JP2011180799A - Device and system for remote sensing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a remote sensing device and a remote sensing system for detecting an echo signal frequency, even if the echo signal of an RFID tag (slave device) is transmitted for a short time. <P>SOLUTION: A remote sensing device 2 transmits a transmission signal St from a transmitter unit 11 for 10 μs, for example. A slave device 3 transmits an echo signal Ss, having a frequency fs, for a short time period by being excited by the transmission signal St. By means of a measuring unit 15, the remote sensing device 2 simultaneously generates comparison signals S1-Sn having different frequencies f1-fn, individually compares the frequency of the echo signal Ss with the frequencies of the comparison signals S1 to Sn, and based on the comparison result, decides the frequency range of the echo signal Ss. A controller unit 16 converts the frequency information into a corresponding temperature range, to be transmitted by a report unit 19. A remote sensing system 1 identifies the frequency of the echo signal Ss approximately 15 μs after transmitting the transmission signal St, so that the master device 2 senses the temperature sensed by the slave device 3, within a quite short time period. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a remote detection device and a remote detection system that detect the frequency of a reverberation signal transmitted by an RFID tag.

  Recently, the use of RFID (Radio Frequency Identification) system is increasing.

  In the RFID system, when a master unit (reader) transmits a signal to a slave unit (RF device) equipped with a sensor, the slave unit transmits a response signal to the master unit, and the master unit acquires a detection value of the sensor. There is something that can be done (see Patent Document 1).

JP 2007-281768 A

  There is a need to further downsize the slave unit of the RFID system and expand the range of objects to which the slave unit is attached. In response to this need, a passive slave unit has been newly developed with a simplified circuit configuration without a battery. Such a slave unit resonates when it receives a transmission signal from the master unit, and after the transmission signal from the master unit stops, transmits a damping vibration signal (hereinafter referred to as a reverberation signal) of the resonance signal. To do. After stopping the transmission signal, the master unit receives a reverberation signal (radio wave) transmitted by the slave unit for a short time (for example, about 10 μsec), and acquires the slave unit information.

  On the other hand, in the conventional RFID system, the time that the master unit can receive the response signal transmitted from the active slave unit is sufficiently longer than the time that the reverberation signal of the passive slave unit as described above can be received. It was long. Further, the base unit of the conventional RFID system is configured to receive a signal having a long reception time, such as a response signal transmitted from an active type slave unit. Therefore, when a conventional base unit of the RFID system is used, there is a problem that a reverberation signal having a short reception time transmitted by the passive type slave unit as described above cannot be received.

  Therefore, the present invention provides a remote detection device and a remote detection system that can receive a reverberation signal and acquire information of the slave unit even when the reception time of the reverberation signal transmitted by the RFID tag (slave unit) is short. For the purpose.

  The present invention relates to a remote detection device that transmits radio waves to an RFID tag by wireless communication and receives a reverberation signal transmitted by the RFID tag. The remote detection device according to the present invention includes a transmission unit, a reception unit, a comparison signal generation unit, a frequency comparison unit, and a frequency determination unit. The remote detection device transmits a transmission signal having a predetermined bandwidth including the frequency of the reverberation signal of the RFID tag to the RFID tag from the transmission unit. The RFID tag resonates when receiving this transmission signal, and transmits a reverberation signal when the transmission signal stops. The remote detection device generates a plurality of comparison signals at the comparison signal generation unit at the time of receiving the reverberation signal or before, and receives the reverberation signal at the reception unit. The frequency is compared with a frequency comparison unit. The frequency determination unit determines the frequency range of the reverberation signal based on the comparison result of the frequency comparison unit.

  The comparison of the frequency of the comparison signal and the reverberation signal can be performed as soon as the reverberation signal is received. Therefore, even if the reception time of the reverberation signal transmitted from the RFID tag is short, the frequency of the reverberation signal is compared with the frequency of any of the comparison signals. Can be determined. Therefore, the frequency range of the reverberation signal can be reliably determined regardless of the reception time of the reverberation signal.

  In the above invention, the comparison signal generator generates a plurality of comparison signals all at once. The frequency comparison unit individually compares the frequency of the reverberation signal and the frequencies of the plurality of comparison signals.

  With this configuration, the remote detection device can simultaneously compare the frequency of the reverberation signal and the frequencies of the plurality of comparison signals. Further, since the frequency of the reverberation signal and the frequencies of the plurality of comparison signals are individually compared, it is possible to complete the determination of the frequency level and the confirmation of all the determination results in a short time. Therefore, even if the reception time of the reverberation signal is short, the frequency range of the reverberation signal can be determined. Further, the frequency of the reverberation signal can be determined in a short time.

  In the above invention, the transmission unit repeatedly transmits the transmission signal, and the comparison signal generation unit generates a comparison signal having a frequency different from the previous time each time the reception unit receives the reverberation signal.

  With this configuration, even when the comparison signal generation unit can generate one to several comparison signals at a time, frequency comparison between the comparison signal and the reverberation signal having different frequencies each time is performed each time the reverberation signal is received. The frequency range of the reverberation signal can be determined based on the comparison result. Therefore, even if the reception time of the reverberation signal is short, the frequency of the reverberation signal can be reliably determined. In addition, since the number of comparison signals generated at a time may be small, the configuration of the comparison signal generation unit and the frequency comparison unit can be simplified.

  In the above invention, the frequency comparison unit includes a phase frequency comparator that outputs a pulse signal having a duty ratio corresponding to the phase difference between the comparison signal and the reverberation signal.

  The phase frequency comparator reliably compares the phase difference and frequency difference of the signals and outputs a signal corresponding to the result even if the signal is input for a short time. Therefore, by using a phase frequency comparator for the frequency comparison unit, the frequency range of the reverberation signal can be reliably determined even if the reception time of the reverberation signal is short.

  In the above invention, the remote detection device further includes a comparison signal setting unit. The comparison signal setting unit sets the frequencies of the plurality of comparison signals.

