+

WO2006126007A1 - Appareil de detection d'identification hf, synchronisation et fonctionnement de celui-ci - Google Patents

Appareil de detection d'identification hf, synchronisation et fonctionnement de celui-ci Download PDF

Info

Publication number
WO2006126007A1
WO2006126007A1 PCT/GB2006/001943 GB2006001943W WO2006126007A1 WO 2006126007 A1 WO2006126007 A1 WO 2006126007A1 GB 2006001943 W GB2006001943 W GB 2006001943W WO 2006126007 A1 WO2006126007 A1 WO 2006126007A1
Authority
WO
WIPO (PCT)
Prior art keywords
synchronisation
phase
rfid
silent
phases
Prior art date
Application number
PCT/GB2006/001943
Other languages
English (en)
Inventor
Mark Tereszczak
George Powell
Original Assignee
Shearwell Data 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 Shearwell Data Limited filed Critical Shearwell Data Limited
Publication of WO2006126007A1 publication Critical patent/WO2006126007A1/fr

Links

Classifications

    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
    • G06K7/00—Methods or arrangements for sensing record carriers, e.g. for reading patterns
    • G06K7/10—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation
    • G06K7/10009—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation sensing by radiation using wavelengths larger than 0.1 mm, e.g. radio-waves or microwaves
    • G06K7/10316—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation sensing by radiation using wavelengths larger than 0.1 mm, e.g. radio-waves or microwaves using at least one antenna particularly designed for interrogating the wireless record carriers
    • G06K7/10356—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation sensing by radiation using wavelengths larger than 0.1 mm, e.g. radio-waves or microwaves using at least one antenna particularly designed for interrogating the wireless record carriers using a plurality of antennas, e.g. configurations including means to resolve interference between the plurality of antennas
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
    • G06K7/00—Methods or arrangements for sensing record carriers, e.g. for reading patterns
    • G06K7/0008—General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer

