JP3528580B2 - Object measuring device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an object display device for displaying the position of an object existing in a certain area on a screen through the transmission and reception of sound waves or radio waves, such as a sonar and radar, and the position and shape of the object. The present invention relates to an object measuring device.

[0002]

2. Description of the Related Art Generally, sound waves or radio waves are transmitted within a certain area such as a sonar or radar, the reflection signals from an unspecified number of objects existing within the area are received, and the position is displayed on a screen. Object display devices are known. As a specific example, there is a device by R. J. Yurick, Akira Tsuchiya: Principle of underwater acoustics: Kyoritsu Publishing: p9. The outline of the apparatus will be described with reference to FIG.

The object display device 10 is mounted on a ship and displays the position of an object existing in water. As shown in FIG. 1, a transmission device 11 that generates a signal to be transmitted, a transmission signal generated by the transmission device 11 is converted into ultrasonic waves, and the ultrasonic waves are transmitted.
A wave transmission / reception device 12, which receives a reflected wave and converts it into an electric signal,
Receiving device 1 which forms an acoustic beam by power-amplifying and digital-converting a received signal input from the transmitting / receiving device 12
3. A signal processing device 14 that performs predetermined signal processing on a received signal sequence input from the receiving device 13 and converts it into a video signal, and a display device 15 that displays the video signal input from the signal processing device 14 on a display screen. To be done. Among these, the functions of the wave transmission / reception device 12, the reception device 13, and the display device 15 will be described with reference to the drawings.

The structure of the wave receiving portion of the wave transmitting / receiving device 12 and the receiving device 13 is shown in FIG. The wave receiving portion of the wave transmitting / receiving device includes a hydrophone 21i (i = 1, ..., N), and the receiving device 13 includes a power amplifier 22, a digital converter 23, and a phasing processor 24.

The wave receiving portion of the wave transmitting / receiving device 12 is composed of N hydrophones, and outputs a reception signal received by each hydrophone to the receiving device 13.

The receiving device 13 performs power amplification and digital conversion of the received signal via the input and output to and from the power amplifier 22 and the digital converter 23 for each hydrophone, and the phasing processor 24. To form an acoustic beam. Although various methods have been conventionally used as a phasing processing method in the phasing processor 24, a delay phasing method will be described as an example here. The configuration of the phasing processor 25 that performs the delay phasing method is shown in FIG. Phaser 24
Is composed of delay devices 31ji (i = 1, ..., N, j = 1, ..., M) and taps 32ji (i = 1, ..., N, j = 0, ..., M). The phasing processor 24 operates so that the delay of the input hydrophone output becomes linear as indicated by the tap addition lines 33 and 34, so that the beam B with respect to the angle θ is changed.
Form (θ). For example, the beam B (0) in the front direction can be formed by combining the signals of the outputs of the hydrophones without delaying the tap addition line 33. If the operation is performed so that the delay of each hydrophone output becomes linear as indicated by the addition line 34, the beam B with respect to the angle θ1
(θ1) can be formed. By this operation, it is possible to radially form a certain number of beams within a certain range as shown in FIG. If this is expressed by a mathematical expression, it is expressed by the following Expression 1.

[0007]

[Equation 1]

The display device 15 displays on the display screen the received signal sequence converted into a video signal, which is input from the signal processing device 14. An example of the display screen is shown in FIG. Distance in radial direction,
The circumferential direction represents the azimuth, respectively. On the screen, the amplitude value of the received signal train is displayed in luminance. In this case, the resolution in the azimuth direction depends on the beam width formed by the receiver 13, and the smaller the beam width, the higher the azimuth resolution.

[0009]

The problem to be solved by the present invention is to provide a wave transmitting / receiving device 12 in the above object display device.
And on the display device 15.

As described above, the lateral resolution on the display screen depends on the beam width. Theoretically, in order to narrow the beam width, the aperture length of the wave receiver in the wave transmission / reception device 12 should be increased, but the size of the wave transmission / reception device 12 is physically limited. Therefore, when there is an object smaller than the beam width as shown in FIG. 6A, or when there is a region in which the beam width cannot be made narrow as shown in FIG. , It becomes difficult to specify the size of the object.