  With this configuration, when reverberation signals are received from a plurality of RFID tags having different reverberation signal frequencies, the band of the plurality of comparison signals is changed according to the RFID tag, so that the reverberation signal of each RFID tag can be changed. It is possible to determine in which frequency range the frequency falls. Further, when receiving a reverberation signal from a certain RFID tag, it is determined which frequency range of the frequency range of the reverberation signal is roughly determined, and based on the result, a plurality of comparison signal generation units are provided with By narrowing the frequency band and frequency interval of the comparison signal, the frequency range of the reverberation signal can be determined with high accuracy.

  In the above invention, the remote detection device further includes a frequency conversion unit. The frequency conversion unit converts the frequency of the reverberation signal received by the reception unit into another frequency.

  With this configuration, for example, when the frequency of the reverberation signal is a frequency that cannot be handled by the comparison signal generation unit or the frequency comparison unit, the reverberation signal is set to be converted to a frequency that can be handled by the comparison signal generation unit or the frequency comparison unit. Thus, the frequency range of the reverberation signal that can be handled by the remote detection device can be expanded.

  In the above invention, the frequency conversion unit includes a local oscillator, an oscillation frequency setting unit, and a mixer. The local oscillator has a variable oscillation frequency and outputs an output signal to the mixer. The oscillation frequency setting unit sets the oscillation frequency of the local oscillator. The mixer mixes the output signal of the local oscillator and the reverberation signal.

  According to this configuration, the mixer mixes the reverberation signal and the output signal of the local oscillator, and outputs a signal having a frequency different from that of the reverberation signal. Therefore, since the frequency of the reverberation signal can be set to an arbitrary value by the oscillation frequency setting unit, for example, when the frequency of the reverberation signal is different in a plurality of RFID tags, it is set to be converted into the same band. The frequency of the plurality of comparison signals generated by the comparison signal generator need not be changed, and the processing can be simplified.

  In the above invention, the remote detection device further includes a state determination unit. The state determination unit monitors fluctuations in the frequency of the reverberation signal determined by the frequency determination unit, and outputs the monitoring result.

  According to this configuration, the state determination unit can know whether or not the frequency determination unit can determine the frequency of the reverberation signal without being affected by the noise signal such as noise. For example, when the frequency range of the reverberation signal determined by the frequency determination unit is constant, it is not affected by the noise signal, so that the determined frequency range is set to be output. On the other hand, when the frequency range of the reverberation signal determined by the frequency determination unit varies with time, it is set to output that the frequency range cannot be determined because it is affected by the noise signal. Thereby, the reliability of frequency measurement can be improved.

  In the above invention, the remote detection device further includes a detection amount conversion unit. The detection amount conversion unit converts the frequency range determined by the frequency determination unit into a detection amount detected by the RFID tag by the sensor and outputs the detection amount.

  According to this configuration, the detection amount of the sensor corresponding to the frequency range of the reverberation signal can be grasped. Therefore, even if the reception time of the reverberation signal from the RFID tag installed at a location away from the remote detection device is short, the detection amount detected by the RFID tag by the sensor can be quickly grasped.

  The remote detection system of the present invention includes an RFID tag and any one of the remote detection devices described above. The RFID tag includes an antenna and a surface acoustic wave resonator connected to the antenna as a resonator.

  According to this configuration, the surface acoustic wave resonator can be used as a sensor because the resonance frequency changes according to the detected amount such as the ambient temperature and the pressure applied to the element. Further, the surface acoustic wave resonator can transmit a signal in a high frequency band such as several tens of MHz to several GHz via an antenna, and thus can be used as a resonator of an RFID tag. Thereby, without providing a sensor separately, the detection amount detected with the RFID tag which simplified the structure can be grasped | ascertained with the remote detection apparatus installed in the distant position. Moreover, even if the reception time of the reverberation signal from the RFID tag is short, the frequency of the reverberation signal can be reliably determined by the remote detection device.

  According to the present invention, the frequency of the reverberation signal can be determined even when the reception time of the reverberation signal transmitted by the RFID tag (child device) is short.

It is a block diagram which shows schematic structure of a remote detection system. It is a specific block diagram of an RFID tag. In a remote detection system, it is a conceptual diagram of the frequency of the signal which a remote detection apparatus and an RFID tag transmit / receive. It is a timing chart of the transmission wave and reception wave of a remote detection apparatus. It is a block diagram which shows the structure of the remote detection apparatus which concerns on 1st Embodiment of this invention. FIG. 6A is a diagram illustrating an example of the frequency of the reverberation signal and the comparison signal. FIG. 6B is a table showing an example of the output signal of each frequency comparator. FIG. 7A is a block diagram of a phase frequency comparator used in the frequency comparator. FIG. 7B is a timing chart of input / output signals of the phase frequency comparator. It is a block diagram which shows schematic structure of a remote detection system. It is a block diagram of the remote detection apparatus which concerns on 2nd Embodiment of this invention. It is a timing chart of the transmission signal and reception signal of a remote detection apparatus. FIG. 11A and FIG. 11B are diagrams illustrating examples of frequencies of the reverberation signal and the comparison signal. It is a block diagram of the remote detection apparatus which concerns on 3rd Embodiment of this invention. It is a block diagram of the remote detection apparatus which concerns on 4th Embodiment of this invention. It is a block diagram of the remote detection apparatus which concerns on 5th Embodiment of this invention. It is a flowchart for demonstrating operation | movement of the remote detection apparatus which concerns on 5th Embodiment of this invention.

[First Embodiment]
FIG. 1 is a block diagram showing a schematic configuration of a remote detection system. FIG. 2 is a specific configuration diagram of the RFID tag. FIG. 3 is a diagram illustrating frequency bands of signals transmitted and received between the remote detection device and the RFID tag in the remote detection system. FIG. 4 is a timing chart of a transmission signal and a reception signal of the remote detection device.

  The remote detection system 1 is a kind of RFID system, and includes a remote detection device (hereinafter referred to as a parent device) 2 and a passive RFID tag (hereinafter referred to as a child device) 3. The parent device 2 and the child device 3 perform wireless communication in an arbitrary band of 50 MHz to 3 GHz. In consideration of miniaturization of the handset 3 and ease of manufacture, the communication band may be set to an arbitrary band of 300 MHz to 1 GHz.

  Hereinafter, as an example of the remote detection system 1, the base unit 2 transmits a transmission signal (radio wave) St to the handset 3, and the handset 3 is excited by the transmission signal St, and the frequency according to the detection amount detected by the sensor. A configuration for transmitting the reverberation signal (radio wave) Ss of will be described.

