JP4952387B2 - Distance measuring device - Google Patents

Description

  The present invention relates to an apparatus for measuring a distance between two transmitters / receivers by combining the two transmitters / receivers.

As a technique for measuring the distance to an object by receiving a reflected wave from the object using a radio wave or an ultrasonic wave and detecting or adjusting a phase difference from the transmitted wave, the following Patent Documents 1 to 3 are provided. Is mentioned.
JP 2004-198306 A JP 2005-308694 A Japanese Patent Laying-Open No. 2005-091214

  The technique of Patent Document 1 forms a PLL (Phase Locked Loop) between a transceiver and a reflector. The reflected wave reflected by the transmitted radio wave or ultrasonic wave hits the object to be measured is divided and compared with the reference signal. The comparison result is input as a control voltage of a voltage controlled oscillator (VCO) through a loop filter (LPF as an integrator is used). An example using modulation / demodulation is also shown.

  The technology of Patent Document 2 is a distance sensor by PLL formation using ultrasonic waves. The phase of the reflected wave and the transmitted wave is compared.

  The technique of Patent Document 3 measures a distance from a logical product of a reflected light from a measurement target of pulsed light having a frequency four times that of a reference signal and a pulsed light having a frequency five times that of the reference signal, and the reference signal. Is.

  Patent Documents 1 to 3 all use a reflected wave from a measurement target. Then, it becomes difficult to perform distance measurement when there is an obstacle between the measurement object and the measurement apparatus that does not reflect radio waves and ultrasonic waves or between the measurement object and the measurement apparatus. In this respect, it is limited to short distance measurements.

  In addition, since the transmitted wave and the received wave use the same frequency wave, the reflected wave from the measurement object cannot be identified when there is reflection from other than the measurement object. Moreover, when the transmitting antenna and the receiving antenna are arranged close to each other (when the measuring device is small), there is a concern that the transmitted radio wave (ultrasonic wave) may be directly received.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a distance measuring device that enables distance measurement even when there are obstacles between them. It is another object of the present invention to provide a distance measuring device that can measure a long distance. Furthermore, even if it is necessary to make the frequency of a signal carried on a carrier wave low due to legal regulations, the object is to perform phase comparison at those intermediate frequencies.

The invention according to claim 1 is a distance measuring device comprising a first transceiver (1000) and a second transceiver (2000),
The first transceiver (1000)
Reference signal oscillators (100 and 106) for generating a reference signal of frequency f ₀ / R (R is a natural number), a phase comparator (11) in which one of the two inputs is a reference signal, and a phase comparator (11) And a voltage for generating a carrier wave having a frequency f ₁ = Nf ₀ / R based on the output of the integrator or the low-pass filter (12). A controlled oscillator (13) and a 1 / N frequency divider (N) that generates a signal of frequency f ₁ / N = f ₀ / R from a carrier of frequency f ₁ = Nf ₀ / R output from the voltage controlled oscillator (13) Is an integer greater than or equal to 2) (14) and the transmission data signal D _T of frequency f ₁ / MN = f ₀ / MR (M is an integer greater than or equal to 1000) based on the output of the 1 / N frequency divider (14). A 1 / M frequency divider (15) to generate and a carrier wave having a frequency f ₁ = Nf ₀ / R as a transmission data signal D _T From the received signal obtained by modulating the carrier wave of frequency f ₂ (≠ f ₁ ) received from the first modulator (110) modulated by the second transmitter / receiver (2000), the frequency f ₁ / MN = f ₀ / MR first synchronous demodulator for demodulating a received data signal D _R with (160), the received data signal D _R of the output frequency _{f 1 / MN = f 0 /} MR of the first synchronous demodulator (160) A first frequency converter (170) comprising a PLL that generates a signal of frequency f ₁ / N = f ₀ / R from
The second transmitter / receiver (2000) uses the demodulated data of frequency f ₁ / MN = f ₀ / MR by synchronous demodulation from the received signal modulated from the carrier of frequency f ₁ received from the first transmitter / receiver (1000). second synchronous demodulator for demodulating the signal D ₂ and (260), from the frequency _{f 1 / MN = f 0 /} MR of the folded data signal D ₂ that output of the second synchronous demodulator (260), frequency-converted frequency f ₂ (≠ f ₁₎ second frequency converter consisting of PLL for generating a carrier wave and (270), a second modulator for modulating the data signal D ₂ folding carrier frequency f ₂ (≠ f ₁₎ ( 210)
The other of the two inputs of the phase comparator (11) is the output of the first frequency converter (170),
The phase comparator (11), integrator or low-pass filter (12), voltage controlled oscillator (13), and 1 / N frequency divider (14) are connected to the transmission data signal D _T of the first transceiver, the second via the received data signal D _R of the transceivers of the folded data signal D ₂ and the first transceiver, the output frequency _{f 1 / N = f 0 /} R of the signal of the phase of the first frequency converter (170) And the reference signal oscillator (100 and 106) output the PLL so that the phase of the reference signal of the frequency f ₀ / R matches.
The output of the 1 / N frequency divider (14), the reference signal of the frequency f ₀ / R output from the reference signal oscillator (100 and 106), or the frequency f ₁ / N output from the first frequency converter (170) = A distance measuring apparatus that measures a distance between a first transceiver and a second transceiver by detecting a phase difference with an f ₀ / R signal.

