CN101540072A - Reducing false wake-up in a low frequency transponder - Google Patents
Reducing false wake-up in a low frequency transponder Download PDFInfo
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- CN101540072A CN101540072A CNA2009101293494A CN200910129349A CN101540072A CN 101540072 A CN101540072 A CN 101540072A CN A2009101293494 A CNA2009101293494 A CN A2009101293494A CN 200910129349 A CN200910129349 A CN 200910129349A CN 101540072 A CN101540072 A CN 101540072A
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Abstract
A bidirectional remote keyless entry (RKE) transponder comprises an analog front-end (AFE) having a programmable wake-up filter that predefines the waveform timing of the desired input signal, minimum modulation depth requirement of input signal, and independently controllable channel gain reduction of each of its three channels, X, Y, and Z. The wake-up filter parameters are the length of high and low durations of wake-up pulses that may be programmed in a configuration register. The wake-up filter allows the AFE to output demodulated data if the input signal meets its wake-up filter requirement, but does not output the demodulated data otherwise. The AFE output pin is typically connected to an external device for control, such as a microcontroller (MCU). The external device typically stays in low current sleep (or standby) mode when the AFE has no output and switches to high current wake-up (or active) mode when the AFE has output. Therefore, in order to keep the external control device in the low current sleep mode when there is no desired input signal, it is necessary to keep no output at the AFE output pin. This can be achieved by controlling the wake-up filter parameters, minimum modulation depth requirement of input signal, and channel gains of the AFE device. These features can reduce false-wake up of the bidirectional RKE transponder due to undesired input signals such as noise signals.
Description
Female case application number of the application is 200580016443.9, and the applying date is on April 14th, 2005, and denomination of invention is " reducing the false wake-up in the low frequency transponder ".
Technical field
The present invention relates to inductive coupling magnetic field transmission and detection system by and large, and for example remote keyless enters (RKE) and passive type does not have key and enter (PKE) system, and more specifically relates to a kind of Apparatus and method for that is used for reducing the false wake-up of this kind system.
Background technology
In recent years, remote keyless enters the use of (RKE) system in automobile and Secure Application significantly increases.Traditional remote keyless enters (RKE) system and is made up of a RKE transmitter and a base station.Described RKE transmitter has activator button.When pressing an activator button, described RKE transmitter just transfers to described base station with the rf data of correspondence.If described base station receives described data and the data that received effectively then implement suitable operation, for example unlocking/locking closes car door or boot.In traditional RKE system, data transfer to the base station from the RKE transmitter, rather than from base station transmits to transmitter.This so-called one-way communication.
Can make much advanced RKE system by using a kind of two-way communication.Described bidirectional remote keyless access system is made up of a transponder and a base station.Described transponder and base station can communicate under the situation of not using man-machine interface pushbutton voluntarily.If described base station to described transponder send an order and described order effectively described transponder can correspondingly respond to described base station.By utilizing described two-way communication, but people need not to press any button just his/her car door of remote de-locking/locking or boot.Therefore, now can be fully without hand enter room or automobile.
Described two-way communication RKE system is made up of base station and transponder.Described base station can send and receive the low frequency command and can receive the VHF/UHF/ microwave signal.Described transponder can detect low frequency (LF) data and also pass through low frequency or VHF/UHF/ microwave to described base station transmits data.In application, described two-way transponder can optionally have activator button, closes car door, boot or the like but also can be used for (for example) unlocking/locking under the situation of no any activator button.
For can do not exist the transponder operated under the man-machine interface situation reliably without for the manual manipulation, described transponder must enough make decisions intelligently correctly to detect input signal and suitably to manage its operate power with extending battery life.Notion in the application's case has been set forth the transponder dynamic-configuration, its can be during using at any time the feature set to transponder be configured, in without the operating environment of hand, to communicate with aptitude manner and described base station voluntarily.
Referring to Fig. 1, describe a kind of prior art passive type remote keyless among the figure and enter (RKE) system.RKE system that these are wireless is made of a base station 102 (it generally is arranged in the vehicle or in safety entrance is used in automobile is used and is arranged in dwelling house or the office) and RKE transponder 104 (for example key chain) one or more and that base station 102 communicates usually.Base station 102 can comprise a radio-frequency transmitter 106, antenna 110 and (optionally) one low frequency transmitter/reader 108 and associated antennas 112.Transponder 104 can comprise that a radio frequency sending set 122, is coupled to the scrambler 124 of transmitter 122, antenna 118 and (optionally) low frequency transponder 126 and associated antennas 120.Transmitter 122 can communicate with receiver 106 by use very high frequency(VHF) (VHF) or ultrahigh frequency (UHF) radio signal 114 in about 100 meters farthest distance, with a vehicle (not shown) that comprises base station 102 is positioned, locking and separate the warning that locks door, set in the vehicle, or the like.Scrambler 124 can be used for only the action required of designated vehicle being encrypted.Optionally, low frequency transponder 126 be used in one be coupled between coil 112 and 120 116 inherences, magnetic field closely (for example 1.5 meters or following) locate without hand ground locking and release one vehicle or buildings the door.
This type of RKE system is easy to occur false wake-up, battery life is short, working range depends on very much the key chain (not shown) orientation and unreliable.Therefore, need make the mistake of described RKE transponder circuits " wake " number of times up and remain on Min..This is to realize by using the low frequency time-varying magnetic field that the inquiry scope of described base station is limited to described RKE transponder.The flux density in described magnetic field is called " field intensity " and is the sensed object of described magnetic field sensor.It (is 1/d that field intensity reduces with cube form apart from the distance in described source
3).Therefore, effective inquiry scope in magnetic field reduces rapidly.Like this, the RKE transponder is waken up always.Thus, described RKE transponder will be only just be waken up very near correct vehicle the time.Be called " read range " for waking the required proximity distance of RKE transponder up.From described RKE transponder to the VHF of described base station interrogator or UHF response transmission then a much bigger distance and under a lower transmission power level effectively.
When coil that magnetic flux line cutting one is made by lead, can produce electric current, promptly about the electric current in the electric conductor that is subjected to the magnetic fluxes cutting, referring to Maxwell equation (Maxwell ' s Equations).Therefore, detected magnetic flux density will be directly proportional with current amount flowing in the pick-up loop.