  As shown in FIG. 1, the base unit 2 includes a transmission unit 11, an antenna duplexer 12, an antenna 13, a reception unit 14, a measurement unit 15, a control unit 16, an operation unit 17, a storage unit 18, and a notification unit 19. ing.

  The subunit | mobile_unit 3 is provided with the antenna 31 and the sensing resonator 32. FIG. As shown in FIG. 2, the sensing resonator 32 includes a piezoelectric substrate 321 made of quartz or lithium tantalate, and an IDT electrode (comb-like electrode) 322 formed on the surface of the piezoelectric substrate 321. SAW (Surface Acoustic Wave) resonator. The IDT electrode 322 is connected to an antenna (dipole antenna) 31. The sensing resonator 32 is an element that serves as both a temperature sensor and a resonator. When the transmission signal St from the parent device 2 is received by the antenna 31, the sensing resonator 32 is excited by the transmission signal St, and the measurement temperature (the temperature of the object to be measured). Resonance at a frequency fs corresponding to the ambient temperature. Further, when the transmission signal St stops, the sensing resonator 32 reverberates at a frequency fs corresponding to the measured temperature for a short time (for example, about 10 μsec) and transmits the reverberation signal Ss from the antenna 31. That is, the subunit | mobile_unit 3 is a reverberation signal of the frequency range corresponding to the temperature range which the sensing resonator 32 can measure, Comprising: The reverberation signal Ss of the frequency fs according to measured temperature is transmitted.

  Note that the response frequency (frequency of the reverberation signal) of the slave unit 3 is basically determined by the resonance frequency of the sensing resonator 32, but is specifically affected by the length of the antenna and the installation environment.

  In addition, when a pressure (atmospheric pressure, tire air pressure) or a magnetic force is applied from the outside, a compressive stress or a tensile stress is applied to the sensing resonator 32 according to the pressure or the magnetic force. Therefore, the sensing resonator 32 can also be used as an atmospheric pressure sensor, a pressure sensor, or a magnetic sensor.

  In addition, as the sensing resonator 32, a plurality of SAW resonators incorporated in one container (package) may be used. In addition, when the SAW resonator has a difference in sensitivity with respect to the measurement amount, a method of performing measurement while performing calibration (calibration) may be used. Thereby, the resonator can be realized at low cost and with high accuracy.

  In the base unit 2, the control unit 16 controls each unit. The control unit 16 outputs a control signal to the transmission unit 11 when the operation unit 17 receives a user operation or at a predetermined timing set in advance. When the control signal is input, the transmission unit 11 transmits a transmission signal (radio wave) St having a predetermined bandwidth ft (frequency ft1 to frequency ft2) as illustrated in FIG. 3 via the antenna duplexer 12 and the antenna 13. To do.

  The band ft of the transmission signal St is set so as to include the frequency range of the reverberation signal Ss of the sensing resonator 32. For example, the sensing resonator 32 has a detectable temperature range of 0 ° C. to 100 ° C., and when it is 0 ° C., the frequency of the reverberation signal Ss is fs 1, and the frequency rises in proportion to the rise in temperature. Sometimes the frequency of the reverberation signal Ss is fs2. In this case, as shown in FIG. 3, the frequency range (frequency fs1 to frequency fs2) of the reverberation signal Ss that can be output by the child device 3 is included in the band ft (frequency ft1 to frequency ft2). The bandwidth ft is set to several hundred kHz, for example.

  As illustrated in FIG. 4, the control unit 16 causes the transmission unit 11 to transmit the transmission signal St, for example, for 10 μsec. While the parent device 2 is transmitting the transmission signal St, the child device 3 resonates at the resonance frequency fs corresponding to the measured temperature (detected amount) detected by the sensing resonator 32 and transmits the resonance signal. As described above, the frequency range of the reverberation signal Ss that can be output by the child device 3 is included in the band ft of the transmission signal St of the parent device 2. Further, the signal intensity (radio wave intensity) of the reverberation signal Ss of the slave unit 3 is very weak with respect to the signal intensity (radio wave intensity) of the transmission signal St transmitted from the master unit 2. For these reasons, it is difficult to extract a resonance signal transmitted by the slave unit 3 during transmission of the transmission signal St. Therefore, in the present invention, the frequency of the reverberation signal Ss is detected.

  When the transmission signal St stops, the control unit 16 outputs a control signal to the reception unit 14 so that the reception unit 14 can receive the reverberation signal Ss via the antenna 13 and the antenna duplexer 12. Moreover, the control part 16 outputs a control signal to the measurement part 15, and makes the state which can measure the frequency of the reverberation signal Ss.

  The sensing resonator 32 of the slave unit 3 continues (reverberates) at the resonance frequency fs for a very short time even when the transmission signal St is stopped. At this time, the subunit | mobile_unit 3 transmits the reverberation signal Ss of the resonant frequency fs via the antenna 31. FIG. A sensing resonator 32 having a high Q value (for example, about Q = 10000) is used. However, since the handset 3 has only a resonator and an antenna and does not include an amplifier, the reverberation signal Ss is transmitted. The time is slight. For example, as shown in FIG. 4, the handset 3 outputs the reverberation signal Ss for about 10 μsec as an example, but the reverberation signal Ss rapidly attenuates to be equal to or less than the environmental noise. For this reason, the base unit 2 can receive the reverberation signal and measure the frequency for a short time of about 5 μsec.

  When receiving the reverberation signal Ss via the antenna 13 and the antenna duplexer 12, the reception unit 14 outputs the reverberation signal Ss to the measurement unit 15.

  The measurement unit 15 measures the frequency fs of the reverberation signal Ss and outputs the measurement result to the control unit 16. The control unit 16 corresponds to a detection amount conversion unit of the present invention, and converts the frequency fs measured by the measurement unit 15 into a corresponding temperature using a predetermined arithmetic expression or chart read from the storage unit 18. And the control part 16 makes the alerting | reporting part 19 alert | report the temperature which the subunit | mobile_unit 3 detected with an audio | voice or an image. Note that the notification unit 19 has functions of an audio output unit and a display unit.

