JP4577245B2 - Wireless tag communication device - Google Patents

Description

  The present invention relates to an improvement in a wireless tag communication device that performs communication with a wireless tag capable of wirelessly writing and reading information.

  2. Description of the Related Art An RFID (Radio Frequency Identification) system is known in which information is read out in a non-contact manner by a predetermined wireless tag communication device (interrogator) from a small wireless tag (responder) in which predetermined information is stored. This RFID system is capable of reading information stored in a wireless tag by communication with the wireless tag communication device even when the wireless tag is dirty or disposed at an invisible position. Therefore, practical use is expected in various fields such as merchandise management and inspection processes.

  By the way, normally, the wireless tag communication device transmits a predetermined transmission signal (question wave) from the antenna toward the wireless tag, and a reply signal (response wave) returned from the wireless tag that has received the transmission signal. Is received by the antenna, and information is communicated with the wireless tag. However, a strong sneak signal (direct wave) from the transmission side is mixed in the received reply signal, increasing the overall received signal strength. There is a case. As a result, since the allowable input intensity of the amplifier is exceeded, the received signal cannot be sufficiently amplified, and as a result, the return signal component from the wireless tag cannot be sufficiently amplified. There was a problem that it decreased. Therefore, a technique for removing such a sneak signal from the transmission side has been proposed. For example, this is an interference compensation device for a mobile object identification device described in Patent Document 1.

JP-A-8-122429

  However, the removal of the sneak signal by the conventional technique as described above has a bad effect that it takes a relatively long time for the process in addition to not obtaining a sufficient removal accuracy. For this reason, there has been a demand for the development of a wireless tag communication device that can accurately remove a sneak signal from the transmission side in a short time.

  The present invention has been made in the background of the above circumstances, and an object of the present invention is to provide a wireless tag communication device capable of accurately removing a sneak signal from a transmission side in a short time.

  In order to achieve such an object, the gist of the present invention is that a transmission unit that transmits a predetermined transmission signal from an antenna toward a wireless tag, and a reply that is returned from the wireless tag according to the transmission signal A wireless tag communication device having a reception unit that communicates information with the wireless tag by receiving a signal through an antenna, and a reception memory unit that stores a reception signal received by the antenna; Stored in the reception memory unit, a carrier wave distribution unit that distributes the carrier wave of the transmission signal, a cancel signal output unit that controls the amplitude and / or phase of the carrier wave distributed by the carrier wave distribution unit and outputs it as a cancel signal The received signal is read, and the amplitude and / or phase of the cancel signal output from the cancel signal output unit based on the read received signal is determined. And a cancellation signal control unit for outputting a control signal for Gosuru, is characterized in that it has.

  According to this configuration, the reception memory unit that stores the reception signal received by the antenna, the carrier distribution unit that distributes the carrier wave of the transmission signal, and the amplitude and / or phase of the carrier wave distributed by the carrier distribution unit. The cancel signal output unit that controls the output of the cancel signal and the reception signal stored in the reception memory unit are read out, and the cancel signal output from the cancel signal output unit based on the read reception signal Since it has a cancel signal control unit that outputs a control signal for controlling the amplitude and / or phase, the time required for the sneak signal removal processing depends on the speed of the central processing unit, and the processing time is shortened. In addition to being able to do so, the removal accuracy of the sneak signal can be sufficiently enhanced. That is, it is possible to provide a wireless tag communication apparatus that can accurately remove a sneak signal from the transmission side in a short time.

  Here, preferably, a cancel memory unit for storing a cancel signal output from the cancel signal output unit is provided, and the cancel signal control unit reads the cancel signal stored in the cancel memory unit and reads the cancel signal. The amplitude and / or phase of the cancel signal output from the cancel signal output unit is controlled based on the output cancel signal. In this way, in addition to being able to suitably control the cancel signal, the cancel signal that has reached a steady state is stored in the cancel memory unit, so that when there is no change in the communication environment, the cancel signal is one by one. Therefore, the processing time can be shortened as much as possible.

  Preferably, the reception memory unit stores a reception signal sampled and converted into digital reception data, and the cancel memory unit stores a cancellation signal sampled and converted into digital cancellation data. The cancel signal control unit reads the digital reception data stored in the reception memory unit and the digital cancellation data stored in the cancellation memory unit, respectively, and performs predetermined processing based on the digital reception data and the digital cancellation data. The calculation is performed, and the amplitude and / or phase of the cancel signal output from the cancel signal output unit is controlled based on the calculation result. In this way, the amplitude and phase of the cancel signal can be determined as a result of the repetitive calculation by the central processing unit, and the time required for the wraparound signal removal process can be shortened in a practical manner.

  Preferably, the cancel signal control unit reads a reception signal stored in the reception memory unit, and adds a cancel signal output from the cancel signal output unit to the read reception signal. Based on this, the amplitude and / or phase of the cancel signal is controlled. In this way, the sneak signal included in the received signal can be suitably removed.

  Preferably, the cancellation signal control unit reads the reception signal stored in the reception memory unit, and adds the cancellation signal output from the cancellation signal output unit to the read reception signal, The amplitude and / or phase of the cancel signal is controlled so that the carrier wave component contained in the received signal is below a predetermined value. In this way, the sneak signal included in the received signal can be suitably removed in a practical manner.

  Preferably, the cancellation signal control unit reads the digital reception data stored in the reception memory unit and the digital cancellation data stored in the cancellation memory unit, respectively, and sums the digital reception data and the digital cancellation data. The weight for the amplitude and / or phase of the cancel signal is determined by adaptive calculation processing so that the value becomes equal to or less than a predetermined value, and the amplitude and / or phase of the cancel signal is controlled based on the weight. In this way, the amplitude and phase of the cancellation signal can be determined as a result of the adaptive calculation process repeated by the central processing unit, and the time required for the wraparound signal removal process can be shortened in a practical manner. .

  Preferably, a local signal output unit that outputs a local signal having a predetermined frequency, and a frequency conversion unit that multiplies the received signal by the local signal output by the local signal output unit to obtain an intermediate frequency signal. The reception memory unit stores the intermediate frequency signal converted by the frequency conversion unit. In this way, the cancel signal can be suitably controlled based on the intermediate frequency signal that is the down-converted received signal.

  Preferably, the variable amplification unit that amplifies the intermediate frequency signal converted by the frequency conversion unit, the A / D conversion unit that digitally converts the intermediate frequency signal output from the variable amplification unit, and the variable amplification And an amplification factor control unit that controls the amplification factor in the unit as much as possible within the limits allowed for the A / D conversion unit. In this way, the intermediate frequency signal can be amplified as much as possible.

  Preferably, the reception memory unit includes an orthogonal transform unit that converts the received signal into an I-phase signal and a Q-phase signal that are orthogonal to each other, and the reception memory unit includes the I-phase signal and the Q-phase converted by the orthogonal transform unit. The signal is stored. In this way, the cancellation signal can be suitably controlled based on the I-phase signal and Q-phase signal as a result of quadrature demodulation.

  Preferably, a variable amplification unit that amplifies the I-phase signal and the Q-phase signal respectively converted by the orthogonal transform unit, and an A-phase signal that is digitally converted from the I-phase signal and the Q-phase signal output from the variable amplification unit. A / D conversion unit, and an amplification factor control unit that controls the amplification factor in the variable amplification unit as much as possible within the limits allowed for the A / D conversion unit. In this way, the I-phase signal and Q-phase signal can be amplified as much as possible.

  Preferably, the transmission unit is capable of selectively transmitting a transmission signal including a command for performing information communication with the wireless tag and a carrier wave not including the command, The cancel signal control unit controls the amplitude and / or phase of the cancel signal during transmission of the transmission signal including the command. In this way, the cancel signal can be controlled prior to the substantial processing of the received signal, and the processing time can be shortened as much as possible.

  Preferably, the cancel signal control unit adaptively controls the amplitude and / or phase of the cancel signal based on a reception signal corresponding to a portion where a signal level in the transmission signal is a predetermined value or more. . In this way, the cancellation signal can be converged as quickly as possible by not using the reception signal corresponding to the portion where the signal level of the transmission signal is reduced in the adaptive control.

  Preferably, the transmission unit controls transmission end timing of the transmission signal according to convergence of the cancellation signal by adaptive control of the cancellation signal control unit. In this way, it is possible to perform substantial communication with the wireless tag while seeing the convergence of the cancellation signal.

