EP0577687A1 - Appareil et methode d'identification - Google Patents

Appareil et methode d'identification

Info

Publication number
EP0577687A1
EP0577687A1 EP92907634A EP92907634A EP0577687A1 EP 0577687 A1 EP0577687 A1 EP 0577687A1 EP 92907634 A EP92907634 A EP 92907634A EP 92907634 A EP92907634 A EP 92907634A EP 0577687 A1 EP0577687 A1 EP 0577687A1
Authority
EP
European Patent Office
Prior art keywords
signal
modulation
modulations
predetermined
remote
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.)
Withdrawn
Application number
EP92907634A
Other languages
German (de)
English (en)
Inventor
David Robert Brooks
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.)
Magellan Corp Australia Pty Ltd
Original Assignee
Magellan Corp Australia Pty Ltd
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 Magellan Corp Australia Pty Ltd filed Critical Magellan Corp Australia Pty Ltd
Publication of EP0577687A1 publication Critical patent/EP0577687A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/69—Spread spectrum techniques
    • H04B1/707—Spread spectrum techniques using direct sequence modulation
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO 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
    • G01S13/00—Systems 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
    • G01S13/74—Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems
    • G01S13/75—Systems 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
    • G01S13/751—Systems 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
    • G01S13/758—Systems 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 a signal generator powered by the interrogation signal
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO 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
    • G01S13/00—Systems 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
    • G01S13/74—Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems
    • G01S13/82—Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems wherein continuous-type signals are transmitted
    • G01S13/825—Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems wherein continuous-type signals are transmitted with exchange of information between interrogator and responder
    • G—PHYSICS
    • G06—COMPUTING OR CALCULATING; COUNTING
    • G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
    • G06K7/00—Methods or arrangements for sensing record carriers, e.g. for reading patterns
    • G06K7/0008—General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J13/00—Code division multiplex systems
    • H04J13/10—Code generation

