JP2010071861A - Apparatus and method for detection of position information - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To determine information on the position of an object to be measured in a shorter time than before when irradiating electromagnetic waves to the object to be measured, receiving reflected waves from the object to be measured, processing signals, and determining information on the position of the object to be measured. <P>SOLUTION: First coded sequence signals having a coded signal value in which a signal prior to a shift and a signal after the shift intersect with each other approximately at right angles by the shift in the bit direction bit by bit is used as signals of the electromagnetic waves to be irradiated. At this time, every time a second coded modulated signal acquired by shifting a first coded modulated signal in the bit direction is shifted by one bit, the values of a correlation function with reflected signals are computed. Information on the position of the object to be measured is determined on the basis of results of the computation. The upper bound of a measuring range of the object to be measured is set to determine an upper bound value of the amount of shift of the second coded sequence signal according to the upper bound. When the amount of shift of the second coded sequence signal exceeds the upper bound value, the computation of the correlation function is completed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a position information detection apparatus and a position information detection method for acquiring position information of a measurement object by irradiating the measurement object with an electromagnetic wave and receiving a reflected wave from the measurement object.

Radar devices are generally used for information exploration of underground reserves, understanding of underground information, or inspection and diagnosis of concrete structures. Various radar devices using laser light have also been proposed.
In the following Patent Document 1, a radar apparatus that performs distance analysis of a measurement object using a PN code is proposed.

  That is, in this patent document, a radio wave whose band is spread by a pseudo noise signal such as a PN code is transmitted, a reflected wave from an object based on the radio wave is received, and the received signal is despread by the pseudo noise signal. The radar apparatus converts the frequency of the despread received signal into a signal having a predetermined frequency, and measures the speed of the object and measures the distance to the object based on the frequency-converted signal. At this time, information on the distance to the measurement object is calculated using a correlation function of a pseudo noise signal such as a PN code.

JP-A-10-153654

In calculating such distance information, when obtaining the delay time using a pseudo-noise signal, it is necessary to increase the signal size for one period of the pseudo-noise signal in order to improve the signal-to-noise ratio of the signal. is there.
However, when the size of one period of the pseudo noise signal is increased, there is a problem that it takes a long time to obtain the delay time, and quick distance analysis cannot be performed. For example, in the distance analysis, when calculating the correlation function between the transmitted pseudo noise signal and the received signal, the distance analysis is performed in order to calculate a correlation function having a delay time corresponding to one cycle of the transmitted pseudo noise signal. It cannot be done in a short time.

  Therefore, the present invention receives the reflected wave from the measurement object by irradiating the measurement object with electromagnetic waves, performs signal processing, and obtains the position information of the measurement object. It is an object of the present invention to provide a position information detection device and a position information detection method capable of obtaining a calculation result in a shorter time than a conventional device.

In order to achieve the above object, the present invention provides a position information detection apparatus that receives a reflected wave from a measurement object by irradiating the measurement object with electromagnetic waves, performs signal processing, and obtains position information of the measurement object. It is.
This position information detection device, when irradiating an electromagnetic wave to a measurement object, an electromagnetic wave emitting unit for emitting an electromagnetic wave of a predetermined signal by a baseband method,
A receiving unit that receives a reflected wave from a measurement object irradiated with an electromagnetic wave and outputs a reflected signal; and
The predetermined signal is a signal whose signal value is encoded, and is configured so that the signal before the shift and the signal after the shift are substantially orthogonal to each other by shifting in the bit direction in the bit unit. A signal generator for generating a first encoded sequence signal having a signal length of
A value of a correlation function between the first encoded sequence signal and the reflected signal by shifting the second encoded sequence signal, which is a signal shifted by 1 bit or more bitwise in the bit direction, bit by bit. And a signal processing / calculation unit for obtaining position information of the measurement object based on the calculation result;
A condition setting unit for setting the upper limit of the measurement range of the measurement object,
The signal processing / arithmetic unit determines an upper limit value of the shift amount of the second encoded sequence signal in accordance with the upper limit of the measurement range of the set measurement object, and the shift amount of the second encoded sequence signal When the value exceeds the upper limit value, the calculation of the correlation function is terminated.

