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  • 专利说明
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    • 专利摘要:
    The present invention includes backscatter communication systems, interrogators, methods of communicating in a backscatter system, and backscatter communication methods. According to one aspect of the present invention, a backscatter communication system includes an interrogator including a transmitter configured to output a forward link communication and a receiver configured to receive a return link communication having a carrier signal, the receiver being configured to reduce the amplitude of the carrier signal of the return link communication; and a communication device configured to modulate the carrier signal to communicate the return link communication responsive to reception of the forward link communication.
    公开号:US20010001758A1
    申请号:US09/757,763
    申请日:2001-01-08
    公开日:2001-05-24
    发明作者:Roy Greeff；David Ovard
    申请人:Roy Greeff；Ovard David K.；
    IPC主号:G06K7-0008
    专利说明:
    [0001] The present invention relates to backscatter communication systems, interrogators, methods of communicating in a backscatter system, and backscatter communication methods. [0001] BACKGROUND OF THE INVENTION
    [0002] Electronic identification systems typically comprise two devices which are configured to communicate with one another. Preferred configurations of the electronic identification systems are operable to provide such communications via a wireless medium. [0002]
    [0003] One such configuration is described in U.S. patent application Ser. No. 08/705,043, filed Aug. 29, 1996, assigned to the assignee of the present application, and incorporated herein by reference. This application discloses the use of a radio frequency (RF) communication system including communication devices. The disclosed communication devices include an interrogator and a remote transponder, such as a tag or card. [0003]
    [0004] Such communication systems can be used in various applications such as identification applications. The interrogator is configured to output a polling or interrogation signal which may comprise a radio frequency signal including a predefined code. The remote transponders of such a communication system are operable to transmit an identification signal responsive to receiving an appropriate polling or interrogation signal. [0004]
    [0005] More specifically, the appropriate transponders are configured to recognize the predefined code. The transponders receiving the code subsequently output a particular identification signal which is associated with the transmitting transponder. Following transmission of the polling signal, the interrogator is configured to receive the identification signals enabling detection of the presence of corresponding transponders. [0005]
    [0006] Such communication systems are useable in identification applications such as inventory or other object monitoring. For example, a remote identification device is attached to an object of interest. Responsive to receiving the appropriate polling signal, the identification device is equipped to output an identification signal. Generating the identification signal identifies the presence or location of the identification device and the article or object attached thereto. [0006]
    [0007] Some conventional electronic identification systems utilize backscatter communication techniques. More specifically, the interrogator outputs a polling signal followed by a continuous wave (CW) signal. The remote communication devices are configured to modulate the continuous wave signal in backscatter communication configurations. This modulation typically includes selective reflection of the continuous wave signal. The reflected continuous wave signal includes the reply message from the remote devices which is demodulated by the interrogator. [0007]
    [0008] Certain drawbacks have been identified with the use of backscatter communication techniques. For example, the transmission of the continuous wave signal using the interrogator can desensitize the receiver of the interrogator during reception thereby of reply signals from associated remote devices. In particular, some of the continuous wave signal tends to bleed through to the received reply messages. Such results in degradation of wireless communications. [0008]
    [0009] There exists a need to provide a system which provides improved wireless communications without the drawbacks associated with conventional devices. [0009] SUMMARY OF THE INVENTION
    [0010] The present invention includes backscatter communication systems, interrogators, methods of communicating in a backscatter system, and backscatter communication methods. [0010]
    [0011] One aspect of the present invention provides a method of reducing power within a modulated return link continuous wave signal of a coherent backscatter communication system including an interrogator and at least one remote communication device. Exemplary remote communication devices include remote intelligent communication (RIC) devices and radio frequency identification devices (RFID) of electronic identification systems. [0011]
    [0012] The interrogator preferably comprises a coherent interrogator configured to provide backscatter communications. More specifically, the interrogator is configured to output a forward link communication and a wireless continuous wave signal using a transmitter. The interrogator is also configured to output a local continuous wave signal to a receiver of the interrogator following transmission of the forward link communication. Provision of the local signal enables coherent operation of the interrogator. The interrogator is operable to receive return link communications from at least one remote communication device responsive to transmission of the forward link wireless communication. [0012]
    [0013] In some embodiments, the interrogator includes a receiver operable to reduce the amplitude of a carrier signal of the return link communication. For backscatter communications, the remote communication device is configured to modulate the continuous wave signal providing a carrier component and side band components. The receiver of the interrogator is preferably configured to reduce the amplitude of the carrier component while maintaining the amplitudes of the side band components. [0013]
    [0014] A communication method according to one aspect of the present invention provides reduction of the amplitude of the carrier component of the modulated continuous wave signal. This method includes the steps of matching the amplitude of a local continuous wave signal with an amplitude of a modulated continuous wave signal; adjusting the phase of the local continuous wave signal following the matching; and summing the local continuous wave signal and the modulated continuous wave signal following the adjusting. The adjusting the phase preferably comprises searching for a phase adjustment of the local continuous wave signal which provides maximum reduction of the amplitude of the modulated continuous wave signal at the frequency of the wireless continuous wave signal. [0014] BRIEF DESCRIPTION OF THE DRAWINGS
    [0015] Preferred embodiments of the invention are described below with reference to the following accompanying drawings. [0015]
    [0016] FIG. 1 is a block diagram of an exemplary communication system. [0016]
    [0017] FIG. 2 is a front view of a wireless remote communication device according to one embodiment of the invention. [0017]
    [0018] FIG. 3 is a front view of an employee badge according to another embodiment of the invention. [0018]
    [0019] FIG. 4 is a functional block diagram of a transponder included in the remote communication device of FIG. 2. [0019]
    [0020] FIG. 5 is a functional block diagram of an interrogator of the communication system. [0020]
    [0021] FIG. 6 is a functional block diagram of an RF section of the interrogator. [0021]
    [0022] FIG. 7 is a functional block diagram of an adaptive canceler of the RF section. [0022]
    [0023] FIG. 8 is a schematic diagram of amplitude detectors and an amplitude adjuster according to one embodiment of the adaptive canceler. [0023]
    [0024] FIG. 9 is a graphical illustration of a summed return link communication output from the adaptive canceler. [0024]
    [0025] FIG. 10 is a schematic diagram illustrating one configuration of an amplitude detector and a phase adjuster of the adaptive canceler. [0025]
    [0026] FIG. 11 is a graphical illustration of a received return link communication. [0026]
    [0027] FIG. 12 is a graphical illustration of a summed return link communication. [0027]
    [0028] FIG. 13 is a diagrammatic representation of a forward link communication and a return link communication within the communication system. [0028] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
    [0029] This disclosure of the invention is submitted in furtherance of the constitutional purposes of the U.S. Patent Laws “to promote the progress of science and useful arts” (Article 1, Section 8). [0029]
    [0030] FIG. 1 illustrates a wireless communication system [0030] 10 embodying the invention. Communication system 10 comprises an electronic identification system in the embodiment described herein. Further, the described communication system 10 is configured for backscatter communications as described in detail below. Other communication protocols are utilized in other embodiments.
    [0031] The depicted communication system [0031] 10 includes at least one electronic wireless remote communication device 12 and an interrogator 26. Radio frequency communications can occur intermediate remote communication devices 12 and interrogator 26 for use in identification systems and product monitoring systems as exemplary applications.
    [0032] Devices [0032] 12 include radio frequency identification devices (RFID) or remote intelligent communication (RIC) devices in the embodiments described herein. Exemplary devices 12 are disclosed in U.S. patent application Ser. No. 08/705,043, filed Aug. 29, 1996. Plural wireless remote communication devices 12 typically communicate with interrogator 26 although only one such device 12 is illustrated in FIG. 1.
    [0033] In one embodiment, wireless remote communication device [0033] 12 comprises a wireless identification device such as the MicroStamp (™) integrated circuit available from Micron Communications, Inc., 3176 S. Denver Way, Boise, Id. 83705. Such a remote communication device 12 can be referred to as a tag or card as illustrated and described below.
    [0034] Although multiple communication devices [0034] 12 can be employed in communication system 10, there is typically no communication between multiple devices 12. Instead, the multiple communication devices 12 communicate with interrogator 26. Multiple communication devices 12 can be used in the same field of interrogator 26 (i.e., within the communications range of interrogator 26). Similarly, multiple interrogators 26 can be in proximity to one or more of devices 12.
    [0035] The above described system [0035] 10 is advantageous over prior art devices that utilize magnetic field effect systems because, with system 10, a greater range can be achieved, and more information can be obtained (instead of just identification information). As a result, such a system 10 can be used, for example, to monitor large warehouse inventories having many unique products needing individual discrimination to determine the presence of particular items within a large lot of tagged products.
    [0036] Remote communication device [0036] 12 is configured to interface with interrogator 26 using a wireless medium in one embodiment. More specifically, communications intermediate communication device 12 and interrogator 26 occur via an electromagnetic link, such as an RF link (e.g., at microwave frequencies) in the described embodiment. Interrogator 26 is configured to output forward link wireless communications 27. Further, interrogator 26 is operable to receive reply or return link wireless communications 29 from devices 12 responsive to the outputting of forward link communication 27. In accordance with the above, forward link communications and return link communications comprise wireless signals, such as radio frequency signals, in the described embodiment. Other forms of electromagnetic communication, such as infrared, acoustic, etc. are possible.
    [0037] Interrogator unit [0037] 26 includes a plurality of antennas X1, R1, as well as transmitting and receiving circuitry, similar to that implemented in devices 12. Antenna X1 comprises a transmit antenna and antenna R1 comprises a receive antenna individually connected to interrogator 26.
