the characteristics of transmitter, receiver and label antennas, including use of duplexing, to provide various microwave propogation systems.
d. A range of substrate materials can be used for the acoustic propogation, including piezoelectric materials whose acoustic loss is not necessarily low, deposited on low acoustic loss substrates. Magnetostriction devices may also used in place of or in conjunction with the piezoelectric materials to accomplish the electroacoustic conversion.
e. The transducer array structure can be modified in number and shape of elements, and in the manner of its interconnection to the transmission line.
f. Coding methods other than the simple binary, such as pulse height, width or position, can be used.
g. The disposition of the various elements in the card, and the size shape and nature of the card can be varied to suit particular applications. In particular it may be advantageous to employ the edge rather than the surface of the acoustic substrate for the propogation of the acoustic waves.
h. The code and array structure can be simplified to fewer, or even one, element for simplified applications such as object surveillance as described in application (e) of section 1. Use is made of a surface wave reflector, or a rat race propogation path, in this case. Two such possible simplified structures are shown diagrammatically in FIG. 10 and FIG. 11. In the structure of FIG. 10, use is made of a surface wave reflector 46, which returns the acoustic pulse to the single acousticwave launching and receiving array 47. In the structure of FIG. 11, the surface wave is constrained by suitable groves 48, etched in the surface of the quartz substrate to propogate around a circular, or rat-race", propogation path so as to again return to the single acousticwave launching and receiving array after a suitable time delay.
i. As an alternative to using a pulse code in simple surveillance applications it is in fact sufficient to couple a resonant acoustic structure of sufficiently high such that it will continue to ring after the termination of the transmitter pulse. If the ringing time be long enough the resulting echo is easily distinguished from background clutter caused by direct electromagnetic echo.
To provide further assistance in understanding the system there is described below with reference to FIGS. 12 to 21, a version which operates at a carrier frequency of MHz and provides for a return signal carrying five bits of information.
The basic components of this realization of the system are shown in FIG. 12. The system is controlled by a pulse repetition frequency generator 50, (of which no schematic is given because it is a commercial instrument), which sends pulses at a 50 KPPS rate to the pulse width generator 51 (another commercial instrument); the output pulses being 0.5 ,1. sec. long. The gated amplifier 52, shown in FIG. 15 is controlled by the pulse width generator, and feeds 0.5 p. sec. pulses of radio frequency energy which have been generated by master oscillator 53, shown in FIG. 14, to the series of low power amplifiers 54 and 55 shown in FIG. 16. The amplified gated radio-frequency pulses are expanded in dynamic range by range expander and level setting circuits 56, shown in FIG. 17, and, after further amplification in medium power amplifier 57 shown in FIG. 18 and output amplifier 58, shown in FIG. 19 are fed to the transmitter antenna 59. The transmitter antenna is in the form of a shielded square magnetic dipole of scale 12 inches of a form of construction well known for aircraft direction finder loops and is loaded to a Q factor of 5. Details of the transmitter antenna are shown in FIG. 13, and schematic diagrams of many of the transmitter circuits are provided in FIGS. 14 to 19 inclusive.
The signal from the transmitter antenna travels by nearfield electromagnetic propogation to the coded label 60, the detailed construction of which is shown in FIGS. 20 and 21. The figures show a label suitable for a reply signal returning the particular five-bit code lllll. FIG. 20 shows the label used, consisting of a printed-circuit magnetic loop antenna 71 on a 6 inches X 4 inches epoxy-glass card 72 tuned to resonate at 10 Mc/s by a fixed capacitor 73 and loaded by a fixed resistor 74 to a Q factor of 5. The coding portion of the label is again a quartz substrate 5 cm X 2.5 cm X 2 cm thickness, carrying the conducting electrode pattern 75 shown in FIG. 21, which returns the five bit binary code 11111, connected to the antenna 71 as shown in FIG. 20.
The electrode pattern 75 is constructed and operates in a manner similar to that described in connection with the first embodiment of the invention. It will be noted however that the dimensions are quite different due to the use of a lower carrier frequency. In the electrode pattern 75 the spacing between individual electrodes of the pattern is 0.1625 mm. After a delay of approximately 6 p. sec. following the completion of the transmitter pulse, the coded reply signal is retransmitted by the label and a portion of the reply energy is received by the receiver antenna 61. The output signal for the receiver antenna is initially amplified by lownoise receiver amplifier 62, shown in FIG. 22, which has been specially designed to provide rapid recovery from overload, and is then passed to gated amplifier 63, shown in FIG. 23.
The gated amplifier 63 is one of two gated amplifiers 63 and 64 which are controlled in the receiver from the pulse repetition frequency generator 50 via delay generator 65 and pulse width generator 66. The function of delay generator 65 and pulse width generator 66 is to open the receiver gate at a period of time so delayed with respect to the time of the transmitter pulse as to correspond to the detection of a particular bit in the reply code. Varying the amount of delay provided by delay generator 65 allows various bits in the reply coded to be detected separately.
The further operation of the receiver is concerned with the balanced mixer 67, shown in FIG. 24, which receives the gated signals both from the low noise amplifier 62 and a highly stable local oscillator 68 and produces at its output the difference frequency resulting from the mixing of the two signals. This frequency is equal to the difference in frequency between master oscillator 53 and local oscillator 68. It is important to the operation of the overall system that master oscillator 53 and local oscillator 68 should have a closely controlled frequency to maintain the difference frequency within the passband of the narrow band tuned amplifier 68a, shown in FIG. 25. This difference frequency must be suitably chosen and must lie sufficiently about zero frequency (that is DC) to avoid l /f or flicker noise, but below the pulse repetition frequency generated by pulse repetition frequency generator 50, such that no mixing products of the gate transients of gates 63 and 64 will contaminate or add noise to the system output. The output from tuned amplifier 68a is fed to a nonlinear detector 69 which measures the magnitude of the difference frequency signal from tuned amplifier 68a and registers a l as being received from label 60 for the particular bit position then under examination if this signal suitably exceeds the system noise level.
We claim:
1. An electronic surveillance system, comprising transmitter means for transmitting electromagnetic signals, label means adapted for attachment to an article under surveillance for receiving a signal from said transmitter means and for retransmitting a reply, and receiver means for receiving and processing the reply; said label means including signal propagating means responsive to the signal from the transmitter for propagating the transmitted signal along a path at a rate slower than electromagnetic propogation, a plurality of sensing means mounted at coded locations along the path of said propagating means each for sensing the presence of a propagated signal at the location so that said sensing means together sense each signal sequentially in a given coded time order, an energy carrier means coupled to each of said sensing means for retransmitting the sequence of signals in the order they are sensed by said sensing means as the reply, said carrier means forming a signal path between said sensing means so that signals can move faster than the propagation rate of said propagating means.
2. A system as in claim 1, wherein said carrier means includes a conductive medium.
3. A system as in claim 1, wherein said sensing means each includes conductive transducing means coupled to said propagating means.
4. An apparatus as in claim 3, wherein said carrier means includes a conductive medium.
5. An apparatus as in claim 1, wherein said propagating medium comprises a piezoelectric material.
6. A system as in claim 1, wherein said propagating means forms a delay line on part of the path free of sensing means, a plurality of said sensing means being located beyond the delay line along the path.
7. A system as in claim 6, wherein said sensing means located beyond the delay line are bunched within a distance less than the length of the line, said path beyond the distance being substantially free of sensing means.
8. A system as in claim 7 wherein one of said sensing means is located at the beginning of the delay line opposite the other of said sensing means.
9. A system as in claim 6, wherein one of said sensing means is located at the beginning of the delay line opposite the others of said sensing means.
10. An electronic surveillance system comprising transmitter means for transmitting electromagnetic signals, label means attachable to an article under surveillance for receiving an interrogation from the transmitter and for retransmitting a reply, and receiver means for receiving and processing the reply; said label means including acoustic signal propagating means responsive to the interrogation from the transmitter for acoustically propagating signals corresponding to the interrogation along a path, a plurality of energy return means mounted on said propogating means at coded locations for removing a portion of the energy of each signal as it passes the location and making the removed portion of the signals available for retransmission to said receiver means at the reply, said energy return means including a first plurality of interconnected parallel transducers mounted on said propagating means and a second plurality of interconnected parallel transducers interleaved between said first plurality of transducers, said transducers being spaced so as to cor' respond with the wave length of the acoustic signals at the frequency of excitation of the signals.
11. A system as in claim 10, wherein said propagating means includes a piezoelectric crystal.
12. A system as in claim 11, wherein said energy return means are mounted on the surface of the crystal and the energy is propagated along that surface of the crystal.
13. An apparatus for responding to an electromagnetic interrogation and producing an electronic reply, comprising signal propagating means responsive to the interrogation for propagating a signal corresponding to the interrogation along a path, a plurality of sensing means respectively mounted at coded locations along the path of said propagating means each for sensing the presence of a propagated signal at the location so that said sensing means together sense each propagated signal sequentially in a given coded time order, and energy carrier means coupled to each of said sensing means for forming the reply from the sequence of signals in the order that they are formed by said sensing means, said carrier means forming a signal line between said sensing means along which the signals can move substantially faster than the propagation rate of said propagation means.
14. An apparatus as in claim 13, wherein said carrier means includes a conductive medium.
15. An apparatus as in claim 13, further comprising antenna means for responding to the interrogation and applying it to said propagating means, said antenna means being connected to said carrier means for retransmitting the sequence of signals formed as the reply.
16. An apparatus as in claim 15, wherein said propagating medium comprises a piezoelectric material, said piezoelectric material being connected to said antenna means.
17. An apparatus as in claim 13, wherein said sensing means each includes conductive transducing means coupled to said propagating means.
18. An apparatus as in claim 13, wherein said propagating medium comprises a piezoelectric material.
19. An apparatus as in claim 13, wherein part of said propagating means forms a delay line free of sensing means, a plurality of said sensing means being located beyond the delay line.
20. An apparatus as in claim 19, wherein said sensing means located beyond the delay line are bunched within a distance less than the length of the line, said path beyond the distance being substantially free of sensing means.
21. An apparatus as in claim 20, wherein one of said sensing means is located at the beginning of the delay line opposite the other of said sensing means.
22. An apparatus as in claim 19, wherein one of said sensing means is located at the beginning of the delay line opposite the others of said sensing means.
23. An apparatus as in claim 13, further comprising antenna means responsive to the interrogation and coupled to said propogating means, said antenna means being connected to said sensing means for transmitting the reply electromagnetically.
24. An apparatus as in claim 23, wherein said propagating means includes a piezoelectric crystal coupled to said antenna means so as to propagate the signals acoustically, said sensing means each including a first plurality of interconnected electrodes mounted on the surface of said crystal parallel to each other and transverse to the direction of propagation of the signals and a second plurality of interconnected electrodes parallel to each other and extending transverse to the direction of propagation of the signals and interleaved between said first plurality of said electrodes, said crystal being tuned to propagate signals at a predetermined expected received frequency, said electrodes being spaced from each other at one half the wavelength of the predetermined frequency, said carrier means being mounted on said crystal and connecting said sensing means.
25. An apparatus as in claim 13, wherein each of said sensing means are removable from the locations for changing the coding of the reply.
26. An apparatus for responding to an electromagnetic interrogation and producing an electronic reply, comprising acoustic signal propagating means responing means and a second plurality of interconnected parallel transducers interleaved between said first transducers.
27. An apparatus as in claim 26, wherein said propagating means is adapted to respond to signals of a given frequency, said transducers being spaced from each other one half wavelength of the frequency.
l I I l i UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,706,09 D t d December 12, 1972 lnventm-(s) Peter Harold Cole and Richard Vaughan It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:
In the heading of the patent, add
the following:
[30] Foreign Application Priority Data February 26, 1969 Australia. .5l0 l8/69- Signed and sealed this 1st day of May 1973.
(SAAL) Attest:
EDWARD M. FLETCHER, JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents FORM P0-1050 (10-69) a us covznumzur ranmus ornc: nu o-ase-au,

