JP4561496B2 - Wireless receiver - Google Patents

Description

  The present invention relates to an improvement of a radio reception apparatus including a plurality of reception antenna elements for receiving a signal transmitted from a predetermined communication target.

  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.

  A plurality of antenna elements for receiving signals transmitted from the wireless tag in order to perform communication in accordance with the direction of the wireless tag to be communicated as one aspect of the wireless receiving device incorporated in such wireless tag communication And receiving directivity is controlled by synthesizing reception signals received by the plurality of antenna elements. For example, this is the wireless device described in Patent Document 1. According to this radio apparatus, since the array antenna includes a plurality of antenna elements, and an adaptive processing unit that multiplies each received signal received by the plurality of antenna elements by a weight, The directivity can be suitably determined, and a signal transmitted from a wireless tag that is a communication target can be suitably received.

JP 2003-283411 A

  However, in the conventional technique, it is necessary to provide the same number of receiving circuits as the plurality of antenna elements. In addition, a cancel circuit for removing a sneak signal from the transmission side on the reception side needs to be provided corresponding to each of the plurality of antenna elements, resulting in a disadvantage that the configuration is complicated and the cost is increased. That is, there has been a demand for the development of a radio receiving apparatus that can suitably perform directivity control with the simplest possible configuration.

  The present invention has been made against the background of the above circumstances, and an object of the present invention is to provide a radio receiving apparatus capable of suitably performing directivity control with the simplest possible configuration.

  In order to achieve such an object, the gist of the present invention is a wireless reception device that receives a signal transmitted from a predetermined communication target and performs reception processing, and the signal transmitted from the communication target A single reference antenna element and a plurality of reception antenna elements for receiving a signal, an antenna switching unit for selectively switching a reception antenna element for receiving the signal among the plurality of reception antenna elements, and the reference antenna element A reference reception signal processing unit that processes a received reference reception signal, a selection reception signal processing unit that processes a selection reception signal received by a reception antenna element selected by the antenna switching unit, and the reference reception signal processing unit And a reception information storage unit for storing the reference reception signal and the selection reception signal processed by the selective reception signal processing unit, and the reception information storage unit. And a corresponding selection stored in the reception information storage unit according to a correction amount of each reference reception signal when the signal synchronization unit synchronizes the plurality of reference reception signals. A reception signal correction unit that corrects a reception signal, and a directivity control unit that controls communication directivity with the communication target using a plurality of selection reception signals corrected by the reception signal correction unit, It is characterized by having.

  In this case, a single reference antenna element and a plurality of receiving antenna elements for receiving a signal transmitted from the communication target, and a receiving antenna element for receiving the signal among the plurality of receiving antenna elements are provided. An antenna switching unit that selectively switches, a reference reception signal processing unit that processes a reference reception signal received by the reference antenna element, and a selection reception signal that is received by the reception antenna element selected by the antenna switching unit A selected reception signal processing unit, a reception information storage unit that stores the reference reception signal and the selection reception signal processed by the reference reception signal processing unit and the selection reception signal processing unit, and a plurality of information stored in the reception information storage unit Depending on the signal synchronization unit that synchronizes the reference received signal and the correction amount of each reference received signal when synchronized by the signal synchronizing unit Communication between a reception signal correction unit that corrects corresponding selection reception signals stored in the reception information storage unit, and the communication target using a plurality of selection reception signals corrected by the reception signal correction unit In addition to having a directivity control unit that controls directivity, in addition to being able to reduce the number of receiving circuits to be provided by performing a receiving operation while switching the receiving antenna element that receives the signal, By using the reference reception signal received by the reference antenna element, it is possible to suitably synchronize the reception signals received at individual reception timings by the plurality of reception antenna elements. That is, it is possible to provide a radio reception apparatus that can suitably perform directivity control with the simplest possible configuration.

  Here, it is preferable that the signal synchronization unit determines a correction amount of each reference reception signal so that the correlation of the reference reception signals at each reception timing is maximized. In this way, the plurality of reference received signals can be accurately synchronized in a practical manner.

  Preferably, the signal synchronization unit determines a correction amount of each reference reception signal so that a start position of the communication signal of the reference reception signal at each reception timing matches. In this way, the plurality of reference reception signals can be easily synchronized in a practical manner.

  Preferably, the reception signal correction unit corrects the delay amount of each corresponding selection reception signal based on a delay when synchronizing the plurality of reference reception signals. In this way, the plurality of selective reception signals can be synchronized in a practical manner.

  Preferably, the reception signal correction unit corrects the amplitudes of the corresponding selection reception signals based on the amplitudes when the plurality of reference reception signals are synchronized. In this way, even if there is a difference in the communication signal intensity transmitted from the communication target at each reception timing, the amplitude ratios of the plurality of selected reception signals can be adjusted in a practical manner.

  Preferably, the directivity control unit controls communication directivity with the communication target by phased array processing. In this way, it is possible to control the reception directivity of the wireless receiver in the previous period in a practical manner.

  Preferably, the directivity control unit controls communication directivity with the communication target by adaptive array processing. In this way, it is possible to efficiently receive a reception signal from the communication target.

  Preferably, the communication target transmits the same signal a plurality of times, and the antenna switching unit is configured such that each signal transmitted from the communication target is received by a single receiving antenna element. To switch to. In this way, it is possible to obtain a reception result equivalent to the case where signals transmitted from the communication target are simultaneously received by a plurality of receiving antenna elements.

  Preferably, the reception information storage unit stores phase information of the reference reception signal and the selection reception signal processed by the reference reception signal processing unit and the selection reception signal processing unit. In this way, in addition to being able to execute reception processing such as direction detection of the communication target based on such phase information, the amount of information to be stored compared to storing the reference reception signal and the selected reception signal itself Is less.

