JP4333450B2 - Information processing apparatus, wireless communication system, and wireless communication method - Google Patents

Description

  The present invention relates to a system for reading electronic price tags attached to tableware in restaurants, merchandise, etc. in stores, a system for reading electronic tag tags attached to articles distributed on goods distribution bases, etc. The present invention relates to an information processing apparatus, a wireless communication system, and a wireless communication method that are suitable for application to a guidance sign reading system for guiding.

  Specifically, when predetermined data is wirelessly communicated by the backscatter communication method, the wireless transceiver includes a carrier wave compensation circuit, and the phase of the carrier wave signal at the time of transmission and the phase of the carrier wave composite signal that forms the response signal at the time of reception And the carrier synthesized signal that is not synchronized with the phase of the carrier signal at the time of transmission is removed based on the comparison result so that the data modulation component of the response signal transmitted from the signal responder can be compensated. The S / N ratio of the response signal returned from the signal responder can be improved.

  In recent years, with the development of semiconductor integrated circuit technology, wireless communication technology has been increasingly applied in the information processing field such as a wireless mouse and an access point, in addition to the communication processing field such as a mobile phone. A tag reader system has been devised as an application of this type of wireless communication technology. This tag reader system wirelessly communicates predetermined data by a backscattering communication (back scattering) method, and is applied to, for example, a system that reads an electronic price tag attached to tableware in a restaurant.

  FIG. 7 is a conceptual diagram of a main part showing a configuration example of a tag reader system 1 as a conventional example. The tag reader system 1 shown in FIG. 7 includes a tag 10 and a tag reader 20 ′, and continuously transmits a carrier wave signal of a predetermined frequency from the tag reader 20 ′ to the tag 10 and scatters from the tag 10 ( It is intended to receive the amplitude-modulated signal coming back and obtain the tag-specific data.

  In FIG. 7, a tag 10 receives a carrier wave signal (interrogation signal) having a frequency of 2.45 GHz, modulates the carrier wave signal with specific data, for example, by amplitude modulation, and a tag amplitude modulated signal (hereinafter simply referred to as amplitude modulation). Response signal Sf (D)) is transmitted. The tag 10 is attached to an identified object 9 such as tableware in a restaurant, for example. The tag 10 includes a reception antenna body 1A, a transmission antenna body 1B, an amplitude modulation section 2, a memory section 3, a clock oscillator 4, and a power supply section 5. Although the antenna bodies 1A and 1B are divided into two for the explanation of the operation, they are actually composed of one antenna body.

  The antenna body 1A receives a carrier wave signal Sf that is an interrogation signal in the tag reader system 1. As the antenna bodies 1A and 1B, loop antennas in which a conductor is wound in a coil shape are used. A power supply unit 5 is connected to the antenna bodies 1A and 1B, and operates to supply induced power based on the carrier signal Sf received by the antenna body 1A to the amplitude modulation unit 2, the memory unit 3, and the clock oscillator 4.

  The memory unit 3 stores, for example, data (DATA) specific to the identified object such as the price of the dish placed on the tableware, and this data is read based on the clock signal (CLK). The data is output to the modulation unit 2. A read only memory (ROM) is used for the memory unit 3. A clock oscillator 4 is connected to the memory unit 3 and operates to oscillate a clock signal having a predetermined frequency and output it to the memory unit 3. The amplitude modulation unit 2 amplitude-modulates the carrier signal Sf based on the data read from the memory unit 3. An antenna body 1B is connected to the amplitude modulation section 2 so as to transmit the response signal Sf (D) after amplitude modulation.

  The tag reader system 1 includes a tag reader 20 ′ in addition to the tag 10 described above. The tag reader 20 'transmits the carrier signal Sf to the tag 10 and receives the response signal Sf (D) returned from the tag 10 for signal processing. Actually, in addition to the response signal Sf (D), an unmodulated carrier wave synthesis signal Sf ′ reflected and returned from the surrounding object is also received by the antenna 13B. That is, the response composite signal Sin including the response signal Sf (D) and the carrier wave composite signal Sf ′ is received.

  The main part of the tag reader 20 'includes an oscillator 11, a transmission unit 12, a transmission antenna body 13A, a reception antenna body 13B, a reception unit 14', and the like. Although the antenna bodies 13A and 13B are described in two parts for the explanation of the operation, they are actually composed of one antenna body. The oscillator 11 generates a carrier signal Sf of 2.45 GHz. The transmitter 11 is connected to the oscillator 11, amplifies the carrier signal Sf based on the output permission signal S1 input from the control terminal 72, and outputs the amplified carrier signal Sf (= Sout) to the transmitting antenna body 13A. To do. The transmitting antenna body 13A radiates the amplified carrier wave signal Sf.

  The receiving unit 14 'receives the response signal Sin at the time of reception and performs data demodulation processing. The receiving unit 14 ′ has a demodulation circuit 40 and a data reading unit 50. The demodulation circuit 40 is connected to the antenna body 13B, demodulates the response signal Sf (D) based on the carrier wave signal Sf, and outputs tag-specific data (DATA). A data reading unit 50 is connected to the demodulation circuit 40, and the data reading unit 50 reads data specific to the tag and outputs it to the output terminal 60. A monitor 16 shown in FIG. 8 is connected to the output terminal 60 through a control device (not shown). The monitor 16 displays tag-specific data read by the data reading unit 50.

  FIG. 8 is a conceptual diagram for explaining the problems of the tag reader system 1. In the tag / reader system 1 shown in FIG. 8, the tag / reader main body 101 includes a monitor 16, a read operation button 171, and the like.

  When the read operation button 171 of the tag reader body 101 is pressed in the tag reader system 1, the amplified carrier signal Sout = Sf is radiated from the antenna body 13A shown in FIG. Sent to tag 10. When the object 90 is present in the surroundings, the carrier wave signal Sf transmitted to the tag 10 reflects the object 90 along the path II, and the carrier wave synthesized signal Sf 'after reflection is received by the tag reader 20'. The tag 10 amplitude-modulates the carrier signal Sf through the path I based on the data.

  On the other hand, the tag reader body 101 receives the response composite signal Sin returned from the tag 10 and performs signal processing. Actually, the response signal Sf (D) based on the carrier wave signal Sf returned from the tag 10 in the path III and the unmodulated carrier wave synthesis signal Sf ′ reflected and returned from the object 90 in the path II become the response synthesized signal Sin. It is included and received by the antenna body 13B shown in FIG. Thus, when the object 90 exists in the surroundings, the carrier wave synthesis signal Sf ′ returned from the surrounding object 90 causes noise.

  In connection with the tag reader system, Patent Document 1 describes a modulation back-scattering wireless communication system. According to this wireless communication system, an interrogator and a remote tag are provided, and an interrogation signal having a predetermined frequency is transmitted from the interrogator to the remote tag. At this time, a narrowband downlink signal is used as the interrogation signal. Further, the interrogator receives the response signal that has been amplitude-modulated by the remote tag and is converted into a broadband uplink signal after amplitude modulation, and the signal is processed. By using such a narrowband downlink signal and a wideband uplink signal, an MBS wireless communication system having a processing gain related to MBS (Modulation Back Scattering) background noise can be provided.

  Further, in relation to a background noise reduction method in this type of system, Patent Document 2 discloses a background noise reduction device. This background noise reduction apparatus includes a demodulator, a frame power measurement circuit, a linear prediction analysis circuit, an inverse filtering circuit, and a subtracter. The frame power measurement circuit inputs a demodulated audio signal (hereinafter referred to as a demodulated signal) from the demodulator, obtains its power level for each frame, and compares it with a predetermined threshold value. As a result of the comparison, if the power level is equal to or lower than the threshold value, the linear prediction analysis circuit receives the demodulated signal and performs linear prediction analysis to obtain a linear prediction coefficient. The inverse filtering circuit obtains a prediction value by performing an inverse filtering process on the demodulated signal based on the linear prediction coefficient. The subtracter is configured to subtract the predicted value from the input demodulated signal. In this way, only the background noise level can be reduced to a predetermined value or less, and the receiver can comfortably talk while using the background noise as part of the information.

