JP2008122255A - Distance measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a distance measuring device capable of performing distance measurement by discriminating between a signal from an object and a signal reflected from a substance other than the object. <P>SOLUTION: Fig. 1a illustrates constitution of a first transceiver 10 and Fig. 1b illustrates constitution of a second transceiver 20. The first transceiver 10 transmits two signals having different frequencies generated by a balanced modulator 106. The second transceiver 20 generates and transmits a third-order intermodulation wave from the two signals by a nonlinear device 122. The first transceiver 10 receives the third-order intermodulation wave to detect the phase difference. The distance from the first transceiver 10 to the second transceiver 20 is measured by the phase difference. Because the frequency of the signal transmitted by the first transceiver 10 is different from the frequency of the received signal (third-order intermodulation wave), it can be discriminated from the reflection wave from the substance other than the second transceiver 20, thereby preventing interference. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a distance measuring device including two transceivers and a transceiver constituting the distance measuring device.

  As a technique for transmitting a radio wave from a transceiver and receiving a reflected wave from an object and measuring the distance from the transceiver to the object by comparing the reflected wave and the transmitted wave, a method for comparing phase differences, FM- The thing by CW system etc. are known.

  Patent Document 1 discloses a technique for measuring a distance from a frequency in a locked phase by forming a PLL between a transceiver and an object.

  On the other hand, Patent Document 2 discloses a technique using an intermodulation wave generated by a diode for identification of an IC tag. There are two types of IC tags: active type with a built-in power supply and passive type without a built-in power supply. Conventionally, the reflected wave from a passive IC tag and the reflected wave from other than the IC tag cannot be distinguished. It was necessary to use a passive IC tag in an environment where there was little reflection.

Therefore, Patent Document 2 solves this problem as follows. The reader generates two signals having different frequencies using two signal generators, and transmits them to the IC tag. The IC tag that has received the two signals generates and emits an intermodulation wave by the diode. Since the reader receives an intermodulation wave having a frequency different from that of the transmission wave (two signals having different frequencies) as a reflected wave from the IC tag, it can be distinguished from a reflection from other than the IC tag.
JP2004-198306 Special table 2005-530369

  However, in Patent Document 1, since the frequencies of the transmission wave and the reception wave are the same, it cannot be distinguished from the reflection wave from other than the object, and there is a possibility that the transmission wave may be received directly. Further, when the object is difficult to reflect radio waves, or when there is an obstacle between the transceiver and the object, it is difficult to measure the distance.

  Patent Document 2 is intended for identification of IC tags and the like, and is not intended for measuring the distance between a reader and an IC tag.

  Accordingly, an object of the present invention is to realize a method and a distance measuring device that can measure a distance by discriminating a signal from an object and a signal from other than the object.

  1st invention consists of a 1st transmitter / receiver and a 2nd transmitter / receiver, The distance measuring device which measures the distance of a 1st transmitter / receiver and a 2nd transmitter / receiver WHEREIN: A 1st transmitter / receiver is low-range transmission. A data signal generator for generating a data signal, a first transmitter for generating a high frequency signal from the transmission data signal, transmitting the high frequency signal, and a return signal from the second transmitter / receiver, and receiving low-frequency data A first receiving device for converting into a signal, a distance computing device for obtaining a first distance between the first transceiver and the second transceiver based on the received data signal and the transmitted data signal obtained by the first receiving device; The second transmitter / receiver has different frequencies for the second receiving device that receives the high-frequency signal transmitted from the first transmitting device and the high-frequency signal that is output from the second receiving device due to nonlinear characteristics related to input / output. Converted to a reply signal A first nonlinear device output, a distance measuring apparatus characterized by having a.

  Here, “low frequency” means a low frequency relative to a high frequency signal, and the frequency of the transmission data signal and the frequency of the reception data may be different. Further, generating a high frequency signal from a transmission data signal means frequency conversion for obtaining a high frequency signal having a multiplied frequency of the transmission data signal, or obtaining a high frequency signal by modulating a carrier wave with the transmission data signal.

  The high frequency signal may be one signal, but may be two or more signals having different frequencies. In the case of one signal, the return signal means a harmonic, and in the case of two or more signals having different frequencies, the return signal includes not only the harmonic but also an intermodulation wave.

  When two signals are used, it is desirable that the frequency difference between the two signals is small. The two signals and the intermodulation wave can be in the same band, and the wireless standard can be easily satisfied. Further, the same antenna can be used as the transmission device or the reception device of the first and second transceivers. In addition, the transmission device and the reception device can be shared using a circulator.

  The distance calculation device is a device that detects a phase difference or a device that detects a frequency difference. When detecting the phase difference, a rectangular wave may be used as the data signal. If the data signal is an FM-CW signal, the distance can be measured by detecting the frequency difference.