  Preferably, at least three receiving antenna elements are provided. In this way, the reception directivity from the communication target can be controlled by a necessary and sufficient number of reception antenna elements.

  Preferably, a plurality of receiving circuits for processing a reception signal received by the receiving antenna element are provided, and the number of the receiving circuits is smaller than the number of the plurality of receiving antenna elements. In this way, the number of receiving circuits that should be provided in the wireless receiving device can be reduced.

  In addition, preferably, a single reception circuit for processing a reception signal received by the reception antenna element is provided. In this way, the number of receiving circuits to be provided in the radio receiving apparatus can be minimized.

  Preferably, the communication target is a wireless tag capable of returning a response signal in response to a predetermined transmission signal, and the wireless reception device includes a wireless transmission device that transmits a predetermined transmission signal to the wireless tag. The wireless tag communication apparatus that reads and / or writes information from and to the wireless tag by performing communication with the wireless tag. In this way, a wireless receiver capable of performing directivity control with the simplest possible configuration can be applied to the wireless tag communication device that communicates information with the wireless tag. In addition, communication with the wireless tag has a smaller amount of communication data than normal communication, and even if the same communication is performed multiple times, the time required for the communication can be shortened, and all timing control related to communication is performed on the wireless tag communication device side. Therefore, it is suitable for this system.

  Preferably, the wireless transmission device transmits the transmission signal so that the same return signal is replied a plurality of times from the wireless tag that is a communication target, and the antenna switching unit includes the wireless switching device. Switching is performed so that a reply signal returned from the tag is received by each single receiving antenna element. In this way, it is possible to obtain a reception result equivalent to the case where response signals returned from the wireless tag are simultaneously received by a plurality of receiving antenna elements.

  Preferably, the wireless transmission device can selectively transmit a transmission signal based on a plurality of types of transmission commands, and the wireless reception device transmits a transmission signal transmitted to the wireless tag. In accordance with a corresponding transmission command, a first reception process using a selective reception signal received by the plurality of reception antenna elements and a second reception process using a reference reception signal received by the reference antenna element It can be switched. In this way, for example, in communication corresponding to a transmission command that requires relatively high reception accuracy, such as “Scroll ID” that is a command for requesting a reply of an ID (identification number) to a specific RFID tag element, the plurality of For example, "PING" is a command for checking the presence or absence of a wireless tag in the communication range, and the single reference antenna element is used for communication that does not require so high reception accuracy. By using the reception processing, the communication time can be shortened as much as possible while guaranteeing the required reception accuracy.

  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 communication system 10 in which the wireless reception apparatus of the present invention is preferably used. The communication system 10 includes a wireless tag communication device 12 in which the wireless reception device of the present invention is incorporated, and a single or plural (single in FIG. 1) wireless tags 14 that are communication targets of the wireless 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 apparatus 12 toward the radio tag 14, a predetermined information signal (data) is received in the radio tag 14 that has received the interrogation wave F _c. Thus, the interrogation wave F _c is modulated and returned as a response wave F _r (reply signal) to the RFID tag communication apparatus 12. Then, when the response wave F _r is received by the RFID tag communication apparatus 12, information is communicated between the RFID tag communication apparatus 12 and the RFID tag 14, and information is read from the RFID tag 14. And / or writing is performed.

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 communicates information with the wireless tag 14 in order to read / write information with respect to the wireless tag 14 and detect the direction of the wireless tag 14. A digital signal processor (DSP) 16 that performs digital signal processing such as outputting the transmission signal as a digital signal or demodulating a return signal from the wireless tag 14, and output by the DSP 16. and the transmission signal and the transmission circuit 18 to be transmitted as interrogating wave F _c into an analog signal, a response wave F _r transmitted back from the radio tag 14 in response to the interrogating wave F _c which is transmitted by the transmission circuit 18 The receiving circuit 20 is configured to receive, convert to a digital signal, and supply the digital signal to the DSP 16.

The transmission circuit 18 generates a carrier wave of the interrogation wave F _c and a predetermined transmission information signal (transmission command) supplied from the DSP 16 to the carrier wave generated by the carrier wave generation unit 22. A transmission signal generation unit 24 that combines and generates the transmission signal; a transmission antenna element 26 for transmitting the transmission signal generated by the transmission signal generation unit 24 toward the wireless tag 14 as the interrogation wave F _c ; Are provided. The receiving circuit 20 receives a plurality (three in FIG. 2) of receiving response waves F _r returned from the wireless tag 14 in response to the interrogation wave F _c transmitted by the transmission circuit 18. Antenna elements 28a, 28b, and 28c (hereinafter simply referred to as reception antenna element 28 unless otherwise distinguished) and reception antenna element 28 that receives response wave _Fr from radio tag 14 among these reception antenna elements 28. An antenna switching unit 30 that selectively switches between and a first cancellation process that is a carrier cancellation circuit for removing a sneak signal generated in the reception antenna element 28 due to a transmission signal transmitted from the transmission antenna element 26 Unit 32, a local oscillator 34 for generating a predetermined local oscillation signal, and the first cancellation processing unit 32 cancel the processing. The first intermediate signal is obtained by multiplying the selected received signal (referred to as a received signal selectively received by any of the receiving antenna elements 28, the same in the following description) by the local signal generated by the local oscillator 34. A first intermediate signal generation unit 36 to be generated, a selective reception signal A / D converter 38 that converts the first intermediate signal generated by the first intermediate signal generation unit 36 into a digital signal and supplies the digital signal to the DSP 16, and the transmission A single reference antenna element 40 for receiving a response wave F _r returned from the wireless tag 14 in response to the interrogation wave F _c transmitted by the circuit 18, and a transmission signal transmitted from the transmission antenna element 26 A second cancellation processing unit 42 which is a carrier cancellation circuit for removing a sneak signal generated in the reference antenna element 40 due to The reference received signal canceled by the second cancel processing unit 42 (referred to as a received signal received by the reference antenna element 40, the same in the following description) is multiplied by the local signal generated by the local oscillator 34. A second intermediate signal generation unit 44 for generating a second intermediate signal, and a reference reception signal A / D which is converted into a digital signal by the second intermediate signal generated by the second intermediate signal generation unit 44 and supplied to the DSP 16 The converter 46 is provided.