Japanese Patent Laid-Open No. 11-239078 (FIG. 3 [0005] to [0016]) JP 07-193519 A (FIG. 1 [0007] to [0029])

  Incidentally, the tag / read system to which the MBS wireless communication system according to the conventional example is applied has the following problems.

  i. As shown in FIG. 8, when the object 90 exists around the tag reader main body 101, the carrier wave composite signal Sf 'reflected from the object 90 and returned is a cause of noise. Therefore, the S / N ratio of the response signal from the tag 10 may be reduced.

  ii. Incidentally, in order to suppress a decrease in the S / N ratio of the response signal transmitted from the tag 10, a method of combining the wireless communication system described in Patent Document 1 and the background noise reduction device described in Patent Document 2 is conceivable. Since it is difficult to derive a configuration for removing the carrier wave composite signal Sf ′ that has been reflected back from the object 90 simply by combining the two technical ideas, data of the original response signal transmitted from the tag 10 Compensating for the modulation component involves difficulties.

  Accordingly, the present invention solves such a conventional problem, and compensates for the data modulation component of the response signal transmitted from the signal responder when predetermined data is wirelessly communicated by the backscatter communication method. An object of the present invention is to provide an information processing apparatus, a wireless communication system, and a wireless communication method that can improve the S / N ratio of a response signal returned from a signal responder.

The issues mentioned above
And a transmission unit for transmitting a carrier signal of non-modulation of a predetermined frequency to the signal response of Backward scattering communication system, a response signal modulated by predetermined data carrier signal transmitted from the transmitting unit to the signal response member , and a signal processing unit for receiving and processing a response signal that has been scattered from the signal response body, the signal processing section is provided a carrier compensation circuit, the carrier recovery circuit includes a phase of the carrier signal at the time of transmission The phase difference of the carrier signal at the time of reception, in which the phase difference information is detected by comparing the phase of the carrier signal at the time of reception, and the phase difference is generated with respect to the carrier signal at the time of transmission based on the information of the phase difference. A phase synchronization detection unit that detects an estimated value, and a phase difference estimation value of a carrier signal at the time of reception input from the phase synchronization detection unit, and a carrier signal at the time of reception that causes a phase shift with respect to the carrier signal at the time of transmission Amplitude control to eliminate And an amplitude control unit detects a second phase difference information from the difference between the phase of the carrier signal at the time of transmission and the phase of the compensated carrier signal at the time of reception, and the phase detection circuit Phase difference comparison for comparing the second phase difference information detected by the circuit and the phase difference estimation value to detect an amplitude estimation value of the carrier signal at the time of reception that causes a phase shift with respect to the carrier signal at the time of transmission An amplitude component for adjusting the amplitude of the carrier signal at the time of transmission and the phase thereof , from the amplitude estimation value and the phase difference estimation value of the carrier signal at the time of reception detected by the circuit and the phase difference comparison circuit An amplitude adjustment circuit that detects a phase difference component, a phase control circuit that controls the phase and amplitude of a carrier wave signal during transmission based on the amplitude component and the phase difference component detected by the amplitude adjustment circuit, and a phase control circuit By It is solved by information processing apparatus including an arithmetic circuit for subtracting the carrier signal at the transmission amplitude and phase is controlled from the carrier signal during reception.

According to the information processing apparatus of the present invention, a carrier signal having a predetermined frequency is transmitted to a signal responder of a backscatter communication method, and a response signal obtained by modulating the carrier signal with predetermined data is received from the signal responder and processed. When transmitting, a transmission part transmits a carrier wave signal to a signal response body. The signal processing unit receives and processes the response signal scattered from the signal responder. On the premise of this, the carrier wave compensation circuit provided in the signal processing unit detects the information of the first phase difference from the difference between the phase of the carrier wave signal at the time of transmission and the phase of the carrier wave signal at the time of reception. Based on the first phase difference information, a phase difference estimation value of the carrier signal at the time of reception that causes a phase shift with respect to the carrier signal at the time of transmission is detected, and the phase of the carrier signal at the time of transmission and the compensated carrier wave The second phase difference information is detected from the difference from the phase of the signal, and the detected second phase difference information and the phase difference estimated value are compared with each other to detect a phase shift with respect to the carrier signal at the time of transmission. detecting an amplitude estimate of the carrier signal during reception resulted from the amplitude estimates and the phase difference estimated value of the detected carrier signal at the time of reception was here, the amplitude for adjusting the amplitude of the carrier signal during transmission detecting a phase difference between a component for adjusting the component and its phase, Controlling the phase and amplitude of the carrier signal at the time of transmission based on an amplitude component and a phase difference component is detected in this transmission, the carrier signal during reception, by subtracting the carrier signal at the time of transmission of controlled amplitude and phase The carrier signal at the time of reception that causes a phase shift with respect to the carrier signal at the time is removed .

For example, the phase synchronization detection unit compares the phase of the carrier signal at the time of transmission with the phase of the carrier signal at the time of reception , and the amplitude of the carrier signal at the time of reception that causes a phase shift with respect to the carrier signal at the time of transmission. Detect an estimate . The amplitude control unit removes the carrier wave signal at the time of reception that causes a phase shift from the carrier wave signal at the time of transmission detected by the phase synchronization detection unit. At this time, the phase detection circuit detects the second phase difference information from the difference between the phase of the carrier signal at the time of transmission and the phase of the compensated carrier signal at the time of reception. The phase difference comparison circuit compares the information of the second phase difference detected by the phase detection circuit and the phase difference estimation value, and the amplitude of the carrier signal at the time of reception that causes a phase shift with respect to the carrier signal at the time of transmission. Detect an estimate. The amplitude adjusting circuit adjusts the amplitude component and the phase for adjusting the amplitude of the carrier signal at the time of transmission from the amplitude estimated value and the phase difference estimated value of the carrier signal at the time of reception detected by the phase difference comparison circuit. The phase difference component of is detected. The phase control circuit controls the phase and amplitude of the carrier signal at the time of transmission based on the amplitude component and the phase difference component detected by the amplitude adjustment circuit . Arithmetic circuitry operates to draw to the carrier signal or al difference when receiving a carrier signal at the time of transmission of the amplitude and phase is controlled by the phase control circuit.

  Therefore, since the data modulation component of the response signal transmitted from the signal responder can be compensated so as to eliminate the carrier wave signal reflected from the surrounding object, the S of the response signal scattered from the signal responder can be compensated. / N ratio can be improved. Thus, highly reliable data that is not affected by interference noise can be demodulated.

Wireless communication system according to the present invention receives a carrier signal unmodulated Jo Tokoro frequency, and the signal response of the backscatter communication method for transmitting a response signal to the carrier signal modulated by predetermined data signals responsive it transmits the carrier signal to the body, and a data processing device with the wireless transmission and reception functions of the information processing by receiving a response signal that has been scattered from the signal response body, the information processing apparatus, the carrier compensation circuit The carrier wave compensation circuit is provided to detect phase difference information by comparing the phase of the carrier wave signal at the time of transmission with the phase of the carrier wave signal at the time of reception, and based on the information on the phase difference, A phase synchronization detection unit that detects a phase difference estimation value of a carrier signal at the time of reception in which a phase shift has occurred, and a phase difference estimation value of the carrier signal at the time of reception from the phase synchronization detection unit Carrier signal An amplitude control unit that removes a carrier signal at the time of reception that causes a phase shift, and the amplitude control unit is based on the difference between the phase of the carrier signal at the time of transmission and the phase of the carrier signal after compensation at the time of reception. The phase detection circuit for detecting the second phase difference information is compared with the second phase difference information and the phase difference estimated value detected by the phase detection circuit, and the phase shift is made with respect to the carrier signal at the time of transmission. A phase difference comparison circuit for detecting an amplitude estimation value of the carrier signal at the time of reception , and a carrier wave at the time of transmission from the amplitude estimation value and the phase difference estimation value of the carrier signal at the time of reception detected by the phase difference comparison circuit. an amplitude adjustment circuit for detecting a phase difference component for adjusting the amplitude component and the phase for adjusting the amplitude of the signal, the carrier at the time of transmission based on the amplitude amplitude component detected by the adjustment circuit and the phase difference component Signal A phase control circuit for controlling the phase and amplitude, the by the phase control circuit the amplitude and phase is to also include a calculation circuit to subtract from the carrier signal when receiving a carrier signal at the time of transmission which is controlled.