In the invention according to claim 2, the first modulator (110) and the second modulator (210) are a PSK modulator or a QPSK modulator,
The first synchronous demodulator (160) and the second synchronous demodulator (260) are a PSK synchronous demodulator or a QPSK synchronous demodulator.
The invention according to claim 3 is the distance measuring device according to claim 1, wherein both the first modulator (110) and the second modulator (210) are FM modulators, and the first synchronous demodulator (160). And the second synchronous demodulator (260) are both replaced by an FM demodulator.
The invention according to claim 4 is the distance measuring device according to claim 1, wherein the first modulator (110), the second modulator (210), the first synchronous demodulator (160), the second synchronous demodulator ( 260) is a distance measuring device characterized in that switching between the above configuration and a normal communication device is possible.

When a data signal obtained by modulating the first carrier wave transmitted from the first transceiver is demodulated by the second transceiver, the second carrier wave is modulated by the second carrier wave, and then reversely transmitted, and then demodulated by the first transceiver. A phase difference (time difference) corresponding to the transmission / reception distance (twice the distance between the first and second transmitters / receivers) occurs between the two round-trip transmissions / receptions. At this time, a PLL is formed between the first transceiver and the second transceiver, the voltage controlled oscillator (VCO) is stably oscillated, and the transmission data generated by frequency division from the output of the VCO 13 is generated. It is preferable to detect the phase difference between the signal and the received data signal, but the data signal at this time is regulated by domestic laws and others, and for example, in the carrier wave of about 1 GHz, the data signal is more than a dozen kHz due to the bandwidth limitation Must be less than or equal to. Therefore, two-stage frequency division is performed from the VCO output (frequency f ₁ ). In the first stage, it is assumed that the frequency is reduced to, for example, about 1 to several tens of MHz (f ₁ / N), and the data signal is set to, for example, about ten or less kHz (f ₁ / MN). Thus, the data signal _DT is transmitted / received, for example, at a frequency of about 10 kHz or less (f ₁ / MN), and in accordance with the band limitation laws and regulations, the digit comparison is performed in the phase comparison. Considering the above, those of about 1 to several tens of MHz (f ₁ / N) are compared with each other. At this time, the comparison with the first-stage frequency-divided signal (frequency f ₁ / N) of the VCO output is the reference signal of the frequency f ₀ / R output from the reference signal oscillator and the output of the first frequency converter. Any of the signals of the frequency f ₁ / N = f ₀ / R to be used may be used. This is so that the phase of the signal of the frequency f ₁ / N = f ₀ / R output from the first frequency converter matches the phase of the reference signal of the frequency f ₀ / R output from the reference signal oscillator. transmitting the data signal D _T of 1 transceiver, via the received data signal D _R of the second transceiver of the folded data signal D ₂ and the first transceiver, 1 / N divider and the first frequency converter This is because it is controlled by the PLL.