  For example, a diode or a transistor can be used as the nonlinear device.

  According to a second invention, in the first invention, the first transmitter / receiver receives the high frequency signal and outputs an equivalent reply signal equivalent to the reply signal, and has the same characteristics as the first nonlinear device of the second transmitter / receiver. The second non-linear device is provided, the equivalent return signal is input to the first receiving device, and the low-frequency equivalent received data signal is output. The distance calculation device is based on the transmission data signal and the equivalent received data signal. The distance measuring device is characterized in that a correction value obtained is obtained and a value obtained by subtracting the correction value from the first distance is set as a normal distance between the first transceiver and the second transceiver.

  In a third aspect based on the first aspect, the first transmission device has a voltage controlled oscillator for generating a high frequency signal, and the distance calculation device is between the first transceiver and the second transceiver. The distance measuring device is a device that calculates a first distance based on a phase of a transmission data signal and a phase of a reception data signal when a PLL is formed and a voltage controlled oscillator is stably oscillated.

  Forming a PLL between the first transceiver and the second transceiver means that a transmission data signal or a frequency-divided signal or a multiplied signal thereof, or a received data signal or a frequency-divided signal or a frequency-multiplied signal is a reference signal. It means that it is phase-synchronized with.

  In a fourth aspect based on the second aspect, the first transmitter has a voltage controlled oscillator for generating a high-frequency signal, and the distance calculator is between the first transceiver and the second nonlinear device. A correction value is calculated based on the phase of the transmission data signal when the voltage controlled oscillator is stably oscillated by forming a PLL and the phase of the reception data signal, and between the first transceiver and the second transceiver. A distance measuring device that is a means for calculating a first distance based on a phase of a transmission data signal when a voltage-controlled oscillator is stably oscillated by forming a PLL and a phase of a reception data signal .

  Forming a PLL between the first transceiver and the second nonlinear device means that a transmission data signal, or a divided signal or multiplied signal thereof, and an equivalent received data signal, or a divided signal or multiplied signal thereof, It means that the phase is synchronized.

  In a fifth aspect based on the first aspect or the third aspect, the first transmission device has a modulation device that generates a high-frequency signal by modulating a carrier wave with a transmission data signal, and the first reception device returns a reply A distance measuring device comprising a demodulating device for demodulating a signal to obtain a received data signal.

  In a sixth aspect based on the second aspect or the fourth aspect, the first transmission device has a modulation device that generates a high frequency signal by modulating a carrier wave with a transmission data signal, and the first reception device returns a reply A distance measuring device comprising a demodulator that demodulates a signal and an equivalent reply signal to obtain a received data signal and an equivalent received data signal, respectively.

  The modulation method is preferably ASK modulation, FSK modulation, PSK modulation, or frequency modulation.

  In a seventh aspect based on the first aspect, the data signal generation device is a device that generates a transmission data signal whose frequency changes in a triangular wave. The first transmission device frequency-modulates a carrier wave using the transmission data signal. The FM-CW signal obtained in this way is a high-frequency signal, the first receiving device has a demodulating device that demodulates the return signal to obtain a received data signal, and the distance calculation device is a transmission data signal. And a distance measuring device that calculates a first distance based on a frequency difference from the received data signal.

  In an eighth aspect based on the second aspect, the data signal generation device is a device that generates a transmission data signal whose frequency changes in a triangular wave, and the first transmission device frequency-modulates the carrier wave with the transmission data signal. The first receiving device has a demodulating device that obtains a received data signal and an equivalent received data signal by frequency-demodulating the returned signal and the equivalent returned signal. The distance calculation device calculates a first distance based on a frequency difference between a transmission data signal and a reception data signal, and calculates the correction value based on a frequency difference between the transmission data signal and the equivalent reception data signal. It is a distance measuring device characterized by being.

  In a ninth aspect based on the first to eighth aspects, the modulation device is a balanced modulator that outputs two high-frequency signals having different frequencies obtained by balanced modulation of a carrier wave using a transmission data signal, and a reply The signal is a distance measuring device characterized by being an intermodulation wave of the two high-frequency signals.

  By using a balanced modulator, it is possible to easily generate two signals having synchronized phases and different frequencies, and an intermodulation wave can be generated by a non-linear device using the two signals.

  A tenth aspect of the present invention is the distance measuring device according to any one of the first to eighth aspects, wherein the return signal is a second harmonic.

  When using harmonics, it is desirable that the second harmonic is a small frequency difference from the high frequency signal.

  An eleventh invention is the distance measuring device according to the ninth invention, wherein the return signal is a third-order intermodulation wave.