Yet under close-coupled or near field noise environment, for example magnetic or electro permanent magnetic noise source can make AFE (analog front end) and the external control device that is associated " wakes up " or keep " waking up " and therefore make power consumption increase and shorten thus battery life.A kind of effective means in order to conserve battery power is with the electronic circuit of RKE device and the unwanted any circuit shutoff that is associated of institute when detecting the electromagnetism RF signal (inquiry question and answer) that whether exists from the keyless access system reader, for example disconnects or makes it enter " park mode ".Only when detecting described interrogating signal, just the electronic circuit with the RKE device reconnects to battery supply (waking up).Yet, there is a problem, when influencing, described RKE device will unnecessarily be waken up when described transponder receiver is subjected to noise source (for example electromagnetic radiation (EMR) of sending from frequency for example and the essentially identical TV of described interrogating signal and computer monitor).If described RKE transponder receiver is subjected to continuing noise source influence, then described battery can exhaust in several days.
Therefore, the mistake that need prevent or obviously reduce the RKE transponder " is waken up ".
Summary of the invention
The present invention is used to reduce mistake that a remote keyless enters (RKE) transponder and " wakes up " and then reduce useless power consumption and increase other shortcoming and the deficiency that battery working time overcomes the problems referred to above and prior art by providing a kind of.
In an exemplary embodiment, according to the present invention, one RKE transponder comprises an AFE (analog front end) (AFE), described AFE (analog front end) (AFE) has the plurality of radio channel, for example channel X, Y and Z (also can be contained more or less channel, this still belongs in the scope of the present invention), and its amplification quantity (gain) can be controlled and programmed at each channel.One external control device (for example digital processing unit, microcontroller, microprocessor, digital signal processor, application specific integrated circuit (ASIC), programmable logic array (PLA) and similar device) may command described a plurality of have can cause the RKE transponder by the make an uproar sensitivity of each channel in the channel that produces of false wake-up excessive.
Can use the programmable controllable gain of each channel in the described plurality of channels during the channel status of band noise, to make individual channel insensitive, otherwise described interchannel noise source can make described AFE and external control device keep waking up, also therefore shortens battery working time thereby power consumption is increased.For example, when described RKE transponder (for example key chain) can produce the computing machine of signal pulse or the placement of other noise source near one under the frequency that described RKE transponder is tuned to, the noise source that does not expect to have just can cause the RKE transponder by false wake-up.
Described external control device can be by (the I for example of a serial communication interface for example
2C, CAN, SPI (serial peripheral interface) and similar interface) gain of dynamically disposing each channel in the described plurality of channels.In the described plurality of channels each all can have a sensitivity adjustment control register that is associated of wherein the desired gain of associated channel being programmed by described serial line interface by described external control device.Therefore, described digitial controller is dynamically programmed and is suitable for the gain of each channel in the noise circumstance, to shorten the time of wherein enabling (waking up) described external control device and other power draw circuit.The gain of each channel all can for example reduce respectively-30dB.
Also can use in the described plurality of channels of described AFE each dynamic gain configuration, by the noise signal state on the particular channel being suppressed improve and the communicating by letter of described base station.For example, when a noise source was being disturbed a channel, it may flood described channel and make and can't carry out proper communication on other channel, because the strongest channel signal is followed the tracks of in described RKE transponder automatic gain control (AGC) usually.Described external control device can use a noise alarm function that will illustrate in greater detail in this article to discern this state, thereby allows to carry out desired communication to reduce by the sensitivity of the channel of noise corrupted on other channel.
Described external control device also can be used for dynamically changing the channel sensitivity of described AFE, for example to judge that the RKE key chain is the scope that limits the RKE transponder outside automobile or in the automobile time.
Can use control to improve the balance of plurality of channels described in the RKE transponder to the sensitivity of each channel, so as to compensate between each channel coil change in signal strength and can be in the ghost effect under user's control.
One feature of various embodiments of the present invention is to the differentiation between strong signal and the weak signal, so that described RKE system only just communicates when having a desired signal to noise ratio (S/N ratio) by software control.Wherein exist in the noise circumstance of noise source of a constant level one, may be difficult to realize that good reception communicates.Described noise source can cause the function of power consumption to be waken up but can not correctly communicate.By guaranteeing to have only enough strong signal (for example being enough to activate described AGC) just can wake described RKE system up, will reduce unnecessary power consumption.
Communication from a base station is made up of a string amplitude-modulated signal pulse, and described amplitude-modulated signal pulse will be by scale-of-two (turn-off and the connect) data stream of described external control device decoding to produce one through the demodulation of described RKE device.If the degree of depth of amplitude modulation (intensity of signal carrier when " connection " is poor with noise intensity when signal carrier " shutoffs ") too weak (low), described demodulator circuit possibly can't be distinguished high signal level (" connection ") and low-signal levels (" shutoff ").Depth of modulation becomes conference improves detection sensitivity.Yet, make detection sensitivity have an advantage according to application and signal condition adjustment.Can require control detection sensitivity by minimum modulation depth is set for input signal.Therefore, can carry out according to the intensity of signal to noise ratio (S/N ratio) the decoding of input signal.
According to a concrete exemplary embodiment, can select a specific minimum modulation depth requirement, for example 12%, 25%, 50%, 75% or the like.Thereby input signal must have a depth of modulation greater than selected depth of modulation (signal+noise)/noise) just can detect described input signal (being in the circuit that wakes up in the power modes).Described minimum modulation depth requires to be programmed (stored) in the configuration register, and can programme from the SPI order of described external control device by one at any time again.
A technological merit of the present invention is to eliminate those substantially because of the meeting of hazardous noise power drain and therefore shorten the false wake-up of battery life unnecessarily.Another technological merit is to keep communication on other channel when a channel when unavailable because of harmful noise.A technological merit is to use a noise alarm function to reduce power consumption and keeps communication again.Another technological merit is to distinguish strong signal and weak signal, so that have only strong signal just can wake the circuit of power consumption up.A technological merit is configuration minimum modulation depth requirement before enabling the decoding of input signal again.Another technological merit be to use an external control device to the gain of each channel, activate that required signal intensity and/or minimum modulation depth require be configured into the programming of action attitude and these program parameters be stored in the configuration register.The those skilled in the art should easily know other technological merit herein according to the content that has disclosed.