Definitions

  • the present invention relates to the field of identification of and/or communication between a number of remote objects or devices and an interrogator or receiver simultaneously.
  • the present invention deals with communication and/or identification of one or more remote devices, such as transponders.
  • the present invention also relates to a modification of the invention disclosed in the above related patent application. BACKGROUND ART
  • the related application disclosed a system adapted to identify one or more remote transponders simultaneously.
  • the system disclosed utilized a number of remote transponders, each of which transmit a data or information signal at a carrier frequency selected randomly from a group of possible carrier frequencies. At each transmission a newly selected carrier frequency is used.
  • the present invention relates to a device in which communication is provided between the device and a receiver or interrogator by use of a single carrier frequency in conjunction with a selected modulation, such as a Direct-Sequence Spread Spectrum modulation technique.
  • the present invention provides a device comprising: transmitter means adapted to transmit an information, code or identification signal; selection means adapted to select a modulation for transmission of said signal from a set of predetermined modulations; wherein the signal is transmitted using the selected modulation.
  • the present invention also provides a communication system comprising: at least one remote device each adapted to transmit a signal at a modulation selected from a set of predetermined modulations; and a receiver adapted to receive transmissions from at least one remote device.
  • the present invention preferably includes generating means for generation a set of predetermined modulations.
  • the device may also include means for extracting timing information or powering energy from an impinging electro-magnetic field.
  • control means is provided to select a modulation.
  • the control means may also reselect the same or another modulation for the next transmission.
  • the selection or reselection may occur in accordance with a probability weighting, pseudo ⁇ random binary sequence or may be random.
  • the present invention also provides a system for simultaneously identifying a first and second device, each device comprising code storage means, modulation means and an inductive receiver/transmitter means, the system comprising: magnetic field generator/radiator means for generating a magnetic field from which said first and second devices are adapted to extract power using said inductive means; each of said first and second devices, when so powered, respectively providing at least one unique code from the code storage means to the modulation means, said modulation means being adapted to provide at least one modulated code to the inductive means for transmission to a device identifying receiver; each device adapted to modulate said at least one code at at least one modulation randomly selected from a predetermined finite set of modulations, while each device remains powered; each device being embodied in a single (IC) chip.
  • IC single
  • the present invention further provides a method of communication between an interrogator and at least two remote receiving devices, said method comprising the steps of: radiating an interrogation signal from said interrogator to each remote device; generating a reply signal at a modulation selected from a predetermined set of modulations in each remote device; transmitting said reply signal from each remote device to the interrogator; and serially generating and transmitting the reply signal at a newly selected modulation from said predetermined set of modulations.
  • the interrogator of the communication system may also be adapted to receive a number of transmissions from any number of remote devices simultaneously, and demodulate the received transmissions to recover a signal from each remote device. This is made possible by having an interrogator adapted to receive a number of different modulations simultaneously.
  • the interrogator comprises a number of modulation receiving channels, the number of channels corresponding to the number of modulations available for selection for transmission of data by a remote device.
  • the signal may be an identification, code and/or information signal.
  • the signal is preferably RF.
  • Figure 1 shows a prior art DSSS transmitter
  • Figure 2 shows a prior art DSSS receiver
  • Figure 3 shows a device incorporating a transmitter according to the present invention
  • Figure 4 shows a preferred form of PN generator
  • Figure 5 shows a receiver according to the present invention.
  • the preferred embodiment to be described operates on principles similar to those described in the aforementioned related application.
  • any communication apparatus is also encompassed, including transponders and transmitter/receiver systems.
  • the term “device” should therefore be given a broad interpretation the “device” may be passive or active.
  • the term “modulation” is also intended to be construed broadly and encompass many forms of communication mediums, including a PN sequence.
  • the term “interrogator” should also be interrupted broadly to include at least devices adapted to receive transmissions from and/or communicate with one or more remote devices.
  • the present invention in one form represents a modification or enhancement of the applicants related invention, whereby a single carrier frequency is used, in conjunction with a "Direct-Sequent Spread Spectrum” modulation technique.
  • a transmitter for a Direct-Sequence Spread Spectrum (DSSS) system includes a source of pseudo-random data (usually binary), such data being generated at a rate considerably in excess of the system communication speed. Because of its similarity to natural noise, this data is commonly termed “Pseudo-Noise” (PN). This PN data is then mixed with the "real" data, so greatly increasing the requisite bandwidth, and transmitted.
  • PN pseudo-random data
  • the receiver or interrogator of the present invention must include, on each channel means to generate a Pn-sequence identical to that used by a remote device. That is, the interrogator includes a separate channel for each possible Pn-sequence which can be selected by a remote device.
  • the Pn-sequence of each channel needs to be accurately synchronised with that of the transmitting remote device. Means for achieving such synchronisation are known (see, inter alia, Sklar, "Digitals Communications: Fundamentals & Applications", Prentice-Hall, 1988). To be effective, synchronisation needs to be very precise (within a fraction of the period of the clock driving the PN generator).
  • the desired signal is greatly increased in amplitude, while other, un-synchronized signals are greatly attenuated.
  • the receiver's PN generator produce a PN sequenced different to that at the transmitter, synchronisation will be impossible. It is this selective amplification property which provides the basis for the present invention.
  • a correlation operation is performed between the received signal and this local PN source, leaving the required data or signal.
  • the present invention contemplates the use of a single carrier frequency for use by all remote devices, upon which a data or information signal is modulated in accordance with a particular type of modulation (AM, FM. etc) or in accordance with a particular pn-sequence.
  • the invention provides a device and an object-identification system, characterised by the ability to identify (read signals from) several different objects simultaneously.
  • Prior art systems employ a plurality of carrier radio frequencies, was described in the applicants related invention.