  Preferably, the transmission unit stops transmission of a transmission signal including a command after the cancel signal has converged by adaptive control of the cancellation signal control unit, and transmits a carrier wave not including the command. In this way, the cancel signal can be controlled prior to the substantial processing of the received signal, and communication with the wireless tag can be reliably performed.

  Preferably, the amplifying unit for amplifying the received signal to which the cancel signal is added, a circuit switching unit for switching between a circuit through which the received signal passes through the amplifying unit and a circuit through which the received signal does not pass, and the cancel signal A circuit switching control unit that controls switching of the circuit by the circuit switching unit in accordance with the added received signal. In this way, the circuit can be switched so that the reception signal is amplified by the amplification unit when the sneak signal included in the reception signal is sufficiently removed.

  Preferably, the capacity of the reception memory unit is smaller than a size corresponding to a command included in the transmission signal. In this way, it is possible to store a sufficient received signal as required by the reception memory unit having as small a capacity as possible.

  Preferably, the capacity of the cancel memory unit is smaller than a size corresponding to a command included in the transmission signal. In this way, a sufficient cancel signal can be stored by using a cancel memory unit having a capacity as small as possible.

  Preferably, the reception memory unit is a two-stage buffer device having two storage areas. First, the reception signal is stored in one of the storage areas, and the other is stored when the storage area is saturated. The received signal is stored in the storage area. In this way, the time required for controlling the cancel signal can be reduced as much as possible by alternately using the two storage areas.

  Preferably, the cancel signal control unit reads a reception signal stored in the storage area when one storage area in the reception memory unit is saturated, and based on the read reception signal, It controls the amplitude and / or phase of the cancel signal output from the cancel signal output unit. In this way, the time required for controlling the cancel signal can be reduced as much as possible by alternately using the two storage areas.

  Preferably, the cancel memory unit is a two-stage buffer device having two storage areas, and a cancel signal output by a series of controls by the cancel signal control unit is first applied to one of the storage areas. The cancel signal that is stored and output by the next series of controls is stored in the other storage area. In this way, the time required for controlling the cancel signal can be reduced as much as possible by alternately using the two storage areas.

  Preferably, the cancel signal control unit reads a cancel signal stored in one storage area of the cancel memory unit, and is output from the cancel signal output unit based on the read cancel signal. The amplitude and / or phase of the cancel signal is controlled, and the controlled cancel signal is repeatedly stored in the cancel memory unit. In this way, the time required for controlling the cancel signal can be reduced as much as possible by alternately using the two storage areas.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a diagram for explaining a wireless tag communication system 10 in which the wireless tag communication device of the present invention is preferably used. The RFID tag communication system 10 includes an RFID tag communication device 12 according to an embodiment of the present invention, and a single or plural (single in FIG. 1) RFID tags 14 that are communication targets of the RFID tag communication device 12. It is a so-called RFID (Radio Frequency Identification) system, and the RFID tag communication device 12 functions as an interrogator of the RFID system, and the RFID tag 14 functions as a responder. That is, when the interrogation wave F _c (transmission signal) is transmitted from the radio tag communication device 12 toward the radio tag 14, a predetermined information signal (transmission data) is transmitted in the radio tag 14 that has received the interrogation wave F _c. The interrogation wave F _c is modulated by the above and is returned as a response wave F _r (reply signal) to the RFID tag communication apparatus 12, so that information is transmitted between the RFID tag communication apparatus 12 and the RFID tag 14. Communication is performed. The wireless tag communication system 10 is used, for example, for managing articles in a predetermined communication area. The wireless tag 14 is preferably attached to an article to be managed, for example. And are provided integrally.

FIG. 2 is a diagram illustrating the configuration of the wireless tag communication device 12. As shown in FIG. 2, the wireless tag communication device 12 generates a signal for transmission to the wireless tag 14 and processes a response wave returned from the wireless tag 14. ) And the like, and transmission processing for transmitting the interrogation wave F _c from the antenna 20 for transmission / reception to the wireless tag 14 based on the information signal supplied from the digital signal processing unit 16 The result of information communication between the radio tag 14 and the high frequency transmitter / receiver 18 that performs reception processing for receiving the response wave F _r returned from the radio tag 14 according to the interrogation wave F _c by the antenna 20 A database 22 provided in a storage device such as a hard disk for storage; a display unit 24 for displaying information relating to communication with the wireless tag 14; And a central control unit 26 that controls the operation of the RFID tag communication device 12 by controlling the digital signal processing unit 16, the high-frequency transmission / reception unit 18, the database 22, the display unit 24, and the like. ing.

  The digital signal processing unit 16 performs electronic processing based on a predetermined program stored in advance in a ROM that is a read-only memory while using a temporary storage function of a RAM that is a read / write memory by a CPU that is a central processing unit. A so-called computer that processes and controls information, a command bit string generation unit 30 that generates a command bit string corresponding to transmission data to the wireless tag 14, and a pulse width modulation of a digital signal output from the command bit string generation unit 30 For storing the modulation signal modulated by the AM modulation unit 34, the AM modulation unit 34 for modulating the signal encoded by the encoding unit 32 by the AM method, and the like. Included in the received signal received by the antenna 20 via the transmission memory unit 36 and the high frequency transmission / reception unit 18 An adaptive cancel control unit 38 which is a cancel signal control unit for controlling a cancel signal for removing a sneak signal from the transmitting side, and a cancel memory unit for storing the cancel signal supplied from the high frequency transmitting / receiving unit 18 40, a reception memory unit 42 for storing the reception signal supplied from the high-frequency transmission / reception unit 18, and an AM demodulation for detecting an AM demodulated wave by demodulating the reception signal read from the reception memory unit 42 by the AM method Section 44, a decoding section 46 for decoding the AM demodulated wave demodulated by the AM demodulation section 44 by the FSK method or the like, and information relating to the modulation of the wireless tag 14 by interpreting the decoded signal decoded by the decoding section 46 A response bit string interpretation unit 48 for reading out the signal.

The central control unit 26 uses electronic information based on a predetermined program stored in advance in a ROM that is a read-only memory while using a temporary storage function of a RAM that is a read / write memory by a CPU that is a central processing unit. A so-called computer that processes and controls the command bit string generation unit 30, the encoding unit 32, the AM modulation unit 34, the high frequency transmission / reception unit 18 and the like, thereby interrogating the interrogation wave toward the wireless tag 14. a transmission control unit 50 for controlling the transmission processing of F _c, of the return signal from the high-frequency transceiver 18, AM demodulating portion 44, the wireless tag 14 by controlling the decoding unit 46, and the reply bit string interpreting portion 48 or the like a reception control unit 52 for controlling the reception processing, the amplification factor G _IFi in the variable amplification section 92 of the high-frequency transceiver 18, the reception signal a / D converter 94 An amplification factor control unit 54 that controls as much as possible within the allowable limit (a limit that does not saturate), and a circuit switching control unit 56 that controls switching of circuits by the circuit switching unit 84 of the high-frequency transmitting / receiving unit 18 are provided. ing. The circuit switching control unit 56 preferably controls the circuit switching by the circuit switching unit 84 in accordance with the reception signal to which the cancel signal is added in the cancel signal synthesis unit 66 in the high frequency transmission / reception unit 18 described later. That is, the circuit is switched so that the reception signal is amplified by the reception signal amplification unit 82 described later when the sneak signal included in the reception signal is sufficiently removed.

FIG. 3 is a block diagram illustrating in detail the configuration of the high-frequency transmitter / receiver 18. As shown in FIG. 3, the high-frequency transmitter / receiver 18 outputs a carrier wave output unit 58 that outputs the carrier wave (excitation signal) of the interrogation wave F _c , and a carrier wave that distributes the carrier wave output by the carrier wave output unit 58. a distribution unit 60, a power amplifier 62 for transmission from the antenna 20 put the transmission data (command signal) to be read from the carrier distribution unit 60 the transmission memory unit 36 to the distributed carrier by the interrogating wave F _c A transmission / reception separating unit 64 that supplies a transmission signal input from the power amplifier 62 to the antenna 20 and supplies a reception signal received by the antenna 20 to a cancel signal combining unit 66. In the present embodiment, the command bit string generation unit 30, the encoding unit 32, the AM modulation unit 34, the carrier wave output unit 58, the power amplifier 62, and the like transmit a transmission signal from the antenna 20 toward the wireless tag 14. It corresponds to. In addition, by controlling the presence / absence of command output from the command bit string generation unit 30, a transmission signal including a command for communicating information with the wireless tag 14 and a carrier wave not including the command are transmitted. It can be transmitted selectively.