Definitions

  • This invention relates to radio frequency
  • RFID identification
  • RFID tag are also called RFID transponders. These names 10 . can be used interchangeably.
  • a radio frequency identification tag is a device that stores unique identification information. When exposed to an interrogating electric field e.g. a radio
  • the tag is energised, i.e. it is "powered up", and is arranged to respond by sending the identification information to a reader (which may be incorporated into the interrogator) .
  • a reader which may be incorporated into the interrogator
  • RFID devices and their readers 25 operate at a number of different frequencies and protocols.
  • One example is the low frequency (LF) type RFID devices which are used in the identification of animals.
  • the frequency band of operation is based around 134.2 kHz. It is possible to write over the information 30 stored in some tags; read-only tags, e.g. with non- modifiable code to ensure security, are typically used as standard at the present time.
  • Two transmission protocols are presently used: full duplex (FDX) and half duplex (HDX) . In the FDX protocol, the response from the tag is sent whilst continuously receiving the interrogating RF energy.
  • the reply transmission from the FDX tag occurs at a different frequency from the interrogating energy so that the reader can recognise that a response is being sent.
  • the response from the tag is sent in a window where no interrogating RF field is present, and the reader is listening for a response.
  • the interrogating field pattern for a HDX tag is therefore necessarily intermittent; the periods where the field is present energise the tag, which then waits for a silent period to send its response.
  • a reader can be constructed to interrogate and read both HDX and FDX tags .
  • a stationary reader can be linked to a fixed installation e.g. to identify cattle flowing through a cattle yard.
  • Fig. 1 shows a standard format of a cyclic electric field emitted by a transmitter arranged to energise a RFID tag so that it may be detected.
  • Fig. 1 shows a plurality of cycles 14, each of which has a transmitting phase 10, where an electric field is generated by the transmitter, and a silent phase 12, where no electric field is generated.
  • the standard format shown in Fig. 1 occurs when no transponders are detected by the reader: the transmitting phase 10 lasts for 50ms, and the silent phase lasts for 3ms.
  • FDX transponders may be detected in the transmitting phase 10. Sometimes, all the information from the FDX tag cannot be completely sent within the 50ms period, e.g.
  • the transmitter's control processor is programmed to extend the transmitting phase 10.
  • the phase is extended for long enough to allow the information from the FDX tag to be completely read or to a maximum of 100ms, to avoid a damaged tag from blocking the system. This extension is illustrated in Fig. 3.
  • the presence of a HDX tag in the field can be detected within the 3ms silent phase 12. If a HDX tag is present, the duration of the silent phase is then extended to 20ms to allow the information from the HDX tag to be read. When no HDX tag is detected, the silent phase 12 lasts for only 3ms. This maximises the fraction of time that the field is transmitted, which maximises the time for detecting FDX tags and for energising HDX tags.
  • Fig. 4 shows a cycle where both phases are extended because an FDX tag and a HDX tag are detected.
  • the maximum cycle duration is 120ms because the phase extensions are limited so that the transmitting phase is not longer than 100ms and the silent phase is not longer than 20ms in operation.
  • more than one tag reader will operate in the local vicinity.
  • it is necessary to synchronise generation of the electric fields of each transmitter so that there is some guaranteed silent time, where none of the transmitters generate a field, so that HDX transponders will be detected. Without synchronisation, the transmitting phase of one transmitter may overlap with the silent phase of another transmitter and prevent any listening silence from occurring.
  • Synchronisation may be achieved by instructing all the transmitters simultaneously to produce a cycle (a synchronisation cycle) having a fixed structure
  • the synchronisation cycle is arranged to occur once every predetermined plural number of cycles, e.g. as every tenth cycle .
  • Fig. 2 shows a synchronisation cycle 16 at the tenth cycle of a transmit format shown in Fig. 1.
  • a further reason for including a synchronisation cycle is to permit mobile readers, i.e. readers that are not connected to a local network of transmitters, to read HDX responses.
  • the mobile reader need not communicate with the transmitters to find out what stage of the cycle is occurring; the mobile reader can simply wait for the silent phase of the synchronisation cycle to occur.
  • One way of ensuring a network of stationary transmitting readers operate correctly and efficiently is to distribute a synchronisation signal to each reader via a wired connection.
  • An example of a scheme to synchronise readers is presented in the ISO 11785: 1996(E), known to the skilled person. This relies on all readers in the vicinity being synchronised and at every tenth transmit/receive cycle all readers transmit for a fixed period of 50ms and receive for a fixed period of 20ms as shown in figure 2.
  • the synchronisation signal proposed in ISO 11785: 1996 (E) is a two state (high/low) signal which is generated as output from a ⁇ master' reader and received as input by the remaining 'slave' readers.
  • the signal is usually in the low state.
  • the readers will transmit cycles having the standard format (50ms transmit followed by 3ms silence) .
  • Each reader also counts the number of cycles transmitted, and when that counter reaches ten, the reader transmits for a fixed time of 50ms, and then generates a 20ms high pulse on the synchronisation signal line.
  • the reader that generates this pulse is the master reader. Any high pulse on the synchronisation signal line automatically prevents the slave readers from transmitting. Thus, all the readers will be silent for 20ms at this point.
  • the slave readers reset their cycle counters so that all readers begin counting up following the synchronisation cycle.