According to the wireless communication system of the present invention, when predetermined data is wirelessly communicated by the backscatter communication method, the information processing apparatus according to the present invention is applied to receive a carrier signal of a predetermined frequency, For example, a signal responder that modulates data and transmits a response signal is attached to the object to be identified. A carrier wave signal is transmitted from the information processing apparatus with a wireless transmission / reception function to the signal responder, and the information processing apparatus receives the response signal scattered from the signal responder and performs signal processing. Based on this assumption, the carrier compensation circuit provided in the information processing apparatus detects the first phase difference information from the difference between the phase of the carrier signal at the time of transmission and the phase of the carrier signal at the time of reception. Based on the first phase difference information, a phase difference estimation value of the carrier signal at the time of reception that causes a phase shift with respect to the carrier signal at the time of transmission is detected, and the phase of the carrier signal at the time of transmission and the compensated carrier wave The second phase difference information is detected from the difference from the phase of the signal, and the detected second phase difference information and the phase difference estimated value are compared with each other to detect a phase shift with respect to the carrier signal at the time of transmission. detecting an amplitude estimate of the carrier signal during reception resulted from the amplitude estimates and the phase difference estimated value of the detected carrier signal at the time of reception was here, the amplitude for adjusting the amplitude of the carrier signal during transmission components and detects a phase difference component for adjusting the phase Here the phase and amplitude of the carrier signal during transmission is controlled based on the detected amplitude component and a phase difference component transmitted from the carrier signal during reception, by subtracting the carrier signal at the time of transmission of controlled amplitude and phase The carrier signal at the time of reception that causes a phase shift with respect to the carrier signal at the time is removed.

  Therefore, the data modulation component included in the response signal transmitted from the signal responder can be compensated so as to eliminate the unmodulated carrier wave signal reflected from the surrounding object, and thus it is scattered from the signal responder. The S / N ratio of the response signal can be improved. Thus, highly reliable data that is not affected by interference noise can be demodulated.

A wireless communication method according to the present invention includes a signal responder that receives an unmodulated carrier signal having a predetermined frequency, modulates the carrier signal with predetermined data, and transmits a response signal to the object to be identified. The backscatter communication type wireless communication system that transmits a carrier wave signal to a signal responder attached to the receiver and receives the response signal returned from the signal responder and performs signal processing is used to transmit the phase of the carrier signal at the time of transmission. And the phase difference of the carrier signal at the time of reception is detected, information on the first phase difference is detected, and a phase shift occurs with respect to the carrier signal at the time of transmission based on the information on the first phase difference The phase difference estimated value of the carrier signal is detected, the second phase difference information is detected from the difference between the phase of the carrier signal at the time of transmission and the phase of the carrier signal after compensation, and the second phase difference detected here is detected. Phase difference information and position Comparing the difference between the estimated value, and detecting an amplitude estimate of the carrier signal during reception caused a phase shift relative to the carrier signal at the time of transmission, the amplitude estimate and position of the detected carrier signal at the reception was here From the phase difference estimated value, an amplitude component for adjusting the amplitude of the carrier wave signal at the time of transmission and a phase difference component for adjusting the phase thereof are detected, and based on the detected amplitude component and phase difference component at the time of transmission The carrier wave at the time of reception in which the phase difference and the amplitude of the carrier wave signal at the time of transmission are subtracted from the carrier wave signal at the time of transmission by subtracting the carrier wave signal at the time of transmission controlled from the carrier wave signal at the time of transmission. it's also that to remove the signal.

  According to the wireless communication method of the present invention, when predetermined data is wirelessly communicated by the backscatter communication method, the data modulation component of the response signal transmitted from the signal responder can be compensated. It is possible to improve the S / N ratio of the response signal scattered from. Therefore, it is possible to demodulate highly reliable data that is not affected by interference noise caused by an unmodulated carrier wave signal reflected from a peripheral object.

According to the information processing apparatus of the present invention, when wirelessly communicating predetermined data using the backscatter communication method, the signal processing unit includes a carrier wave compensation circuit, and the phase of the carrier wave signal at the time of transmission, detects the phase difference information by comparing the carrier signal phase, detecting a phase difference between the estimated value of the carrier signal during reception caused a phase shift relative to the carrier signal at the time of transmission based on the information of the phase difference Then, the amplitude component for adjusting the amplitude of the carrier signal at the time of transmission and the phase difference component for adjusting the phase thereof are detected from the amplitude estimation value and the phase difference estimation value of the carrier signal at the time of reception detected here. Then, based on the detected amplitude component and phase difference component, the phase and amplitude of the carrier signal at the time of transmission are controlled, and the carrier signal at the time of transmission whose amplitude and phase are controlled is subtracted from the carrier signal at the time of reception. Sent by Is made to remove the carrier signal at the time of reception caused a phase shift relative to the carrier signal when.

  With this configuration, the carrier component of the response signal transmitted from the signal responder can be compensated, so that the S / N ratio of the response signal scattered from the signal responder can be improved. Therefore, it is possible to demodulate highly reliable data that is not affected by the interference noise caused by the carrier wave signal reflected from the peripheral object.

According to the wireless communication system and the wireless communication method according to the present invention, when predetermined data is wirelessly communicated by the backscatter communication method, the information processing apparatus with the wireless transmission / reception function according to the present invention is applied, and the signal processing unit thereof Is equipped with a carrier wave compensation circuit , detects the phase difference information by comparing the phase of the carrier wave signal at the time of transmission with the phase of the carrier wave signal at the time of reception , and based on the information on the phase difference, The phase difference estimated value of the carrier signal at the time of reception that causes a phase shift with respect to the signal is detected, and the carrier signal at the time of transmission is detected from the amplitude estimated value and the phase difference estimated value of the carrier signal at the time of reception detected here . Detecting the amplitude component for adjusting the amplitude and the phase difference component for adjusting the phase thereof , and controlling the phase and amplitude of the carrier signal at the time of transmission based on the detected amplitude component and phase difference component ; When receiving From the carrier signal, it is adapted to divided the carrier signal at the time of reception caused a phase shift relative to the carrier signal at the time of transmission by subtracting the carrier signal at the time of transmission of controlled amplitude and phase.

  With this configuration, the carrier signal of the response signal transmitted from the signal responder can be compensated, so that the S / N ratio of the response signal scattered from the signal responder can be improved. Therefore, it is possible to demodulate highly reliable data that is not affected by the interference noise caused by the carrier wave signal reflected from the peripheral object.

  Subsequently, an embodiment of an information processing apparatus, a wireless communication system, and a wireless communication method according to the present invention will be described with reference to the drawings.

  FIG. 1 is a perspective view showing a configuration example of a tag reader system 100 with a carrier wave compensation function as an embodiment according to the present invention.

  In this embodiment, when predetermined data is wirelessly communicated by the backscatter communication method, an information processing apparatus with a wireless transmission / reception function is provided with a carrier wave compensation circuit, and the phase of a carrier wave signal at the time of transmission and the synthesized wave at the time of reception are provided. The data modulation component of the response signal transmitted from the signal responder is compared with the phase of the carrier signal, and the synthesized wave carrier signal that is not synchronized with the phase of the carrier signal at the time of transmission is removed based on the comparison result. And the S / N ratio of the response signal returned from the signal responder can be improved.