  The high frequency transmitter / receiver 18 also includes a cancel phase control signal D / A converter 68 for analog conversion of the cancel phase control signal θC ′ input from the adaptive cancel controller 38, and its cancel phase control signal D / A conversion. A cancellation phase control signal amplification unit 70 that amplifies the cancellation phase control signal analog-converted by the unit 68, and is distributed by the carrier distribution unit 60 according to the cancellation phase control signal amplified by the cancellation phase control signal amplification unit 70. A cancel phase control unit 72 functioning as a cancel phase shifter for controlling the phase of the carrier wave, and a cancel amplitude control signal D / A conversion unit for analog converting the cancel amplitude control signal AC ′ input from the adaptive cancel control unit 38 74 and its cancel amplitude control signal A cancellation amplitude control signal amplifying unit 76 that amplifies the cancellation amplitude control signal analog-converted by the A / A conversion unit 74, and the cancellation phase control unit according to the cancellation amplitude control signal amplified by the cancellation amplitude control signal amplification unit 76 A cancel amplitude control unit 78 that functions as a cancel amplifier that controls the amplitude of the phase-controlled carrier wave output from 72 and outputs it as a cancel signal, and a cancel signal that distributes the cancel signal output from the cancel amplitude control unit 78 And a distribution unit 80. In this embodiment, the cancel phase control unit 72 and the cancel amplitude control unit 78 correspond to a cancel signal output unit that controls the amplitude and / or phase of the carrier wave distributed by the carrier wave distribution unit 60 and outputs it as a cancel signal. .

The high-frequency transmitter / receiver 18 synthesizes (adds) the cancel signal distributed by the cancel signal distributor 80 and the received signal supplied from the transmission / reception separator 64, and the cancel signal. A reception signal amplification unit 82 that amplifies the reception signal added with the cancel signal output from the synthesis unit 66, and a circuit through which the reception signal output from the cancellation signal synthesis unit 66 passes through the reception signal amplification unit 82. A circuit switching unit 84 for switching the circuit to not perform, a local signal output unit 86 for outputting a predetermined local signal, and a local signal output unit 86 for the reception signal output from the cancel signal synthesis unit 66 or the reception signal amplification unit 82. The received signal frequency converter 88 that multiplies the local signal output by Received signal BPF (Band Pass Filter) 90 that passes only a signal in a predetermined frequency band among the intermediate frequency signals output from number converter 88, and a variable gain that amplifies the intermediate frequency signal output from received signal BPF 90 A variable amplification unit 92 that is an amplifier, and a received signal A / D conversion unit 94 that digitally converts an intermediate frequency signal amplified by the variable amplification unit 92 and stores the digital signal in the reception memory unit 42 are provided. That is, the reception memory unit 42 stores the reception signal sampled by the reception signal A / D conversion unit 94 and converted into digital reception data. Here, the circuit in the circuit switching unit 84 is controlled to be switched by the circuit switching control unit 56. The amplification factor _GIFi of the variable amplification unit 92 is controlled by the amplification factor control unit 54. In this embodiment, the cancel signal synthesizer 66, the received signal amplifying unit 82, the circuit switching unit 84, the received signal frequency converting unit 88, the variable amplifying unit 92, and the like send a reply signal returned from the wireless tag 14 to the antenna 20. It is equivalent to the receiving part which communicates information between the radio | wireless tags 14 by receiving by (3).

  The high frequency transmitter / receiver 18 multiplies the cancel signal distributed by the cancel signal distributor 80 by the local signal output by the local signal output unit 86 to perform frequency conversion, and a cancel signal frequency converter 96 A cancel signal BPF 98 that passes only a signal in a predetermined frequency band among the cancel signals output from the cancel signal frequency converter 96, a cancel signal amplifier 100 that amplifies the cancel signal output from the cancel signal BPF 98, and A cancel signal A / D conversion unit 102 that digitally converts the cancel signal amplified by the cancel signal amplification unit 100 and stores the digital signal in the cancel memory unit 40; That is, the cancel memory unit 40 stores a reception signal sampled by the cancel signal A / D conversion unit 102 and converted into digital cancel data.

  FIG. 4 is a diagram illustrating a configuration of a buffer device that is preferably used as the cancel memory unit 40 or the reception memory unit 42. In the present embodiment, both the cancel memory unit 40 and the reception memory unit 42 have the same configuration as shown in FIG. 4, and preferably have a two-stage configuration including two storage areas BUF0 and BUF1. It is a circular buffer. That is, input information (input data) is first stored in BUF0 which is one of the storage areas, and is stored in BUF1 which is the other storage area when the storage area is saturated. Each of these two storage areas BUF0 and BUF1 has a capacity corresponding to N samples of the transmission signal, and each capacity is smaller than a size corresponding to a command included in the transmission signal.

FIG. 5 is a block diagram illustrating in detail the configuration of the adaptive cancel control unit 38. As shown in FIG. 5, the adaptive cancel control unit 38 includes a cancel input data correction unit 104 that corrects a cancel signal read from the cancel memory unit 40, and a correction that is output from the cancel input data correction unit 104. Canceled complex signal generation unit 106 that generates complex signal XC from the canceled signal, input data correction unit 108 that corrects the received signal read from reception memory unit 42, and the correction that is output from input data correction unit 108 Based on the complex signal generator 110 that generates the complex signal XI from the received signal, the complex signal XC input from the cancel complex signal generator 106, and the complex signal XI input from the complex signal generator 110, the cancel weight Multiplication unit 114 and output data synthesis unit 116 The adaptive arithmetic unit 112 which performs adaptive control to converge the cancellation weights through a cancellation weight initial value buffer 118 for storing the cancellation weights WC _CONV calculated by the adaptive arithmetic unit 112, the based on the cancellation weights WC _CONV A cancel weight for outputting a cancel phase control signal θC ′ for controlling the amount of phase shift in the cancel phase control unit 72 of the high frequency transmitting / receiving unit 18 and a cancel amplitude control signal AC ′ for controlling the amplification factor in the cancel amplitude control unit 78. The conversion part 120 is provided.

FIG. 6 is a diagram for explaining the configuration of the cancellation weight initial value buffer 118. As shown in FIG. 6, the cancellation weight initial value buffer 118 is a two-stage buffer device having two storage areas WC _DEF BUF0 and WC _DEF BUF1, and the cancellation weight calculated by the adaptive calculation unit 112. WC _CONV is alternately stored in these two storage areas WC _DEF BUF0 and WC _DEF BUF1. Here, as will be described later, the adaptive calculation unit 112 performs adaptive control based on information stored in the two storage areas BUF0 and BUF1 in the cancel memory unit 40 and the reception memory unit 42, respectively. The value of the WC after adaptive processing based on the contents stored in the BUF0 in each of the cancel memory unit 40 and the reception memory unit 42 is stored in the storage area WC _DEF BUF0 of the cancel weight initial value buffer 118, and the cancel memory unit 40 and The value of WC after adaptive processing based on the stored contents of BUF1 in each of the reception memory units 42 is stored in the storage area WC _DEF BUF1 of the cancel weight initial value buffer 118, respectively. In this embodiment, the initial values of the two storage areas WC _DEF BUF0 and WC _DEF BUF1 are both 1 + j0.

Specifically, the cancel input data correction unit 104 performs correction for canceling amplification in the high-frequency transmission / reception unit 18 of a cancel signal read from the cancel memory unit 40. That is, when the amplification factor in the cancellation signal amplification unit 100 of the high-frequency transmission / reception unit 18 is G _IFc , the value is corrected by dividing the cancellation signal read from the cancellation memory unit 40 by the amplification factor G _IFc. To do. Further, the cancellation complex signal generation unit 106 generates a signal whose phase is delayed by 90 ° by, for example, Hilbert transform based on the cancellation signal output from the cancellation input data correction unit 104, and the complex corresponding to the cancellation signal. The signal XC is supplied to the adaptive calculation unit 112 and the cancel weight multiplication unit 114. When the sampling rate of the cancel signal A / D converter 102 is 4n times the frequency of the cancel signal frequency-converted by the cancel signal frequency converter 96, the signal before n samples is used as the imaginary part. May be.