  • the pulse or phase extensions to read late FDX and HDX tags also use the synchronisation signal line. For example, when a reader registers a late FDX and determines that it requires a phase extension, it generates a high pulse on the synchronisation signal line within the 50ms transmit phase, thereby becoming master reader and indicating to the slave readers that transmission should continue until the synchronisation signal is brought low again (which happens automatically at the 100ms limit or can be done by the master reader when the FDX tag is validated) .
  • the extension signal on the synchronisation line is not exactly 20ms because this may be interpreted as a synchronisation cycle by slave readers, which will cause them to reset their counters and therefore disturb synchronisation.
  • Figs. 7, 8, 9, 10 show the electric field produced by a transmitter as shown in Figs. 1, 2, 3, 4 and additionally show the output on the synchronisation signal line from a ⁇ master' transmitter.
  • the synchronisation signal line is low because no transponders have been detected and it is not the tenth (i.e. synchronisation) cycle.
  • the synchronisation signal line is high during the fixed 20ms silent phase of the synchronisation cycle. Any ⁇ slave' transmitters present will reset their counters at the end of this 20ms synchronisation signal.
  • Fig. 7 the synchronisation signal line is low because no transponders have been detected and it is not the tenth (i.e. synchronisation) cycle.
  • the synchronisation signal line is high during the fixed 20ms silent phase of the synchronisation cycle. Any ⁇ slave' transmitters present will reset their counters at the end of this 20ms synchronisation signal.
  • a transmitter which has detected a transponder, but has not succeeded in reading the information from that transponder after 48ms of a transmitting phase 10 extends the transmitting phase 10 by setting the synchronisation signal line to high until it has read the transponder, or, as in this case, until it has extended the transmitting phase to a maximum of 100ms.
  • the transmitter is not allowed to extend the transmitting phase by exactly 20ms to avoid confusion with the synchronisation cycle.
  • a transmitter has detected an FDX transponder and so the signal line is high after 48ms of the transmitting phase and lasts for 52ms to extend the transmitting phase to its maximum of 100ms.
  • a transmitter also detects a HDX transponder in the next silent phase. To inform any other transmitters which are present that the silent phase should be extended to 20ms, the transmitter holds the synchronisation signal line high after 2-3ms of the silent phase until the 20ms (extended) silent phase has finished.
  • Tuning may occur either when a transmitting reader initially enters a network (one or more other readers) , or periodically during operation.
  • Tuning the antenna means selecting an internal configuration which provides optimal performance in a particular network, and involves testing each possible configuration (e.g. combinations of capacitors etc) . Whilst this testing is being carried out, the reader may transmit signals that cause other readers on the network to lose synchronisation. For example, one form of tuning requires the reader to transmit a RF signal for a specific period of time. The network may be down during tuning because no silent periods occur. The network may be brought back up again after tuning has finished. If synchronisation is lost, it will take longer to bring the network back up because of the need to resynchronise .
  • the synchronisation scheme described above suggests pulling the synchronisation signal line high whenever a HDX or FDX tag is detected, and to signal the silent phase of the tenth cycle with a high of fixed duration.
  • the extension signal for HDX tags is 17ms, and for FDX tags is up to 50ms (but not 20ms) . The extension signal is not held for 20ms, to ensure that it is not confused with the 20ms synchronisation signal.
  • a slave For a slave to ensure that a signal on the synchronisation line is a synchronisation signal and not a extension signal, it must time it. This means that the slave reader must be configured to check very accurately for a drop on the synchronisation line around 17ms to distinguish between a HDX extension signal and a synchronisation signal. Such checking requires accurate timing. Moreover, slight phase drift between readers during each ten cycle period can make it difficult to ascertain when a pulse on the synchronisation line actually starts, thereby causing further confusion and greater likelihood of error. Previous proposals have tried to avoid this problem by programming extra rules into the synchronisation protocol of the control processor. For example, the variable FDX extension may be forbidden from being a length that will cause an 20ms pulse to appear on the synchronisation signal line. Extra programming of this kind may contribute to a more complex system, more prone to error.
  • the present invention aims to ameliorate at least some of these problems by providing apparatus and methods with a robust synchronisation scheme.
  • One aspect of the present proposals is to allow tuning to occur without disturbing the synchronisation of the readers connected to the network and therefore to minimise the reader downtime.
  • Another aim is to reduce errors in the identification of the synchronisation signal.
  • the present invention therefore proposes various techniques to improve synchronisation of a network of transmitters .
  • the invention provides systems and methods with identifying means for a phase of the generated electric field.
  • the identified phase may be the transmitting phase of the synchronisation cycle.
  • the invention provides apparatus and methods deploying a synchronisation signal for use with a network (or set) of electric field transmitters arranged to emit an electric field cycle which includes a variable-duration transmitting phase, where an electric field is generated by the transmitters for an extendible duration, and a variable-duration silent phase, where no electric field is generated by the transmitters for an extendible duration, the synchronisation signal being arranged to cause the transmitters simultaneously to emit a synchronisation cycle which has a fixed transmitting phase, where an electric field is generated by the transmitters for a fixed duration, and a fixed silent phase, where no electric field is generated by the transmitters for a fixed duration, wherein the synchronisation signal includes a unique marker to indicate the start of the synchronisation cycle.