  A tag reader system 100 with a carrier compensation function shown in FIG. 1 is an example of a wireless communication system, and is a system that wirelessly communicates predetermined data by a backscatter communication system. This system 100 is a system that reads electronic price tags attached to tableware in restaurants, merchandise, etc. in stores, a system that reads electronic tag tags attached to articles distributed on an article distribution base, etc., walking of visually impaired people The present invention is suitable for application to a guidance sign reading system for guiding

  In FIG. 1, a tag reader system 100 includes a tag 10 as an example of a signal responder and a tag reader 20 with a wireless transmission / reception function as an example of an information processing apparatus. The tag reader 20 includes an antenna body 13, a monitor 16, a read operation button 17, and the like in the reader body. In this example, when the read operation button 17 is pressed, a carrier wave signal (question signal) Sf having a predetermined frequency, for example, 2.45 GHz, is radiated from the antenna body 13 to the tag 10. In FIG. 1, the carrier wave signal Sf is indicated by a one-dot chain line.

  The tag 10 receives the carrier signal Sf, performs a predetermined modulation process on the carrier signal Sf with specific data, and spreads the tag modulation signal (hereinafter also simply referred to as a response signal Sf (D)) after the modulation process ( Send). In FIG. 1, the response signal Sf (D) is indicated by a wavy line. What is actually received by the antenna 13 is combined with the carrier signal Sf ′ reflected from the surrounding object in addition to the response signal Sf (D). The tag 10 is used by being attached to a predetermined identified object 9. The tag 10 is used as an electronic price tag or an electronic tag, and is attached to an identified object 9 such as tableware in a restaurant or a product in a store. The tag 10 includes an IC chip 10 ′ and a loop antenna body 1. The IC chip 10 ′ and the antenna body 1 are integrally formed (modulated) into a flat plate shape using a resin or the like, and attached to each tableware or product.

  FIG. 2 is a block diagram illustrating an example of an internal configuration at the time of transmission / reception in the tag reader system 100. It should be noted that the antenna body 1 of the tag 10 and the antenna body 13 of the tag reader 20 shown in FIG. 1 are used for the transmission and reception antennas 1A, 1B and 13A, in order to clearly explain the principle of the tag reader. 13B is expanded and described in two. In the tag reader system 100 shown in FIG. 2, the tag 10 receives a carrier signal Sf having a predetermined frequency, modulates the carrier signal Sf with specific data (DATA), for example, and responds after amplitude modulation. A signal Sf (D) is transmitted.

  In this example, the tag 10 includes a reception antenna body 1A, a transmission antenna body 1B, an amplitude modulation section 2, a memory section 3, a clock oscillator 4, and a power supply section 5. The amplitude modulation unit 2, the memory unit 3, the clock oscillator 4, and the power supply unit 5 are integrated into a semiconductor integrated circuit to form an IC chip 10 '. The antenna body 1A receives a carrier wave signal Sf that is an interrogation signal in the tag reader system 100. As the antenna bodies 1A and 1B, loop antennas in which a conductor is wound in a coil shape are used. A power supply unit 5 (also simply referred to as a power supply unit) is connected to the antenna bodies 1A and 1B, and induced power based on the carrier wave signal Sf received by the antenna body 1A is transmitted to the amplitude modulation unit 2, the memory unit 3, and the clock oscillator 4. Operates to supply.

  In the memory unit 3, for example, the price of the dish placed on the tableware and the data (code data etc .; DATA) specific to the identified object added to the clothing, home appliances, etc. are recorded, and this data is stored as a clock signal ( CLK), and the data is output to the amplitude modulation section 2. As the memory unit 3, a read only memory (ROM) or an electrically programmable read only memory (EEPROM) is used. A clock oscillator 4 is connected to the memory unit 3 and operates to oscillate a clock signal having a predetermined frequency and output it to the memory unit 3. The amplitude modulation unit 2 amplitude-modulates the carrier signal Sf based on the data read from the memory unit 3. The carrier signal Sf amplitude-modulated with the data is the response signal Sf (D). An antenna body 1B is connected to the amplitude modulator 2, and the response signal Sf (D) after amplitude modulation is scattered (transmitted).

  In addition to the tag 10 described above, the tag reader system 100 includes a tag reader 20 with a wireless transmission / reception function, which is an example of an information processing apparatus. The tag reader 20 transmits the carrier signal Sf to the tag 10 and receives the response signal Sf (D) scattered from the tag 10 for signal processing. The tag reader 20 includes an oscillator 11, a transmission unit 12, a transmission antenna body 13A, a reception antenna body 13B, a reception unit 14, a control device 15, an operation unit 16, a monitor 17, and a power supply unit 18. Yes.

  The oscillator 11 generates a carrier signal Sf (= cosωt) of 2.45 GHz that is an example of a predetermined frequency. The transmitter 11 is connected to the oscillator 11, amplifies the carrier signal Sf based on the output permission signal S1 from the control device 15, and outputs the amplified carrier signal Sf to the transmitting antenna body 13A. For example, the output permission signal S1 is permitted to be transmitted at a high level and is not permitted to be transmitted at a low level. The transmitting antenna body 13A radiates the amplified carrier wave signal Sf. The receiving unit 14 receives the response composite signal Sin at the time of reception and performs data demodulation processing. The response composite signal Sin at the time of reception includes an unmodulated carrier wave signal Sf ′ reflected from surrounding objects and a response signal Sf (D) from the tag 10.

  The receiving unit 14 includes, for example, a carrier compensation circuit 30, a demodulation circuit 40, and a data reading unit 50. The carrier wave compensation circuit 30 has a function of compensating the data modulation component by erasing the unmodulated carrier wave synthesis signal Sf ′ reflected from an object other than the tag. For example, the carrier wave compensation circuit 30 compares the phase of the carrier wave signal Sf at the time of transmission with the phase of the response composite signal Sin as an example of the carrier wave signal at the time of reception, and the carrier wave not synchronized with the phase of the carrier wave signal Sf at the time of transmission. The combined signal Sf ′ operates so as to be removed based on the comparison result. An example of the internal configuration of the carrier wave compensation circuit 30 will be described with reference to FIG.

  A demodulation circuit 40 is connected to the carrier wave compensation circuit 30. The demodulation circuit 40 demodulates the response signal Sf (D) based on the carrier wave signal Sf and outputs tag-specific data (DATA). A data reading unit 50 is connected to the demodulation circuit 40, and the data reading unit 50 reads data specific to the tag.

  In this example, the control unit 15 is connected to the data reading unit 50, and the monitor 16 and the operation unit 17 are connected to the control unit 15. A CPU is used for the control device 15. The monitor 16 displays the price, name, etc. based on the unique data of the identified object 9 read from the tag 10. The price, name, and the like are displayed based on the display data D2 after the control device 15 that has input the unique data of the identified object 9 performs data conversion.

  The operation unit 17 is operated to instruct the control device 15 to read data when reading unique data such as price and name from the identified object 9. Operation data D3 indicating a reading instruction is output from the operation unit 17 to the control device 15. The control device 15 controls the transmission unit 12 based on the operation data D3. For example, the control device 15 outputs the output permission signal S1 to the transmission unit 12, and controls the output of the transmission unit 12 so as to transmit the carrier signal Sf based on the output permission signal S1.

  The power supply unit 5 supplies power to the oscillator 11, the transmission unit 12, the control device 15, the monitor 16, the operation unit 17, the carrier wave compensation circuit 30, the demodulation circuit 40, and the data reading unit 50 described above. In FIG. 2, description of power supply wiring is omitted.