At this time, in order to obtain a correlation function between the reflected signal and the second encoded sequence signal, the signal generation unit repeatedly generates the first encoded sequence signal, and the electromagnetic wave emission unit repeatedly generates It is preferable to irradiate the electromagnetic wave of the first encoded series signal.
For example, when the correlation function forms a peak, the signal processing / arithmetic unit calculates the amount of shift between the second encoded sequence signal at the peak and the data of the second encoded sequence signal. The position of the measurement object is obtained using the time interval.

The first coded sequence signal is preferably a signal using a PN code.
The measurement object is inside a substance such as concrete or underground, and the position information is the depth of the measurement object from the material surface.

Furthermore, the present invention provides a position information detection method for obtaining position information of a measurement object by receiving a reflected wave from the measurement object by irradiating the measurement object with electromagnetic waves and performing signal processing.
In this method, when irradiating an electromagnetic wave to a measurement object, the electromagnetic wave of the first encoded series signal whose signal value is encoded with a predetermined length is emitted toward the measurement object by a baseband method; ,
Receiving a reflected wave from a measurement object irradiated with an electromagnetic wave and outputting a reflected signal;
A value of a correlation function between the first encoded sequence signal and the reflected signal by shifting the second encoded sequence signal, which is a signal shifted by 1 bit or more bitwise in the bit direction, bit by bit. Calculating the position information of the measurement object based on the calculation result;
Setting the upper limit of the measurement range of the measurement object according to the operator's input instruction,
The first encoded sequence signal is configured so that the signal before the shift and the signal after the shift are substantially orthogonal to each other by shifting in the bit direction in the bit unit.
In the step of obtaining the position information, an upper limit value of the shift amount of the second encoded sequence signal is determined in accordance with the upper limit of the set measurement range of the measurement object, and the shift amount of the second encoded sequence signal is determined. When the value exceeds the upper limit value, the calculation of the correlation function is terminated.

  In the present invention, the first encoded sequence signal having substantially orthogonality is used as the signal transmitted by the electromagnetic wave to be irradiated. At this time, the second encoded sequence signal, which is a signal obtained by shifting the first encoded sequence signal in the bit direction by 1 bit or more in bit units, is shifted one bit at a time, so that the correlation function with the reflected signal is obtained. Is calculated. For this reason, since the correlation function shows a value close to 0 in a region other than the peak generated by the reflected signal of the electromagnetic wave reflected by the measurement object, the calculation accuracy of the position information is high. At that time, the upper limit of the measurement range of the measurement object is set, the upper limit value of the shift amount of the second encoded sequence signal is determined according to the upper limit, and the shift amount of the second encoded sequence signal is set to the upper limit value. When the value exceeds, the calculation of the correlation function is terminated. For this reason, since the correlation function in the range where the shift amount is larger than the upper limit value which is unnecessary information of the correlation function is not calculated, the position information of the measurement object can be obtained in a short time.

  Hereinafter, a position information acquisition device and a position information detection method of the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.

FIG. 1 is an external view of a radar apparatus (hereinafter referred to as an apparatus) 10 which is an embodiment of a position information acquisition apparatus of the present invention.
The apparatus 10 uses the reflection signal of the measurement object X obtained by receiving the reflected wave from the measurement object X among the electromagnetic waves irradiated to the measurement object X, and the position in the depth direction to the measurement object X. It is a device that seeks information.

The apparatus 10 includes a radar main body 12 and an arithmetic device (computer) 14.
The radar main body 12 includes a transmitting antenna unit (electromagnetic wave emitting unit) 16, a receiving antenna unit (receiving unit) 18, an oscillator (signal generating unit) 20, amplifiers 22, 24, 26, and 28, an RF switch 30, 32, an RF mixer 36, low-pass filters 38 and 40, and an AD converter 42. The amplifiers 24, 26, 28, the mixer 36, the low-pass filters 38, 40, and the AD converter 42 form the signal processing unit 13.