[0011]

In order to achieve the above object, according to the present invention, a means for performing a phasing process on a received signal to form an acoustic beam, and a beam or the like designated by each user from each formed beam. Means for extracting the signal sequence including the reflected signal, means for calculating the frequency spectrum of the signal sequence by performing Wigner distribution analysis on the extracted signal sequence, and the rising position and maximum position of the spectrum from the frequency spectrum And a means for calculating the fall position temporally and a means for measuring the position and shape of the object that emits the reflection signal from the calculated temporal position of each point, so that There is provided an object display device having a function of recognizing a shape with high accuracy.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The principle of the position and shape measuring method according to the present invention will be described by dividing it into a position measuring method and a shape measuring method.

First, the position measuring method will be described.

As shown in FIG. 7, each device and measurement object are arranged at the following positions on the xy plane.

Transmitter: origin, left receiver: point (-D, 0),
Right receiver: Point (D, 0) Measuring object: Point (x, y) Now, assuming that sound waves are radiated from the transmitter at time t = 0, both receivers receive the reflected wave from the measuring object. Consider the time to receive the wave. Due to the positional relationship of the transducers, when the measured object is in the first quadrant (x> 0, y> 0), the right receiver receives the reflected wave earlier than the left receiver, and conversely to the left. If the receiver receives more quickly than the right receiver, the measured object is in the second quadrant (x <0,
y> 0). If the times at which the left and right receivers receive the reflected waves are set as Tl and Tr, respectively, the following equation 2 holds for Tl and Tr.

[0016]

[Equation 2]

As shown in FIG. 7, if the distance from the origin to the measuring object is r and the angle between the azimuth of the measuring object and the y axis is θ,
From Equation 2, the position (x, y) of the measurement object is expressed by Equation 3 below.

[0018]

[Equation 3]

Now, consider a method of measuring the reception times Tl and Tr. First, as shown in FIG. 8, a method of observing the time waveforms of the left and right receivers and setting the rising times of the waveforms as Tl and Tr can be considered. However, in a sonar device that transmits sound waves into the sea, in addition to the reflected wave from the measurement object, noise and reverberation, which is the reflection from the sea surface, the seabed, and the underwater scatterers, are mixed in the received waveform, and the accurate Tl , Tr
Is difficult to measure. The same applies to a radar device that transmits radio waves into the atmosphere.

Therefore, let us consider using an instantaneous spectrum based on the Wigner distribution instead of the time waveform. Here, the instantaneous spectrum refers to the time change of the spectrum of the specific frequency component. The Wigner distribution has excellent time resolution, and the influence of noise and reverberation is smaller than that of the time waveform, so that Tl and Tr can be measured by sonar and radar devices. FIG. 9 shows an outline of the Tl and Tr measurement method using the instantaneous spectrum. The instantaneous spectrum of the transmission frequency component is obtained from the Wigner distribution of the left and right received waveforms, Tl and Tr are calculated from the peak positions thereof, and the positions are calculated by substituting into Equation 3.

Second, the shape measuring method will be described.

The relationship between the size of the measuring object and the reflected wave will be described with reference to FIG. The left side of the figure shows a small measurement object, and the right side shows a large measurement object. When the measurement object is small, the reflection point is small, so the time length of the echo becomes short, and as a result, the peak shape of the instantaneous spectrum has a sharp waveform. On the other hand, in the case of a large measurement object, it is reflected at a plurality of points on the surface of the object as shown in the figure, and the time length of the echo becomes long. Therefore, the peak shape of the instantaneous spectrum has a gentle parabolic shape as shown in the figure. Thus, the echo time length and the peak shape of the instantaneous spectrum depend on the shape of the measurement object. For the above reason, since the echo time length is not suitable for measurement, the instantaneous spectrum is applied as shown in FIG. 11 to measure the shape of the measurement object. In addition to the peak positions Tl and Tr measured during position measurement, a rising position Tsl exceeding a preset threshold,
Falling positions Tel and Te below Tsr and the threshold value
Three sets of (x, y) are calculated by measuring r and substituting it into equation 3. The shape of the measurement object is 3
It is calculated from the positional relationship of (x, y) in the set.