  When using an intermodulation wave, a third-order intermodulation wave is desirable because the frequency difference from a high-frequency signal is small.

  In a twelfth aspect based on the first to eleventh aspects, the second transmitter / receiver performs ASK modulation on the received high-frequency signal by switching between transmission and non-transmission based on its own ID information, and the reply signal The first transmitter / receiver has an identification device for identifying the second transmitter / receiver by demodulating the ASK-modulated return signal to obtain the ID information of the second transmitter / receiver. Is a distance measuring device characterized by

  A thirteenth aspect of the present invention is a distance measuring device according to the first to twelfth aspects of the present invention, wherein the first transceiver is an IC tag reader and the second transceiver is an IC tag.

  A fourteenth aspect of the invention is a first transceiver used in the distance measuring device in the first to thirteenth aspects of the invention.

  A fifteenth aspect of the present invention is a second transceiver used in the distance measuring device according to the first to thirteenth aspects of the present invention.

  According to the first invention, since the second transmitter / receiver has the first nonlinear device, the frequency of the high-frequency signal transmitted from the first transmitter / receiver is different from the frequency of the return signal received. Therefore, the reflected wave (same frequency as the high frequency signal) from other than the second transmitter / receiver can be distinguished from the return signal from the second transmitter / receiver, and interference can be prevented, so that the accuracy of distance measurement can be improved. In addition, since the distance is measured using the first and second transceivers, there is no problem that distance measurement is difficult when the object is difficult to reflect radio waves. In addition, since the frequency is converted using a non-linear device, the configuration of the second transceiver is very simple.

  Further, according to the second invention, the distance in which the delay error is corrected by the internal circuit of the first transmitter / receiver and the second transmitter / receiver can be obtained, and the accuracy can be further improved. Further, as in the third aspect, by forming the PLL, the frequency control of the signal is facilitated, and the phase difference detection accuracy is improved. Further, as in the fourth invention, the second invention and the third invention are combined to correct the delay error by the internal circuit of the first transmitter / receiver and the second transmitter / receiver and to detect the phase difference. Can be improved.

  As in the fifth and sixth inventions, when the carrier wave is modulated by the transmission data signal and then transmitted, the distance can be easily measured even if the communication environment between the first transceiver and the second transceiver is poor. This can also be used to identify the second transceiver. That is, the ID information is transmitted as a transmission data signal, for example, by ASK modulation, and the second transmitter demodulates the ID information. Then, the ID signal is collated with its own ID information, and if it matches, the reply signal generated by the first nonlinear device is transmitted, and if it does not match, it is not transmitted. The first transmitter / receiver can identify the second transmitter / receiver based on whether or not the reply signal is received. When both this identification and distance measurement are used, the distance can be measured only for a specific second transceiver among the plurality of second transceivers.

  Further, like the seventh and eighth inventions, the present invention can also be applied to distance measurement by the FM-CW method. According to the present invention, since it can be distinguished from DC noise, a short distance can be measured rather than a distance measurement by the conventional FM-CW method.

  When using harmonics, it is desirable to use second harmonics as in the tenth invention. Further, it is more desirable to use an intermodulation wave as in the ninth invention, and a third-order intermodulation wave is more desirable as in the eleventh invention. This is because the frequency difference between the high-frequency signal and the transmission signal is small, so that it can be within the same band, and it is easy to satisfy the wireless standard. Further, the same antenna can be used as a transmitting device and a receiving device.

  According to the twelfth aspect, distance measurement and identification of the second transceiver can be performed simultaneously.

  As in the thirteenth aspect of the present invention, the present invention can be applied to an IC tag system using the first transceiver as an IC tag reader and the second transceiver as an IC tag. In particular, even if the IC tag is a passive type, the distance from the IC tag reader to the IC tag can be measured.

  Hereinafter, specific examples of the present invention will be described with reference to the drawings. However, the present invention is not limited to these examples.

  FIG. 1 is a block diagram illustrating the configuration of the distance measuring apparatus according to the first embodiment. FIG. 1 a shows the configuration of the first transceiver 10, and FIG. 1 b shows the configuration of the second transceiver 20.

  A first transceiver 10 shown in FIG. 1 a includes a crystal oscillator 101, phase comparators 102 and 118, loop filters 103 and 119, a VCO (voltage controlled oscillator) 104, a 1 / A frequency divider 105, and a balanced modulator 106. , Amplifiers 107 and 114, filters 108 and 112, switches 109 and 113, transmission antenna 110, nonlinear device 111, reception antenna 115, 1 / B divider 116, 1 / C divider 117, and signal processing device 1 Has been. Here, it is assumed that the nonlinear device 111 has at least third-order distortion.