Description of drawings
Read hereinafter explanation in conjunction with the accompanying drawings and can more fully understand disclosure of the present invention and advantage thereof, in the accompanying drawings:
Fig. 1 is the schematic block diagrams that a prior art remote keyless enters system;
Fig. 2 is the schematic block diagrams that a remote keyless according to the present invention enters the exemplary embodiment of system;
Fig. 3 is a schematic block diagrams of AFE (analog front end) shown in Fig. 2 (AFE);
Fig. 4 is a schematic block diagrams of an exemplary channel that is made of three channels, detecting device, wake-up filter and detuners shown in Fig. 3;
Fig. 5 is a schematic timing diagram of an exemplary wake-up sequence;
Fig. 6 is for waking an exemplary waveform diagrams of timing sequence up shown in Fig. 5;
Fig. 7 is the form that a demonstration exemplary wake-up filter timing parameters is selected;
Fig. 8 is one in order to judge whether a received signal meets the exemplary flow chart that wake-up filter requires;
Fig. 9 is the exemplary state diagram of the operation of a described wake-up filter;
Figure 10 is the schematic signal level diagram that each minimum modulation depth according to the present invention requires example;
Figure 11 one shows the form to the choosing of requiring of minimum modulation depth and the example;
Figure 12 is an exemplary SPI timing diagram;
Figure 13 is the exemplary table of the bit organization of a configurations shown register; And
Figure 14 is the exemplary table to the SPI order of AFE transponder circuits and configuration register thereof.
The present invention can have various modifications and alternative form.In graphic, specific embodiments of the invention have also been elaborated in this article with the way of example demonstration.Yet, should be appreciated that the explanation that each specific embodiment is done herein is not to be intended to the present invention is defined in the particular form that is disclosed.On the contrary, be intended to contain and still belong to claims defined by enclosing spirit of the present invention and all modifications in the scope, substitute and equivalents.
Embodiment
Referring now to graphic,, schematically show the details of each exemplary embodiment of the present invention among the figure.Components identical will be represented by identical numbering during each is graphic, and similar element will be represented by the identical numbering that has a different lower case letter suffix.
Referring to Fig. 2, it illustrates the schematic block diagrams that a remote keyless according to the present invention enters an exemplary embodiment of (RKE) system.Described RKE system (it is generally by numbering 200 expressions) comprising: a base station 202, and it is arranged in the vehicle or in safety entrance is used in automobile is used usually and is arranged in dwelling house or the office; And one or more RKE transponders 204 that communicate with base station 202, for example key chain.Base station 202 can comprise a radio-frequency transmitter 206, antenna 210 and one low frequency transmitter/reader 208 and associated antennas 212.Transponder 204 can comprise a radio frequency sending set 222, antenna 218, a low frequency analog front-end (AFE) 228, low-frequency antenna 220a, 220b and 220c, an and external control device 224 that is coupled to transmitter 222 and AFE 228.
Transmitter 222 can use very high frequency(VHF) (VHF) or ultrahigh frequency (UHF) radio signal 214 to communicate with receiver 206 in about 100 meters farthest distance, with a vehicle (not shown) that comprises base station 202 is positioned, release and locking car door, set warning in the described vehicle, or the like.External control device 224 can be encrypted the data that transfer to described base station.Low frequency AFE 228 be used in closely (for example 1.5 meters or following) in the magnetic field 216 that is coupled between coil 212 and coil 220a, 220b and/or the 220c locate without hand ground locking and release one vehicle or buildings.
RKE transponder 204 is placed in a key chain (not shown) little, that be easy to carry about with one and the analog usually.Can use minimum internal cell power electronics as RKE transponder 204 in using (wake-up states).The turn-on time of RKE transponder 204 (now using the time) necessary (inevitably) is extremely short, otherwise described little internal cell will exhaust very soon.Therefore, in order to preserve battery life, 204 mosts of the time of RKE transponder are in one " park mode ", are waken up when having the enough strong magnetic field interrogating signal of correct wake-up filter pattern or pressing an action button just have only when detecting one.RKE transponder 204 will in being in enough strong magnetic field 216, (be higher than a sensitivity level) and have one with configuration register in the value of being programmed be complementary correct wake-up filter pattern the time be waken up.Then, RKE transponder 204 will only so be waken up and just respond after described base station interrogator receives a correct command code or when the user asks " release " signal (unlock button on the key chain) of a manual startup.
Base station 202 serve as one in magnetic field 216, send one can be by the interrogator of the command signal of RKE transponder 204 identifications.RKE transponder 204 serves as a transponder with two kinds of different modes: (1) RKE transponder 204 is sent to base station 202 by UHF transmitter 222 with its code, or (2) are by carrying out clamp and separate clamp going out LF and replying to the LC aerial voltage.Base station 202 generations one are in the time-varying magnetic field of a certain frequency (for example 125kHz).In the time of in RKE transponder 204 is in an enough strong magnetic field 216 that is produced by base station 202, RKE transponder 204 will respond under it identifies the situation of its code, if and base station 202 receives a correct response (data) from RKE transponder 204, then described goalkeeper's release or implement scheduled operation, for example turn on light, control actuator, or the like.Therefore, RKE transponder 204 is suitable for the time Variable Amplitude magnetic coupling signal that in a magnetic field 216 sensing one is in a certain frequency.Described magnetic coupling signal carries encoded information (amplitude modulation in described magnetic field), and under the situation that described encoded information and RKE transponder 204 desired information are complementary, this can make RKE transponder 204 return with described base station by low frequency (LF) magnetic field 216 or by UHF radio link road direction and communicate.
The flux density in described magnetic field is called " magnetic field intensity " and is the sensed object of magnetic sensor (for example LC resonant antenna).It (is 1/d that field intensity reduces with cube form apart from the distance in described source
3).Therefore, effective inquiry scope in magnetic field reduces rapidly.Like this, the RKE transponder is waken up always.Thus, described RKE transponder will be only just be waken up very near correct vehicle the time.Be called " read range " for waking the required approaching distance of RKE transponder up.From described RKE transponder to the VHF of described base station interrogator or UHF response transmission then a much bigger distance and under a lower transmission power level effectively.
