WO2002073234A1 - Presence detection - Google Patents

Presence detection Download PDF

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Publication number
WO2002073234A1
WO2002073234A1 PCT/IB2002/000713 IB0200713W WO02073234A1 WO 2002073234 A1 WO2002073234 A1 WO 2002073234A1 IB 0200713 W IB0200713 W IB 0200713W WO 02073234 A1 WO02073234 A1 WO 02073234A1
Authority
WO
WIPO (PCT)
Prior art keywords
signal
received signal
monitored zone
doppler component
interrogation
Prior art date
Application number
PCT/IB2002/000713
Other languages
French (fr)
Inventor
Hendrik Lodewyk Van Eeden
Original Assignee
Ip And Innovation Company Holdings (Proprietary) Limited
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 Ip And Innovation Company Holdings (Proprietary) Limited filed Critical Ip And Innovation Company Holdings (Proprietary) Limited
Publication of WO2002073234A1 publication Critical patent/WO2002073234A1/en

Links

Classifications

    • 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
    • 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
    • G01S13/02—Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
    • G01S13/50—Systems of measurement based on relative movement of target
    • G01S13/52—Discriminating between fixed and moving objects or between objects moving at different speeds
    • G01S13/56—Discriminating between fixed and moving objects or between objects moving at different speeds for presence detection
    • G—PHYSICS
    • G08—SIGNALLING
    • G08G—TRAFFIC CONTROL SYSTEMS
    • G08G1/00—Traffic control systems for road vehicles
    • G08G1/01—Detecting movement of traffic to be counted or controlled
    • G08G1/017—Detecting movement of traffic to be counted or controlled identifying vehicles

