JP4239012B2 - Wireless communication device - Google Patents

Description

  The present invention relates to a wireless communication apparatus having a variable phase shift function.

  In general wireless communication systems, for example, a cancellation control technique for creating a cancellation wave (compensation signal) for canceling (compensating) an unnecessary wave that interferes with the reception system when transmitting a transmission wave from an antenna, and combining it with the unnecessary wave It has been known. This control adjusts the phase and amplitude of the signal demultiplexed from the transmission system with a variable phase shifter and variable attenuator, creates a cancellation wave, and combines it with the reception system with a multiplexer to eliminate unwanted waves. It cancels out (for example, refer to Patent Document 1).

  Similarly, as another example of a wireless communication system using a variable phase shifter in a transmission circuit or a reception circuit, in order to perform wireless communication with high sensitivity through a plurality of antenna elements, directivity by a plurality of antenna elements is limited to one direction. There are also known so-called phased array control that keeps it strong and changes its direction sequentially, so-called adaptive array control that changes the directivity by a plurality of antenna elements so that the receiving sensitivity to the RFID circuit element is optimized. Yes.

  In addition, there is also known a wireless communication system that uses a variable phase shifter to stabilize the reception level even when the relative positional relationship with the receiver fluctuates drastically (see, for example, Patent Document 2).

JP-A-8-122429 (paragraph numbers 0030 to 0046, FIGS. 1 and 4) Japanese Patent Laid-Open No. 5-206919 (paragraph numbers 0010 to 0029, FIG. 1)

  However, in the above prior art, how to configure the variable phase shifter, and how to make the entire circuit as simple as possible and reduce costs when the number of antenna elements increases. There was no particular consideration for this.

  An object of the present invention is to provide a wireless communication apparatus that can realize a variable phase shifter with a relatively simple structure and can construct an entire circuit at low cost even when the number of antenna elements increases.

In order to achieve the above object, the first invention provides a transmission means capable of transmitting a carrier wave for accessing a communication target to the communication target, and a transmission from the communication target in accordance with a transmission signal from the transmission means. A receiving means capable of receiving a signal, a signal generating circuit for generating a canceling wave for canceling an unnecessary wave that may be generated based on a transmission signal from the transmitting means when the signal is received by the receiving means, and the carrier wave Sine wave generation for generating a first sine wave signal and a second sine wave signal that are different in phase from the first sine wave signal and are combined with the first sine wave signal to generate the cancellation wave And the signal generation circuit includes: a variable attenuator or a variable gain amplifier that controls the amplitude of the first and second sine wave signals; and an inverting unit that can switch between inversion and non-inversion of the polarity. wherein the sinusoidal An amplitude control means for controlling the amplitude of each of the first and second sine wave signals generated by the generation means, and the first sine wave signal and the second sine wave signal controlled by the amplitude control means are synthesized. , characterized in that it comprises a sine wave synthesizing means for generating a synthesized sine wave signal as the canceling wave.

In the wireless communication apparatus according to the first aspect of the present invention, a carrier wave is transmitted from a transmission unit to a communication target, and a signal from the communication target corresponding thereto is received by the reception unit. When the signal is received by the receiving means, unnecessary waves (so-called wraparound) that can be generated based on the transmission signal from the transmitting means are canceled by the canceling wave generated by the signal generation circuit. Thereby, the reception sensitivity can be improved.
At this time, a sine wave generating means is provided to generate the first sine wave signal as the carrier wave. The sine wave generating means also generates a second sine wave signal combined with the first sine wave signal. Corresponding to this, the signal generation circuit controls the amplitude of each of the first sine wave signal and the second sine wave signal having different phases from each other by the amplitude control means, and then synthesizes the synthesized sine wave by the sine wave synthesis means. Generate a signal. Specifically, in the amplitude control means, the amplitude of the first and second sine wave signals is controlled by the variable attenuator or the variable gain amplifier, and the polarity is inverted / non-inverted by the inverting means, so that The amplitude and polarity of the first and second sine wave signals can be freely set, and a combined sine wave signal having a desired phase can be generated by the sine wave combining means.
For example, if the first sine wave signal and the second sine wave signal are different in phase by 90 °, and if it is desired to generate a combined sine wave signal having a phase θ and an amplitude A, the amplitude of the first sine wave signal is set to A cos θ. On the other hand, the amplitude of the second sine wave signal whose phase is shifted by 90 ° is assumed to be A sin θ, and these two signals may be combined (= vector sum is taken). In this way, a sine wave signal having any phase and amplitude can be synthesized and output as desired only by controlling the amplitudes of the first sine wave signal and the second sine wave signal. In addition, the phase difference is not limited to 90 °, and other than that, a sine wave signal having an arbitrary amplitude and phase can be similarly synthesized using two sine wave signals having different phases.
As described above, by synthesizing a desired sine wave signal by combining two sine wave signals having different amplitudes, a phase variable function equivalent to that of a normal variable phase shifter can be realized with a relatively simple structure. Can do. And by such a phase variable function, an unnecessary wave can be reliably canceled by matching a phase freely with any phase of an unnecessary wave.

  When a plurality of antenna elements are used for transmission, the sine wave generating means is common to all antenna elements, and the first and second sine wave signals generated by the common sine wave generating means are used for each antenna. Amplitude control and synthesis are sufficient with amplitude control means and sine wave synthesis means provided for each element. Therefore, even when the number of antenna elements increases, the entire circuit can be constructed relatively inexpensively.

  In a second aspect based on the first aspect, the sine wave generating means generates the first sine wave signal and the second sine wave signal that are approximately 90 degrees out of phase with each other, and the sine wave synthesizing means is The composite sine wave signal having a different amplitude and phase from the first and second sine wave signals is generated.

  When synthesizing by the sine wave synthesizing means to generate a synthesized sine wave signal, if the phase of the first sine wave signal and the second sine wave signal are different by 90 °, they become the sin signal and the cosine signal as they are, and they are combined. Thus, since a desired sine wave signal can be synthesized, the amplitude control becomes easy.

A third invention is characterized in that, in the second invention, the sine wave synthesizing means generates the synthesized sine wave signal having substantially the same amplitude as that of the unnecessary wave and having a phase reversed.

As a result, unnecessary waves (wraparound) that can be generated based on the transmission signal from the transmission means can be sufficiently canceled by the cancellation wave, and the reception sensitivity can be improved reliably .

  In a fourth aspect based on the third aspect, the sine wave generating means includes a first digital-analog converter and a second sine wave sampling line, wherein the sampling string of the sine wave is the first sine wave signal and the second sine wave signal. It is a digital-analog converter.

  A sampling sequence of sine waves can be converted by first and second digital-analog converters, respectively, to generate first and second sine wave signals.

According to a fifth aspect of the present invention, in the third aspect, combining means for combining the received signal received by the receiving means and the combined sine wave signal from the sine wave combining means to generate a corrected received signal; An analog-to-digital converter that digitally converts the corrected received signal generated by the multiplexing means, and a clock signal that is input to one digital-to-analog converter and a clock signal that is input to the analog-to-digital converter Is a common signal or a signal generated from a common oscillation means.

  A first digital-analog converter that uses a common clock signal or a clock signal generated by a common oscillating means as a clock signal, and a sine wave sampling string as a first sine wave signal, and a multiplexing means The analog-to-digital converter for digitally converting the corrected received signal generated in step S3 can be operated in synchronization.

  According to a sixth aspect of the present invention, in the fifth aspect of the invention, the up-converter means for up-converting the frequency of the combined sine wave signal output from the sine wave combining means, and the frequency of the corrected reception signal generated by the combining means Downconverter means for down-converting.

  By providing up-converter means for up-converting the frequency of the synthesized sine wave signal, the sine wave synthesis means can perform synthesis at a relatively low frequency before up-conversion, thereby reducing costs. it can. Further, by providing a down-converter means for down-converting the frequency of the corrected reception signal generated by the multiplexing means, when the corrected reception signal is subsequently A / D converted, the conversion can be performed at a relatively low frequency. And cost can be reduced.

A seventh aspect based on the fifth or sixth invention, the sinusoidal synthesis unit further generates the synthesized sine wave signal, such as phase is reversed at substantially the same amplitude and the carrier component before Symbol corrected reception signal It is characterized by doing.

As a result, the composite sine wave signal can be combined with the corrected reception signal to cancel the carrier component secondarily, so that the reception sensitivity can be improved more reliably.

  According to an eighth aspect of the present invention, the first or second aspect of the invention includes a plurality of antenna elements that perform information communication with a communication target in a non-contact manner, and the sine wave synthesizing unit includes the plurality of antenna elements as the synthesized sine wave signal A synthetic sine wave signal whose phase is controlled is generated for each antenna element for transmitting to the communication target while controlling directivity by the antenna element.