  In addition, in the main | base station 2, it may replace with the antenna sharing device 12, and may provide an antenna switch. Moreover, you may comprise so that an antenna may be connected to each of the transmission part 11 and the receiving part 14, without providing the antenna sharing device 12 and an antenna switch.

  Next, a specific configuration of the measurement unit 15 will be described. FIG. 5 is a block diagram showing the configuration of the remote detection device according to the first embodiment of the present invention. FIG. 6A illustrates an example of the frequency of the reverberation signal and the comparison signal. FIG. 6B is a table showing an example of the output signal of each frequency comparator. FIG. 7A is a block diagram of a phase frequency comparator used in the frequency comparator. FIG. 7B is a timing chart of input / output signals of the phase frequency comparator.

  When receiving reverberation signal Ss, base unit 2A according to the first embodiment is configured to individually compare n comparison signals S1 to Sn having different frequencies with reverberation signal Ss.

  As illustrated in FIG. 5, the measurement unit 15A includes a waveform shaping unit 21, a reference signal generation unit 22, a comparison signal generation unit 23, a frequency comparison unit 24, and a frequency determination unit 25. The comparison signal generation unit 23 includes n frequency generators 23-1 to 23-n, and the frequency comparison unit 24 includes n frequency comparators 24-1 to 24-n.

  When a control signal is input from the control unit 16 at a predetermined timing, the measurement unit 15A causes the reference signal generation unit 22 to generate a reference signal. This reference signal is input to each frequency generator 23-1 to 23-n of the measurement unit 15A. The frequency generators 23-1 to 23-n generate the comparison signals S1 to Sn of the different frequencies f1 to fn using the inputted reference signals, and the frequency comparators 24-1 to 24-n Output.

  In the frequency generators 23-1 to 23-n of the measurement unit 15A, the frequency of the comparison signal to be generated is set in advance. The frequency of the comparison signal may include the frequency range (frequency fs1 to frequency fs2) of the reverberation signal Ss that can be output by the slave unit 3. That is, f1 <fs1 <... <Fs2 <fn. Further, the comparison signals S1, S2, S3 to S (n-1), Sn generated by the frequency generators 23-1 to 23-n are f1 <f2 <f3 <... <f (n-1) <fn. The frequency interval is constant. The xth comparison signal is referred to as a comparison signal Sx. When the control signal from the control unit 16 is input, the frequency generators 23-1 to 23-n generate n comparison signals all at once.

  A frequency generator or a signal synthesizer such as PLL or DDS may be used as the frequency generator. Since the frequency output from the frequency generator is predetermined and the signal may always be generated, the comparison signal can be stably output even when the reception time of the reverberation signal Ss is short. When a PLL is used as the frequency generator, a plurality of comparison signals can be generated at fine frequency intervals such as 1 kHz steps. For example, the frequency of the comparison signal may be set as 100.001 MHz, 100.002 MHz, 100.003 MHz, or the like.

  Since the reception time of the reverberation signal Ss is as short as about 5 μs, the comparison signal generation unit 23 transmits the transmission signal St so that the frequency comparison unit 24 can immediately compare the frequencies when the reverberation signal Ss is received. It is preferable to set so that a comparison signal is generated and output to the frequency comparison unit 24 before the signal is output.

  When the reverberation signal Ss is input from the reception unit 14, the waveform shaping unit 21 shapes the waveform of the reverberation signal Ss and outputs a signal having an amplitude suitable for the operation of the frequency comparator. When the frequency comparison unit 24 is configured by a digital circuit, the waveform shaping unit 21 converts the reverberation signal Ss (analog signal) into a logic level signal and outputs it. The reverberation signal Ss is input to each frequency comparator 24-1 to 24-n of the frequency comparison unit 24.

  The frequency comparators 24-1 to 24-n individually compare the frequencies of the reverberation signal Ss and the comparison signals S1 to Sn, and output a signal according to the comparison result to the frequency determination unit 25. The frequency comparator 24-x outputs a signal 0 if the frequency fs of the reverberation signal Ss is less than the frequency fx of the comparison signal Sx (fs <fx), and the frequency fs of the reverberation signal Ss is the frequency of the comparison signal Sx. If fx or more (fs> fx), signal 1 is output.

  When the frequency comparator is constituted by a digital circuit, it is preferable to use a phase frequency comparator (Phase Frequency Comparator) or an exclusive-OR type phase comparator. In addition, when the frequency comparator is constituted by an analog circuit, it is preferable to use an analog multiplier or a frequency discrimination circuit.

  Further, the phase frequency comparator outputs a pulse signal having a duty ratio corresponding to the phase difference between the two input signals, and can detect not only the phase difference but also the frequency difference, so that the frequency of the reverberation signal Ss can be more reliably determined. it can. Further, it is possible to measure at a fast response speed for signals in a wide phase / frequency range. Therefore, it is particularly preferable to use a phase frequency comparator as the frequency comparator. As a phase frequency comparator, for example, TC5081AP (manufactured by Toshiba Corporation) shown in FIG. 7A is known.

  When the TC5081AP is used as the frequency comparators 24-1 to 24-n, when a comparison signal is input to the Sin (7) terminal and a reverberation signal Ss is input to the Rin (8) terminal, PDout as described above (3) Signal 0 or signal 1 is output from the terminal.

  Note that, as shown in FIG. 7B, the output of the PDout (3) terminal becomes high impedance. To prevent this, a low-pass filter (LPF) is preferably connected to the PDout (3) terminal. In order to prevent the output from becoming high impedance, a latch circuit may be connected to the PDout (3) terminal. In this case, the output is affected by a time constant peculiar when a low-pass filter is used. Absent.

  The frequency determination unit 25 determines the frequency range of the reverberation signal Ss based on the signal (signal 0 or signal 1) output from the frequency comparators 24-1 to 24-n. The frequency determination unit 25 checks which comparison signal frequency the reverberation signal Ss has. That is, the signals output from the frequency comparators 24-1 to 24-n are confirmed, and the frequency comparator 24-x having the maximum frequency of the comparison signal among the frequency comparators that output the signal 0; Among the frequency comparators that output 1, the frequency comparator 24-(x + 1) having the smallest frequency of the comparison signal is selected. Then, the frequency range of the reverberation signal Ss is determined by confirming the frequency of the comparison signal input to these two frequency comparators.