  • the related invention provided an identifying device ("transponder", or “tag”) to be attached to the object to be identified, said tag being adapted to transmit an identifying message at one of a plurality of radio frequencies. In use, the message is repeatedly transmitted, with the same or a new radio frequency being selected at each transmission.
  • the receiving equipment provides a plurality of channels, each sensitive to one of the plurality of frequencies, and can receive message on all frequencies simultaneously.
  • Separation of messages transmitted by a plurality of tags is provided by limiting the bandwidth of the receiver channels, such that each receives messages on one radio frequency only.
  • the system is characterised by the ability to identify a plurality of tags at once, such plurality being randomly selected from an extremely large (quasi-infinite) total population of possible tags.
  • the present invention may be regarded as an improvement over or a modification of the related invention.
  • a single radio frequency is used, and the tags are prevented from co-interfering by employing a plurality of PN sequences and/or a plurality of types of modulation and likewise a plurality of corresponding receivers, each such receiver adapted to synchronise to only one of the said plurality of PN sequences or types of modulation.
  • the transmitting portion of a device according to the present invention is shown conceptually in Fig. 3. Comparison with the prior art Fig. 1 will disclose the novelty, which resides in the provision of a plurality of PN or modulation sources, and a selection means (which said means operates identically to that of the cited prior invention) to choose one of the PN or modulation sources.
  • the tag selects a PN or type of modulation source, transmits the message, selects a new (or the same) PN or type of modulation source, and repeats.
  • a single PN generator adapted to receive as inputs, certain quantities ("co-efficients") which determine the generated sequence.
  • An exemplary embodiment of such a circuit is shown in Fig. 4.
  • the device comprises a shift register A, whose input is fed from the Exclusive-OR (XOR) function of two or more taps on the said shift register. Adroitly chosen taps will yield a plurality of long sequences, having good PN qualities.
  • the exemplary embodiment employs two taps, implemented by the multiplexers B and C, which select two bits from the said register, and present them to the XOR gate D. The output of this gate is presented to the serial data input of register A.
  • a plurality of PN sequences may be produced.
  • a plurality of such selections are pre- determined, and stored in the Read-Only-Memory (ROM) E.
  • ROM Read-Only-Memory
  • its outputs direct multiplexers B and C to select taps on the register A, and a PN sequence is generated.
  • a "selection means" is provided to select from the plurality of possible PN sequences.
  • a preferred receiving means are shown in Fig. 5.
  • Each of the several PN or modulation generators generates a different member of the plurality of PN sequences or modulations available in the device.
  • Suitable PN sequences can be characterised by 3 qualities:
  • the PN sequence shall comprise approximately equal numbers of ONE and ZERO bits.
  • the present system utilises the interference-resistant quality of a DSSS channel to identify or communicate with specific devices such as transponders.
  • each device is adapted to hold a plurality of distinct PN sequences as a set of predetermined modulations.
  • the device may hold a table of suitable coefficients, which may be passed to a digital logic circuit, such circuit being adapted to (when the said coefficients are presented as inputs) generate the required PN sequences or modulations.
  • a random or predetermined choice is made amongst these modulations and the randomly chosen modulation is used to transmit a signal which is to form the communication.
  • a new choice (from the available PN sequences) is made on a random or predetermined basis.
  • Each bit of the message data is mixed with the chosen PN sequence, and transmitted, in practice this may imply that what is transmitted is either a selected modulation or in the case of a stored sequence, its complement, depending on whether signal is a logic signal and the data bit is a zero or one.
  • the transmission bandwidth has been increased in proportion to the number of bits in the PN sequence.
  • in which only alternate bits of the PN sequence, rather than all bits are reversed to suit the data polarity.
  • Other schemes are also possible.
  • the complete message is transmitted preferably using a single modulation PN sequence.
  • the PN sequence may extend over the entire message, or a shorter PN sequence may be used repeatedly for each message bit.
  • a new sequence is then selected, from a group of available sequences, and the message is retransmitted.
  • the radio carrier frequency remains substantially constant.
  • the receiver or interrogator may operate on the homodyne principle as described on pages 14-15 and Figure 9 of the related application.
  • an interrogator will yield as output a wideband data stream, comprising the sum of messages received from all devices within range.
  • Such messages will have been encoded using the plurality of PN sequences as previously described.
  • This stream is passed simultaneously to a plurality of matched filters, each adapted to match one of the original, stored PN sequences.
  • filters may be of the class of "Transversal Filters", wherein the filter coefficients take the values +1 and -1 , following the bit-sequence of the original PN pattern.
  • the auto-correlation property of the PN sequences implies that when a data pattern matching the original sequence is presented to such a filter, a sharp positive voltage spike appears at the output, as the received data passes (momentarily) into alignment with the filter coefficients. Similarly the complement of the given sequence will develop a sharp negative pulse. Non-matched data will merely generate low-level noise, which may be filtered out by a simple amplitude "window", or other circuitry.
  • the pulses so obtained represent one and zero bits of the original data.
  • the above-described cross-correlation property of the PN sequences enables messages encoded with a given PN sequence to be recovered by the appropriate matched filter, and no other. This property serves to separate out the various transmissions from one or more devices.
  • these transversal filters may be implemented by converting the receiver output to a sampled digital representation, and employing one of the many "digital signal processor" VLSI chips now available, to perform the filtering function in the digital domain. Many such chips are sufficiently powerful to simultaneously filter a plurality of channels (i.e. using different PN sequences).
  • An interrogator as described above is suitable for a PN sequence, however, the interrogator may be suitably constructed or adapted to receive and demodulate any type of modulation, depending on the form of modulation selected to transmit the signal from the remote device(s) to the interrogator, as would be understood by those of the art.
  • Such a system could simultaneously identify very large numbers of transponders, in that it provides a system utilising a plurality P1 of radio frequencies, with a second plurality P2 of PN sequences employed upon each of the said frequencies, so obtaining a larger plurality (up to P1 * P2) of simultaneously useable channels. While such a system would require a more elaborate receiver means (having up to P1 * P2 receiving sections) than either of the description above, it would permit rapid, simultaneous identification of very large numbers of objections.
  • AM modulation
  • FM modulation say