Claims (27)

1. An electronic surveillance system, comprising transmitter means for transmitting electromagnetic signals, label means adapted for attachment to an article under surveillance for receiving a signal from said transmitter means and for retransmitting a reply, and receiver means for receiving and processing the reply; said label means including signal propagating means responsive to the signal from the transmitter for propagating the transmitted signal along a path at a rate slower than electromagnetic propogation, a plurality of sensing means mounted at coded locations along the path of said propagating means each for sensing the presence of a propagated signal at the location so that said sensing means together sense each signal sequentially in a given coded time order, an energy carrier means coupled to each of said sensing means for retransmitting the sequence of signals in the order they are sensed by said sensing means as the reply, said carrier means forming a signal path between said sensing means so that signals can move faster than the propagation rate of said propagating means.
2. A system as in claim 1, wherein said carrier means includes a conductive medium.
3. A system as in claim 1, wherein said sensing means each includes conductive transDucing means coupled to said propagating means.
4. An apparatus as in claim 3, wherein said carrier means includes a conductive medium.
5. An apparatus as in claim 1, wherein said propagating medium comprises a piezoelectric material.
6. A system as in claim 1, wherein said propagating means forms a delay line on part of the path free of sensing means, a plurality of said sensing means being located beyond the delay line along the path.
7. A system as in claim 6, wherein said sensing means located beyond the delay line are bunched within a distance less than the length of the line, said path beyond the distance being substantially free of sensing means.
8. A system as in claim 7, wherein one of said sensing means is located at the beginning of the delay line opposite the other of said sensing means.
9. A system as in claim 6, wherein one of said sensing means is located at the beginning of the delay line opposite the others of said sensing means.
10. An electronic surveillance system comprising transmitter means for transmitting electromagnetic signals, label means attachable to an article under surveillance for receiving an interrogation from the transmitter and for retransmitting a reply, and receiver means for receiving and processing the reply; said label means including acoustic signal propagating means responsive to the interrogation from the transmitter for acoustically propagating signals corresponding to the interrogation along a path, a plurality of energy return means mounted on said propogating means at coded locations for removing a portion of the energy of each signal as it passes the location and making the removed portion of the signals available for retransmission to said receiver means at the reply, said energy return means including a first plurality of interconnected parallel transducers mounted on said propagating means and a second plurality of interconnected parallel transducers interleaved between said first plurality of transducers, said transducers being spaced so as to correspond with the wave length of the acoustic signals at the frequency of excitation of the signals.
11. A system as in claim 10, wherein said propagating means includes a piezoelectric crystal.
12. A system as in claim 11, wherein said energy return means are mounted on the surface of the crystal and the energy is propagated along that surface of the crystal.
13. An apparatus for responding to an electromagnetic interrogation and producing an electronic reply, comprising signal propagating means responsive to the interrogation for propagating a signal corresponding to the interrogation along a path, a plurality of sensing means respectively mounted at coded locations along the path of said propagating means each for sensing the presence of a propagated signal at the location so that said sensing means together sense each propagated signal sequentially in a given coded time order, and energy carrier means coupled to each of said sensing means for forming the reply from the sequence of signals in the order that they are formed by said sensing means, said carrier means forming a signal line between said sensing means along which the signals can move substantially faster than the propagation rate of said propagation means.
14. An apparatus as in claim 13, wherein said carrier means includes a conductive medium.
15. An apparatus as in claim 13, further comprising antenna means for responding to the interrogation and applying it to said propagating means, said antenna means being connected to said carrier means for retransmitting the sequence of signals formed as the reply.
16. An apparatus as in claim 15, wherein said propagating medium comprises a piezoelectric material, said piezoelectric material being connected to said antenna means.
17. An apparatus as in claim 13, wherein said sensing means each includes conductive transducing means coupled to said propagating means.
18. An apparatus as in claim 13, wherein said propagating medium compRises a piezoelectric material.
19. An apparatus as in claim 13, wherein part of said propagating means forms a delay line free of sensing means, a plurality of said sensing means being located beyond the delay line.
20. An apparatus as in claim 19, wherein said sensing means located beyond the delay line are bunched within a distance less than the length of the line, said path beyond the distance being substantially free of sensing means.
21. An apparatus as in claim 20, wherein one of said sensing means is located at the beginning of the delay line opposite the other of said sensing means.
22. An apparatus as in claim 19, wherein one of said sensing means is located at the beginning of the delay line opposite the others of said sensing means.
23. An apparatus as in claim 13, further comprising antenna means responsive to the interrogation and coupled to said propogating means, said antenna means being connected to said sensing means for transmitting the reply electromagnetically.
24. An apparatus as in claim 23, wherein said propagating means includes a piezoelectric crystal coupled to said antenna means so as to propagate the signals acoustically, said sensing means each including a first plurality of interconnected electrodes mounted on the surface of said crystal parallel to each other and transverse to the direction of propagation of the signals and a second plurality of interconnected electrodes parallel to each other and extending transverse to the direction of propagation of the signals and interleaved between said first plurality of said electrodes, said crystal being tuned to propagate signals at a predetermined expected received frequency, said electrodes being spaced from each other at one half the wavelength of the predetermined frequency, said carrier means being mounted on said crystal and connecting said sensing means.
25. An apparatus as in claim 13, wherein each of said sensing means are removable from the locations for changing the coding of the reply.
26. An apparatus for responding to an electromagnetic interrogation and producing an electronic reply, comprising acoustic signal propagating means responsive to the interrogation for propagating signals corresponding to the interrogation acoustically along a path, a plurality of energy return means mounted on said propagating means at coded locations for removing a portion of the energy from each signal as it passes the location and for making the removed portion of the signals available for retransmission as the reply, said energy return means including a plurality of interconnected parallel transducers mounted on said propagating means and a second plurality of interconnected parallel transducers interleaved between said first transducers.
27. An apparatus as in claim 26, wherein said propagating means is adapted to respond to signals of a given frequency, said transducers being spaced from each other one half wavelength of the frequency.
US14607A 1970-02-26 1970-02-26 Electronic surveillance system Expired - Lifetime US3706094A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US1460770A 1970-02-26 1970-02-26