    [0038] In operation, interrogator [0038] 26 transmits the interrogation command or forward link communication signal 27 via antenna X1. Communication device 12 is operable to receive the incoming forward link signal. Upon receiving signal 27, communication device 12 is operable to respond by communicating the responsive reply or return link communication signal 29. Communications of system 10 are described in greater detail below.
    [0039] In one embodiment, responsive signal [0039] 29 is encoded with information that uniquely identifies, or labels the particular device 12 that is transmitting, so as to identify any object, animal, or person with which communication device 12 is associated.
    [0040] More specifically, remote device [0040] 12 is configured to output an identification signal within reply link communication 29 responsive to receiving forward link wireless communication 27. Interrogator 26 is configured to receive and recognize the identification signal within the return or reply link communication 29. The identification signal can be utilized to identify the particular transmitting communication device 12.
    [0041] Referring to FIG. 2, one embodiment of remote communication device [0041] 12 is illustrated. The depicted communication device 12 includes a transponder 16 having a receiver and a transmitter as described below. Communication device 12 further includes a power source 18 connected to transponder 16 to supply operational power to transponder 16. In the illustrated embodiment, transponder 16 is in the form of an integrated circuit 19. However, in alternative embodiments, all of the circuitry of transponder 16 is not necessarily all included in integrated circuit 19.
    [0042] Power source [0042] 18 is a thin film battery in the illustrated embodiment, however, in alternative embodiments, other forms of power sources can be employed. If the power source 18 is a battery, the battery can take any suitable form. Preferably, the battery type will be selected depending on weight, size, and life requirements for a particular application. In one embodiment, battery 18 is a thin profile button-type cell forming a small, thin energy cell more commonly utilized in watches and small electronic devices requiring a thin profile. A conventional button-type cell has a pair of electrodes, an anode formed by one face and a cathode formed by an opposite face. In an alternative embodiment, the battery comprises a series connected pair of button type cells.
    [0043] Communication device [0043] 12 further includes at least one antenna connected to transponder 16 for wireless transmission and reception. In the illustrated embodiment, communication device 12 includes at least one receive antenna 44 connected to transponder 16 for radio frequency reception by transponder 16, and at least one transmit antenna 46 connected to transponder 16 for radio frequency transmission by transponder 16. The described receive antenna 44 comprises a loop antenna and the transmit antenna 46 comprises a dipole antenna.
    [0044] Communication device [0044] 12 can be included in any appropriate housing or packaging. FIG. 2 shows but one example of a housing in the form of a miniature housing 11 encasing device 12 to define a tag which can be supported by an object (e.g., hung from an object, affixed to an object, etc.).
    [0045] Referring to FIG. 3, an alternative housing is illustrated. FIG. 3 shows a housing in the form of a card [0045] 13. Card 13 preferably comprises plastic or other suitable material. Plastic card 13 houses communication device 12 to define an employee identification badge including the communication device 12. In one embodiment, the front face of card 13 has visual identification features such as an employee photograph or a fingerprint in addition to identifying text.
    [0046] Although two particular types of housings have been disclosed, the communication device [0046] 12 can be included in any appropriate housing. Communication device 12 is preferably of a small size that lends itself to applications employing small housings, such as cards, miniature tags, etc. Larger housings can also be employed. The communication device 12, provided in any appropriate housing, can be supported from or attached to an object in any desired manner.
    [0047] FIG. 4 is a high level circuit schematic of transponder [0047] 16 utilized in the devices of FIGS. 1-3. In the embodiment shown in FIG. 4, transponder 16 is implemented within monolithic integrated circuit 19. In the illustrated embodiment, integrated circuit 19 comprises a single die, having a size of 209×116 mils2, including a receiver 30, transmitter 32, microcontroller or microprocessor 34, a wake up timer and logic circuit 36, a clock recovery and data recovery circuit 38, and a bias voltage and current generator 42. Integrated circuit 19 preferably comprises a small outline integrated circuit (SOIC) package. Receiver 30 and transmitter 32 comprise wireless communication circuitry configured to communicate wireless signals.
    [0048] In one embodiment, communication devices [0048] 12 switch between a “sleep” mode of operation, and higher power modes to conserve energy and extend battery life during periods of time where no interrogation signal 27 is received by devices 12, using the wake up timer and logic circuitry 36.
    [0049] In one embodiment, a spread spectrum processing circuit [0049] 40 is included in transponder 16. In this embodiment, signals transmitted and received by interrogator 26 and signals transmitted and received by communication device 12 are modulated spread spectrum signals. Many modulation techniques minimize required transmission bandwidth. However, the spread spectrum modulation techniques employed in the illustrated embodiment require a transmission bandwidth that is up to several orders of magnitude greater than the minimum required signal bandwidth. Although spread spectrum modulation techniques are bandwidth inefficient in single user applications, they are advantageous where there are multiple users, as is the case with the preferred radio frequency identification communication system 10 of the present invention.
    [0050] The spread spectrum modulation technique of the illustrated embodiment is advantageous because the interrogator signal can be distinguished from other signals (e.g., radar, microwave ovens, etc.) operating at the same frequency. The spread spectrum signals transmitted by communication device [0050] 12 and interrogator 26 are pseudo random and have noise-like properties when compared with the digital command or reply. The illustrated embodiment employs direct sequence spread spectrum (DSSS) modulation.
    [0051] In operation, interrogator [0051] 26 sends out a command that is spread around a certain center frequency (e.g, 2.44 GHz). After the interrogator transmits the command, and is expecting a response, the interrogator switches to a continuous wave (CW) mode for backscatter communications. In the continuous wave mode, interrogator 26 does not transmit any information. Instead, the interrogator just transmits a radio frequency continuous wave signal. In the described embodiment, the continuous wave signal comprises a radio frequency 2.44 GHz carrier signal. In other words, the continuous wave signal transmitted by interrogator 26 is not modulated. After communication device 12 receives the forward link communication from interrogator 26, communication device 12 processes the command.
    [0052] If communication device [0052] 12 is operating in a backscatter mode, device 12 modulates the continuous wave signal providing a modulated continuous wave signal to communicate return link communication 29 responsive to reception of forward communication signal 27. Communication device 12 may modulate the continuous wave signal according to a subcarrier or modulation signal. Modulation by device 12 comprises selective reflection of the continuous wave signal. In particular, device 12 alternately reflects or does not reflect the continuous wave signal from the interrogator to send its reply. For example, in the illustrated embodiment, two halves of a dipole antenna are either shorted together or isolated from each other to send a reply. Alternatively, communication device 12 can communicate in an active mode.
    [0053] The modulated continuous wave signal communicated from device [0053] 12 comprises a carrier component and plural side band components about the carrier component resulting from the modulation. More specifically, the modulated continuous wave signal output from device 12 includes a radio frequency continuous wave signal having a first frequency (2.44 GHz), also referred to as a carrier component, and a subcarrier modulation signal having a different frequency (e.g., 600 kHz) and which provides the side band components. In particular, the side band components are at +/−600 kHz of the carrier component. The carrier and side band components are illustrated in FIG. 11 and FIG. 12.
    [0054] In one embodiment, the clock for transponder [0054] 16 is extracted from the incoming message itself by clock recovery and data recovery circuitry 38. This clock is recovered from the incoming message, and used for timing for microcontroller 34 and all the other clock circuitry on the chip, and also for deriving the transmitter carrier or the subcarrier, depending on whether the transmitter is operating in active mode or backscatter mode.
    [0055] In addition to recovering a clock, the clock recovery and data recovery circuit [0055] 38 also performs data recovery on valid incoming signals. The valid spread spectrum incoming signal is passed through the spread spectrum processing circuit 40, and the spread spectrum processing circuit 40 extracts the actual ones and zeros of data from the incoming signal. More particularly, the spread spectrum processing circuit 40 takes chips from the spread spectrum signal, and reduces individual thirty-one chip sections down to a bit of one or zero, which is passed to microcontroller 34.
    [0056] Microcontroller [0056] 34 includes a serial processor, or I/O facility that receives the bits from spread spectrum processing circuit 40. The microcontroller 34 performs further error correction. More particularly, a modified hamming code is employed, where each eight bits of data is accompanied by five check bits used by the microcontroller 34 for error correction. Microcontroller 34 further includes a memory, and after performing the data correction, microcontroller 34 stores bytes of the data bits in memory. These bytes contain a command sent by the interrogator 26. Microcontroller 34 is configured to respond to the command.
    [0057] For example, interrogator [0057] 26 may send a command requesting that any communication device 12 in the field respond with the device's identification number. Status information can also be returned to interrogator 26 from communication devices 12.
    [0058] Communications from interrogator [0058] 26 (i.e., forward link communications) and devices 12 (i.e., return link communications) have a similar format. Exemplary communications are discussed below with reference to FIG. 13. More particularly, the forward and reply communications individually include a calibration period, preamble, and Barker or start code which are followed by actual data in the described embodiment. The incoming forward link message and outgoing reply preferably also include a check sum or redundancy code so that transponder 16 or interrogator 26 can confirm receipt of the entire message or reply.
    [0059] Communication devices [0059] 12 typically include an identification sequence identifying the particular tag or device 12 sending the reply. Such implements the identification operations of communication system 10.