Described read range for the RKE system accept for moving very important and normally will wake up and the limiting factor of distance that described time-varying magnetic field interrogating signal is decoded to described RKE transponder.Expectation has a read range far away as far as possible.Can obtain a farther read range by any one or a plurality of high voltage of most probables that go up to form in described antenna (220a, 110b and/or 220c).Maximum coil voltage is to obtain when base station coil 212 and arbitrary RKE transponder coil 220 are arranged (promptly magnetic coupling therebetween is the strongest) face-to-face.Because the position of RKE transponder 204 may be at random, if therefore transponder 204 has only a coil 220, then making a transponder coil 220 and base station coil 212 aspectant probability is not very high (only optimum magnetic coil orientation).Therefore, each exemplary specific embodiment of the present invention uses three antennas (for example 220a, 220b and 220c) to RKE transponder 204.These three antenna 220a, 220b and 220c can arrange along orthogonal directions (for example X, Y and Z) during the manufacturing of RKE transponder 204.Therefore, at arbitrary given time, it will be bigger that at least one among these three antenna 220a, 220b and the 220c will be roughly be in the probability that one " face-to-face " be orientated with base station coil 212.Thus, the area detection signal of RKE transponder 204 obtains maximization, thereby makes (work) scope that the reads maximization of RKE system 200.
Except that the required minor increment of the read range of RKE key chain 204, the all possible orientation of RKE key chain 204 all must work in this read range, is in arbitrary three-dimensional (X, Y, Z) position because RKE key chain 204 can send coil 212 with respect to the magnetic of interrogator base station 208.In order to realize this 3 d function, X, Y and Z coil 220a, 220b and 220c are coupled respectively to AFE 228 1 it comprise three channels and the associated circuits of electron-amplifier.In these three channels each is all through amplifying and being coupled to a detecting device (Fig. 3) that detects respectively the signal that receives from X, Y and Z antenna 220a, 220b and 220c.
Referring to Fig. 3, a schematic block diagrams of the AFE (analog front end) shown in the depiction 2 (AFE) 228 among the figure.AFE228 comprises three analog input channels and comprises the amplifier that is used for these three channels (for example X, Y, Z).In these three channels each includes that radio frequency amplitude limitation, antenna are tuning, sensitivity control, automatic gain control amplifier and a detecting device.Each channel all has inner tuning capacity, sensitivity control, an input signal strength limiter and an automatic gain control amplifier.The output of each channel is all through the OR computing and be fed in the detuner.The output of described detuner is fed in the wake-up filter, and if data be complementary with the wake-up filter pattern of being programmed, then can obtain at described LFDATA pin place.Described detuner comprises a signal rectifier, a low-pass filter and a peak detctor.
Described detecting device is coupled to a totalizer that is used to make up the output of these three detecting devices.Also comprise a wake-up filter, some configuration registers and one command decoder/controller among the AFE 228.X, Y and Z antenna 220a, 220b and 220c are coupled respectively to LCX, LCY and LCZ input end, and an end of each antenna in these antenna all can be coupled to a shared pin-LCCOM/Vpp pin.
AFE 228 and X, Y and Z antenna 220a, 220b and 220c combine and can be used for three dimensional signal and detect.Typical frequency of operation can be from about 100kHz to 400kHz.AFE 228 also can run on other frequency and be covered by among the present invention.Two-way contactless operation to all three channels also is covered by among the present invention.Can follow the tracks of the strongest signal and/or can carry out the OR combination received signal on X, Y and Z antenna 220a, 220b and 220c.Can provide a serial line interface to come to communicate with external control device 224.Can use inner trimmer to carry out tuning separately among X, Y and Z antenna 220a, 220b and the 220c each.Described wake-up filter can be configurable.Each channel all has the amplifier that himself is used to detect sensitive signal.Each channel all can have optional sensitivity control.Can forbid or enable each channel separately.The configurable minimum modulation depth that each detecting device all can have input signal requires control.The device option can be provided with by some configuration registers and a row parity bit register (for example seven 9 bit registers).These registers can be programmed by SPI (serial protocol interface) order from external control device 224 (Fig. 2).
Be to the signal of each concrete example expressivity embodiment depicted in figure 3 and the explanation of pin output below.Other combination that the those skilled in the art of electronic applications also can adopt signal and pin to export according to this disclosure, this will still belong in spirit of the present invention and the scope.
V
DDT: the AFE cathode power supply connects.
V
SST: AFE ground connection connects.
Outside LC interface pin on the LCX:X direction.This pin allows to carry out two-way communication on a LC resonant circuit.
Outside LC interface pin on the LCY:Y direction.This pin allows to carry out two-way communication on a LC resonant circuit.
Outside LC interface pin on the LCZ:Z direction.This pin allows to carry out two-way communication on a LC resonant circuit.
LCCOM: be used for the common pin that LCX, LCY and LCZ antenna connect.Also be used for test pattern power supply input (Vpp).
LFDATA/CCLK/RSSI/SDIO: this is the many output pins that can be selected by described configuration register.LFDATA provides the combined digital output from these three detuners.When CS was dragged down, described SDI was the input of SPI numeral.When the SPI read functions implemented register data, described SDO is the output of SPI numeral.RSSI is the output of receiver signal strength indicator.
SCLK/ALERT:SCLK is the digital dock input that is used for SPI communication.If this pin is not used for SPI (the CS pin is for high), then the output of ALERT open collector indicates whether to occur a parity error or an ALARM timer expired do not occur.
CS: the channel that is used for SPI communication is selected pin.Described pin input is that the SPI chip select-begins SPI communication when being dragged down by described external control device, and stops SPI communication when raising.
Referring to Fig. 4, describe the schematic block diagrams of an exemplary channel that constitutes by three channels, detecting device, wake-up filter and detuners shown in Fig. 3 among the figure.Be functional description below to specific exemplary embodiment depicted in figure 4.Other combination that the those skilled in the art of electronic applications also can adopt signal and pin to export according to this disclosure, this will still belong in spirit of the present invention and the scope.
The RF limiter: by with attached LC resonant circuit dequeue limit LC pin input voltage.Absolute voltage limit is to allow input voltage to define by the maximum of silicon technology.When input voltage surpasses V
DEDuring _ Q, described limiter begins the dequeue of outside LC antenna, make dequeue gradually grow be no more than the maximum input voltage of pin to guarantee the antenna input voltage, and the acceptable voltage range of restricted internal agc circuit.
Modulation FET: be used for LC pin and LCCOM " short circuit ", so that carry out the LF reply.Described modulation FET is forbidden when receiving at AFE that " clamp connection " SPI when order activated and receiving " clamp shutoffs " SPI order at AFE.
Antenna is tuning: each input channel all has the tunable capacitor that is connected to the 63pF (resolution is 1pF) of LCCOM from the LC pin.Described tunable capacitor can be used for the resonance frequency of outside LC antenna is finely tuned.