Specifically, the input data correction unit 108 performs correction for eliminating amplification in the high-frequency transmission / reception unit 18 of the reception signal read from the reception memory unit 42. That is, the amplification factor in the reception signal amplification unit 82 of the high-frequency transmission / reception unit 18 is _GLNA (G _LNA = 1 when not passing through the reception signal amplification unit 82), and the amplification factor in the variable amplification unit 92 is _GIFi . in some cases, the received signal read from the reception memory section 42 is divided by the product G _LNA × G _IFi their gain, subtracting the further cancellation signal corrected by the cancel input data correcting unit 104 therefrom To obtain the value of only the received signal. In the configuration shown in FIG. 3, a switch may be provided between the cancel signal distribution unit 80 and the cancel signal synthesis unit 66 so that only the received signal can be stored in the reception memory unit 42 as necessary. . Further, the complex signal generation unit 110 generates a signal whose phase is delayed by 90 ° by, for example, Hilbert transform based on the reception signal output from the input data correction unit 108, and the complex signal XI corresponding to the reception signal. To the adaptive calculation unit 112 and the output data synthesis unit 116. When the sampling rate of the reception signal A / D conversion unit 94 is 4n times the frequency of the reception signal frequency-converted by the reception signal frequency conversion unit 88, that is, the intermediate frequency signal, the signal n samples before is It may be used as an imaginary part.

  Specifically, the adaptive calculation unit 112 is based on the complex signal XC input from the cancel complex signal generation unit 106 and the complex signal XI input from the complex signal generation unit 110, and a well-known LMS algorithm or the like. The cancel weight WC is adaptively controlled using the weight update recurrence formula. In this adaptive control, the cancellation weight multiplication unit 114 multiplies a cancellation signal (complex signal) output from the cancellation complex signal generation unit 106 by a predetermined cancellation weight WC, and the output data synthesis unit 116 generates the complex signal. The received signal (complex signal) output from unit 110 and the weight multiplied cancellation signal (complex signal) output from cancellation weight multiplication unit 114 are added to calculate output data Y. The adaptive calculation unit 112 converges the cancel weight WC so that the output data Y output from the output data synthesis unit 116 is smaller than a predetermined value and further as small as possible.

Specifically, the cancellation weight conversion unit 120 firstly cancels the WC _CONV converged by the calculation of the adaptive calculation unit 112 and the cancellation phase control unit 72 when the reception signal is stored in the reception memory unit 42. and cancellation corresponding to the set value of the amplitude control section 78 adds the cancellation weights WC _DEF, canceling the phase control unit 72 and the cancel weights for updating the setting of the cancel the amplitude controller _{78 WC sET (= WC CONV +} WC DEF) Is calculated. Next, the cancel weight WC _SET is converted into the cancel phase shift control signal θC ′ and the cancel amplitude control signal AC ′. When WC _SET = WC _SET r + jWC _SET i, the phase θC of the cancel signal controlled by the cancel phase control unit 72 and the amplitude AC of the cancel signal controlled by the cancel amplitude control unit 78 are, for example, (1) , (2). However, the phase θC is determined in the quadrant using the signs of WC _SET r and jWC _SET i, and is within the numerical range of the following equation (3). The cancel phase θC ′ and the cancel amplitude control signal AC ′ are obtained by converting the cancel phase θC and the cancel amplitude AC obtained in this way using a predetermined conversion table.

θC = tan ⁻¹ (WC _SET r / jWC _SET i) (1)

AC = (WC _SET r ² + jWC _SET i ² ) ^1/2 (2)

  −π <θC ≦ π (3)

FIG. 7 is a view for explaining the configuration of the RFID circuit element 122 provided in the RFID tag 14. As shown in FIG. 7, the RFID circuit element 122 has an antenna 124 for communicating with the RFID tag communication device 12, and is connected to the antenna 124 from the RFID tag communication device 12. And an IC circuit unit 126 for processing the transmission signal. The IC circuit unit 126 rectifies the interrogation wave F _c received from the antenna 124 from the RFID tag communication apparatus 12 and stores the energy of the interrogation wave F _c rectified by the rectification unit 128. Power supply unit 130, a clock extraction unit 132 that extracts a clock signal from a carrier wave received by the antenna 124 and supplies the clock signal to the control unit 138, and a memory unit that functions as a storage unit that can store a predetermined information signal 134, a modulation / demodulation unit 136 that is connected to the antenna 124 and modulates and demodulates a signal, and controls the operation of the RFID circuit element 122 through the rectification unit 128, the clock extraction unit 132, the modulation / demodulation unit 136, and the like. And a control unit 138 for functionally. The control unit 138 performs control for storing the predetermined information in the memory unit 134 by communicating with the RFID tag communication device 12, and the modulation / demodulation unit 136 receives the interrogation wave F _c received by the antenna 124. executes basic control such as control that reflects back from the antenna 124 as a response wave F _r in terms of modulated based on the information signal stored in the memory unit 134.

FIG. 8 is a timing chart for explaining the adaptive control of the cancel weight by the adaptive cancel control unit 38. As shown in FIG. 8, in communication with the wireless tag 14, first, the command bit string generation unit 30, the encoding unit 32, the AM modulation unit 34, and the high frequency transmission / reception unit 18 of the digital signal processing unit 16. carrier output unit 58, the carrier distribution unit 60, and outputs the transmission signal including a command for communicating information between said wireless tag 14 by the power amplifier 62 and the like, transmitted as interrogating wave F _c from the antenna 20 Is done. A sneak signal (sneak wave) from the transmission side is generated in the transmission / reception separation unit 64 and the antenna 20 substantially in synchronization with this transmission operation, and is stored in the storage area BUF0 of the reception memory unit 42, and the reception process thereof The cancel signal used in the above is stored in the storage area BUF0 of the cancel memory unit 40.

Subsequently, the storage of the reception signal and the cancel signal in the storage area BUF1 is started when the writing to the storage area BUF0 is completed, that is, when the BUF0 is saturated. Further, when the writing to the storage area BUF0 is completed, the reception signal and the cancellation signal stored in the BUF0 are read out, and the adaptive control of the cancellation signal based on the reception signal and the cancellation signal is performed by the adaptive cancellation control unit 38. The cancel weight WC _CONV converged by the adaptive control is stored in the storage area WC _DEF BUF0 of the cancel weight initial value buffer 118. That is, an adaptive cancel process based on information stored in the other storage area BUF0 is performed during writing to the storage area BUF1 in the cancel memory section 40 and the reception memory section 42. As shown in FIG. 8, the transmission signal includes a portion where the signal level is relatively high and a portion where the signal level is relatively low due to AM modulation. However, the adaptive cancel control unit 38 preferably uses the transmission signal. The cancel weight is adaptively processed based on a received signal corresponding to a portion having a relatively high signal level, that is, a portion having a signal level equal to or higher than a predetermined value. Above, cancellation weights WC _CONV converged in the storage area WC _DEF BUF0 of the cancellation weight initial value buffer 118 is stored by a series of processes shown in [1] in FIG. 8, the cancellation weight WC _CONV by the cancellation weight conversion section 120 The cancel phase control signal θC ′ and the cancel amplitude control signal AC ′ based on the above are output, and the settings of the cancel phase control unit 72 and the cancel amplitude control unit 78 are updated.

Subsequently, the storage of the reception signal and the cancel signal in the storage area BUF0 is started when the writing to the storage area BUF1 is completed, that is, when the BUF1 is saturated. At this time, the received signal and the cancel signal stored in the storage area BUF0 are deleted or overwritten with new information. Further, when the writing to the storage area BUF1 is completed, the reception signal and the cancellation signal stored in the BUF1 are read out, and the adaptive control of the cancellation signal based on the reception signal and the cancellation signal is performed by the adaptive cancellation control unit 38. The cancel weight WC _CONV converged by the adaptive control is stored in the storage area WC _DEF BUF1 of the cancel weight initial value buffer 118. That is, an adaptive cancel process based on information stored in the other storage area BUF1 is performed during writing to the storage area BUF0 in the cancel memory section 40 and the reception memory section 42. Above, cancellation weights WC _CONV converged in the storage area WC _DEF BUF1 of the cancellation weight initial value buffer 118 is stored by a series of processes shown in [2] in FIG. 8, the cancellation weight WC _CONV by the cancellation weight conversion section 120 The cancel phase control signal θC ′ and the cancel amplitude control signal AC ′ based on the above are output, and the settings of the cancel phase control unit 72 and the cancel amplitude control unit 78 are updated. Then, the processing similar to the series of processes indicated by [1] and [2] in FIG. 8 described above, that is, the series of processes indicated by [3] and [4] in FIG. The cancellation weight WC for determining the value is optimized.