The transmission antenna unit 16 includes a plurality of transmission antennas 16a, and each transmission antenna 16a irradiates an electromagnetic wave of a predetermined signal toward the measurement object X. The plurality of transmission antennas 16a are provided in parallel to obtain a distribution related to the position of the measurement object X.
Similarly to the transmission antenna unit 16, the reception antenna unit 18 includes a plurality of reception antennas 18a, and each reception antenna 18a is provided to receive a reflected wave from the measurement object X. The plurality of receiving antennas 18a are provided in parallel to detect the shape of the measurement object X.

  The transmission antenna unit 16 and the reception antenna unit 18 are provided with RF switches 30 and 32, respectively. The RF switches 30 and 32 are used to select and switch an antenna to be transmitted / received from the plurality of transmission antennas 16a and reception antennas 18a in accordance with a control signal from the oscillator 20.

The oscillator 20 generates a predetermined encoded sequence signal, and supplies the encoded sequence signal directly to the transmission antenna unit 16 via the amplifier 22 without being modulated using a carrier wave. That is, it is configured to emit an electromagnetic wave of an encoded sequence signal by a baseband method.
The oscillator 20 repeatedly generates an encoded sequence signal (first encoded sequence signal) supplied to the amplifier 22 and an encoded sequence signal (second encoded sequence signal) supplied to the amplifier 24. At this time, the encoded sequence signal supplied to the amplifier 24 is generated without delay (with no delay) with respect to the generation timing of the encoded sequence signal supplied to the amplifier 22. Each time a signal is generated, the signal is delayed by a certain time increment. The generation of the encoded sequence signal ends when the delay time or the delay shift amount on the data point of the encoded sequence signal exceeds a set upper limit value, as will be described later. Thereafter, the transmission antenna 16 a and the reception antenna 18 a on which the transmission antenna unit 16 and the reception antenna unit 18 operate are changed by the RF switches 30 and 32. After this change, the generation of the coded sequence signal described above is repeated again from the above-described state of zero delay. In addition, as the encoded sequence signal, the signal value is encoded with a predetermined length, and the signal before the shift and the signal after the shift are configured to be substantially orthogonal to each other by shifting in bit units in the bit direction. A signal is used. The bit direction refers to the arrangement direction of signal values. As such an encoded sequence signal, for example, a PN encoded sequence signal is preferably used. The PN encoded sequence signal is preferably a signal using an M-sequence or Gold sequence code, and the M-sequence is particularly preferable in terms of correlation characteristics described later.
In the M series, the oscillator 20 has a shift register code generator, which is an m-stage (m is a natural number) shift register and a logical combination of the states of each stage of the shift register. The signal length L is represented by 2 ^m −1 when the signal is composed of a logic circuit that feeds back to the input of the shift register. The Gold sequence is obtained by adding two M sequences in synchronization for each bit. Therefore, the phase relationship between the two code generators is invariant, and the length of the generated sequence is the same as the length of the original sequence, but does not become an M sequence.

The PN encoded sequence signal is a 1-bit signal having a value of 0 and 1, and the value of the autocorrelation function that can be shifted by the bit unit in the bit direction is 0 or -1 / n (n is a sequence code described later) Signal).
For example, the PN encoded sequence signal is a signal generated using data of a PN sequence code created as follows.
The order k = 5, the length of the code sequence n = 31, the coefficients h ₁ = 1, h ₂ = 1, h ₃ = 0, h ₄ = 1, h ₅ = 1, and the initial values a ₀ = 1, a _{When 1} = 1, a ₂ = 0, a ₃ = 1, and a ₄ = 0, the PN sequence code C = {a _k } (k is a natural number) is uniquely expressed by the recursion formula shown in the following formula (1). Can be sought.

Further, a reference encoded sequence signal is generated using a sequence code C = {a ₀ , a ₁ , a ₂ ,..., A _n-1 }, and this sequence code C is further converted into q1 bits, bits An encoded sequence signal is generated using a sequence code T _q1 · C bit-shifted in the direction (T _q1 is an operator that bit-shifts q1 bits in the bit direction). Here, the sequence code T _q1 · C is {a _q1 , a _{q1 + 1} , a _{q1 + 2} ,..., A _{q1 + N−1} }. Furthermore, a coded sequence signal is generated using a sequence code T _q2 · C obtained by shifting the sequence code C by q2 bits (for example, q2 = 2 × q1) and bit-shifting in the bit direction.
Since the sequence codes C, T _q1 · C and T _q2 · C used to generate this encoded sequence signal have characteristics orthogonal to each other, the generated encoded sequence signals also have characteristics orthogonal to each other.