According to the present invention described above, the time difference (phase difference) of the data signal having a lower frequency (frequency f ₁ / MN) is detected by the M-multiplied signal, and the higher frequency (frequency f ₁ ) is used for the carrier wave. It is only necessary that the low-frequency data signal can be demodulated, and the distance can be measured with high accuracy. In addition, a device that does not reflect radio waves can be set as a distance measurement target by mounting the second transceiver. Since the frequency at which the diffraction effect can be expected is used as a carrier wave, it is strong against a barrier and noise between the first and second transceivers, so that the second transceiver is buried in a place where it cannot be directly seen. Even in the case of distance measurement. If a high frequency of 800 MHz or less that can be expected to have a diffraction effect is used as a carrier wave, the distance can be measured by diffracting the obstacle. Note that there is no interference because transmissions from the first transceiver to the second transceiver and reverse transmission from the second transceiver to the first transceiver use different frequency carriers. That is, unlike the technique of receiving a reflected wave, there is no reverse transmission from anything other than the object to be measured. Further, the measurement distance range can be easily changed by changing the frequency (f ₁ / MN) of the data signal _DT .
The phase comparison for distance measurement can be performed at a frequency f ₁ / N intermediate between the carrier frequency f ₁ and the data signal frequency f ₁ / MN. For example, the frequency f ₁ / MN of the data signal is set by legal regulation. Even when it must be set very low, the frequency f ₁ / N used for phase comparison for distance measurement can be freely designed according to the distance to be measured. For example, if the carrier wave is about 1 GHz, the data signal must be about a dozen kHz or less. For phase comparison for distance measurement, for example, phase comparison is performed with a signal of several MHz for distance measurement of several meters. can do.
At this time, by changing the setting value M of the 1 / M divider and the setting value M of the 1 / M divider that the PLL of the first frequency converter should have to a desired value, the measurement object The distance range can be changed. This is a request resulting from the fact that the phase difference (distance) exceeding this is indistinguishable from a smaller phase difference (distance) because the phase-comparable range is 0 to 360 degrees.

In the application of the present invention, when a local oscillator (LO) and a mixer (mixer, multiplier) are used for demodulation, the data signals (D ₂ , D _R ) are not affected by the phase of the local oscillator (LO). is required. Since a change in amplitude is assumed due to a multipath or a barrier between the first and second transceivers, phase and frequency modulation are more suitable than modulation and demodulation of ASK. Further, PLL is also used when changing the frequency so that no phase change occurs during transmission and reception, and synchronous demodulation is performed during demodulation. Further, the modem also has a normal communication function. After the ID is confirmed by communication between the first transmitter / receiver (reader) and the second transmitter / receiver (tag), the operation shifts to a distance measuring operation.
The present invention can be used for detecting the position of an article indoors, measuring a distance between a car and a pedestrian, and measuring a distance between vehicles.

The data signal is preferably a rectangular wave. However, a data signal having an arbitrary waveform can be used as long as the phase difference can be detected. The modulation method is arbitrary, but differential modulation / demodulation is facilitated by phase modulation (PSK). BPSK and QPSK are particularly preferable. Any known technique can be employed as a carrier wave recovery method for synchronous detection. For example, an n multiplication method, an inverse modulation method, and a Costas loop can be adopted for n-phase PSK. Any known technique can be employed when modulation / demodulation is performed by FM modulation / demodulation. For example, quadrature detection or PLL detection can be used. The present invention can be implemented even if amplitude modulation is employed.
In the following description, in order to use many commercially available QPSKk synchronous demodulation ICs (orthogonal demodulator), description is made with demodulation by Costas loop, which is a QPSK synchronous demodulation system. Further, when the in-phase component and the quadrature component are modulated with the same signal, the modulation / demodulation by BPSK is substantially the same.

For distance measurement in the range of about 1 to 10 m, for example, the carrier is set to several tens of MHz to ₁ GHz, the frequency f ₁ / MN of the data signal _DT is set to tens of kHz or less, and the phase comparison signal has a frequency f ₁ / N of 1 It should be about tens of MHz. Actually, one wavelength of 5 (kHz) is 60 (km), and the time difference (phase difference) between the two round trips of 10 (m) is as small as 0.06 (deg). For example, if M = 1000, the phase difference can be compared with a signal having a frequency of 5 (MHz), and the phase difference is 60 (deg), which is output as a numerical value that is not lost in digital calculation. This is a duplex system using the 1216 MHz band and the 1252 MHz band in ARIB STD-T67 “No equipment for specified low power radio station telemeters, telecontrol and data transmission”, and the occupied frequency bandwidth is restricted to 16 kHz or less. It matches.

