JP4631794B2 - Wireless communication device - Google Patents

Description

  The present invention relates to an improvement of a wireless communication apparatus having a cancel circuit for suppressing a sneak signal from a transmission side.

  2. Description of the Related Art A wireless communication device is known that includes a transmission unit that transmits a predetermined transmission signal from a transmission antenna and a reception unit that receives a reply signal returned in response to the transmission signal by a reception antenna. For example, an RFID (Radio Frequency Identification) system RFID tag communication device (interrogator) that reads information without contact from a small RFID 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, in order to sufficiently remove the sneak signal included in the received signal by the technique as described above, it is necessary to accurately detect the strength of the sneak signal from the direct wave, that is, from the transmission side. The signal strength could not be accurately detected, and the sneak signal included in the received signal could not be sufficiently removed. That is, there has been a demand for the development of a wireless communication apparatus that can sufficiently remove the sneak signal from the transmission side included in the received signal.

  The present invention has been made against the background of the above circumstances, and an object of the present invention is to provide a wireless communication apparatus capable of sufficiently removing a sneak signal from a transmission side included in a reception signal. .

In order to achieve such an object, the gist of the present invention is that a transmission signal is transmitted from a transmission antenna, and a return signal returned from a communication target according to the transmission signal is received by a reception antenna. A wireless communication device that communicates information with the communication target, a direct wave detection unit that detects a direct wave component from a transmission side in a reception signal received by the reception antenna, and the direct wave A signal processing unit that processes the direct wave component detected by the detection unit, and a digital signal that is received signal received by the receiving antenna or the direct wave component that is detected by the direct wave detection unit, to the signal processing unit generation and supplies the a / D converter, a cancel signal for suppressing the direct wave component from the transmitting side in the received signal based on the processing results of the signal processing unit A cancel signal generator for, and a cancel signal combining unit for combining the received signals received cancellation signal generated and by the receiving antenna by the cancellation signal generation section, possess, the direct wave detector A direct wave extracting unit for extracting a direct wave component in the received signal in accordance with a difference between the received signal received by the receiving antenna and a predetermined reference signal, the direct wave extracting unit and the A / D converting unit And a reference adjustment unit that determines a reference value of the A / D conversion unit, and a switch that connects or disconnects a circuit between the direct wave extraction unit and the reference adjustment unit. It is characterized by this.

If it does in this way, the direct wave detection part which detects the direct wave component from the transmission side in the received signal received by the receiving antenna, and the signal processing which processes the direct wave component detected by the direct wave detection part An A / D converter that digitally converts the received signal received by the receiving antenna or the direct wave component detected by the direct wave detector and supplies the signal to the signal processor , and the signal processor A cancel signal generator for generating a cancel signal for suppressing a direct wave component from the transmission side in the received signal based on a processing result, a cancel signal generated by the cancel signal generator and the receiving antenna and a cancel signal combining unit for combining the reception signal received, possess, the direct wave detecting unit, by the receiving antenna A direct wave extraction unit that extracts a direct wave component in the received signal according to a difference between the received signal and a predetermined reference signal, and is provided between the direct wave extraction unit and the A / D conversion unit. as a reference adjustment unit for determining a reference value of the a / D conversion unit, said direct wave extraction unit and switch for connecting or disconnecting the circuit between the reference adjustment unit since, is intended to include, the received signal Te can be detected in a practical manner the direct wave component included in the direct wave namely because it is possible to accurately detect the echo signal from the transmitting side, the cancellation signal based on the detection result suitably Can be controlled. That is, it is possible to provide a wireless communication apparatus that can sufficiently remove the sneak signal from the transmission side included in the received signal.

  Here, preferably, the cancellation signal generation unit includes a cancellation phase control unit that controls a phase of the cancellation signal and / or a cancellation amplitude control unit that controls an amplitude. In this way, the cancel signal can be controlled in a practical manner.

  Preferably, a first circuit that supplies a reception signal received by the reception antenna to the signal processing unit and a direct wave component detected by the direct wave detection unit are supplied to the signal processing unit. A circuit switching unit that switches between the second circuit and the second circuit is provided. In this way, the circuit configuration can be simplified.

  Preferably, the signal processing unit has a phase and / or phase of the cancellation signal based on a reference value and an actual output value in digital conversion of the direct wave component by the A / D conversion unit from a predetermined relationship. Alternatively, the calculation value for determining the amplitude is calculated, and the cancellation signal generation unit controls the phase and / or amplitude of the cancellation signal based on the calculation value from a predetermined relationship. In this way, the cancel signal can be suitably controlled based on the direct wave component.

  Preferably, the signal processing unit includes a storage unit that stores a signal supplied from the A / D conversion unit, and the A / D conversion unit performs digital conversion of the direct wave component. The reference value is stored in the storage unit before being displayed. In this way, the direct wave component can be suitably processed based on the reference value stored in the storage unit.

  Preferably, the apparatus further includes an orthogonal demodulation unit that demodulates the reception signal received by the reception antenna as an I-phase component and a Q-phase component that are orthogonal to each other. In this way, with respect to the quadrature detection circuit that is particularly affected by the sneak signal from the transmission side, the sneak signal from the transmission side can be suitably suppressed in a wide phase range.

  Preferably, the direct wave detection unit, the A / D conversion unit, and the circuit switching unit are individually provided corresponding to the I-phase component and the Q-phase component demodulated by the quadrature demodulation unit. In this way, the direct wave component corresponding to each of the I-phase component and the Q-phase component can be quickly detected.