Variable attenuator: the applied signal voltage that decay is controlled by the AGC amplifier.The purpose of decay is to regulate the peak signal voltage that enters detuner.
Programmable attenuator: programmable attenuator is controlled by the configuration register sensitivity setting value of channel.Described attenuator can be used for reducing the susceptibility that described channel wakes up best desired signal.
AGC (automatic gain control): AGC controls described variable attenuator and enters peak signal voltage in the detuner with restriction.Can be with combined from the signal level of all three channels, so that AGC is with respect to all three channels of as one man decaying of the channel with peak signal.
FGA (fixed gain amplifier): FGA1 and FGA2 can provide two gain per stages that are about 40dB.
Detecting device: described detector senses is used to wake up the input signal of AFE.The output of described detecting device is switched with digital form under signal(-) carrier frequency.If select detuner output, then carrier detector is waking the back shutoff up.
Detuner: described detuner is made up of the peak detctor that the amplitude-modulated signal of a full wave rectifier, a low-pass filter and a pair of input carries out demodulation.
Wake-up filter: described wake-up filter meets at input signal enables LFDATA output when wake-up sequence requires.
Data amplitude limiter: described data amplitude limiter will be imported with reference voltage and compare.Described reference voltage is from depth of modulation setting value and crest voltage.
Referring now to Fig. 3 and Fig. 4,, AFE 228 can have an inner 32kHz oscillator.Described oscillator can be used for several timers: stand-by timer, alarm timer, pulse width timer-wake-up filter be high and low, and cycle timer-wake-up filter.Described 32kHz oscillator is preferably lower powered, and can comprise one adjustable resistor-capacitor (RC) pierce circuit.The low-power oscillator of other type also can use and be covered by among the present invention.
If before stand-by timer expires, do not have input signal, then can use stand-by timer to make AFE 228 be back to standby mode automatically by sending a warm reset rice.This is called " stand-by overtime " or TINACT.If a spur signal is waken AFE 228 up, then can use described stand-by timer to minimize, and work can not wake up and can draw more high-power external control device 224 like this by making AFE 228 be back to the electric current that the lower standby mode of electric current draws AFE 228 automatically.Resetted: when receiving a low frequency (LC) signal, when the CS pin is low (arbitrary SPI order) or when carrying out a warm reset relevant the stand-by time with timer.The described stand-by time can start from when not detecting the LF signal.When not having the LF signal that had before received in TINACT, the described stand-by time can be caused an AFE 228 warm resets.Described warm reset can make AFE 228 be back to the standby mode of wherein said AGC, detuner, RC oscillator or the like outage.This can make AFE 228 be back to lower standby current mode.
Described alarm timer can be used for notifying external control device 224 described AFE 228 receiving one not satisfying the LF signal that described wake-up filter requires-make AFE 228 and be in one and be higher than in the state that standby current draws.The effect of described alarm timer is to minimize by the electric current that following manner is drawn AFE 228: make external control device 224 can judge whether continued presence one noise source of AFE 228, and " ignoring " the described noise source that takes appropriate measure to, perhaps be the sensitivity that reduces channel, forbid described channel, or the like.If ignore described noise source, then AFE 228 can be back to low standby current draw state.Described alarm timer can reset under following situation: when the CS pin is low (any SPI order), during the appearance warm reset relevant with alarm timer, when wake-up filter is disabled, when the LFDATA pin is activated (signal passes through wake-up filter).Described alarm timer can start from when receiving a LF signal.Described time of fire alarming can cause a low output on the ALERT pin when its wake command that receives a mistake continuously or periodically reaches about 32ms.This is called " it is overtime to report to the police " or TALARM.If described LF signal for periodically and the time that does not comprise signal greater than T
INACT, then stand-by timer overtime will cause a warm reset-can not send the ALERT indication.
Referring to Fig. 5 and 6, Fig. 5 describes an exemplary waveform diagrams of exemplary wake-up timing sequence shown in a schematic timing diagram of an exemplary wake-up sequence and Fig. 6 depiction 5.Described pulse width (cycle in burst length) timer can be used for verifying that received wake-up sequence meets minimum simultaneously and wakes high time (T up
WAKH) and minimum wake low time (T up
WAKL) requirement.Described cycle timer can be used for verifying that received wake-up sequence meets maximum T
WAKThe T requirement.
Described configurable smart wake-up filter can be used for preventing that AFE 228 from waking external control device 224 up because of harmful input signals such as for example noise or wrong base station commands.In case determined the specific sequence of pulses on the LC input/detector circuit, described LFDATA output just is activated and wakes up external control device 224.Described circuit will be compared with a pre-configured pattern through one " header " (or being called the wake-up filter pattern) of restituted signal, and enable the detuner output on the described LFDATA pin when being complementary.For example, describedly wake requirement up and form with the low duration of minimum of roughly zero number percent of described LF signal by minimum high duration of 100%LF signal (input envelope), back.Height and the selection of low duration are further being implied a maximum period of time.The requirement that wakes the high and low duration up be can be depending on therein the data of being stored in the configuration register that can programme by the SPI interface.Fig. 7 one shows the form that the wake-up filter timing parameters of exemplary is selected, and described wake-up filter timing parameters is programmed in the configuration register so that each RKE transponder all will wake up.Described wake-up filter can enable or forbid.If described wake-up filter is disabled, then AFE 228 exports its demodulated all signals.Preferably, enable described wake-up filter so that external device (ED) or micro controller unit 224 can not wake up because of a unexpected input signal.
When described wake-up sequence is carried out timing, described detuner output is compared with predetermined wake up parameter.Wherein:
Measure T from rising edge to the first falling edge of described detuner output
WAKH.The preferable T that is in of pulse width
WAKH≤t≤T
WAKIn the T.
Measure T from falling edge to the first rising edge of detuner output
WAKL.The preferable T that is in of pulse width
WAKL≤t≤T
WAKIn the T.
From rising edge to rising edge (is T
WAKH and T
WAKThe L sum) measures T
WAKT.T
WAKH and T
WAKThe pulse width of L is preferably t≤T
WAKT.
Described configurable smart wake-up filter can reset, thus need a brand-new succession wake the high and low cycle up to enable LFDATA output under the following conditions.
The height that wakes up that is received is not more than the minimum T that is disposed
WAKThe H value.
What received wakes the low minimum T that is disposed that is not more than up
WAKThe L value.