  The first cancel processing unit 32 includes a first cancel signal phase control unit 48 that controls the phase of the carrier wave generated and distributed by the carrier wave generation unit 22, and a first cancel signal amplitude control unit 50 that controls the amplitude. And a first cancel signal phase control unit for generating a first cancel signal for removing a sneak signal generated in the reception antenna element 28 due to a transmission signal transmitted from the transmission antenna element 26. 48 and the first cancel signal amplitude control unit 50 generate the carrier wave from the carrier wave. The first cancel signal output from the first cancel signal amplitude control unit 50 is multiplied by the selection reception signal received by the reception antenna element 28 via the first cancellation signal synthesis unit 52, and the selection reception signal is added to the selection reception signal. The included sneak signal from the transmission side is canceled by canceling out the first cancel signal. The second cancellation processing unit 42 includes a second cancellation signal phase control unit 54 that controls the phase of the carrier wave generated and distributed by the carrier wave generation unit 22, and a second cancellation signal amplitude control that controls the amplitude. A second cancellation signal for removing a sneak signal generated in the reference antenna element 40 due to a transmission signal transmitted from the transmission antenna element 26. It is generated from the carrier by the control unit 54 and the second cancel signal amplitude control unit 56. The second cancellation signal output from the second cancellation signal amplitude control unit 56 is multiplied by the reference reception signal received by the reference antenna element 40 via the second cancellation signal synthesis unit 58, and the reference reception signal is added to the reference reception signal. The included sneak signal from the transmission side is canceled by canceling out the second cancel signal.

  The DSP 16 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. An antenna switching control unit 62, a selective reception signal processing unit 64, a reference reception signal processing unit 66, a reception information storage unit 68, a signal synchronization unit 70, a reception signal correction unit 72, a directivity control unit 74, and a reception signal processing unit 76. It is functionally provided, and supplies a predetermined transmission information signal (transmission command) to the transmission signal generation unit 24, controls the switching operation by the antenna switching unit 30, and the first cancel processing unit 32 and the first 2 The carrier canceling operation by the cancel processing unit 42 is controlled or supplied from the selective reception signal A / D converter 38. That executes the digital signal processing such as demodulating a reply signal from the wireless tag 14 by processing the reference reception signal supplied from the selection received signal and the reference receiving signal A / D converter 46. Here, the transmission circuit 18 and the transmission information generation unit 24 constitute a wireless transmission device that transmits a predetermined transmission signal to the wireless tag 14, and the reception circuit 20, the antenna switching control unit 62, and the selective reception signal processing unit 64. The reference received signal processing unit 66, the received information storage unit 68, the signal synchronization unit 70, the received signal correction unit 72, the directivity control unit 74, and the received signal processing unit 76 constitute the radio receiving apparatus of this embodiment. .

FIG. 3 is a diagram illustrating the configuration of the RFID circuit element 80 provided in the RFID tag 14. As shown in FIG. 3, the RFID circuit element 80 has an antenna unit 82 for transmitting and receiving signals to and from the RFID tag communication device 12, and processes a signal received by the antenna unit 82. And an IC circuit part 84 for the purpose. The IC circuit part 84 comprises a rectification part 86 that rectifies the interrogation wave F _c from the radio tag communication apparatus 12 received by the antenna unit 82, the energy of the interrogation wave rectified F _c by the rectifying unit 86 Functions as a power supply unit 88 for accumulation, a clock extraction unit 90 that extracts a clock signal from the carrier wave received by the antenna unit 82 and supplies the clock signal to the control unit 96, and an information storage unit that can store a predetermined information signal The RFID circuit element 80 via the memory unit 92, the modulation / demodulation unit 94 connected to the antenna unit 82 for modulating and demodulating the signal, the rectification unit 86, the clock extraction unit 90, the modulation / demodulation unit 94, and the like. And a control unit 96 for controlling the operation of the function. The control unit 96 performs control for storing the predetermined information in the memory unit 92 by communicating with the RFID tag communication device 12, and the modulation / demodulation unit 94 receives the interrogation wave F _c received by the antenna unit 82. Then, basic control such as control for reflecting and returning the response wave _Fr as the response wave _Fr is executed based on the information signal stored in the memory unit 92.

Returning to FIG. 2, the transmission information generator 60 functionally provided in the DSP 16 generates a predetermined transmission information signal for generating a transmission signal by modulating the carrier wave generated by the carrier wave generator 22. And supplied to the transmission signal generator 24. The transmission information signal is, for example, a transmission command such as “Scroll ID” which is a command for requesting a response to a specific wireless tag 14 or “PING” which is a command for checking the presence or absence of the wireless tag 14 in the communication range. The transmission command generated by the transmission information generation unit 60 is sent to the transmission signal generation unit 24, and the transmission signal generation unit 24 multiplies the transmission command by the carrier wave supplied from the carrier wave generation unit 22. It is modulated Te is, transmission signal including the transmission command is transmitted to the wireless tag 14 as interrogating wave F _c from the transmitting antenna element 26. In this way, the wireless tag communication device 12 preferably selectively transmits transmission signals based on a plurality of types of transmission commands to the wireless tag 14 via the transmission information generation unit 60. In addition, preferably, a transmission signal having the same pattern, that is, a transmission signal including the same transmission command is transmitted via the transmission information generation unit 60 so that the same reply signal is replied a plurality of times from the wireless tag 14 to be communicated. Is sent multiple times.