  Thereby, it can transmit to communication object, controlling the directivity by a some antenna element using the signal which generate | occur | produced in the sine wave synthetic | combination means.

  In a ninth aspect based on the eighth aspect, the sine wave combining means holds the directivity by the plurality of antenna elements as the combined sine wave signal so as to become stronger in only one direction, and sequentially changes the direction. However, a synthesized sine wave signal whose phase is controlled so as to be transmitted to the communication target is generated.

  This makes it possible to perform so-called phased array control in which the directivity by a plurality of antenna elements is maintained so that only one direction becomes stronger and the direction is sequentially changed, thereby improving communication sensitivity.

  In a tenth aspect based on the eighth aspect, the sine wave synthesizing unit sets the directivity by the plurality of antenna elements as the synthesized sine wave signal to the communication target so that reception sensitivity from the communication target is optimized. A synthetic sine wave signal having a controlled amplitude and phase for transmission is generated.

  This makes it possible to perform so-called adaptive array control that changes the directivity of the plurality of antenna elements so that the reception sensitivity from the communication target is optimal, thereby improving the communication sensitivity.

  According to an eleventh aspect of the present invention, in any one of the eighth to tenth aspects, the sine wave generating means is a digital-analog converter that uses a sine wave sampling string as a sine wave signal. .

  The first and second sine wave signals can be generated by converting the sampling sequence of the sine wave with a digital-analog converter.

  A twelfth aspect of the invention is characterized in that in any one of the eighth to tenth aspects of the invention, there is provided up-converter means for up-converting the frequency of the synthesized sine wave signal output from the sine wave synthesis means. .

  By providing up-converter means for up-converting the frequency of the synthesized sine wave signal, the sine wave synthesis means can perform synthesis at a relatively low frequency before up-conversion, thereby reducing the cost of the wireless communication device. Can be reduced.

  [0033]

  [0034]

In a thirteenth aspect based on any one of the first to twelfth aspects, the amplitude control means generates a control signal and outputs it as a serial signal, and the serial signal from the logic circuit is parallelized. A control signal for controlling the amplitude and polarity of the first and second sine wave signals by using a part of the value, and generating a control signal for the variable attenuator or variable gain amplifier and the inverting means, respectively. characterized by further comprising a register means for outputting.

  The amplitude control signal output from the logic circuit and converted into a parallel signal is output to a variable attenuator or a variable gain amplifier, whereby the amplitudes of the first and second sine wave signals can be controlled based on the control signal. The polarity of the first and second sine wave signals can be controlled based on the control signal by outputting the polarity control signal to the inverting means.

  According to the present invention, it is possible to provide a wireless communication apparatus that can realize a variable phase shifter with a relatively simple structure and can construct an entire circuit at low cost even when the number of antenna elements increases.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a system configuration diagram showing an overall outline of an RFID tag communication system to which this embodiment is applied.

  In FIG. 1, the RFID tag communication system S includes an interrogator 1 (only one is shown, but there may be a plurality of interrogators) as a wireless communication device of the present embodiment, and a responder corresponding thereto. This is a so-called RFID (Radio Frequency Identification) communication system composed of a wireless tag T.

  The wireless tag T includes a wireless tag circuit element To including an antenna 151 and an IC circuit unit 150.

  In this example, the interrogator 1 transmits and receives signals by wireless communication with the antenna 151 of the RFID circuit element To, and in this example, the antenna 2 and the RFID circuit via the antenna 2. In order to execute at least one of reading and writing of information with respect to the element To, a transmission signal (query wave Fc) is output as a digital signal, or a return signal (reflection wave Fr) from the RFID circuit element To is demodulated. A digital signal processor (DSP) 100 that executes digital signal processing such as the above, and a transmission signal output from the DSP 100 is converted into an analog signal and transmitted as the interrogation wave Fc via the antenna 2 or the RFID circuit element The reflected wave Fr from To is received, converted into a digital signal, and supplied to the DSP 100. The transmission / reception circuit 200 executes processing such as the above.

  When an interrogation wave Fc, which is a transmission signal, is transmitted from the interrogator 1, the interrogation wave Fc is modulated based on a predetermined information signal in the RFID tag circuit element To of the RFID tag T that has received the inquiry wave Fc. Information is transmitted and received by the interrogator 1 receiving and demodulating the reflected wave Fr.

  FIG. 2 is a block diagram showing an example of a functional configuration of the RFID circuit element To provided in the RFID tag T.

  In FIG. 2, the RFID circuit element To receives the interrogation wave Fc and transmits the reflection wave Fr in a non-contact manner using the antenna 2 on the interrogator 1 side and a high frequency such as a UHF band. And the IC circuit unit 150 that is connected to the antenna 151 and performs digital signal processing.

  The IC circuit unit 150 includes a rectifying unit 152 that rectifies the carrier wave received by the antenna 151, a power source unit 153 that accumulates energy of the carrier wave rectified by the rectifying unit 152 and serves as a driving power source, and the antenna 151. A clock extraction unit 154 that extracts a clock signal from the received carrier wave and supplies the clock signal to the control unit 157; a memory unit 155 that functions as an information storage unit that can store a predetermined information signal; and a modem that is connected to the antenna 151 And a controller 157 for controlling the operation of the RFID circuit element To via the rectifier 152, the clock extractor 154, the modulator / demodulator 156 and the like based on the power supply from the power supply unit 153. ing.

  The modem 156 demodulates the communication signal received from the antenna 2 of the interrogator 1 received by the antenna 151 and reflects and modulates the carrier wave received from the antenna 2 based on the return signal from the controller 157. .

  The control unit 157 interprets the received signal demodulated by the modulation / demodulation unit 156, generates a return signal based on the information signal stored in the memory unit 155, and performs basic control such as returning by the modulation / demodulation unit 156. Execute proper control.

  The above description has been made by taking the RFID tag circuit element To of the type that does not use a subcarrier as an example. However, the present invention is not limited to this, and includes a subcarrier oscillation unit and a subcarrier modulation unit (both not shown). The subcarrier generated by the oscillating unit may be modulated by the subcarrier modulating unit based on a predetermined information signal input via the control unit 157 and returned from the antenna 151.

  FIG. 3 is a functional block diagram showing a functional configuration of the interrogator 1.

  In FIG. 3, the interrogator 1 includes the DSP 100, the transmission / reception circuit 200, and the antenna 2 as described above.

  The DSP 100 is a so-called microcomputer system that includes a CPU, a ROM, a RAM, and the like, and performs signal processing according to a program stored in advance in the ROM while using a temporary storage function of the RAM.

  The DSP 100 forms a function table 40 in which sampling values corresponding to each phase are stored in advance at a predetermined sampling point, and a transmission signal (carrier wave) to the RFID circuit element To based on the sampling values in the function table 40. Therefore, the transmission digital signal output unit 20 that outputs a digital signal (a signal obtained by sampling a sine wave) and the transmission digital signal output unit 20 based on the sampling value of the function table 40, for example, are only one sample. By outputting a delayed digital signal (a signal obtained by sampling a sine wave), the transmission digital signal output from the transmission digital signal output unit 20 is shifted by 90 ° to output a transmission digital signal that is 90 ° out of phase. The phase (phase conversion) unit 41 and the carrier wave are changed based on a predetermined command signal. A modulation unit 22 that outputs a modulation signal for adjusting access information, and a first cancel signal (primarily canceling an unnecessary wave based on a transmission signal from the antenna 2 to the RFID circuit element To) The first cancellation control signal output unit 24 outputs a signal for controlling the generation of the first cancellation signal), and is output from the first cancellation control signal output unit 24 according to the amplitude and phase that the first cancellation signal should have. A first cancel signal control unit 26 that controls the control signal, and a second cancel control signal that outputs a signal for controlling generation of a second cancel signal (second cancel signal) for secondarily canceling the unnecessary wave The output unit 28 and a second cancel that controls the control signal output from the second cancel control signal output unit 28 according to the amplitude and phase that the second cancel signal should have A signal control unit 30; a demodulation unit 32 for demodulating a reception signal received by the antenna 2; a direct current component detection unit 34 for detecting a direct current component (DC component) of the demodulated signal output from the demodulation unit 32; A received signal amplitude detector 36 for detecting the amplitude of the received signal, and a first synthesized signal amplitude detector 38 for detecting the amplitude of the first synthesized signal output from a first signal synthesizer 58 described later. Yes.