  For example, as shown in FIG. 6A, when the frequency of the reverberation signal Ss is between the frequency f2 of the comparison signal S2 and the frequency f3 of the comparison signal S3, the frequency comparators 24-1 to 24-1. 24-n outputs the signal shown in FIG. That is, the frequency comparator 24-1 and the frequency comparator 24-2 output the signal 0, and the frequency comparator 24-3 to the frequency comparator 24-n output the signal 1. In this case, the frequency comparator 24-2 has the highest frequency of the comparison signal among the frequency comparators that output the signal 0, and the frequency of the input comparison signal S2 is f2. Of the frequency comparators that output the signal 1, the frequency of the comparison signal is the lowest in the frequency comparator 24-3, and the frequency of the input comparison signal S3 is f3. Therefore, the frequency determination unit 25 determines that the frequency (range) fs of the reverberation signal Ss is the frequency f2 to the frequency f3.

  The frequency determination unit 25 outputs information that the frequency fs of the reverberation signal Ss is between the frequency f2 and the frequency f3 to the control unit 16.

  As described above, the control unit 16 converts the frequency information into the corresponding temperature range, and causes the notification unit 19 to notify the temperature range detected by the slave unit.

  As described above, in the case of the example shown in FIG. 4, in the remote detection system 1, the frequency of the reverberation signal Ss is known about 15 μs after the transmission signal St is transmitted. The detected temperature can be detected in a very short time.

  As described above, in the remote detection device of the present invention, the time required for the PLL feedback loop to converge is not required unlike the conventional configuration, and the frequency is measured like the reverberation signal transmitted by the slave unit 3. The frequency (frequency range) of the reverberation signal can be determined instantaneously (within several tens of cycles) for a short time signal such as about 5 μsec. In addition, the remote detection device 2 can determine the frequency in a short time with a resolution corresponding to a plurality of frequencies generated by the comparison signal generation unit 23 and the number of phase comparators of the frequency comparison unit 24.

  In the case where all the frequency comparators and frequency generators are formed using digital logic circuits, the remote detection device can be realized in a small size, light weight, and low cost by using a PLD (Programmable Logic Device).

  A frequency discriminator can also be used as the frequency comparator. The frequency discriminator is a kind of fV converter that operates in a radio frequency band (several MHz to several hundred MHz), and in a certain band, the output voltage is proportional to the input frequency, so the frequency is easy. Can be determined.

[Second Embodiment]
Next, the configuration of the remote detection device (master device) according to the second embodiment of the present invention will be described. FIG. 8 is a block diagram showing a schematic configuration of the remote detection system. FIG. 9 is a block diagram of a remote sensing device according to the second embodiment of the present invention. FIG. 10 is a timing chart of a transmission signal and a reception signal of the remote detection device, and FIGS. 11A and 11B are diagrams illustrating examples of frequencies of a reverberation signal and a comparison signal.

  The base unit 2B according to the second embodiment is configured so that the frequency fx of the comparison signal Sx generated by the comparison signal generation unit 23 can be changed.

  The base unit 2B shown in FIG. 9 has a comparison signal setting unit 26 added to the measurement unit 15A of the base unit 2A shown in FIG. The comparison signal setting unit 26 sets (changes) the frequencies of the comparison signals S1 to Sn to be generated by the frequency generators 23-1 to 23-n. The frequency generators 23-1 to 23-n are programmable frequency dividers, programmable PLLs, DDSs, or the like so that the comparison signal setting unit 26 can change the frequencies of the comparison signals S1 to Sn. The signal synthesizer is used. The other parts have the same configuration as the base unit 2A. In the following description, differences will be described.

  Since the measurement unit 15B can change the frequencies (bands) of the plurality of comparison signals S1 to Sn generated by the comparison signal generation unit 23 by using the comparison signal setting unit 26, the frequency measurement in an arbitrary band is possible. . For example, when the remote detection system 1 includes the parent device 2B and the plurality of child devices 3-1 to 3-n, the bands of the reverberation signals Ss of the child devices are set to different values without overlapping each other. And the detection amount of the subunit | mobile_unit 3-1 to 3-n is acquired in a short time by transmitting in order, switching the transmission signal St1-Stn including the zone | band of the reverberation signal Ss of each subunit | mobile_unit from the main | base station 2B. it can.

  Next, an example of the operation of base unit 2B will be described. A remote detection system 1B shown in FIG. 8 is configured to include a parent device 2B, a child device 3A, and a child device 3B. As shown in FIG. 11A, the range in which the frequency of the reverberation signal Ss1 of the handset 3A changes is the band fa (frequency f11 to frequency f1n), and the range in which the frequency of the reverberation signal Ss2 of the handset 3B changes is the band fb. (Frequency f21 to frequency f2n). The band fa and the band fb do not overlap. Assume that handset 3A is attached to article A and handset 3B is attached to article B. The bandwidth of fa and fb is set to 100 kHz to several hundred kHz, and the interval between the center frequency of fa and the center frequency of fb is preferably set to 1 MHz to several MHz. For example, the band fa is the 101 MHz band, and the band fb is A band such as the 102 MHz band is set.

  As shown in FIG. 10, first, base unit 2B transmits transmission signal St1 of band fa for 10 μs, and continues a state in which a reverberation signal from mobile unit 3A can be received for 10 μs. Subsequently, the transmission signal St2 in the band fb is transmitted for 10 μsec, and the state in which the reverberation signal from the handset 3B can be received is continued for 10 μsec.

  The subunit | mobile_unit 3A will transmit the reverberation signal Ss1 of the frequency fs1 according to the temperature of the article | item A, if excited by the transmission signal St1 and the transmission signal St1 stops.

  When the transmission unit 11 stops the output of the transmission signal St1, the control unit 16 of the parent device 2B outputs a control signal to the comparison signal setting unit 26. When the control signal is input, the comparison signal setting unit 26 outputs signals that cause the frequency generators 23-1 to 23-n to generate the comparison signals S11 to S1n having the frequencies f11 to f1n, respectively. The frequency generators 23-1 to 23-n generate and output comparison signals S11 to S1n having frequencies set by the comparison signal setting unit 26. The frequency comparison unit 24 outputs a signal corresponding to the comparison result, and the frequency determination unit 25 determines that the frequency fs1 of the reverberation signal Ss1 is between the frequency f12 and the frequency f13, and sends the determination result to the control unit 16. Output.