Definitions

  • THIS INVENTION relates to presence detection. In particular, it relates to a method of detecting the presence of an object in a monitored zone of an electronic identification system. It also relates to an electronic identification system.
  • the Applicant is aware of electronic identification systems in which transponders or "tags" are activated by an interrogation signal and then transmit reply signals, usually containing identification data, to a receiver, which typically forms part of the interrogator.
  • reply signals usually containing identification data
  • the interrogation signal also acts as an energy beam used to power the transponder. A small part of this energy is reflected back to the interrogator modulated with an ID code (so-called "back scatter” technique).
  • the interrogator is not able to tell whether an object, such as a person or vehicle, that should have a transponder, is present in the interrogating beam or not.
  • an object such as a person or vehicle
  • the body of the object While passing through the interrogating beam, the body of the object also reflects some of the incident energy back to the interrogator. If the object is moving, the frequency of the reflection will be shifted depending on the speed at which the object is moving. This effect is also known as the "Doppler Effect" .
  • the Doppler frequency component in the reflected signal is unwanted in conventional electronic identification systems, and is filtered out (removed) to improve the signal to noise ratio of the incoming data signal.
  • a method of detecting the presence of a moving object in a monitored zone of an electronic identification system in which transponders are activated by a transmitted interrogation signal and then transmit reply signals including illuminating the monitored zone with said interrogation signal or beam; receiving a reflected and/or reply signal from the monitored zone; separating out a Doppler component, if present, from the received signal; if present, investigating the Doppler component; and determining if a moving object is present in the monitored zone depending on the presence or absence of the Doppler component and, if the Doppler component is present, the characteristics of the Doppler component.
  • the interrogation signal is always reflected back. If the reflected signal does not contain a Doppler component of an appropriate frequency and magnitude, an object is present in the monitored zone, but is not moving, or there is no object in the monitored zone. If a reflected signal is received and it contains a Doppler component of an appropriate frequency and magnitude, a moving object is present in the monitored zone. If this reflected signal does not also include a correct or recognized identification code, reflected by a correct or authorized transponder, it can be deduced that the moving object in the monitored zone is not authorized to move through the monitored zone.
  • the method may include mixing the received signal with the transmitted interrogation signal to convert the received signal down to base band, prior to separating out a Doppler component, if present.
  • Separating out a Doppler component may be effected by means of one or more appropriate filters e.g. a low-pass filter.
  • Investigating the Doppler component may include determining if a Doppler frequency of a suitable magnitude and frequency is present. This could be effected by subjecting the Doppler component to a Fast Fourier Transform operation. However, it is to be appreciated that any suitable conventional spectrum analysis technique may be used for the investigation of the Doppler component.
  • the method may include removing noise from known noise sources which may be present in the monitored zone, from the received signal, e.g. a 50 or 60 Hz mains electric power frequency and/or Doppler components reflected from wheels of a vehicle.
  • Removing noise from the received reflected signal may include comparing the received reflected signal with a stored or reference spectrum reflected by and received from a moving object in the monitored zone, and identifying the lowest new frequency component of the received reflected signal exceeding a preselected magnitude as the Doppler component indicating a moving object in the monitored zone. The remainder of the received signal is thus considered to be noise and is ignored or removed.
  • an electronic identification system of the kind in which a transponder is activated by a transmitted interrogation signal to transmit a reply signal
  • the system including interrogation means for interrogating a monitored zone with an interrogation signal, the interrogation means being configured to receive any reflected and/or reply signal from the monitored zone and to determine if the received signal includes a recognized identification code; first separating means for separating the received signal from the interrogation signal; second separating means for separating any data carrying component of the received signal from any Doppler component of the received signal; and signal processing means for investigating any Doppler component of the received signal.
  • the electronic identification system may include a down converter for mixing a received signal with the interrogation signal to convert the received signal down to base band.
  • the interrogation means may be configured to produce a continuous wave interrogation signal.
  • the interrogation means may include a continuous wave source and an amplifier.
  • the continuous wave source is configured to produce an interrogation signal at about 91 5 MHz or about 2.54 GHz.
  • the interrogation means may employ frequency hopping, a spread spectrum, or frequency modulation.
  • the first separating means may be in the form of a circulator. Instead, it may be in the form of a directional coupler. In yet another embodiment of the invention, the first separating means is in the form of an antenna for receiving the reflected signal and which is separate from an antenna for transmitting the interrogation signal.
  • the second separating means may include a band-pass filter and/or a high-pass filter for separating out any data carrying component. It is however to be appreciated that the filter or filters used will depend on the way the interrogation beam is expected to be modulated and encoded by a correct or authorized transponder in the monitored zone.
  • the second separating means may also include a low-pass filter for separating out any Doppler component.
  • the signal processing means may be in the form of a digital signal processor.
  • the signal processing means may include spectrum storage means for storing a received signal spectrum, for later comparison with a new received signal.
  • reference numeral 1 0 generally indicates an electronic identification system in accordance with the invention.
  • the electronic identification system 1 0 includes interrogation means comprising a continuous wave source 1 2, an amplifier 14, an antenna 1 6 and a comparator 1 7.
  • the electronic identification system 1 0 further includes first separating means in the form of a directional coupler 1 8, a down converter 20, second separating means in the form of a low pass filter 22 and a high pass filter 24, and a digital signal processor 26.
  • the electronic identification system 1 0 is capable of detecting the presence of a moving vehicle in a monitored zone of the interrogator, e.g. in order to determine whether a vehicle is passing through the toll gate of an automated tolling system without an authorised or correct transponder.
  • the continuous wave source 1 2 produces a continuous wave energy beam typically at about 91 5 MHz or about 2.54 GHz.
  • the continuous wave energy beam is amplified by the amplifier 1 4 and beamed or transmitted into the monitored zone, as indicated by reference numeral 28.
  • a vehicle 30 which includes a transponder 32 is shown present and moving through the monitored zone 30.
  • the transponder 32 receives the incident energy from the beam 28, rectifies it and powers up.
  • the transponder 32 then modulates the reflectivity of its antenna with its own identification code to reflect a very small modulated signal back to the interrogation means.
  • the body of the vehicle 30 reflects a much larger signal back to the interrogation means. If the vehicle 30 is stationary, the reflected signal is at the same frequency as the energy beam 28. However, if the vehicle 30 is moving, the reflected signal contains a Doppler frequency component. For example, if the vehicle is moving at about 1 0 meters per second through the monitored zone, and the energy beam 28 is at a frequency of about 91 5 MHz, the Doppler component will be about 30 Hz.
  • the reflected signals from the transponder 32 and the vehicle 30 are received by the antenna 1 6 and separated from the transmitted signal by means of the directional coupler 1 8.
  • the received signals are then mixed with the transmitted signal by means of the down converter 20 to convert the received signals down to base band.
  • a data or identification code component of the received signal is separated out by means of the high-pass filter 24.
  • a Doppler component of the received signal is separated out by means of the low-pass filter 22.
  • the separated out Doppler component is sent to a digital signal processor which uses a Fast Fourier Transform operation to investigate if a Doppler component of a suitable magnitude and frequency is present, and then produces an output signal 32 indicating whether or not a moving vehicle 30 is present in the monitored zone.
  • the data or identification code component, if any, of the reflected signal is send to the comparator 1 7, which determines if the code is a recognized or authorized code and, in response thereto, provides an output signal 34 in this regard.
  • the output signals 32, 34 can be used to take any desired action, depending on the contents or characteristics of the output signals 32, 34.
  • the electronic identification system 10 is intended to work with passive radio frequency identification transponders (RF or inductively coupled) carried by vehicles and activated by a continuous wave signal received from the interrogation means.
  • RF radio frequency identification
  • the invention is also applicable to other systems, e.g. systems using active or passive identification tags or transponders, in which the transponders are triggered to transmit their identification codes by means of some form of interrogation or activation signal.