  The crystal oscillator 101, the phase comparator 102, the loop filter 103, the VCO 104, and the 1 / A frequency divider 105 correspond to the data signal generator of the present invention. The VCO 104, the balanced modulator 106, the amplifier 107, the filter 108, and the transmission antenna 110 correspond to the first transmission device of the present invention. The receiving antenna 115 and the 1 / C frequency divider 117 correspond to the first receiving device of the present invention. The 1 / B frequency divider 116, the phase comparator 118, the loop filter 119, and the signal processing device 1 correspond to the distance calculation device of the present invention. The nonlinear device 111 and the filter 112 correspond to the second nonlinear device of the present invention.

  The switch 109 receives the output from the filter 108 and can switch the output to either the transmission antenna 110 or the nonlinear device 111. The switch 113 can switch the input to either the reception antenna 115 or the filter 112 and is output to the 1 / C frequency divider 117. The switch 109 and the switch 113 are linked, and when the output of the switch 109 is the transmission antenna 110, the input of the switch 113 is the reception antenna 115, and when the output of the switch 109 is the nonlinear device 111, the input of the switch 113 Becomes the filter 112.

  When the switch 109 is an output to the nonlinear device 111 and the switch 113 is an input to the filter 112, the phase comparator 102, the loop filter 103, the VCO 104, and the 1 / C frequency divider 117 pass through the nonlinear device 111. A PLL is formed.

  The second transceiver 20 shown in FIG. 1b includes a receiving antenna 120, an amplifier 121, a nonlinear device 122, a filter 123, and a transmitting antenna 124. The nonlinear device 122 has the same characteristics as the nonlinear device 111. The receiving antenna 120 corresponds to the second receiving apparatus of the present invention, and the nonlinear device 122, the filter 123, and the transmitting antenna 124 correspond to the first nonlinear device of the present invention.

The crystal oscillator 101 generates a signal of frequency f, and based on the signal, the VCO 104 generates a signal of frequency f ₀ (corresponding to the transmission data signal of the present invention). Since the PLL is formed, f ₀ is f ₀ = AC / (A−3) · f. The signal is converted to a signal having a frequency Δf (Δf = f ₀ / A) by the 1 / A frequency divider 105, and the signal having the original frequency f ₀ is modulated by the balanced modulator 106 by the signal having the frequency Δf, and the frequency f _{1 is obtained.} Two signals (corresponding to the high-frequency signal of the present invention) of f ₂ (f ₂ = f ₀ + Δf) are generated (f ₁ = f ₀ −Δf). When the switch 109 is an output to the nonlinear device 111, the two signals having the frequencies f ₁ and f ₂ are input to the nonlinear device 111 having at least third-order distortion, and the frequencies 2f ₁ -f ₂ and 2f ₂ -f ₁ 3f intermodulation waves of 2f ₁ + f ₂ and 2f ₂ + f ₁ are output. By the frequency selection function by the filter 112 and the PLL, only the signal of frequency 2f ₁ -f ₂ (corresponding to the equivalent reply signal of the present invention) is passed, and the frequency (2f ₁ -f ₂ ) / C is obtained by the 1 / C frequency divider 117. = (F ₀ −3Δf) / C signal (corresponding to the equivalent received data signal of the present invention) and input to the phase comparator 102. Therefore, the frequency and phase of the signal generated by the VCO 104 are controlled so that this signal and the signal generated by the crystal oscillator 101 are phase-synchronized.

A smaller Δf is desirable. The difference between f ₁ and f ₂ is reduced, and f ₁ and f ₂ and their third-order intermodulation waves are in the same band, and the same antenna can be used for the transmitting antennas 110 and 124 and the receiving antennas 115 and 120. In that case, the transmission antenna 110 and the reception antenna 115 and the reception antenna 120 and the transmission antenna 124 can be shared by using a circulator. Although only the signal of the frequency 2f ₁ -f ₂ is passed by the frequency selection function by the filter 112 and the PLL, only the signal of the frequency 2f ₂ -f ₁ may be passed. Although an intermodulation wave of 5th order or higher may be used, it is not desirable because it becomes difficult to make it fall within the same band as f ₁ and f ₂ .

  The phase comparator 118 detects the phase difference (φ) between the signal output from the VCO 104 and the frequency f by the 1 / B frequency divider 116 and the signal output from the crystal oscillator 101, and the loop filter 119. Through the signal processing device 1, a phase difference φ is detected. This phase difference φ reflects an error based on signal delay in the internal circuit of the first transmitter / receiver 10 and the second transmitter / receiver 20 and becomes a distance correction value.

When the above frequencies and frequency division numbers are expressed by specific numerical values, when f = 10 MHz, A = 10, and C = 14, f ₀ = 200 MHz, Δf = 20 MHz, f ₁ = 180 MHz, f ₂ = 220 MHz, 2f ₁ −f ₂ = 140 MHz, B = 20.