More specifically, a sequence code of length n is C = {b ₀ , b ₁ , b ₂ ,..., B _n-1 }, and a sequence code in which the operator T _{q is applied} to the sequence code C. C ′ = T _q · C, that is, C ′ = {b _q , b _{q + 1} , b _{q + 2} ,..., B _{q + n−1} }, and between the sequence codes C and C ′ The correlation function R _{cc ′} (q) is defined as the following formula (2). Here, N _A is a number in which the values of the term b _i and the term b _{q + i} (i is an integer of 0 to n−1) in the sequence code match, and N _D is the term b _i and the term in the sequence code. b _{q + i is} the number of mismatches. The sum of N _A and N _D is the sequence code length n (N _A + N _D = n). Here, i and q + i are considered as mod (n).

In the PN encoded sequence, the result of adding two sequences by mod (2) for each term has a property of becoming a PN sequence code obtained by cyclically shifting the original PN sequence code, and the value of the PN sequence code is 0. Since the number is one less than the number where the value is 1, N _A −N _D = −1. Accordingly, the values shown in the following formulas (3) and (4) in the PN sequence code are shown.

From the above equation (3), when the bit shift amount is 0, that is, q = 0 (mod (n)), the value of R _{cc ′} (q) is 1 as shown in equation (3), and has autocorrelation. On the other hand, when the bit shift amount is not 0, that is, q ≠ 0 (mod (n)), R _{cc ′} (q) is − (1 / n) as shown in Expression (4). Here, by increasing the sequence code length n, the value of R _{cc ′} (q) (q ≠ 0) approaches zero.
That is, it can be said that sequence codes C and C ′ have autocorrelation and substantially orthogonality.
A PN coded sequence signal is a time series signal with such PN sequence code values of 0 and 1.
The oscillator 20 generates such a PN encoded sequence signal.
FIG. 2 is a diagram illustrating an example of a PN coded sequence signal.

In order to increase the position resolution of the measurement object X of the laser apparatus 10, it is necessary to extremely narrow the time interval Δt between the data of the encoded sequence signals. That is, it is necessary to reduce the time width for shifting the PN coded sequence signal by 1 bit. For this reason, since the oscillator 20 needs to oscillate a high-speed encoded sequence signal, as shown in FIG. 3, an FPGA (Field Programmable Gate Array) 46, parallel / serial converters 48 and 50, and synchronization signal division. It is preferable to use the devices 52 and 54 and the clock signal generator 56.
The reason why the parallel / serial converters 48 and 50 are used is to speed up the encoded sequence signal. The clock signal generator 56 is used for controlling the synchronization or delay time of two encoded series signals generated as serial signals of the parallel / serial converters 48 and 50 and sent to the amplifier 22 and the amplifier 24. is there. The synchronization or delay time is controlled by creating a correlation function with the reflected signal from the receiving antenna unit 18 by mixing the encoded sequence signal sent to the amplifier 24 with a mixer 36 described later. It is to do.
The oscillator 20 repeatedly generates an encoded sequence signal as an electromagnetic wave transmission signal in accordance with a pulse signal from the arithmetic device (computer) 14 or a pulse signal from a control device (not shown).

The amplifiers 22 and 24 amplify the encoded sequence signal obtained by the oscillator 20. If the signal level of the encoded sequence signal is sufficient, the amplifiers 22 and 24 may not be provided.
The RF switch 30 is used to emit electromagnetic waves by changing the transmission position of the transmission antenna 16a in accordance with a signal from the oscillator 20 in order to obtain information on the position of the measurement object X as a distribution.
The RF switch 32 changes the reception position of the reception antenna 18a in accordance with a signal from the oscillator 20 or a signal from a control device (not shown) in order to obtain information on the position of the measurement object X as a distribution. Used to receive.
The amplifier 26 amplifies the reflected signal obtained by the RF switch 32.