  Specific examples are shown below, but the present invention is not limited thereto. Each block diagram shows important components. For example, it is naturally included in the present invention to add a band-pass filter (BPF) or an amplifier such as AGC at a desired location.

  FIG. A is a block diagram showing a configuration of a first transceiver 1000 that constitutes a distance measuring apparatus according to a specific first embodiment of the present invention. In addition, FIG. B is a block diagram showing a configuration of the second transceiver 2000. FIG. In this embodiment, both the transmission from the first transceiver 1000 to the second transceiver 2000 and the reverse transmission from the second transceiver 2000 to the first transceiver 1000 use the quadrature phase modulation method (QPSK). It is what is used. In the demodulation at that time, a carrier wave is reproduced by a Costas loop.

FIG. The configuration of the first transceiver 1000 shown in A is as follows. Reference signal oscillator 100, reference signal divider 106, phase comparator 11, LPF 12, VCO 13, 1 / N divider 14, 1 / M divider 15, modulator 110, duplexer 190, antenna A ₁ , synchronous demodulation 160, frequency converter 170, and phase comparator (phase difference detector) 111. The frequency converter 170 includes a phase comparator 171, an LPF 172, a VCO 173, and a 1 / M frequency divider 175, and constitutes a PLL.

FIG. The configuration of the second transceiver 2000 shown in B is as follows. Antenna A ₂ , duplexer 290, synchronous demodulator 260, frequency converter 270 and modulator 210. The frequency converter 270 includes a phase comparator 271, an LPF 272, a VCO 273, and a frequency divider 275, and constitutes a PLL.

A rectangular wave having a frequency f ₀ , which is an output of a reference signal oscillator 100 having a fixed frequency, such as a crystal oscillator, is divided by a frequency divider 106 into a rectangular wave having a frequency f ₀ / R (R is a natural number), and the phase The comparator 11, LPF 12, VCO 13, and 1 / N frequency divider 14 constitute a PLL through the second transceiver 2000 shown below. The VCO 13 has a frequency f ₁ = Nf ₀ / R (N is an integer) ) Carrier wave. The carrier wave having the frequency f ₁ = Nf ₀ / R is output from the VCO 13 to the 1 / N frequency divider 14 and the modulator 110. The output of the 1 / N frequency divider 14 is output to the 1 / M frequency divider 15 and frequency-divided to generate a transmission data signal D _T having a frequency f ₁ / MN (M is an integer). This is output to the modulator 110. The modulator 110 QPSK modulates the carrier wave having the frequency f ₁ = Nf ₀ / R with the transmission data signal D _T having the frequency f ₁ / MN. Here, the in-phase component I and the quadrature component Q are modulated with the same value. The transmission signal is transmitted from the antenna A ₁ to the second transceiver 2000 through the duplexer 190.

In the second transceiver 2000, the signal received by the antenna A ₂ is demodulated by the synchronous demodulator 260 through the duplexer 290. Here, the carrier wave is regenerated and used by the Costas loop for demodulation of QPSK. The demodulated folded data signal D ₂ having the frequency f ₁ / MN is output to the frequency converter 270 and the modulator 210. In the frequency converter 270, a carrier wave having a frequency f ₂ (≠ f ₁ ) is generated from the looped data signal D _{2 having} the frequency f ₁ / MN by a PLL. Here, f ₂ is an integral multiple of f ₁ / MN, and the frequency divider 275 performs frequency division by 1 / integer. The carrier wave having the frequency f ₂ (≠ f ₁ ) is output to the modulator 210. Thus, the modulator 210 QPSK modulates the carrier wave having the frequency f ₂ (≠ f ₁ ) with the folded data signal D ₂ having the frequency f ₁ / MN. Here, the in-phase component I and the quadrature component Q are modulated with the same value. The transmission signal is transmitted from the antenna A ₂ to the first transceiver 1000 via the duplexer 290.