  Further, when the control unit 16 of the base unit 2B stops the transmission unit 11 from outputting the transmission signal St2, the control unit 16 generates the comparison signals S21 to S2n of the frequency f21 to the frequency f2n and performs the same process as the above process. Thus, it is determined that the frequency fs2 of the reverberation signal Ss2 from the handset 3B is between the frequency f23 and the frequency f24.

  And the control part 16 converts said each frequency into corresponding temperature, and makes the alerting | reporting part 19 alert | report the temperature detected with the subunit | mobile_unit 3A and the subunit | mobile_unit 3B by an audio | voice or a display.

  As described above, the remote detection device according to the second embodiment can continuously measure the detection amounts of a plurality of slave units in a short time.

  Next, in the above configuration, each time the reverberation signal Ss is compared with the plurality of comparison signals, the bandwidth and frequency interval of the plurality of comparison signals generated by the comparison signal generation unit 23 are narrowed (narrowed). Thus, the frequency of the reverberation signal Ss can be measured with high accuracy.

  For example, as described based on FIG. 11A, when it is determined that the frequency fs1 of the reverberation signal Ss1 is between the frequency f12 and the frequency f13, the comparison signal setting unit 26 outputs the following signal: To do. That is, as shown in FIG. 11B, when the control signal from the control unit 16 is input, the comparison signal setting unit 26 performs comparison signals S12, S122, which are obtained by dividing the frequency f12 to the frequency f13 into n equal parts. Signals that cause S12 (n-1) and S13 to be generated by the frequency generators 23-1 to 23-n are output. In this case, base unit 2 determines that frequency fs1 of reverberation signal Ss1 is between frequency f124 and frequency f125.

  By repeating such processing, high-accuracy measurement can be performed by a small circuit with originally low measurement accuracy.

  In the above description, the frequency of the comparison signal generated by the comparison signal generation unit 23 is changed according to the slave that transmits the transmission signal. However, the present invention is not limited to this, and the frequency of the comparison signal is set. It is also possible to set a band to be included so as to include a band of a reverberation signal transmitted by a plurality of slave units. For example, in the configuration shown in FIG. 11A, the comparison signal includes the band fa and the band fb, that is, each frequency obtained by dividing f11 to f2n into n equal parts can be used as the frequency of the comparison signal. is there. In this case, as shown in FIGS. 11A and 11B, it is preferable to perform measurement a plurality of times and to narrow the bandwidth and frequency interval of the comparison signal every time it is measured. Thereby, the accuracy of the frequency of the reverberation signal Ss can be increased.

  The control unit 16 may directly set the frequency of the comparison signal with respect to the frequency generators 23-1 to 23-n without providing the comparison signal setting unit 26.

[Third Embodiment]
Next, a remote detection device (master) according to a third embodiment of the present invention will be described. FIG. 12 is a block diagram of a remote sensing device according to the third embodiment of the present invention.

  The base unit 2C according to the third embodiment is configured to convert the frequency of the reverberation signal Ss into another frequency and output it to the measurement unit.

  In the master unit 2C shown in FIG. 12, the configuration of the receiving unit 14B of the master unit 2B shown in FIG. 5 is changed. The other parts have the same configuration as the base unit 2B. In the following description, differences will be described.

  The receiving unit 14C includes an oscillation frequency setting unit 141, a local oscillator 142, and a mixer 143.

  The oscillation frequency setting unit 141 sets the local oscillation frequency fk output from the local oscillator 142 to an arbitrary value.

  The local oscillator 142 generates a signal having the local oscillation frequency fk set by the oscillation frequency setting unit 141 using the reference signal output from the reference signal generation unit 22 and outputs the signal to the mixer 143.

  The mixer 143 converts the reverberation signal Ss of the (reception) frequency fs output from the antenna duplexer 12 into the signal of the intermediate frequency fss using the signal of the local oscillation frequency fk output from the local oscillator 142. And output to the waveform shaping unit 21. Intermediate frequency fss = fs−fk.

  For example, the mixer 143 converts the frequency to 10 MHz to 100 MHz and performs comparison. This is because a comparator that compares frequencies of about 1 GHz at high speed is not very common. When the frequency (reception frequency) fss of the reverberation signal is 1.1 GHz, when the local oscillation frequency fk is 1.0 GHz, the intermediate frequency fss is 100 MHz.

  By configuring the master unit 2 in such a configuration, the frequency of the reverberation signal Ss is outside the frequency range (band) of the comparison signal generated by the frequency comparison unit 24 or outside the frequency band in which the frequency comparison unit 24 can operate. Even so, the frequency of the reverberation signal can be converted within the frequency range of the comparison signal generated by the frequency comparison unit 24 by frequency conversion or within the frequency band in which the frequency comparison unit 24 can operate. Thereby, the band (frequency range) that can be measured by the master unit 2C can be expanded.

  In addition, as described in the second embodiment, the comparison signal setting unit 26 can generate the comparison signal generated in the comparison signal generation unit 23 a plurality of times every predetermined time while narrowing down the band of the comparison signal. The combination of the comparison signal setting unit 26 and the receiving unit 14C enables highly accurate measurement even if the band of the reverberation signal Ss is wide.

  Further, the oscillation frequency setting unit 141 is configured to arbitrarily set the frequency of the local oscillator 142 and perform frequency conversion, thereby enabling measurement in an arbitrary frequency band.

  Note that the local oscillation frequency value of the local oscillator 142 may be a fixed value without providing the oscillation frequency setting unit 141. Even with this configuration, the above-described effect can be obtained.

  Further, the control unit 16 may directly set the local oscillation frequency value in the local oscillator 142 without providing the oscillation frequency setting unit 141.

  In base unit 2C, the frequency of the comparison signal generated by frequency generators 23-1 to 23-n can be set in advance without providing comparison signal setting unit 26.

[Fourth Embodiment]
Next, a remote detection device (master) according to a fourth embodiment of the present invention will be described. FIG. 13 is a block diagram of a remote sensing device according to the fourth embodiment of the present invention.