The mixer 36 performs a mixing process of the reflected signal supplied through the amplifier 26 having the information of the encoded sequence signal and the encoded sequence signal repeatedly generated with delay by the oscillator 20, and the mixed signal is obtained. Generate.
The encoded sequence signal supplied to the mixer 36 is repeatedly generated by the oscillator 20, and the generated timing is the time interval Δt between the encoded sequence signal data, that is, one bit of the encoded sequence signal. , Shifted in the bit direction. The delay due to the shift at this time is a delay based on the generation timing of the encoded sequence signal supplied to the transmission antenna unit 16.
In the mixing process, a (t + Δ) × b (t) is calculated when the delayed encoded sequence signal is a (t + Δ) and the reflected signal is b (t). Here, Δ is a delay time, and Δ = k · Δt (k is a natural number and represents a shift amount of 1 bit on the data point).
The correlation calculation by the mixing process can be performed by a computer without using the mixer 36. In this case, the output signals of the amplifiers 24 and 26 are directly captured by a computer, and the mixer 36, the low-pass filters 38 and 40, and the amplifier 28 are unnecessary.

The low-pass filter 38 removes the high-frequency component signal component from the generated mixed signal, with the frequency set according to the encoded sequence signal as a cutoff frequency, and passes the low-frequency component signal. The arithmetic unit 14 integrates the low-frequency component signal for one period of the encoded sequence signal in synchronization with the generation timing of the encoded sequence signal repeatedly generated by the oscillator 20. Thereby, the value of the correlation function in the delay time Δ can be obtained. By sequentially changing the delay time Δ, a correlation function can be obtained.
The amplifier 28 amplifies the low frequency component signal. The low-pass filter 40 removes noise components contained in the low-frequency component signal by amplification.
The AD converter 42 converts the low-frequency component signal into a digital signal and supplies it to the arithmetic unit 14 which is a computer.

The computing device 14 includes a condition setting unit 44 and a position information calculation unit 45. The computing device 14, which is a computer, manages and controls the operation of each function of the radar main body 12, and calculates the position of the measurement object X using the signal supplied from the AD converter 42. Further, a pulse signal for instructing the generator 20 to generate the encoded sequence signal is provided, and an upper limit of the delay time Δ for delaying the generation timing of the encoded sequence signal is determined.
The condition setting unit 44 and the position information calculation unit 45 are configured by modules formed by executing software in a computer that is the computing device 14.
The condition setting unit 44 determines the position where the measurement object X is located, the upper limit (the farthest in the depth direction), specifically, the position from the radar body 12 to the measurement target X in the electromagnetic wave emission direction. The upper limit value of the depth information is set by an operator inputting an instruction using a mouse or a keyboard (not shown). The upper limit value of the delay time Δ is determined from the set upper limit value of the depth information.
Specifically, when the upper limit value of the depth information to be measured is input in the condition setting unit 44, the upper limit value of the delay time Δ is obtained by dividing the upper limit value of the depth information by the propagation speed of the electromagnetic wave and doubling it. Is set. Since the time interval Δt between the encoded sequence signal data is determined, the shift amount in the bit direction, that is, the upper limit of the shift amount on the data point is obtained by dividing the delay time Δ by the time interval Δt between the data. The value is determined. This upper limit value is sent to the oscillator 20 and used for controlling the delay time Δ when generating the encoded sequence signal.

The position information calculation unit 45 obtains position information of the measurement object X from the correlation function calculation result.
The position information calculation unit 45 is supplied via the AD converter 42 for a time corresponding to one cycle of the encoded sequence signal whenever the delay time Δ of the encoded sequence signal generated by the oscillator 20 increases. The position information of the measuring object X is obtained using the signal value.