    [0060] After sending a command, interrogator [0060] 26 sends the unmodulated continuous wave signal. Return link data can be Differential Phase Shift Key (DPSK) modulated onto the continuous wave signal using a square wave subcarrier with a frequency of approximately 600 kHz (e.g., 596.1 kHz in one embodiment). A data 0 corresponds to one phase and data 1 corresponds to another, shifted 180 degrees from the first phase.
    [0061] The subcarrier or modulation signal is used to modulate antenna impedance of transponder [0061] 16 and generate the modulated continuous wave signal. For a simple dipole, a switch between the two halves of the dipole antenna is opened and closed. When the switch is closed, the antenna becomes the electrical equivalent of a single half-wavelength antenna that reflects a portion of the power being transmitted by the interrogator. When the switch is open, the antenna becomes the electrical equivalent of two quarter-wavelength antennas that reflect very little of the power transmitted by the interrogator. In one embodiment, the dipole antenna is a printed microstrip half wavelength dipole antenna.
    [0062] Referring to FIG. 5, one embodiment of interrogator [0062] 26 is illustrated. The depicted interrogator 26 includes a microcontroller 70, a field programmable gate array (FPGA) 72, and RF section 74. In the depicted embodiment, microcontroller 70 comprises a MC68340 microcontroller available from Motorola, Inc. FPGA 72 comprises an XC4028 device available from Xilinx, Inc. Further details of components 70, 72, and 74 are described below.
    [0063] RAM [0063] 76, EPROM 78 and flash memory 80 are coupled with microcontroller 70 in the depicted embodiment. Microcontroller 70 is configured to access an applications program for controlling the interrogator 26 and interpreting responses from devices 12. The processor of microcontroller 70 is configured to control communication operations with remote communication devices 12 during normal modes of operation. The applications program can also include a library of radio frequency identification device applications or functions. These functions effect radio frequency communications between interrogator 26 and communication device 12.
    [0064] RF section [0064] 74 is configured to handle wireless (e.g., radio frequency) communications with remote communication devices 12. DPSK modulation techniques can be utilized for communications intermediate devices 12 and interrogator 26. RF section 74 can include downconversion circuitry for generating in-phase (I) and quadrature (Q) signals which contain the DPSK modulated subcarrier for application to FPGA 72 during return link communications.
    [0065] Plural antennas, including a transmit antenna X[0065] 1 and a receive antenna R1 are coupled with RF section 74 for wireless RF communications. Plural RF transmit (TX) ports and RF receive (RX) ports (not shown) are coupled with RF section 74 in a preferred embodiment. Provision of plural TX ports and RX ports enables interrogator 26 to minimize the effects of multipath when communicating with plural remote communication devices 12.
    [0066] Analog to digital converters [0066] 82, 84 provide received analog RF signals into a digital format for application to FPGA 72. In particular, analog to digital converters 82, 84 are implemented intermediate FPGA 72 and RF section 74 for both in-phase (I) and quadrature (Q) communication lines. An additional connection 85 is provided intermediate FPGA 72 and RF section 74. Digital signals output from FPGA 72 via connection 85 are converted to RF signals by RF section 74. Connection 85 can be utilized to transmit phase lock loop (PLL) information, antenna diversity selection information and other necessary communication information. During forward link communications, FPGA 72 is configured to format communication packets received from microcontroller 70 into a proper format for application to RF section 74 for communication.
    [0067] FPGA [0067] 72 is configured to demodulate return link communications received from remote communication devices 12 via RF section 74. FPGA 72 is configured in the described embodiment to perform I and Q combination operations during receive operations. The described FPGA 74 further includes delay and multiplication circuitry to remove the subcarrier. FPGA 74 can also include bit synchronization circuitry and lock detection circuitry. Data, clock and lock detection signals generated within FPGA 74 are applied to microcontroller 70 for processing in the described embodiment.
    [0068] Microcontroller [0068] 70 is configured to control operations of interrogator 26 including outputting of forward link communications and receiving reply link communications. EPROM 78 is configured to store original code and settings selected for the particular application of communication system 10. Flash memory 80 is configured to receive software code updates which may be forwarded to interrogator 26.
    [0069] RAM device [0069] 76 is configured to store data during operations of communication system 10. Such data can include information regarding communications with associated remote communication devices 12 and status information of interrogator 26 during normal modes of operation.
    [0070] Referring to FIG. 6, an exemplary embodiment of RF circuitry [0070] 74 is illustrated. The depicted RF circuitry 74 includes a transmit path 86 and a receive path 87. In the depicted embodiment, RF section 74 includes a transmitter 90, coupler 91 and power amplifier 92 within transmit data path 86. Receive path 87 includes a receiver 95 comprising processing circuitry 96 and an adaptive canceler 97 in the depicted embodiment.
    [0071] Communication paths [0071] 86, 87 are coupled with respective antennas X1 and R1. Transmit path 86 is additionally coupled with FPGA 72 via connection 85. Receive path 87 is coupled with analog-to-digital converters 82, 84 via the I, and Q connection lines.
    [0072] During communication operations, transmitter [0072] 90 is configured to output a radio frequency wireless forward link communication 27 and a radio frequency wireless continuous wave signal using coupler 91 and antenna X1. Further, transmitter 90 is also configured to output a local continuous wave signal using coupler 91. Transmitter 90 is preferably configured to simultaneously output the wireless continuous wave signal using antenna X1, and the local continuous wave signal using coupler 91. The wireless continuous wave signal transmitted via antenna X1 and the local continuous wave signal provided to receiver 95 via coupler 91 have a common frequency (e.g., 2.44 GHz in the described embodiment).
    [0073] Receiver [0073] 95 is operable to receive the return link communications 29 from at least one remote communication device 12 using antenna R1. As described in detail below, adaptive canceler 97 of receiver 95 is configured to receive the local continuous wave signal from coupler 91. Provision of the local signal provides a coherent backscatter interrogator 26 including a coherent transmitter 90 and receiver 95.
    [0074] As previously described, return link communication [0074] 29 comprises a modulated continuous wave signal in the described embodiment. The modulated signal comprises a carrier signal located at the frequency of the wireless continuous wave signal (e.g., 2.44 GHz), and side bands located at +/−600 kHz about the frequency of the carrier signal. In the described embodiment, receiver 95 is configured to reduce the power or amplitude of the return link communication. More specifically, receiver 95 is configured to reduce the power or amplitude of the carrier signal of the return link communication.
    [0075] In one embodiment, receiver [0075] 95 is operable to reduce the amplitude of the return link communication comprising the modulated continuous wave signal using the local continuous wave signal. More specifically, receiver 95 is configured to reduce the amplitude of the return link communications received by antenna R1 at the common frequency of the continuous wave signals in the described embodiment.
    [0076] As described in detail below, receiver [0076] 95 is configured to receive the local continuous wave signal from coupler 91 and adjust the amplitude and phase of the local continuous wave signal. Such adjustment provides an adjusted continuous wave signal. In particular, the amplitude of the local continuous wave signal is adjusted responsive to the amplitude of the modulated continuous wave signal. Preferably, the amplitude of the local continuous wave signal is adjusted to match the amplitude of the received return link communication. The amplitude of the local continuous wave signal is adjusted before adjustment of the phase of the local continuous wave signal in the described embodiment. Following amplitude and phase adjustment, receiver 95 is configured to sum the adjusted continuous wave signal with the modulated continuous wave signal. Thereafter, the summed return link communication having a reduced amplitude at the frequency of the wireless continuous wave signal is applied to processing circuitry 96.
    [0077] Referring to FIG. 7, one embodiment of adaptive canceler [0077] 97 is illustrated. Adaptive canceler 97 is configured to reduce the amplitude of return link communications 29. More specifically, during backscatter communications, receive path 87 is susceptible to bleed through of the wireless continuous wave signal transmitted via antenna X1. More specifically, the wireless continuous wave signal communicated via transmit antenna X1 can saturate the front end of receiver 95. This leakage can desensitize receiver 95 and reduce the quality of wireless communications of interrogator 26 with remote communication devices 12.
    [0078] Adaptive canceler [0078] 97 utilizes the local continuous wave signal received from transmitter 90 and coupler 91 to reduce the amplitude of the return link communication received by antenna R1 at the frequency of the wireless continuous wave signal transmitted via antenna X1.
    [0079] As previously described, transmitter [0079] 90 is configured to output local and wireless continuous wave signals using coupler 91. Initially, the local continuous wave signal is applied to a variable attenuator 105 within adaptive canceler 97. In the described embodiment, variable attenuator 105 comprises a voltage controlled attenuator. Variable attenuator 105 is configured to adjust the amplitude of the local continuous wave signal responsive to an external control signal discussed below.
    [0080] Variable attenuator [0080] 105 outputs an amplitude adjusted local continuous wave signal. The amplitude adjusted local continuous wave signal is applied to a phase shifter 106. Phase shifter 106 preferably comprises a 360° phase shifter configured to provide an appropriate phase shift of the amplitude adjusted local continuous wave signal. Phase shifter 106 outputs an amplitude and phase adjusted local continuous wave signal which is also referred to as the adjusted continuous wave signal. Phase shifter 106 is controllable via an external control signal described below.
    [0081] The amplitude and phase adjusted local continuous wave signal output from phase shifter [0081] 106 is supplied to a power divider 107. Power divider 107 operates to apply the signal to a detector 108 and coupler 109. Detector 108 is operable to measure the amplitude of the adjusted local signal and apply an output signal to an amplitude adjuster 110.