The wake-up sequence that is received surpasses maximum T
WAKThe T value:
T
WAKH+T
WAKL＞T
WAKT; Or T
WAKH＞T
WAKT; Or T
WAKL＞T
WAKT
Receive warm reset SPI order.
If described wave filter is grown (T because of the time that is in high level
WAKH＞T
WAKT) reset, then the high impulse timer can not restart regularly, until detuner output go up occur one low after the high transition till.
Referring to Fig. 8, describe one among the figure and judge whether a received signal meets the exemplary flow chart that described wake-up filter requires.In step 802, described wake-up filter is in the dormant state.Step 804 inspection whether has a LF input signal and when having a LF input signal, if AGC connects, then step 810 is set AGC and now used mode bit.Step 812 set channel X, Y and/the input channel accepting state position of Z.Step 806 checks whether described LF input signal lacks above 16 milliseconds.If then step 808 will be implemented a warm reset and be back to step 804 to continue to check whether have a LF input signal.
In step 806, if the described non-existent time of LF input signal surpasses 16 milliseconds, then step 814 judges whether enable described wake-up filter.If enable described wake-up filter in step 814, then step 816 judges whether described input LF signal meets described wake-up filter requirement.If meet the requirements, then step 818 provides detected output and external control device 224 to be waken up by LFDATA output on the LFDATA pin.If whether step 820 is judged from the data of described LFDATA pin correct and correct, then in step 822, send it back a response by the LF reply or by a UHF radio frequency link.
In step 816, if described input LF signal does not meet described wake-up filter requirement, then step 824 judges whether received incorrect wake-up (or signal) continues above 32 milliseconds.If be no more than, then step 816 repeats to judge whether described input LF signal meets described wake-up filter requirement.In step 824, if received incorrect wake-up continues to surpass 32 milliseconds, then step 826 setting one alarm output and step 816 continue to judge whether described input LF signal meets described wake-up filter requirement.Referring to Fig. 9, describe an exemplary state diagram of described wake-up filter operation among the figure.
Again referring to Fig. 3, AFE 228 can provide independent sensitivity control in described three channels each.Can adjust described sensitivity control by AFE 228 configuration registers are programmed at any time.Sensitivity control can be set in one of them configuration register of each channel, and can provide sensitivity to reduce, and for example reduces to pact-30dB from about 0dB.By one of them configuration register is programmed, each channel all can have the sensitivity control from about 0dB to pact-30dB of himself.
By the configuration register in the analog front-end device (AFE) 228 is programmed, can enable or forbid each channel respectively.If enable described channel, all circuit in the then described channel all become used.If forbid described channel, then all circuit in the channel of being forbidden are stand-by.Therefore, less than output from disabled channel.The battery current of disabled channel draws is less than the channel that is activated.Therefore, if forbid other two channels when enabling a channel, then the operating power consumption of described device is less than when enabling a more than channel.Existence can make described device move or save the condition of unnecessary working current better by forbidding rather than enable a particular channel during operation.Can when powering up at first, enable in described device or under a power-on reset condition, enable all three channels with default mode.Described external device (ED) or micro controller unit 224 can be programmed to AFE 228 configuration registers, to forbid or to enable each channel during operation when needed at any time.
Step-length that can 1pF is tuned to 63pF from about 0pF respectively with each antenna 220.Can be to the additional tuning capacity of parallel connection outside LC antenna circuit.
Automatic gain control (AGC) amplifier can be amplified to one with the applied signal voltage level automatically and can be the level that detuner is accepted.Described AGC can start apace and slowly discharge, thereby makes the AM data position on described AGC tracking carrier signal level rather than the carrier signal.The strongest signal in these three signals on the described antenna of the preferable tracking of described AGC amplifier.When receiving described SPI warm reset order or behind a stand-by timer expiry, disconnect AGC power supply so that the electric current that is drawn minimize.In case power up, the AGC amplifier just needs reach stable a minimum stabilization time (TSTAB) when receiving input signal.
Referring to Figure 10, describe a schematic signal level diagram among the figure according to each depth of modulation example of the present invention.An incoming signal level has been defined in the configurable minimum modulation depth requirement of input signal must will be detected as the minimum percent that data are hanged down the amplitude peak minimizing of state from it.
Described AGC amplifier will be attempted this with a desirable V of peak signal voltage-regulation to that enters the channel in the data amplitude limiter
AGCREG-attempt to be elevated to V when described signal level
AGCREGReduce the gain in described input path when above, and allow being lower than V
AGCREGSignal level approximate amplify fully.
Described data amplitude limiter detects and is higher than V
THRESHSignal level, V wherein
THRESH＜V
AGCREGV
THRESHIn fact require configuration to change with the minimum modulation depth that is disposed.If described minimum modulation depth requires to be configured to 50%, V
THRESH=1/2V
AGCREG, then from being lower than described peak value (V
AGCREG) will to be regarded as data low for 50% to 100% signal level.
Have only amplitude to be enough to make the resulting amplifying signal level that enters in the described data amplitude limiter to meet or surpass V when signal level
AGCREGThe time, AFE 228 could guarantee that described signal meets the minimum modulation depth requirement.Signal level in entering described data amplitude limiter surpasses V
THRESH, but less than V
AGCREGThe time, do not meet described minimum modulation depth requirement.
If set the SSTR position in the configuration register 5 as shown in Figure 13, then the output through demodulation is under an embargo, unless described incoming level is greater than the AGC threshold level-it can be roughly about 15 millivolts peak-to-peak value.This will make only to detect to have the more signal of high s/n ratio, thereby false wake-up is tailed off, and depend on that described minimum modulation depth requires the sensitivity of setting value but can lose.Between sensitivity and signal to noise ratio (S/N ratio), exist compromise.
The present invention can have low current mode.When for example described digital SPI interface sends a sleep command so that AFE228 is placed a ultralow current-mode, AFE 228 is in the low current sleep mode.Except that for keeping the whole circuit the required minimum circuit of register memory and SPI ability all will cut off the power supply, so that the electric current that AFE 228 is drawn minimizes.Any order except that described sleep command or power-on reset all will wake AFE 228 up.When there is not any LF signal in the antenna input end but described device powers up and carries out when receive preparing basically, AFE 228 is in the low current standby mode.Exist a LF signal and internal circuit on a LF antenna input when switching with the data that received, AFE 228 is in the low current mode of operation.