FIG. 4 is a diagram illustrating an example of a correlation function result obtained by the position information calculation unit 45 with the delay time Δ on the horizontal axis. In this example, since the upper limit value of the delay time Δ or the upper limit value of the shift amount is not set, the correlation function is calculated by extending the delay time Δ to 20 nanoseconds corresponding to the cycle of the encoded sequence signal. .
Since the correlation function shown in FIG. 4 is a result of mixing the amplified encoded sequence signal and the amplified reflected signal, the vertical axis of the correlation function is a unit of the voltage of the reflected signal. Here, the value of the correlation function is maximum at the peak A in the figure. On both sides of this peak A, overshoot occurs due to the characteristics of the receiving antenna 18a and the like, and the waveform forms the bottom.
In the results of the correlation function shown in FIG. 4, when the delay time in the peak A and delta _1, a half of the value obtained by multiplying the propagation speed of an electromagnetic wave to the delay time delta _1, the distance from the radar device 10 to the measurement object X The position information is obtained.

  As described above, the position information calculation unit 45 can obtain the position information of the measurement object X. When the shift amount of the delay time Δ exceeds the upper limit value of the set shift amount, the oscillator 20 Since the generation of the encoded sequence signal is finished, the mixing process in the mixer 36 is stopped. The reason why the calculation of the correlation function is terminated in accordance with the set upper limit value is that a signal beyond a desired distance is unnecessary and time required for unnecessary signal processing is eliminated.

FIG. 5 shows an example of the calculation result of the autocorrelation function of the PN encoded sequence signal. The correlation function shown in FIG. 4 is a function indicating the correlation between the reflected signal that is a reflected wave signal of the electromagnetic wave of the PN encoded sequence signal and the PN encoded sequence signal, and thus the reflected signal is the PN encoded sequence signal. Contains information. Therefore, the correlation function shown in FIG. 4 is an autocorrelation function as shown in FIG. 5 if the circuit bandwidth is infinite. That is, the waveform shown in FIG. 5 can be said to be an ideal waveform of the waveform shown in FIG. At this time, the value of peak A is 1 (high level voltage value), and at other positions, −1 / n (n is the number of data in one cycle of the encoded sequence signal). Therefore, in order to increase the S / N ratio of the correlation function, as can be seen from the ideal waveform shown in FIG. 5, the value is -1 / n in the noise region other than the peak A in the correlation function. In other words, it is necessary to achieve orthogonality (substantially orthogonal). For this purpose, it is necessary to increase the number of data n in one cycle of the encoded sequence signal. However, by increasing the number of data n, the time T (= n · Δt) corresponding to one cycle increases, and it takes a lot of calculation time to calculate the correlation function in the range of 0 to T delay time. . For this reason, as described above, the calculation of the correlation function ends according to the upper limit value of the shift amount set by the upper limit of the measurement range of the measurement object X. And since the peak A which shows the positional information on the measuring object X exists in the range of the shift amount within the upper limit, the position of the measuring object X can be calculated from the correlation function.
As described above, the position information calculation unit 45 can improve the SN ratio of the correlation function and can calculate the correlation function including the position information of the measurement object X in a short calculation time. The calculated correlation function is output to a display or printer (not shown).

The above is the description of the configuration of the radar apparatus 10.
In such a radar apparatus 10, an electromagnetic wave of an encoded sequence signal such as a PN encoded sequence signal is emitted from the transmission antenna unit 16 toward the measurement target X by a baseband transmission method.
Next, a reflected wave from the measurement object X irradiated with the electromagnetic wave is received by the antenna receiver 18 and a reflected signal is output.
In the signal processing unit 13 or the arithmetic unit 14, the encoded sequence signal (second encoded signal) is a signal obtained by shifting the encoded sequence signal (first encoded sequence signal) of the electromagnetic wave by one bit or more in the bit direction. Each time one bit is shifted by 1 bit, the mixer 36 performs a mixing process as a reference signal (LO). Thus, the value of the correlation function is calculated by performing a mixing process with the reflected signal (RF). Based on the calculated function, position information of the measurement object X is obtained. The encoded sequence signal used here is a signal in which a signal value, for example, a 1-bit signal value is encoded with a predetermined length, and is shifted in a bit unit in the bit direction so that the signal before the shift and the signal after the shift Are signals that are substantially orthogonal to each other.

