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WO2006105565A1 - Procede pour la demodulation et lecteur pour evaluer des signaux a modulation de charge - Google Patents

Procede pour la demodulation et lecteur pour evaluer des signaux a modulation de charge Download PDF

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Publication number
WO2006105565A1
WO2006105565A1 PCT/AT2006/000132 AT2006000132W WO2006105565A1 WO 2006105565 A1 WO2006105565 A1 WO 2006105565A1 AT 2006000132 W AT2006000132 W AT 2006000132W WO 2006105565 A1 WO2006105565 A1 WO 2006105565A1
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WO
WIPO (PCT)
Prior art keywords
signal
sub
carrier signal
subcarrier
signals
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/AT2006/000132
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German (de)
English (en)
Inventor
Georg Brasseur
Hubert Zangl
Thomas Bretterklieber
Andreas Haderer
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.)
Technische Universitaet Graz
Original Assignee
Technische Universitaet Graz
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 Technische Universitaet Graz filed Critical Technische Universitaet Graz
Publication of WO2006105565A1 publication Critical patent/WO2006105565A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • 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
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/18—Phase-modulated carrier systems, i.e. using phase-shift keying
    • H04L27/22—Demodulator circuits; Receiver circuits
    • H04L27/233—Demodulator circuits; Receiver circuits using non-coherent demodulation
    • H04L27/2331—Demodulator circuits; Receiver circuits using non-coherent demodulation wherein the received signal is demodulated using one or more delayed versions of itself