    [0082] Return link communication [0082] 29 received via antenna R1 is applied to a coupler 114. Coupler 114 applies the received return link communication 29 to coupler 109 and an amplitude detector 115. Detector 115 is configured to measure the amplitude of the received return link communication 29.
    [0083] Referring to FIG. 8, exemplary embodiments of amplitude adjuster [0083] 110 and detectors 108, 115 are illustrated. Detectors 108, 115 individually comprise discrete components including diodes, resistors and capacitors. Detectors 108, 115 are configured to measure the amplitude of the respective adjusted continuous wave signal and the modulated continuous wave signal.
    [0084] The measured amplitude values are applied to amplitude adjuster [0084] 110 which comprises a feedback amplifier configuration in the depicted embodiment. The illustrated analog implementation of amplitude adjuster 110 is configured to drive variable attenuator 105 to equalize the amplitudes of the adjusted continuous wave signal and the modulated continuous wave signal. Amplitude adjuster 110 is configured to compare the amplitudes of the adjusted continuous wave signal and the received return link communication comprising the modulated continuous wave signal. Thereafter, amplitude adjuster 110 is operable to output a control signal to variable attenuator 105 to match the amplitudes of the respective signals. Other configurations of amplitude adjuster 110 are possible.
    [0085] Referring again to FIG. 7, coupler [0085] 109 is configured to sum the adjusted continuous wave signal and the received modulated continuous wave signal to reduce the amplitude of the modulated continuous wave signal. The summed continuous wave signal or return link communication is applied to a coupler 118. Coupler 118 is configured to apply the summed signal to low noise amplifier (LNA) 119 and amplitude detector 120. Amplitude detector 120 is configured to measure the amplitude of the summed signal and apply an output signal to a phase adjuster 121.
    [0086] Phase adjuster [0086] 121 is controllable responsive to amplitude adjuster 110. Once amplitude adjuster 110 and variable attenuator 105 have matched the amplitudes of the adjusted continuous wave signal and the received return link communication, amplitude adjuster indicates the match to phase adjuster 121 via a connection 122. Thereafter, phase adjuster 121 operates to select an appropriate phase shift of the amplitude adjusted local continuous wave signal.
    [0087] In the described embodiment, phase adjuster [0087] 121 is configured to search across 360° of possible phase adjustments to detect a phase adjustment of the local continuous wave signal which provides maximum reduction of amplitude of the received modulated continuous wave signal at the continuous wave signal frequency. In particular, adaptive canceler 97 adjusts the phase of the local continuous wave signal following matching of amplitudes of the local continuous wave signal and the received modulated continuous wave signal as indicated via connection 122.
    [0088] Referring to FIG. 9, a graphical illustration of the amplitude of the summed return link communication, represented by reference numeral [0088] 136, is illustrated with respect to corresponding plural phase adjustments of the local continuous wave signal. In the depicted illustration, it is shown that a local minimum value 130 corresponds to approximately 150°. For such a situation following searching of 360°, phase adjuster 121 will apply an appropriate control signal to phase shifter 106 to implement the desired phase shift of approximately 150° to minimize the amplitude of the bleed through of the wireless continuous wave signal within the received return link communication.
    [0089] Referring again to FIG. 7, the summed return link communication is applied to low noise amplifier [0089] 119 and processing circuitry 96. Phase adjuster 121 is operable to continuously monitor the amplitude of the summed return link communication and provide appropriate adjustments using control signals applied to phase shifter 106 to minimize the amplitude of the continuous wave signal within the summed return link communication applied to LNA 119.
    [0090] Referring to FIG. 10, exemplary embodiments of amplitude detector [0090] 120 and phase adjuster 121 are illustrated. Amplitude detector 120 includes discrete components comprising a diode, resistor and capacitor.
    [0091] Phase adjuster [0091] 121 comprises an analog-to-digital converter 124, processor 125 and digital-to-analog converter 126. Processor 125 can be configured to execute appropriate algorithms to implement sequential phase shifts of the local signal from 0° to 360°. The incremental step sizes can be adjusted. Therefore, processor 125 can compare the amplitudes of the summed return link communication signal responsive to various phase adjustments implemented by phase shifter 106. Following selection of an appropriate phase shift, phase adjuster 121 can continue to monitor the amplitude of the summed return link communication and update the phase shift as necessary to maintain maximum reduction of the continuous wave signal within the return link communication during communications. The depicted configurations of detector 120 and phase adjuster 121 are illustrative and other configurations can be utilized.
    [0092] Referring to FIG. 11 and FIG. 12, the received return link communication applied to adaptive canceler [0092] 97 and the summed return link communication output from adaptive canceler 97 are illustrated. The received return link communication comprising the modulated continuous wave signal is illustrated as signal 132 in FIG. 11. The summed return link communication is represented by signal 136 of FIG. 12.
    [0093] Signal [0093] 132 comprises a carrier component 133 and side band components 134. In the described embodiment, carrier 133 is centered at a frequency of 2.44 GHz and subcarrier side band components 134 are depicted at locations +/−600 kHz of the carrier component 133. Signal 136 similarly comprises a carrier component 137 and side band components 138. Signal 136 includes carrier component 137 at a frequency of 2.44 GHz and side band components 138 at locations +/−600 kHz of the carrier component 137.
    [0094] As illustrated, the output summed return link communication signal [0094] 136 has a carrier component 137 having a reduced amplitude compared with the carrier component 133 of the received return link communication signal 132. Preferably, the amplitude of side band components 138 of summed return link communication signal 136 are maintained during the reduction of amplitude of the carrier component 137 as illustrated in FIG. 11 and FIG. 12.
    [0095] In the depicted illustrations of FIG. 11 and FIG. 12, carrier component [0095] 137 of signal 136 is approximately 20 dBm less than carrier component 133 of received return link communication 132. Such indicates the reduction of amplitude of the return link communication signal at the frequency of the wireless continuous wave signal (e.g., 2.44 GHz) utilizing adaptive canceler 97.
    [0096] Referring to FIG. 13, a diagrammatic illustration of forward link communication [0096] 27 and return link communication 29 is shown. Initially, forward link communication 27 is communicated using transmit antenna X1 of interrogator 26. Following an intermediate delay or guard band, return link communication 29 corresponding to remote communication device 12 is communicated.
    [0097] Individual return link communications [0097] 29 include a calibration period 140 followed by a preamble 141 and actual data 142. Matching of amplitudes of the local continuous wave signal and the received return link communication and cycling through phases from 0 to 360° utilizing phase adjuster 121 and phase shifter 106 preferably occurs during calibration period 140. The minimum level 130 within the summed return link communication signal is preferably determined during calibration period 140.
    [0098] Preamble [0098] 141 can be utilized to synchronize the processing circuitry 96 of receiver 95 with the actual return link communication 29 being received. Thereafter, data 142 communicated from remote communication device 12 is received. Adaptive canceler 97 is configured to make adjustments as necessary to the amplitude and phase of the local continuous signal during preamble period 141 and data period 142 to maintain maximum reduction of the continuous wave signal within the received return link communication 29.
    [0099] In compliance with the statute, the invention has been described in language more or less specific as to structural and methodical features. It is to be understood, however, that the invention is not limited to the specific features shown and described, since the means herein disclosed comprise preferred forms of putting the invention into effect. The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims appropriately interpreted in accordance with the doctrine of equivalents. [0099]
    权利要求:
    Claims (52)
    [1" id="US-20010001758-A1-CLM-00001] 1. A backscatter communication system comprising:
    an interrogator including a transmitter configured to output a forward link communication and a receiver configured to receive a return link communication having a carrier signal, the receiver being configured to reduce the amplitude of the carrier signal of the return link communication; and
    a communication device configured to modulate the carrier signal to communicate the return link communication responsive to reception of the forward link communication.
    [2" id="US-20010001758-A1-CLM-00002] 2. The backscatter communication system according to
    claim 1 wherein the communication device comprises a radio frequency identification device.
    [3" id="US-20010001758-A1-CLM-00003] 3. The backscatter communication system according to
    claim 1 wherein the communication device comprises a remote intelligent communication device.
    [4" id="US-20010001758-A1-CLM-00004] 4. The backscatter communication system according to
    claim 1 wherein the carrier signal comprises a continuous wave signal.
    [5" id="US-20010001758-A1-CLM-00005] 5. The backscatter communication system according to
    claim 1 wherein the interrogator comprises a coherent interrogator.
    [6" id="US-20010001758-A1-CLM-00006] 6. The backscatter communication system according to
    claim 1 wherein the transmitter is configured to apply a local continuous wave signal to the receiver, and the receiver is configured to receive the local continuous wave signal, adjust the amplitude and phase of the local continuous wave signal to provide an adjusted continuous wave signal, and sum the adjusted continuous wave signal with the return link communication.
    [7" id="US-20010001758-A1-CLM-00007] 7. The backscatter communication system according to
    claim 6 wherein the receiver is configured to match the amplitude of the local continuous wave signal with the amplitude of the return link communication.
    [8" id="US-20010001758-A1-CLM-00008] 8. A backscatter system interrogator comprising:
    a receiver configured to receive a return link communication comprising a modulated continuous wave signal comprising a radio frequency continuous wave signal having a first frequency and a modulation signal having a different frequency, the receiver being further configured to reduce the amplitude of the return link communication at the frequency of the radio frequency continuous wave signal.
    [9" id="US-20010001758-A1-CLM-00009] 9. The backscatter system interrogator according to
    claim 8 further comprising a transmitter configured to output a forward link communication, the radio frequency continuous wave signal and a local continuous wave signal.