3A to 3C are vector diagrams showing examples of operations of the carrier signal Sf, the response signal Sf (D), and the carrier combined signal Sf ′ handled by the carrier compensation circuit 30. FIG.
A carrier wave signal Au (vector symbol is omitted) shown in FIG. 3A is a signal reflected from surrounding objects when, for example, the carrier wave signal Sf having an amplitude of “3” at the time of transmission is used as a reference. The carrier signal Sf and the carrier signal Au have a phase difference θu. The amplitude constantly fluctuates, but when a certain moment is captured, for example, it is attenuated to “2.5” (see FIG. 5B). The response signal Sf (D) shown in FIG. 3B is a tag modulation signal obtained by amplitude modulating the carrier wave signal Sf, and has a data modulation component and a carrier wave component Ad. The carrier component Ad and the carrier signal Sf have a phase difference θd. The amplitude of the carrier wave component Ad is attenuated to, for example, “2.0” when a certain moment is captured (see FIG. 5C).

  3C is a vector synthesis component of the carrier component Ad of the response signal Sf (D) and the carrier signal Au reflected from the surrounding object, and a noise component (noise) is obtained. It is to be made. The amplitude has expanded to, for example, “4.5” when a certain moment is captured (see FIG. 6C).

  The carrier wave compensation circuit 30 operates so as to remove noise components that could not be removed from the response composite signal Sin at the time of reception. At the time of reception, the antenna 13B reflects the carrier wave composite signal Sf ′ shown in FIG. 3C reflected from surrounding objects, the data modulation component of the response signal Sf (D) shown in FIG. It is considered that a response composite signal Sin including

  The noise component in the response composite signal Sin at the time of reception is considered to be composed of an unmodulated carrier signal Au and a carrier component Ad of the response signal Sf (D). In addition, it is considered that the phase of the carrier wave signal Au and the response signal Sf (D) from the tag 10 are out of phase (not synchronized) when a reflective object is present. Therefore, in this tag reader system 100, in order to extract the original response signal Sf (D) obtained by amplitude modulating the carrier wave signal Sf, the response composite signal Sin (= Sf () input to the antenna 13B at the time of reception is obtained. It is only necessary to remove the carrier combined signal Sf ′ from D) and Sf ′).

FIG. 4 is a block diagram showing an example of the internal configuration of the carrier wave compensation circuit 30. The carrier compensation circuit 30 illustrated in FIG. 4 includes a phase synchronization detection unit 31 and an amplitude control unit 32.
In FIG. 4, the phase synchronization detection unit 31 is a circuit that tracks the phase of the response composite signal Sin including the carrier composite signal Sf ′ and the response signal Sf (D), and the carrier signal Sf at the time of transmission shown in FIG. 3C. And the phase difference θr between the received carrier wave composite signal Sf ′ and the received carrier wave signal Sf ′. For example, the phase of the carrier signal Sf at the time of transmission (reference = 0) is compared with the phase of the carrier signal Sf ′ at the time of reception. This is to detect the carrier combined signal Sf ′ that is not synchronized with the phase of the carrier signal Sf at the time of transmission.

  The phase synchronization detection unit 31 includes, for example, a phase detection circuit 41, a phase difference comparison circuit 42, an LPF circuit 43, and a phase difference output circuit 44. The phase detection circuit 41 is connected to the transmission unit 12 and the receiving antenna body 13B, and receives the response composite signal Sin at the time of reception and the carrier signal Sf at the time of transmission to detect the phase difference θr. . For example, in the phase detection circuit 41, the frequency component of the carrier signal Sf is referenced (cheated) from the oscillator 11, and the phase of the carrier composite signal Sf ′ of the response composite signal Sin at the time of reception and the phase of the carrier signal Sf from the oscillator 11 are obtained. Are compared. From the comparison result, the phase difference θr shown in FIG. 3C is detected.

  A phase difference comparison circuit 42 is connected to the phase detection circuit 41. The phase difference comparison circuit 42 compares the output of the phase difference output circuit 44 with the phase difference θr of the phase detection circuit 41 and locks it to the carrier composite signal Sf ′ that is not synchronized with the carrier signal Sf at the time of transmission. A signal (DC component) Sd is output. For the phase detection circuit 41 and the phase difference comparison circuit 42, for example, a multiplier is used.

  Further, an LPF circuit 43 is connected to the phase difference comparison circuit 42. The LPF circuit 43 filters the synchronization detection signal Sd and outputs a phase difference estimation voltage Vd. The phase difference estimation voltage Vd is a DC voltage for estimating the phase difference θr of the carrier combined signal Sf ′ that is not synchronized with the carrier signal Sf at the time of transmission. A phase difference output circuit 44 is connected to the LPF circuit 43 so as to output a phase difference estimated value θr ′ based on the phase difference estimated voltage Vd to the phase difference comparison circuit 42 and the amplitude controller 32.

  As described above, the phase synchronization detection unit 31 detects and compares the phase difference θr between the carrier signal Sf at the time of transmission and the carrier signal Sf ′ at the time of reception, and estimates the phase difference θr by the primary loop. The phase difference estimated value θr ′ is output to the phase difference comparison circuit 53 and the amplitude adjustment circuit 55 of the amplitude control unit 32.

  The amplitude control unit 32 is a circuit that tracks the amplitude of the carrier combined signal Sf ′ in which the carrier signal Au reflected from the surrounding object and the carrier component Ad of the response signal Sf (D) from the tag 10 are combined. Thus, the amplitude of the carrier combined signal Sf ′ at the time of reception is reproduced. The amplitude controller 32 operates to remove the carrier combined signal Sf ′ from the response combined signal Sin at the time of reception.

  For example, the amplitude control unit 32 reverses the received carrier composite signal Sf ′ reproduced here and adds it to the response composite signal Sin, so that the response composite signal Sin at the reception The influence of the carrier wave signal Au reflected from the object and the carrier wave component Ad of the response signal Sf (D) is removed, and only the response signal Sf (D) from the tag 10 is obtained.

  The amplitude control unit 32 includes, for example, an arithmetic circuit 51, a phase detection circuit 52, a phase difference comparison circuit 53, an LPF circuit 54, an amplitude (level) adjustment circuit 55, and a phase control circuit 56. The arithmetic circuit 51 is connected to the antenna body 13B and the phase control circuit 56, and operates to subtract (subtract) the carrier combined signal Sf ′ phase-controlled by the phase control circuit 56 from the response combined signal Sin at the time of reception. . In this example, the signal obtained by subtracting the carrier combined signal Sf ′ from the response combined signal Sin is the response signal Sf (D) of the tag 10.

  In order to obtain such a response signal Sf (D) of the tag 10, a phase detection circuit 52 is connected to the arithmetic circuit 51. The phase detection circuit 52 inputs the carrier wave signal Sf at the time of transmission and the output of the arithmetic circuit 51, that is, the carrier wave synthesis signal Sf ′ until the response signal Sf (D) is extracted from the response synthesis signal Sin at the time of reception. Thus, the phase difference θr between the carrier combined signal Sf ′ and the carrier signal Sf at the time of transmission is detected. For example, in the phase detection circuit 52, the frequency component of the carrier wave signal Sf is referred (cheated) from the oscillator 11 in the same manner as the phase synchronization detection unit 31, and the phase of the carrier wave synthesis signal Sf ′ of the response synthesized signal Sin at the time of reception, The phase of the carrier signal Sf from the oscillator 11 is compared. From the comparison result, the phase difference θr shown in FIG. 3C is detected.

  A phase difference comparison circuit 53 is connected to the phase detection circuit 52. The phase difference comparison circuit 53 receives the phase difference estimation value θr ′ from the phase difference output circuit 44 and the output signal of the phase detection circuit 52, that is, the phase difference θr of the carrier wave synthesis signal Sf ′ at the time of reception. The phase difference estimated value θr ′ is compared with the phase difference θr of the carrier combined signal Sf ′. Then, the phase difference comparison circuit 53 outputs an amplitude adjustment signal (DC component) Sa for controlling the amplitude while being locked to the carrier wave composite signal Sf ′ at the time of reception.