  Base unit 2D according to the fourth embodiment is configured to be able to determine whether or not it is affected by a noise signal when measuring a frequency.

  In the base unit 2D shown in FIG. 13, a state determination unit 27 is added to the measurement unit 15B of the base unit 2C shown in FIG. In addition, the state determination unit 27 outputs the frequency measurement result to the control unit 16 instead of the frequency determination unit 25. The other parts have the same configuration as the base unit 2C shown in FIG. In the following description, differences will be described.

  The state determination unit 27 monitors whether the output of the frequency determination unit 25 is stable or fluctuates as time passes, and is the reverberation signal Ss transmitted by the slave unit 3 or It is determined (monitored) whether it is a noise signal such as noise generated from surrounding devices, and a determination result (monitoring result) is output to the control unit 16. A noise signal is a signal whose frequency frequently fluctuates with time.

  The state determination unit 27 measures the reverberation signal Ss when the frequency value determined by the frequency determination unit 25 is always the same in 5 μsec, which is the reception time during which the frequency of the reverberation signal Ss can be determined. And the frequency value is output to the control unit 16. On the other hand, when the value of the frequency determined by the frequency determination unit 25 constantly changes, it is determined that the noise signal is measured instead of the reverberation signal Ss, and the frequency of the reverberation signal Ss cannot be measured due to the influence of the noise signal. To the control unit 16. The control unit 16 causes the notification unit 19 (not shown) to notify that the frequency range or frequency cannot be measured according to the input signal (information).

  Therefore, since it is possible to determine which of the reverberation signal and the noise signal is being measured, high reliability can be achieved.

  Note that each frequency comparator of the frequency comparison unit 24 can determine the frequency for each period of the reverberation signal Ss. When the frequency of the reverberation signal Ss is 100 MHz, since one cycle is 0.01 μsec, the master unit 2D can determine the frequency up to 500 times in 5 μsec.

  Since the frequency comparison unit 24 can determine the frequency a plurality of times in a short time, most of the frequency determination results are the same. It is also possible to determine that it has been determined. In this case, if the number of different values is about how many times the frequency of the reverberation signal Ss can be measured without being affected by the noise signal, it is determined through experiments or the like. good.

  Of course, the state determination unit can also be provided in the parent device 2A shown in FIG. 5 and the parent device 2B shown in FIG.

[Fifth Embodiment]
Next, a remote detection device (master) according to a fifth embodiment of the present invention will be described. FIG. 14 is a block diagram of a remote sensing device according to the fifth embodiment of the present invention.

  The base unit 2E according to the fifth embodiment is configured to compare the frequency of the reverberation signal Ss with one comparison signal. Base unit 2E transmits a transmission signal in the same band at a predetermined cycle to handset 3 (not shown), changes the frequency of the comparison signal every time it receives reverberation signal Ss, and compares the frequency different from the previous time. The frequencies of the signal for use and the reverberation signal Ss are compared. The frequency of the reverberation signal Ss is determined by repeating this n times.

  In the base unit 2E shown in FIG. 14, the configurations of the comparison signal generation unit 23 and the frequency comparison unit 24 are changed in the measurement unit 15A of the base unit 2A shown in FIG. Further, the operations of the frequency determination unit 25 and the comparison signal setting unit 26 are different. The other parts have the same configuration as the base unit 2A. In the following description, differences will be described.

  The comparison signal generation unit 23E includes one frequency generator 23-1, and the frequency comparison unit 24 includes one frequency comparator 24-1. The comparison signal setting unit 26 causes the frequency generator 23-1 to generate comparison signals having different frequencies each time. The frequency determination unit 25E outputs the determination result output from the frequency comparator 24-1 to the control unit 16. The base unit 2E may be configured to directly input the output of the frequency comparator 24-1 to the control unit 16 without providing the frequency determination unit 25E.

  Master unit (remote detection device) 2E operates as follows. As an example, a case where the frequency fs of the reverberation signal Ss is between f2 and f3 as shown in FIG. FIG. 15 is a flowchart for explaining the operation of the remote sensing device according to the fifth embodiment of the present invention. In the following description, the control unit 16 incorporates the counter h.

  The user operates the operation unit 17 of the parent device 2E in order to know the temperature of the article to which the child device 3 is attached. When detecting the operation of the operation unit 17 (S1), the control unit 16 resets the value of the counter h to h = 1 (S2). Then, the transmitter 11 transmits the transmission signal St for a certain time (for example, 10 μsec) (S3). When the transmission of the transmission signal St is completed, the receiver 14 receives the reverberation signal Ss, and the measurement unit 15E starts measurement. (S4).

  The comparison signal setting unit 26E of the measurement unit 15E checks the counter h (S5), and generates a comparison signal having a frequency corresponding to the counter value (S6). For example, when the counter is h = 1, the frequency generator 23-1 is caused to generate the comparison signal S1 having the frequency f1. When h = x, the frequency generator 23-1 is caused to generate a comparison signal Sx having the frequency fx.

  The frequency comparator 24-1 compares the reverberation signal Ss and the frequency of the comparison signal S1 (S7), and outputs a signal corresponding to the comparison result (S8). When the comparison signal is S1, since the reverberation signal Ss has a higher frequency, the signal 0 is output. On the other hand, when the comparison signal is S3, since the reverberation signal Ss has a lower frequency, the signal 1 is output. The frequency determination unit 25 outputs the determination result to the control unit 16.

  When the determination result is input, the control unit 16 stores the number of counters h in association with the determination result (S9). If the counter h is not n = S (S10), the control unit 16 increments the number of the counters h by 1 (S11), and repeats the processing from step S3 to step S11 until the counter h = n.

  In step S10, if the counter h = n, the control unit 16 confirms the number of counters h of the signal 0 input last and the number of counters h of the signal 1 input first. Further, the information on the initial value and frequency interval of the comparison signal set in the comparison signal setting unit 26E is confirmed (S12). Based on these pieces of information, the frequency range of the reverberation signal Ss is determined (S13). The control unit 16 causes the notification unit 19 (not shown) to notify the determined frequency range of the reverberation signal Ss (S14).

  With such a configuration, even if the reception time of the reverberation signal of the slave unit is short, the master unit can acquire the detection amount of the sensor by repeatedly transmitting the reverberation signal Ss.