    [10" id="US-20010001758-A1-CLM-00010] 10. The backscatter system interrogator according to
    claim 9 wherein the receiver and transmitter are coherent.
    [11" id="US-20010001758-A1-CLM-00011] 11. The backscatter system interrogator according to
    claim 9 wherein the receiver is configured to receive the local continuous wave signal, adjust the amplitude and phase of the local continuous wave signal to provide an adjusted continuous wave signal, and sum the adjusted continuous wave signal with the modulated continuous wave signal.
    [12" id="US-20010001758-A1-CLM-00012] 12. The backscatter system interrogator according to
    claim 11 wherein the receiver is configured to match the amplitude of the local continuous wave signal with the amplitude of the modulated continuous wave signal.
    [13" id="US-20010001758-A1-CLM-00013] 13. The backscatter system interrogator according to
    claim 9 wherein the transmitter and receiver are configured to communicate with a radio frequency identification device.
    [14" id="US-20010001758-A1-CLM-00014] 14. A coherent backscatter system interrogator comprising:
    a transmitter configured to communicate a wireless forward link communication, a wireless continuous wave signal and a local continuous wave signal; and
    a receiver configured to receive the local continuous wave signal from the transmitter and wireless return link communications comprising modulated continuous wave signals, the receiver being configured to reduce the amplitude of the return link communications using the local continuous wave signal received from the transmitter.
    [15" id="US-20010001758-A1-CLM-00015] 15. The coherent backscatter system interrogator according to
    claim 14 wherein the transmitter and receiver are configured to communicate with a radio frequency identification device.
    [16" id="US-20010001758-A1-CLM-00016] 16. The coherent backscatter system interrogator according to
    claim 14 wherein the receiver is configured to receive the local continuous wave signal, adjust the amplitude and phase of the local continuous wave signal to provide an adjusted continuous wave signal, and sum the adjusted continuous wave signal with the modulated continuous wave signal.
    [17" id="US-20010001758-A1-CLM-00017] 17. The coherent backscatter system interrogator according to
    claim 16 wherein the receiver is configured to match the amplitude of the local continuous wave signal with the amplitude of an individual modulated continuous wave signal.
    [18" id="US-20010001758-A1-CLM-00018] 18. The coherent backscatter system interrogator according to
    claim 14 wherein the wireless continuous wave signal and the local continuous wave signal have a common frequency, and the receiver is configured to reduce the amplitude of the return link communications at the common frequency.
    [19" id="US-20010001758-A1-CLM-00019] 19. A method of communicating in a backscatter system comprising:
    transmitting a forward link communication;
    transmitting a wireless continuous wave signal;
    receiving the forward link communication;
    modulating the wireless continuous wave signal responsive to the receiving the forward link communication, the modulating providing a modulated continuous wave signal;
    receiving the modulated continuous wave signal; and
    reducing the amplitude of the modulated continuous wave signal.
    [20" id="US-20010001758-A1-CLM-00020] 20. The method according to
    claim 19 wherein the transmitting the wireless continuous wave signal comprises transmitting the wireless continuous wave signal at a frequency and the reducing comprises reducing the amplitude of the modulated continuous wave signal at the frequency.
    [21" id="US-20010001758-A1-CLM-00021] 21. The method according to
    claim 19 wherein the transmitting the wireless continuous wave signal comprises transmitting at a first frequency and the modulating comprises modulating the wireless continuous wave signal using a subcarrier signal having a second frequency.
    [22" id="US-20010001758-A1-CLM-00022] 22. The method according to
    claim 21 wherein the reducing comprises reducing the amplitude of the modulated continuous wave signal at the first frequency.
    [23" id="US-20010001758-A1-CLM-00023] 23. The method according to
    claim 19 wherein the transmittings individually comprise transmitting using an interrogator and the modulating comprises modulating using a radio frequency identification device.
    [24" id="US-20010001758-A1-CLM-00024] 24. The method according to
    claim 19 wherein the modulating comprises selectively reflecting the wireless continuous wave signal.
    [25" id="US-20010001758-A1-CLM-00025] 25. The method according to
    claim 19 further comprising providing a local continuous wave signal and the reducing comprises reducing the amplitude using the local continuous wave signal.
    [26" id="US-20010001758-A1-CLM-00026] 26. The method according to
    claim 25 wherein the reducing comprises:
    matching the amplitude of the local continuous wave signal with the amplitude of the modulated continuous wave signal;
    adjusting the phase of the local continuous wave signal following the matching; and
    summing the local continuous wave signal and the modulated continuous wave signal following the adjusting.
    [27" id="US-20010001758-A1-CLM-00027] 27. The method according to
    claim 26 wherein the adjusting comprises searching for a phase which provides maximum reduction of the amplitude of the modulated continuous wave signal at a frequency of the wireless continuous wave signal.
    [28" id="US-20010001758-A1-CLM-00028] 28. A backscatter communications method comprising:
    transmitting a forward link communication and a wireless continuous wave signal using an interrogator;
    receiving the forward link communication using a remote communication device;
    communicating a return link communication comprising a modulated continuous wave signal responsive to the receiving the forward link communication, the communicating including modulating the wireless continuous wave signal using the remote communication device;
    receiving the modulated continuous wave signal using the interrogator; and
    reducing the amplitude of the modulated continuous wave signal using the interrogator.
    [29" id="US-20010001758-A1-CLM-00029] 29. The method according to
    claim 28 wherein the communicating comprises reflecting the wireless continuous wave signal using a subcarrier signal.
    [30" id="US-20010001758-A1-CLM-00030] 30. The method according to
    claim 28 wherein the communicating comprises modulating the wireless continuous wave signal providing a carrier component and side band components.
    [31" id="US-20010001758-A1-CLM-00031] 31. The method according to
    claim 30 wherein the reducing comprises reducing the amplitude of the carrier component.
    [32" id="US-20010001758-A1-CLM-00032] 32. The method according to
    claim 31 wherein the reducing comprises substantially maintaining the amplitude of the side band components during the reducing.
    [33" id="US-20010001758-A1-CLM-00033] 33. The method according to
    claim 28 wherein the transmitting comprises transmitting the wireless continuous wave signal at a frequency and the reducing comprises reducing the amplitude of the modulated continuous wave signal at the frequency.
    [34" id="US-20010001758-A1-CLM-00034] 34. The method according to
    claim 28 wherein the receiving the forward link communication comprises receiving using a radio frequency identification device.
    [35" id="US-20010001758-A1-CLM-00035] 35. The method according to
    claim 28 wherein the transmitting comprises transmitting radio frequency signals.
    [36" id="US-20010001758-A1-CLM-00036] 36. The method according to
    claim 28 further comprising providing a local continuous wave signal and the reducing comprises reducing using the local continuous wave signal.
    [37" id="US-20010001758-A1-CLM-00037] 37. A coherent backscatter communication method comprising:
    transmitting a wireless forward link communication;
    transmitting a continuous wave signal;
    providing the continuous wave signal as a local signal;
    receiving the wireless forward link communication;
    communicating a wireless return link communication including modulating the continuous wave signal following the receiving;
    receiving the wireless return link communication; and
    reducing the amplitude of the wireless return link communication using the local signal.
    [38" id="US-20010001758-A1-CLM-00038] 38. The method according to
    claim 37 wherein the communicating comprises reflecting the transmitted continuous wave signal.
    [39" id="US-20010001758-A1-CLM-00039] 39. The method according to
    claim 37 wherein the communicating comprises modulating the continuous wave signal providing a carrier component and side band components.
    [40" id="US-20010001758-A1-CLM-00040] 40. The method according to
    claim 39 wherein the reducing comprises reducing the amplitude of the carrier component.
    [41" id="US-20010001758-A1-CLM-00041] 41. The method according to
    claim 40 wherein the reducing comprises substantially maintaining the amplitude of the side band components during the reducing.
    [42" id="US-20010001758-A1-CLM-00042] 42. The method according to
    claim 37 wherein the transmitting a continuous wave signal comprises transmitting a continuous wave signal having a frequency and the reducing comprises reducing the amplitude of the modulated continuous wave signal at the frequency.
    [43" id="US-20010001758-A1-CLM-00043] 43. The method according to
    claim 37 wherein the receiving the wireless forward link communication comprises receiving using a radio frequency identification device.
    [44" id="US-20010001758-A1-CLM-00044] 44. The method according to
    claim 37 wherein the transmittings individually comprise transmitting radio frequency signals using an interrogator.
    [45" id="US-20010001758-A1-CLM-00045] 45. A method of communicating within a coherent backscatter communication system, the method comprising:
    outputting a forward link communication;
    outputting a wireless continuous wave signal;
    providing a local continuous wave signal;
    communicating a modulated continuous wave signal responsive to the outputting the forward link communication;
    receiving the modulated continuous wave signal; and
    reducing the amplitude of the modulated continuous wave signal including:
    matching the amplitude of the local continuous wave signal with the amplitude of the received modulated continuous wave signal;
    adjusting the phase of the local continuous wave signal following the matching providing an adjusted continuous wave signal; and
    summing the adjusted continuous wave signal with the modulated continuous wave signal.
    [46" id="US-20010001758-A1-CLM-00046] 46. The method according to
    claim 45 wherein the adjusting comprises searching for a phase which provides maximum reduction of the amplitude of the modulated continuous wave signal at a frequency of the wireless continuous wave signal.
    [47" id="US-20010001758-A1-CLM-00047] 47. The method according to
    claim 45 wherein the communicating comprises reflecting the wireless continuous wave signal.