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  • Engineering & Computer Science (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Radar Systems Or Details Thereof (AREA)

Abstract

The invention provides a method of detecting the presence of a moving object (30) in a monitored zone (28) of an electronic identification system in which transponders (32) are activated by a transmitted interrogation signal and then transmit reply signals. The method includes illuminating the monitored zone (28) with said interrogation signal or beam, receiving a reflected and/or reply signal from the monitored zone (28), and separating out a Doppler component, if present, from the received signal. The Doppler component, if present, is investigated. The method further includes determining if a moving object (30) is present in the monitored zone (28) depending on the presence or absence of the Doppler component and, if the Doppler component is present, the characteristics of the Doppler component.

Description

PRESENCE DETECTION
THIS INVENTION relates to presence detection. In particular, it relates to a method of detecting the presence of an object in a monitored zone of an electronic identification system. It also relates to an electronic identification system.
The Applicant is aware of electronic identification systems in which transponders or "tags" are activated by an interrogation signal and then transmit reply signals, usually containing identification data, to a receiver, which typically forms part of the interrogator. In passive electronic ID systems the interrogation signal also acts as an energy beam used to power the transponder. A small part of this energy is reflected back to the interrogator modulated with an ID code (so-called "back scatter" technique).
In general, the interrogator is not able to tell whether an object, such as a person or vehicle, that should have a transponder, is present in the interrogating beam or not. In auto tolling systems, for example, it is important to know whether a vehicle passed through the tollgate (which is typically always open to allow larger traffic volumes to pass through without slowing down).
While passing through the interrogating beam, the body of the object also reflects some of the incident energy back to the interrogator. If the object is moving, the frequency of the reflection will be shifted depending on the speed at which the object is moving. This effect is also known as the "Doppler Effect" . The Doppler frequency component in the reflected signal is unwanted in conventional electronic identification systems, and is filtered out (removed) to improve the signal to noise ratio of the incoming data signal. According to one aspect of the invention, there is provided a method of detecting the presence of a moving object in a monitored zone of an electronic identification system in which transponders are activated by a transmitted interrogation signal and then transmit reply signals, the method including illuminating the monitored zone with said interrogation signal or beam; receiving a reflected and/or reply signal from the monitored zone; separating out a Doppler component, if present, from the received signal; if present, investigating the Doppler component; and determining if a moving object is present in the monitored zone depending on the presence or absence of the Doppler component and, if the Doppler component is present, the characteristics of the Doppler component.
As will be appreciated, at least some of the interrogation signal is always reflected back. If the reflected signal does not contain a Doppler component of an appropriate frequency and magnitude, an object is present in the monitored zone, but is not moving, or there is no object in the monitored zone. If a reflected signal is received and it contains a Doppler component of an appropriate frequency and magnitude, a moving object is present in the monitored zone. If this reflected signal does not also include a correct or recognized identification code, reflected by a correct or authorized transponder, it can be deduced that the moving object in the monitored zone is not authorized to move through the monitored zone.
The method may include mixing the received signal with the transmitted interrogation signal to convert the received signal down to base band, prior to separating out a Doppler component, if present.
Separating out a Doppler component may be effected by means of one or more appropriate filters e.g. a low-pass filter.
Investigating the Doppler component may include determining if a Doppler frequency of a suitable magnitude and frequency is present. This could be effected by subjecting the Doppler component to a Fast Fourier Transform operation. However, it is to be appreciated that any suitable conventional spectrum analysis technique may be used for the investigation of the Doppler component.
The method may include removing noise from known noise sources which may be present in the monitored zone, from the received signal, e.g. a 50 or 60 Hz mains electric power frequency and/or Doppler components reflected from wheels of a vehicle. Removing noise from the received reflected signal may include comparing the received reflected signal with a stored or reference spectrum reflected by and received from a moving object in the monitored zone, and identifying the lowest new frequency component of the received reflected signal exceeding a preselected magnitude as the Doppler component indicating a moving object in the monitored zone. The remainder of the received signal is thus considered to be noise and is ignored or removed.
According to another aspect of the invention, there is provided an electronic identification system of the kind in which a transponder is activated by a transmitted interrogation signal to transmit a reply signal, the system including interrogation means for interrogating a monitored zone with an interrogation signal, the interrogation means being configured to receive any reflected and/or reply signal from the monitored zone and to determine if the received signal includes a recognized identification code; first separating means for separating the received signal from the interrogation signal; second separating means for separating any data carrying component of the received signal from any Doppler component of the received signal; and signal processing means for investigating any Doppler component of the received signal.