Publications (1)

Publication Number Publication Date
US3706094A true US3706094A (en) 1972-12-12

Family

ID=21766489

Family Applications (1)

Application Number Title Priority Date Filing Date
US14607A Expired - Lifetime US3706094A (en) 1970-02-26 1970-02-26 Electronic surveillance system

Country Status (1)

Country Link
US (1) US3706094A (en)

Cited By (81)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3750167A (en) * 1971-07-22 1973-07-31 Gen Dynamics Corp Postal tracking system
US3774205A (en) * 1971-08-02 1973-11-20 Ncr Co Merchandise mark sensing system
US3886548A (en) * 1973-10-12 1975-05-27 Boeing Co Responder for use in a passive identification system
US3981011A (en) * 1975-03-31 1976-09-14 Sperry Rand Corporation Object identification system using an RF roll-call technique
US4019181A (en) * 1974-07-19 1977-04-19 U.S. Philips Corporation Transponder system
US4027840A (en) * 1974-10-15 1977-06-07 International Standard Electric Corporation Vehicle position indicator with radar interrogation each of spaced transponders disposed along a pathway for the vehicle
US4059831A (en) * 1975-10-06 1977-11-22 Northwestern University Passive transponders using acoustic surface wave devices
US4096477A (en) * 1975-10-06 1978-06-20 Northwestern University Identification system using coded passive transponders
EP0002595A1 (en) * 1977-12-09 1979-06-27 Lintech Instruments Limited Transponders
EP0005534A1 (en) * 1978-05-16 1979-11-28 Siemens Aktiengesellschaft Device for identifying objects and persons
DE3102334A1 (en) * 1980-01-25 1981-12-10 Unisearch Ltd., Kensington, New South Wales TEMPERATURE REMOTE MEASURING DEVICE
GB2165411A (en) * 1984-10-09 1986-04-09 X Cyte Inc Surface acoustic wave passive transponder having amplitude and phase-modifying surface pads
DE3438052A1 (en) * 1984-10-09 1986-04-24 X-Cyte, Inc., Mountain View, Calif. SYSTEM FOR INQUIRING A PASSIVE, PHASE-CODED INFORMATION WITH TRANSPONDER
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
US4625208A (en) * 1983-06-30 1986-11-25 X-Cyte Inc. Surface acoustic wave passive transponder having acoustic wave reflectors
US4625207A (en) * 1983-06-30 1986-11-25 X-Cyte Inc. Surface acoustic wave passive transponder having amplitude and phase-modifying surface pads
US4658252A (en) * 1984-08-13 1987-04-14 Gte Government Systems Corporation Encoder/decoder for card entry system
US4698631A (en) * 1986-12-17 1987-10-06 Hughes Tool Company Surface acoustic wave pipe identification system
EP0240761A1 (en) * 1983-07-01 1987-10-14 M & FC HOLDING COMPANY, INC. Meter data gathering and transmission system
AU568157B2 (en) * 1984-10-09 1987-12-17 X-Cyte Inc. Compensating for non-linear frequency variation in a system for interrogating a transponder
US4725841A (en) * 1983-06-30 1988-02-16 X-Cyte, Inc. System for interrogating a passive transponder carrying phase-encoded information
JPS6363875A (en) * 1986-09-04 1988-03-22 株式会社ゼネラルリサ−チオブエレクトロニツクス Key device
US4734698A (en) * 1985-10-31 1988-03-29 X-Cyte, Inc. Passive interrogator label system having offset compensation and temperature compensation for a surface acoustic wave transponder
US4746830A (en) * 1986-03-14 1988-05-24 Holland William R Electronic surveillance and identification
US4807140A (en) * 1983-11-10 1989-02-21 Saulnier Dominique C Electronic label information exchange system
WO1990004794A1 (en) * 1988-10-27 1990-05-03 Micro Design A.S. Method for processing transmitted and reflected signals for removing unwanted signals and noise from wanted signals
US4931664A (en) * 1988-08-02 1990-06-05 Gte Products Corporation Controller for coded surface acoustical wave (SAW) security system
US4945354A (en) * 1988-11-25 1990-07-31 Gte Products Spurious signal correction for surface acoustic wave (SAW) security devices
US4980680A (en) * 1988-08-02 1990-12-25 Gte Products Corp. And Gte Laboratories, Inc. Coded surface acoustical wave (saw) motor vehicle security device
EP0413634A2 (en) * 1989-08-17 1991-02-20 Mitsubishi Jukogyo Kabushiki Kaisha ID card
US5115160A (en) * 1989-08-28 1992-05-19 Gte Products Easily encodable surface acoustic wave (SAW) security devices
WO1994023981A1 (en) * 1993-04-08 1994-10-27 Siemens Aktiengesellschaft Obstacle-detection device
US5423334A (en) * 1993-02-01 1995-06-13 C. R. Bard, Inc. Implantable medical device characterization system
US5448110A (en) * 1992-06-17 1995-09-05 Micron Communications, Inc. Enclosed transceiver
US5469170A (en) * 1994-10-20 1995-11-21 The United States Of America As Represented By The Secretary Of The Army Passive SAW-ID tags using a chirp transducer
US5497140A (en) * 1992-08-12 1996-03-05 Micron Technology, Inc. Electrically powered postage stamp or mailing or shipping label operative with radio frequency (RF) communication
US5776278A (en) * 1992-06-17 1998-07-07 Micron Communications, Inc. Method of manufacturing an enclosed transceiver
US5779839A (en) * 1992-06-17 1998-07-14 Micron Communications, Inc. Method of manufacturing an enclosed transceiver
EP0883327A2 (en) * 1997-06-03 1998-12-09 AKO-Werke GmbH & Co. KG Arrangement for wirelessly transmitting the temperature and for detecting the presence of cookware on a cooktop
US5952937A (en) * 1997-03-12 1999-09-14 Ut Automotive Dearborn, Inc. System and method of updating communications in a security system
US5986382A (en) * 1997-08-18 1999-11-16 X-Cyte, Inc. Surface acoustic wave transponder configuration
US5988510A (en) * 1997-02-13 1999-11-23 Micron Communications, Inc. Tamper resistant smart card and method of protecting data in a smart card
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
US6150921A (en) * 1996-10-17 2000-11-21 Pinpoint Corporation Article tracking system
US6208062B1 (en) 1997-08-18 2001-03-27 X-Cyte, Inc. Surface acoustic wave transponder configuration
US6259991B1 (en) 1999-02-10 2001-07-10 X-Cyte Inc. Environmental location system
US6273339B1 (en) 1999-08-30 2001-08-14 Micron Technology, Inc. Tamper resistant smart card and method of protecting data in a smart card
US6337659B1 (en) * 1999-10-25 2002-01-08 Gamma Nu, Inc. Phased array base station antenna system having distributed low power amplifiers
WO2002015115A1 (en) * 2000-08-15 2002-02-21 Kahl Elektrotechnik Gmbh Device for automatically identifying luggage provided with electronic tags
US20020075152A1 (en) * 2000-12-15 2002-06-20 Paul Nysen Apparatus and method for locating a tagged item
US6633226B1 (en) 1997-08-18 2003-10-14 X-Cyte, Inc. Frequency hopping spread spectrum passive acoustic wave identification device
US6775616B1 (en) 1999-02-10 2004-08-10 X-Cyte, Inc. Environmental location system
US6788204B1 (en) * 1999-03-15 2004-09-07 Nanotron Gesellschaft Fur Mikrotechnik Mbh Surface-wave transducer device and identification system with such device
US6812824B1 (en) 1996-10-17 2004-11-02 Rf Technologies, Inc. Method and apparatus combining a tracking system and a wireless communication system
US6825766B2 (en) 2001-12-21 2004-11-30 Genei Industries, Inc. Industrial data capture system including a choke point portal and tracking software for radio frequency identification of cargo
US20040246099A1 (en) * 1992-08-12 2004-12-09 Micron Technology, Inc. Miniature radio frequency transceiver
US20050092823A1 (en) * 2003-10-30 2005-05-05 Peter Lupoli Method and system for storing, retrieving, and managing data for tags
US20060017553A1 (en) * 2004-07-20 2006-01-26 Honeywell International, Inc. Encapsulated surface acoustic wave sensor
US20060175404A1 (en) * 2001-04-27 2006-08-10 Zierolf Joseph A Process and assembly for identifying and tracking assets
US20070007345A1 (en) * 1997-08-20 2007-01-11 Tuttle Mark E Electronic communication devices, methods of forming electrical communication devices, and communications methods
US20070042796A1 (en) * 2003-05-08 2007-02-22 Dirk Wenzel Method, system, base station and data carrier for clash-free transmission between a base station and a number of mobile data carriers
USRE40137E1 (en) 1997-05-01 2008-03-04 Micron Technology, Inc. Methods for forming integrated circuits within substrates
US20080271887A1 (en) * 1998-08-28 2008-11-06 Snider Philip M Method and system for performing operations and for improving production in wells
US20090223670A1 (en) * 2008-03-07 2009-09-10 Marathon Oil Company Systems, assemblies and processes for controlling tools in a well bore
US20090223663A1 (en) * 2008-03-07 2009-09-10 Marathon Oil Company Systems, assemblies and processes for controlling tools in a well bore
US20100013664A1 (en) * 1998-08-28 2010-01-21 Marathon Oil Company Method and apparatus for determining position in a pipe
US7956742B2 (en) 2003-10-30 2011-06-07 Motedata Inc. Method and system for storing, retrieving, and managing data for tags
USRE42773E1 (en) 1992-06-17 2011-10-04 Round Rock Research, Llc Method of manufacturing an enclosed transceiver
EP2444820A1 (en) * 2009-06-18 2012-04-25 Panasonic Corporation Moving object detection device
US8850899B2 (en) 2010-04-15 2014-10-07 Marathon Oil Company Production logging processes and systems
US20150351579A1 (en) * 2014-06-09 2015-12-10 Whirlpool Corporation Method of regulating temperature for sous vide cooking and apparatus therefor
DE102013010275C5 (en) * 2013-06-18 2016-09-15 Ika-Werke Gmbh & Co. Kg Magnetic stirrer with SAW sensor
US9730764B2 (en) 2015-10-02 2017-08-15 Elucent Medical, Inc. Signal tag detection components, devices, and systems
US9987097B2 (en) 2015-10-02 2018-06-05 Elucent Medical, Inc. Signal tag detection components, devices, and systems
US10154799B2 (en) 2016-08-12 2018-12-18 Elucent Medical, Inc. Surgical device guidance and monitoring devices, systems, and methods
US10278779B1 (en) 2018-06-05 2019-05-07 Elucent Medical, Inc. Exciter assemblies
US11344382B2 (en) 2014-01-24 2022-05-31 Elucent Medical, Inc. Systems and methods comprising localization agents