  • a transmitter new to the network or an existing slave transmitter can recognise a synchronisation cycle immediately. This avoids the need to distinguish a signal indicating a synchronisation cycle from a signal indicating that either the variable transmitting phase or the variable silent phase should be extended.
  • the marker is arranged to indicate the start of the fixed transmitting phase. This gives the transmitter network time to prepare for the simultaneous fixed silent phase. In particular, it allows a transmitter new to the network to know that a synchronisation cycle is occurring, in time for that transmitter to join in e.g. with the fixed silent phase. This is in contrast to previous proposals , where a new transmitter may only know that a synchronisation cycle has occurred after the fixed silent phase has finished.
  • the synchronisation signal is arranged to be constantly supplied at the control processors of the transmitters of the operational set.
  • the signal desirably has a first state and a second state, and the unique marker preferably includes a transition between the first and second states.
  • the signal may be usually maintained in the first state, the marker preferably including a pulse to the second state and back to the first state.
  • the marker may have one or more pulses in a characteristic pattern.
  • the marker is a double pulse.
  • the states may be respectively characterised by low and high impedance detectable by the transmitters.
  • the signal may be pulled low by a master transmitter, and the marker may include a high pulse on the signal line.
  • a transition between the first and second states coincides with the start of the fixed transmitting phase. The duration of the fixed transmitting phase may be timed from this transition.
  • the duration of the fixed transmitting phase may be 50ms.
  • the duration of the fixed silent phase may be 20ms.
  • the duration of the marker is preferably much less, e.g. less than a tenth, preferably less than a twentieth, of the duration of the synchronisation cycle.
  • the marker duration may be less than lms, preferably around 750 ⁇ s.
  • the marker may be a double pulse. Each pulse may have a different duration, e.g. a longer pulse followed by a shorter pulse or vice versa.
  • the separation between the pulses is preferably very short, e.g. shorter than either pulse.
  • the marker includes a 600 ⁇ s pulse separated from a lOO ⁇ s by a gap of 50 ⁇ s.
  • a marker at the beginning of the silent phase of the synchronisation cycle is also a marker at the beginning of the silent phase of the synchronisation cycle.
  • This marker is preferably different from (e.g. of shorter duration than) a marker signalling the beginning of the transmitting phase of the synchronisation cycle. Its duration may be less than 500 ⁇ s, preferably around 150 ⁇ s.
  • apparatus and methods in the first aspect of the present invention may provide a synchronisation signal for controlling a network of electric field transmitters which are arranged to emit a cyclic electric field, each cycle including a transmitting phase, where an electric field is generated by the transmitters, and a silent phase, where no electric field is generated by the transmitters, wherein the synchronisation signal includes a first unique marker to indicate the start of each transmitting phase and/or a second unique marker to indicate the start of each silent phase.
  • each type of phase is immediately identifiable, which allows a transmitter to join the network more efficiently.
  • the signal is arranged to be constantly supplied to the transmitters, wherein the signal has a first state and a second state, and each marker includes a transition between the first and second states .
  • the signal may usually be maintained in the first state, and each marker may be a pulse to the second state and back to the first state .
  • the first unique marker pulse has a different duration from the second unique marker pulse.
  • it is the duration of the marker pulses which may allow the transmitters to distinguish between them and decide what type of phase is occurring.
  • the duration of each marker pulse is small, e.g. less than a tenth, preferably less than a twentieth, of the duration of the phase that it characterises or indicates.
  • the first marker pulse duration may be less than lms, preferably around 750 ⁇ s.
  • the second marker pulse duration is preferably less than the first marker pulse duration, more preferably less than 500 ⁇ s, most preferably around 150 ⁇ s.
  • the transmitting and silent phases may have variable e.g. extendible duration. Their duration may be varied e.g. extended by delaying the generation of the first or second marker pulse respectively. Extendible duration means that a transmitter output state (emitting or silent, corresponding to the transmitting and silent phases respectively) is maintained for longer than a notional or set minimum or standard duration.
  • the duration may be extended upon receiving an indication e.g. notification or determination that more time is needed in that particular output state e.g. to enable a detected tag to be fully identified.
  • the indication to extend may be the detection of the presence of a tag. Alternatively or additionally, the indication may result from. a determination e.g. calculation that a detected tag will not be fully identified within the notional or set duration.
  • the first and second markers may be used in addition to the synchronisation cycle marker described above.
  • the signal may be further arranged to cause the transmitters simultaneously to emit a synchronisation cycle which has a fixed duration transmitting phase and a fixed duration silent phase, wherein the synchronisation signal includes a third unique marker arranged to indicate the start of the synchronisation cycle.
  • the third marker may have the double pulse structure described above.
  • the first and second markers may be used independently.
  • the first aspect of the invention may be expressed as a synchronisation signal for controlling a network of electric field transmitters which are arranged to emit a cyclic electric field, each cycle including a transmitting phase, where an electric field is generated by the transmitters, and a silent phase, where no electric field is generated by the transmitters, wherein the synchronisation signal includes a unique marker arranged to indicate the start of each transmitting phase.