  The transmission / reception circuit 200 includes a high-speed first transmission signal D / A converter 42 that converts the transmission digital signal output from the transmission digital signal output unit 20 into an analog signal and generates a first sine wave signal, and a 90 ° phase shift. A high-speed second transmission signal D / A converter 43 that converts the transmission digital signal output from the unit 41 into an analog signal and generates a second sine wave signal that is 90 ° out of phase with the first sine wave signal; The local oscillation signal output unit 44 for outputting the local oscillation signal of the signal and the frequency of the transmission signal converted into the analog signal by the D / A converter 42 are the frequency of the local oscillation signal output from the local oscillation signal output unit 44 The first up-converter 46 is set to be higher, the first amplifying unit 48 that amplifies the transmission signal output from the first up-converter 46 and changes the amplitude thereof, and the first amplifying unit 48 An output transmission signal is supplied to the antenna 2 via the transmission / reception separator 50, and a reply signal (a reception signal including a sneak signal from the transmission side) received by the antenna 2 from the RFID circuit element To. A transmission / reception separator 50 supplied to a first signal synthesis unit 58 (described later) and a second down converter 74, and a low-speed converter that converts the first cancel control signal output from the first cancel control signal output unit 24 into an amplitude signal. The first cancellation control signal D / A converters 53 and 54 and the first and second sine wave signals from the first and second transmission signal D / A converters 42 and 43 are input, and the first cancellation control signal is input. Based on the amplitude signal from the D / A converters 53 and 54 and the polarity signal from the first cancel control signal output unit 24, the amplitude of each of the first and second sine wave signals is controlled. The first synthesized sine wave is generated by synthesizing them to generate a synthesized sine wave signal (first cancel signal) for wireless communication (in this case for primary cancellation) having a different amplitude and phase from the first and second sine wave signals. Wave signal generation circuit 80 and a second increase in which the frequency of the first cancellation signal output from first synthesized sine wave signal generation circuit 80 is increased by the frequency of the local oscillation signal output from local oscillation signal output unit 44. A converter 56 and a first signal combiner 58 that combines the first cancel signal output from the second up-converter 56 and the received signal supplied from the antenna 2 via the transmission / reception separator 50; The second amplifying unit 60 that amplifies the first synthesized signal output from the first signal synthesizing unit 58 and changes the amplitude thereof, and the first synthesized signal output from the second amplifying unit 60. The first down converter 62 that lowers the frequency of the signal by the frequency of the local oscillation signal output from the local oscillation signal output unit 44 and the amplitude of the second cancel control signal output from the second cancellation control signal output unit 28 Low-speed second cancel control signal D / A converters 63 and 64 for converting signals, and first and second sine wave signals from the first and second transmission signal D / A converters 42 and 43 are input. Based on the amplitude signal from the second cancellation control signal D / A converters 63 and 64 and the polarity signal from the second cancellation control signal output unit 28, the amplitude of each of the first and second sine wave signals is controlled. A second sine wave signal (second cancel signal) for synthesizing wireless communication (in this case for secondary cancellation) having a different amplitude and phase from the first and second sine wave signals by combining them. The synthesized sine wave signal generation circuit 90, the second cancellation signal outputted from the second synthesized sine wave signal generation circuit 90, and the first synthesized signal outputted from the first down converter 62 are synthesized (amplified as necessary). The second amplifying unit 66, the third amplifying unit 68 for amplifying the first synthesized signal output from the first down converter 62 and changing its amplitude, and the third amplifying unit 68. The first synthesized signal A / D converter 70 that digitally converts the first synthesized signal and supplies the first synthesized signal to the first synthesized signal amplitude detector 38, and the second synthesized signal output from the second signal synthesizer 66. The second synthesized signal A / D converter 72 that performs digital conversion and supplies it to the demodulator 32 and the frequency of the received signal supplied via the transmission / reception separator 50 are output from the local oscillation signal output unit 44. Local departure A second down converter 74 that lowers only the frequency of the signal, a received signal A / D converter 76 that digitally converts the received signal output from the second down converter 74 and supplies the received signal to the received signal amplitude detector 36; And a clock signal output unit 78 for outputting a predetermined clock signal.

  The clock signal output unit (oscillating means) 78 supplies a clock signal to the transmission signal D / A converters 42 and 43, and the first combined signal A / D converter 70 and the second combined signal A / D converter. The clock signal common to the transmission signal D / A converters 42 and 43 is supplied to the converter 72 and the reception signal A / D converter 76.

  The reception signal A / D converter 76 is preferably a converter having a smaller number of bits than the converter used in the first combined signal A / D converter 70 and the like. According to such a converter, there is an advantage that components relating to modulation by the RFID circuit element To can be ignored. As the local oscillation signal output unit 44, an oscillator that oscillates in the vicinity of 900 MHz or 2.4 GHz is preferably used. As the transmission / reception separator 50, a circulator or a directional coupler is generally used.

  The basic operation of the RFID tag communication system S having the above configuration will be described below with reference to (a) to (d).

(A) Signal transmission to radio tag In the radio tag communication system S having the above configuration, a transmission signal which is a digital signal is output by the transmission digital signal output unit 20 based on the function table 40 of the DSP 100 of the interrogator 1, and this transmission is performed. The digital signal is converted into an analog signal (sine wave signal) by the transmission signal D / A converter 42.

  The frequency of the transmission signal converted into an analog signal by the transmission signal D / A converter 42 is increased by the frequency of the local oscillation signal output from the local oscillation signal output unit 44 by the first up-converter 46, and further, The amplitude is increased in the first amplifying unit 48 and is modulated by the modulation signal from the modulating unit 22. The transmission signal modulated and output by the first amplifying unit 48 is supplied to the antenna 2 via the transmission / reception separator 50, and is transmitted from the antenna 2 to the RFID circuit element To as the interrogation wave Fc.

(B) Signal Reception from Radio Tag When the interrogation wave Fc from the antenna 22 is received by the antenna 151 of the radio tag circuit element To, the interrogation wave Fc is supplied to the modem unit 156 and demodulated. Further, a part of the interrogation wave Fc is rectified by the rectification unit 152 and is used as an energy source (power source) by the power supply unit 153. With this power supply, the control unit 157 generates a reply signal based on the information signal of the memory unit 155, and the modulation / demodulation unit 156 modulates the interrogation wave Fc based on the reply signal and directs the reflected wave Fr from the antenna 151 to the interrogator 100. Will be replied.

  When the reflected wave Fr from the RFID circuit element To is received by the antenna 2 of the interrogator 1, the reflected wave Fr is received as a received signal via the transmission / reception separator 50, and the first signal synthesis unit 58 and the second down converter 74. To be supplied. At this time, the transmission signal that has circulated to the reception side via the transmission / reception separator 50 is also supplied to the first signal synthesis unit 58 and the second down converter 74 simultaneously with the reception signal.

  The reception signal supplied to the second down converter 74 is reduced in frequency by the frequency of the local oscillation signal output from the local oscillation signal output unit 44 and is digitally converted by the reception signal A / D converter 76. The received signal amplitude is supplied to the received signal amplitude detector 36, and the detected amplitude of the received signal is supplied to the first cancel signal controller 26.

(C) Primary cancellation The first cancellation signal control unit 26 sets the amplitude of the reception signal input from the reception signal amplitude detection unit 36 and the amplitude of the reception signal after primary cancellation input from the first combined signal amplitude detection unit 38. Based on this, the phase and amplitude of the first cancel signal for performing the primary cancellation are determined (details will be described later). The determined phase and amplitude are input to the first cancel control signal output unit 24. The first cancel control signal output unit 24 outputs a first cancel control signal which is a digital signal for generating the first cancel signal having the determined phase and amplitude.

  On the other hand, a transmission signal which is a digital signal is output from the 90 ° phase shift unit 41 based on the sampling value from the function table input to the transmission digital signal output unit 20, and this transmission digital signal is transmitted to the transmission signal D / A converter. 43 is converted into an analog signal (sine wave signal). The second sine wave signal of the transmission signal D / A converter 43 and the first sine wave signal of the transmission signal D / A converter 42 are the first combined sine wave signal generation circuit 80 and the second combined signal. Each is supplied to the sine wave signal generation circuit 90.

  In the first composite sine wave signal generation circuit 80, the first cancel control signal (polarity) from the first cancel control signal output unit 24 (or further via the first cancel control signal D / A converters 53 and 54). Based on switching polarity signals Vswc1 and Vsws1 and amplitude signals Vatc1 and Vats1) which are control voltages for amplitude control, the amplitudes of the first and second sine wave signals are synthesized and combined for primary cancellation. The combined sine wave signal (first cancel signal) is generated (details will be described later).

  The frequency of the first cancel signal output from the first synthesized sine wave signal generation circuit 80 is increased by the frequency of the local oscillation signal output from the local oscillation signal output unit 44 by the second up-converter 56. The first cancellation signal output from the second up-converter 56 and the reception signal supplied via the transmission / reception separator 50 are combined by the first signal combining unit 58, and the sneak signal from the transmission side included in the reception signal Is removed (or reduced).