Definitions

  • the invention relates to a method for the demodulation of load-modulated signals in a system in which a reading device delivers a high-frequency carrier signal to a transmitting antenna, passive transponders in the area of influence of the antenna receive the signal and load-modulate the received signal and in the reading device the retroactively modulated RF Signal is demodulated to evaluate the modulation signal.
  • the invention relates to a reading device for evaluating load-modulated signals, with an RF generator for supplying an antenna with a carrier signal, a demodulation circuit and an evaluation circuit.
  • Transponders and readers commonly referred to in English as “RFID tags” and “readers”, are known and used in many fields, e.g. Systems and application examples are described, for example, in “RFID Handbook” Klaus Finkenzeller, John Wiley & Sons, Ltd., Second Edition 2003, ISBN 0-470-84402-7.
  • FIG. A prior art system for reading tags is shown in FIG.
  • a reading device LES (Reader) with transmitting antenna supplied via a magnetic alternating field, eg. B. in 13.56 MHz band, on the one hand transponder (tags) TRA, which also have an antenna, with energy (passive tags) and on the other hand, the reader LES can communicate with the transponder TRA (downlink).
  • the recorded by a transponder TRA RF signal is rectified and with the rectified voltage can z.
  • B. an energy storage to supply the transponder electronics are charged. If a transponder has absorbed enough energy, it can receive signals from a reader. However, it can also send signals to the reader using a load modulation retroactively applied to the carrier (uplink). Such a load modulation is described in connection with Figure 3.16 on page 45 in the aforementioned "RFID Handbook".
  • a load modulation causes the uplink in the reader a signal that can occur in different modes, either as amplitude modulation or as a phase modulation or as a hybrid of the two types of modulation. If a signal with amplitude modulation is present, the demodulation with little technical effort with the aid of an amplitude demodulator (eg peak detector, envelope demodulator, diode decoder) gate) possible. However, this method fails for signals that are predominantly phase-modulated.
  • amplitude demodulator eg peak detector, envelope demodulator, diode decoder
  • Figs. 2a and 2b show the case of pure amplitude modulation.
  • the carrier signal ST and the modulation signal S M are in phase and constructively overlap one another to form a resulting signal SR.
  • carriers ST and modulation SM destructively interfere with each other to a signal SR.
  • the signal S M occurs as an amplitude modulation in the signal SR.
  • Figs. 3a and 3b show the case of pure phase modulation.
  • the modulation S M is lagging by 90 degrees with respect to the carrier ST, resulting in a resultant signal SR.
  • the modulation SM is advanced by 90 degrees with respect to the carrier ST and a signal SR results.
  • the lengths of the resulting pointers in FIGS. 3a and 3b do not differ, so that the modulation is not recognizable in amplitude either.
  • the prior art knows two methods for the mode-independent demodulation of load modulated signals.
  • the first method uses synchronous sampling, placing high demands on the electronics.
  • the second method uses a cable of a certain length to achieve a mode conversion (from phase modulation to amplitude modulation), thereby enabling cost effective demodulation, for example, by means of diodes.
  • a mode conversion can also be realized by means of filters.
  • filters must show a very pronounced frequency response in order to achieve the desired mode conversion. ken, which alone is connected because of the temperature dependence of the electronic components with considerable technical effort.
  • I and Q signals are determined by means of a zero-cross detector module, a phase shifter and choppers and filter components and the demodulation is carried out with the aid of a mixer, wherein the mixture is carried out with two scanning signals shifted by 90 °.
  • I and Q channel can be realized with a simple envelope demodulator (eg diode with filter capacitor). Even zero-cross detectors and fast switches (choppers) are not needed.
  • I and Q are sampled by tapping at specific locations within the signal path. With the aid of these signals, a sampling (sampling) takes place, there is thus a synchronous sampling with two scanning signals shifted by 90 °. Such a sampling also applies to WO 02/23465 A2, according to which a suitable sampling time is determined in order to successfully demodulate both in phase and amplitude modulation.
  • synchronous sampling provides US 6028503, according to which only a synchronous demodulator is used whose sampling times are shifted depending on the phase position of the signal to be detected.
  • WO 96/18969 describes a method for the demodulation of signals with possible occurrence of both types of modulation, the demodulation taking place with the aid of a phase demodulator, also in conjunction with an envelope demodulator.
  • JP 63052082 discloses a method in which I and Q signals are derived from the modulated signal with the aid of two mixers, the signals obtained subsequently being fed to an envelope demodulator and the stronger of the two output signals being used for further processing.
  • An object of the invention is to demodulate load-modulated signals with little effort, both in terms of cost and physical dimensions.
  • a suitable further processing provides that of the two demodulated signals selected that with the higher signal quality and further processed for evaluation.
  • the flexibility of the processing is increased if at least one of the demodulated signals is subjected to analog-to-digital conversion.
  • phase angle between the carrier signal and subcarrier is selected in a range of 120 ° to 150 °.
  • the object underlying the invention is achieved with a reading device of the subject type, which is characterized by an auxiliary signal generator for generating a frequency-synchronous to the carrier signal, shifted by a phase angle subcarrier, a summing circuit for summing the carrier signal with the subcarrier and a demodulator for demodulating the carrier signal applied to the antenna, and a demodulator for demodulating the sum signal generated in the summing circuit.
  • An advantageous development of a reading device is characterized in that a selection circuit is provided, to which the two signals demodulated in the demodulators are fed and whose output signal is fed to the evaluation circuit.
  • FIG. 1 schematically shows a system with readable, passive transponders, as it corresponds to the prior art
  • Fig. 5 is a block diagram of a reading device according to the invention.
  • FIGS. 4 a, 4b and 5 wherein first the block diagram of FIG. 5 is prefixed.
  • An RF generator GEN fed with a frequency fo possibly via a driver amplifier VER with a carrier signal S T an antenna ANT, in whose magnetic field, one (or more) transponder TRA may be.
  • auxiliary signal generator HSG which is also fed by the RF generator GEN, a frequency-synchronous to the carrier signal ST to a phase angle ⁇ shifted subcarrier S H is generated.
  • the auxiliary signal generator HSG contains a controllable phase senschieber, in response to him supplied signals, namely the carrier signal ST and a resulting sum signal SR (see below) a 90 ° phase between the carrier signal and the resulting sum signal SR (see below Fig. 4a, b) adjusts.
  • the output signal of the auxiliary signal generator HSG, the subcarrier SH is supplied together with the carrier signal ST a summing SUM.
  • the carrier signal S T is supplied to a demodulator DEI and the subcarrier S H or subcarrier signal to a demodulator DEQ.
  • Both demodulators can be simple envelope demodulators based on a diode.
  • the output signals of the demodulators DIE, DEQ, the demodulated signals si, SQ are performed, optionally after an analog / digital conversion in an analog / digital converter ADW to a selection circuit SEL, which z. B. selected on the basis of known signal quality criteria that signal which is best suited for further processing.
  • This selected signal S n is used in an evaluation circuit ASW in a known manner, for. For identification of tickets, goods etc.
  • FIG. 4 a The method used is shown in FIG. 4 a at a first time and in FIG. 4 b at a second time in analogy to FIGS. 2 and 3. While the load-modulated signal SM remains unchanged from the addition, the carrier SR resulting from the carrier signal ST and the subcarrier SH, which is now amplitude-modulated in the illustrated case, rotates its position. Both the sum signal and the unchanged carrier are, as described above, supplied to a simple diode demodulator. The described method ensures that at least in one of the two channels I, Q, the load-modulated signal occurs as an amplitude modulation and the demodulation is successful even with only one diode.
  • the auxiliary carrier With the help of the auxiliary carrier, the resulting sum signal compared to the original signal (Fig. 3) but also be reduced, while the load-modulated signal remains unchanged.
  • the ratio of amplitudes of the load-modulated signal S M and the resulting sum signal SR is referred to as the degree of modulation or modulation index.
  • a higher degree of modulation is advantageous in demodulation.
  • other sums can be formed with additional auxiliary carriers.
  • the subcarrier may have exactly reversed phase of the carrier and thus also be used in an event as shown in Fig. 4 to increase the modulation index.
  • auxiliary signal generator HSG phase shifter