  Further, an LPF circuit 54 is connected to the phase difference comparison circuit 53. The LPF circuit 54 filters the amplitude adjustment signal Sa output from the phase difference comparison circuit 53 and outputs an amplitude estimated value Va. The amplitude estimation value Va is a DC voltage for estimating the amplitude value of the carrier combined signal Sf ′ that is not synchronized with the phase of the carrier signal Sf at the time of transmission.

  An amplitude adjustment circuit 55 is connected to the LPF circuit 54. The amplitude adjustment circuit 55 receives the amplitude estimation value Va output from the LPF circuit 54 and the phase difference estimation value θr ′ output from the phase difference output circuit 44, and receives the phase difference of the carrier combined signal Sf ′ at the time of reception. The amplitude is adjusted according to the estimated value θr ′, and the amplitude component and the phase difference component after the amplitude adjustment are output. The amplitude component Ax and the phase difference component θx are for removing the carrier combined signal Sf ′ from the response combined signal Sin.

  A phase control circuit 56 is connected to the amplitude adjustment circuit 55. The phase control circuit 56 receives the carrier wave signal Sf at the time of transmission from the oscillator 11, and receives the phase difference component θx and the amplitude component Ax for removing the carrier wave synthesis signal Sf ′ from the amplitude adjustment circuit 55. The phase control circuit 56 controls the phase and amplitude of the carrier signal Sf output from the oscillator 11 on the basis of the phase difference component θx and the amplitude component Ax output from the amplitude adjustment circuit 55, and generates the carrier combined signal Sf ′. create. The carrier combined signal Sf ′ created by this phase and amplitude control is output from the phase control circuit 56 to the arithmetic circuit 51. For example, a multiplier is used for the phase detection circuit 52, the phase difference comparison circuit 53, the amplitude adjustment circuit 55, and the phase control circuit 56.

  This carrier combined signal Sf ′ includes the carrier signal Au reflected from the surrounding object at the time of reception shown in FIG. 3A and the carrier component Ad included in the response signal Sf (D) shown in FIG. 3B. It is a signal whose phase is shifted from the carrier wave signal Sf at the time of transmission. In this example, the phase control loop is locked when the phase difference estimated value θr ′ becomes equal to the phase difference θr of the carrier combined signal Sf ′, and the carrier combined signal Sf ′ is removed from the response combined signal Sin at the time of reception. Processing can be completed. The phase control loop process is repeatedly executed until the phase difference estimated value θr ′ matches the phase difference θr of the carrier wave composite signal Sf ′.

  As described above, the arithmetic circuit 51 operates to subtract (subtract) the above-described carrier wave composite signal Sf ′ from the response composite signal Sin at the time of reception. The arithmetic circuit 51 outputs only the response signal Sf (D) amplitude-modulated by the carrier signal Sf at the time of transmission to the demodulation circuit 40. The demodulation circuit 40 demodulates the response signal Sf (D) based on the carrier signal Sf and outputs tag-specific data (DATA).

  Next, the wireless communication method according to the present invention will be described. 5A to 5C are waveform examples of the carrier signal Sf and the carrier signals Au and Ad having a phase shift, and FIGS. 6A to 6C are diagrams illustrating waveform examples of main parts in the tag reader system 100, respectively. 6A is tag-specific data, FIG. 6B is a response signal Sf (D) that is amplitude-modulated based on the carrier signal Sf, and FIG. 6C is a diagram showing the response signal Sf (D) and the carrier synthesis signal sf ′ for convenience. It is a figure which shows each the example of a waveform drawn in piles. Each waveform is described by capturing a moment and extending the state for a long time. In practice, the amplitude varies with time, resulting in a complex waveform.

  In this embodiment, in the receiving unit 14 of the tag reader 20, the carrier compensation circuit 30 is arranged before the data reading unit 50, for example, before the demodulating circuit 30. A tag 10 that receives a carrier signal Sf of 2.45 GHz, modulates the carrier signal Sf with predetermined data and transmits a response signal Sf (D) is attached to the identified object 9. It is assumed that the carrier wave signal Sf is transmitted to the tag 10 attached to the identified object 9 and the response synthesized signal Sin returned from the tag 10 is received by the tag reader 20 for signal processing ( Backscatter communication method wireless communication method).

  In the carrier wave compensation circuit 30 described above, the phase of the carrier wave signal Sf at the time of transmission is compared with the phase of the carrier wave signal Sf ′ at the time of reception. The carrier combined signal Sf ′ that is not synchronized with the phase of the carrier signal Sf at the time of transmission is removed based on the comparison result.

  Under this operating condition, a 2.45 GHz carrier wave signal Sf shown in FIG. 5A is generated by the oscillator 11 shown in FIG. The carrier signal Sf generated by the oscillator 11 is output to the transmitter 12. The carrier signal Sf has, for example, an amplitude “3”. The transmission unit 12 amplifies the carrier signal Sf to an amplitude “3” or more based on the output permission signal S1 from the control device 15, and outputs the amplified carrier signal Sf to the transmitting antenna body 13A. For example, the output permission signal S1 is permitted to be transmitted at a high level and is not permitted to be transmitted at a low level. The amplified carrier wave signal (question signal) Sf is radiated from the transmitting antenna body 13A toward the tag 10.

  On the other hand, the tag 10 receives a carrier signal (interrogation signal) Sf of 2.45 GHz. At this time, the interrogation signal transmitted from the tag reader 20 is reflected from the surrounding objects and the tag 10 and returned. The signal reflected from other than the tag is a carrier signal Au (here, a single carrier signal) whose phase is shifted as shown in FIG. 3A compared to the carrier signal Sf transmitted from the tag reader 20. is there.

  That is, when the carrier wave signal (question signal) Sf radiated toward the tag 10 is reflected by an object other than the tag, the carrier wave at the time of reception is compared with the carrier wave signal Sf at the time of transmission as shown in FIG. 5B. The phase of the signal Au is shifted and the amplitude is attenuated to, for example, “2”. In FIG. 5B, θu indicates a phase shift (phase difference). The phase difference θu is a difference between the phase of the carrier signal Sf radiated from the transmission unit 12 and the phase of the carrier signal Au reflected from the object.

  In the tag 10, in the power supply unit 5 connected to the antenna body 1A, the induced power based on the carrier signal Sf received by the antenna body 1A is supplied to the amplitude modulation unit 2, the memory unit 3, and the clock oscillator 4. The In the memory unit 3, data (code data or the like; DATA) unique to the identified object shown in FIG. 6A is read based on a clock signal (CLK) having a predetermined frequency, and the data is output to the amplitude modulation unit 2. The clock signal is oscillated by the clock oscillator 4 and output to the memory unit 3. Thus, the system 100 is configured such that the tag 10 does not need to be provided with a battery or the like.

  In the amplitude modulation unit 2, for example, the carrier wave signal Sf is amplitude-modulated with the specific data read from the memory unit 3, and the tag amplitude modulation signal (response signal) Sf after amplitude modulation as shown in FIG. 6B is performed. (D) is transmitted. The response signal Sf (D) is scattered (transmitted) through the antenna body 1B. In this example, a BPSK (Binary Phase Shift Keying) modulation unit may be provided instead of the amplitude modulation unit 2.

  The response signal Sf (D) scattered (transmitted) from the antenna body 1B is received by the antenna 13B of the tag reader 20. At this time, the carrier combined signal Sf ′ including the carrier signal Au reflected from the object is also received through the antenna body 13B as the response combined signal Sin together with the response signal Sf (D) as shown in FIG. 6C.