  Preferably, the direct wave extraction unit, the A / D conversion unit, and the circuit switching unit are individually provided corresponding to the I-phase component and the Q-phase component demodulated by the quadrature demodulation unit, and the I A reference adjustment unit that is provided between the direct wave extraction unit and the A / D conversion unit corresponding to each of the phase component and the Q phase component, and determines the reference value of the A / D conversion unit, and the I phase component or the Q phase A switch for connecting or disconnecting a circuit between the direct wave extraction unit corresponding to the component and the reference adjustment unit, and an output from the direct wave extraction unit provided corresponding to the I-phase component to the switch A second circuit switching unit that switches between a first circuit to be supplied and a second circuit to supply an output from the direct wave extraction unit provided corresponding to the Q-phase component to the switch; is there. In this way, the direct wave component corresponding to each of the I-phase component and the Q-phase component can be detected with a simple circuit.

  Preferably, the signal processing unit performs the A / D conversion based on a predetermined relationship with respect to each of the I-phase component and the Q-phase component supplied via the direct wave detection unit and the A / D conversion unit. A calculation value for determining the phase and / or amplitude of the cancel signal is calculated based on a reference value and an actual output value in the digital conversion by the unit. In this way, an operation value for controlling the cancel signal can be calculated based on the direct wave component.

  Preferably, the signal processing unit is configured to use a reference in digital conversion by the A / D conversion unit for each of the I-phase component and the Q-phase component supplied via the direct wave detection unit and the A / D conversion unit. The difference between the value and the actual output value is obtained, and the square root of the sum of the squares of the differences corresponding to the I-phase component and Q-phase component is calculated as the calculated value. In this way, it is possible to calculate a calculation value for controlling the cancel signal in a practical manner based on the direct wave component.

  Preferably, the cancellation signal generation unit controls the phase and / or amplitude of the cancellation signal so that the calculated value calculated by the signal processing unit is as small as possible. In this way, the cancellation signal can be controlled in a practical manner based on the calculated value.

  Preferably, the cancel signal generation unit includes a difference between a reference value and an actual output value in digital conversion performed by the A / D conversion unit calculated in correspondence with the I-phase component by the signal processing unit. , The phase of the cancel signal and / or the difference between the reference value and the actual output value in the digital conversion by the A / D converter calculated corresponding to the Q-phase component, whichever is greater Alternatively, the amplitude is controlled. In this way, the cancellation signal can be controlled in a practical manner based on the calculated value.

  Preferably, the signal processing unit processes the direct wave component with respect to a reception signal received by the reception antenna in accordance with a carrier wave transmitted from the transmission antenna or a signal including a predetermined command. Is. In this way, it is possible to perform processing such as detection of the direct wave component or control of the cancellation signal in any of the carrier wave not including the command and the signal including the command.

  Preferably, the communication target is a wireless tag capable of writing and / or reading information via wireless communication, and the wireless communication device transmits a predetermined transmission signal toward the wireless tag. A wireless tag communication apparatus that transmits information by an antenna and communicates information with the wireless tag by receiving a reply signal returned from the wireless tag in response to the transmission signal by the receiving antenna. . In this way, it is possible to suitably suppress the sneak signal from the transmission side regarding the RFID tag communication apparatus that is particularly affected by the sneak signal from the transmission side.

  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 communication apparatus of the present invention is preferably used. The wireless tag communication system 10 includes a wireless tag communication device 12 that is an embodiment of the wireless communication device of the present invention and a single or multiple (single in FIG. 1) wireless communication target of the wireless tag communication device 12. The RFID tag is a so-called RFID (Radio Frequency Identification) system. 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 apparatus 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. ) Modulates the interrogation wave F _c and sends it back as a response wave F _r (reply signal) to the RFID tag communication apparatus 12, thereby providing information 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 RFID tag communication apparatus 12 according to the present embodiment transmits a transmission signal from the antenna 16 for transmission / reception to the RFID tag 14 according to the transmission signal. A transmission / reception unit 18 that performs transmission / reception processing for receiving a reply signal returned from the wireless tag 14 through the antenna 16, a local oscillator 20 that generates a predetermined local signal, and a local signal supplied from the local oscillator 20 The cancel signal generator 22 for generating a cancel signal for suppressing the direct wave component from the transmission side in the received signal received by the antenna 16, the cancel signal generated by the cancel signal generator 22, and the above Cancel signal synthesizing unit 24 that synthesizes the received signal received by antenna 16 and its cancellation A quadrature demodulator 26 that demodulates the received signal supplied via the signal synthesizer 24 as an I-phase component (in-phase component) and a Q-phase component (orthogonal component) based on the local signal supplied from the local oscillator 20. An I-phase direct wave detection unit 28 for detecting a direct wave component from the transmission side in the I-phase component supplied from the quadrature demodulation unit 26, and a predetermined one of the I-phase components supplied from the quadrature demodulation unit 26 The signal processing unit 44 converts the signal output from the I-phase bandpass filter 30 that passes the signal in the frequency band and the signal output from the I-phase direct wave detection unit 28 or the signal output from the I-phase bandpass filter 30 into a digital signal. An I-phase A / D converter 32 to be supplied to the first circuit, a first circuit for supplying a signal output from the I-phase bandpass filter 30 to the I-phase A / D converter 32, and the I-phase direct wave detection Part The I-phase circuit switching unit 34 (SW2i) that switches between the second circuit that supplies the signal output from the I-phase A / D conversion unit 32 and the Q-phase component supplied from the quadrature demodulation unit 26 A Q-phase direct wave detection unit 36 for detecting a direct wave component from the transmission side, and a Q-phase bandpass filter 38 for passing a signal in a predetermined frequency band among the Q-phase components supplied from the quadrature demodulation unit 26; A Q-phase A / D conversion unit 40 that digitally converts the signal output from the Q-phase direct wave detection unit 36 or the signal output from the Q-phase bandpass filter 38 and supplies the signal to the signal processing unit 44; A first circuit that supplies a signal output from the Q-phase bandpass filter 38 to the Q-phase A / D converter 40, and a signal output from the Q-phase direct wave detector 36 is the Q-phase A / D. Supply to the conversion unit 40 Q-phase circuit switching unit 42 (SW2q) for switching between the second circuit and the signal processing unit 44 that processes a signal supplied from the I-phase A / D conversion unit 32 or the Q-phase A / D conversion unit 40. And a control unit 46 for controlling the transmission / reception operation by the transmission / reception unit 18 and the cancel signal control operation by the cancellation signal generation unit 22 based on the processing result by the signal processing unit 44.