FIG. 1 shows the configuration of an apparatus for implementing the present invention.
2 shows. A shape measuring apparatus 110, which is an apparatus for realizing the present invention, includes a signal extractor 111, a Wigner distribution calculator 112, an instantaneous spectrum 113, and a peak shape measuring apparatus 1.
14 and the shape calculator 115. The signal extractor 111 receives the received signal trains of the left and right beams and the position of the measurement object designated by the user or the like, and the shape calculator 115 outputs the shape measurement result of the measurement object.

The outline of each device constituting the shape measuring device 110 will be described below.

The signal extractor 111 cuts out a signal sequence of a preset time length, which includes the position of the measured object designated by the user or the like, from the input received signal sequence of the left and right beams, and each Wigner distribution calculator. Output to 112. Here, the signal sequences of the cut out left and right beams are set as SL (t) and SR (t), respectively.

The Wigner distribution calculator 112 calculates the Wigner distribution of SL (t) and SR (t) input from the signal extractor 111. An example of Wigner distribution calculation result
3 shows. The horizontal axis represents time and the vertical axis represents frequency. In the figure, the magnitude of the Wigner distribution spectrum is shown in gray scale, and the spectrum becomes larger as it gets closer to black. The Wigner distribution spectra of the signals SL (t) and SR (t) at time t and frequency f are represented by symbols WL (t, f) and WR.
It is represented by (t, f). The Wigner distribution calculator 112 calculates the calculated Wigner distribution spectra WL (t, f) and WR (t,
f) is output to the instantaneous spectrum calculator 113.

The instantaneous spectrum calculator 113 calculates an instantaneous spectrum from the Wigner distribution spectrum input from the Wigner distribution calculator 112. The instantaneous spectra are Wigner distribution spectra WL (t, f) and WR (t,
This is the same as when the frequency f is fixed to a constant value F in f). Here, the frequency F is set to the transmission frequency, and the frequency F
The instantaneous spectrum of is described as IL (F, t) and IR (F, t).
The instantaneous spectrum calculator 113 calculates the calculated instantaneous spectra IL (F, t) and IR (F, t) from the peak shape measuring device 114.
Output to.

The peak shape measuring device 114 uses the instantaneous spectrum input from the instantaneous spectrum calculator 113 as shown in FIG.
1, the rising positions Tsl, Tsr, and the peak position T
l, Tr and the falling positions Tel, Ter are measured, and the measurement result is output to the shape calculator 115.

The shape measuring instrument 115 is the peak shape measuring instrument 1
The position (x, y) of the measurement object is calculated from the position information of the instantaneous spectrum input from 14 using Equation 3.

In the above description, it is assumed that the hydrophones of the transmitting and receiving device are arranged in the horizontal direction, and the hydrophones are separated from the "left" and "right" beams, but the positional relationship between the two beams is that of the hydrophones. It depends on the placement, eg "up" if the hydrophones are arranged vertically.
Separated from the "lower" beam.

Next, the object measuring device according to the first embodiment of the present invention will be described with reference to the overall configuration diagram shown in FIG.

The object measuring device 130 is composed of a beam forming device 131 and a shape measuring device 110 in addition to the devices constituting the conventional object display device 10 of FIG.
In the object measuring apparatus according to the first embodiment of the present invention, the wave receiving portion of the wave transmitting / receiving apparatus is composed of a hydrophone or a wave receiver linearly arranged in any one direction as shown in FIG. Further, in the device constituting the conventional object display device, the functions of the wave transmission / reception device 132 and the display device 133 are different from the conventional ones. The functions of the wave transmission / reception device 132, the beam forming device 131, and the display device 133 will be described below.

The wave transmitting / receiving device 132 has a function of converting a transmission signal generated by the transmitting device 11 into an ultrasonic wave and transmitting the same, and receiving a reflected wave and converting into an electric signal as in the conventional case. A point different from the conventional one is that the signal is output to the receiving device 13 and the beam forming device 131.

The beam forming device 131 is a wave transmitting / receiving device 13.
A signal input from 2 is subjected to a phasing process to form two acoustic beams. Therefore, the configuration is the same as the wave transmitting / receiving device 1.
It depends on the configuration of 32.