Since the signal before the shift and the signal after the shift are substantially orthogonal to each other as the encoded sequence signal, when the correlation function with the reflected signal is obtained, the value is approximately 0 when there is no correlation. Become. For this reason, the peak position of the correlation function indicating the position information of the measurement object X is clearly formed. Therefore, the position information of the measurement object X can be obtained with high accuracy.
A part of the electromagnetic wave irradiated from the transmitting antenna 16a is directly received by the receiving antenna 18a without being reflected. The position information of the measurement object X is corrected using the signal by this reception as a reference in the position information. Ask.

  On the other hand, the condition setting unit 44 sets the upper limit of the measurement range of the measurement object X according to the input instruction from the operator before the measurement. The upper limit value of the delay time of the encoded sequence signal or the upper limit value of the shift amount is determined according to the set upper limit of the measurement range of the measurement object X. When the delay time or shift amount of the encoded sequence signal used as the reference signal exceeds a predetermined upper limit value, the calculation of the correlation function is terminated. For this reason, since the value of the correlation function becomes unnecessary information in a range where the shift amount is larger than the upper limit value, the correlation function is not calculated. For this reason, the position information of the measuring object X can be obtained in a short time.

  FIG. 6A shows the calculation result of the correlation function obtained when the measurement object X is a reinforcing bar embedded in concrete and the electromagnetic wave of the PN encoded sequence signal is irradiated toward the concrete in which the reinforcing bar is embedded. It is. Δt in the PN encoded sequence signal was 0.1 (nanosecond), and the number of data n of the PN encoded sequence signal was 1024. The horizontal axis in FIG. 6A represents the shift amount on the data point as a unit. Here, the upper limit value of the shift amount on the data point is set to 128. That is, in FIG. 6A, the value of the correlation function after the data point 128 is not calculated. Since the position of the reinforcing bar embedded in the concrete is roughly known, referring to this approximate position, the operator inputs the upper limit of the measurement range in the depth direction in the concrete, so that the upper limit value of the shift amount is set. Can be determined. In addition, the electromagnetic wave is greatly attenuated inside a substance such as concrete or in the ground, and the reflected wave at a deep point hardly returns. The measurement range inside a substance such as concrete is several centimeters to several tens of centimeters. In consideration of this attenuation, an upper limit value of a required delay time range in the correlation function can be determined, and the calculation of the correlation function can be terminated using this upper limit value.

The correlation function in FIG. 6A is inverted between positive and negative depending on the polarity of the amplifier. Accordingly, the portion forming the bottom in the figure has a peak. In FIG. 6A, peak B is due to the reflected wave signal reflected from the concrete surface, and peak C is due to the reflected wave reflected from the reinforcing bar. The reason why the peaks are formed on both sides of the peak B (bottom part) is that ringing occurs because the band is finite. Thus, even if a plurality of reflected waves are received, the plurality of reflections can be separated and identified by calculating the correlation function. From this, the delay time between peak B and peak C is obtained, and by multiplying this by the propagation speed of the electromagnetic wave, the position (depth) of the reinforcing bar, which is the measurement object X, from the concrete surface is obtained. Can do. As described above, the measurement object X is inside a substance such as concrete or underground, and the depth from the material surface can be obtained as position information of the measurement object X.
FIG. 6B is made from a correlation function obtained by using one transmission antenna 16a and one reception antenna 18a for concrete in which a reinforcing bar is embedded, as in the example shown in FIG. 6A. This is a light and shade distribution of reception results. In FIG. 6B, the position of the reinforcing bar in the depth direction relative to the position of the antenna used for measurement changes as the antenna used for measurement moves. Accordingly, as shown in FIG. 6B, the portion indicating the position of the peak B formed by the reflection of the reinforcing bar has a hyperbolic shape due to the change in the position in the lateral direction. As described above, the radar apparatus 10 can also obtain the position of the measurement object X.

  As described above, the position information acquisition apparatus and the position information detection method of the present invention have been described in detail. However, the present invention is not limited to the above-described embodiment, and various improvements and modifications can be made without departing from the gist of the present invention. Of course it is also good.