  The cancel signal generator 22 includes a variable phase shifter 48 that is a cancel phase controller that controls the phase of the cancel signal, and a variable attenuator 50 that is a cancel amplitude controller that controls the amplitude. Cancellation for suppressing the direct wave component from the transmission side in the received signal by controlling the phase and / or amplitude of the local signal supplied from the local oscillator 20 by the variable phase shifter 48 and variable attenuator 50 Generate a signal. The cancel signal is controlled based on the processing result of the signal processing unit 44 as will be described later. The cancel signal generated by the cancel signal generator 22 is combined (added) to the received signal in the cancel signal combiner 24, so that a direct wave component (around signal) from the transmission side included in the received signal is obtained. ) Is suppressed.

  In the communication with the wireless tag 14 by the wireless tag communication device 12, both the circuit switching units 34 and 42 are connected to the a side. As a result, the first circuit is established, and the reception signal received by the antenna 16 is supplied to the signal processing unit 44 via the band-pass filters 30, 36 and the like. Further, when controlling the cancel signal generated by the cancel signal generating unit 22, both the circuit switching units 34 and 42 are connected to the b side. As a result, the second circuit is established, and the direct wave component detected by the direct wave detection units 28 and 36 is supplied to the signal processing unit 44.

  The I-phase direct wave detection unit 28 extracts a direct wave component in the I-phase component according to a difference between the I-phase component (I-phase signal) supplied from the quadrature demodulation unit 26 and a predetermined reference signal. I-phase direct wave extraction unit 52 as a dynamic amplifier, and a reference value for the I-phase A / D conversion unit 32 provided between the I-phase direct wave extraction unit 52 and the I-phase A / D conversion unit 32 And an I-phase switch 56 (SW1i) that connects or disconnects the circuit between the I-phase direct wave extraction unit 52 and the I-phase reference adjustment unit 54. As shown in FIG. 2, the b-side terminal of the I-phase switch 56 is grounded, and the I-phase switch 56 is connected to the b-side and the I-phase circuit switching unit 34 is connected to the b-side. Then, the input voltage of the I-phase A / D conversion unit 32 is set to a predetermined reference value by the I-phase reference adjustment unit 54. This reference value is preferably an intermediate value of a voltage range that can be input to the I-phase A / D converter 32, and is 1.65 V, for example. When the I-phase switch 56 is connected to the a side and the I-phase circuit switching unit 34 is connected to the b side, the output from the I-phase direct wave extraction unit 52 is the I-phase reference adjustment unit. 54 and the I-phase A / D conversion unit 32 via the I-phase circuit switching unit 34.

  The Q-phase direct wave detection unit 36 extracts a direct wave component in the Q-phase component according to the difference between the Q-phase component (Q-phase signal) supplied from the quadrature demodulation unit 26 and a predetermined reference signal. A Q-phase direct wave extraction unit 58 as a dynamic amplifier, and a reference value of the Q-phase A / D conversion unit 40 provided between the Q-phase direct wave extraction unit 58 and the Q-phase A / D conversion unit 40 A Q-phase reference adjusting unit 60 for determining the Q-phase, and a Q-phase switch 62 (SW1q) for connecting or disconnecting the circuit between the Q-phase direct wave extracting unit 58 and the Q-phase reference adjusting unit 60. As shown in FIG. 2, the b-side terminal of the Q-phase switch 62 is grounded, and the Q-phase switch 62 is connected to the b-side and the Q-phase circuit switching unit 42 is connected to the b-side. Then, the input voltage of the Q-phase A / D conversion unit 40 is set to a predetermined reference value by the Q-phase reference adjustment unit 60. This reference value is preferably an intermediate value of a voltage range that can be input to the Q-phase A / D converter 40, and is, for example, 1.65V. When the Q phase switch 62 is connected to the a side and the Q phase circuit switching unit 42 is connected to the b side, the output from the Q phase direct wave extracting unit 58 is the Q phase reference adjusting unit. 60 and the Q-phase A / D converter 40 via the Q-phase circuit switching unit 42.