  The amplitude of the first synthesized signal output from the first signal synthesizing unit 58 is changed by the second amplifying unit 60 with a predetermined gain. At this time, as described above, when the amplitude and phase of the first cancel signal are suitably determined, the signal intensity is relatively lowered and the input signal to the first down converter 62 is reduced. The gain of the unit 60 is increased as appropriate.

  The frequency of the first combined signal output from the second amplifying unit 60 is reduced by the first down converter 62 by the frequency of the local oscillation signal output from the local oscillation signal output unit 44, and the second signal combining unit 66 and the second 3 is supplied to the amplifying unit 68. Note that the gain of the third amplifying unit 68 is set to a predetermined initial value. The frequency of the clock signal output from the clock signal output unit 78 is preferably four times or an integer multiple of the frequency of the down-converted first synthesized signal (intermediate frequency signal).

  The amplitude of the first synthesized signal supplied to the third amplifying unit 68 is changed by the third amplifying unit 68 with the predetermined gain. Since the first synthesized signal output from the first down converter 62 becomes smaller as the removal (reduction) of the sneak signal from the transmission side in the first signal synthesizing unit 58 proceeds, preferably, the third amplifying unit The gain at 68 is sequentially increased accordingly.

  The first synthesized signal output from the third amplifier 68 is digitally converted by the first synthesized signal A / D converter 70 and then supplied to the first synthesized signal amplitude detector 38 to detect the amplitude thereof. The amplitude thus supplied is supplied to the first cancel signal control unit 26 and the second cancel signal control unit 30. The determination of the phase and amplitude in the first cancellation signal control unit 26 is performed according to the detection result in the reception signal amplitude detection unit 36 and the detection result in the first combined signal amplitude detection unit 38. 58 and the amplitude of the first cancel signal output from the first combined sine wave signal generation circuit 80 and up-converted are determined to be equal (and the phase is reversed). The That is, the amplitude of the first cancel signal can be determined from the detection result of the reception signal amplitude detection unit 36. Further, the phase of the first cancel signal can be determined so that the output of the amplitude is minimized from the detection result of the first combined signal amplitude detector 38.

(D) Secondary Cancel On the other hand, the second cancellation signal control unit 30 that has input the amplitude detection value in the first combined signal amplitude detection unit 38 receives the detection value (the amplitude of the received signal after the primary cancellation) and the second combination. Based on the second synthesized signal from the signal A / D converter 72, the phase and amplitude of the second cancellation signal for performing the secondary cancellation are determined (details will be described later). The determined phase and amplitude are input to the second cancel control signal output unit 28. The second cancel control signal output unit 28 outputs a second cancel control signal that is a digital signal for generating the second cancel signal having the determined phase and amplitude.

  Here, in the second synthesized sine wave signal generation circuit 90, similarly to the first synthesized sine wave signal generation circuit 80, the second cancellation control signal output unit 28 (or further the second cancellation control signal D / A conversion). Based on the second cancel control signal (via polarity devices Vswc2 and Vsws2 which are control signals for polarity switching and amplitude signals Vatc2 and Vats2 which are control voltages for amplitude control; see also below) A composite sine wave signal (second cancel signal) for secondary cancellation is generated by combining the first and second sine wave signals while controlling the amplitudes (details will be described later).

  The second cancellation signal output from the second combined sine wave signal generation circuit 90 is combined with the down-converted first combined signal supplied from the first down converter 62 and the second signal combining unit 66. Thus, the sneak signal from the transmission side included in the first combined signal is removed (reduced).

  The second synthesized signal output from the second signal synthesizer 66 is digitally converted by the second synthesized signal A / D converter 72 and then supplied to the demodulator 32. The demodulator 32 demodulates the second synthesized signal. Then, the information signal of the RFID circuit element To is read out. The second synthesized signal demodulated by the demodulator 32 is input to the DC component detector 34 to detect the DC component of the demodulated signal, and the detection result is supplied to the second cancel signal controller 30. The determination of the phase and amplitude in the second cancellation signal control unit 30 is performed by determining the amplitude of the DC component detected by the DC component detection unit 34 corresponding to the sneak signal from the transmission side and the first combined signal amplitude detection unit 38. On the basis of the detection result at, the amplitude of the down-converted first synthesized signal input to the second signal synthesizer 66 is equal to the amplitude of the second cancellation signal from the second synthesized sine wave signal generation circuit 90. (And the phase is reversed). In other words, the amplitude of the second cancellation signal can be determined based on the detection result of the first composite signal amplitude detection unit 38, and the second cancellation signal can be minimized so that the amplitude of the DC component detected by the DC component detection unit 34 is minimized. The phase can be determined.

  Through the basic communication operations described in the above (a) to (d), the RFID tag communication system S according to the present embodiment suitably removes (reduces) the sneak signal from the transmission side included in the reception signal from the antenna 2. High-sensitivity communication can be realized.

  In the RFID tag communication system S having the basic configuration and operation as described above, the main part of the present embodiment is the first and second synthesized sine wave signal generation circuits 80 and 90, which are cos signals having different amplitudes (first sine wave). Signal) and a sin signal (second sine wave signal) whose phase is shifted by 90 ° and combining the desired sine wave signal to realize a phase variable function with a relatively simple structure. .

  FIG. 4 is an explanatory diagram by vector display for explaining the principle of the present invention. In FIG. 4A, for example, when it is desired to generate a composite sine wave signal having a phase θ and an amplitude A, the amplitude of the first sine wave signal (in other words, cosine wave signal) is set to Acos θ, while the phase is The amplitude of the second sine wave signal shifted by 90 ° is set to Asin θ, and these two signals may be combined (= vector sum is taken). In this way, it is only necessary to control the amplitudes of the first sine wave signal and the second sine wave signal, and as shown in FIGS. Signals can also be combined and output as desired. In FIGS. 4B to 4D, two signals having a phase difference of 90 ° that can be used by the common function table are used as described later. However, the phase difference is not limited to 90 °. Instead, as shown in FIG. 4E, if two signals A1 and A2 having different phases are used, a sine wave signal having an arbitrary amplitude and phase can be similarly synthesized.

  The function table 40 of the DSP 100 shown in FIG. 3 is a sine wave table in which sampling values corresponding to respective phases are stored in advance at predetermined sampling points as described above. In the present embodiment, based on the function table 40, the transmission digital signal output unit 20 and the 90 ° phase shift unit 41 generate the first sine wave signal and the second sine wave signal. 5A to 5D show examples of the sine wave table (IF table) stored in the function table 40. FIG.

  FIGS. 5A to 5D are examples in which the control is simplified by setting the oscillation frequency to 1/4 of the sampling frequency.

  In the example of FIG. 5A, the value of “cosφ” is stored in advance for the initial phase “φ”, and “φ = 0, (1/2) π, 1, (3/2) π, .. ”Is read out, and the transmission digital signal output unit 20 directly uses these continuous values as the first transmission signal D / A. By outputting to the converter 42, the first transmission signal D / A converter 42 to which the signal is input generates the first sine wave signal (= cosine wave signal). In this case, the 90 ° phase shifter 41 receives the output from the transmission digital signal output unit 20 and delays it by one sample, or outputs “φ = 0, (1/2) π, 1, (3/2 ) π,... ”is shifted by one, and“ 0,1,0, -1,... ”is read and output to the second transmission signal D / A converter 43, thereby inputting the second transmission signal D. The / A converter 43 generates a second sine wave signal that is 90 ° out of phase with the first sine wave signal.

  In the example of FIG. 5B, the values of “cosφ” for the first sine wave signal and “sinφ” for the second sine wave signal are individually stored. Then, "1,0, -1,0, ...", "0,1,0, -1" for "φ = 0, (1/2) π, 1, (3/2) π, ..." ,... Are read out, and the transmission digital signal output unit 20 outputs a continuous value of “1,0, −1,0,...” To generate a first transmission signal D / A converter. 42 generates the first sine wave signal, while the 90 ° phase shifter 41 outputs a continuous value of “0,1,0, -1,...” And the second transmission signal D / A converter 43 The second sine wave signal is generated.

  Instead of the examples of FIGS. 5A and 5B, the initial phase φ is set to another arbitrary value as shown in FIGS. 5C and 5D (in this example, φ = (1/4) π, (3/4) π, (5/4) π, (7/4) π,… ”, and the corresponding discrete continuous values (in this example,“ 0.7071, -0.7071,- 0.7071,0.7071, ... "or" 0.7071,0.7071, -0.7071, -0.7071, ... ") may be read out.