Subsequently, transmission of a carrier wave not including a command is started when the command phase ends. In such transmission, command generation by the command bit string generation unit 30 of the digital signal processing unit 16 is not executed, and in other words, a carrier on which no command is placed by the carrier output unit 58 and the power amplifier 62 of the high-frequency transmission / reception unit 18, in other words For example, a carrier wave for carrying a reply signal from the wireless tag 14 is transmitted from the antenna 14. Thereafter, as shown in the tag response phase of FIG. 8, the response wave F _r from the wireless tag 14 and the sneak signal from the transmission side are received by the antenna 20. Envelope tag response phase of FIG. 8 correspond to the response wave F _r from the wireless tag 14, the response wave F _r from the wireless tag 14 is very weak compared to the echo signal from the transmission side For this reason, when the sneak signal cannot be sufficiently removed, the signal received by the antenna 20 is almost the same as the sneak signal. In this embodiment, since the reception of the response wave F _r is started when the cancellation weight WC has sufficiently converged, the signal-to-noise ratio can be suitably read from the reply signal from the wireless tag 14. Excellent communication can be realized.

  FIG. 9 is a flowchart for explaining a main part of search control of the wireless tag 14 through the digital signal processing unit 16 and the high frequency transmission / reception unit 18 by the central control unit 26 of the wireless tag communication device 12. It is repeatedly executed at a predetermined cycle.

First, in a step (hereinafter, step is omitted) S1 corresponding to the operation of the transmission control unit 50 and the reception control unit 52, an instruction for transmitting a transmission signal including a predetermined command is sent to the wireless tag 14. In addition to being output to the digital signal processing unit 16 and the high frequency transmission / reception unit 18, a reception instruction for processing a reception signal received by the antenna 20 is output to the digital signal processing unit 16 and the high frequency transmission / reception unit 18. Next, in S2, it is determined whether received data for N samples has been taken into the reception memory unit 42 or not. While the determination of S2 is denied, the determination is repeated to wait, but when the determination of S2 is affirmed, after SA is executed in S3, S3 is executed. Then, it is determined whether or not the amplification factor _GIFi of the variable amplification unit 92 (IF amplifier) of the high-frequency transmission / reception unit 18 is _{equal to} or greater than a predetermined value _GIFmax . If the determination in S3 is affirmative, in S4, the circuit switching unit 84 in the high-frequency transmission / reception unit 18 is switched to a circuit that passes through the reception signal amplification unit 82, and then the processing in S7 and subsequent steps is executed. However, if the determination in S3 is negative, it is determined in S5 whether or not the amplification factor _GIFi of the variable amplification unit 92 of the high-frequency transmission / reception unit 18 is equal to or less than a predetermined value _GIFmin . If the determination in S5 is affirmative, in S6, the circuit switching unit 84 in the high-frequency transmitting / receiving unit 18 is switched to a circuit that does not pass through the reception signal amplifying unit 82, and then the processing in S7 and subsequent steps is executed. However, if the determination in S5 is negative, it is determined in S7 whether or not all reply signals (response data) from the wireless tag 14 have been received. If the determination in S7 is negative, the processing from S2 onward is executed again, but if the determination in S7 is positive, in S8, the AM demodulation unit 44 of the digital signal processing unit 16 is used. The received signal stored in the reception memory unit 42 is demodulated, and the search result of the wireless tag 14 is obtained through the decoding unit 46, the response bit string interpretation unit 48, and the like. In S9, the search result of the wireless tag 14 obtained in S8 is displayed on the display unit 24, and then this routine is terminated. In the above control, S3 to S6 correspond to the operation of the circuit switching control unit 56.

FIG. 10 is a flowchart for explaining a main part of adaptive cancel control which is a part of the RFID tag search control shown in FIG. In this control, first, in SA1, the cancel signal (cancel input data) stored in the cancel memory unit 40 and the received signal (input data) stored in the reception memory unit 42 are read. Next, in SA2 corresponding to the operations of the cancel input data correcting unit 104 and the input data correcting unit 108, the level of the cancel signal read from the cancel memory unit 40 is the cancel signal amplifying unit of the high frequency transmitting / receiving unit 18. It is corrected based on the amplification factor G _IFc at 100. The level of the received signal read from the reception memory section 40 is corrected based on the gain G _IFi in gain G _LNA and the variable amplification section 92 in the reception signal amplifier 82 of the high-frequency transceiver 18 . Next, in SA3 corresponding to the operations of the cancellation complex signal generation unit 106 and the complex signal generation unit 110, corresponding complex signals XC and XI are generated from the cancellation signal and the reception signal corrected in SA2. Next, at SA4, the cancellation weight WC is multiplied by the complex signal XC corresponding to the cancellation signal via the cancellation weight multiplication unit 114, and the cancellation data thus multiplied by the cancellation weight WC is the output data synthesis unit. At 116, a composite output Y is obtained by adding to the complex signal XI corresponding to the received signal. Next, in SA5, the difference between the error signal, that is, a predetermined reference signal (this reference signal is preferably zero) and the composite output Y calculated in SA4 is obtained. Next, in SA6, the cancellation weight WC is updated based on a well-known recurrence formula for updating the cancellation weight, such as LMS, in accordance with the error signal calculated in SA5.

Next, in SA7, it is determined whether or not the cancel weight WC has converged. If the determination at SA7 is affirmative, the processing below SA10 is executed, but if the determination at SA7 is negative, a predetermined time has elapsed since the start of adaptive cancellation processing at SA8. It is determined whether or not. When the determination at SA8 is negative, the processing after SA1 is executed again. When the determination at SA8 is positive, a predetermined warning (warning) video is displayed on the display unit 24 at SA9. After the display, the canceled cancellation weight WC _CONV is stored in the cancellation weight initial value buffer 118 in SA10. Next, in SA11, a value WC _DEF corresponding to the cancellation weight WC _CONV stored in SA10 is added, and the settings of the cancellation phase control unit 72 and the cancellation amplitude control unit 78 of the high frequency transmission / reception unit 18 are updated. A set value WC _SET is obtained. Next, in the above cancellation weight conversion unit SA12 corresponding to the operation of the 120, on the basis of the set value WC _SET calculated in SA11, cancel the phase control signal for setting the phase shift amount in the cancellation phase controller 72 A cancel amplitude control signal AC ′ for setting the amplification factor in θC ′ and the cancel amplitude controller 78 is output. Then, in SA13 corresponding to the operation of the amplification factor control unit 54, the _limit that the amplification factor G _IFi of the variable amplification unit 92 is allowed to the received signal A / D conversion unit 94 based on the converged cancellation weight WC _CONV. In FIG. 9, the RFID tag search control shown in FIG. 9 is resumed. In the above control, SA1 to SA8 and SA10 to SA12 correspond to the operation of the adaptive cancel control unit 38.

  As described above, according to the present embodiment, the reception memory unit 42 that stores the reception signal received by the antenna 20, the carrier distribution unit 60 that distributes the carrier wave of the transmission signal, and the carrier distribution unit 60 distribute the carrier signal. The cancel phase control unit 72 and cancel amplitude control unit 78, which are cancel signal output units that control the amplitude and / or phase of the carrier wave to be output and output as a cancel signal, and the reception signal stored in the reception memory unit 42 are read out A cancel phase control signal which is a control signal for controlling the amplitude and / or phase of the cancel signal output via the cancel phase control unit 72 and the cancel amplitude control unit 78 based on the read reception signal. An adaptive signal which is a cancel signal controller that outputs θC ′ and a cancel amplitude control signal AC ′. Since the cell control unit 38 (SA1 to SA8 and SA10 to SA12) is included, the time required for the wraparound signal removal processing depends on the speed of the digital signal processing unit 16, and the processing time can be shortened. In addition, the removal accuracy of the sneak signal can be sufficiently increased. That is, it is possible to provide the RFID tag communication apparatus 12 that can accurately remove the sneak signal from the transmission side in a short time.