For example, when the transmitting / receiving device 132 is composed of N hydrophones arranged linearly in the horizontal direction, the beam forming device 131 has the structure shown in FIG.
The beam forming device 131 includes a left beam former 141 that forms a left beam and a right beam former 142 that forms a right beam.

The configurations of the left beam former 141 and the right beam former 142 are almost the same as the configuration of the receiving apparatus 13 of FIG. 2, but the number of hydrophone outputs input to each apparatus is different. That is, the number of hydrophone outputs input to the left beam former 141 and the right beam former 142 is
It is half the number input to the receiving device 13. The left beam former 141 and the right beam former 142 radiate a fixed number of beams within a fixed range as shown in FIG. Then, the result is output to the shape measuring device 110.

Here, the receiving device 13 and the beam forming device 1
The difference between the functions of 31 will be described. As described above, the difference between the two is only the number of input hydrophone outputs.
The receiving device 13 forms a beam from N hydrophone outputs, while the beam forming device forms a beam from (N / 2) hydrophone outputs. Therefore, when the receiving device is configured to form a beam from (N / 2) hydrophone outputs and output the beam to the display device via the signal processing device, the receiving device 13 and the beam forming device 131 have the same configuration. In this case, it is not necessary to install the beam forming device, and the result of the receiving device 13 is output to the signal processing device 14 and the shape measuring device 110. When the received signals input to the signal processing device 14 and the shape measuring device 110 are equal in this way, the beam forming device 131 is not installed and the output of the receiving device 13 is output to the signal processing device 14 and the shape measuring device 110. Enter the configuration.

In addition, as shown in FIG.
When the beam forming device 131 includes a wave transmitter and two wave receivers, the beam forming device 131 includes a power amplifier and a digital converter corresponding to the received signals of the two wave receivers as shown in FIG. Is output to the shape measuring device 110.

Next, a shape measuring apparatus according to a second embodiment of the present invention will be described. The configuration is the first of the present invention in FIG.
The configuration is the same as that of the shape measuring apparatus of the above embodiment, but the wave receiving portion of the wave transmitting / receiving apparatus 132 and the configuration of the beam forming apparatus 131 are different. In the shape measuring apparatus according to the second embodiment of the present invention, the wave receiving portion of the wave transmitting / receiving apparatus is configured as a set of hydrophones linearly arranged in a plurality of directions. As an example showing the configuration, consider a case where hydrophones are two-dimensionally arranged as shown in FIG. In this case, it can be considered that N hydrophones are arranged horizontally, vertically, on the right slant and on the left slant.

The hydrophone of the transmitting / receiving device 132 is shown in FIG.
In the case of the above configuration, the beam forming device 131 includes an input signal switching device 181, a first beam forming device 182, and a second beam forming device 183 as shown in FIG.

The input signal switch 181 is used by the wave transmitting / receiving device 13
From the N2 hydrophone outputs input from 2, only the N hydrophone outputs are output to the first beam former 182 and the second beam former 183. The N hydrophone outputs are arranged in four directions, that is, in the horizontal direction, the vertical direction, the rightward oblique upward direction, and the left oblique upward direction, and the inputs are sequentially switched to the other directions. For example, when it is desired to measure the shape in the order of horizontal, vertical, on the right slant, and on the left slant, FIG.
The output of the hydrophone is switched in the order from (d) to (d). Since the horizontal direction is initially horizontal, the horizontal hydrophone output shown in FIG. 21 (a) is input, and the hydrophone output input thereafter is vertical, diagonally right up, and left in FIGS. 21 (b), (c), and (d). Switching to the obliquely upward direction, the (N / 2) hydrophone outputs are output to the first beam former 182 and the second beam former 183.
Output to.

The functions of the first beam former 182 and the second beam former 183 are similar to those of the left beam former 141 and the right beam former 142. Input (N /
2) Form a beam from the outputs of the hydrophones.

The display device 133 has a function of outputting the position of the measuring object designated by the user or the like to the shape measuring device 110 in addition to the conventional function of displaying the video signal input from the signal processing device 14 on the display screen. And a function of displaying the measurement result input from the shape measuring device 110 on the screen. FIG. 22 shows a display example of the measurement result. By enlarging and displaying only the measurement object as shown in the drawing, the user can recognize the position and shape of the measurement object with high accuracy.