Configuration memory map also can comprise a row parity byte, and wherein each all is that configuration bit to respective column calculates.Parity checking can be odd (or even parity check).The parity check bit of setting/removing constitutes odd number and sets the position, carries out a power-on reset and described config memory when emptying with box lunch, will produce a parity error that has changed and need reload to the described configuration of outside control device 224 indications.But row and row parity checking on the described configuration memory map of AFE 228 continuous reviews.If a parity error, then AFE 228 can make SCLK/ALERT pin step-down (interrupting external control device 224), thus indicate described config memory destroyed/unload and need reprogramming.Parity error can not interrupted the operation of AFE 228, but indicate content in the described configuration register may be destroyed or parity check bit programmed mistakenly.
The antenna input protection can be used for preventing that too high voltage from entering in the antenna input (LCX shown in Figure 3, LCY and LCZ).When input voltage surpasses starting voltage V
DEDuring Q, the RF limiter circuitry at each LC input pin place all begin with resistance mode with attached outside LC antenna dequeue.The ground dequeue more strongly that is directly proportional with the input voltage of rising of described limiter is no more than the maximum silicon input voltage VLC that allows to guarantee described pin, and input signal is limited to one can be the scope that inner AGC amplifier is accepted.
Can antenna 220 dequeues be realized the LF reply so that modulate data on the aerial voltage that described base station/transponder reader (not shown) is responded to by using a modulated Field effect transistor (MOD FET).Described modulating data can be used as " clamp connection ", " clamp shutoff " orders by described digital SPI interface from external control device 224.Described modulation circuit can comprise the low resistive nmos pass transistor that these three LC inputs is connected to LCCOM.Preferably, slowly conducting of described MOD FET (the perhaps slope of 100ns) is to prevent possible high switch current.When described modulation transistor conducting, its low on-resistance (R
M) the LC aerial voltage can damping responded to.Described aerial voltage minimizes and maximization when described MOD FET turn-offs when described MOD FET conducting.Low on-resistance (the R of described MOD FET
M) can form a high depth of modulation.
The power-on reset (not shown) can remain under the reset mode till can obtaining an enough supply voltage.Described power-on reset enough supplies true(-)running at described supply voltage, and (nominal value is V
POR) time discharges.Described configuration register can all empty when carrying out a power-on reset.Because the protection of the capable and row parity checking of described configuration register, therefore described ALERT pin will by drop-down-to the outside control device 224 described configuration register memory clear-up of indication and need to load.
The output of described LFDATA numeral can be configured to transmit detuner output, carrier clock input or receiver signal strength indicator (RSSI) output.When described detuner output is made up of the modulating data position of recovering from amplitude modulation (AM) carrier envelope line, will use detuner output usually.If carrier clock output is selected by described configuration settings value, then can on the LFDATA pin, obtain carrier clock output.Described carrier clock signal can or use the configuration of carrier clock division to slow down to 1/4th by its raw velocity output.Input end quantity and phase difference between signals according to the while received signal are decided, and resulting carrier clock output may not be the neat square wave representation of described carrier signal.If selected carrier wave is exported all the time, in case then the header counter obtains transmitting, just enable described carrier clock output.When the LFDATA digital output end was configured on the detuner input end output signal, this carrier clock representation can be output actual speed (divided by 1) or slows down (divided by 4).If selective reception S meter (RSSI), then described device output one current signal that is directly proportional with described input signal amplitude.
Referring to Figure 12, describe an exemplary SPI timing diagram among the figure.Described SPI interface can utilize three signals: existing with low chip selection (CS), clock (SCK) and serial data (SDIO).Described SPI can be used for writing and the self-configuring register reads and be used for controlling the circuit of AFE 228 to configuration register by external control device 224.
Referring to Figure 13, describe the exemplary table of the bit organization of a configurations shown register among the figure.As shown in the figure, each configuration register all has nine positions, yet, described configuration register can have more than or less than also containing and belong in the scope of the present invention in nine positions.Position 0 in each register can be the row parity of described register.All registers except that register 7 all can be that can read and rewritable.Register 6 can be the row parity bit register, and wherein each in the register 6 all can be the parity check bit of corresponding register by the bit pattern of row layout.Register 7 can be the circuit activity status register of AFE 228, and can be read-only register.For example, status register 7 can indicate which channel cause an output wake up AFE 228, the activity of indication agc circuit, indication described " alarm output is low " be owing to a parity error or owing to noise alarm timer, or the like.
Figure 14 is the exemplary table to the SPI order of AFE transponder circuits and configuration register thereof.
This paper has set forth the present invention according to each specific exemplary embodiment.According to the present invention, can change systematic parameter, normally by the design engineer at the desired regulation and select described systematic parameter and different of should being used for.In addition, also contain: other embodiment that one of ordinary skill in the art can be easily dream up according to described teaching content herein also can belong to by in the scope of the invention that claims defined of enclosing.Can be by the those skilled in the art according to described teaching content herein and difference easy to know but the present invention is revised and put into practice to the mode of equivalence.
Claims (26)
1, a kind of being used for reduces the method that a remote keyless is entered the false wake-up of (RKE) transponder, and described method comprises the steps:
An AFE (analog front end) (AFE) that enters (RKE) transponder by a remote keyless receives an amplitude modulation (AM) signal; And
Judge whether the described AM signal that receives meets a minimum modulation depth requirement, wherein
If the described AM signal that receives meets described minimum modulation depth requirement, then the described AM signal that receives is detected, and
If the described AM signal that receives does not meet described minimum modulation depth requirement, then the described AM signal that receives is not detected.
2, the method for claim 1, wherein said minimum modulation depth requires the depth of modulation more than or equal to 1 12.
3, the method for claim 1, wherein said minimum modulation depth requires the depth of modulation more than or equal to 25 percent.
4, the method for claim 1, wherein said minimum modulation depth requires the depth of modulation more than or equal to 50 percent.
5, the method for claim 1, wherein said minimum modulation depth requires the depth of modulation more than or equal to 75 percent.
6, the method for claim 1, it comprises the steps: that further described minimum modulation depth is required to be stored to a minimum modulation depth to be required in the configuration register.
7, method as claimed in claim 6, it further comprises the steps: to require the described minimum modulation depth in the configuration register to require to programme by an external control device to described minimum modulation depth.
8, method as claimed in claim 7 is wherein implemented to require described minimum modulation depth in the configuration register to require the described step of programming to described minimum modulation depth by a SPI (serial peripheral interface).