Next, in the first transmitter / receiver 1000, the signal received by the antenna A ₁ is demodulated by the synchronous demodulator 160 through the duplexer 190. Here, the carrier wave is regenerated and used by the Costas loop for demodulation of QPSK. Received data signal D _R of the demodulated, the frequency f ₁ / MN are outputted to the frequency converter 170. In the frequency converter 170, from the received data signal D _R of the frequency f ₁ / MN, the PLL, the phase comparison signal of a frequency f ₁ / N is generated and output to the phase comparator 11.

Thus, the PLL for setting the output of the VCO 13 to the frequency f ₁ = Nf ₀ / R is not only the phase comparator 11, the LPF 12, the VCO 13, and the ₁ / N frequency divider 14, but also the 1 / M frequency divider 15. After the data signal of frequency f ₁ / MN is obtained, the signal is subjected to modulation / demodulation twice, and is converted to a phase comparison signal of frequency f ₁ / N by the frequency converter 170, and then the frequency f ₀ output from the frequency divider 106 is obtained. / R reference signal and phase are locked.

Received data signal D _R of the frequency f ₁ / MN demodulated by the synchronous demodulator 160, than the 1 / M frequency divider 15 transmitted data signal D _T of the output frequency f ₁ / MN, the phase is delayed by Yes. That is, when the first transmitter / receiver 1000 and the second transmitter / receiver 2000 are separated from each other by a distance L, the data signal propagates through the distance 2L by bidirectional communication. Therefore, the time delay Δt is Δt = 2L / c. In the present invention, the phase comparator 111 compares f ₁ / N output from the 1 / N frequency divider 14 and the output of the frequency converter 170 and the signal of the frequency f ₀ / R output from the locked frequency divider 106. For example, and output in units of deg. Therefore, if the time delay Δt is smaller than N / f ₁ which is one cycle of the signal compared by the phase comparator 111, it can be detected as a phase delay (measurable distance L range). On the other hand, in terms of the accuracy of Δt, the accuracy is finer than one wavelength of the first and second carrier waves. In general, it is considered that the first and second carrier waves have an accuracy of about a quarter wavelength.

The first transceiver 1000 performs bidirectional communication with the second transceiver 2000. Transmission from the first transceiver 1000 to the second transceiver 2000 is a carrier wave of frequency f ₁ , and reverse transmission from the second transceiver 2000 to the first transceiver 1000 is frequency f ₂ (≠ f ₁ ). There is no interference because it is carried out by the carrier wave. Moreover, since they are QPSK modulated with a data signal, a strong baseband filter can be inserted, and the phase comparison of the data signal is easy even if the communication environment is bad. Because it is resistant to noise, it is easy to use even in places with relatively poor radio wave environments such as factories. Although the modulation circuit uses a mixer, all the signals input to the mixer are “synchronized” with the output from the VCO 13 so that an indefinite phase does not enter. Demodulation is quadrature demodulation using the Costas method and is synchronous detection. For this reason, an indefinite phase does not enter. After demodulating, the first transmitter / receiver up-converts to the phase comparison frequency using the PLL. Since the PLL is used, an indefinite phase does not enter at the time of the frequency conversion.
Thus, in the present invention, since the phase of the data signal is not affected at all by using the mixer, a highly accurate phase difference can be detected, and a highly accurate distance measurement can be performed.
In the present invention, the measurable distance can be freely changed by changing the setting of each frequency divider.

  The carrier wave and data signal input to the modulators of the first and second transceivers and the output of the data signal from the demodulator, the other carrier wave and data signal input and the data signal output are switched, FIG. A distance measuring device to which a communication function is added may be configured by sharing the modem, the duplexer, and the antenna with other communication devices. When the communication function is provided, first, the tag for distance measurement can be determined by the communication function.

1. 1A is a block diagram showing a configuration of a first transceiver 1000 constituting a distance measuring apparatus according to a specific embodiment of the present invention. B is a block diagram showing a configuration of the second transceiver 2000. FIG.