The electronic identification system may include a down converter for mixing a received signal with the interrogation signal to convert the received signal down to base band. The interrogation means may be configured to produce a continuous wave interrogation signal. Thus, the interrogation means may include a continuous wave source and an amplifier. Typically, the continuous wave source is configured to produce an interrogation signal at about 91 5 MHz or about 2.54 GHz. Instead, the interrogation means may employ frequency hopping, a spread spectrum, or frequency modulation.
The first separating means may be in the form of a circulator. Instead, it may be in the form of a directional coupler. In yet another embodiment of the invention, the first separating means is in the form of an antenna for receiving the reflected signal and which is separate from an antenna for transmitting the interrogation signal.
The second separating means may include a band-pass filter and/or a high-pass filter for separating out any data carrying component. It is however to be appreciated that the filter or filters used will depend on the way the interrogation beam is expected to be modulated and encoded by a correct or authorized transponder in the monitored zone. The second separating means may also include a low-pass filter for separating out any Doppler component.
The signal processing means may be in the form of a digital signal processor.
The signal processing means may include spectrum storage means for storing a received signal spectrum, for later comparison with a new received signal.
The invention will now be described, by way of example, with reference to the accompanying diagrammatic drawing which shows a block diagram of an electronic identification system in accordance with the invention.
Referring to the drawing, reference numeral 1 0 generally indicates an electronic identification system in accordance with the invention. The electronic identification system 1 0 includes interrogation means comprising a continuous wave source 1 2, an amplifier 14, an antenna 1 6 and a comparator 1 7. The electronic identification system 1 0 further includes first separating means in the form of a directional coupler 1 8, a down converter 20, second separating means in the form of a low pass filter 22 and a high pass filter 24, and a digital signal processor 26.
The electronic identification system 1 0 is capable of detecting the presence of a moving vehicle in a monitored zone of the interrogator, e.g. in order to determine whether a vehicle is passing through the toll gate of an automated tolling system without an authorised or correct transponder.
In use, the continuous wave source 1 2 produces a continuous wave energy beam typically at about 91 5 MHz or about 2.54 GHz. The continuous wave energy beam is amplified by the amplifier 1 4 and beamed or transmitted into the monitored zone, as indicated by reference numeral 28. In the drawing, a vehicle 30 which includes a transponder 32 is shown present and moving through the monitored zone 30. The transponder 32 receives the incident energy from the beam 28, rectifies it and powers up. The transponder 32 then modulates the reflectivity of its antenna with its own identification code to reflect a very small modulated signal back to the interrogation means.
The body of the vehicle 30 reflects a much larger signal back to the interrogation means. If the vehicle 30 is stationary, the reflected signal is at the same frequency as the energy beam 28. However, if the vehicle 30 is moving, the reflected signal contains a Doppler frequency component. For example, if the vehicle is moving at about 1 0 meters per second through the monitored zone, and the energy beam 28 is at a frequency of about 91 5 MHz, the Doppler component will be about 30 Hz.
The reflected signals from the transponder 32 and the vehicle 30 are received by the antenna 1 6 and separated from the transmitted signal by means of the directional coupler 1 8. The received signals are then mixed with the transmitted signal by means of the down converter 20 to convert the received signals down to base band. A data or identification code component of the received signal is separated out by means of the high-pass filter 24. A Doppler component of the received signal is separated out by means of the low-pass filter 22. The separated out Doppler component is sent to a digital signal processor which uses a Fast Fourier Transform operation to investigate if a Doppler component of a suitable magnitude and frequency is present, and then produces an output signal 32 indicating whether or not a moving vehicle 30 is present in the monitored zone. The data or identification code component, if any, of the reflected signal is send to the comparator 1 7, which determines if the code is a recognized or authorized code and, in response thereto, provides an output signal 34 in this regard. As will be appreciated by those skilled in the art, the output signals 32, 34 can be used to take any desired action, depending on the contents or characteristics of the output signals 32, 34.
The electronic identification system 10 is intended to work with passive radio frequency identification transponders (RF or inductively coupled) carried by vehicles and activated by a continuous wave signal received from the interrogation means. However, the invention is also applicable to other systems, e.g. systems using active or passive identification tags or transponders, in which the transponders are triggered to transmit their identification codes by means of some form of interrogation or activation signal.
It is an advantage of the invention, as illustrated, that it provides a method and means for detecting when an object, such as a vehicle, which should be carrying a correct or authorized identification tag or transponder, is passing through a monitored zone without such an identification tag or transponder.