  The signal processing unit 44 includes a CPU, a ROM, a RAM, and the like, and is a so-called microcomputer system that performs signal processing according to a program stored in advance in the ROM while using a temporary storage function of the RAM. A storage unit 64 that stores a signal supplied from the D conversion unit 32 or the Q-phase A / D conversion unit 40 is included. The signal processing unit 44 is based on a reference value and an actual output value in digital conversion of the direct wave component by the I-phase A / D conversion unit 32 and the Q-phase A / D conversion unit 40 from a predetermined relationship. An operation value for determining the phase and / or amplitude of the cancel signal is calculated. Preferably, the I-phase A / D conversion unit 32 and the Q-phase A / D conversion unit 40 are respectively supplied from the I-phase A / D conversion unit 40 and the I-phase A / D conversion unit according to a predetermined relationship. 32. An operation value for determining the phase and / or amplitude of the cancel signal is calculated based on the reference value and the actual output value in the digital conversion by the Q-phase A / D converter 40. The calculated value calculated by the signal processing unit 44 is supplied to the control unit 46. This calculation value calculation will be described later with reference to the flowchart of FIG.

  The control unit 46 includes a CPU, a ROM, a RAM, and the like, and is a so-called microcomputer system that performs signal processing according to a program stored in advance in the ROM while using a temporary storage function of the RAM. It functions as a cancel signal controller that controls the phase and / or amplitude of the cancel signal generated by the cancel signal generator 22 based on the processing result. Further, the transmission timing of the transmission signal by the transmission / reception unit 18 is controlled, or a carrier wave not including a command is transmitted by the transmission / reception unit 18 for direct wave component detection. Perform transmission / reception control.

FIG. 3 is a diagram for explaining the configuration of the RFID circuit element 66 provided in the RFID tag 14. As shown in FIG. 3, the RFID circuit element 66 has an antenna 68 for communicating with the RFID tag communication device 12 and is connected to the antenna 68 from the RFID tag communication device 12. And an IC circuit unit 70 for processing the transmission signal. The IC circuit unit 70 rectifies the interrogation wave F _c received from the RFID tag communication device 12 received by the antenna 68, and stores the energy of the interrogation wave F _c rectified by the rectification unit 72. Power supply unit 74, a clock extraction unit 76 that extracts a clock signal from the carrier wave received by the antenna 68 and supplies the clock signal to the control unit 82, and a memory unit that functions as a storage unit that can store a predetermined information signal 78, the modulation / demodulation unit 80 connected to the antenna 68 for modulating and demodulating the signal, and the operation of the RFID circuit element 66 through the rectification unit 72, the clock extraction unit 76, the modulation / demodulation unit 80, etc. The control part 82 for performing is functionally included. The control unit 82 performs control to store the predetermined information in the memory unit 78 by communicating with the RFID tag communication device 12, and transmits the interrogation wave F _c received by the antenna 68 in the modulation / demodulation unit 80. After performing modulation based on the information signal stored in the memory unit 78, basic control such as control of reflecting back from the antenna 68 as the response wave _Fr is executed.

  FIG. 4 is a flowchart for explaining a main part of direct wave cancellation control by the signal processing unit 44 and the control unit 46 of the RFID tag communication apparatus 12, and is repeatedly executed at a predetermined cycle.

First, in step (hereinafter step is omitted) S1, the I-phase circuit switching unit 34 (SW1i) is on the b side, and the I-phase switch 56 (SW2i) of the I-phase direct wave detection unit 28 is on the b side. The output _{mi0 of the} I-phase A / D conversion unit 32 at that time is stored in the storage unit 64. The output _mi0 is a value corresponding to the reference value of the I-phase reference adjusting unit 54. The Q-phase circuit switching unit 42 (SW1q) is connected to the b side, and the Q-phase switch 62 (SW2q) of the Q-phase direct wave detection unit 36 is connected to the b-side. The output m _q0 of the conversion unit 40 is stored in the storage unit 64. This output m _q0 is a value corresponding to the reference value of the Q-phase reference adjustment unit 60.

Next, in S2, the I-phase switch 56 of the I-phase direct wave detection unit 28 is switched to the a side, and the Q-phase switch 62 of the Q-phase direct wave detection unit 36 is switched to the a side. 18, a predetermined transmission signal is transmitted from the antenna 16. This transmission signal may be a signal including a predetermined command or a carrier wave not including a command. Then, the output m _{i1 of the} I-phase A / D conversion unit 32 and the output m _{q1 of the} Q-phase A / D conversion unit 40 corresponding to the transmission signal are stored in the storage unit 64. The outputs m _i1 and m _q1 correspond to the direct wave component of the I phase component detected by the I phase direct wave detection unit 28 and the direct wave component of the Q phase component detected by the Q phase direct wave detection unit 36, respectively. The value to be

Next, in S3, with respect to the I-phase component supplied via the I-phase direct wave detector 28 and the I-phase A / D converter 32, the reference value in the digital conversion by the I-phase A / D converter 32 and The difference from the actual output value is calculated. That is, the difference m _i2 (= m _i1 −m _i0 ) between the output m _i1 corresponding to the direct wave component detected in S2 and the output m _i0 corresponding to the reference value detected in S1 is calculated. . In addition, with respect to the Q-phase component supplied via the Q-phase direct wave detection unit 36 and the Q-phase A / D conversion unit 40, a reference value and an actual output value in digital conversion by the Q-phase A / D conversion unit 40 The difference is calculated. That is, a difference m _q2 (= m _q1 −m _q0 ) between the output m _q1 corresponding to the direct wave component detected in S2 and the output m _q0 corresponding to the reference value detected in S1 is calculated. .

Next, in S4, the square root m ₃ (= {m _i2 ² + m _q2 ² } ^1/2) of the sum of the squares of the differences m _i2 and m _q2 corresponding to the I-phase component and the Q-phase component calculated in S3. ) Is calculated as a calculated value. This calculated value is supplied to the control unit 46 in order to determine the phase and / or amplitude of the cancel signal.