The antenna switching control unit 62 selectively switches the receiving antenna element 28 that receives the response wave F _r from the wireless tag 14 among the plurality of receiving antenna elements 28 via the antenna switching unit 30. That is, the reception antenna element 28 that outputs a reception signal to the first cancellation processing unit 32 is selectively switched. Preferably, a single receiving antenna element 28 that receives the response wave F _r from the wireless tag 14 is selected from the plurality of receiving antenna elements 28. Preferably, the response wave F _r transmitted (returned) a plurality of times from the wireless tag 14 to be communicated in response to a transmission signal including the same transmission command transmitted a plurality of times via the transmission information generating unit 60. Are selectively switched among the plurality of reception antenna elements 28 so that the reception antenna elements 28 are received by different reception antenna elements 28, respectively. That is, according to the transmission timing of the interrogating wave F _c which is transmitted by the transmission circuit 18 selectively switches the receiving antenna element 28 used in the reception of the reply signal returned to its interrogating wave F _c.

  The selective reception signal processing unit 64 processes the selective reception signal supplied from the selective reception signal A / D converter 38 and stores the processed signal in the reception information storage unit 68. Preferably, the phase information of the selective reception signal supplied from the selective reception signal A / D converter 38 is extracted and stored in the reception information storage unit 68. The reference reception signal processing unit 66 processes the reference reception signal supplied from the reference reception signal A / D converter 46 and stores the processed signal in the reception information storage unit 68. Preferably, the phase information of the reference reception signal supplied from the reference reception signal A / D converter 46 is extracted and stored in the reception information storage unit 68.

The reception information storage unit 68 stores the selective reception signal received by any one of the reception antenna elements 28 supplied from the selective reception signal processing unit 64 or the phase information of the selective reception signal. Further, the reference reception signal received by the reference antenna element 40 supplied from the reference reception signal processing unit 66 or the phase information of the reference reception signal is stored. FIG. 4 is a diagram illustrating received information stored in the received information storage unit 68 for each reception timing. As shown in FIG. 4, the reception information storage unit 68 includes reception information corresponding to the timing n, timing n + 1, with respect to the selected reception signal received by the reception antenna element 28 selected by the antenna switching control unit 62. , Received information corresponding to timing n + 2, and so on are stored individually. In addition, with respect to the reference reception signal received by the reference antenna element 40, reception information is stored for each timing. In FIG. 4, the received information corresponding to timing n is received by the receiving antenna element 28a, and the received information corresponding to timing n + 1 is received by the receiving antenna element 28b, and at timing n + 2. Corresponding reception information is information received by the reception antenna element 28c. Since the wireless tag 14 to be communicated returns a response wave F _r according to the interrogation wave F _c transmitted from the transmission antenna element 26, the reception antenna element for reception according to the transmission timing. By selectively switching 28, response waves F _r replied a plurality of times from the wireless tag 14 to be communicated are received by different receiving antenna elements 28. The response wave F _r is also received by the reference antenna element 40 at the same time. Thus, the reception information regarding the selected reception signal received by the different reception antenna elements 28 and the reference reception received by the reference antenna element 40 are obtained. The received information related to the signal is associated and stored in the received information storage unit 68 as shown in FIG.

The signal synchronization unit 70 synchronizes a plurality of reference reception signals stored in the reception information storage unit 68. Preferably, the correction amount of each reference received signal is determined so that the correlation (correlation function) of the reference received signal at each reception timing controlled by the antenna switching control unit 62 is maximized. If the correlation of the reference reception signals at a plurality of reception timings is large, it is considered that the reference reception signals are synchronized. Therefore, the correction amount of each reference reception signal is determined so as to maximize the correlation. In this correction, for example, each reference reception signal is delayed by a predetermined amount in order to synchronize the reference reception signals at a plurality of reception timings. The correction amount is used when synchronizing a plurality of reference reception signals. Corresponds to the delay amount. Here, synchronization may be obtained from the entire waveform of the reference reception signal, but it is sufficient that synchronization can be achieved at least at the beginning. Therefore, the signal synchronization unit 70 preferably corrects the correction amount of each reference reception signal so that the start positions of the communication signals of the reference reception signal at the respective reception timings controlled by the antenna switching control unit 62 coincide. To decide. The start position of the communication signal of the reference reception signal is, for example, the end position of the preamble of the reference reception signal (a signal for a stable time added to the head of the transmission signal), in other words, a substantial communication part. Corresponds to the starting position of. Preferably, when synchronizing from the entire waveform, the delay amount is determined from the start timing of each received signal, and the received frequency is corrected from the end timing of the received signal to achieve synchronization. In this case, even when the modulation frequency of the response wave _Fr from the wireless tag 14 changes at different timings n and n + 1, a correct correlation can be obtained.