On the other hand, when the switch 109 is an output to the transmission antenna 110, communication is performed between the first transceiver 10 and the second transceiver 20, and a PLL is formed via the second transceiver 20. . The two signals having the frequencies f ₁ and f ₂ transmitted from the transmission antenna 110 are received by the reception antenna 120 of the second transceiver 20 and input to the nonlinear device 122. Of the intermodulation wave generated by the non-linear device 122, only the signal of frequency 2f ₁ -f ₂ (corresponding to the return signal of the present invention) is passed by the frequency selection function by the filter 123 and PLL and transmitted by the transmitting antenna 124. . The transmitted signal having the frequency 2f ₁ -f ₂ is received by the receiving antenna 115 of the first transmitter / receiver 10, and the 1 / C frequency divider 117 receives the signal having the frequency (2f ₁ -f ₂ ) / C (the present invention). (Received data signal) is input to the phase comparator 102. Also in this case, the frequency and phase of the signal generated by the VCO 104 are synchronized so that the signal from the 1 / C frequency divider 117 and the signal generated by the crystal oscillator 101 are phase-synchronized by the PLL via the second transceiver 20. The frequency f ₀ of the signal that is controlled and output from the VCO 104 is f ₀ = AC / (A−3) · f.

  Similarly, the signal processing device 1 detects the phase difference between the signal output from the VCO 104 and having the frequency f by the 1 / B divider 116 and the signal output from the crystal oscillator 101.

  At this time, if the phase difference detected by the signal processing device 1 is ψ, the phase difference ψ is the phase delay corresponding to the distance between the first transmitter / receiver 10 and the second transmitter / receiver 20 and the first transmitter / receiver 10. And the delay of the phase by the internal circuit of the 2nd transmitter / receiver 20 is reflected. The phase difference φ is a phase delay when the distance between the first transceiver 10 and the second transceiver 20 is zero, that is, a signal delay in the internal circuit of the first transceiver 10 and the second transceiver 20. Therefore, by setting ψ−φ, the error due to the phase delay of the internal circuit of the first transmitter / receiver 10 and the second transmitter / receiver 20 can be corrected, and the first transmitter / receiver 10 and the second transmitter / receiver can be corrected. The distance from the machine 20 can be obtained with high accuracy.

In the distance measurement of the first embodiment, the frequency of the signal transmitted by the first transmitter / receiver 10 is f ₁ and f ₂ , and the frequency of the received signal is 2f ₁ −f _2. It can be distinguished from the reflected wave from, and there is no interference.

  FIG. 2 is a block diagram illustrating a configuration of the first transmitter / receiver 30 in the distance measuring apparatus according to the second embodiment. The 1 / A frequency divider 105 and the balanced modulator 106 are omitted from the configuration of the first transceiver 10 of the first embodiment, and the 1 / E frequency divider 200 and the 1 / C frequency divider are replaced with the 1 / B frequency divider 116. In this configuration, the 1 / D frequency divider 201 is used instead of the device 117. The second transceiver has the same configuration as that of the first embodiment. The crystal oscillator 101, the phase comparator 102, the loop filter 103, and the VCO 104 correspond to the data signal generator of the present invention. The VCO 104, the amplifier 107, the filter 108, and the transmission antenna 110 correspond to the first transmission device of the present invention. The receiving antenna 115 and the 1 / D frequency divider 201 correspond to the first receiving device of the present invention. The 1 / E frequency divider 200, the phase comparator 118, the loop filter 119, and the signal processing device 1 correspond to the distance calculation device of the present invention.

In the first embodiment, a third-order intermodulation wave having a frequency of 2f ₁ -f ₂ is used. In the second embodiment, a second-order harmonic is used. Since one signal is input to the non-linear devices 111 and 122, a harmonic is output, but only the second harmonic is passed through the filters 112 and 123. In the third and higher harmonics, the frequency difference with the frequency of the signal transmitted by the first transceiver 30 is not desirable because it is large.

The point that the phase difference is detected by forming the PLL and the distance is obtained from the phase difference is the same as in the first embodiment. That is, the frequency and phase of the signal generated by the VCO 104 are controlled so that the signal from the 1 / D frequency divider 201 and the signal generated by the crystal oscillator 101 are phase-synchronized. The signal generated by the VCO 104 in a state where the PLL is formed is set to the same frequency as the frequency f of the signal generated by the crystal oscillator 101 by the 1 / E frequency divider 200, and the phase difference from the signal output from the crystal oscillator 101 Is detected by the signal processing device 1. The distance is obtained from the detected phase difference. Further, the same as the signal transmitted in the first transceiver 30 (frequency f _0), and also in Example 1 that no interference due to the difference in frequency between the received the second harmonic (frequency 2f _0).