Claims

CLAIMS:
1 . A method of detecting the presence of a moving object in a monitored zone of an electronic identification system in which transponders are activated by a transmitted interrogation signal and then transmit reply signals, the method including illuminating the monitored zone with said interrogation signal or beam; receiving a reflected and/or reply signal from the monitored zone; separating out a Doppler component, if present, from the received signal; if present, investigating the Doppler component; and determining if a moving object is present in the monitored zone depending on the presence or absence of the Doppler component and, if the Doppler component is present, the characteristics of the Doppler component.
2. A method as claimed in claim 1 , which includes mixing the received signal with the transmitted interrogation signal to convert the received signal down to base band, prior to separating out a Doppler component, if present.
3. A method as claimed in claim 1 or claim 2, in which separating out a
Doppler component is effected by means of one or more appropriate filters.
4. A method as claimed in any one of the preceding claims, in which investigating the Doppler component includes determining if a Doppler frequency of a suitable magnitude and frequency is present.
5. A method as claimed in any one of the preceding claims, in which the method includes removing noise from known noise sources which may be present in the monitored zone, from the received signal.
6. A method as claimed in claim 5, in which removing noise from the received signal includes comparing the received signal with a stored or reference spectrum reflected by and received from a moving object in the monitored zone, and identifying the lowest new frequency component of the received signal exceeding a preselected magnitude as the Doppler component indicating a moving object in the monitored zone.
7. An electronic identification system of the kind in which a transponder is activated by a transmitted interrogation signal to transmit a reply signal, the system including interrogation means for interrogating a monitored zone with an interrogation signal, the interrogation means being configured to receive any reflected and/or reply signal from the monitored zone and to determine if the received signal includes a recognized identification code; first separating means for separating the received signal from the interrogation signal; second separating means for separating any data carrying component of the received signal from any Doppler component of the received signal; and signal processing means for investigating any Doppler component of the received signal.
8. An electronic identification system as claimed in claim 7, which includes a down converter for mixing a received signal with the interrogation signal to convert the received signal down to base band.
9. An electronic identification system as claimed in claim 7 or claim 8, in which the signal processing means includes spectrum storage means for storing a received signal spectrum, for later comparison with a new received signal.
1 0. A method of detecting the presence of a moving object in a monitored zone as claimed in claim 1 , substantially as herein described and illustrated.
1 1 . An electronic identification system as claimed in claim 7, substantially as herein described and illustrated.
12. A new method of detecting the presence of a moving object, or a new identification system, substantially as herein described.
PCT/IB2002/000713 2001-03-14 2002-03-12 Presence detection WO2002073234A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ZA2001/2122 2001-03-14
ZA200102122 2001-03-14