Next, in S5, the operation value supplied from the signal processing unit 44, that is, m ₃ calculated in S4 is reduced as much as possible through the variable phase shifter 48 and the variable attenuator 50. The phase and / or amplitude of the cancellation signal is controlled.

  Next, in S6, the I-phase circuit switching unit 34 is switched to the a side and the Q-phase circuit switching unit 42 is switched to the a side, respectively, and a transmission signal including a predetermined command is transmitted from the antenna 16 by the transmission / reception unit 18. It is transmitted toward the wireless tag 14. Then, a reply signal returned from the wireless tag 14 according to the transmission signal is received by the antenna 16, and after the cancel signal is synthesized by the cancel signal synthesis unit 24, it is demodulated by the orthogonal demodulation unit 26. Then, communication with the wireless tag 14 is performed, and this routine is terminated.

In the control described above, the control unit 46 controls the cancel signal based on the calculated value m ₃ calculated corresponding to the I-phase component and the Q-phase component. The difference m _i2 between the reference value and the actual output value in the digital conversion by the I-phase A / D conversion unit 32 calculated by the unit 44 corresponding to the I-phase component, and the Q-phase component The cancellation signal may be controlled based on the larger one of the difference m _q2 between the reference value and the actual output value in the digital conversion by the Q-phase A / D converter 40. .

  Thus, according to the present embodiment, the I-phase direct wave detection unit 28 and the Q-phase direct wave detection unit 36 that detect the direct wave component from the transmission side in the reception signal received by the antenna 16, and these I A signal processing unit 44 that processes the direct wave component detected by the phase direct wave detection unit 28 and the Q phase direct wave detection unit 36, and a direct signal from the transmission side in the received signal based on a processing result by the signal processing unit 44. Cancel signal generator 22 for generating a cancel signal for suppressing wave components, and a cancel signal combiner for combining the cancel signal generated by cancel signal generator 22 and the received signal received by antenna 16 24, it is possible to accurately detect a direct wave, that is, a sneak signal from the transmission side, and based on the detection result, The Yanseru signal can be suitably controlled. That is, it is possible to provide the wireless tag communication device 12 that can sufficiently remove the sneak signal from the transmission side included in the received signal.

  In addition, since it has a quadrature demodulator 26 that demodulates the received signal received by the antenna 16 as an I-phase component and a Q-phase component, regarding the quadrature detection circuit that is particularly affected by the sneak signal from the transmission side, The sneak signal from the transmission side can be suitably suppressed.

  In addition, the direct wave detection units 28 and 36, the A / D conversion units 32 and 40, and the circuit switching units 34 and 42 are individually associated with the I-phase component and the Q-phase component demodulated by the quadrature demodulation unit 26. Therefore, the direct wave component corresponding to each of the I-phase component and the Q-phase component can be quickly detected.

  The cancel signal generator 22 includes a variable phase shifter 48 that functions as a cancel phase controller that controls the phase of the cancel signal, and a variable attenuator 50 that functions as a cancel amplitude controller that controls amplitude. Therefore, the cancel signal can be controlled in a practical manner.

  The first circuit that supplies the reception signal received by the antenna 16 to the signal processing unit 44, and the direct wave component detected by the I-phase direct wave detection unit 28 and the Q-phase direct wave detection unit 36 Since the I-phase circuit switching unit 34 and the Q-phase circuit switching unit 42 that switch the second circuit supplied to the signal processing unit 44 are included, the configuration of the circuit can be simplified.

  Also, the received signal received by the antenna 16 or the direct wave component detected by the I-phase direct wave detection unit 28 and the Q-phase direct wave detection unit 36 is digitally converted and supplied to the signal processing unit 44. Since the A / D converter 32 and the Q-phase A / D converter 40 are included, various processes relating to the received signal or the direct wave component can be performed by digital signal processing.

  The I-phase direct wave detector 28 extracts the direct wave component in the I-phase component according to the difference between the I-phase component of the received signal received by the antenna 16 and a predetermined reference signal. A wave extraction unit 52, an I-phase reference adjustment unit that is provided between the I-phase direct wave extraction unit 52 and the I-phase A / D conversion unit 32 and determines a reference value of the I-phase A / D conversion unit 32 54, and an I-phase switch 56 for connecting or disconnecting a circuit between the I-phase direct wave extraction unit 52 and the I-phase reference adjustment unit 54, and is included in the I-phase component of the received signal. The direct wave component can be detected in a practical manner.

  The Q-phase direct wave detection unit 36 extracts a direct-wave component in the Q-phase component according to the difference between the Q-phase component of the received signal received by the antenna 16 and a predetermined reference signal. A wave extraction unit 58 and a Q phase reference adjustment unit which is provided between the Q phase direct wave extraction unit 58 and the Q phase A / D conversion unit 40 and determines a reference value of the Q phase A / D conversion unit 40 60 and a Q-phase switch 62 that connects or disconnects the circuit between the Q-phase direct wave extraction unit 58 and the Q-phase reference adjustment unit 60, and is included in the Q-phase component of the received signal. The direct wave component can be detected in a practical manner.

  In addition, the signal processing unit 44 uses the reference value and the actual output value in the digital conversion of the direct wave component by the I-phase A / D conversion unit 32 and the Q-phase A / D conversion unit 40 from a predetermined relationship. The control unit 46 calculates a calculation value for determining the phase and / or amplitude of the cancel signal based on the calculation value, and the control unit 46 generates the cancel signal generation unit 22 based on the calculation value based on a predetermined relationship. Since the phase and / or amplitude of the cancel signal to be controlled is controlled, the cancel signal can be suitably controlled based on the direct wave component.