  • the first aspect may be expressed as a synchronisation signal for controlling a network of electric field transmitters which are arranged to emit a cyclic electric field, each cycle including a transmitting phase, where an electric field is generated by the transmitters, and a silent phase, where no electric field is generated by the transmitters, wherein the synchronisation signal includes a unique marker arranged to indicate the start of each silent phase .
  • the synchronisation signal may be supplied to the network of transmitters via a physical, e.g. wired, connection or via a wireless connection using conventional technology, e.g. infrared communication or the like.
  • the synchronisation signal may be supplied to the network of transmitters by one of the transmitters, more then one of the transmitters or by a separate apparatus.
  • the first aspect may alternatively be expressed as a method of synchronising a network of transmitters arranged to emit an electric field cycle which includes a variable transmitting phase, where an electric field is generated by the transmitters for an extendible duration, and a variable silent phase, where no electric field is generated by the transmitters for an extendible duration, the method including: supplying a synchronisation signal to the transmitters; generating a unique marker on the synchronisation signal to indicate the start of a synchronisation cycle; simultaneously emitting a synchronisation cycle from the transmitters in response to the unique marker on the synchronisation signal, the synchronisation cycle having a fixed transmitting phase, where an electric field is generated by the transmitters for a fixed duration, and a fixed silent phase, where no electric field is generated by the transmitters for a fixed duration.
  • a network of transmitters arranged to emit an electric field cycle which includes a variable transmitting phase, where an electric field is generated by the transmitters for an extendible duration, and a variable silent phase, where no electric field is generated by the transmitters for an extendible duration
  • the network being adapted to receive a synchronisation signal which is arranged to cause the transmitters simultaneously to emit a synchronisation cycle which has a fixed transmitting phase, where an electric field is generated by the transmitters for a fixed duration, and a fixed silent phase, where no electric field is generated by the transmitters for a fixed duration
  • the network is arranged to detect a unique marker on the synchronisation signal, the unique marker being arranged to indicate the start of the synchronisation cycle.
  • a transmitter adapted for connection to or use in an above-described network or apparatus.
  • Synchronisation apparatus programmed to emit a synchronisation signal for controlling a network of transmitters, the synchronisation apparatus including marker generation means for producing a unique marker (e.g. a pulse as described above) on the synchronisation signal, wherein the unique marker is arranged to cause the transmitters simultaneously to emit a synchronisation cycle, e.g. as described above.
  • marker generation means for producing a unique marker (e.g. a pulse as described above) on the synchronisation signal, wherein the unique marker is arranged to cause the transmitters simultaneously to emit a synchronisation cycle, e.g. as described above.
  • a method of detecting RFID devices e.g. carried by animals such as livestock.
  • the method may include energising tags (e.g. RFID tags) carried by the animals by providing a network of electric field transmitters which emit an electric field cycle which includes a variable transmitting phase (e.g. for detecting full duplex [FDX] tags), where an electric field is generated by the transmitters for an extendible duration, and a variable silent phase (e.g. for detecting half duplex
  • the method includes: supplying a synchronisation signal to the transmitters; generating a unique marker on the synchronisation signal to indicate the start of a synchronisation cycle; simultaneously emitting a synchronisation cycle from the transmitters in response to the unique marker on the synchronisation signal, the synchronisation cycle having a fixed transmitting phase, where an electric field is generated by the transmitters for a fixed duration, and a fixed silent phase, where no electric field is generated by the transmitters for a fixed duration.
  • a livestock detection system including a network of electric field transmitters arranged to emit an electric field to energise tags (e.g. RFID tags) carried by the livestock, wherein the network of transmitters is arranged to operate with a synchronisation signal as described above.
  • energise tags e.g. RFID tags
  • the transmitters may also be adapted to detect the presence of the livestock tags.
  • the technique described in the first aspect of the invention can be used to overcome the above-identified problems by generating a marker at the commencement of both transmit and receive periods.
  • all transmitters which are preferably also readers
  • the network know the status of the network within the duration of one phase (e.g. transmitting or silent), i.e. as soon as the transmitters receive a marker on the synchronisation signal line, they know the status of the network. This minimises reader down time due to events such as an auto-tune .
  • the invention provides a network where the transmitters synchronise with each other at every transmitting phase or silent phase (or both) .
  • the transmitters may synchronise at the beginning of each phase. This improves the accuracy of the network without requiring more accurate timing apparatus and reduces the effect of phase drift.
  • a network of transmitters arranged to emit a cyclic electric field, each cycle including a transmitting phase, where an electric field is generated by the transmitters, and a silent phase, where no electric field is generated by the transmitters, wherein each transmitter is connected to a common input arranged to trigger the transmitting and silent phases.
  • the network may include timing apparatus arranged to monitor the duration of the transmitting phase and silent phase of each cycle, the timing apparatus being arranged to begin timing each phase from the common input trigger.
  • the common input supplies a synchronisation signal to trigger the transmitting and silent phases in the transmitters.
  • the synchronisation signal may have markers according to the first aspect of the invention.
  • the synchronisation signal may include a first unique marker arranged to indicate the start of each transmitting phase and a second unique marker arranged to indicate the start of each silent phase, the timing apparatus being arranged to begin timing each phase upon detection of its respective unique marker .