    [48" id="US-20010001758-A1-CLM-00048] 48. The method according to
    claim 45 wherein the outputtings individually comprise transmitting using an interrogator and the communicating comprises communicating using a radio frequency identification device.
    [49" id="US-20010001758-A1-CLM-00049] 49. The method according to
    claim 45 wherein the communicating comprises modulating the continuous wave signal providing a modulated continuous wave signal having a carrier component and side band components.
    [50" id="US-20010001758-A1-CLM-00050] 50. The method according to
    claim 49 wherein the reducing comprises reducing the amplitude of the carrier component.
    [51" id="US-20010001758-A1-CLM-00051] 51. The method according to
    claim 50 further comprising substantially maintaining the amplitude of the side band components during the reducing.
    [52" id="US-20010001758-A1-CLM-00052] 52. A method of reducing power within a modulated return link continuous wave signal of a coherent backscatter communication system including an interrogator and a remote communication device, the method comprising:
    transmitting a radio frequency forward link communication;
    transmitting a radio frequency continuous wave signal having a first frequency;
    providing a local continuous wave signal having the first frequency;
    receiving the radio frequency forward link communication;
    modulating the radio frequency continuous wave signal following the receiving the radio frequency forward link communication, the modulating comprising reflecting the radio frequency continuous wave signal using a modulation signal having a second frequency and providing a modulated continuous wave signal having a carrier component and plural side band components;
    receiving the modulated continuous wave signal; and
    reducing the amplitude of the carrier component of the modulated continuous wave signal including:
    matching the amplitude of the local continuous wave signal with the amplitude of the modulated continuous wave signal;
    adjusting the phase of the local continuous wave signal following the matching; and
    summing the local continuous wave signal and the modulated continuous wave signal following the adjusting.
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    同族专利:
    公开号 | 公开日
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    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    US20010055949A1|2000-05-08|2001-12-27|Hock Law|Co-located frequency-agile system and method|
    US20030181229A1|2001-11-21|2003-09-25|Forster Ian J.|Wireless communication device interconnectivity|
    US20040229613A1|2003-05-14|2004-11-18|Skorpik James R.|Wireless communication devices and movement monitoring methods|
    US20060046774A1|2003-10-10|2006-03-02|Sony Corporation|Radio communication apparatus|
    WO2006037241A1|2004-10-08|2006-04-13|Elektrobit Ag|Method and device for suppressing a transmitted signal in a receiver of an rfid write/read unit|
    WO2006043876A1|2004-10-22|2006-04-27|Wavelogics Ab|Encoding of rfid|
    WO2006070237A3|2004-12-30|2006-10-19|Nokia Corp|Ultra wideband radio frequency identification techniques|
    US20060290438A1|2004-02-27|2006-12-28|Micron Technology, Inc.|Microstrip line dielectric overlay|
    US20070024444A1|2003-08-11|2007-02-01|Sony Corporation|Radio communication system and wireless communication device|
    US20070060075A1|2005-09-14|2007-03-15|Neology, Inc.|Systems and methods for an rf nulling scheme in rfid|
    US20120013446A1|2010-07-14|2012-01-19|Sony Corporation|Communication system and communication apparatus|US3195073A|1961-07-26|1965-07-13|Texas Instruments Inc|Single-sideband suppressed carrier signal generator|
    US3568197A|1969-12-05|1971-03-02|Nasa|Antenna array phase quadrature tracking system|
    US3733602A|1971-05-20|1973-05-15|Motorola Inc|Microwave intrusion detecting system and apparatus|
    US3848191A|1972-07-07|1974-11-12|Rca Corp|Asynchronous pulse receiver|
    US3914762A|1973-12-27|1975-10-21|Rca Corp|Electronic identification system|
    GB1500289A|1974-06-03|1978-02-08|Rca Corp|Homodyne communication system|
    US4075632A|1974-08-27|1978-02-21|The United States Of America As Represented By The United States Department Of Energy|Interrogation, and detection system|
    US4149121A|1977-06-23|1979-04-10|Ncr Corporation|Four phase to two phase correlator|
    US4364043A|1979-05-30|1982-12-14|The University Of Adelaide|Efficient object identification system|
    JPS56132828A|1980-03-24|1981-10-17|Nippon Telegr & Teleph Corp <Ntt>|Space diversity receiving device|
    IT1142442B|1981-05-11|1986-10-08|Selenia Ind Elettroniche|ADAPTIVE POLARIZATION RECEIVER FOR THE CANCELLATION OF INTENTIONAL DISORDERS IN A RADAR SYSTEM|
    US4725841A|1983-06-30|1988-02-16|X-Cyte, Inc.|System for interrogating a passive transponder carrying phase-encoded information|
    US4647931A|1984-11-29|1987-03-03|Rca Corporation|Dual frequency identification system|
    JPS62264778A|1986-05-12|1987-11-17|Toshiba Corp|Agc circuit|
    EP0247612B1|1986-05-30|1993-08-04|Sharp Kabushiki Kaisha|Microwave data transmission apparatus|
    US4799062A|1987-04-27|1989-01-17|Axonn Corporation|Radio position determination method and apparatus|
    US5345504A|1988-03-10|1994-09-06|Scientific-Atlanta, Inc.|Differential compensation control for off-premises CATV system|
    GB2223908A|1988-10-14|1990-04-18|Philips Electronic Associated|Continuously transmitting and receiving radar|
    GB2226204A|1988-12-07|1990-06-20|Philips Electronic Associated|Continuously transmitting and receiving radar|
    US5260707A|1988-12-22|1993-11-09|Hughes Aircraft Company|Phase coherent interference signal suppression system and method|
    US5134630A|1989-04-12|1992-07-28|National Research Development Corporation|Method and apparatus for transparent tone-in-band transmitter, receiver and system processing|
    US5657317A|1990-01-18|1997-08-12|Norand Corporation|Hierarchical communication system using premises, peripheral and vehicular local area networking|
    US5640151A|1990-06-15|1997-06-17|Texas Instruments Incorporated|Communication system for communicating with tags|
    US5231273A|1991-04-09|1993-07-27|Comtec Industries|Inventory management system|
    US5305008A|1991-08-12|1994-04-19|Integrated Silicon Design Pty. Ltd.|Transponder system|
    US5365516A|1991-08-16|1994-11-15|Pinpoint Communications, Inc.|Communication system and method for determining the location of a transponder unit|
    US5369793A|1991-12-12|1994-11-29|Raytheon Company|RF receiver adapted to process received RF pulses and reject RF continuous wave signals|
    US5349355A|1993-01-21|1994-09-20|The United States Of America As Represented By The Secretary Of The Navy|Credential tracking system|
    JPH06261010A|1993-03-04|1994-09-16|Fujitsu Ltd|Fading simulation method and fading simulator|
    JPH06260866A|1993-03-04|1994-09-16|Mitsubishi Electric Corp|Automatic output power control circuit device|
    US5477215A|1993-08-02|1995-12-19|At&T Corp.|Arrangement for simultaneously interrogating a plurality of portable radio frequency communication devices|
    US5471212A|1994-04-26|1995-11-28|Texas Instruments Incorporated|Multi-stage transponder wake-up, method and structure|
    ZA95605B|1994-04-28|1995-12-20|Qualcomm Inc|Method and apparatus for automatic gain control and dc offset cancellation in quadrature receiver|
    US5610940A|1994-09-09|1997-03-11|Omnipoint Corporation|Method and apparatus for noncoherent reception and correlation of a continous phase modulated signal|
    US5584065A|1994-10-13|1996-12-10|American Nucleonics Corporation|Interference cancellation system employing an I/Q quadrature rotator|
    US5691978A|1995-04-07|1997-11-25|Signal Science, Inc.|Self-cancelling full-duplex RF communication system|
    US5649296A|1995-06-19|1997-07-15|Lucent Technologies Inc.|Full duplex modulated backscatter system|
    ZA965340B|1995-06-30|1997-01-27|Interdigital Tech Corp|Code division multiple access communication system|
    US5940006A|1995-12-12|1999-08-17|Lucent Technologies Inc.|Enhanced uplink modulated backscatter system|
    US6130602A|1996-05-13|2000-10-10|Micron Technology, Inc.|Radio frequency data communications device|
    US6058374A|1996-06-20|2000-05-02|Northrop Grumman Corporation|Inventorying method and system for monitoring items using tags|
    US5926747A|1996-09-05|1999-07-20|Airnet Communications Corp.|Method and apparatus for dynamically optimizing the forward-link transmit power of a broadband multi-carrier radio signal|
    JP3147306B2|1996-10-17|2001-03-19|ピンポイントコーポレイション|Item tracking system|
    US6353406B1|1996-10-17|2002-03-05|R.F. Technologies, Inc.|Dual mode tracking system|
    US6107910A|1996-11-29|2000-08-22|X-Cyte, Inc.|Dual mode transmitter/receiver and decoder for RF transponder tags|
    US6289209B1|1996-12-18|2001-09-11|Micron Technology, Inc.|Wireless communication system, radio frequency communications system, wireless communications method, radio frequency communications method|