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Artificial Intelligence (AREA)
  • Computer Vision & Pattern Recognition (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Digital Transmission Methods That Use Modulated Carrier Waves (AREA)
  • Near-Field Transmission Systems (AREA)

Abstract

L'invention concerne un procédé pour la démodulation de signaux à modulation de charge dans un système, ainsi qu'un lecteur correspondant (LES). Selon le procédé de l'invention, le lecteur fournit un signal de porteuse haute fréquence (s<SUB>T</SUB>) à une antenne d'émission (ANT), des transpondeurs passifs (TRA) dans la zone d'influence de l'antenne (ANT) reçoivent le signal et effectuent une modulation de charge sur le signal reçu, puis le signal HF modulé réinjecté est démodulé dans le lecteur pour évaluer le signal de modulation. A cet effet, un transmetteur de signaux auxiliaire (HSG) génère une porteuse auxiliaire (s<SUB>H</SUB>) décalée d'un angle de phase (f) et synchrone en fréquence par rapport au signal de porteuse (s<SUB>T</SUB>), le signal de porteuse (s<SUB>T</SUB>) et la porteuse auxiliaire (s<SUB>H</SUB>) étant additionnés dans un circuit sommateur (SUM). Le signal de somme résultant (s<SUB>R</SUB>) et le signal de porteuse (s<SUB>T</SUB>) sont tous deux soumis à une démodulation d'amplitude au moyen d'un démodulateur (DEI) et les signaux démodulés (s<SUB>I</SUB>, s<SUB>Q</SUB>) sont traités pour évaluation.
PCT/AT2006/000132 2005-04-07 2006-04-03 Procede pour la demodulation et lecteur pour evaluer des signaux a modulation de charge Ceased WO2006105565A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
AT5912005A AT501055B8 (de) 2005-04-07 2005-04-07 Verfahren zur demodulation und lesegerät zur auswertung lastmodulierter signale
ATA591/2005 2005-04-07

Publications (1)

Publication Number Publication Date
WO2006105565A1 true WO2006105565A1 (fr) 2006-10-12

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AT (1) AT501055B8 (fr)
WO (1) WO2006105565A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8625727B2 (en) 2010-04-02 2014-01-07 Infineon Technologies Ag Demodulator and method for demodulating a carrier signal
US8792846B2 (en) 2010-04-06 2014-07-29 Infineon Technologies Ag Demodulator and method for demodulating a modulated carrier signal

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL1032074C2 (nl) * 2006-06-28 2008-01-02 Nedap Agri B V Zend-/ontvanginrichting voor respondersignalen.

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5056122A (en) * 1989-06-16 1991-10-08 Rockwell International Corporation Phase-shift keyed demodulation apparatus
WO1996018969A1 (fr) * 1994-12-16 1996-06-20 Siemens Aktiengesellschaft Systeme de transmission de donnees sans contact
WO2002023465A2 (fr) * 2000-09-13 2002-03-21 Em Microelectronic-Marin S.A. Synchronisation de la temporisation d'echantillons dans un recepteur rfid
US6531957B1 (en) * 1996-11-29 2003-03-11 X-Cyte, Inc. Dual mode transmitter-receiver and decoder for RF transponder tags

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2855808B1 (de) * 1978-12-22 1980-06-12 Siemens Ag Homodyn-UEbertragungssystem mit Zweiseitenband-Reflexionsfaktor-Modulator im Antwortgeraet
JPS6352082A (ja) * 1986-08-21 1988-03-05 Sharp Corp 移動物体識別装置

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5056122A (en) * 1989-06-16 1991-10-08 Rockwell International Corporation Phase-shift keyed demodulation apparatus
WO1996018969A1 (fr) * 1994-12-16 1996-06-20 Siemens Aktiengesellschaft Systeme de transmission de donnees sans contact
US6531957B1 (en) * 1996-11-29 2003-03-11 X-Cyte, Inc. Dual mode transmitter-receiver and decoder for RF transponder tags
WO2002023465A2 (fr) * 2000-09-13 2002-03-21 Em Microelectronic-Marin S.A. Synchronisation de la temporisation d'echantillons dans un recepteur rfid

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8625727B2 (en) 2010-04-02 2014-01-07 Infineon Technologies Ag Demodulator and method for demodulating a carrier signal
US8792846B2 (en) 2010-04-06 2014-07-29 Infineon Technologies Ag Demodulator and method for demodulating a modulated carrier signal

Also Published As

Publication number Publication date
AT501055A4 (de) 2006-06-15
AT501055B1 (de) 2006-06-15
AT501055B8 (de) 2007-02-15

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