  • Each transmitter may include its own timing apparatus for timing the transmitting and silent phases .
  • the timing apparatus may include separate timers for the transmitting and silent phases .
  • the timers preferably start on detection of the common signal trigger, i.e. they have a common source. This improves synchronicity .
  • a network of transmitters is controlled by a common signal.
  • Each transmitter on the network is arranged to interpret instructions supplied by the common signal to determine how it should act.
  • a network of transmitters arranged to emit a cyclic electric field, each cycle including a transmitting phase, where an electric field is generated by the transmitters, and a silent phase, where no electric field is generated by the transmitters, wherein a common input is supplied to the transmitters, the common input being arranged to provide operation instructions for the transmitters .
  • the operation instructions include one or more of: a transmit instruction to cause the transmitter to emit an electric field; a silence instruction to cause the transmitter to remain silent; a synchronisation instruction to cause the transmitter to emit a synchronisation cycle.
  • the common input is a synchronisation signal.
  • the synchronisation signal may have the form described in the first aspect of the invention.
  • the unigue markers may be used as operating instructions.
  • the signal is constantly supplied to the transmitters and has a first state and a second state, and wherein each instruction includes a transition between the first and second states.
  • each transmitter is arranged to obey each operation instruction until it receives another instruction.
  • This is in contrast to known proposals in that action is required on the synchronisation signal line for any change of state in the transmitters to occur, whereas the known proposals will change state according to a programmed schedule (see e.g. Fig. 1) if there is no action on the synchronisation signal line.
  • the transmitters include a master transmitter arranged to generate the synchronisation signal, and one or more slave transmitters arranged to receive the synchronisation signal.
  • the network is preferably arranged so that any transmitter can be the master transmitter, but only one master transmitter can exist at any point in time. In other words, each transmitter on the network is capable of taking control of the synchronisation signal line.
  • the synchronisation signal can be supplied by a separate apparatus.
  • the duration of the transmitting phase or silent phase of each cycle is extendible by delaying the supply of an operation instruction via the synchronisation signal.
  • each transmitter can communicate to the others by delaying an instruction.
  • this may mean holding the signal line in the first state (e.g. low state) to prevent a instruction (e.g. pulse) from being generated. Only when the master transmitter allows it will an instruction changing the state of the network be generated. This may be used to tell the network to remain silent because of the presence of a HDX tag.
  • the synchronisation signal is arranged to cause the transmitters simultaneously to emit a synchronisation cycle which has a fixed duration transmitting phase and a fixed duration silent phase.
  • the synchronisation signal is arranged to cause the synchronisation cycle to be emitted after a predetermined number of electric field cycles, e.g. as every tenth cycle.
  • the transmitters of all three aspects are arranged also to read (i.e. pick up) signals generated by transponders (e.g. RFID tags) energised by the emitted electric field.
  • the transmitters may read both FDX and HDX response signals.
  • FIG. 1 shows the standard format of a cyclic electric field emitted by a transmitter and has been described above;
  • Fig. 2 shows a synchronisation cycle as the tenth cycle of the electric field shown in Fig. 1, and is also described above;
  • Fig. 3 shows an extended transmitting phase of the electric field shown in Fig. 1, and is also described above;
  • Fig. 4 shows an extended transmitting phase and an extended silent phase of the electric field shown in Fig. 1, and is also described above;
  • Fig. 5 shows the standard format of a cyclic electric field and its associated synchronisation signal line according to an embodiment of the present invention
  • Fig. 6 shows a synchronisation cycle of the electric field shown in Fig. 5 together with its associated synchronisation signal line
  • Fig. 7 shows the electric field emitted by a transmitter as shown in Fig. 1 and also shows the output on the synchronisation signal line from a ⁇ master' transmitter
  • Figs. 8, 9 and 10 supplement the data of Figs. 2, 3 and 4 in the same way.
  • the embodiment described below is implemented on a network of fixed (stationary) tags readers (i.e. electric field transceivers arranged to emit an energising electric field and pick up responses) .
  • the readers can detect both FDX and HDX tags.
  • the readers are interconnected to receive a synchronisation signal.
  • the connection is usually physical, i.e. wired, but wireless arrangements are feasible, e.g. using conventional wireless (e.g. infrared) technology such as Bluetooth® or the like.
  • Each reader has the same synchronisation signal interface; the interface can operate as either an output, i.e. controlling the synchronisation signal line, or input, i.e. responding to signals on the line. In practice, the interface port is pulled to logic high by a high impedance.
  • the synchronisation interface When the synchronisation interface is configured as an output, the reader will determine the ⁇ normal' level of the line as "high” e.g. logic 1. To control the line, the interface causes the line to be pulled “low”, detected as logic 0. Signals (e.g. pulses) are therefore created on the line when no reader is acting to pull the line low, hence it is free to occupy its default "high” position.
  • the synchronisation interface is configured as an output. It is configured to produce the signal line 18 shown in Fig. 5. That is, it pulls line 18 low except for a first pulse 20 lasting 750 ⁇ s which coincides with the start of each transmitting phase 10 and a second pulse 22 lasting 150 ⁇ s which coincides with the start of the silent phase 12. Between the first and second pulses 20, 22 the synchronisation signal line 18 is held low.