As described above, according to the embodiment of the present invention, in the object display device for displaying the positions of the reflected signals from an unspecified number of objects existing within the transmission range, the received signal is subjected to a phasing process, and an acoustic signal is generated. A means for forming a beam, a means for extracting a signal sequence including a reflected signal designated by a user from each formed beam, and a Wigner distribution analysis for the extracted signal sequence to measure an instantaneous spectrum. Means, means for measuring the rising position, maximum position, and falling position of the spectrum from the measured instantaneous spectrum; and means for measuring the position and shape of the object that emits the reflected signal from the temporal position of each measured point. An object display device having a function of causing a user to recognize the position and shape of the object with high accuracy by providing It is.

Further, the object display device of the above-mentioned embodiment is mounted on a ship and radiates a sound wave in the water, processes the reflection signal and displays the result. It is not limited to the configuration. For example, radio waves may be used instead of sound waves, and the present invention can be applied to a configuration in which an object in the atmosphere is displayed.

[0046]

According to the present invention, a received signal is subjected to a phasing process to form an acoustic beam, and a signal train including a reflected signal designated by a user or the like is extracted from each of the formed beams. Means, means for measuring the instantaneous spectrum by performing Wigner distribution analysis on the extracted signal sequence, and means for measuring the rising position, maximum position and falling position of the spectrum from the measured instantaneous spectrum, By having means for measuring the position and shape of an object that emits the reflected signal from the temporal position of each point, it has a function of allowing the user to recognize the position and shape of the object with high accuracy. An object display device is provided.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a conventional object display device.

FIG. 2 is a diagram showing a configuration of a wave receiving portion of a wave transmitting / receiving device 12 and a receiving device 13.

FIG. 3 is a diagram showing a configuration of a phasing processor 24.

FIG. 4 is a diagram showing beam forming in the transmission / reception device 12 and the reception device 13.

FIG. 5 is a diagram showing an example of a display screen.

FIG. 6 is a view showing a shape comparison between an actual object having a high reflectance and a display screen.

FIG. 7 is a diagram showing an arrangement of devices and object measurement.

FIG. 8 is a diagram showing an outline of Tl and Tr measurement using a time waveform.

FIG. 9 is a diagram showing an outline of Tl and Tr measurement using an instantaneous spectrum.

FIG. 10 is a diagram showing a difference in reflection points between a large object and a small object.

FIG. 11 is a diagram showing an outline of a shape measuring method.

FIG. 12 is a diagram showing a configuration of an apparatus for implementing the present invention.

FIG. 13 is an example showing a Wigner distribution calculation result.

FIG. 14 is a diagram showing a configuration of an object display device according to an embodiment of the present invention.

FIG. 15 is a diagram showing an example of the configuration of a beam forming device 131.

FIG. 16 is a diagram showing formation of left and right beams.

FIG. 17 is a wave transmitting / receiving device including one wave transmitter and two wave receivers.

FIG. 18 is a diagram showing an example of the configuration of a beam forming device 131.

FIG. 19 is a wave transmission / reception device including a two-dimensionally arranged hydrophone.

FIG. 20 is a diagram showing another example of the configuration of the beam forming apparatus 131.

FIG. 21 is a diagram showing switching of hydrophone output.

FIG. 22 is a diagram showing a display example of measurement results.

[Explanation of symbols]

12: Wave transmitter / receiver device, 13: Receiver device, 131: Beam forming device 15: Display device, 24: Arrangement treatment device

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Jun Sasaki 216 Totsuka-cho, Totsuka-ku, Yokohama-shi, Kanagawa Hitachi, Ltd. Information & Communication Division (72) Inventor Izumi Taniguchi 216 Totsuka-cho, Totsuka-ku, Yokohama-shi, Kanagawa Hitachi, Ltd. Information & Communication Division (72) Inventor Shoji Fujii 216 Totsuka-cho, Totsuka-ku, Yokohama-shi, Kanagawa Hitachi, Ltd. Information & Communication Division (56) Reference JP-A-8-271612 (JP, A) Special Kaihei 5-180936 (JP, A) JP 9-145834 (JP, A) JP 9-304528 (JP, A) JP 59-27279 (JP, A) JP 61-138188 ( JP, A) JP 61-223575 (JP, A) JP 63-85477 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G01S 15/00-15/96 G01S 13/00-13/95 G01S 7/00-7 / 64