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3273146A (en) * 1964-08-07 1966-09-13 Gen Electric Object identifying apparatus

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3273146A (en) * 1964-08-07 1966-09-13 Gen Electric Object identifying apparatus

Cited By (141)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3750167A (en) * 1971-07-22 1973-07-31 Gen Dynamics Corp Postal tracking system
US3774205A (en) * 1971-08-02 1973-11-20 Ncr Co Merchandise mark sensing system
US3886548A (en) * 1973-10-12 1975-05-27 Boeing Co Responder for use in a passive identification system
US4019181A (en) * 1974-07-19 1977-04-19 U.S. Philips Corporation Transponder system
US4027840A (en) * 1974-10-15 1977-06-07 International Standard Electric Corporation Vehicle position indicator with radar interrogation each of spaced transponders disposed along a pathway for the vehicle
US3981011A (en) * 1975-03-31 1976-09-14 Sperry Rand Corporation Object identification system using an RF roll-call technique
US4059831A (en) * 1975-10-06 1977-11-22 Northwestern University Passive transponders using acoustic surface wave devices
US4096477A (en) * 1975-10-06 1978-06-20 Northwestern University Identification system using coded passive transponders
US4242671A (en) * 1977-12-09 1980-12-30 Plows Graham S Transponders
EP0002595A1 (en) * 1977-12-09 1979-06-27 Lintech Instruments Limited Transponders
EP0005534A1 (en) * 1978-05-16 1979-11-28 Siemens Aktiengesellschaft Device for identifying objects and persons
US4263595A (en) * 1978-05-16 1981-04-21 Siemens Aktiengesellschaft Apparatus for identifying objects and persons
DE3102334A1 (en) * 1980-01-25 1981-12-10 Unisearch Ltd., Kensington, New South Wales TEMPERATURE REMOTE MEASURING DEVICE
US4399441A (en) * 1980-01-25 1983-08-16 Unisearch Limited Apparatus for remote temperature reading
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
US4625208A (en) * 1983-06-30 1986-11-25 X-Cyte Inc. Surface acoustic wave passive transponder having acoustic wave reflectors
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
EP0240761A1 (en) * 1983-07-01 1987-10-14 M & FC HOLDING COMPANY, INC. Meter data gathering and transmission system
US4807140A (en) * 1983-11-10 1989-02-21 Saulnier Dominique C Electronic label information exchange system
US4658252A (en) * 1984-08-13 1987-04-14 Gte Government Systems Corporation Encoder/decoder for card entry system
AU568157B2 (en) * 1984-10-09 1987-12-17 X-Cyte Inc. Compensating for non-linear frequency variation in a system for interrogating a transponder
JPH0644039B2 (en) 1984-10-09 1994-06-08 エックス−サイト インコ−ポレ−テッド Surface acoustic wave passive transponder with amplitude and phase changing surface pads
DE3438052A1 (en) * 1984-10-09 1986-04-24 X-Cyte, Inc., Mountain View, Calif. SYSTEM FOR INQUIRING A PASSIVE, PHASE-CODED INFORMATION WITH TRANSPONDER
GB2165411A (en) * 1984-10-09 1986-04-09 X Cyte Inc Surface acoustic wave passive transponder having amplitude and phase-modifying surface pads
US4734698A (en) * 1985-10-31 1988-03-29 X-Cyte, Inc. Passive interrogator label system having offset compensation and temperature compensation for a surface acoustic wave transponder
US4746830A (en) * 1986-03-14 1988-05-24 Holland William R Electronic surveillance and identification
JPS6363875A (en) * 1986-09-04 1988-03-22 株式会社ゼネラルリサ−チオブエレクトロニツクス Key device
US4698631A (en) * 1986-12-17 1987-10-06 Hughes Tool Company Surface acoustic wave pipe identification system
US4980680A (en) * 1988-08-02 1990-12-25 Gte Products Corp. And Gte Laboratories, Inc. Coded surface acoustical wave (saw) motor vehicle security device
US4931664A (en) * 1988-08-02 1990-06-05 Gte Products Corporation Controller for coded surface acoustical wave (SAW) security system
WO1990004794A1 (en) * 1988-10-27 1990-05-03 Micro Design A.S. Method for processing transmitted and reflected signals for removing unwanted signals and noise from wanted signals
AU625991B2 (en) * 1988-10-27 1992-07-23 Q-Free Asa Method for processing transmitted and reflected signals for removing unwanted signals and noise from wanted signals
US4945354A (en) * 1988-11-25 1990-07-31 Gte Products Spurious signal correction for surface acoustic wave (SAW) security devices
EP0413634A3 (en) * 1989-08-17 1994-10-19 Mitsubishi Heavy Ind Ltd Id card
EP0413634A2 (en) * 1989-08-17 1991-02-20 Mitsubishi Jukogyo Kabushiki Kaisha ID card
US5130522A (en) * 1989-08-17 1992-07-14 Mitsubishi Jukogyo Kabushiki Kaisha Id card using surface acoustic waves
US5115160A (en) * 1989-08-28 1992-05-19 Gte Products Easily encodable surface acoustic wave (SAW) security devices
US6220516B1 (en) 1992-06-17 2001-04-24 Micron Technology, Inc. Method of manufacturing an enclosed transceiver
US6078791A (en) * 1992-06-17 2000-06-20 Micron Communications, Inc. Radio frequency identification transceiver and antenna
US5448110A (en) * 1992-06-17 1995-09-05 Micron Communications, Inc. Enclosed transceiver
USRE42773E1 (en) 1992-06-17 2011-10-04 Round Rock Research, Llc Method of manufacturing an enclosed transceiver
US6325294B2 (en) 1992-06-17 2001-12-04 Micron Technology, Inc. Method of manufacturing an enclosed transceiver
US5776278A (en) * 1992-06-17 1998-07-07 Micron Communications, Inc. Method of manufacturing an enclosed transceiver
US5779839A (en) * 1992-06-17 1998-07-14 Micron Communications, Inc. Method of manufacturing an enclosed transceiver
US8018340B2 (en) 1992-08-12 2011-09-13 Round Rock Research, Llc System and method to track articles at a point of origin and at a point of destination using RFID