The reception signal correction unit 72 corrects the corresponding selected reception signal stored in the reception information storage unit 68 according to the correction amount of each reference reception signal when the signal synchronization unit 70 synchronizes. FIG. 5 is a diagram for explaining the correction of the selected reception signal at each reception timing by the reception signal correction unit 72. As shown in FIG. 5, the reception signal correction unit 72 preferably delays the corresponding selection reception signal based on the delay when the signal synchronization unit 70 synchronizes the plurality of reference reception signals. Correct the time. As described above, the reception information storage unit 68 stores the selected reception signal received by the reception antenna element 28 selected by the antenna switching unit 30 and the reference reception received by the reference antenna element 40 at each reception timing. Signals are stored in association with each other. Since the reference reception signal and the selection reception signal that are associated with each other correspond to the same response wave F _r , it can be said that the reception timing is substantially the same and the reception content is equivalent. Therefore, the correction amount (delay) determined for synchronizing the reference reception signal at each reception timing by the signal synchronization unit 70 is used as the correction amount for synchronizing the selected reception signal at each reception timing as it is. Can do it. In FIG. 5, in synchronization with the timing of the reference reception signal, the timing n + 1 signal is advanced by Δt and the timing n + 1 signal is advanced by 0.5Δt with respect to the timing n signal. In addition, the reception signal correction unit 72 preferably corrects the amplitude of the corresponding selection reception signal based on the amplitude when the signal synchronization unit 70 synchronizes the plurality of reference reception signals. Since the reference received signal and the selected received signal that are associated with each other are equivalent, the amplitude of each selected received signal can be corrected according to the size of the reference received signal.

  The directivity control unit 74 uses a plurality of selected reception signals corrected by the reception signal correction unit 72 to communicate with the wireless tag 14 that is a communication target, that is, a response signal from the wireless tag 14. Controls reception directivity. Preferably, communication directivity with the wireless tag 14 is controlled by a phased array process in which the phase of each selected reception signal is controlled by multiplying a predetermined PAA weight. Preferably, communication directivity with the wireless tag 14 is controlled by adaptive array processing that controls the phase and amplitude of each selected reception signal by multiplying a predetermined AAA weight.

The reception signal processing unit 76 processes a plurality of selective reception signals whose directivity is controlled by the directivity control unit 74. For example, the plurality of selective reception signals are combined, subjected to demodulation using the AM method, decoding using the FSK method, and the like, and then a signal related to the modulation by the wireless tag 14 is read. In this manner, information is communicated with the wireless tag 14 that is a communication target, and for example, the relative direction or position of the wireless tag 14 can be detected. As described above, in the wireless tag communication device 12 according to the present embodiment, the antenna switching control unit 62 selects the reception antenna element 28 that receives the response wave F _r from the wireless tag 14 among the plurality of reception antenna elements 28. The received information received by the receiving antenna element 28 is temporarily stored in the received information storage unit 68, and then the plural types of selected received information are read out and processed by the received signal processing unit 76. With the configuration, as shown in FIG. 2, it is sufficient to provide a first cancellation processing unit 32 that is fewer or more in number than the reception antenna element 28. Similarly, the first intermediate signal generation unit 36, the selective reception signal A / D converter 38, and the like can also be fewer or singular than the reception antenna element 28. That is, in order to process a selective reception signal received by the reception antenna element 28, it is only necessary to provide a reception circuit 20 having a smaller number or a single number than the number of the reception antenna elements 28. Suitable communication with a certain wireless tag 14 can be realized.

  Here, the wireless tag communication device 12 is preferably configured to receive the plurality of receptions in response to a transmission command corresponding to a transmission signal transmitted toward the wireless tag 14 generated by the transmission information generation unit 60. The first reception process using the selective reception signal received by the antenna element 28 and the second reception process using only the reference reception signal received by the reference antenna element 40 can be switched. In communication with the wireless tag 14, the reception accuracy varies depending on the content of the communication. For example, in communication corresponding to “Scroll ID” which is a command for requesting a response to a specific wireless tag 14, it is necessary to surely communicate with the wireless tag 14, so that relatively high reception accuracy is obtained. However, in communication corresponding to “PING” or the like, which is a command for checking the presence / absence of the wireless tag 14 in the communication area, it is only necessary to receive a reply from within the area, and so high reception accuracy is required. Absent. Preferably, the RFID tag communication device 12 preferably includes the plurality of reception antenna elements when communication corresponding to a transmission command generated by the transmission information generation unit 60 requires relatively high reception accuracy. The first reception process using the selective reception signal received by the reference numeral 28 is performed, and when the high reception accuracy is not required, the second reception process using the reference reception signal received by the reference antenna element 40 is performed. . In the process using the reference received signal, the control by the signal synchronizer 70 and the control by the received signal corrector 72 are not performed, so that the communication time can be ensured while guaranteeing the required reception accuracy. It can be shortened as much as possible.

  FIG. 6 is a flowchart for explaining information communication control with the wireless tag 14 by the DSP 16 of the wireless tag communication device 12 and is repeatedly executed at a predetermined cycle.

First, in step (hereinafter, step is omitted) SA1, the variable i is set to zero. Next, in SA2, the setting of the first cancel processing unit 32 is set to a value corresponding to the receiving antenna element 28 corresponding to the variable i. Next, in SA3 corresponding to the operation of the antenna switching control unit 62, the antenna switching unit so that the received signal received by the receiving antenna element 28 corresponding to the variable i is supplied to the first cancellation processing unit 32. 30 is switched. Next, in SA4 corresponding to the operations of the transmission information generation unit 60, the selective reception signal processing unit 64, and the reference reception signal processing unit 66, the interrogation wave F _c is transmitted from the transmission antenna element 26, and the interrogation wave F _The response wave F _r returned from the wireless tag 14 according to _c is received by the receiving antenna element 28 corresponding to the variable i. Then, the signal is input to the DSP 16 through the first cancel processing unit 32, the first intermediate signal generation unit 36, and the selective reception signal A / D converter 38. At the same time, the response wave F _r is received by the reference antenna element 40 and passes through the second cancellation processing unit 42, the second intermediate signal generation unit 44, and the reference reception signal A / D converter 46 to the DSP 16. Entered. Next, in SA5 corresponding to the operation of the reception information storage unit 68, the selective reception signal received by the reception antenna element 28 supplied from the selective reception signal processing unit 64 or the phase information thereof is stored. A reference reception signal received by the reference antenna element 40 supplied from the reference reception signal processing unit 66 or phase information thereof is stored. Next, in SA6, it is determined whether or not the variable i is less than N-1. If the determination at SA6 is affirmative, 1 is added to the variable i at SA7, and then the processing after SA2 is executed again. If the determination at SA6 is negative, the signal synchronization is performed. In SA8 corresponding to the operation of the unit 70, with respect to the plurality of reference received signals stored in the received information storage unit 68, the correction amount of each reference received signal so that the correlation (correlation function) at each reception timing is maximized Is determined. Next, in SB, after the received signal synthesis control shown in FIG. 7 is executed, this routine is terminated.