  The cancel memory unit 40 stores a cancel signal output via the cancel phase control unit 72 and the cancel amplitude control unit 78, and the adaptive cancel control unit 38 is stored in the cancel memory unit 40. Since the cancel signal is read and the amplitude and / or phase of the cancel signal output via the cancel phase control unit 72 and the cancel amplitude control unit 78 is controlled based on the read cancel signal, In addition to being able to suitably control the cancel signal, it is necessary to store the cancel signal that has reached a steady state in the cancel memory unit 40, and to control the cancel signal one by one when there is no change in the communication environment. The processing time can be reduced as much as possible.

  The reception memory unit 42 stores a reception signal sampled by the reception signal A / D conversion unit 94 into digital reception data. The cancellation memory unit 40 includes the cancellation signal A / D. The cancel signal sampled by the conversion unit 102 and converted into digital cancel data is stored. The adaptive cancel control unit 38 stores the digital reception data stored in the reception memory unit 42 and the cancel memory unit 40. The digital cancellation data is read out, a predetermined calculation is performed based on the digital reception data and the digital cancellation data, and the cancellation is output via the cancellation phase control unit 72 and the cancellation amplitude control unit 78 based on the calculation result. Signal amplitude and Because it controls the phase, the amplitude and phase of the cancellation signal can be determined as a result of the repetitive calculation by the digital signal processing unit 16, and the time required for the removal process of the wraparound signal can be shortened in a practical manner. can do.

  The adaptive cancel control unit 38 reads the reception signal stored in the reception memory unit 42, and outputs the read reception signal via the cancel phase control unit 72 and the cancel amplitude control unit 78. Since the amplitude and / or phase of the cancellation signal is controlled based on the result of adding the cancellation signal, the sneak signal included in the reception signal can be suitably removed.

  The adaptive cancel control unit 38 reads the reception signal stored in the reception memory unit 42, and outputs the read reception signal via the cancel phase control unit 72 and the cancel amplitude control unit 78. As the result of adding the cancel signal, the amplitude and / or phase of the cancel signal is controlled so that the carrier component included in the received signal is less than or equal to a predetermined value. Can be suitably removed in a typical manner.

  The adaptive cancel control unit 38 reads the digital reception data stored in the reception memory unit 42 and the digital cancellation data stored in the cancellation memory unit 40, respectively, and the sum of the digital reception data and the digital cancellation data is calculated. Since the weight with respect to the amplitude and / or phase of the cancel signal is determined by adaptive arithmetic processing so as to be equal to or less than a predetermined value, and the amplitude and / or phase of the cancel signal is controlled based on the weight, the digital signal The amplitude and phase of the cancel signal can be determined as a result of the adaptive calculation process repeated by the processing unit 16, and the time required for the wraparound signal removal process can be shortened in a practical manner.

  Further, a local signal output unit 86 that outputs a local signal having a predetermined frequency, and a received signal frequency conversion unit 88 that multiplies the received signal by the local signal output by the local signal output unit 86 to obtain an intermediate frequency signal. Since the reception memory unit 42 stores the intermediate frequency signal converted by the reception signal frequency conversion unit 88, the reception memory unit 42 stores the intermediate frequency signal based on the intermediate frequency signal that is the down-converted reception signal. The cancel signal can be suitably controlled.

Further, a variable amplification unit 92 that amplifies the intermediate frequency signal converted by the reception signal frequency conversion unit 88, and a reception signal A / D conversion unit 94 that digitally converts the intermediate frequency signal output from the variable amplification unit 92; And an amplification factor control unit 54 (SA13) for controlling the amplification factor G _IFi in the variable amplification unit 92 as much as possible within the limit allowed by the reception signal A / D conversion unit 94. Therefore, the intermediate frequency signal can be amplified as much as possible.

  The transmission control unit 50 (S1) is configured to selectively transmit a transmission signal including a command for communicating information with the wireless tag 14 and a carrier wave not including the command. The signal processing unit 16 and the high frequency transmission / reception unit 18 can be controlled, and the adaptive cancellation control unit 38 controls the amplitude and / or phase of the cancellation signal during transmission of the transmission signal including the command. Therefore, the cancel signal can be controlled prior to the substantial reception signal processing, and the processing time can be shortened as much as possible.

  Further, the adaptive cancellation control unit 38 adaptively controls the amplitude and / or phase of the cancellation signal based on a reception signal corresponding to a portion where the signal level in the transmission signal is a predetermined value or more. The cancellation signal can be converged as quickly as possible by not using the reception signal corresponding to the portion where the signal level of the transmission signal is lowered for adaptive control.

  A reception signal amplifying unit 82 for amplifying the reception signal to which the cancel signal is added; a circuit switching unit 84 for switching between a circuit through which the reception signal passes through the reception signal amplification unit 82 and a circuit through which the reception signal does not pass through; Since it has a circuit switching control unit 56 (S3 to S6) for controlling switching of the circuit by the circuit switching unit 84 in accordance with the received signal to which the cancel signal is added, the sneak signal included in the received signal When the signal is sufficiently removed, the circuit can be switched so that the received signal is amplified by the received signal amplifier 82.

  Further, since the capacity of the reception memory unit 42 is smaller than the size corresponding to the command included in the transmission signal, the reception memory unit 42 having as small a capacity as possible stores sufficient reception signals. it can.

  Further, since the capacity of the cancel memory unit 40 is smaller than the size corresponding to the command included in the transmission signal, the cancel memory unit 40 having as small a capacity as possible stores a sufficient cancel signal. it can.

  The reception memory unit 42 is a two-stage buffer device having two storage areas BUF0 and BUF1. First, the reception signal is stored in one of the storage areas, and the other is stored when the storage area is saturated. Since the received signal is stored in the storage area, the time required to control the cancel signal can be shortened as much as possible by alternately using the two storage areas BUF0 and BUF1.

  Further, the adaptive cancel control unit 38 reads a reception signal stored in the storage area when one storage area in the reception memory unit 42 is saturated, and the cancel phase is based on the read reception signal. Since the amplitude and / or phase of the cancel signal output via the control unit 72 and the cancel amplitude control unit 78 are controlled, the two storage areas BUF0 and BUF1 are used alternately to The time required for control can be reduced as much as possible.

  The cancel memory unit 40 is a two-stage buffer device having two storage areas BUF0 and BUF1, and a cancel signal output by a series of controls by the adaptive cancel control unit 38 is first sent to one of the storage areas. Since the cancel signal output by the next series of control is stored in the other storage area, the two storage areas BUF0 and BUF1 are alternately used to control the cancel signal. Time can be reduced as much as possible.

  The adaptive cancel control unit 38 reads a cancel signal stored in one storage area in the cancel memory unit 40, and the cancel phase control unit 72 and the cancel amplitude control unit based on the read cancel signal. 78, the amplitude and / or phase of the cancel signal output via 78 is controlled, and the controlled cancel signal is repeatedly stored in the cancel memory unit 40. Therefore, the two storage areas BUF0 and BUF1 are By using them alternately, the time required for controlling the cancel signal can be shortened as much as possible. As described above, since the convergence calculation of the phase and amplitude of the cancel signal is executed when writing to the other storage area is performed, a cancel signal reflecting the result of the convergence calculation is written. Is a storage area from which a signal is read for the convergence calculation.

  Next, another preferred embodiment of the present invention will be described in detail with reference to the drawings. In the following description, parts common to the above-described embodiments are denoted by the same reference numerals and description thereof is omitted.

  FIG. 11 is a diagram for explaining the configuration of an RFID tag communication apparatus 140 that is another preferred embodiment of the present invention and is preferably applied to the RFID tag communication system 10 of FIG. As shown in FIG. 11, the digital signal processor 16 provided in the RFID tag communication apparatus 140 of this embodiment does not include the AM demodulator 44. Instead, an orthogonal demodulator described in detail below. Is provided in the high-frequency transceiver 142.