  • Extension is allowed to a maximum total duration of 100ms. The extension is achieved by holding the synchronisation line low until the FDX tag is validated or the transmitting phase duration reaches 100ms. Then the line is released for 150 ⁇ s to provide the second pulse 22. In other words, the second pulse 22 is delayed. The transmitter does not become silent until the second pulse 22 is produced.
  • the synchronisation line is held low to extend the silent period (e.g. to its fixed length of 20ms) before releasing the synchronisation line for 750 ⁇ s to provide the first pulse 20.
  • the transmitter does not begin the next transmitting phase until the first pulse 20 is produced.
  • This reader is the master reader, whereas the others are slave readers who listen to the signal line and have no effect on it.
  • the control of the signal line 18 may pass from reader to reader in the course of a number of cycles; a slave reader that requires an extension will become the master reader by taking control of the signal line 18. The previous master reader reverts to being a slave.
  • the network is synchronised so that every tenth cycle is a synchronisation cycle 16 with a fixed format: 50ms transmitting phase followed by 20ms silent phase.
  • the start of the synchronisation cycle 16 is identified by a double pulse 24, which coincides with the start of the tenth transmitting phase.
  • Another pulse 25 (having the same format as the second pulse 22 mentioned above) is produced at the start of the fixed silent period, i.e. exactly 50ms after the start of the double pulse 24.
  • Each reader has a cycle counter running to detect where to insert the synchronisation cycle 16 in the correct position. That is, each reader counts from the previous double pulse 24. When the counter reaches ten, that reader attempts to generate the double pulse. Detection of another double pulse in the meantime will reset the counters of the other readers, thereby synchronising the network.
  • the format of the double pulse 24 is an initial pulse 26 lasting 600 ⁇ s followed by a gap 28 lasting 50 ⁇ s and then a final pulse 30 lasting lOO ⁇ s.
  • the double pulse 24 lasts the same length of time as the first pulse 20, i.e. 750 ⁇ s.
  • a reader joining the existing network typically needs to tune before it can operate; the tuning procedure is described below. However, if the new reader is already tuned, it may obey the following joining procedure : 1. It initially sets its synchronisation interface as an input, i.e. it listens for pulses on the signal line 18; then
  • the new reader If it detects that the signal line remains high for a predetermined period (i.e. it detects no markers), the new reader assumes no other reader is connected and therefore takes control of the synchronisation signal line (by pulling it low as described above) ; or
  • the reader can synchronise with the existing network - e.g. on detecting a 750 ⁇ s pulse, the reader knows that a transmitting phase is occurring, so it may begin transmitting; on detecting a 150 ⁇ s pulse, the reader knows that a silent phase is occurring, so it will keep silent until a transmit pulse occurs; 5. On detecting its first 750 ⁇ s pulse, the reader resets its ten cycle counter, and starts counting cycles - it will attempt to produce the double pulse if it reaches ten; 6. On detecting a double pulse 24 indicating the tenth cycle, the new reader resets its ten cycle counter thereby synchronising to the existing network.
  • the cycle counters operate by counting the number of completed cycles, i.e. transmitting phase followed by silent phase.
  • the length of each phase is immaterial as far as the counters are concerned. Thus, even if a phase extends beyond its notional maximum duration, e.g. due to an auto-tune event (see below) , the established synchronisation of the counters will not be disturbed; they will count up regardless of the unusual nature of any phase when the synchronisation signal line provides the expected markers.
  • timers include a silent period timer triggered by the 150 ⁇ s pulse and a transmit period timer triggered by the 750 ⁇ s pulse. These timers time default periods (50ms and 3ms respectively) which are extendible to maxima
  • a new reader will set its silent period timer upon detection of the 150 ⁇ s pulse and its transmit timer upon detection of the 750 ⁇ s pulse. If the new reader then detects a FDX transponder it will configure its synchronisation interface as an output (i.e. take control of the synchronisation signal line 18) and maintain the line low to prevent a 150 ⁇ s pulse from occurring, thereby causing the remaining readers to carry on transmitting so that the FDX tag may be detected.
  • the reader causes the 750 ⁇ s pulse to be produced by releasing the synchronisation signal line 18 to allow it to return to a high.
  • the remaining readers will have set their synchronisation ports as inputs, so will detect the 750 ⁇ s signal, and begin transmitting again.
  • the same procedure is repeated on the detection of a HDX tag except that the silent period timer is used to extend the silent phase 12 to a maximum duration of 20ms. Only a reader detecting the transponder can increase either the silent or transmit phases by becoming the master in the network, whereby the remaining readers obey the status of the synchronisation line.
  • any of the readers can hold the synchronisation low on detection of a transponder.
  • Each reader may detect a transponder at different times during transmit or silent periods . It will be the last reader to complete the transponder interrogation that will allow the synchronisation signal line 18 to return to a high.
  • each reader is timing its own transmit periods and silent periods from the common synchronisation signal pulses thus preventing periods extending beyond 100ms for transmit and 20ms for the listening periods.
  • a new reader joining the network may need to perform an auto-tune.
  • the reader holds the synchronisation line low, thereby maintaining the network in the current phase (the phase taking place when the auto-tune began) until the auto-tune is completed. This occurs because the transmitters only change phase when a marker is detected on the synchronisation line. If no markers are produced, no change of phase occurs .
  • the synchronisation line is released by the tuned reader, which allows the pulse indicating the next phase to be produced on the synchronisation line.
  • Established readers on the network resume the usual cycle sequence immediately after receiving that identifying pulse (e.g.

