JP2007278932A - Minute movement detection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To facilitate initial setting of a minute movement detection device for detecting minute movement of an object by using a phase detector. <P>SOLUTION: A transmitting antenna 7 irradiates a movement detection object with a transmitting signal transmitted by transmitting signal generators (1-4) as a transmitting wave. A receiving antenna 8 outputs a receiving signal catching a reflection wave obtained to be reflected on the movement detection object by the transmitting wave. The phase detector 12 detects a phase difference between the transmitting wave and a receiving signal. A determination means 13 determines a movement state of the movement detection object based on a detecting signal of the phase detector 12. An initial setting means 13 controls phase switchers 14a-c so that an initial phase difference is nearest to the center of a linear region in phase detection characteristics of the phase detector 12 based on the detecting signal of the phase detector 12. The phase switchers 14a-c switch any one of a low frequency transmitting signal or a low frequency receiving signal by only a prescribed phase difference part. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a minute movement detection device that detects minute movement of an object using a microwave.

  In Patent Document 1 below, the maximum amplitude of a standing wave formed by a microwave having a predetermined wavelength (transmitted wave) and a received wave (reflected wave) obtained by reflecting the transmitted wave on a movement detection object is disclosed. A movement distance detection device that detects a minute movement of a movement detection object by detecting the movement is disclosed.

  The amplitude of the standing wave changes sinusoidally according to the position between the reception point and the movement detection object, and the movement detection target is the reception point when the reception point and transmission point of the transmission wave are fixed. When moving in a direction approaching or separating from, the amplitude of the standing wave at the reception point changes in a sine wave shape. In the movement distance detection device, the position where the amplitude of the standing wave that changes in a sine wave is maximized is tracked, and the deviation of the position from the reference position is detected as the movement amount of the movement detection object.

  However, in a standing wave that changes in a sine wave shape, the amplitude of the standing wave in the vicinity of the maximum amplitude value is slow, and an error is likely to occur in the detection of the maximum amplitude value of the standing wave. The detection error of the maximum amplitude value becomes the detection error of the minute movement amount as it is. Therefore, the conventional technique has a problem that the detection accuracy of the minute movement amount is lowered due to the detection error of the maximum amplitude value of the standing wave.

The present applicant has applied for an invention that solves the above-mentioned problems (Japanese Patent Application No. 2005-369126). The technology disclosed here detects the minute movement of the movement detection object by detecting a change in the phase difference between the transmission wave emitted from the minute movement detection device and the reflected wave reflected by the transmission signal on the movement detection object. Is detected.
JP 2000-046934 A

  By the way, the phase detector in the device of Japanese Patent Application No. 2005-369126 has a phase detection characteristic in which the voltage value of the detection signal changes in a triangular wave shape every 360 °. That is, for example, in the phase difference range of 0 to 180 °, the voltage value of the detection signal increases substantially linearly, and in the phase difference range of 180 to 360 °, the voltage value of the detection signal decreases substantially linearly. The linearity in the change in the voltage value of the detection signal is best near the center (90 ° or 270 °) of each phase difference range, and the voltage value of the detection signal changes from rising to falling. Or it is not good around 360 °. Therefore, in the vicinity of 180 ° or 360 °, there is a problem that the detection accuracy of the phase difference is lowered.

  Considering the phase detection characteristics of such a phase detector, the position of the minute movement detection device is conventionally adjusted so that the phase difference is initially set to 90 ° or 270 ° when the minute movement detection device is installed. However, this position adjustment is extremely complicated due to the topography of the installation location.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to facilitate the initial setting of a minute movement detection device that detects a minute movement of an object using a phase detector. .

  In order to solve the above problems, in the present invention, as a first means, a transmission signal generator that generates a transmission signal having a wavelength in the microwave band, and the movement detection target object is irradiated with the transmission signal as a transmission wave. Using a transmission antenna, a reception antenna that captures a reflected wave obtained by reflecting the transmission wave on an object to be detected and outputs a reception signal, a local signal generator that generates a local signal of a predetermined frequency, and a local signal Transmission signal frequency converter for frequency conversion of transmission signal to low frequency transmission signal, reception signal frequency converter for frequency conversion of reception signal to low frequency reception signal using local signal, low frequency transmission signal or low frequency reception signal Detecting a phase difference between a low-frequency transmission signal and a low-frequency reception signal at a subsequent stage of the phase switch that switches either one of the two by a predetermined phase difference A phase detector; a determination means for determining a movement state of the movement detection object based on the detection signal of the phase detector; and an initial phase difference based on the detection signal of the phase detector. And an initial setting means for controlling the phase switch so as to be closest to the center of the straight line region in the detection characteristics.