  As described above, the first transmission signal D / A converter 42 and the second transmission signal D / A converter 43 have a phase of 90 based on the discrete values read out as illustrated in FIGS. 5A to 5D. A first sine wave signal and a second sine wave signal that are deviated from each other are generated and input to the first and second combined sine wave signal generation circuits 80 and 90.

  As described above, when a sine wave is generated using the sine wave table of the function table 40, the reading position in the table may be changed to change the amplitude in order to change the phase of the sine wave signal. For this purpose, the read sine wave signal may be multiplied by a predetermined control value.

FIG. 6 is a circuit diagram illustrating a detailed configuration of the first synthesized sine wave signal generation circuit 80.
In FIG. 6, the first synthesized sine wave signal generation circuit 80 operates in accordance with the control voltage (amplitude signal: the same applies hereinafter) Vatc1 from the first cancel control signal D / A converter 53, and the first A variable attenuator 85 as amplitude control means for controlling the amplitude of the first sine wave signal (cosωt) from one transmission signal D / A converter 42, and a gain for inverting the polarity of the first sine wave signal Is operated in accordance with the amplifier 81 with −1 and the polarity switching control signal (polarity signal: hereinafter the same) Vswc1 from the first cancel control signal output unit 24, and the first sine wave signal is inverted or not. The switch 83 for switching inversion and the second sine from the second transmission signal D / A converter 43 operate according to the control voltage Vats1 for amplitude control from the first cancel control signal D / A converter 54. Controls the amplitude of the wave signal (sinωt) A variable attenuator 86 as an amplitude control means, an amplifier 82 with a gain of -1 to invert the polarity of the second sine wave signal, and the polarity switching control from the first cancel control signal output unit 24 As a sine wave synthesizing unit that operates in response to the signal Vsws1 and synthesizes the outputs from the variable attenuators 85 and 86 and the switch 84 for switching the inversion / non-inversion of the second sine wave signal to generate a synthesized sine wave signal. And an adder 87.

  With the above configuration, the first cancel control is performed by controlling the amplitudes of the first and second sine wave signals by the variable attenuators 85 and 86 in accordance with the control voltages Vatc1 and Vats1 from the D / A converters 53 and 54. In accordance with the control signals Vswc1 and Vsws1 from the signal output unit 24, the amplifiers 81 and 82 as the inverting means and the switches 83 and 84 switch the inversion and non-inversion of the polarity of the first and second sine wave signals. The amplitude and plus / minus of the previous first and second sine wave signals (sinωt and cosωt) can be freely set, and a synthesized sine wave signal having a desired phase is generated by the adder 87 and sent to the second up-converter 56. It is designed to output.

  Note that the second synthesized sine wave signal generation circuit 90 has the same configuration as described above, and a detailed illustration thereof is omitted. However, the variable attenuator 85 according to the control voltages Vatc2 and Vats2 from the D / A converters 63 and 64 is omitted. , 86 control the amplitude of the first and second sine wave signals, and in accordance with the control signals Vswc2, Vsws2 from the second cancel control signal output unit 28, the amplifiers 81, 82 as the inverting means and the switches 83, 84 By switching between inversion and non-inversion of the polarity of the first and second sine wave signals, the amplitude and plus / minus of the first and second sine wave signals (sinωt and cosωt) before synthesis can be freely set, and the desired phase The combined sine wave signal is generated by the adder 87 and output to the second signal combining unit 66.

  The configuration of the combined sine wave signal generation circuit is not limited to the above, and other configurations may be used.

  FIG. 7 is a circuit diagram illustrating a modification of the combined sine wave signal generation circuit. In FIG. 7, this combined sine wave signal generation circuit 80 'replaces the variable attenuators 85 and 86 of the combined sine wave signal generation circuit 80 shown in FIG. This is a case where 86 'is used. Similar to the variable attenuator 85, the variable amplifier 85 ′ operates in accordance with the amplitude control voltage Vatc1 from the first cancel control signal D / A converter 53, and the first transmission signal D / A converter. The amplitude of the first sine wave signal (cosωt) from 42 is controlled. Similar to the variable attenuator 86, the variable amplifier 86 'operates in accordance with the amplitude control voltage Vatc1 from the first cancel control signal D / A converter 54, and the second transmission signal D / A converter. The amplitude of the first sine wave signal (cosωt) from 43 is controlled. Other configurations and operations are the same as those of the synthetic sine wave signal generation circuit 80. The synthesized sine wave signal generation circuit 90 can have the same configuration.

  FIG. 8 is a circuit diagram showing another modification of the combined sine wave signal generation circuit. The functions equivalent to those in FIG. 6 or FIG. 7 are denoted by the same reference numerals, and description thereof will be simplified or omitted as appropriate.

8, in this example, absolute value circuits AVC1 and AVC2 are provided for both the configuration related to the first sine wave signal and the configuration related to the second sine wave signal. Each of the absolute value circuits AVC1 and AVC2 has a known configuration in which two comparators C, two diodes D, and five resistors R are combined in this example.

  The absolute value circuit AVC1 inputs a control voltage (which also has polarity) Vatc ′ corresponding to the control voltage Vatc (generic name of Vatc1 and Vatc2), and inputs the absolute value | Vatc ′ | to the variable attenuator 85. Output. Further, Vatc ′ itself is supplied to the other side of the comparator 88 grounded on one side, and only the polarity (plus or minus) is taken out and supplied to the switch 83. In the switch 83, the polarity switching using the amplifier 81 as described above is performed. I do.

  The absolute value circuit AVC2 inputs a control voltage (but also having polarity) Vats ′ corresponding to the control voltage Vats (generic name of Vats1, Vats2), and inputs the absolute value | Vats ′ | to the variable attenuator 86. Output. Further, Vats ′ itself is supplied to the other side of the comparator 89 grounded on one side, and only the polarity (plus or minus) is taken out and supplied to the switch 84. In the switch 84, the polarity switching using the amplifier 82 as described above is performed. I do.

  In this modification, the control signals Vswc1 and Vsws1 from the first cancel control signal output unit 24 described above are not necessary, and the control voltages Vatc1 ′ and Vats1 ′ having both polarities as described above from the D / A converters 53 and 54. In response to the absolute values | Vatc1 ′ | and | Vats1 ′ | of the control voltages Vatc1 ′ and Vats1 ′ output via the absolute value circuits AVC1 and AVC2, the first and second variable attenuators 85 and 86 Controls the amplitude of the sine wave signal. Then, the amplifiers 81 and 82 and the switches 83 and 84 as inverting means switch the inversion and non-inversion of the polarities of the first and second sine wave signals in accordance with the polarity control signals from the comparators 88 and 89. The amplitude and plus / minus of the first and second sine wave signals (sinωt and cosωt) before synthesis are freely set. As a result, a synthesized sine wave signal having a desired phase is generated by the adder 87 and output to the second up-converter 56.

  The second synthesized sine wave signal generation circuit 90 can also have the same configuration as described above. The control signals Vswc2 and Vsws2 from the second cancel control signal output unit 28 are not necessary, and the control voltages Vatc2 ′ and Vats2 ′ having the same polarity as the above are output from the D / A converters 63 and 64, and the absolute value circuit The amplitudes of the first and second sine wave signals are controlled by the variable attenuators 85 and 86 according to the absolute values | Vatc2 ′ | and | Vats2 ′ | of the control voltages Vatc2 ′ and Vats2 ′ output via the AVC1 and AVC2. To do. Then, the amplifiers 81 and 82 and the switches 83 and 84 switch the polarity inversion / non-inversion according to the polarity control signals from the comparators 88 and 89, and freely set the amplitude and plus / minus of the first and second sine wave signals. Thus, a combined sine wave signal having a desired phase is generated and output to the second signal combining unit 66.

  According to this modification, as described above, the control signals Vswc1, Vsws1 from the first cancel control signal output unit 24 (or the control signals Vswc2, Vsws2 from the second cancel control signal output unit 28) are not required. Since the number of control signal lines can be reduced, the circuit configuration can be further simplified.

  In the above, the 1st transmission signal D / A converter 42 and the 2nd transmission signal D / A converter 43 constitute a sine wave generation means of each claim, and are to be communicated as a 1st sine wave signal. A carrier wave output means for generating a carrier wave for access is also configured. The antenna 2 constitutes a transmission means capable of transmitting the carrier wave output from the carrier wave output means to the communication target, and a reception means capable of receiving a transmission signal from the communication target in accordance with a transmission signal from the transmission means. Is also configured. In addition, the first signal combining unit 58 constitutes a combining unit that generates a corrected reception signal by combining the reception signal received by the receiving unit and the cancellation wave from the sine wave combining unit, and the second combined signal A / The D converter 72 constitutes an analog-to-digital converter that digitally converts the corrected reception signal generated by the multiplexing means.