  FIG. 12 is a diagram for explaining in detail the configuration of the high-frequency transmission / reception unit 142 provided in the RFID tag communication apparatus 140 of the present embodiment. As shown in FIG. 12, the high-frequency transmitter / receiver 142 has an I-phase signal orthogonal to the received signal to which the cancel signal supplied from the cancel signal combiner 66 via the circuit switching unit 84 is added. And a received signal orthogonal transform unit (orthogonal demodulator) 144 for converting into a Q-phase signal, and an I-phase variable amplifying unit that is a variable gain amplifier that amplifies the received signal converted into an I-phase signal by the received signal orthogonal transform unit 144 92i, an I-phase reception signal A / D conversion unit 94i that digitally converts the I-phase signal output from the I-phase variable amplification unit 92i and stores it in the reception memory unit 42, and the reception signal orthogonal conversion unit 144. A Q-phase variable amplifier 92q, which is a variable gain amplifier that amplifies the received signal converted to the Q-phase signal, and digitally outputs the Q-phase signal output from the Q-phase variable amplifier 92q In other words, the Q-phase received signal A / D converter 94q stored in the reception memory unit 42 and the cancel signal distributed by the cancel signal distributor 80 are converted into an orthogonal I-phase signal and Q-phase signal. A signal quadrature transform unit 146, an I phase cancel signal amplifying unit 100i that amplifies the cancel signal converted into an I phase signal by the cancel signal quadrature transform unit 146, and an I phase output from the I phase cancel signal amplifying unit 100i An I-phase cancellation signal A / D conversion unit 102i that digitally converts the signal and stores it in the cancellation memory unit 40, and a Q-phase cancellation signal that amplifies the cancellation signal converted into a Q-phase signal by the cancellation signal orthogonal transformation unit 146 The amplification unit 100q and the Q-phase signal output from the Q-phase cancellation signal amplification unit 100q are And Q-phase canceling signal A / D converting unit 102q to be stored in the cancel memory unit 40 and barrel conversion includes. Here, the amplification factor control unit 54 provided in the central control unit 26 makes the amplification factor in the I-phase variable amplification unit 92i as much as possible within the limit allowed by the I-phase reception signal A / D conversion unit 94i. And the gain in the Q-phase variable amplifying unit 92q is controlled as much as possible within the limit allowed for the Q-phase received signal A / D converter 94q.

  The central control unit 26 of the RFID tag communication apparatus 140 according to the present embodiment executes RFID tag search control according to the flowchart of FIG. 9 described above. FIG. 13 is a flowchart for explaining a main part of adaptive cancel control by the central control unit 26 of the RFID tag communication apparatus 140 via the adaptive weight control unit 38, and corresponds to the control of FIG. 10 described above. is there. In the control shown in FIG. 13, first, in SA1 ′, the I-phase component and Q-phase component of the cancel signal (cancel input data) stored in the cancel memory unit 40 and the received signal ( I-phase component and Q-phase component of (input data) are read out. Next, after the above-described control of SA2 is executed, the cancel signal read from the cancel memory unit 40 and received in SA3 ′ corresponding to the operations of the cancel complex signal generation unit 106 and the complex signal generation unit 110. For each received signal read from the memory unit 42, complex signals XC and XI are generated with the I-phase component as the real part and the Q-phase component as the imaginary part. Then, after the above-described processing after SA4 is executed and adaptive cancel control is performed, the radio tag search control shown in FIG. 9 is restored.

  As described above, according to this embodiment, the reception signal orthogonal transform unit 144 that converts the reception signal into an I-phase signal and a Q-phase signal orthogonal to each other is provided, and the reception memory unit 42 performs the reception signal orthogonal transform. Since the I-phase signal and the Q-phase signal converted by the unit 144 are stored, the cancel signal can be suitably controlled based on the I-phase signal and the Q-phase signal as a result of the quadrature demodulation.

  Further, the I-phase variable amplification unit 92i and the Q-phase variable amplification unit 92q for amplifying the I-phase signal and the Q-phase signal converted by the reception signal orthogonal transform unit 144, and the I-phase variable amplification unit 92i and the Q-phase variable The I-phase signal output from the amplifier 92q, the I-phase received signal A / D converter 94i and the Q-phase received signal A / D converter 94q for digitally converting the Q-phase signal, and the I-phase variable amplifiers 92i and Q An amplification factor control unit 52 that controls the amplification factor in the phase variable amplification unit 92q as much as possible within the limits allowed by the I-phase reception signal A / D conversion unit 94i and the Q-phase reception signal A / D conversion unit 94q. Therefore, the I-phase signal and the Q-phase signal can be amplified as much as possible.

FIG. 14 is another example of a timing chart for explaining the adaptive control of the cancel weight by the adaptive cancel control unit 38 of the RFID tag communication apparatuses 12 and 140. The transmission control unit 50 responds to the convergence of the cancel signal. An aspect of controlling the command transmission end timing will be described. In the control shown in FIG. 14, the transmission of the transmission signal including the command is terminated when the cancellation weight WC has sufficiently converged by the adaptive control by the adaptive cancellation control unit 38. Specifically, when transmission of the command phase, that is, transmission of a transmission signal including a command for performing communication of information with the wireless tag 14 is completed after a predetermined time elapses from the start of the command phase. That is, when the cancel weight WC has not converged at the timing [3] of the adaptive cancel process shown in FIG. 14, a command extension phase is inserted after the command phase, and the transmission signal including the command until the cancel weight WC converges. Transmission is continued. When the cancel weight WC converges, transmission of a carrier wave that does not include a command is started, and reception of the response wave F _r from the wireless tag 14 is started.

  Thus, according to the present embodiment, the transmission control unit 50 controls the transmission signal transmission end timing in accordance with the convergence of the cancellation signal by the adaptive control of the adaptive cancellation control unit 38. In view of convergence of the cancel signal, substantial communication with the wireless tag 14 can be performed.

  In addition, the transmission control unit 50 is configured to stop transmission of a transmission signal including a command after the cancel signal has converged by the adaptive control of the adaptive cancellation control unit 38 and transmit a carrier wave not including the command. The cancel signal can be controlled prior to the substantial reception signal processing, and the communication with the wireless tag 14 can be reliably performed.

  The preferred embodiments of the present invention have been described in detail with reference to the drawings. However, the present invention is not limited to these embodiments, and may be implemented in other modes.

  For example, in the above-described embodiment, the digital signal processing unit 16, the high frequency transmission / reception unit 18, the central control unit 26, and the like are all provided as individual control devices. However, the present invention is not limited to this. Rather, for example, a DSP as a single control device, which is a so-called microcomputer system that includes a CPU, a ROM, a RAM, and the like and performs signal processing in accordance with a program stored in the ROM in advance using the temporary storage function of the RAM. As a control function of (Digital Signal Processor), various functions in the digital signal processing unit 16, the high frequency transmission / reception unit 18, the central control unit 26, and the like may be provided. In addition, the command bit string generation unit 30, the adaptive cancel control unit 38, the AM demodulation unit 44, and the like may be provided as individual control devices. The control by these control units may be digital signal processing or analog signal processing.

  In the above-described embodiment, the wireless tag communication devices 12 and 140 transmit and receive the transmission signal, and receive a reply signal returned from the wireless tag 14 according to the transmission signal. However, a transmission antenna and a reception antenna may be provided separately.

  In the above-described embodiment, the adaptive cancel control unit 38 controls the cancel signal during transmission of a transmission signal including a command for communicating information with the wireless tag 14, that is, in a command phase. However, the transmission of the transmission signal including the command may be started only after the control of the cancel signal is completed. In this way, the overall communication time is slightly longer than in the mode in which cancel control is performed during transmission of a transmission signal including a command, but the weight of the cancel signal can be converged by the simplest control possible. There are advantages.

  In addition, although not illustrated one by one, the present invention is implemented with various modifications within a range not departing from the gist thereof.

It is a figure explaining the radio | wireless tag communication system with which the radio | wireless tag communication apparatus of this invention is used suitably. It is a figure explaining the structure of the RFID tag communication apparatus which is one Example of this invention. FIG. 3 is a block diagram illustrating in detail a configuration of a high-frequency transmission / reception unit provided in the RFID tag communication apparatus of FIG. 2. It is a figure which illustrates the structure of the circular buffer used suitably as the cancellation memory part or reception memory part with which the RFID tag communication apparatus of FIG. 2 was equipped. FIG. 3 is a block diagram illustrating in detail a configuration of an adaptive cancel control unit provided in the RFID tag communication apparatus of FIG. 2. It is a figure explaining the structure of the cancellation weight initial value buffer with which the adaptive cancellation control part of FIG. 5 was equipped. FIG. 2 is a diagram illustrating a configuration of an RFID circuit element provided in an RFID tag that is a communication target of the RFID tag communication system of FIG. 1. 3 is a timing chart for explaining adaptive control of a cancellation weight by an adaptive cancellation control unit of the RFID tag communication apparatus of FIG. 3 is a flowchart for explaining a main part of RFID tag search control via a digital signal processing unit and a high-frequency transmission / reception unit by a central control unit of the RFID tag communication apparatus of FIG. 10 is a flowchart for explaining a main part of adaptive cancel control which is a part of the RFID tag search control shown in FIG. 9. It is a figure explaining the structure of the RFID tag communication apparatus which is the other Example of this invention. FIG. 3 is a block diagram illustrating in detail a configuration of a high-frequency transmission / reception unit provided in the RFID tag communication apparatus of FIG. 2. 10 is a flowchart illustrating a main part of another example of adaptive cancel control that is part of the RFID tag search control shown in FIG. 9. FIG. 12 is another example of a timing chart illustrating adaptive control of a cancel weight by the adaptive cancel control unit of the RFID tag communication apparatus illustrated in FIGS.