The signal processing unit 44 includes a storage unit 64 that stores signals supplied from the I-phase A / D conversion unit 32 and the Q-phase A / D conversion unit 40. The I-phase A / D Since the conversion unit 32 and the Q-phase A / D conversion unit 40 perform digital conversion of the direct wave component, the outputs m _i0 and m _q0 corresponding to the reference value are stored in the storage unit 64. The direct wave component can be suitably processed based on the outputs m _i0 and m _q0 corresponding to the reference values stored in the storage unit 64.

In addition, the signal processing unit 44 determines the A-phase component and the Q-phase component supplied via the direct wave detection units 28 and 36 and the A / D conversion units 32 and 40 from the predetermined relationship. Calculation values for determining the phase and / or amplitude of the cancel signal based on the outputs m _i0 and m _q0 and the actual output values m _i1 and m _q1 corresponding to the reference values in the digital conversion by the / D converters 32 and 40 Therefore, an operation value for controlling the cancel signal can be calculated based on the direct wave component.

In addition, the signal processing unit 44 has an A / D conversion unit 32, an I-phase conversion unit 32, and an A / D conversion unit 32 and 40 that are supplied via the direct wave detection units 28 and 36 and the A / D conversion units 32 and 40, respectively. Differences m _i2 and m _q2 between the reference value and the actual output value in the digital conversion by 40 are obtained, and the square root m ₃ of the sum of the squares of the differences corresponding to the I-phase component and Q-phase component is calculated as the calculated value. Therefore, an operation value for controlling the cancel signal can be calculated in a practical manner based on the direct wave component.

Further, the control unit 46 sets the phase and / or amplitude of the cancel signal generated by the cancel signal generation unit 22 so that the calculated value m ₃ calculated by the signal processing unit 44 is as small as possible. It is something to control. In this way, the cancellation signal can be controlled in a practical manner based on the calculated value.

Further, the control unit 46 determines the difference m _i2 between the reference value and the actual output value in the digital conversion by the I-phase A / D conversion unit 32 calculated by the signal processing unit 44 corresponding to the I-phase component. And the difference m _q2 between the reference value and the actual output value in the digital conversion by the Q-phase A / D converter 40 calculated corresponding to the Q-phase component, based on whichever is greater Since the phase and / or amplitude of the cancel signal generated by the cancel signal generator 22 is controlled, the cancel signal can be controlled in a practical manner based on the calculated value.

  In addition, the signal processing unit 44 performs processing of the direct wave component on a received signal received by the antenna 16 in accordance with a carrier wave transmitted from the antenna 16 or a signal including a predetermined command. The detection of the direct wave component or the control of the cancel signal can be performed on any of the carrier wave not including the command and the signal including the command.

  The communication target is a wireless tag 14 capable of writing and / or reading information via wireless communication. The wireless communication device sends a predetermined transmission signal to the wireless tag 14 via the antenna 16. A wireless tag communication device 12 that transmits information and communicates with the wireless tag 14 by receiving a reply signal returned from the wireless tag 14 in response to the transmission signal by the antenna 16. Therefore, the sneak signal from the transmission side can be suitably suppressed for the RFID tag communication apparatus 12 that is particularly affected by the sneak signal from the transmission side.

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

  FIG. 5 is a diagram for explaining the configuration of a wireless tag communication device 84 which is a preferred embodiment of the wireless communication device of the present invention. As shown in FIG. 5, the RFID tag communication device 84 of the present embodiment is provided between the direct wave extraction units 52 and 58 and the A / D conversion units 32 and 40 corresponding to the I-phase component and the Q-phase component, respectively. A reference adjusting unit 86 for determining a reference value of the A / D conversion units 32 and 40, a direct wave extracting unit 52 and 58 corresponding to the I-phase component or the Q-phase component, and a reference adjusting unit 86 thereof. A switch 88 (SW1) for connecting or disconnecting a circuit between the first circuit and a first circuit for supplying an output from the I-phase direct wave extraction unit 52 provided corresponding to the I-phase component to the switch 88; A second circuit switching unit 90 (SW3) that switches between a second circuit that supplies an output from the Q-phase direct wave extraction unit 58 provided corresponding to the Q-phase component to the switch 88, It is prepared for. The terminal on the b side of the switch 88 is grounded. When the switch 88 is connected to the b side and the circuit switching units 34 and 42 are connected to the b side, the A / D conversion unit 32 is connected. , 40 is set to a predetermined reference value by the reference adjusting unit 86. This reference value is preferably an intermediate value of a voltage range that can be input to the A / D converters 32 and 40, for example, 1.65V. When the switch 88 is connected to the a side and the circuit switching units 34 and 42 are connected to the b side, the I-phase direct wave extraction unit 52 or the Q-phase direct wave extraction unit 58 The output is supplied to the A / D converters 32 and 40 via the reference adjusting unit 86 and the circuit switching units 34 and 42. When the circuit switching unit 90 is connected to the a side, the output from the I-phase direct wave extraction unit 52 is input to the switch 88, and when connected to the b side, the Q-phase direct wave extraction is performed. The output from the unit 58 is input to the switch 88. In the RFID tag communication device 84, the I-phase direct wave extraction unit 52, the reference adjustment unit 86, and the switch 88 provide an I-phase direct wave detection unit, the Q-phase direct wave extraction unit 58, the reference adjustment unit 86, And the Q phase direct wave detection part is comprised from the switch 88, respectively.