  FIG. 7 is a flowchart for explaining the combination control of the selective reception information received by the plurality of reception antenna elements 28, which is a part of the information communication control with the wireless tag 14 shown in FIG.

  First, in SB1, the variable i is set to 0. Next, at SB2, the selected reception information stored in the reception information storage unit 68 corresponding to the variable i is read. Next, in SB3, in order to match the communication start position of the selective reception information read out in SB2 with the communication start position of other selective reception signals, each reference reception signal when synchronized in SA8 described above For example, the delay amount of the selected reception signal is corrected based on the delay of the reference reception signal received at the same reception timing. Next, in SB3 ′, the amplitude of the selected reception signal corrected in SB2 is corrected based on the amplitude of each reference reception signal when synchronization is established. Next, in SB4, it is determined whether or not the variable i is less than N-1. If the determination of SB4 is affirmed, in SB5, 1 is added to the variable i, and then the processes after SB2 are executed again. However, if the determination of SB4 is negative, all selective receptions are performed. Signal reading and head alignment are complete. In other words, at this time, a received signal equivalent to that simultaneously communicated by the plurality of receiving antennas 28 is prepared. Next, using this received signal, in SB 6 corresponding to the operation of the directivity control unit 74, weights given to each of a plurality of types of reception information subjected to head alignment are calculated, and the plurality of types of selective reception are calculated. Signal directivity control is performed. Next, in SB7, a plurality of types of selective reception information whose directivity is controlled in SB6 are combined. Next, in SB8, the combined signal synthesized in SB7 is AM demodulated by AM method, the demodulated signal is FM-decoded, and an information signal related to the modulation by the wireless tag 14 is read out, and then, FIG. It is returned to the control shown. In the above control, SB7 and SB8 correspond to the operation of the reception signal processing unit 76.

  Here, the reception process switching control as shown in FIG. 8 may be performed as the upper process of the information communication control with the wireless tag 14 shown in FIG. In the control shown in FIG. 8, first, in S1, it is determined whether the transmission command generated by the transmission information generation unit 60 is “Scroll ID” or “PING”. If it is determined in S1 that the transmission command generated by the transmission information generation unit 60 is “Scroll ID”, information communication with the wireless tag 14 shown in FIG. 6 is performed in SA. After the control is executed, this routine is terminated. When it is determined in S1 that the transmission command generated by the transmission information generation unit 60 is “PING”, the reference antenna is determined in S2. Only the reception process using the reference reception signal received by the element 40 is executed, and this routine is terminated.

  Thus, according to the present embodiment, a single reference antenna element 40 and a plurality of reception antenna elements 28 for receiving a signal returned from the wireless tag 14 that is a communication target, and the plurality of reception antennas. An antenna switching unit 30 that selectively switches the receiving antenna element 28 that receives the signal among the elements 28; a reference received signal processing unit 66 (SA4) that processes a reference received signal received by the reference antenna element 40; The selective reception signal processing unit 64 (SA4) that processes the selective reception signal received by the reception antenna element 28 selected by the antenna switching unit 30, and the reference reception signal processing unit 66 and the selective reception signal processing unit 64 perform processing. A received information storage unit 68 (SA5) for storing the received reference received signal and the selected received signal, and the received information storage unit 68. A signal synchronization unit 70 (SA8) that synchronizes the plurality of reference reception signals that have been synchronized with each other, and is stored in the reception information storage unit 68 according to the correction amount of each reference reception signal that is synchronized by the signal synchronization unit 70 Between the reception tag correction unit 72 (SB3, SB3 ′) for correcting the corresponding selection reception signal and the wireless tag 14 using a plurality of selection reception signals corrected by the reception signal correction unit 72. Since the directivity control unit 74 (SB6) for controlling the communication directivity of the signal is provided, the reception operation is performed while switching the reception antenna element 28 that receives the signal, thereby reducing the number of reception circuits 20 to be provided. In addition to being able to reduce the number of reception antenna elements 28, the reference reception signals received by the reference antenna elements 40 are used to individually receive the reception timings. It can be suitably synchronized with respect to the received signal received by grayed. That is, it is possible to provide a radio reception apparatus that can suitably perform directivity control with the simplest possible configuration.

  In addition, the signal synchronization unit 70 determines the correction amount of each reference reception signal so that the correlation of the reference reception signals at each reception timing is maximized. The reference received signal can be synchronized.

  Further, since the signal synchronization unit 70 determines the correction amount of each reference reception signal so that the start positions of the communication signals of the reference reception signal at the respective reception timings coincide with each other, it is simple in a practical manner. The plurality of reference received signals can be synchronized with each other.

  The received signal correction unit 72 corrects the delay amount of the corresponding selected received signal based on the delay when synchronizing the plurality of reference received signals. The selected received signals can be synchronized.