Explanation of symbols

1000: first transceiver 2000: second transceiver 100: oscillator (frequency fixed)
11, 111, 171, 271: Phase comparator 12, 172, 272: Low-pass filter (LPF, integrator)
13, 173, 273: Voltage controlled oscillator (VCO)
14, 15, 106, 175, 275: Frequency divider 110, 210: Modulator 160, 260: Synchronous demodulator 170, 270: Frequency conversion circuit (frequency conversion unit)
190, 290: duplexer A ₁ , A ₂ : antenna

Claims (4)

A distance measuring device comprising a first transceiver (1000) and a second transceiver (2000),
The first transceiver (1000)
Reference signal oscillators (100 and 106) for generating a reference signal having a frequency f ₀ / R (R is a natural number);
A phase comparator (11) in which one of the two inputs is the reference signal;
An integrator or low-pass filter (12) to which the output of the phase comparator (11) is input;
A voltage controlled oscillator (13) for generating a carrier of frequency f ₁ = Nf ₀ / R based on the output of the integrator or low pass filter (12);
1 / N frequency divider (N is an integer greater than or equal to 2) for generating a signal of frequency f ₁ / N = f ₀ / R from the carrier wave of frequency f ₁ = Nf ₀ / R output from the voltage controlled oscillator (13) ) (14)
Based on the output of the 1 / N frequency divider (14), a 1 / M frequency divider (15) that generates a transmission data signal D _T of frequency f ₁ / MN = f ₀ / MR (M is an integer of 1000 or more). )When,
A first modulator (110) for modulating the carrier wave of the frequency f ₁ = Nf ₀ / R with a transmission data signal D _T ;
Received from the second transceiver (2000), from the received signal obtained by modulating a carrier wave of frequency f ₂ (≠ f _1), the received data signal D _R of the frequency _{f 1 / MN = f 0 /} MR by synchronous demodulation A first synchronous demodulator (160) for demodulating;
First frequency comprising a PLL for generating a signal of the output frequency f ₁ / MN = f ₀ / frequencies from the received data signal D _R of _{MR f 1 / N = f 0} / R of the first synchronous demodulator (160) A converter (170),
The second transceiver (2000)
Second synchronization for demodulating the folded data signal D ₂ of frequency f ₁ / MN = f ₀ / MR by synchronous demodulation from the received signal obtained by modulating the carrier wave of frequency f ₁ received from the first transceiver (1000). A demodulator (260);
It consists of a PLL that generates a carrier wave of frequency f ₂ (≠ f ₁ ) that has been frequency-converted from the aliasing data signal D _{2 of} frequency f ₁ / MN = f ₀ / MR output from the second synchronous demodulator (260). A second frequency converter (270);
A second modulator (210) for modulating the carrier wave of the frequency f ₂ (≠ f ₁ ) with the folded data signal D ₂ ;
The other of the two inputs of the phase comparator (11) is the output of the first frequency converter (170),
The phase comparator (11), the integrator or low-pass filter (12), the voltage-controlled oscillator (13), and the 1 / N frequency divider (14) are transmitted data signals D of the first transceiver. _T, via a received data signal D _R of the second transceiver of the folded data signal D ₂ and the first transceiver, the output frequency f ₁ / N = f of the first frequency converter (170) ₀ / A PLL is formed so that the phase of the R signal matches the phase of the reference signal of the frequency f ₀ / R output from the reference signal oscillator (100 and 106),
The output of the 1 / N divider (14), the reference signal of the frequency f ₀ / R output from the reference signal oscillator (100 and 106), or the frequency f ₁ output from the first frequency converter (170). A distance measuring apparatus for measuring a distance between the first transceiver and the second transceiver by detecting a phase difference with a signal of / N = f ₀ / R. The first modulator (110) and the second modulator (210) are PSK modulators or QPSK modulators,
The distance measuring apparatus according to claim 1, wherein the first synchronous demodulator (160) and the second synchronous demodulator (260) are a PSK synchronous demodulator or a QPSK synchronous demodulator. The distance measuring device according to claim 1,
Both the first modulator (110) and the second modulator (210) are FM modulators,
The distance measuring apparatus according to claim 1, wherein both the first synchronous demodulator (160) and the second synchronous demodulator (260) are replaced with FM demodulator. The distance measuring device according to any one of claims 1 to 3,
The first modulator (110), the second modulator (210), the first synchronous demodulator (160), and the second synchronous demodulator (260) switch between the above configuration and a normal communication device. A distance measuring device characterized by that.

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