  As a second means, in the first means, the phase switch is formed by combining a plurality of signal delay means for delaying either the low-frequency transmission signal or the low-frequency reception signal by a predetermined fixed phase. The thing was adopted.

  According to the present invention, there is provided a phase switch that switches a phase of either a low-frequency transmission signal or a low-frequency reception signal by a predetermined phase difference, and the phase is switched by the initial setting means based on the detection signal of the phase detector. By controlling the detector, the initial phase difference is made closest to the center of the linear region in the phase detection characteristics of the phase detector, so the initial value of the initial phase difference is optimized regardless of the fine adjustment of the device position. Therefore, the initial setting of the minute movement detection device can be facilitated.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram of a minute movement detection apparatus according to the first embodiment. As shown in FIG. 1, the present minute movement detecting device includes a voltage controlled oscillator 1, a coupler 2, a transmission signal power distributor 3, a PLL (Phase Locked Loop) circuit 4, an attenuator 5, and a transmission signal mixer 6. , Transmitting antenna 7, receiving antenna 8, received signal mixer 9, local signal power distributor 10, local oscillator 11, phase detector 12, one-chip microcomputer 13, phase switchers 14 a, 14 b and 14 c, and amplifier 15. ing.

The voltage controlled oscillator 1 oscillates a microwave band transmission signal based on the control voltage input from the PLL circuit 4. The frequency of this transmission signal is, for example, 10.525 GHz. The coupler 2 is provided in a signal transmission path between the voltage controlled oscillator 1 and the transmission antenna 7, and outputs a part of the transmission signal output from the voltage controlled oscillator 1 to the transmission signal power distributor 3.
The transmission signal power distributor 3 distributes the transmission signal inputted from the coupler 2 to the PLL circuit 4 and the attenuator 5. The PLL circuit 4 generates the control voltage based on the transmission signal input from the transmission signal power distributor 3. The voltage controlled oscillator 1, the coupler 2, the transmission signal power distributor 3, and the PLL circuit 4 form a control loop that controls oscillation of the transmission signal in the voltage controlled oscillator 1. Equivalent to.

  The attenuator 5 is provided in a signal transmission path between the transmission signal power distributor 3 and the transmission signal mixer 6, and attenuates the transmission signal input from the transmission signal power distributor 3 by a predetermined amount. It outputs to the mixer 6 for transmission signals. The transmission signal mixer 6 converts the frequency of the transmission signal input from the attenuator 5 into a low frequency transmission signal based on the local signal input from the local signal power distributor 10, and the transmission signal frequency in the present embodiment. It corresponds to a converter.

  The transmission antenna 7 is a circularly polarized antenna that irradiates the movement detection object (for example, a wall surface of a rock, etc.) with the transmission signal as a transmission wave whose polarization plane turns right. The reception antenna 8 is a circularly polarized antenna that captures a reflected wave obtained by reflecting the transmission wave on a movement detection object (not shown) and outputs a reception signal. This reflected wave is a microwave in which the transmitted wave is reflected by the movement detection object, and thus the polarization plane is a left-turned wave opposite to the transmitted wave (turned to the right). The transmission antenna 7 and the reception antenna 8 are fixed at positions that are the same distance from the movement detection object.

The amplifier 15 amplifies the reception signal input from the reception antenna 8 and outputs the amplified signal to the reception signal mixer 9.
The reception signal mixer 9 converts the frequency of the reception signal input from the amplifier 15 into a low frequency reception signal based on the local signal input from the local signal power distributor 10, and the reception signal frequency in the present embodiment. It corresponds to a converter.
The local oscillator 11 oscillates a local signal and outputs it to the local signal power distributor 10 and corresponds to a local signal generator in the present embodiment. The frequency of this local signal is 9 GHz, for example. The local signal power distributor 10 distributes the local signal input from the local oscillator 11 to the transmission signal mixer 6 and the reception signal mixer 9.