  Further, the first transmission signal D / A converter 42 constitutes a first digital-analog converter having a sine wave sampling string as the first sine wave signal, and the second transmission signal D / A converter 43 is A second digital-analog converter having a sine wave sampling string as a second sine wave signal is configured. The second up-converter 56 constitutes up-converter means for up-converting the frequency of the synthesized sine wave signal output from the sine wave synthesizing means, and the corrected reception signal generated by the first down converter 62 by the multiplexing means. Down-converter means for down-converting the first frequency.

  In the RFID tag communication apparatus S according to the present embodiment configured as described above, the first transmission signal D / A converter 42 and the second transmission signal D / A converter 43 generate phases different from each other by 90 °. The synthesized sine wave signal is generated by combining the first sine wave signal and the second sine wave signal after amplitude control in the synthesized sine wave signal generation circuits 80 and 90, respectively. Thus, by combining a desired sine wave signal with a combination of a sin signal and a cos signal having different amplitudes, a phase variable function can be realized with a relatively simple structure. Further, since a sine wave signal having an arbitrary phase can be synthesized, the phase variable range is not limited as in a normal phase shifter.

  At this time, the clock signal input to the first transmission signal D / A converter 42 and the clock signal input to the second combined signal A / D converter 72 are a clock signal output unit which is a common oscillation means. 78 (or the signal itself may be common), the first transmission signal D / A converter 42 having a sine wave sampling sequence as the first sine wave signal, the primary cancellation, The second combined signal A / D converter 72 that digitally converts the corrected received signal subjected to the secondary cancellation can be operated in synchronization. As a result, a frequency shift between transmission and reception does not occur, and stable demodulation processing can be performed.

  Further, by providing the second up-converter 56 for increasing the frequency of the synthesized sine wave signal, the synthesized sine wave signal generation circuits 80 and 90 can perform synthesis at a relatively low frequency before the up-conversion. Therefore, the cost can be reduced. Further, by providing a first down converter 62 that down-converts the frequency of the corrected reception signal generated by the first signal synthesis unit 58, the corrected reception signal is then A / D converted by the second synthesis signal A / D converter 72. In some cases, the conversion can be performed at a relatively low frequency, and the cost can be reduced.

  In addition, this invention is not restricted to said form, A various deformation | transformation is possible in the range which does not deviate from the meaning and technical idea. Hereinafter, such modifications will be described.

(1) When applied to an array antenna FIG. 9 is a functional block diagram showing a functional configuration of an interrogator according to this modification, and is a diagram substantially corresponding to FIG. 3 of the above embodiment. Components equivalent to those in FIG. 3 are denoted by the same reference numerals, and description thereof is omitted or simplified as appropriate.

  In FIG. 9, in this modification, the antenna 2 is composed of one transmission / reception antenna 2 in the above embodiment, but a plurality (three in this example) of transmission / reception antennas (antenna elements) 2-1, 2. -2, 2-3. Corresponding to these, a cancel processing unit 301-1, a cancel processing unit 301-2, and a cancel processing unit 301-3 are provided in the DSP 100 ′. Since these cancel processing units 301-1 to 301-3 have the same circuit configuration, the cancel processing unit 301-1 related to the antenna 2-1 will be described as a representative as appropriate. Hereinafter, for the configurations related to the receiving antennas 2-1, 2-2, and 2-3, “−1”, “−2”, and “−3” are added to the reference numerals in the above-described embodiment, and the description will be given as appropriate. Omitted or simplified.

Similarly to the above embodiment, the function table 40, the transmission digital signal output unit 20, the 90 ° phase shift unit 41, the modulation unit 22, the first transmission signal D / A converter 42, and the second transmission signal D / A converter. 43, a local oscillation signal output unit 44, and a phased array (PAA) processing unit 302, an adaptive array (AAA) processing unit 303, etc. are provided as constituent capitals unique to this modification. Although detailed description is omitted in the adaptive array processing unit 303, the antennas 2-1, 2-2, 2 are performed by a known method based on the received signals from the antennas 2-1, 2-2, 2-3. -3 is controlled so that the reception sensitivity from the communication target (wireless tag T) is optimized. In the phased array processing unit 302, the directivity by the antennas 2-1, 2-2, 2-3 is held so as to be strong in only one direction, and the direction is sequentially changed and transmitted to the communication target (wireless tag T). Control is performed (details will be described later). That is, as is well known, the directivity direction is determined from the antenna interval and the phase difference between the transmission signals supplied to the antennas. Therefore, it is necessary to control the phase of the transmission signal supplied to each antenna in accordance with the desired directivity direction.
Further, as a configuration related to the transmission / reception antenna 2-1, in the DSP 100 ′, in addition to the cancel processing unit 301-1, a first cancel control signal output unit 24-1 and a second cancel control signal output unit 28-1. A phased state in which the directivity by the antennas 2-1, 2-2, 2-3 is maintained so as to be strong only in one direction, and the control signal for transmitting to the RFID tag T is generated while changing the direction in sequence. An array control signal output unit 305-1 is provided. The cancel processor 301-1 includes a first cancel signal controller 26-1, a second cancel signal controller 30-1, a demodulator 32-1, a DC component detector 34-1, a received signal amplitude detector 36-. 1 and a first combined signal amplitude detector 38-1.

  In this modified example having such a configuration, the transmission digital signal output from the transmission digital signal output unit 20 based on the function table 40 is analogized by the high-speed D / A converter 42 as described in the above embodiment. It is converted into a signal (sine wave signal). On the other hand, as in the above embodiment, a transmission signal is output from the 90 ° phase shifter 41 based on the signal from the transmission digital signal output unit 20, and this signal is converted into an analog signal by the high-speed transmission signal D / A converter 43 ( Sine wave signal). The second sine wave signal of the transmission signal D / A converter 43 and the first sine wave signal of the transmission signal D / A converter 42 are a first combined sine wave signal generation circuit 80-1 and a second sine wave signal generation circuit 80-1. In addition to being supplied to the combined sine wave signal generation circuit 90-1, it is also supplied to a third combined sine wave signal generation circuit 304-1 (details will be described later).

  Based on the phased array control signal from the phased array processing unit 302, the third synthesized sine wave signal generation circuit 304-1 synthesizes them while controlling the amplitudes of the first and second sine wave signals, A combined sine wave signal whose phase is controlled is generated for each of the antennas 2-1, 2-2, 2-3 (details will be described later). The frequency of the synthesized sine wave signal output from the third synthesized sine wave signal generation circuit 304-1 is increased by the frequency of the local oscillation signal from the local oscillation signal output unit 44 by the first up-converter 46-1, Further, the amplitude is increased in the first amplifying unit 48-1 and modulated with the modulation signal from the modulating unit 22. The transmission signal output from the first amplifying unit 48-1 is supplied to the antenna 2-1 via the transmission / reception separator 50-1, and is transmitted toward the RFID circuit element To as the interrogation wave Fc.

The reflected wave Fr from the RFID circuit element To is received by the antenna 2-1, and the reflected wave Fr via the transmission / reception separator 50-1 is supplied to the first signal combining unit 58-1 as a received signal. Although not shown, the second down converter 74-1, the reception signal A / D converter 76-1, the reception signal amplitude detection unit 36, and the first combined signal amplitude detection unit 38 are the same as those in the above embodiment. Etc. are provided and perform the same function.
The first signal synthesizing unit 58-1 performs the primary cancellation similar to the above embodiment. In other words, the first cancel signal control unit 26-1 determines the phase of the first cancel signal based on the amplitude input from the reception signal amplitude detection unit 36-1 and the amplitude input from the first combined signal amplitude detection unit 38-1. And determine the amplitude. The determined phase and amplitude are input to the first cancel control signal output unit 24-1 and a first cancel control signal is output.

  In the first synthesized sine wave signal generation circuit 80-1, the first cancellation control signal output unit 24-1 (or the lower-speed first cancellation control signal D / A converters 53-1 and 54-1) is used. Based on the first cancel control signal, as in the above embodiment, the first and second sine wave signals are combined while controlling the amplitude of the first and second sine wave signals to generate a primary sine wave signal (first cancel). Signal). The frequency of the first cancel signal output from the first synthesized sine wave signal generation circuit 80-1 is increased by the frequency of the local oscillation signal output from the local oscillation signal output unit 44 by the second up-converter 56-1. This signal and the received signal supplied via the transmission / reception separator 50-1 are combined by the first signal combining unit 58-1, and the sneak signal from the transmission side included in the received signal is removed (or reduced). The

  The first synthesized signal output from the first signal synthesizing unit 58-1 is changed in amplitude by a predetermined gain in the second amplifying unit 60-1, and then the frequency is changed by the first down converter 62-1. The frequency is reduced by the frequency of the local oscillation signal output from the local oscillation signal output unit 44 and supplied to the second signal synthesis unit 66-1 (also supplied to the third amplification unit 68-1 not shown). The first synthesized signal supplied to the third amplifying unit 68-1 is changed in its amplitude and further digitally converted by the first synthesized signal A / D converter 70-1 and then the first synthesized signal amplitude detecting unit. 38-1 to detect the amplitude thereof, and the detected amplitude is supplied to the first cancel signal control unit 26-1 and the second cancel signal control unit 30-1.