Explanation of symbols

12, 140: RFID tag communication device 14: RFID tag 20: antenna 38: adaptive cancel control unit (cancellation signal control unit)
40: cancellation memory unit 42: reception memory unit 54: amplification factor control unit 56: circuit switching control unit 60: carrier wave distribution unit 72: cancellation phase control unit 78: cancellation amplitude control unit 82: reception signal amplification unit 84: circuit switching unit 86: Local signal output unit 88: Reception signal frequency conversion unit 92: Variable amplification unit 92i: I phase variable amplification unit 92q: Q phase variable amplification unit 94: Reception signal A / D conversion unit 94i: I phase reception signal A / D Transformer 94q: Q-phase received signal A / D converter 144: Received signal orthogonal transform unit 146: Cancel signal orthogonal transform unit

Claims (21)

Communication of information with the wireless tag by receiving a reply signal sent back from the wireless tag according to the transmission signal by the antenna, and a transmission unit that transmits a predetermined transmission signal from the antenna toward the wireless tag A wireless tag communication device having a receiving unit for performing
A reception memory unit for storing a reception signal received by the antenna;
A carrier wave distribution unit for distributing the carrier wave of the transmission signal;
A cancel signal output unit that controls the amplitude and / or phase of the carrier wave distributed by the carrier wave distribution unit and outputs the canceled signal as a cancel signal;
The reception signal stored in the reception memory unit is read, and a control signal for controlling the amplitude and / or phase of the cancellation signal output from the cancellation signal output unit is output based on the read reception signal. A wireless tag communication device comprising: a cancel signal control unit. A cancel memory unit for storing a cancel signal output from the cancel signal output unit;
The cancel signal control unit reads the cancel signal stored in the cancel memory unit, and controls the amplitude and / or phase of the cancel signal output from the cancel signal output unit based on the read cancel signal. The wireless tag communication device according to claim 1, wherein The reception memory unit stores a reception signal that has been sampled and converted into digital reception data,
The cancellation memory unit stores a cancellation signal that has been sampled and converted into digital cancellation data.
The cancel signal control unit reads the digital reception data stored in the reception memory unit and the digital cancellation data stored in the cancellation memory unit, respectively, performs a predetermined calculation based on the digital reception data and the digital cancellation data, 3. The RFID tag communication apparatus according to claim 2, wherein an amplitude and / or phase of a cancel signal output from the cancel signal output unit is controlled based on a calculation result.   The cancellation signal control unit reads the reception signal stored in the reception memory unit, and adds the cancellation signal output from the cancellation signal output unit to the read reception signal. 4. The RFID tag communication device according to claim 1, wherein the RFID tag communication device controls amplitude and / or phase.   The cancellation signal control unit reads the reception signal stored in the reception memory unit, and adds the cancellation signal output from the cancellation signal output unit to the read reception signal, and is included in the reception signal. The RFID tag communication apparatus according to claim 4, wherein an amplitude and / or a phase of the cancel signal is controlled so that a carrier wave component is a predetermined value or less.   The cancellation signal control unit reads the digital reception data stored in the reception memory unit and the digital cancellation data stored in the cancellation memory unit, respectively, and the sum of the digital reception data and the digital cancellation data becomes a predetermined value or less. 6. The radio according to claim 1, wherein a weight for the amplitude and / or phase of the cancel signal is determined by adaptive calculation processing, and the amplitude and / or phase of the cancel signal is controlled based on the weight. Tag communication device. A local signal output unit for outputting a local signal having a predetermined frequency;
A frequency conversion unit that multiplies the received signal by the local signal output by the local signal output unit to obtain an intermediate frequency signal;
7. The RFID tag communication apparatus according to claim 1, wherein the reception memory unit stores the intermediate frequency signal converted by the frequency conversion unit. A variable amplifier for amplifying the intermediate frequency signal converted by the frequency converter;
An A / D converter that digitally converts the intermediate frequency signal output from the variable amplifier;
The wireless tag communication device according to claim 7, further comprising: an amplification factor control unit that controls an amplification factor in the variable amplification unit as much as possible within a limit allowed by the A / D conversion unit. An orthogonal transform unit that transforms the received signal into an I-phase signal and a Q-phase signal that are orthogonal to each other;
7. The RFID tag communication apparatus according to claim 1, wherein the reception memory unit stores the I-phase signal and the Q-phase signal converted by the orthogonal transform unit. A variable amplifying unit for amplifying the I-phase signal and the Q-phase signal converted by the orthogonal transform unit;
An A / D converter that digitally converts the I-phase signal and the Q-phase signal output from the variable amplifier;
The wireless tag communication device according to claim 9, further comprising: an amplification factor control unit that controls an amplification factor in the variable amplification unit as much as possible within a limit allowed by the A / D conversion unit. The transmitter is capable of selectively transmitting a transmission signal including a command for performing information communication with the wireless tag and a carrier wave not including the command,
The RFID tag communication apparatus according to any one of claims 1 to 10, wherein the cancel signal control unit controls an amplitude and / or a phase of the cancel signal during transmission of a transmission signal including the command.   12. The cancel signal control unit adaptively controls the amplitude and / or phase of the cancel signal based on a reception signal corresponding to a portion where a signal level in the transmission signal is a predetermined value or more. Any RFID tag communication device.   The RFID tag communication apparatus according to any one of claims 6 to 12, wherein the transmission unit controls transmission end timing of the transmission signal in accordance with convergence of the cancellation signal by adaptive control of the cancellation signal control unit.   14. The RFID tag communication according to claim 13, wherein the transmission unit stops transmission of a transmission signal including a command after the cancellation signal converges by adaptive control of the cancellation signal control unit, and transmits a carrier wave not including the command. apparatus. An amplifying unit for amplifying the reception signal to which the cancellation signal is added;
A circuit switching unit for switching between a circuit through which the received signal passes through the amplification unit and a circuit through which the reception signal does not pass through;
The wireless tag communication device according to claim 1, further comprising: a circuit switching control unit that controls switching of the circuit by the circuit switching unit in accordance with the reception signal to which the cancel signal is added.   16. The RFID tag communication apparatus according to claim 1, wherein a capacity of the reception memory unit is smaller than a size corresponding to a command included in the transmission signal.   The RFID tag communication apparatus according to any one of claims 1 to 16, wherein a capacity of the cancel memory unit is smaller than a size corresponding to a command included in the transmission signal.   The reception memory unit is a two-stage buffer device having two storage areas. First, the reception signal is stored in one of the storage areas, and the reception is received in the other storage area when the storage area is saturated. The RFID tag communication device according to any one of claims 1 to 17, which stores a signal.   The cancellation signal control unit reads a reception signal stored in the storage area when one of the storage areas in the reception memory unit is saturated, and outputs the reception signal from the cancellation signal output unit based on the read reception signal 19. The RFID tag communication apparatus according to claim 18, which controls the amplitude and / or phase of the cancel signal.   The cancel memory unit is a two-stage buffer device having two storage areas. First, a cancel signal output by a series of controls by the cancel signal control unit is stored in one of the storage areas, and the next series The wireless tag communication device according to claim 1, wherein a cancel signal output by the control of is stored in the other storage area.   The cancel signal control unit reads a cancel signal stored in one storage area in the cancel memory unit, and based on the read cancel signal, the cancel signal amplitude and / or 21. The RFID tag communication apparatus according to claim 20, wherein phase control is performed, and the controlled cancel signal is repeatedly stored in the cancel memory unit.

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