When the above frequencies and frequency division numbers are shown by specific numerical values, when f = 10 MHz and D = 30, f ₀ = 150 MHz, the frequency of the second harmonic is 300 MHz, and E = 15.

  FIG. 3 is a block diagram illustrating the configuration of the first transmitter / receiver 40 in the distance measuring apparatus according to the third embodiment. The configuration of the second transceiver is the same as that of the first embodiment.

  The difference between the first transceiver 10 and the first transceiver 40 is that, instead of the 1 / A divider 105 and the 1 / B divider 116, a 1 / M divider 300 and a 1 / N divider are used. 301 is provided, and a waveform shaper 302, a demodulator 303, and a carrier wave regenerator 306 for newly obtaining a rectangular wave are provided. Therefore, the balanced modulator 106 generates a signal obtained by ASK modulating the signal from the VCO 104 with the rectangular wave from the waveform shaper 302. Another difference is that the switches 109 and 113, the nonlinear device 111, the filter 112, the transmission antenna 110, and the reception antenna 115 are omitted, and a circulator 304 and a transmission / reception antenna 305 that shares transmission and reception are provided. The frequency M of the output signal from the 1 / M frequency divider 300 is determined to be equal to f, and the output signal from the 1 / M frequency divider 300 and the output of the crystal oscillator 101 are determined. The distance is measured from the phase difference with the signal.

  The crystal oscillator 101, the phase comparator 102, the loop filter 103, the VCO 104, the 1 / M frequency divider 300, and the waveform shaper 302 correspond to the data signal generator of the present invention. The VCO 104, the balanced modulator 106, the amplifier 107, the filter 108, and the transmission / reception antenna 305 correspond to the first transmission device of the present invention. The transmission / reception antenna 305, the demodulator 303, the carrier wave regenerator 306, and the 1 / N frequency divider 301 correspond to the first receiving device of the present invention. The phase comparator 118, the loop filter 119, and the signal processing device 1 correspond to the distance calculation device of the present invention.

The PLL between the first transceiver 40 and the second transceiver is the same as in the first embodiment. That is, the frequency and phase of the signal generated by the VCO 104 are controlled so that the signal from the 1 / N frequency divider 301 and the signal generated by the crystal oscillator 101 are phase-synchronized. The signal generated by the VCO 104 in a state where the PLL is formed is set to the same frequency as the frequency f of the signal generated by the crystal oscillator 101 by the 1 / M frequency divider 300, and the phase difference from the signal output from the crystal oscillator 101 Is detected by the signal processing device 1. The distance is obtained from the detected phase difference. The first transmitter / receiver transmits two signals of frequencies f ₁ and f ₂ and receives a signal of frequency 2f ₁ -f ₂ as in the first embodiment. In the third embodiment, since the ASK modulated signal is transmitted / received by the transmission / reception antenna 305, the distance can be measured even if the communication environment between the first transceiver 40 and the second transceiver is bad.

  In the above first to third embodiments, the PLL is configured so that the received data signal is phase-synchronized with the reference signal output from the crystal oscillator 101, and the phase difference between the reference signal and the transmission data signal is detected to determine the distance. Looking for. In this configuration, it is possible to extract only the reply signal from the signal close to the frequency of the reply signal that cannot be removed by the filter 112 by the frequency selection function using the PLL. Conversely, the PLL may be configured to synchronize the phase of the transmission data signal with the reference signal output from the crystal oscillator 101, and the distance may be obtained by detecting the phase difference between the reference signal and the reception data signal. Good. However, in this case, a signal close to the frequency of the reply signal cannot be removed.

  FIG. 4 is a block diagram illustrating the configuration of the first transceiver 50 in the distance measuring apparatus according to the fourth embodiment. The configuration of the second transceiver is the same as that of the first embodiment.

  The first transceiver 50 includes an oscillator 400, a frequency modulator 401, a balanced modulator 402, 408, 411, amplifiers 403, 407, a circulator 404, filters 405, 409, a transmission / reception antenna 406, a 1/3 frequency divider 410, 1 / F frequency divider 412 and signal processing device 1. The oscillator 400, 1 / F frequency divider 412, and frequency modulator 401 correspond to the data signal generator of the present invention, and the balanced modulator 402, amplifier 403, filter 405, and transmission / reception antenna 406 correspond to the first transmission of the present invention. It corresponds to a device. The filter 405, the transmission / reception antenna 406, the balanced modulator 408, the filters 405 and 409, and the 1/3 frequency divider 410 correspond to the first receiving device of the present invention. Further, the balanced modulator 411 and the signal processing device 1 correspond to the distance calculation device of the present invention.