  On the other hand, the second cancel signal control unit 30-1 having input the amplitude detection value in the first composite signal amplitude detection unit 38-1 receives the detection value (the amplitude of the received signal after the primary cancellation) and the second composite signal A. Based on the second composite signal from the / D converter 72, the phase and amplitude of the second cancel signal are determined. The second cancel control signal output unit 28-1 outputs a second cancel control signal for generating a second cancel signal having the determined phase and amplitude. The second synthesized sine wave signal generation circuit 90-1 is connected to the second cancellation control signal output unit 28-1 (or the lower-speed second cancellation control signal D / A converters 63-1, 64-1). Based on the second cancel control signal, the second cancel signal is generated by combining the first and second sine wave signals while controlling the amplitude of the first and second sine wave signals.

  The second cancel signal output from the second composite sine wave signal generation circuit 90-1 is the down-converted first composite signal supplied from the first down converter 62-1 and the second signal combiner 66-1. Thus, the sneak signal from the transmission side included in the first synthesized signal is removed (reduced).

  The second synthesized signal output from the second signal synthesizer 66-1 is digitally converted by the second synthesized signal A / D converter 72-1, and then sent to the demodulator 32-1 and the adaptive array processor 303. Supplied. The second combined signal from which the unnecessary signal is removed (reduced) as described above by the adaptive processing unit 303 is adaptively processed, and is combined and demodulated based on the optimal reception directivity having a high signal-to-noise ratio and a small error rate. The information signal of the RFID tag circuit element To is read out. The second combined signal demodulated by the demodulator 32-1 is input to the DC component detector 34-1, and the DC component of the demodulated signal is detected. The detection result is the second cancel signal controller 30-1. To be supplied. Since the information of the RFID circuit element To is read by the adaptive processing unit 303, the demodulation unit 32-1 only performs demodulation for detecting the magnitude of the DC component to be supplied to the second cancel signal control unit 30-1. Done.

  FIG. 10 is a circuit diagram illustrating a detailed configuration of the third synthesized sine wave signal generation circuit 304-1. In FIG. 10, a third synthesized sine wave signal generation circuit 304-1 has a configuration similar to that of the first synthesized sine wave signal generation circuit 80 and the second synthesized sine wave signal generation circuit 90 described above, and the phased array control signal described above. The digital signal from the output unit 305-1 is operated according to the control voltage for amplitude control (amplitude signal: the same applies hereinafter) from the low-speed D / A converter 306-1 obtained by D / A converting the high-speed first signal. The variable attenuator 85 for controlling the amplitude of the first sine wave signal (cosωt) from the transmission signal D / A converter 42, the amplifier 81 for inverting the polarity of the first sine wave signal, and the above The switch 83 that operates according to a polarity switching control signal (polarity signal: the same applies hereinafter) from the phased array control signal output unit 305-1 and switches the inversion / non-inversion of the first sine wave signal, and the phased Are The digital signal from the control signal output unit 305-1 is operated according to the control voltage for amplitude control from the low-speed D / A converter 307-1 obtained by D / A conversion, and the high-speed second transmission signal D / A The variable attenuator 86 for controlling the amplitude of the second sine wave signal (sinωt) from the A converter 43, the amplifier 82 for inverting the polarity of the second sine wave signal, and the phased array control signal. Operates in accordance with the polarity switching control signal from the output unit 305-1 and synthesizes the output from the switch 84 and the variable attenuators 85 and 86 for switching the inversion / non-inversion of the second sine wave signal. And the adder 87 for generating a synthesized sine wave signal.

  With the above configuration, the amplitudes of the first and second sine wave signals are controlled by the variable attenuators 85 and 86 in accordance with the control voltages from the D / A converter 306-1 and the D / A converter 307-1. Then, in accordance with the control signal from the phased array control signal output unit 305-1, the amplifiers 81 and 82 and the switches 83 and 84 switch the polarity of the first and second sine wave signals to be inverted or non-inverted, thereby synthesizing. The amplitude and plus / minus of the previous first and second sine wave signals (sinωt and cosωt) can be freely set, and a synthesized sine wave signal having a desired phase is generated by the adder 87 to generate the second up-converter 46- 1 is output.

  In addition, since the structure and operation | movement demonstrated regarding the antenna 2-1 above are the same also about the other antennas 2-2 and 2-3, each detailed description is abbreviate | omitted.

  According to this modified example of the above configuration and operation, the sneak signal from the transmission side included in the received signals from the antennas 2-1, 2-2, 2-3 is suitably removed (reduced) as in the above embodiment. Therefore, highly sensitive communication can be realized.

  In addition to the above, there are the following effects. In other words, when a digital oscillator is used on the interrogator 1 side and an array antenna composed of a plurality of elements 2-1 to 2-3 is used for transmission as in this modification, it is usually fast for each antenna element. As a result, a large number of DA converters are required, resulting in an increase in cost. On the other hand, in the present embodiment, the first transmission signal D / A converter 42 and the second transmission signal D / A converter 43, which are sine wave generating means, are all antennas (antenna elements) 2-1, 2. The first and second sine wave signals generated by the common sine wave generating means are provided for each of the antennas 2-1 to 2-3. Amplitude control and synthesis are sufficient with the circuits 80-1 to 80-3, the second synthesized sine wave signal generation circuits 90-1 to 90-3, and the third synthesized sine wave signal generation circuits 304-1 to 304-3. That is, even if the number of antenna elements is large, the entire circuit can be constructed at a relatively low cost.

  That is, generally, the first transmission signal D / A converter 42 and the second transmission signal D / A converter 43 need to use expensive D / A converters capable of high-speed processing such as 10.7 MHz, for example. When the first cancellation signal and the second cancellation signal are all generated using an expensive high-speed D / A converter using a function table in addition to the transmission signal, three sets of high-speed D / A for one antenna are used. Since it is necessary to use converters, and this is required for the number of antennas, the interrogator 1 in which an array antenna is configured by a plurality of antennas requires a large number of high-speed D / A converters, which is very complicated. And expensive. On the other hand, the present invention uses an expensive D / A converter that can perform high-speed processing only for the first transmission signal D / A converter 42 and the second transmission signal D / A converter 43. By using a low-speed analog signal that generates an amplitude signal as a control signal for the two sine wave signals, an inexpensive low-speed D / A converter can be connected to the first cancel control signal D / A 53, 54 and the second It can be used to generate the cancel control signals D / A 63 and 64 and the phased array control signals D / A 306 and 307, and the generation of the transmission signal and cancel signal whose amplitude and phase are controlled can be realized at low cost. Since the frequency required for controlling the amplitude and phase is much lower than the frequency of the transmission signal, the configuration of the interrogator 1 becomes simple and can be made extremely inexpensive.

  Note that the adaptive array processing of the above modification is performed only by reception independently of the phased array processing, but the weight determined by the reception adaptive processing in the adaptive array processing unit 303 of the DSP 100 ′ is also used on the transmission side. Thus, the adaptive array process may be executed. That is, an adaptive array control signal output unit similar to the phased array control signal output unit 305 and a composite sine wave signal generation circuit that operates with a control signal in the future are provided, and antennas (antenna elements 2-1 to 2) are provided as composite sine wave signals. A synthesized sine wave signal in which the amplitude and phase for transmitting the directivity according to −3) to the wireless tag T so as to optimize the reception sensitivity from the wireless tag T may be generated.

(2) When the control signal to the composite sine wave signal generation circuit is simplified As described above, the composite sine wave signal generation circuits 80, 90, and 304 are arranged as shown in FIG. 6, FIG. 7, and FIG. Although the circuit is configured to operate by inputting a control signal, the configuration of these circuits is not necessarily limited to this, and the control signal to be input can be simplified.

  FIG. 11 is a circuit diagram showing a detailed configuration of the combined sine wave signal generation circuits 180 and 190 used in such a modification. Components equivalent to those in FIG. 6 are given the same reference numerals, and description thereof will be omitted or simplified as appropriate.