9, the method for claim 1, it further comprises the steps: described minimum modulation depth is required dynamically to be programmed in the minimum modulation depth configuration register.
10, method as claimed in claim 9 is wherein implemented described minimum modulation depth is required dynamically to be programmed to described step in the minimum modulation depth configuration register by an external control device.
11, the method for claim 1, it further comprises the steps: in some power consumption part of waking described RKE transponder when described AM signal is decoded up.
12, a kind of remote keyless with false wake-up of minimizing enters (RKE) transponder, and it comprises:
One AFE (analog front end) (AFE); And
One amplitude modulation (AM) depth detection device circuit, it is used to judge whether one meet a minimum modulation depth requirement by the AM signal that described AFE received, if the wherein described AM signal that receives meets described minimum modulation depth requirement, then the described AM signal that receives is detected, if and the described AM signal that receives do not meet described minimum modulation depth requirement, then the described AM signal that receives is not detected.
13, RKE transponder as claimed in claim 12, wherein said minimum modulation depth requires the depth of modulation more than or equal to 1 12.
14, RKE transponder as claimed in claim 12, wherein said minimum modulation depth requires the depth of modulation more than or equal to 25 percent.
15, RKE transponder as claimed in claim 12, wherein said minimum modulation depth requires the depth of modulation more than or equal to 50 percent.
16, RKE transponder as claimed in claim 12, wherein said minimum modulation depth requires the depth of modulation more than or equal to 75 percent.
17, RKE transponder as claimed in claim 12, it comprises that further one is used to store the depth of modulation configuration register that described minimum modulation depth requires.
18, RKE transponder as claimed in claim 17, it further comprises an external control device, wherein said external control device requires described minimum modulation depth to be programmed in the described depth of modulation configuration register.
19, RKE transponder as claimed in claim 12, some power consumption part of wherein said RKE transponder only is being waken up when described AM signal is decoded.
20, RKE transponder as claimed in claim 12, wherein said AFE comprises that further a plurality of input channels and described AM degree of depth circuit judge whether one meet a minimum modulation depth requirement by the AM signal that each received in described a plurality of input channels, if the wherein described AM signal that receives meets described minimum modulation depth requirement, then the described AM signal that receives is detected, if and the described AM signal that receives do not meet described minimum modulation depth requirement, then the described AM signal that receives is not detected.
21, RKE transponder as claimed in claim 20, a yield value of the described gain that can be by programming mode control of each channel is stored in the programmable configuration register in the wherein said plurality of channels.
22, RKE transponder as claimed in claim 20, each channel in the wherein said plurality of channels is all enabled separately or is forbidden according to the corresponding configuration position in the programmable configuration register.
23, RKE transponder as claimed in claim 20, wherein said a plurality of input channels are three channels.
24, RKE transponder as claimed in claim 20, wherein said minimum modulation depth requires to be equally applicable to described a plurality of input channel.
25, RKE transponder as claimed in claim 24, wherein the described minimum modulation depth to described a plurality of input channels requires to be stored in the minimum modulation depth requirement configuration register.
26, RKE transponder as claimed in claim 25, wherein said minimum modulation depth require configuration register dynamically to require to programme with described minimum modulation depth.
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| US56482404P | 2004-04-23 | 2004-04-23 | |
| US60/564,824 | 2004-04-23 | ||
| US11/079,765 | 2005-03-14 |
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| CN 200580016443 Division CN1957380A (en) | 2004-04-23 | 2005-04-14 | Reducing false wake-up in a low frequency transponder |
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| CNA2009101293494A Pending CN101540072A (en) | 2004-04-23 | 2005-04-14 | Reducing false wake-up in a low frequency transponder |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102184445A (en) * | 2011-05-12 | 2011-09-14 | 广州天绎智能科技有限公司 | Electronic tag awakening method and electronic tag |
| CN105556911A (en) * | 2013-09-20 | 2016-05-04 | 密执安州立大学董事会 | Wake-up receiver with automatic interference rejection |
| CN107017991A (en) * | 2011-08-17 | 2017-08-04 | 通用汽车环球科技运作有限责任公司 | Detect the system and method that one or more user-identification devices are present |
| CN109635604A (en) * | 2019-01-17 | 2019-04-16 | 深圳和而泰智能控制股份有限公司 | A kind of near field identification circuit and system |
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| US8203424B2 (en) * | 2009-03-25 | 2012-06-19 | Lear Corporation | Automatic walk-away detection |
| JP5643033B2 (en) * | 2010-09-06 | 2014-12-17 | トヨタ自動車株式会社 | Wireless communication method and wireless communication device |
| CN102056028A (en) * | 2010-12-30 | 2011-05-11 | 大唐微电子技术有限公司 | Method and device for reducing power consumption of digital interphone |
| US9557802B2 (en) | 2013-08-01 | 2017-01-31 | Mediatek Inc. | Method of controlling SDIO device and related SDIO system and SDIO device |
| US10179567B2 (en) * | 2013-12-03 | 2019-01-15 | Huf North America Automotive Parts Manufacturing Corp. | Protocols for remote vehicle access systems |
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2005
- 2005-04-14 CN CN 200580016443 patent/CN1957380A/en active Pending
- 2005-04-14 CN CNA2009101293494A patent/CN101540072A/en active Pending
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102184445A (en) * | 2011-05-12 | 2011-09-14 | 广州天绎智能科技有限公司 | Electronic tag awakening method and electronic tag |
| CN102184445B (en) * | 2011-05-12 | 2013-04-10 | 广州天绎智能科技有限公司 | Electronic tag awakening method and electronic tag |
| CN107017991A (en) * | 2011-08-17 | 2017-08-04 | 通用汽车环球科技运作有限责任公司 | Detect the system and method that one or more user-identification devices are present |
| CN107017991B (en) * | 2011-08-17 | 2020-12-04 | 通用汽车环球科技运作有限责任公司 | System and method for detecting the presence of one or more subscriber identity devices |
| CN105556911A (en) * | 2013-09-20 | 2016-05-04 | 密执安州立大学董事会 | Wake-up receiver with automatic interference rejection |
| CN109635604A (en) * | 2019-01-17 | 2019-04-16 | 深圳和而泰智能控制股份有限公司 | A kind of near field identification circuit and system |
| CN109635604B (en) * | 2019-01-17 | 2023-12-26 | 深圳和而泰智能控制股份有限公司 | Near field identification circuit and system |
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| CN1957380A (en) | 2007-05-02 |
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