US20040246099A1 (en) * 1992-08-12 2004-12-09 Micron Technology, Inc. Miniature radio frequency transceiver
US7746230B2 (en) * 1992-08-12 2010-06-29 Round Rock Research, Llc Radio frequency identification device and method
US5497140A (en) * 1992-08-12 1996-03-05 Micron Technology, Inc. Electrically powered postage stamp or mailing or shipping label operative with radio frequency (RF) communication
US7649463B2 (en) 1992-08-12 2010-01-19 Keystone Technology Solutions, Llc Radio frequency identification device and method
US6013949A (en) * 1992-08-12 2000-01-11 Micron Technology, Inc. Miniature Radio Frequency Transceiver
US7583192B2 (en) * 1992-08-12 2009-09-01 Keystone Technology Solutions, Llc Radio frequency identification device and method
US20070290863A1 (en) * 1992-08-12 2007-12-20 Tuttle John R Radio Frequency Identification Device And Method
US7265674B2 (en) 1992-08-12 2007-09-04 Micron Technology, Inc. Thin flexible, RFID labels, and method and apparatus for use
US20050285744A1 (en) * 1992-08-12 2005-12-29 Tuttle John R Radio frequency identification device and system including automatic sorting machine
US7158031B2 (en) 1992-08-12 2007-01-02 Micron Technology, Inc. Thin, flexible, RFID label and system for use
US5423334A (en) * 1993-02-01 1995-06-13 C. R. Bard, Inc. Implantable medical device characterization system
WO1994023981A1 (en) * 1993-04-08 1994-10-27 Siemens Aktiengesellschaft Obstacle-detection device
US5469170A (en) * 1994-10-20 1995-11-21 The United States Of America As Represented By The Secretary Of The Army Passive SAW-ID tags using a chirp transducer
US6150921A (en) * 1996-10-17 2000-11-21 Pinpoint Corporation Article tracking system
US6812824B1 (en) 1996-10-17 2004-11-02 Rf Technologies, Inc. Method and apparatus combining a tracking system and a wireless communication system
US6483427B1 (en) 1996-10-17 2002-11-19 Rf Technologies, Inc. Article tracking system
US7741956B1 (en) 1996-11-29 2010-06-22 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
US6531957B1 (en) * 1996-11-29 2003-03-11 X-Cyte, Inc. Dual mode transmitter-receiver and decoder for RF transponder tags
US6107910A (en) * 1996-11-29 2000-08-22 X-Cyte, Inc. Dual mode transmitter/receiver and decoder for RF transponder tags
US6068192A (en) * 1997-02-13 2000-05-30 Micron Technology, Inc. Tamper resistant smart card and method of protecting data in a smart card
US5988510A (en) * 1997-02-13 1999-11-23 Micron Communications, Inc. Tamper resistant smart card and method of protecting data in a smart card
US5952937A (en) * 1997-03-12 1999-09-14 Ut Automotive Dearborn, Inc. System and method of updating communications in a security system
USRE40137E1 (en) 1997-05-01 2008-03-04 Micron Technology, Inc. Methods for forming integrated circuits within substrates
US6075463A (en) * 1997-06-03 2000-06-13 Ako-Werke Gmbh & Co. Kg Apparatus for wirelessly transmitting the temperature and an identifying characteristic of a cooking pot to a stove
EP0883327A3 (en) * 1997-06-03 1999-05-19 AKO-Werke GmbH & Co. KG Arrangement for wirelessly transmitting the temperature and for detecting the presence of cookware on a cooktop
EP0883327A2 (en) * 1997-06-03 1998-12-09 AKO-Werke GmbH & Co. KG Arrangement for wirelessly transmitting the temperature and for detecting the presence of cookware on a cooktop
US6114971A (en) * 1997-08-18 2000-09-05 X-Cyte, Inc. Frequency hopping spread spectrum passive acoustic wave identification device
US6633226B1 (en) 1997-08-18 2003-10-14 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
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
US7132778B1 (en) 1997-08-18 2006-11-07 X-Cyte, Inc. Surface acoustic wave modulator
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
US7948382B2 (en) 1997-08-20 2011-05-24 Round Rock Research, Llc Electronic communication devices, methods of forming electrical communication devices, and communications methods
US20070007345A1 (en) * 1997-08-20 2007-01-11 Tuttle Mark E Electronic communication devices, methods of forming electrical communication devices, and communications methods
US20070290862A1 (en) * 1997-08-20 2007-12-20 Tuttle Mark E Electronic Communication Devices, Methods Of Forming Electrical Communication Devices, And Communications Methods
US7839285B2 (en) 1997-08-20 2010-11-23 Round Rock Resarch, LLC Electronic communication devices, methods of forming electrical communication devices, and communications methods
US20080271887A1 (en) * 1998-08-28 2008-11-06 Snider Philip M Method and system for performing operations and for improving production in wells
US9140818B2 (en) 1998-08-28 2015-09-22 Marathon Oil Company Method and apparatus for determining position in a pipe
US8044820B2 (en) 1998-08-28 2011-10-25 Marathon Oil Company Method and system for performing operations and for improving production in wells
US7714741B2 (en) 1998-08-28 2010-05-11 Marathon Oil Company Method and system for performing operations and for improving production in wells
US20100013664A1 (en) * 1998-08-28 2010-01-21 Marathon Oil Company Method and apparatus for determining position in a pipe
US6775616B1 (en) 1999-02-10 2004-08-10 X-Cyte, Inc. Environmental location system
US6259991B1 (en) 1999-02-10 2001-07-10 X-Cyte Inc. Environmental location system
US6788204B1 (en) * 1999-03-15 2004-09-07 Nanotron Gesellschaft Fur Mikrotechnik Mbh Surface-wave transducer device and identification system with such device