  Further, the received signal correction unit 72 corrects the amplitude of the corresponding selected received signal based on the amplitude when the plurality of reference received signals are synchronized, so that the communication signal strength from the communication target is increased. Even if a difference occurs at each reception timing, the amplitude ratios of the plurality of selected reception signals can be adjusted in a practical manner.

  In addition, since the directivity control unit 74 controls communication directivity with the communication target by phased array processing, the reception directivity from the communication target can be controlled in a practical manner.

  Moreover, since the directivity control unit 76 performs communication directivity control with the communication target by adaptive array processing, the reception signal from the communication target can be received efficiently.

  The communication target transmits the same signal a plurality of times, and the antenna switching unit 30 switches so that the signal transmitted from the communication target is received by a single receiving antenna element 28, respectively. Therefore, it is possible to obtain a reception result equivalent to the case where the signals transmitted from the communication target are simultaneously received by the plurality of receiving antenna elements 28.

  The reception information storage unit 68 stores phase information of the reference reception signal and the selection reception signal processed by the reference reception signal processing unit 66 and the selection reception signal processing unit 64. In addition to being able to execute reception processing such as direction detection of the communication target based on the above, the amount of information to be stored can be reduced compared to storing the reference reception signal and the selective reception signal itself.

  Since the three receiving antenna elements 28 are provided, the reception directivity from the communication target can be controlled by a necessary and sufficient number of receiving antenna elements 28.

  In addition, since the single reception circuit 20 for processing the reception signal received by the reception antenna element 28 is provided, the number of reception circuits 20 to be provided in the wireless reception device may be minimized. it can.

  The communication target is a wireless tag 14 that can send back a response signal in response to a predetermined transmission signal, and the wireless reception device includes a wireless transmission device that transmits a predetermined transmission signal to the wireless tag 14. Since the wireless tag communication device 12 reads and / or writes information from / to the wireless tag 14 by communicating information with the wireless tag 14, For the wireless tag communication device 12 that communicates information between the wireless communication devices, it is possible to apply a wireless reception device that can perform directivity control with the simplest possible configuration. Further, communication with the wireless tag 14 has a smaller communication data amount than normal communication, and even if the same communication is performed a plurality of times, the time required for the communication can be shortened, and all timing control related to communication is performed on the wireless tag communication device 12 side. This is suitable for this system.

  The wireless transmission device transmits the transmission signal so that the same reply signal is replied a plurality of times from the wireless tag 14 to be communicated, and the antenna switching unit 30 includes the wireless tag 14. In this case, the response signals returned from the wireless tag 14 are simultaneously received by a plurality of reception antenna elements 28. An equivalent reception result can be obtained.

  In addition, the wireless transmission device can selectively transmit a transmission signal based on a plurality of types of transmission commands, and the wireless reception device can transmit a transmission signal corresponding to the transmission signal transmitted toward the wireless tag 14. In response to the command, the first reception processing using the selective reception signal received by the plurality of reception antenna elements 28 and the second reception processing using the reference reception signal received by the reference antenna element 40 are switched. In the communication corresponding to the transmission command that requires a relatively high reception accuracy such as “Scroll ID” that is a command for requesting a response to the specific wireless tag 14, the plurality of reception antenna elements 28 are used. In the communication range, such as “PING” which is a command for checking the presence / absence of the wireless tag 14 in the communication range, a communication accuracy that does not require such high reception accuracy is used. By performing reception processing using the single reference antenna element 40, communication time can be shortened as much as possible while guaranteeing required reception accuracy.

  Next, another preferred embodiment of the present invention will be described in detail with reference to the drawings. In addition, regarding the following description, the same code | symbol is attached | subjected about the part which overlaps with the above-mentioned Example, and the description is abbreviate | omitted.

  FIG. 9 is a diagram for explaining the configuration of the wireless tag communication device 100 in which the wireless reception device according to the second embodiment of the present invention is incorporated. As shown in FIG. 9, in the RFID tag communication apparatus 100 of the present embodiment, the transmission signal output from the transmission signal generation unit 24 is supplied to the transmission antenna element 26 and received by the transmission antenna element 26. A transmission / reception separating unit 102 is provided for supplying the received signal as a reference received signal to the second cancel processing unit 42. That is, the transmitting antenna element 26 also functions as a reference antenna element for receiving the reference reception signal. As the transmission / reception separating unit 102, a circulator or a directional coupler is preferably used.

  Thus, according to the present embodiment, transmission / reception is common for transmitting a predetermined transmission signal to the wireless tag 14 and receiving a return signal returned from the wireless tag 14 as a reference reception signal in response to the transmission signal. Since the antenna element 26 is provided, the RFID tag communication apparatus 100 having a configuration as simple as possible can be realized.

  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 selective reception signal processing unit 64, the reference reception signal processing unit 66, the reception information storage unit 68, the signal synchronization unit 70, the reception signal correction unit 72, the directivity control unit 74, etc. Is also provided as a control function of the DSP 16, but may be provided as individual control devices. Also, it does not matter whether these controls are based on digital signal processing or analog signal processing.

  In the above-described embodiment, the first cancellation processing unit 32, the first intermediate signal generation unit 36, and the selective reception signal A / D converter are used as a reception circuit for processing the reception signal received by the reception antenna element 28. Although the receiving circuit 20 provided with 38 has been described, various modes are conceivable for such a receiving circuit. That is, the effects of the present invention can be obtained with respect to the receiving circuits provided in the same number as the receiving antenna elements 28 in the conventional technique.

  In the above-described embodiment, the wireless tag communication device 12 includes a transmission antenna element 26 that transmits the transmission signal toward the wireless tag 14 and a reply signal that is returned from the wireless tag 14 according to the transmission signal. , And a plurality of receiving antenna elements 28 for receiving the signal, respectively, are transmitted individually to the wireless tag 14, and from the wireless tag 14 according to the transmitted signal A plurality of transmission / reception antenna elements for receiving a reply signal to be returned may be provided. Even in such a configuration, the number of reception circuits to be provided can be reduced by performing the reception operation while switching the reception antenna element that receives the signal, and the effect of the present invention can be obtained.