  The phase synchronization detector 31 connected to the antenna 13B tracks the phase of the response composite signal Sin including the carrier composite signal Sf ′ and the response signal Sf (D), and transmits the carrier signal Sf during transmission shown in FIG. 3C. And the phase difference θr between the received carrier wave composite signal Sf ′ and the received carrier wave signal Sf ′. At this time, the phase detection circuit 41 refers (cheats) the frequency component of the carrier signal Sf from the oscillator 11 and compares the phase of the response composite signal Sin at the time of reception with the phase of the carrier signal Sf from the oscillator 11. . As a result of this comparison, the phase difference θr of the carrier combined signal Sf ′ shown in FIG. 3C is detected.

  The phase difference θr of the carrier wave synthesis signal Sf ′ is output to the phase difference comparison circuit 42. The phase difference comparison circuit 42 compares the phase difference estimated value θr ′ output from the phase difference output circuit 44 with the phase difference θr output from the phase detection circuit 41, and does not synchronize with the carrier signal Sf at the time of transmission. A synchronization detection signal (DC component) Sd for locking to the composite signal Sf ′ is output.

  The synchronization detection signal Sd is output to the LPF circuit 43. The LPF circuit 43 filters the synchronization detection signal Sd and outputs a phase difference estimation voltage Vd. The phase difference estimation voltage Vd is a DC voltage for estimating the phase difference θr of the carrier combined signal Sf ′ that is not synchronized with the carrier signal Sf at the time of transmission. The phase difference estimation voltage Vd is output from the LPF circuit 43 to the phase difference output circuit 44. The phase difference output circuit 44 outputs a phase difference estimated value θr ′ based on the phase difference estimated voltage Vd to the phase difference comparing circuit 42 and the amplitude control unit 32.

  As described above, the phase synchronization detection unit 31 detects and compares the phase difference θr between the carrier signal Sf at the time of transmission and the carrier signal Sf ′ at the time of reception, and estimates the phase difference θr by the primary loop. The phase difference estimated value θr ′ is output to the phase difference comparison circuit 53 and the amplitude adjustment circuit 55 of the amplitude control unit 32.

  In addition, the amplitude control unit 32 tracks the amplitude of the carrier combined signal Sf ′ in which the carrier signal Au reflected from the surrounding object and the carrier component Ad of the response signal Sf (D) from the tag 10 are combined. It is made like. For example, the arithmetic circuit 51 operates to subtract (subtract) the carrier combined signal Sf ′ phase-controlled by the phase control circuit 56 from the response combined signal Sin at the time of reception. In this example, a signal obtained by subtracting the carrier combined signal Sf ′ from the response combined signal Sin is the response signal Sf (D) of the tag 10 and includes a data modulation component.

  In order to obtain such a response signal Sf (D) of the tag 10, the arithmetic circuit 51 sends the response signal Sf (D) to the phase detection circuit 52 from the carrier signal Sf at the time of transmission and the response composite signal Sin at the time of reception. The carrier wave synthesis signal Sf ′ until is extracted. The phase detection circuit 52 inputs the carrier signal Sf at the time of transmission and the carrier signal Sf ′ until the response signal Sf (D) is extracted from the response composite signal Sin at the time of reception to obtain the carrier signal Sf ′. The phase difference θr with respect to the carrier signal Sf at the time of transmission is detected. For example, in the phase detection circuit 52, the frequency component of the carrier wave signal Sf is referred (cheated) from the oscillator 11 in the same manner as the phase synchronization detection unit 31, and the phase of the carrier wave synthesis signal Sf ′ of the response synthesized signal Sin at the time of reception, The phase of the carrier signal Sf from the oscillator 11 is compared. From the comparison result, the phase difference θr shown in FIG. 3C is detected.

The phase difference θr is output from the phase detection circuit 52 to the phase difference comparison circuit 53. The phase difference comparison circuit 53 receives the phase difference estimation value θr ′ from the phase difference output circuit 44 and the phase difference θr of the carrier combined signal Sf ′ at the time of reception output from the phase detection circuit 52, and receives the phase difference. The estimated value θr ′ is compared with the phase difference θr of the carrier combined signal Sf ′.
Based on the comparison result, the phase difference comparison circuit 53 outputs to the LPF circuit 54 an amplitude adjustment signal (DC component) Sa for controlling the amplitude locked to the carrier wave composite signal Sf ′ at the time of reception.

  The LPF circuit 54 filters the amplitude adjustment signal Sa output from the phase difference comparison circuit 53 and outputs an amplitude estimated value Va. The amplitude estimation value Va is a DC voltage for estimating the amplitude value of the carrier combined signal Sf ′ that is not synchronized with the phase of the carrier signal Sf at the time of transmission.

  The amplitude estimation value Va is output from the LPF circuit 54 to the amplitude adjustment circuit 55. The amplitude adjustment circuit 55 receives the amplitude estimation value Va output from the LPF circuit 54 and the phase difference estimation value θr ′ output from the phase difference output circuit 44, and receives the phase difference of the carrier combined signal Sf ′ at the time of reception. The amplitude is adjusted corresponding to the estimated value θr ′, and the amplitude component Ax and the phase difference component θx after amplitude adjustment are output. The amplitude component Ax and the phase difference component θx are for removing the carrier combined signal Sf ′ from the response combined signal Sin.

  The amplitude component Ax and the phase difference component θx are output from the amplitude adjustment circuit 55 to the phase control circuit 56. The phase control circuit 56 receives the carrier wave signal Sf at the time of transmission from the oscillator 11, and receives the phase difference component θx and the amplitude component Ax for removing the carrier wave synthesis signal Sf ′ from the amplitude adjustment circuit 55. The phase control circuit 56 controls the phase and amplitude of the carrier signal Sf output from the oscillator 11 on the basis of the phase difference component θx and the amplitude component Ax output from the amplitude adjustment circuit 55, and generates the carrier combined signal Sf ′. create. The carrier combined signal Sf ′ created by this phase and amplitude control is output from the phase control circuit 56 to the arithmetic circuit 51.

  This carrier combined signal Sf ′ includes the carrier signal Au reflected from the surrounding object at the time of reception shown in FIG. 3A and the carrier component Ad included in the response signal Sf (D) shown in FIG. 3B. It is a signal whose phase is shifted from the carrier wave signal Sf at the time of transmission. In this example, when the phase difference estimated value θr ′ and the phase difference θr of the carrier combined signal Sf ′ become equal, the carrier combined signal Sf ′ can be removed from the response combined signal Sin at the time of reception.

  At the time of such reception, the response signal Sf (D) obtained by removing the carrier combined signal Sf ′ from the response combined signal Sin is output to the demodulation circuit 40. The demodulation circuit 40 demodulates the response signal Sf (D) based on the carrier signal Sf and outputs tag-specific data (DATA). The data is read by the data reading unit 50 and displayed on the monitor 16 through the control device 15. The monitor 16 displays the price, name, etc. based on the unique data of the identified object 9 read from the tag 10.

  As described above, according to the tag reader system 100 as the embodiment of the present invention, when the predetermined data is wirelessly communicated by the backscatter communication method, the amplitude reader 32 of the receiver 14 performs the tag reader 20. Is reproduced based on the phase difference component θx and the amplitude component Ax of the carrier combined signal Sf ′, and the reproduced carrier combined signal Sf ′ at the time of reception is reproduced here. In reverse phase, this is added to the response composite signal (amplitude modulation signal of the tag 10) Sin.

  Accordingly, the carrier combined signal Sf ′ including the carrier signal Au reflected from the surrounding object can be removed from the response combined signal Sin at the time of reception, and the response signal (tag amplitude modulation signal) Sf (D) from the tag 10 can be removed. Can only get. Thereby, the data modulation component included in the response signal Sf (D) returned from the tag 10 can be compensated, and the S / N ratio of the response signal Sf (D) can be improved. In addition, highly reliable data that is not affected by interference noise can be demodulated with a relatively simple circuit configuration.