US6273339B1 (en) 1999-08-30 2001-08-14 Micron Technology, Inc. Tamper resistant smart card and method of protecting data in a smart card
US6337659B1 (en) * 1999-10-25 2002-01-08 Gamma Nu, Inc. Phased array base station antenna system having distributed low power amplifiers
WO2002015115A1 (en) * 2000-08-15 2002-02-21 Kahl Elektrotechnik Gmbh Device for automatically identifying luggage provided with electronic tags
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
US20060175404A1 (en) * 2001-04-27 2006-08-10 Zierolf Joseph A Process and assembly for identifying and tracking assets
US7677439B2 (en) 2001-04-27 2010-03-16 Marathon Oil Company Process and assembly for identifying and tracking assets
US20100171593A1 (en) * 2001-04-27 2010-07-08 Marathon Oil Company Process and assembly for identifying and tracking assets
US8091775B2 (en) 2001-04-27 2012-01-10 Marathon Oil Company Process and assembly for identifying and tracking assets
US6825766B2 (en) 2001-12-21 2004-11-30 Genei Industries, Inc. Industrial data capture system including a choke point portal and tracking software for radio frequency identification of cargo
US7587050B2 (en) * 2003-05-08 2009-09-08 Nxp B.V. Method, system, base station and data carrier for clash-free transmission between a base station and a number of mobile data carriers
US20070042796A1 (en) * 2003-05-08 2007-02-22 Dirk Wenzel Method, system, base station and data carrier for clash-free transmission between a base station and a number of mobile data carriers
US20050092823A1 (en) * 2003-10-30 2005-05-05 Peter Lupoli Method and system for storing, retrieving, and managing data for tags
US20080224857A1 (en) * 2003-10-30 2008-09-18 Peter Lupoli Method and system for storing, retrieving, and managing data for tags
US7388488B2 (en) 2003-10-30 2008-06-17 Peter Lupoli Method and system for storing, retrieving, and managing data for tags
US7956742B2 (en) 2003-10-30 2011-06-07 Motedata Inc. Method and system for storing, retrieving, and managing data for tags
US8558668B2 (en) 2003-10-30 2013-10-15 Motedata Inc. Method and system for storing, retrieving, and managing data for tags
US20060017553A1 (en) * 2004-07-20 2006-01-26 Honeywell International, Inc. Encapsulated surface acoustic wave sensor
US7129828B2 (en) * 2004-07-20 2006-10-31 Honeywell International Inc. Encapsulated surface acoustic wave sensor
US10107071B2 (en) 2008-03-07 2018-10-23 Weatherford Technology Holdings, Llc Systems, assemblies and processes for controlling tools in a well bore
US20090223670A1 (en) * 2008-03-07 2009-09-10 Marathon Oil Company Systems, assemblies and processes for controlling tools in a well bore
US9194227B2 (en) 2008-03-07 2015-11-24 Marathon Oil Company Systems, assemblies and processes for controlling tools in a wellbore
US10119377B2 (en) 2008-03-07 2018-11-06 Weatherford Technology Holdings, Llc Systems, assemblies and processes for controlling tools in a well bore
US20090223663A1 (en) * 2008-03-07 2009-09-10 Marathon Oil Company Systems, assemblies and processes for controlling tools in a well bore
EP2444820A1 (en) * 2009-06-18 2012-04-25 Panasonic Corporation Moving object detection device
EP2444820A4 (en) * 2009-06-18 2014-03-26 Panasonic Corp Moving object detection device
US8850899B2 (en) 2010-04-15 2014-10-07 Marathon Oil Company Production logging processes and systems
DE102013010275C5 (en) * 2013-06-18 2016-09-15 Ika-Werke Gmbh & Co. Kg Magnetic stirrer with SAW sensor
US11344382B2 (en) 2014-01-24 2022-05-31 Elucent Medical, Inc. Systems and methods comprising localization agents
US10085584B2 (en) * 2014-06-09 2018-10-02 Whirlpool Corporation Method of regulating temperature for sous vide cooking and apparatus therefor
US20150351579A1 (en) * 2014-06-09 2015-12-10 Whirlpool Corporation Method of regulating temperature for sous vide cooking and apparatus therefor
US10292521B2 (en) 2014-06-09 2019-05-21 Whirlpool Corporation Method of regulating temperature for sous vide cooking and apparatus therefor
US20190223647A1 (en) * 2014-06-09 2019-07-25 Whirlpool Corporation Method of regulating temperature for sous vide cooking and apparatus therefor
US9730764B2 (en) 2015-10-02 2017-08-15 Elucent Medical, Inc. Signal tag detection components, devices, and systems
US9987097B2 (en) 2015-10-02 2018-06-05 Elucent Medical, Inc. Signal tag detection components, devices, and systems
US10245119B2 (en) 2015-10-02 2019-04-02 Elucent Medical, Inc. Signal tag detection components, devices, and systems
US10245118B2 (en) 2015-10-02 2019-04-02 Elucent Medical, Inc. Signal tag detection components, devices, and systems
US11786333B2 (en) 2015-10-02 2023-10-17 Elucent Medical, Inc. Signal tag detection components, devices, and systems
US10751145B2 (en) 2015-10-02 2020-08-25 Elucent Medical, Inc. Signal tag detection components, devices, and systems
US11135034B2 (en) 2015-10-02 2021-10-05 Elucent Medical, Inc. Signal tag detection components, devices, and systems
US10154799B2 (en) 2016-08-12 2018-12-18 Elucent Medical, Inc. Surgical device guidance and monitoring devices, systems, and methods
US11298044B2 (en) 2016-08-12 2022-04-12 Elucent Medical, Inc. Surgical device guidance and monitoring devices, systems, and methods
US11185375B2 (en) 2018-06-05 2021-11-30 Elucent Medical, Inc. Exciter assemblies
US11540885B2 (en) 2018-06-05 2023-01-03 Elucent Medical, Inc. Orthogonally isolated exciter with field steering
US11666391B2 (en) 2018-06-05 2023-06-06 Elucent Medical, Inc. Exciter assemblies
US10278779B1 (en) 2018-06-05 2019-05-07 Elucent Medical, Inc. Exciter assemblies