  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 communication system with which the radio | wireless receiver which is one Example of this invention is used suitably. It is a figure explaining the structure of the radio | wireless tag communication apparatus with which the radio | wireless receiver which is one Example of this invention is integrated suitably. It is a figure explaining the structure of the radio | wireless tag which is a communication object of the radio | wireless receiver of FIG. FIG. 3 is a diagram illustrating reference reception information and a selective reception signal stored at each timing in a reception information storage unit in FIG. 2. It is a figure explaining a mode that multiple types of selection reception information read from the reception information storage part of FIG. 2 is correct | amended for head position alignment. 4 is a flowchart for explaining information communication control between the wireless tag communication apparatus of FIG. 2 and the wireless tag of FIG. 3 by a DSP. 7 is a flowchart for describing control for combining received information received by a plurality of receiving antenna elements, which is part of information communication control with the wireless tag shown in FIG. 6. 7 is a flowchart for explaining reception process switching control performed as a higher-level process of information communication control with the wireless tag illustrated in FIG. 6. It is a figure explaining the structure of the radio | wireless tag communication apparatus with which the radio | wireless receiver which is another Example of this invention is integrated suitably.

Explanation of symbols

12, 100: RFID tag communication device 14: RFID tag (communication object)
20: reception circuit 28: reception antenna element 30: antenna switching unit 40: reference antenna element 64: selective reception signal processing unit 66: reference reception signal processing unit 68: reception information storage unit 70: signal synchronization unit 72: reception signal correction unit 74: Directivity control unit

Claims (15)

A wireless reception device that receives a signal transmitted from a predetermined communication target and performs reception processing,
A single reference antenna element and a plurality of receiving antenna elements for receiving a signal transmitted from the communication target;
An antenna switching unit that selectively switches a receiving antenna element that receives the signal among the plurality of receiving antenna elements;
A reference received signal processing unit for processing a reference received signal received by the reference antenna element;
A selective reception signal processing unit for processing a selective reception signal received by the reception antenna element selected by the antenna switching unit;
A reception information storage unit for storing the reference reception signal and the selection reception signal processed by the reference reception signal processing unit and the selection reception signal processing unit;
A signal synchronization unit that synchronizes a plurality of reference reception signals stored in the reception information storage unit;
A reception signal correction unit that corrects the corresponding selected reception signal stored in the reception information storage unit according to the correction amount of each reference reception signal when synchronized by the signal synchronization unit;
A radio reception apparatus comprising: a directivity control unit that controls communication directivity with the communication target using a plurality of selective reception signals corrected by the reception signal correction unit.   The radio reception apparatus according to claim 1, wherein the signal synchronization unit determines a correction amount of each reference reception signal so that a correlation between the reference reception signals at each reception timing is maximized.   The radio reception apparatus according to claim 1, wherein the signal synchronization unit determines a correction amount of each reference reception signal so that a start position of a communication signal of the reference reception signal at each reception timing matches.   The radio reception apparatus according to any one of claims 1 to 3, wherein the reception signal correction unit corrects a delay time of a corresponding selection reception signal based on a delay when the plurality of reference reception signals are synchronized. .   The radio reception apparatus according to any one of claims 1 to 4, wherein the reception signal correction unit corrects the amplitude of a corresponding selection reception signal based on an amplitude when the plurality of reference reception signals are synchronized.   The radio reception device according to claim 1, wherein the directivity control unit controls communication directivity with the communication target by phased array processing.   The radio reception apparatus according to claim 1, wherein the directivity control unit controls communication directivity with the communication target by adaptive array processing.   The communication target transmits the same signal a plurality of times, and the antenna switching unit switches so that a signal transmitted from the communication target is received by a single receiving antenna element. Item 8. The wireless reception device according to any one of items 1 to 7.   9. The radio reception according to claim 1, wherein the reception information storage unit stores phase information of the reference reception signal and the selection reception signal processed by the reference reception signal processing unit and the selection reception signal processing unit. apparatus.   The radio receiving apparatus according to claim 1, comprising at least three receiving antenna elements.   11. The apparatus according to claim 1, further comprising a plurality of receiving circuits for processing a reception signal received by the receiving antenna element, wherein the number of the receiving circuits is smaller than the number of the plurality of receiving antenna elements. Wireless receiver.   The radio reception apparatus according to claim 1, further comprising a single reception circuit for processing a reception signal received by the reception antenna element.   The communication target is a wireless tag that can send back a response signal in response to a predetermined transmission signal, and the wireless reception device includes a wireless transmission device that transmits a predetermined transmission signal to the wireless tag. The wireless reception device according to claim 1, wherein the wireless reception device is provided in a wireless tag communication device that reads and / or writes information from and to the wireless tag by communicating information between the wireless tags.   The wireless transmission device transmits the transmission signal so that the same return signal is returned a plurality of times from the wireless tag that is a communication target, and the antenna switching unit transmits a reply from the wireless tag. The radio receiving apparatus according to claim 13, wherein each of the signals is switched so as to be received by a single receiving antenna element.   The wireless transmission device can selectively transmit a transmission signal based on a plurality of types of transmission commands, and the wireless reception device can respond to a transmission command corresponding to the transmission signal transmitted toward the wireless tag. The first reception process using the selective reception signal received by the plurality of reception antenna elements and the second reception process using the reference reception signal received by the reference antenna element can be switched. Item 15. The wireless receiver according to item 13 or 14.

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