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2006006903A1 (en) * 2004-07-09 2006-01-19 Tagmaster Ab A method for reading a transponder for mobile units
WO2008030357A2 (en) * 2006-09-01 2008-03-13 Sensormatic Electronics Corporation Radio frequency identification system with doppler detector
EP1936740A1 (en) * 2006-12-22 2008-06-25 Giesecke & Devrient GmbH Antenna for measuring movement information according to the Doppler principle, transponder, system and method
WO2011129750A1 (en) * 2010-04-12 2011-10-20 Scirocco Ab Rfid system

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4104630A (en) * 1976-06-21 1978-08-01 Chasek Norman E Vehicle identification system, using microwaves
US4389648A (en) * 1979-07-31 1983-06-21 The Marconi Company Limited Doppler radar system
GB2189362A (en) * 1986-04-16 1987-10-21 Gen Electric Co Plc A frequency domain correlation system
US5247307A (en) * 1990-11-09 1993-09-21 Thomson-Csf Process for the recognition of an aerial target from its radar echo
WO1993023833A1 (en) * 1992-05-11 1993-11-25 Saab-Scania Combitech Aktiebolag A device for detecting and information transfer
US5506584A (en) * 1995-02-15 1996-04-09 Northrop Grumman Corporation Radar sensor/processor for intelligent vehicle highway systems
EP0853245A2 (en) * 1996-12-30 1998-07-15 Lucent Technologies Inc. Modulated backscatter sensor system

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4104630A (en) * 1976-06-21 1978-08-01 Chasek Norman E Vehicle identification system, using microwaves
US4389648A (en) * 1979-07-31 1983-06-21 The Marconi Company Limited Doppler radar system
GB2189362A (en) * 1986-04-16 1987-10-21 Gen Electric Co Plc A frequency domain correlation system
US5247307A (en) * 1990-11-09 1993-09-21 Thomson-Csf Process for the recognition of an aerial target from its radar echo
WO1993023833A1 (en) * 1992-05-11 1993-11-25 Saab-Scania Combitech Aktiebolag A device for detecting and information transfer
US5506584A (en) * 1995-02-15 1996-04-09 Northrop Grumman Corporation Radar sensor/processor for intelligent vehicle highway systems
EP0853245A2 (en) * 1996-12-30 1998-07-15 Lucent Technologies Inc. Modulated backscatter sensor system

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
WILLIAMSON F R ET AL: "A coded radar reflector for remote identification of personnel and vehicles", RADAR CONFERENCE, 1993., RECORD OF THE 1993 IEEE NATIONAL LYNNFIELD, MA, USA 20-22 APRIL 1993, NEW YORK, NY, USA,IEEE, US, 20 April 1993 (1993-04-20), pages 186 - 191, XP010067881, ISBN: 0-7803-0934-0 *

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2006006903A1 (en) * 2004-07-09 2006-01-19 Tagmaster Ab A method for reading a transponder for mobile units
WO2008030357A2 (en) * 2006-09-01 2008-03-13 Sensormatic Electronics Corporation Radio frequency identification system with doppler detector
WO2008030357A3 (en) * 2006-09-01 2008-04-24 Sensormatic Electronics Corp Radio frequency identification system with doppler detector
US7609163B2 (en) 2006-09-01 2009-10-27 Sensormatic Electronics Corporation Radio frequency ID Doppler motion detector
JP2010502951A (en) * 2006-09-01 2010-01-28 センサーマティック・エレクトロニクス・コーポレーション ID Doppler movement detector
AU2007293458B2 (en) * 2006-09-01 2011-09-29 Sensormatic Electronics Llc Radio frequency identification system with doppler detector
CN105738874A (en) * 2006-09-01 2016-07-06 泰科消防及安全有限公司 Radio Frequency Id Doppler Motion Detector
EP3339882A1 (en) * 2006-09-01 2018-06-27 Tyco Fire & Security GmbH Radio frequency identification system with doppler detector
EP1936740A1 (en) * 2006-12-22 2008-06-25 Giesecke & Devrient GmbH Antenna for measuring movement information according to the Doppler principle, transponder, system and method
WO2011129750A1 (en) * 2010-04-12 2011-10-20 Scirocco Ab Rfid system

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