    US5842118A|1996-12-18|1998-11-24|Micron Communications, Inc.|Communication system including diversity antenna queuing|
    US5970388A|1996-12-26|1999-10-19|Will; Craig A.|Wireless system for indicating an incoming telephone call and controlling its transfer|
    US6084530A|1996-12-30|2000-07-04|Lucent Technologies Inc.|Modulated backscatter sensor system|
    US5784686A|1996-12-31|1998-07-21|Lucent Technologies Inc.|IQ combiner technology in modulated backscatter system|
    US6046683A|1996-12-31|2000-04-04|Lucent Technologies Inc.|Modulated backscatter location system|
    US5952922A|1996-12-31|1999-09-14|Lucent Technologies Inc.|In-building modulated backscatter system|
    US6456668B1|1996-12-31|2002-09-24|Lucent Technologies Inc.|QPSK modulated backscatter system|
    US5920287A|1997-01-21|1999-07-06|Widata Corporation|Radio location system for precisely tracking objects by RF transceiver tags which randomly and repetitively emit wideband identification signals|
    US5914671A|1997-02-27|1999-06-22|Micron Communications, Inc.|System and method for locating individuals and equipment, airline reservation system, communication system|
    US6064320A|1997-04-04|2000-05-16|Texas Instruments Incorporated|Automatic vehicle identification system capable of vehicle lane discrimination|
    US6148048A|1997-09-26|2000-11-14|Cirrus Logic, Inc.|Receive path implementation for an intermediate frequency transceiver|
    US5983082A|1997-10-31|1999-11-09|Motorola, Inc.|Phase quadrature signal generator having a variable phase shift network|
    US6353729B1|1997-11-14|2002-03-05|Nortel Networks Limited|Using an RF repeater in CDMA applications to combat interference caused by a non-collocated radio|
    US6122329A|1998-02-06|2000-09-19|Intermec Ip Corp.|Radio frequency identification interrogator signal processing system for reading moving transponders|
    US6313737B1|1998-06-23|2001-11-06|Marconi Commerce Systems Inc.|Centralized transponder arbitration|
    US6192222B1|1998-09-03|2001-02-20|Micron Technology, Inc.|Backscatter communication systems, interrogators, methods of communicating in a backscatter system, and backscatter communication methods|
    US6324387B1|1998-12-29|2001-11-27|Philips Electronics N.A. Corp.|LNA control-circuit for receive closed loop automatic gain control|
    US6603391B1|1999-03-09|2003-08-05|Micron Technology, Inc.|Phase shifters, interrogators, methods of shifting a phase angle of a signal, and methods of operating an interrogator|
    US7592898B1|1999-03-09|2009-09-22|Keystone Technology Solutions, Llc|Wireless communication systems, interrogators and methods of communicating within a wireless communication system|
    US6356764B1|1999-03-09|2002-03-12|Micron Technology, Inc.|Wireless communication systems, interrogators and methods of communicating within a wireless communication system|
    US6356230B1|1999-08-20|2002-03-12|Micron Technology, Inc.|Interrogators, wireless communication systems, methods of operating an interrogator, methods of monitoring movement of a radio frequency identification device, methods of monitoring movement of a remote communication device and movement monitoring methods|
    US6721549B2|1999-12-29|2004-04-13|Samsung Electronics Co., Ltd.|Low-noise amplifier for a mobile communication terminal|
    US7023341B2|2003-02-03|2006-04-04|Ingrid, Inc.|RFID reader for a security network|
    US6903656B1|2003-05-27|2005-06-07|Applied Wireless Identifications Group, Inc.|RFID reader with multiple antenna selection and automated antenna matching|
    US7369811B2|2004-04-30|2008-05-06|Wj Communications, Inc.|System and method for sensitivity optimization of RF receiver using adaptive nulling|US6057779A|1997-08-14|2000-05-02|Micron Technology, Inc.|Method of controlling access to a movable container and to a compartment of a vehicle, and a secure cargo transportation system|
    US6356535B1|1998-02-04|2002-03-12|Micron Technology, Inc.|Communication systems and methods of communicating|
    US6072801A|1998-02-19|2000-06-06|Micron Technology, Inc.|Method of addressing messages, method of establishing wireless communications, and communications system|
    USRE43382E1|1998-02-19|2012-05-15|Round Rock Research, Llc|Method of addressing messages and communications systems|
    US6061344A|1998-02-19|2000-05-09|Micron Technology, Inc.|Method of addressing messages and communications system|
    US6118789A|1998-02-19|2000-09-12|Micron Technology, Inc.|Method of addressing messages and communications system|
    US6275476B1|1998-02-19|2001-08-14|Micron Technology, Inc.|Method of addressing messages and communications system|
    US6192222B1|1998-09-03|2001-02-20|Micron Technology, Inc.|Backscatter communication systems, interrogators, methods of communicating in a backscatter system, and backscatter communication methods|
    US10973397B2|1999-03-01|2021-04-13|West View Research, Llc|Computerized information collection and processing apparatus|
    US8636648B2|1999-03-01|2014-01-28|West View Research, Llc|Endoscopic smart probe|
    US6356764B1|1999-03-09|2002-03-12|Micron Technology, Inc.|Wireless communication systems, interrogators and methods of communicating within a wireless communication system|
    US6603391B1|1999-03-09|2003-08-05|Micron Technology, Inc.|Phase shifters, interrogators, methods of shifting a phase angle of a signal, and methods of operating an interrogator|
    US7592898B1|1999-03-09|2009-09-22|Keystone Technology Solutions, Llc|Wireless communication systems, interrogators and methods of communicating within a wireless communication system|
    US8065155B1|1999-06-10|2011-11-22|Gazdzinski Robert F|Adaptive advertising apparatus and methods|
    US7710273B2|1999-09-02|2010-05-04|Round Rock Research, Llc|Remote communication devices, radio frequency identification devices, wireless communication systems, wireless communication methods, radio frequency identification device communication methods, and methods of forming a remote communication device|
    US7236742B2|2001-06-18|2007-06-26|Brigham Young University|System and method for wireless data transfer for a mobile unit|
    US8021778B2|2002-08-09|2011-09-20|Infinite Power Solutions, Inc.|Electrochemical apparatus with barrier layer protected substrate|
    US8236443B2|2002-08-09|2012-08-07|Infinite Power Solutions, Inc.|Metal film encapsulation|
    US8445130B2|2002-08-09|2013-05-21|Infinite Power Solutions, Inc.|Hybrid thin-film battery|
    US8404376B2|2002-08-09|2013-03-26|Infinite Power Solutions, Inc.|Metal film encapsulation|
    US7993773B2|2002-08-09|2011-08-09|Infinite Power Solutions, Inc.|Electrochemical apparatus with barrier layer protected substrate|
    US8394522B2|2002-08-09|2013-03-12|Infinite Power Solutions, Inc.|Robust metal film encapsulation|
    US20070264564A1|2006-03-16|2007-11-15|Infinite Power Solutions, Inc.|Thin film battery on an integrated circuit or circuit board and method thereof|
    US8431264B2|2002-08-09|2013-04-30|Infinite Power Solutions, Inc.|Hybrid thin-film battery|
    US7893840B2|2003-03-03|2011-02-22|Veroscan, Inc.|Interrogator and interrogation system employing the same|
    US7019650B2|2003-03-03|2006-03-28|Caducys, L.L.C.|Interrogator and interrogation system employing the same|
    US8063760B2|2003-03-03|2011-11-22|Veroscan, Inc.|Interrogator and interrogation system employing the same|
    US8174366B2|2003-03-03|2012-05-08|Veroscan, Inc.|Interrogator and interrogation system employing the same|
    US8542717B2|2003-03-03|2013-09-24|Veroscan, Inc.|Interrogator and interrogation system employing the same|
    US8728285B2|2003-05-23|2014-05-20|Demaray, Llc|Transparent conductive oxides|
    US7068169B2|2003-06-05|2006-06-27|Motorola, Inc.|Use of a subcarrier in an organic semiconductor radio frequency identification system|
    WO2004109583A1|2003-06-06|2004-12-16|Stemco Llc|Wireless communication device, system for communication and communication method|
    US20050024187A1|2003-07-28|2005-02-03|Kranz Mark J.|System and method for optimizing power usage in a radio frequency communication device|
    JP4254419B2|2003-08-20|2009-04-15|ブラザー工業株式会社|Interrogator for communication system|
    US7218214B2|2003-10-27|2007-05-15|David R. Werner|Auxiliary safety light system|
    US7436308B2|2004-04-13|2008-10-14|Impinj, Inc.|Adjusting RFID waveform shape in view of signal from another reader|
    US7417548B2|2004-04-13|2008-08-26|Impinj, Inc.|Adjusting RFID waveform shape in view of signal from an RFID tag|
    US7427024B1|2003-12-17|2008-09-23|Gazdzinski Mark J|Chattel management apparatus and methods|
    JP2007526586A|2004-03-03|2007-09-13|ケイデュシィズエルエルシィ|Interrogation system using interrogators and the like|
    US7830262B1|2006-04-25|2010-11-09|Impinj, Inc.|Adjusting communication parameters while inventorying RFID tags|
    US7671720B1|2004-09-01|2010-03-02|Alien Technology Corporation|Method and appratus for removing distortion in radio frequency signals|