Similar Documents

Publication Publication Date Title
US3706094A (en) Electronic surveillance system
US4399441A (en) Apparatus for remote temperature reading
US3707711A (en) Electronic surveillance system
US3755803A (en) Electronic surveillance system
US3774205A (en) Merchandise mark sensing system
US3521280A (en) Coded labels
US6894614B2 (en) Radio frequency detection and identification system
US5214410A (en) Location of objects
US5469170A (en) Passive SAW-ID tags using a chirp transducer
CN102017437B (en) Anti-tamper cargo container locator system
US3273146A (en) Object identifying apparatus
US6657580B1 (en) Transponders
AU570891B2 (en) Electronic surveillance system employing the doppler effect
US6249229B1 (en) Electronic article security system employing variable time shifts
US5359250A (en) Bulk wave transponder
US3818472A (en) R.f. system for detecting unauthorized travel of articles through a selected zone
US20090091454A1 (en) Method and System to Determine Physical Parameters as Between A RFID Tag and a Reader
US20060192655A1 (en) Radio frequency identification of tagged articles
EP0578701A1 (en) Article sorting system
Buff et al. Remote sensor system using passive SAW sensors
CN101341661B (en) Multi-functional system for extending and modulating 130dbm frequency of GPS terminal for life jacket
CN105117764B (en) A kind of high-performance anticollision SAW delay line type wireless sensor system
ATE29182T1 (en) DETECTION SYSTEM.
WO1986002186A1 (en) Identification system
GB1298381A (en) Passive labels for use in electronic surveillance systems