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • Artificial Intelligence (AREA)
  • Computer Vision & Pattern Recognition (AREA)
  • General Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Electromagnetism (AREA)
  • General Health & Medical Sciences (AREA)
  • Small-Scale Networks (AREA)

Abstract

L'invention décrit un appareil et des procédés destinés à détecter des dispositifs à identification HF (RFID), comme lorsque l'on détecte du bétail. Des émetteurs génèrent des séquences cycliques d'un champ électrique HF à fin de mettre sous tension des dispositifs à identification HF en vue d'une détection. Les séquences cycliques incluent la transmission de phases pour la mise sous tension et des phases de silence destinées à permettre à des dispositifs à identification HF en alternat (HDX) de répondre. Ces phases peuvent être étendues individuellement par le processeur de commande lorsque le système détecte un dispositif à identification HF afin d'allouer le temps nécessaire pour que la lecture soit achevée. Des émetteurs multiples ont leurs phases synchronisées, de telle sorte que les dispositifs en alternat continuent d'être lisibles au moyen d'un signal de synchronisation partagé qui peut - caractériser chaque phase d'émission et/où chaque phase de silence, de telle sorte que plusieurs émetteurs se synchronisent rapidement et/ou - caractériser une séquence d'impulsions de durée fixe, utilisée pour la synchronisation, au niveau de son début plutôt que lors de sa phase de silence.
PCT/GB2006/001943 2005-05-26 2006-05-26 Appareil de detection d'identification hf, synchronisation et fonctionnement de celui-ci WO2006126007A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB0510783.4 2005-05-26
GB0510783A GB0510783D0 (en) 2005-05-26 2005-05-26 Synchronisation signal

Publications (1)

Publication Number Publication Date
WO2006126007A1 true WO2006126007A1 (fr) 2006-11-30

Family

ID=34834698

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB2006/001943 WO2006126007A1 (fr) 2005-05-26 2006-05-26 Appareil de detection d'identification hf, synchronisation et fonctionnement de celui-ci

Country Status (2)

Country Link
GB (1) GB0510783D0 (fr)
WO (1) WO2006126007A1 (fr)

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5646607A (en) * 1990-06-15 1997-07-08 Texas Instruments Incorporated Transponder/interrogator protocol in a multi-interrogator field
US5748137A (en) * 1996-05-08 1998-05-05 Texas Instruments Incorporated Wireless flywheel synchronization method
WO2001009814A1 (fr) * 1999-08-02 2001-02-08 N.V. Nederlandsche Apparatenfabriek Nedap Synchronisation d'un systeme comprenant une pluralite de dispositifs de lecture

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5646607A (en) * 1990-06-15 1997-07-08 Texas Instruments Incorporated Transponder/interrogator protocol in a multi-interrogator field
US5748137A (en) * 1996-05-08 1998-05-05 Texas Instruments Incorporated Wireless flywheel synchronization method
WO2001009814A1 (fr) * 1999-08-02 2001-02-08 N.V. Nederlandsche Apparatenfabriek Nedap Synchronisation d'un systeme comprenant une pluralite de dispositifs de lecture

Also Published As

Publication number Publication date
GB0510783D0 (en) 2005-06-29

Similar Documents

Publication Publication Date Title
CN100557628C (zh) 用于识别设备的方法和装置
US9247634B2 (en) Systems and methods for synchronizing a plurality of RFID interrogators in a theatre of operation
US5028918A (en) Identification transponder circuit
US8542102B2 (en) Method for operating an RFID network
US5218343A (en) Portable field-programmable detection microchip
EP0953181B1 (fr) Systeme de lecture de plusieurs etiquettes
US6992567B2 (en) Electronic label reading system
KR100525317B1 (ko) 개선된 식별 시스템
CN101517599B (zh) 用于集成的读取器和标签的装置和方法
CN100530224C (zh) Rfid询问器及其数据通信方法
WO2007058798A2 (fr) Protocole de communication sans fil pour systeme de capteur medical
CN102971999B (zh) 用于使用精简的通信协议集合的射频识别标签的方法与系统
KR20070072570A (ko) 자동차를 원격제어하여 확인하는 방법과 장치
US10679583B2 (en) Display device having a controllable deep-sleep mode
US7425888B2 (en) Methods for optimizing communications between an RFID reader and a tag population using non-sequential masking
US10555057B2 (en) Wireless sensor system, communication device, sensor tag, and communication method
US20090058614A1 (en) Electronic identification device or transponder fitted with two antennae tuned to different frequencies
EP1527408B1 (fr) Procede d'anticollision permettant de marquer des intervalles temporels
CN106326795A (zh) 一种解决rfid技术信号干扰的方法
CN102087697B (zh) 一种阅读器与无线标签的数据传输方法
US20070001812A1 (en) Systems and methods for optimizing communications between an RFID reader and a tag population using partial binary tree traversal
CN100568259C (zh) 防冲突中的同步
WO2006126007A1 (fr) Appareil de detection d'identification hf, synchronisation et fonctionnement de celui-ci
CN107659341A (zh) 由nfc‑b读取器发现多个nfc‑b设备的方法以及对应的nfc‑b读取器
KR101744191B1 (ko) 경주마 위치 추적 시스템

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application
NENP Non-entry into the national phase

Ref country code: DE

WWW Wipo information: withdrawn in national office

Country of ref document: DE

NENP Non-entry into the national phase

Ref country code: RU

WWW Wipo information: withdrawn in national office

Country of ref document: RU

122 Ep: pct application non-entry in european phase

Ref document number: 06727155

Country of ref document: EP

Kind code of ref document: A1

点击 这是indexloc提供的php浏览器服务，不要输入任何密码和下载