  The present invention relates to a system for reading electronic price tags attached to tableware in restaurants, merchandise, etc. in stores, a system for reading electronic tag tags attached to articles distributed on goods distribution bases, etc. The present invention is extremely suitable when applied to a guidance sign reading system for guiding.

1 is a perspective view showing a configuration example of a tag reader system 100 with a carrier wave compensation function as an embodiment according to the present invention. FIG. 2 is a block diagram showing an example of an internal configuration of a tag reader system 100. FIG. A to C are vector diagrams showing an operation example of the carrier wave signal Sf, the response signal Sf (D), and the carrier wave synthesis signal Sf ′ handled by the carrier wave compensation circuit 30. 3 is a block diagram illustrating an example of an internal configuration of a carrier wave compensation circuit 30. FIG. (A)-(C) is a figure which shows the example of a waveform of carrier wave signal Au and Ad which produced carrier wave signal Sf and the phase shift. (A)-(C) is a figure which shows the example of a waveform of the principal part in the tag reader system 100. FIG. It is a conceptual diagram which shows the structural example of the tag reader system 1 as a prior art example. 1 is a conceptual diagram illustrating a problem of a tag reader system 1. FIG.

Explanation of symbols

1A, 1B, 13A, 13B ... antenna body, 2 ... amplitude modulation unit, 3 ... memory unit, 4 ... clock oscillator, 5,18 ... power supply unit, 10 ... tag , 11 ... Oscillator, 12 ... Transmission unit, 14 ... Reception unit, 15 ... Control device, 16 ... Operation unit, 17 ... Monitor, 20 ... Tag reader, 30 ... Carrier wave compensation circuit, 31 ... Phase synchronization detection unit, 32 ... Amplitude control unit, 40 ... Demodulation circuit, 41, 52 ... Phase detection circuit, 42, 53 ... Phase difference comparison Circuits 43, 54... LPF circuit 44... Phase difference output circuit 50... Data reading unit 51... Operation circuit 55... Amplitude adjustment circuit 56. , 100 ... Tag reader system (wireless communication system)

Claims (5)

A transmission unit for transmitting a carrier signal of non-modulation of a predetermined frequency to the signal response of Backward scattering communication system,
A response signal obtained by modulating the carrier signal transmitted from the transmitter to the signal responder with predetermined data, and receiving and processing the response signal scattered from the signal responder; Prepared,
The signal processing unit is provided with a carrier wave compensation circuit,
The carrier compensation circuit includes:
The phase difference of the carrier signal at the time of transmission is compared with the phase of the carrier signal at the time of reception to detect phase difference information. Based on the information on the phase difference, a phase shift is detected with respect to the carrier signal at the time of transmission. A phase synchronization detector for detecting the phase difference estimate of the carrier signal at the time of reception,
An amplitude control unit that receives a phase difference estimation value of the carrier signal at the time of reception from the phase synchronization detection unit and removes the carrier signal at the time of reception that causes a phase shift with respect to the carrier signal at the time of transmission; Have
The amplitude controller is
A phase detection circuit for detecting information on the second phase difference from the difference between the phase of the carrier wave signal at the time of transmission and the phase of the carrier wave signal after compensation at the time of reception;
The second phase difference information detected by the phase detection circuit and the phase difference estimation value are compared, and an amplitude estimation value of the carrier signal at the time of reception that causes a phase shift with respect to the carrier signal at the time of transmission. A phase difference comparison circuit for detecting
The amplitude component for adjusting the amplitude of the carrier wave signal at the time of transmission and the phase for adjusting the phase from the estimated amplitude value and the phase difference estimated value of the carrier wave signal at the time of reception detected by the phase difference comparison circuit. An amplitude adjustment circuit for detecting a phase difference component;
A phase control circuit that controls the phase and amplitude of the carrier signal at the time of transmission based on the amplitude component and the phase difference component detected by the amplitude adjustment circuit ;
Information processing apparatus including an arithmetic circuit for subtracting the carrier signal at the transmission amplitude and phase is controlled by the phase control circuit from the carrier signal during the reception. Receiving a carrier signal unmodulated Jo Tokoro frequency, and the signal response of the backscatter communication method for transmitting a response signal to the carrier signal modulated by predetermined data,
An information processing device with a wireless transmission / reception function that transmits the carrier wave signal to the signal responder and receives a response signal scattered from the signal responder to perform information processing,
The information processing apparatus is provided with a carrier wave compensation circuit,
The carrier compensation circuit includes:
The phase difference of the carrier signal at the time of transmission is compared with the phase of the carrier signal at the time of reception to detect phase difference information. Based on the information on the phase difference, a phase shift is detected with respect to the carrier signal at the time of transmission. A phase synchronization detector for detecting the phase difference estimate of the carrier signal at the time of reception,
An amplitude control unit that receives a phase difference estimation value of the carrier signal at the time of reception from the phase synchronization detection unit and removes the carrier signal at the time of reception that causes a phase shift with respect to the carrier signal at the time of transmission; Have
The amplitude controller is
A phase detection circuit for detecting information on the second phase difference from the difference between the phase of the carrier wave signal at the time of transmission and the phase of the carrier wave signal after compensation at the time of reception;
The second phase difference information detected by the phase detection circuit and the phase difference estimation value are compared, and an amplitude estimation value of the carrier signal at the time of reception that causes a phase shift with respect to the carrier signal at the time of transmission. A phase difference comparison circuit for detecting
The amplitude component for adjusting the amplitude of the carrier wave signal at the time of transmission and the phase for adjusting the phase from the estimated amplitude value and the phase difference estimated value of the carrier wave signal at the time of reception detected by the phase difference comparison circuit. An amplitude adjustment circuit for detecting a phase difference component;
A phase control circuit that controls the phase and amplitude of the carrier signal at the time of transmission based on the amplitude component and the phase difference component detected by the amplitude adjustment circuit ;
Radio communications system including an arithmetic circuit for subtracting the carrier signal at the transmission amplitude and phase is controlled by the phase control circuit from the carrier signal during the reception. The wireless communication system according to 請 Motomeko 2 to use by attaching the signal response body to a predetermined identification target object. The signal responder is
An antenna body for receiving the carrier signal;
A memory unit storing the data;
An amplitude modulation unit that modulates the amplitude of the carrier signal based on data read from the memory unit;
The wireless communication system according to induced power based on the carrier signal received by the antenna body 請 Motomeko 3 that have a power supply section for supplying to said memory unit and the amplitude modulation section. A signal responder that receives an unmodulated carrier signal of a predetermined frequency, modulates the carrier signal with predetermined data and transmits a response signal is attached to the identified object, and the signal responder attached to the identified object A radio communication system of a backscatter communication system that transmits the carrier wave signal, receives a response signal returned from the signal responder, and performs signal processing .
Detecting the information of the first phase difference from the difference between the phase of the carrier wave signal at the time of transmission and the phase of the carrier wave signal at the time of reception;
Detecting a phase difference estimated value of the carrier signal at the time of reception that causes a phase shift with respect to the carrier signal at the time of transmission based on the information of the first phase difference;
Detecting the second phase difference information from the difference between the phase of the carrier signal at the time of transmission and the phase of the carrier signal after compensation;
Comparing the detected information of the second phase difference and the phase difference estimated value to detect an amplitude estimated value of the carrier signal at the time of reception that causes a phase shift with respect to the carrier signal at the time of transmission;
From the detected amplitude estimation value and phase difference estimation value of the carrier signal at the time of reception, an amplitude component for adjusting the amplitude of the carrier signal at the time of transmission and a phase difference component for adjusting the phase thereof are detected,
Control the phase and amplitude of the carrier signal at the time of transmission based on the detected amplitude component and phase difference component ,
From the carrier signal during the reception, the amplitude and radio communications for removing the carrier signal during reception caused a phase shift to the carrier signal at the time of transmission by subtracting the carrier signal at the time of transmission with controlled phase Method.

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