The frequency modulator 401 receives a triangular wave on the time axis, frequency-modulates the signal from the 1 / F frequency divider 412 with the triangular wave, and generates a transmission data signal whose frequency changes with the triangular wave. The fluctuation range of the frequency is Δf, and the center frequency is 1 / F of the frequency f ₀ of the carrier wave from the oscillator 400. Hereinafter, it is assumed that the frequency is Δf (t). The carrier wave from the oscillator 400 is modulated by the balanced modulator 402 by this transmission data signal to generate two signals having different reference frequencies (signals of frequencies f ₀ + Δf (t) and f ₀ −Δf (t)), and are transmitted and received. It is transmitted to the second transceiver 20 by the antenna 406. The second transceiver 20 generates and transmits a third-order intermodulation wave using a nonlinear device. The third-order intermodulation wave (frequency f ₀ + 3Δf (t)) received by the transmission / reception antenna 406 from the first transmitter / receiver 20 is demodulated by the balanced modulator 408 using the signal from the oscillator 400, and the frequency is 3Δf (t). The transmission data signal is demodulated. This signal is returned to Δf (t) by the 1/3 frequency divider 410, and a beat signal is generated by the balanced modulator 411 using the transmission data signal from the modulator 401. By processing this beat signal by the signal processing device 1, the distance between the first transceiver 50 and the second transceiver 20 is measured.

  In the embodiment, the first transmitter / receiver is an IC tag reader and the second transmitter / receiver is an IC tag, so that the present invention can be used for measuring the distance of the IC tag.

  In the embodiment, a switch may be provided between the filter 123 and the transmission antenna 124 of the second transceiver. Based on the ID information of the second transmitter / receiver, the signal output from the filter 123 is ASK modulated by this switch, and the ID information is demodulated in the first transmitter / receiver, thereby identifying the second transmitter / receiver together with the distance measurement. It becomes possible to do. Further, in the third embodiment, the signal from the VCO 104 is modulated by the signal from the waveform shaper 302 including the ID information, the ID information is demodulated by the second transmitter / receiver, and compared with the second transmitter / receiver. In this case, the second transmitter / receiver can be identified by switching the transmission on and the non-transmission by turning the switch on and turning it off if they do not match.

  In the first and second embodiments, when the phase delay due to the internal circuit is ignored without correction, the switches 109 and 113, the nonlinear device 111, and the filter 112 are unnecessary, and the filter 108, the transmission antenna 110, and the reception antenna are omitted. 115 and 1 / C frequency divider 117 or 1 / D frequency divider 200 are directly connected. In the third and fourth embodiments, when it is desired to correct the phase delay due to the internal circuit, a non-linear device may be provided in the first transceiver as in the first and second embodiments and switched by a switch. In the third embodiment, FSK modulation, PSK modulation, and frequency modulation may be used instead of ASK modulation.

  In the first to third embodiments, the PLL is formed between the first transmitter / receiver and the second transmitter / receiver. However, the PLL is not necessarily formed.

  The present invention can be applied to distance measurement using an IC tag. In particular, the distance can be measured using a passive IC tag.

1 is a block diagram illustrating a configuration of a distance measuring device according to Embodiment 1. FIG. The block diagram which shows the structure of a 1st transmitter / receiver among the distance measuring devices of Example 2. FIG. The block diagram which shows the structure of a 1st transmitter / receiver among the distance measuring devices of Example 3. FIG. The block diagram which shows the structure of a 1st transmitter / receiver among the distance measuring devices of Example 4. FIG.

Explanation of symbols

1: Distance calculator 10, 30, 40, 50: First transceiver 20: Second transceiver 101: Crystal oscillator 102, 118: Phase comparator 103, 119: Loop filter 104: VCO
105, 116, 117, 200, 201, 300, 301, 410, 412: Frequency divider 106, 402, 408, 411: Balanced modulator 108, 112, 123, 405, 409: Filter 109, 113: Switch 110, 124: Transmitting antenna 111, 122: Non-linear device 115, 120: Receiving antenna 302: Waveform shaper 303: Demodulator 304, 404: Circulator 305, 406: Transmission / reception antenna 306: Carrier regenerator 401: Frequency modulator

Claims (15)