It is a schematic block diagram which shows the structure of the radar apparatus which is one Embodiment of the positional information acquisition apparatus of this invention. It is a figure which shows an example of the PN encoding series signal produced | generated with the radar apparatus shown in FIG. FIG. 2 is a block diagram illustrating an example of a configuration of an oscillator illustrated in FIG. 1. It is a figure which shows an example of the correlation function obtained with the radar apparatus shown in FIG. It is a figure which shows the autocorrelation function of a PN encoding series signal. (A) And (b) is a figure which shows the calculation result of the correlation function in the measuring object different from FIG. 4 obtained by the radar apparatus shown in FIG.

DESCRIPTION OF SYMBOLS 10 Radar apparatus 12 Radar body part 13 Signal processing part 14 Arithmetic unit 16 Transmitting antenna part 18 Receiving antenna part 20 Oscillator 22, 24, 26, 28 Amplifier 30, 32 RF switch 36, 40 RF mixer 42 AD converter 44 Condition setting part 45 position information calculation unit 46 FPGA
48, 50 Parallel-serial converter 52, 54 Sync signal divider 56 Clock signal generator

Claims (6)

A position information detection device that receives a reflected wave from a measurement object by irradiating the measurement object with electromagnetic waves, performs signal processing, and obtains position information of the measurement object,
When irradiating the object to be measured with electromagnetic waves, an electromagnetic wave emitting unit that emits electromagnetic waves of a predetermined signal by a baseband method;
A receiving unit that receives a reflected wave from a measurement object irradiated with an electromagnetic wave and outputs a reflected signal; and
The predetermined signal is a signal whose signal value is encoded, and is configured so that the signal before the shift and the signal after the shift are substantially orthogonal to each other by shifting in the bit direction in the bit unit. A signal generator for generating a first encoded sequence signal having a signal length of
A value of a correlation function between the first encoded sequence signal and the reflected signal by shifting the second encoded sequence signal, which is a signal shifted by 1 bit or more bitwise in the bit direction, bit by bit. And a signal processing / calculation unit for obtaining position information of the measurement object based on the calculation result;
A condition setting unit for setting the upper limit of the measurement range of the measurement object,
The signal processing / arithmetic unit determines an upper limit value of the shift amount of the second encoded sequence signal in accordance with the upper limit of the measurement range of the set measurement object, and the shift amount of the second encoded sequence signal When the value exceeds the upper limit value, the calculation of the correlation function is terminated.   The position information according to claim 1, wherein the signal generation unit repeatedly generates the first encoded sequence signal, and the electromagnetic wave emitting unit irradiates the electromagnetic wave of the first encoded sequence signal generated repeatedly. Detection device.   When the waveform of the correlation function forms a peak, the signal processing / arithmetic unit calculates the amount of shift between the second encoded sequence signal at the peak and the data of the second encoded sequence signal. The position information detection apparatus according to claim 1, wherein the position of the measurement object is obtained using a time interval.   The position information detection device according to claim 1, wherein the first encoded sequence signal is a signal using a PN code. The measurement object is inside the substance,
The position information detection apparatus according to claim 1, wherein the position information is a depth of the measurement object from a substance surface. A position information detection method for receiving a reflected wave from a measurement object by irradiating the measurement object with electromagnetic waves, performing signal processing, and obtaining position information of the measurement object,
When irradiating an electromagnetic wave to the measurement object, emitting the electromagnetic wave of the first encoded series signal in which the signal value is encoded with a predetermined length toward the measurement object by a baseband method;
Receiving a reflected wave from a measurement object irradiated with an electromagnetic wave and outputting a reflected signal;
A value of a correlation function between the first encoded sequence signal and the reflected signal by shifting the second encoded sequence signal, which is a signal shifted by 1 bit or more bitwise in the bit direction, bit by bit. Calculating the position information of the measurement object based on the calculation result;
Setting the upper limit of the measurement range of the measurement object according to the operator's input instruction,
The first encoded sequence signal is configured so that the signal before the shift and the signal after the shift are substantially orthogonal to each other by shifting in the bit direction in the bit unit.
In the step of obtaining the position information, an upper limit value of the shift amount of the second encoded sequence signal is determined in accordance with the upper limit of the set measurement range of the measurement object, and the shift amount of the second encoded sequence signal is determined. When the value exceeds the upper limit value, the calculation of the correlation function is terminated.