  The phase detector 12 detects the phase difference between the low-frequency transmission signal input from the transmission signal mixer 6 and the low-frequency reception signal input from the reception signal mixer 9 and outputs the detection signal to the one-chip microcomputer 13. . This phase detector 12 has a phase detection characteristic as shown in FIG. 2, that is, a characteristic in which the detection signal increases linearly for a phase difference in the range of 0 to 180 °, and a level in the range of 180 ° to 360 °. The phase difference has a characteristic that the detection signal decreases linearly.

  When the control signal is input from the one-chip microcomputer 13A, the phase switch 14a switches the phase by 22 ° by delaying the low-frequency transmission signal. When the control signal is input from the one-chip microcomputer 13A, the phase switch 14b switches the phase by 44 ° by delaying the low-frequency transmission signal. When the control signal is input from the one-chip microcomputer 13A, the phase switch 14c switches the phase by 88 ° by delaying the low-frequency transmission signal. These phase switches 14 a, 14 b and 14 c are connected in series and are provided between the transmission signal mixer 6 and the phase detector 12.

  The one-chip microcomputer 13 corresponds to the determination means in the present embodiment, determines the movement state of the movement detection object based on the detection signal of the phase detector 12, and outputs the determination result to the outside. The one-chip microcomputer 13 includes an A / D converter that quantizes the detection signal (analog signal) described above, a storage unit that stores a predetermined determination processing program, and a detection as a digital signal output from the A / D converter. The CPU includes a central processing unit (CPU) that performs determination processing based on the determination processing program, and an output unit that outputs a determination processing result by the CPU to the outside.

  Further, the one-chip microcomputer 13 corresponds to the initial setting means in the present embodiment, and the initial phase difference is based on the detection signal of the phase detector 12, and the phase detection characteristic of the phase detector 12 (FIG. 2). The phase switchers 14a, 14b, and 14c are controlled so as to be closest to the center of the straight line region.

  Next, the operation of the main part of the minute movement detecting apparatus configured as described above will be described in detail with reference to FIG.

  In this minute movement detection device, a transmission wave having a frequency of 10.525 GHz is irradiated from the transmission antenna 7 onto the movement detection object, and this transmission wave is reflected by the movement detection object (similar to the transmission wave). Having a frequency of 10.525 GHz) is received by the receiving antenna 8. The reception timing of the reflected wave based on the transmission timing of the transmission wave is obtained by adding the time for the reflected wave to propagate from the movement detection object to the reception antenna 8 to the time for the transmission wave to propagate from the transmission antenna 7 to the movement detection object. Will be.

  That is, the phase difference between the transmission wave and the reception wave changes according to the distance between the transmission antenna 7 (reception antenna 8) and the moving detection object of the microwave (transmission wave and reception wave) having a frequency of 10.525 GHz. Will be. As shown in FIG. 3, the reflected wave 1 when the rock wall surface (movement detection object) is at position A and the reflected wave 2 when the rock wall surface is at position B have different phase differences with respect to the transmitted wave. Yes.

  Such a phase difference between the transmission wave and the reception wave is a value corresponding to the distance between the minute movement detection device and the movement detection target, and is synonymous with a phase difference between the transmission signal and the reception signal. Therefore, when the present minute movement detection device is fixedly installed so as not to change its position, it is possible to determine the movement state of the movement detection object by detecting the phase difference between the transmission signal and the reception signal.

  In the present minute movement detection device, a transmission signal having extremely high frequency stability is generated by the above-described control loop, and based on such a transmission signal, a transmission wave is irradiated from the transmission antenna 7 to the movement detection object, and a reflected wave is generated. Captured by the receiving antenna 8. The transmission signal is frequency-converted to a low-frequency transmission signal by the transmission signal mixer 6, while the reception signal is frequency-converted to a low-frequency reception signal by the reception signal mixer 9, and the low-frequency transmission signal, the low-frequency reception signal, Is detected by the phase detector 12. The low-frequency transmission signal and the low-frequency reception signal are frequency-converted by the same local signal, and therefore the phase difference is the same as the phase difference between the transmission signal and the reception signal before frequency conversion.

  In the determination processing program incorporated in the one-chip microcomputer 13, frequency information of the transmission wave (reception wave), that is, “10.525 GHz” is captured as data, and the one-chip microcomputer 13 performs phase detection based on the determination processing program. Based on the detection signal input from the detector 12, that is, the phase difference between the low-frequency transmission signal and the low-frequency reception signal and the frequency of the transmission wave (reception wave), the movement distance of the movement detection object is calculated.