  FIG. 6 is a flowchart for explaining a main part of the direct wave cancellation control by the signal processing unit 44 and the control unit 46 of the RFID tag communication apparatus 84, and is repeatedly executed at a predetermined cycle. In the control shown in FIG. 6, the steps common to the control of FIG. 4 described above are denoted by the same reference numerals and description thereof is omitted.

First, in S7, the switch 88 (SW1) is connected to the b side and the circuit switching units 34 (SW2i) and 42 (SW2q) are connected to the b side, and the A / D conversion unit 32 at that time is connected. 40, the outputs m _i0 and m _q0 are stored in the storage unit 64, respectively. The outputs m _i0 and m _q0 are values corresponding to the reference value of the reference adjusting unit 86. At this time, the circuit switching unit 90 (SW3) may be connected to either the a side or the b side.

Next, in S <b> 8, the circuit switching unit 90 is switched to the a side, and a predetermined transmission signal is transmitted from the antenna 16 by the transmission / reception unit 18. This transmission signal may be a signal including a predetermined command or a carrier wave not including a command. Then, the output _{mi1 of the} I-phase A / D conversion unit 32 corresponding to the transmission signal is stored in the storage unit 64. The output _mi1 is a value corresponding to the direct wave component of the I-phase component extracted by the I-phase direct wave extraction unit 52.

Next, in S <b> 9, the circuit switching unit 90 is switched to the b side, and a predetermined transmission signal is transmitted from the antenna 16 by the transmission / reception unit 18. This transmission signal may be a signal including a predetermined command or a carrier wave not including a command. Then, the output m _{q1 of the} Q-phase A / D conversion unit 40 corresponding to the transmission signal is stored in the storage unit 64. The output m _q1 has a value corresponding to the direct wave component of the Q phase component extracted by the Q phase direct wave extraction unit 58. Then, after the processes of S3 to S6 described above are executed, this routine is terminated.

  As described above, according to this embodiment, the direct wave extraction units 52 and 58, the A / D conversion units 32 and 40, and the I / D conversion units 32 and 40 corresponding to the I-phase component and the Q-phase component demodulated by the quadrature demodulation unit 26, The circuit switching units 34 and 40 are individually provided, and are provided between the direct wave extraction units 52 and 58 and the A / D conversion units 32 and 40 corresponding to the I-phase component and the Q-phase component, respectively. A reference adjustment unit 86 for determining a reference value of the / D conversion units 32 and 40, and a circuit between the direct wave extraction units 52 and 58 corresponding to the I-phase component or the Q-phase component and the reference adjustment unit 86, or A switch 88 that shuts off, a first circuit that supplies an output from the I-phase direct wave extraction unit 52 provided corresponding to the I-phase component to the switch 88, and a Q-phase component corresponding to the first circuit. The output from the Q-phase direct wave extraction unit 58 provided is connected to the switch 8 Since the second circuit switching unit 90 that switches between the second circuit and the second circuit to be supplied to the device is directly connected to the I-phase component and the Q-phase component by a simpler circuit than the above-described RFID tag communication device 12. Wave components can be detected.

  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 direct wave detection units 28 and 36 are provided with the direct wave extraction units 52 and 58 as differential amplifiers, but the present invention is not limited thereto. For example, the direct wave component can also be extracted by a configuration in which negative polarity is added to the received signal.

Further, in the above-described embodiment, the control unit 46 generates a cancel signal generated by the cancel signal generation unit 22 so that the calculated value m ₃ calculated by the signal processing unit 44 is as small as possible. The phase and / or amplitude is controlled. For example, in a wireless communication apparatus including a low noise amplifier (LNA), the phase of the cancel signal is maximized so that the output of the low noise amplifier is maximized. And / or controlling the amplitude.

  In the above-described embodiment, the RFID tag communication device 12 and the like provided with the antenna 16 for transmission and reception are illustrated. However, the present invention is applied to a wireless communication device provided with a transmission antenna and a reception antenna, respectively. Needless to say.

  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 communication apparatus of this invention is used suitably. It is a figure explaining the structure of the radio | wireless tag communication apparatus which is one Example of the radio | wireless communication apparatus of this invention. It is a figure explaining the structure of the RFID circuit element with which the RFID tag which is a communication object of the RFID tag communication apparatus of FIG. 2 was equipped. 3 is a flowchart illustrating a main part of direct wave cancellation control by a signal processing unit and a control unit of the RFID tag communication apparatus of FIG. 2. It is a figure explaining the structure of the radio | wireless tag communication apparatus which is the other Example of the radio | wireless communication apparatus of this invention. 6 is a flowchart illustrating a main part of direct wave cancellation control by a signal processing unit and a control unit of the RFID tag communication apparatus of FIG. 5.