  In FIG. 11, a synthesized sine wave signal generation circuit 180 uses a logic circuit 170 that generates and outputs a control signal as an amplitude control means from an input serial signal, and a serial data signal extracted by the logic circuit 170. Shift register 171 and register 172 as register means for outputting control signals for amplitude control and polarity control of the first and second sine wave signals, and D / A conversion of the control signals for amplitude control Low-speed D / A converters 150 and 160.

  In the above configuration, the control signal line information and the data input to the D / A converters 150 and 151 are transmitted from the first cancel circuit 24 to the logic circuit 170 as serial data. The shift register 171 receives the serial data signal from the logic circuit 170 and converts it into a parallel signal. At this time, when the clock from the clock signal output unit 78 is enabled by the start bit inserted before the serial data and a predetermined bit is input to the shift register 171, the parallel signal of the shift register 171 is input to the register 172. The After a predetermined clock elapses, the clock is invalidated, the data in the register 172 is latched, and the value of each bit (at least part of the parallel signal of the shift register 171) is used as a D / A converter as the amplitude control signal. In addition to being supplied to the variable attenuators 85 and 86 via 150 and 160, they are output to the switches 83 and 84 as the polarity control signals.

  In this configuration, the amplitude and polarity of the first and second sine wave signals are controlled by the amplitude control signal and polarity control signal generated using the signal output from the logic circuit 170 and converted into a parallel signal. The control can be performed with only one signal line from the 1 cancel control signal output unit 24 (or the second cancel circuit 28, the phased array control signal output unit 305).

  FIG. 12 shows first synthesized sine wave signal generation circuits 80-1 to 80-3 and second synthesized sine wave signal generation circuits 90-1 to 90-1 in the circuit configuration of the modified example (1) shown in FIG. 90-3 is a circuit diagram when the configuration of the combined sine wave signal generation circuit 180 of FIG. 11 is applied to the third combined sine wave signal generation circuits 304-1 to 304-3.

  As shown in the figure, by using the combined sine wave signal generation circuit 180 having the configuration shown in FIG. 11, the number of signal lines in the entire circuit is greatly reduced, and the configuration can be simplified.

  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.

1 is a system configuration diagram showing an overall outline of an RFID tag communication system to which an embodiment of the present invention is applied. FIG. 2 is a block diagram illustrating an example of a functional configuration of a wireless tag circuit element provided in the wireless tag illustrated in FIG. 1. It is a functional block diagram showing the functional structure of the interrogator shown in FIG. It is explanatory drawing by the vector display for demonstrating the principle of this invention. It is a figure which shows the example of the sine wave table stored in the function table. It is a circuit diagram showing the detailed structure of a 1st synthetic | combination sine wave signal generation circuit. It is a circuit diagram showing the modification of a synthetic | combination sine wave signal generation circuit. It is a circuit diagram showing the other modification of a synthetic | combination sine wave signal generation circuit. It is a functional block diagram showing the functional structure of the interrogator by the modification applied to the array antenna. It is a circuit diagram showing the detailed structure of a 3rd synthetic | combination sine wave signal generation circuit. It is a circuit diagram showing the detailed structure of the synthetic | combination sine wave signal generation circuit used by the modification which simplified the control signal to a synthetic | combination sine wave signal generation circuit. FIG. 12 is a circuit diagram in a case where the configuration of the combined sine wave signal generation circuit in FIG. 11 is applied to the combined sine wave signal generation circuit in the circuit configuration illustrated in FIG. 9.

Explanation of symbols

1 Interrogator (wireless communication device)
2 Antenna (transmitting means; receiving means)
42 1st transmission signal D / A converter (1st digital-analog converter,
Carrier wave output means, sine wave generation means)
43 Second transmission signal D / A converter (second digital-analog converter,
Carrier wave output means, sine wave generation means)
56 Second upconverter (upconverter means)
58 1st signal synthetic | combination part (multiplexing means)
62 First down converter (down converter means)
72 Second composite signal A / D converter (analog-digital converter)
78 Clock signal output unit (oscillation means)
85,86 Variable attenuator (amplitude control means)
87 Adder (Sine wave synthesis means)
S RFID tag communication system

Claims (13)

A transmission means (2) capable of transmitting a carrier wave for accessing a communication target to the communication target;
Receiving means (2) capable of receiving a transmission signal from the communication object in response to a transmission signal from the transmission means;
A signal generation circuit (80, 90) for generating a cancellation wave (including a secondary cancellation wave) for canceling an unnecessary wave that may be generated based on a transmission signal from the transmission unit at the time of signal reception by the reception unit;
A first sine wave signal as the carrier wave and a second sine wave signal that are different in phase from the first sine wave signal and are combined with the first sine wave signal to generate the cancellation wave are generated. and a sine wave generating means (42, 43) which,
The signal generation circuit (80, 90)
A variable attenuator or a variable gain amplifier for controlling the amplitude of the first and second sine wave signals; and an inverting means capable of switching inversion / non-inversion of the polarity thereof, wherein the first sine wave generating means generates the first Amplitude control means (85, 86) for controlling the amplitude of each of the first and second sine wave signals;
Sine wave synthesizing means for synthesizing the first sine wave signal and the second sine wave signal, the amplitude of which is controlled by the amplitude control means, and generating a synthesized sine wave signal as the cancellation wave (including a secondary cancellation wave) (87) and the wireless communication apparatus according to claim <br/> comprise a. The wireless communication device according to claim 1, wherein
The sine wave generating means includes
Generating the first sine wave signal and the second sine wave signal that are approximately 90 ° out of phase with each other;
The sine wave synthesizing means is
A wireless communication apparatus that generates the combined sine wave signal having an amplitude and a phase different from those of the first and second sine wave signals. The wireless communication device according to claim 2 , wherein
Before Symbol sine wave synthesis means,
A wireless communication apparatus that generates the combined sine wave signal (= first order cancellation wave) having substantially the same amplitude as that of the unnecessary wave and having a phase reversed. The wireless communication device according to claim 3, wherein
The sine wave generating means is a first digital-analog converter and a second digital-analog converter that use a sine wave sampling string as the first sine wave signal and the second sine wave signal. Wireless communication device. The wireless communication device according to claim 3, wherein
Combining means for combining the received signal received by the receiving means and the combined sine wave signal from the sine wave combining means to generate a corrected received signal;
An analog-to-digital converter that digitally converts the corrected reception signal generated by the multiplexing means,
The clock signal input to the first digital-analog converter and the clock signal input to the analog-digital converter are common signals or signals generated from common oscillation means. A wireless communication device. The wireless communication device according to claim 5, wherein
Up-converter means for up-converting the frequency of the combined sine wave signal output from the sine wave combining means;
And a down-converter that down-converts the frequency of the corrected reception signal generated by the multiplexing unit. The wireless communication device according to claim 5 or 6,
The sine wave synthesis means (87 included in 90) is :
Wireless communication device characterized by further generating a pre-Symbol corrected reception signal of the carrier component and substantially the same amplitude in phase the synthesis sine wave signal such that the opposite (= secondary offset wave). The wireless communication apparatus according to claim 1 or 2,
It has multiple antenna elements that perform information communication without contact with the communication target,
The sine wave synthesizing means, as the synthesized sine wave signal, a synthesized sine wave signal whose phase is controlled with respect to each antenna element for transmitting to the communication target while controlling directivity by the plurality of antenna elements. A wireless communication device generated. The wireless communication apparatus according to claim 8, wherein
The sine wave combining means holds at least a phase as the combined sine wave signal so that the directivity by the plurality of antenna elements is strengthened in only one direction and is sequentially changed to be transmitted to the communication target. A wireless communication device that generates a controlled composite sine wave signal. The wireless communication apparatus according to claim 8, wherein
The sine wave synthesizing unit is a synthesized sine wave signal having a controlled amplitude and phase for transmitting the directivity of the plurality of antenna elements to the communication target so that reception sensitivity from the communication target is optimized. A wireless communication device that generates a sine wave signal. The wireless communication apparatus according to any one of claims 8 to 10,
The sine wave generating means is a digital-analog converter using a sine wave sampling string as a sine wave signal. The wireless communication apparatus according to any one of claims 8 to 10,
A radio communication apparatus comprising: up-converter means for up-converting the frequency of the synthesized sine wave signal output from the sine wave synthesis means. The wireless communication apparatus according to any one of claims 1 to 12 ,
The amplitude control means includes
A logic circuit that generates a control signal and outputs it as a serial signal;
The serial signal from the logic circuit is converted into a parallel signal, and a control signal for controlling the amplitude and polarity of the first and second sine wave signals is generated using a part of the value, and the variable attenuator or A wireless communication apparatus further comprising: a variable gain amplifier; and register means for outputting to the inverting means.

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