    US7501948B2|2004-09-29|2009-03-10|Lone Star Ip Holdings, Lp|Interrogation system employing prior knowledge about an object to discern an identity thereof|
    US7959769B2|2004-12-08|2011-06-14|Infinite Power Solutions, Inc.|Deposition of LiCoO2|
    CN101931097B|2004-12-08|2012-11-21|希莫菲克斯公司|Deposition of LiCoO2|
    US7573366B2|2005-03-31|2009-08-11|Symbol Technologies, Inc.|Method and system for RF activation of RF interrogators|
    US7221308B2|2005-04-19|2007-05-22|Northrop Grumman Corporation|Joint stars embedded data link|
    US20060238304A1|2005-04-21|2006-10-26|Sean Loving|System and method for adapting an FRID tag reader to its environment|
    US20060238302A1|2005-04-21|2006-10-26|Sean Loving|System and method for configuring an RFID reader|
    US20060253415A1|2005-04-21|2006-11-09|Sayan Chakraborty|Data-defined communication device|
    US7659819B2|2005-04-21|2010-02-09|Skyetek, Inc.|RFID reader operating system and associated architecture|
    WO2006116085A2|2005-04-21|2006-11-02|Skyetek, Inc.|System and method for combining rfid tag memory|
    US20060238305A1|2005-04-21|2006-10-26|Sean Loving|Configurable RFID reader|
    US20060238303A1|2005-04-21|2006-10-26|Sean Loving|Adaptable RFID reader|
    FI119670B|2005-07-08|2009-01-30|Valtion Teknillinen|RFID reading equipment and method|
    US20070206786A1|2005-08-31|2007-09-06|Skyetek, Inc.|Rfid security system|
    US20070046467A1|2005-08-31|2007-03-01|Sayan Chakraborty|System and method for RFID reader to reader communication|
    US20070046431A1|2005-08-31|2007-03-01|Skyetek, Inc.|System and method for combining RFID tag memory|
    EP1938483B1|2005-09-21|2015-07-08|Intermec IP Corp.|Stochastic communication protocol method and system for radio frequency identificationtags based on coalition formation, such as for tag-to-tag communication|
    US7570164B2|2005-12-30|2009-08-04|Skyetek, Inc.|System and method for implementing virtual RFID tags|
    US20080042830A1|2005-12-30|2008-02-21|Skyetek, Inc.|Virtual rfid-based tag sensor|
    US20080022160A1|2005-12-30|2008-01-24|Skyetek, Inc.|Malware scanner for rfid tags|
    US20070206797A1|2006-03-01|2007-09-06|Skyetek, Inc.|Seamless rfid tag security system|
    US7664461B2|2006-03-02|2010-02-16|Broadcom Corporation|RFID reader architecture|
    US8120461B2|2006-04-03|2012-02-21|Intermec Ip Corp.|Automatic data collection device, method and article|
    US20080131133A1|2006-05-17|2008-06-05|Blunt Shannon D|Low sinr backscatter communications system and method|
    KR100814002B1|2006-06-29|2008-03-14|삼성전자주식회사|Data recovery method and apparatus for radio frequency identification|
    AU2007281584A1|2006-07-29|2008-02-07|Powercast Corporation|RF power transmission network and method|
    US8062708B2|2006-09-29|2011-11-22|Infinite Power Solutions, Inc.|Masking of and material constraint for depositing battery layers on flexible substrates|
    US20080079547A1|2006-09-29|2008-04-03|Sensormatic Electronics Corporation|Radio frequency identification reader having a signal canceller and method thereof|
    US8197781B2|2006-11-07|2012-06-12|Infinite Power Solutions, Inc.|Sputtering target of Li3PO4 and method for producing same|
    US7973644B2|2007-01-30|2011-07-05|Round Rock Research, Llc|Systems and methods for RFID tag arbitration where RFID tags generate multiple random numbers for different arbitration sessions|
    US20080297326A1|2007-03-30|2008-12-04|Skyetek, Inc.|Low Cost RFID Tag Security And Privacy System And Method|
    US7859411B2|2007-03-30|2010-12-28|Skyetek, Inc.|RFID tagged item trajectory and location estimation system and method|
    US8669845B1|2007-03-30|2014-03-11|Vail Resorts, Inc.|RFID skier monitoring systems and methods|
    US20080290995A1|2007-03-30|2008-11-27|Skyetek, Inc.|System and method for optimizing communication between an rfid reader and an rfid tag|
    US8134452B2|2007-05-30|2012-03-13|Round Rock Research, Llc|Methods and systems of receiving data payload of RFID tags|
    US20090015407A1|2007-07-13|2009-01-15|Micron Technology, Inc.|Rifid tags and methods of designing rfid tags|
    US7777630B2|2007-07-26|2010-08-17|Round Rock Research, Llc|Methods and systems of RFID tags using RFID circuits and antennas having unmatched frequency ranges|
    US20090078763A1|2007-09-20|2009-03-26|Scolis TechnologiesPvt. Ltd.|Contact-less smart card reader|
    CN101425823A|2007-11-01|2009-05-06|西门子公司|Self-interference signal eliminating apparatus and method and RFID reader-writer|
    US20090153290A1|2007-12-14|2009-06-18|Farpointe Data, Inc., A California Corporation|Secure interface for access control systems|
    US8268488B2|2007-12-21|2012-09-18|Infinite Power Solutions, Inc.|Thin film electrolyte for thin film batteries|
    TWI441937B|2007-12-21|2014-06-21|Infinite Power Solutions Inc|Method for sputter targets for electrolyte films|
    US20090160648A1|2007-12-24|2009-06-25|Rfmicron, Inc.|Method and apparatus for bulk calibrating RFID tags|
    US20090179740A1|2008-01-10|2009-07-16|Intermec Ip Corp.|Radio frequency identificationmethod and apparatus for maximizing receive channel signal-to-noise ratio by adjusting phase to minimize noise|
    JP5705549B2|2008-01-11|2015-04-22|インフィニット パワー ソリューションズ， インコーポレイテッド|Thin film encapsulation for thin film batteries and other devices|
    KR101672254B1|2008-04-02|2016-11-08|사푸라스트 리써치 엘엘씨|Passive over/under voltage control and protection for energy storage devices associated with energy harvesting|
    US8179232B2|2008-05-05|2012-05-15|Round Rock Research, Llc|RFID interrogator with adjustable signal characteristics|
    US7852221B2|2008-05-08|2010-12-14|Round Rock Research, Llc|RFID devices using RFID circuits and antennas having unmatched frequency ranges|
    US8712334B2|2008-05-20|2014-04-29|Micron Technology, Inc.|RFID device using single antenna for multiple resonant frequency ranges|
    US8358783B2|2008-08-11|2013-01-22|Assa Abloy Ab|Secure wiegand communications|
    KR20110058793A|2008-08-11|2011-06-01|인피니트 파워 솔루션스, 인크.|Energy device with integral collector surface for electromagnetic energy harvesting and method thereof|
    EP2157526B1|2008-08-14|2014-04-30|Assa Abloy Ab|RFID reader with embedded attack detection heuristics|
    EP2332127A4|2008-09-12|2011-11-09|Infinite Power Solutions Inc|Energy device with integral conductive surface for data communication via electromagnetic energy and method thereof|
    WO2010042594A1|2008-10-08|2010-04-15|Infinite Power Solutions, Inc.|Environmentally-powered wireless sensor module|
    KR20120025521A|2009-05-20|2012-03-15|인피니트 파워 솔루션스, 인크.|Method of integrating electrochemical devices into and onto fixtures|
    EP2474056B1|2009-09-01|2016-05-04|Sapurast Research LLC|Printed circuit board with integrated thin film battery|
    CN102034063A|2009-09-28|2011-04-27|西门子（中国）有限公司|Method for adjusting continuous wave transmission time and reader|
    US20110090060A1|2009-10-16|2011-04-21|Tavshikar Milind M|Isolating RFID Reader|
    KR20110124042A|2010-05-10|2011-11-16|삼성테크윈 주식회사|Reader of rfid wherein phase noise is removed|
    EP2577777B1|2010-06-07|2016-12-28|Sapurast Research LLC|Rechargeable, high-density electrochemical device|
    US8760261B2|2010-06-11|2014-06-24|Intelleflex Corporation|Devices employing fast carrier cancellation and methods thereof|
    US9035774B2|2011-04-11|2015-05-19|Lone Star Ip Holdings, Lp|Interrogator and system employing the same|
    CA2818401C|2013-05-29|2020-10-20|Kapsch Trafficcom Ag|Adaptive echo cancellation for rfid systems|
    DE102014202865A1|2014-02-17|2015-08-20|Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.|Antenna device and method of operating the same|
    WO2016011421A1|2014-07-17|2016-01-21|The Regents Of The University Of California|Microwave reflector link, and cdma-spread spectrum reflector apparatus for reduction of unmodulated ambient blockers in reflected data links|
    US10591592B2|2015-06-15|2020-03-17|Humatics Corporation|High-precision time of flight measurement systems|
    US9660674B2|2015-07-16|2017-05-23|LGS Innovations LLC|Self-interference cancellation antenna systems and methods|
    CN108701896B|2015-12-17|2021-03-12|修麦提克斯公司|Device for realizing radio frequency positioning|
    US10452877B2|2016-12-16|2019-10-22|Assa Abloy Ab|Methods to combine and auto-configure wiegand and RS485|
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    优先权:
    申请号 | 申请日 | 专利标题
    US09/146,764|US6192222B1|1998-09-03|1998-09-03|Backscatter communication systems, interrogators, methods of communicating in a backscatter system, and backscatter communication methods|
    US09/757,763|US6600905B2|1998-09-03|2001-01-08|Communication system, interrogators and communication methods|US09/757,763| US6600905B2|1998-09-03|2001-01-08|Communication system, interrogators and communication methods|
    US11/193,992| USRE42751E1|1998-09-03|2005-07-29|Communication system, interrogators and communication methods|
    US12/643,948| USRE43242E1|1998-09-03|2009-12-21|Communication system, interrogators and communication methods|
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