Landscapes

  • Engineering & Computer Science (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Artificial Intelligence (AREA)
  • Computer Vision & Pattern Recognition (AREA)
  • Theoretical Computer Science (AREA)
  • Signal Processing (AREA)
  • Radar Systems Or Details Thereof (AREA)
  • Near-Field Transmission Systems (AREA)

Abstract

L'invention concerne un dispositif, un appareil d'identification et un procédé dans lesquels une seule fréquence de porteuse est utilisée par un nombre illimité de dispositifs éloignés. On module sur ladite porteuse des données ou des informations en vue de leur transmission à un interrogateur, la modulation étant sélectionnée arbitrairement parmi un groupe plus large de modulations disponibles. La modulation peut être de n'importe quel type, par exemple, AM, FM, PWM (modulation d'impulsions en largeur) ou peut être basé sur une séquence Pn ou une pluralité de séquences Pn différentes.
EP92907634A 1991-03-28 1992-03-24 Appareil et methode d'identification Withdrawn EP0577687A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
AUPK536691 1991-03-28
AU5366/91 1991-03-28

Publications (1)

Publication Number Publication Date
EP0577687A1 true EP0577687A1 (fr) 1994-01-12

Family

ID=3775306

Family Applications (1)

Application Number Title Priority Date Filing Date
EP92907634A Withdrawn EP0577687A1 (fr) 1991-03-28 1992-03-24 Appareil et methode d'identification

Country Status (4)

Country Link
EP (1) EP0577687A1 (fr)
CA (1) CA2103910A1 (fr)
WO (1) WO1992017947A1 (fr)
ZA (1) ZA922184B (fr)

Families Citing this family (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4242973C2 (de) * 1992-12-18 1995-01-05 Grundig Emv Funkalarmanlage mit einer Vielzahl von nach dem Code-Multiplexverfahren gebildeten Nachrichtenkanälen
DE4337637A1 (de) * 1993-11-04 1995-05-11 Licentia Gmbh Transponder und Datenkommunikationssystem
EP1333606A3 (fr) * 1994-09-09 2004-05-19 XIRCOM Wireless, Inc. Transmission de communications à spectre étalé et à modulation CPM
US5649295A (en) * 1995-06-19 1997-07-15 Lucent Technologies Inc. Dual mode modulated backscatter system
US5649296A (en) * 1995-06-19 1997-07-15 Lucent Technologies Inc. Full duplex modulated backscatter system
US5940006A (en) * 1995-12-12 1999-08-17 Lucent Technologies Inc. Enhanced uplink modulated backscatter system
US6130602A (en) 1996-05-13 2000-10-10 Micron Technology, Inc. Radio frequency data communications device
KR20000049066A (ko) * 1996-10-17 2000-07-25 핀포인트 코포레이션 물품검색 시스템
KR100326182B1 (ko) * 1998-03-23 2002-07-02 윤종용 부호분할다중접속통신시스템의의사잡음시퀀스발생방법및장치
JP4259746B2 (ja) * 2000-12-15 2009-04-30 イビデン株式会社 受信波送信装置および移動体識別システム
FR2871312B1 (fr) * 2004-06-03 2006-08-11 St Microelectronics Sa Modulation de charge dans un transpondeur electromagnetique

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4218680A (en) * 1979-01-12 1980-08-19 Motorola, Inc. Coded coherent transponder
IL78972A (en) * 1985-06-14 1991-04-15 Mitsubishi Electric Sales Amer Video optimized modulator-demodulator
US4746880A (en) * 1987-02-06 1988-05-24 Digital Rf Solutions Corporation Number controlled modulated oscillator
WO1989005549A1 (fr) * 1987-12-04 1989-06-15 Magellan Corporation (Australia) Pty. Ltd. Appareil et procedes d'identification

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9217947A1 *

Also Published As

Publication number Publication date
ZA922184B (en) 1992-12-30
WO1992017947A1 (fr) 1992-10-15
CA2103910A1 (fr) 1992-09-29

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