In a distance measuring device configured by a first transceiver and a second transceiver, and measuring a distance between the first transceiver and the second transceiver,
The first transceiver is
A data signal generator for generating a low-frequency transmission data signal;
A first transmitter for generating a high-frequency signal from the transmission data signal and transmitting the high-frequency signal;
A first receiver for receiving a reply signal from the second transceiver and converting the received signal into a low-frequency received data signal;
A distance computing device for obtaining a first distance between the first transceiver and the second transceiver based on the received data signal and the transmitted data signal obtained by the first receiver;
Have
The second transceiver is
A second receiver that receives the high-frequency signal transmitted from the first transmitter;
A first non-linear device that converts the high-frequency signal output from the second receiving device to a different frequency according to non-linear characteristics related to input and output and sends the reply signal;
A distance measuring device comprising: The first transceiver has a second nonlinear device having the same characteristics as the first nonlinear device of the second transceiver, which receives the high-frequency signal and outputs an equivalent reply signal equivalent to the reply signal. And inputting the equivalent return signal to the first receiving device to output a low-frequency equivalent received data signal,
The distance calculation device obtains a correction value obtained based on the transmission data signal and the equivalent reception data signal, and obtains a value obtained by subtracting the correction value from the first distance between the first transceiver and the second transceiver. The distance measuring device according to claim 1, wherein the distance is a normal distance. The first transmission device includes a voltage controlled oscillator for generating the high frequency signal,
The distance calculation device includes:
Based on the phase of the transmission data signal and the phase of the reception data signal when a PLL is formed between the first transceiver and the second transceiver and the voltage-controlled oscillator is stably oscillated, A device that calculates one distance;
The distance measuring device according to claim 1. The first transmission device includes a voltage controlled oscillator for generating the high frequency signal,
The distance calculation device includes:
Based on the phase of the transmission data signal when the voltage-controlled oscillator is stably oscillated by forming a PLL between the first transceiver and the second nonlinear device, and the phase of the equivalent reception data signal Calculate the correction value,
Based on the phase of the transmission data signal when a PLL is formed between the first transceiver and the second transceiver to stably oscillate the voltage-controlled oscillator, and the phase of the reception data signal, The distance measuring device according to claim 2, wherein the distance measuring device is a means for calculating a first distance. The first transmission device includes a modulation device that generates a high-frequency signal by modulating a carrier wave with the transmission data signal,
The distance measuring device according to claim 1, wherein the first receiving device includes a demodulating device that demodulates the return signal to obtain the received data signal. The first transmission device includes a modulation device that generates a high-frequency signal by modulating a carrier wave with the transmission data signal,
The said 1st receiver has a demodulator which demodulates the said reply signal and the said equivalent reply signal, respectively, and obtains the said received data signal and the said equivalent received data signal, respectively. 4. The distance measuring device according to 4. The data signal generator is a device that generates the transmission data signal whose frequency changes with a triangular wave,
The first transmission device includes a modulation device that uses an FM-CW signal obtained by frequency-modulating the carrier wave as the high-frequency signal, using the transmission data signal,
The first receiver has a demodulator that demodulates the return signal to obtain the received data signal,
The distance measuring device according to claim 1, wherein the distance calculating device is a device that calculates the first distance based on a frequency difference between the transmission data signal and the received data signal. The data signal generator is a device that generates the transmission data signal whose frequency changes with a triangular wave,
The first transmission device includes a modulation device that uses an FM-CW signal obtained by frequency-modulating the carrier wave as the high-frequency signal, using the transmission data signal,
The first receiving apparatus includes a demodulating apparatus that obtains the received data signal and the equivalent received data signal by frequency-demodulating the return signal and the equivalent returned signal,
The distance calculation device calculates the first distance based on a frequency difference between the transmission data signal and the reception data signal, and calculates the correction value based on a frequency difference between the transmission data signal and the equivalent reception data signal. The distance measuring device according to claim 2, wherein the distance measuring device is a means for calculating. The modulation device is a balanced modulator that outputs two high-frequency signals having different frequencies obtained by balanced modulation of the carrier wave with the transmission data signal,
The reply signal is an intermodulation wave of the two high-frequency signals;
The distance measuring device according to any one of claims 1 to 8, wherein   The distance measuring device according to claim 1, wherein the reply signal is a second harmonic.   The distance measuring device according to claim 9, wherein the reply signal is a third-order intermodulation wave. The second transceiver has a transmission switching device that ASK modulates the high-frequency signal received by switching between transmission and non-transmission based on its own ID information, and transmits it as the reply signal,
The first transmitter / receiver has an identification device for identifying the second transmitter / receiver by demodulating the ASK-modulated return signal to obtain the ID information of the second transmitter / receiver;
The distance measuring device according to claim 1, wherein:   The distance measuring device according to any one of claims 1 to 12, wherein the first transceiver is an IC tag reader and the second transceiver is an IC tag.   The 1st transmitter / receiver used for the distance measuring apparatus of any one of the said Claim 1 thru | or 13.   The 2nd transmitter / receiver used for the distance measuring apparatus of any one of the said Claim 1 thru | or 13.

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