  In the above process, it is determined in step S10 whether or not the counter h = n. However, another process can be performed. For example, if the output of the frequency comparator 24-1 is 1, that is, if the frequency of the comparison signal is lower than that of the reverberation signal Ss, the setting in step S12 may be performed. By setting in this way, the frequency range can often be determined without performing the frequency comparison n times, so that the processing time can be shortened.

[Other Embodiments]
In the description of the fifth embodiment, the configuration in which the base unit 2E includes one frequency generator 23-1 and one frequency comparator 24-1 has been described. However, as illustrated in FIG. It is also possible to employ a configuration including n comparators. Also in this configuration, it is preferable to generate comparison signals having different frequencies at regular intervals. For example, n frequency generators generate comparison signals f1 to fn at the first time, f (n + 1) to f (2n) comparison signals at the second time, and mth time. By generating comparison signals f (m + 1) to f (mn), it is possible to compare mn comparison signals with the reverberation signal Ss.

  At this time, the frequency determination unit 25 confirms the signals output from the frequency comparators 24-1 to 24-n, and the number of the two adjacent frequency comparators at the point where the signal switches from 0 to 1, and what The information indicating whether switching has been performed for the second time is output to the control unit 16. That is, information specifying the frequency comparator 24-x having the maximum frequency of the comparison signal among the frequency comparators that output the signal 0, and the frequency of the comparison signal having the minimum frequency among the frequency comparators that output the signal 1 Information identifying the frequency comparator 24- (x + 1) and information indicating the number of times of detection are output to the control unit 16.

  The control unit 16 checks the frequency fs (frequency range) of the reverberation signal Ss by checking the frequency of the comparison signal output by the frequency comparator 24-x and the frequency comparator 24- (x + 1) at the xth time. judge.

  With this configuration, mn comparison signals having different frequencies can be generated, so that the frequency can be determined in a short time even when the band of the reverberation signal Ss is wide. When the band of the reverberation signal Ss is narrow, the frequency of the reverberation signal Ss can be determined with high accuracy in a short time by narrowing the frequency interval of the comparison signal.

  Further, in the base unit 2E shown in FIG. 14, as in the third embodiment, a configuration for converting the frequency of the reverberation signal Ss (local oscillator 142 and mixer 143) and a configuration for converting the conversion frequency to an arbitrary value ( An oscillation frequency setting unit 141) can be provided. Thereby, the frequency range (band) which can be measured can be expanded like 3rd Embodiment.

  In addition, the base unit 2E shown in FIG. 14 can be provided with a state determination unit as in the fourth embodiment. Thereby, when the master unit measures the reverberation signal Ss, it can be determined whether or not it is affected by the noise signal.

  In the description of the first to fifth embodiments, the configuration in which the slave unit includes the sensing resonator 32 has been described. However, the configuration is not limited to this, and the slave unit resonates and reverberates at the determination frequency. The structure provided with the vessel may be sufficient. In this case, for example, as described in the second embodiment, a plurality of slave units are prepared, and the frequency of the reverberation signal Ss of each slave unit is set at a predetermined interval. In addition, each handset is attached to an article that is normally carried. By comprising in this way, detection and management of articles | goods can be performed, for example, confirmation of a forgotten thing can be performed.

1, 1B: Remote detection system 2, 2A, 2B, 2C, 2D, 2E ... Remote detection device (base unit)
3, 3A, 3B ... RFID tag (child device)
14, 14B, 14C ... receiving units 15, 15A, 15B, 15C, 15E ... measuring unit 16 ... control unit 22 ... reference signal generating unit 23, 23E ... comparison signal generating units 23-1 to 23-n ... frequency generators 24... Frequency comparison units 24-1 to 24-n... Frequency comparators 25 and 25 E. Frequency determination units 26 and 26 E... Frequency setting unit 27... State determination unit 32. 143 ... Frequency converter

Claims (10)

A remote detection device that transmits radio waves to an RFID tag and receives a reverberation signal transmitted by the RFID tag,
A transmission unit for transmitting a transmission signal having a predetermined frequency bandwidth including the frequency of the reverberation signal;
A receiver for receiving the reverberation signal;
A signal generator for comparison, which is a signal in a frequency band including the frequency of the reverberation signal, and generates a plurality of comparison signals having different frequencies.
A frequency comparison unit that compares the frequency of the reverberation signal with the frequencies of the plurality of comparison signals and outputs a comparison result;
A frequency determination unit that determines a frequency range of the reverberation signal based on a comparison result of the frequency comparison unit;
A remote detection device comprising: The comparison signal generation unit generates the plurality of comparison signals all at once,
The remote detection device according to claim 1, wherein the frequency comparison unit individually compares the frequency of the reverberation signal and the frequencies of the plurality of comparison signals. The transmitter repeatedly transmits the transmission signal;
The remote detection device according to claim 1, wherein the comparison signal generation unit generates a comparison signal having a frequency different from the previous time each time the reception unit receives the reverberation signal.   The remote detection device according to claim 1, wherein the frequency comparison unit includes a phase frequency comparator that outputs a pulse signal having a duty ratio corresponding to a phase difference between the comparison signal and the reverberation signal. .   The remote detection device according to claim 1, further comprising a comparison signal setting unit configured to set frequencies of the plurality of comparison signals.   The remote detection device according to claim 1, wherein the reception unit includes a frequency conversion unit that converts the frequency of the received reverberation signal into another frequency.   The frequency converter includes a local oscillator having a variable oscillation frequency, an oscillation frequency setting unit that sets an oscillation frequency of the local oscillator, and a mixer that mixes the output signal of the local oscillator and the reverberation signal. The remote detection device according to claim 6.   The remote detection device according to claim 1, further comprising a state determination unit that monitors a change in frequency of a reverberation signal determined by the frequency determination unit and outputs the monitoring result.   The remote detection device according to claim 1, further comprising: a detection amount conversion unit that converts the frequency range determined by the frequency determination unit into a detection amount detected by the RFID tag by a sensor and outputs the detection amount. An RFID tag comprising an antenna and a surface acoustic wave resonator connected to the antenna as a resonator;
The remote detection device according to any one of claims 1 to 9,
Remote sensing system with

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