Explanation of symbols

12, 84: RFID tag communication device (wireless communication device)
14: Wireless tag (communication target)
16: Antenna (transmitting antenna, receiving antenna)
22: Cancel signal generator 24: Cancel signal synthesizer 26: Quadrature demodulator 28: I-phase direct wave detector 32: I-phase A / D converter 34: I-phase circuit switching unit 36: Q-phase direct wave detector 40 : Q phase A / D conversion unit 42: Q phase circuit switching unit 44: Signal processing unit 48: Variable phase shifter (cancellation phase control unit)
50: Variable attenuator (cancellation amplitude controller)
52: I-phase direct wave component extraction unit 54: I-phase reference adjustment unit 56: I-phase switch 58: Q-phase direct wave component extraction unit 60: Q-phase reference adjustment unit 62: Q-phase switch 64: storage unit 86: Reference adjustment unit 88: Switch 90: Second circuit switching unit

Claims (14)

A wireless communication apparatus that transmits a transmission signal from a transmission antenna and receives a reply signal returned from a communication target according to the transmission signal by a reception antenna and communicates information with the communication target. And
A direct wave detection unit for detecting a direct wave component from a transmission side in a reception signal received by the reception antenna;
A signal processing unit for processing a direct wave component detected by the direct wave detection unit;
An A / D converter that digitally converts a received signal received by the receiving antenna or a direct wave component detected by the direct wave detector and supplies the signal to the signal processor;
A cancel signal generating unit for generating a cancel signal for suppressing a direct wave component from the transmission side in the received signal based on a processing result by the signal processing unit;
And a cancel signal combining unit for combining the signal received by the cancellation cancellation signal generated by the signal generating unit and the reception antenna, possess,
The direct wave detector is
A direct wave extracting unit that extracts a direct wave component in the received signal according to a difference between the received signal received by the receiving antenna and a predetermined reference signal;
A reference adjustment unit provided between the direct wave extraction unit and the A / D conversion unit to determine a reference value of the A / D conversion unit;
A switch for connecting or disconnecting a circuit between the direct wave extraction unit and the reference adjustment unit;
Wireless communication device, characterized in that the, is intended to include.   The wireless communication apparatus according to claim 1, wherein the cancel signal generation unit includes a cancel phase control unit that controls a phase of the cancel signal and / or a cancel amplitude control unit that controls an amplitude.   A first circuit that supplies a reception signal received by the reception antenna to the signal processing unit; and a second circuit that supplies a direct wave component detected by the direct wave detection unit to the signal processing unit. The wireless communication device according to claim 1, further comprising a circuit switching unit for switching. The signal processing unit is configured to determine the phase and / or amplitude of the cancellation signal based on a reference value and an actual output value in digital conversion of the direct wave component by the A / D conversion unit from a predetermined relationship. Calculates the calculated value,
The wireless communication device according to any one of claims 1 to 3, wherein the cancel signal generation unit controls the phase and / or amplitude of the cancel signal based on the calculated value based on a predetermined relationship. The signal processing unit includes a storage unit that stores a signal supplied from the A / D conversion unit, and the storage unit is configured to perform digital conversion of the direct wave component by the A / D conversion unit. The wireless communication apparatus according to claim 4 , wherein the reference value is stored in Any of the wireless communication device of claims 1-5 and has a quadrature demodulator for demodulating the signal received by the receiving antenna as I-phase component and Q-phase components orthogonal to each other. The radio communication apparatus according to claim 6 , comprising the direct wave detection unit, an A / D conversion unit, and a circuit switching unit corresponding to the I-phase component and the Q-phase component demodulated by the quadrature demodulation unit. Corresponding to the I-phase component and Q-phase component demodulated by the quadrature demodulation unit, the direct wave extraction unit, the A / D conversion unit, and the circuit switching unit,
A reference adjustment unit that is provided between the direct wave extraction unit and the A / D conversion unit corresponding to each of the I-phase component and the Q-phase component and determines a reference value of the A / D conversion unit;
A switch for connecting or disconnecting a circuit between the direct wave extraction unit corresponding to the I-phase component or the Q-phase component and the reference adjustment unit;
A first circuit for supplying an output from the direct wave extraction unit provided corresponding to the I-phase component to the switch; and an output from the direct wave extraction unit provided corresponding to the Q-phase component. The wireless communication apparatus according to claim 6 , further comprising a second circuit switching unit that switches between the second circuit to be supplied to the switch. The signal processing unit has a reference in digital conversion by the A / D conversion unit based on a predetermined relationship for each of the I-phase component and the Q-phase component supplied via the direct wave detection unit and the A / D conversion unit. any of the wireless communication device of claims 6 and calculates the calculated value for the values and on the basis of the actual output values for determining the phase and / or amplitude of the cancellation signal 8. The signal processing unit includes a reference value and an actual output value in digital conversion by the A / D conversion unit for each of the I-phase component and the Q-phase component supplied via the direct wave detection unit and the A / D conversion unit. The wireless communication device according to claim 9 , wherein the difference is a square root of the sum of the squares of the differences corresponding to the I-phase component and the Q-phase component. The wireless communication apparatus according to claim 10 , wherein the cancellation signal generation unit controls the phase and / or amplitude of the cancellation signal so that the calculated value calculated by the signal processing unit is as small as possible. The cancellation signal generation unit is configured to calculate a difference between a reference value and an actual output value in the digital conversion by the A / D conversion unit calculated by the signal processing unit corresponding to the I phase component, and a Q phase component. Controlling the phase and / or amplitude of the cancellation signal based on the larger of the difference between the reference value and the actual output value in the digital conversion by the A / D conversion unit calculated correspondingly The wireless communication device according to claim 9 . 2. The signal processing unit performs processing of the direct wave component on a received signal received by the receiving antenna according to a carrier wave transmitted from the transmitting antenna or a signal including a predetermined command. Any one of 12 to 12 . The communication target is a wireless tag capable of writing and / or reading information via wireless communication,
The wireless communication device transmits a predetermined transmission signal to the wireless tag by a transmission antenna and receives a return signal returned from the wireless tag in response to the transmission signal by the reception antenna. in any of the wireless communication apparatus according to claim 1 to 13 is a radio tag communication apparatus for communicating information between the wireless tag.

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