In such an initial setting operation of the minute movement detection apparatus, the one-chip microcomputer 13 determines that the initial phase difference is a straight line in the phase detection characteristic (FIG. 2) of the phase detector 12 based on the detection signal of the phase detector 12. The phase switches 14a, 14b, and 14c are controlled so as to be closest to the center of the region, that is, 90 ° or 270 °.
Referring to FIG. 2 again, the phase difference characteristics of the phase detector 12 are actually poor in the vicinity of 0 °, 180 ° and 360 ° compared to the linearity of 90 ° and 270 °. In order to set a range with better linearity as a phase difference detection range, initially, the phase difference is an intermediate position of 0 to 180 ° (linear increase region) or 180 ° to 360 ° (linear decrease region), that is, It is set to approach 90 ° or 270 °.

  For example, before the initial setting, if the phase difference based on the detection signal of the phase detector 12 is about 30 °, the one-chip microcomputer 13 controls the phase switch 14a to delay the low-frequency transmission signal to adjust the phase. If the phase shifter 14b is also controlled to further delay the low-frequency transmission signal and shift the phase by 44 °, the phase difference becomes about 96 °. Thus, since the phase switchers 14a, 14b, and 14c switch phases by 22 °, 44 °, and 88 °, respectively, 0 °, 22 °, 44 °, 66 °, and 88 ° depending on the combination. , 110 °, 132 °, and 154 °, the phase can be switched.

  In this state, when the movement detection object moves minutely in the direction approaching or moving away from the minute movement detection device, the phase difference increases or decreases from the vicinity of 90 °, and the value of the detection signal of the phase detector 12 becomes Good phase difference detection accuracy can be obtained by linearly increasing or decreasing along the phase detection characteristics.

In the present embodiment, the phase of the low-frequency transmission signal is switched by the phase switches 14a, 14b, and 14c. However, the phase of the low-frequency reception signal may be switched by the phase switches 14a, 14b, and 14c. good.
In the present embodiment, three phase switchers 14a, 14b, and 14c are provided. However, the number of phase switchers is not limited to three.

It is a block diagram which shows the structure of the micro movement detection apparatus in one Embodiment of this invention. It is a characteristic view which shows the phase detection characteristic of the phase detector 12 of the micro movement detection apparatus in one Embodiment of this invention. It is a schematic diagram which shows the operation | movement principle of the micro movement detection apparatus in one Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Voltage controlled oscillator, 2 ... Coupler, 3 ... Transmission signal power divider, 4 ... PLL circuit, 5 ... Attenuator, 6 ... Transmission signal mixer (transmission signal frequency converter), 7 ... Transmission antenna, 8 ... Reception antenna 9 ... Receive signal mixer (received signal frequency converter), 10 ... Local signal power distributor, 11 ... Local oscillator (local signal generator), 12 ... Phase detector, 13 ... One-chip microcomputer (determination means, initial stage) Setting means), 14a, 14b, 14c ... phase switch, 15 ... amplifier

Claims (2)

A transmission signal generator for generating a transmission signal having a wavelength in the microwave band;
A transmission antenna that irradiates the movement detection object as a transmission wave with the transmission signal;
A receiving antenna that captures a reflected wave obtained by reflecting the transmission wave on a moving detection object and outputs a reception signal;
A local signal generator for generating a local signal of a predetermined frequency;
A transmission signal frequency converter that converts a transmission signal into a low-frequency transmission signal using a local signal;
A received signal frequency converter that converts a received signal into a low frequency received signal using a local signal; and
A phase switch that switches either a low-frequency transmission signal or a low-frequency reception signal by a predetermined phase difference;
A phase detector for detecting a phase difference between a low-frequency transmission signal and a low-frequency reception signal in a subsequent stage of the phase switch;
Determination means for determining the movement state of the movement detection object based on the detection signal of the phase detector;
Based on the detection signal of the phase detector, initial setting means for controlling the phase switch so that the initial phase difference is closest to the center of the linear region in the phase detection characteristics of the phase detector;
A minute movement detecting device comprising:   2. The minute movement detecting device according to claim 1, wherein the phase switch is formed by combining a plurality of signal delay means for delaying either one of the low-frequency transmission signal and the low-frequency reception signal by a predetermined fixed phase. .

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