Claims (4)

(57) [Claims] 1. A means for transmitting sound waves or radio waves, such as a sonar, radar, etc., for receiving reflected signals from an unspecified number of objects existing within the transmission range with respect to the transmitted signals, and converting the received signals into video signals. And a means for displaying the converted reception signal on the display screen, and an object measuring device for displaying on the screen the positions of the reflection signals from an unspecified number of objects existing in the transmission range. For any measurement object specified by
As a means for measuring the position and shape of an object with high resolution, if the means for receiving the reflected signal is composed of hydrophones that are linearly arranged in one arbitrary direction, the received signal received by each hydrophone is Phasing process 2
A means for forming an acoustic beam of a book, a means for extracting a signal sequence including a reflected signal designated by a user or the like from each of the formed beams, and a signal sequence by performing Wigner distribution analysis on the extracted signal sequence. Means for calculating the frequency spectrum of, the means for extracting the specific frequency spectrum from the obtained frequency spectrum and measuring the temporal change, and the rising position, the maximum position and the maximum position of the spectrum from the temporal change of the measured specific frequency spectrum. An object measuring apparatus comprising: a means for measuring a falling position; and a means for measuring a position and a shape of a measuring object from a temporal position of each measured point. 2. A means for transmitting sound waves or radio waves, such as a sonar, radar, etc., for receiving reflected signals from an unspecified number of objects existing within the transmission range with respect to the transmitted signals, and converting the received signals into video signals. And a means for displaying the converted reception signal on the display screen, and an object measuring device for displaying on the screen the positions of the reflection signals from an unspecified number of objects existing in the transmission range. For any measurement object specified by
As a means for measuring the position and shape of an object with high resolution, when the means for receiving a reflected signal is configured as a set of hydrophones linearly arranged in a plurality of directions, a hydrophone arranged in any one direction is used. Means for extracting a received signal to be received, means for performing a phasing process on the extracted received signal to form two acoustic beams, and a signal including a reflected signal designated by a user or the like from each formed beam For the means for extracting the sequence and the extracted signal sequence,
A means for calculating the frequency spectrum of the signal sequence by performing Wigner distribution analysis, a means for extracting a specific frequency spectrum from the obtained frequency spectrum and measuring the temporal change, and a time change of the measured specific frequency spectrum. To measure the rising position, maximum position and falling position of the spectrum, to measure the position and shape of the measuring object from the temporal position of each measured point, and to switch the array direction of the hydrophone to be extracted. An object measuring device comprising: means and means for performing the same processing as described above on a received signal after switching. 3. A means for transmitting sound waves or radio waves, such as a sonar or radar, and reception of reflected signals from an unspecified number of objects existing within the transmission range with respect to the transmitted signals by wave receivers located at a plurality of points. Means, a means for converting the signal received at each receiving point into a video signal, and a means for displaying the converted received signal on a display screen, from an unspecified number of objects existing within the transmission range. In the object measurement device that displays the position of the reflected signal, for any measurement object specified by the user,
As a means for measuring the position and shape of an object with high resolution, when the means for receiving the reflected signal is composed of two wave receivers linearly arranged in one arbitrary direction, the received signals received by the two wave receivers Means for extracting a signal sequence including a reflection signal designated by the user from the above, means for calculating the frequency spectrum of the signal sequence by performing Wigner distribution analysis on the extracted signal sequence, and the obtained frequency spectrum Means to extract a specific frequency spectrum from the measured time change, means to measure the rising position, the maximum position and the falling position of the spectrum from the time change of the measured specific frequency spectrum, An object measuring device, comprising: means for measuring the position and shape of a measuring object from a temporal position. 4. A means for transmitting sound waves or radio waves, such as a sonar, radar, etc., and reception of reflected signals from an unspecified number of objects existing within the transmission range with respect to the transmitted signals by receivers located at a plurality of points. Means, a means for converting the signal received at each receiving point into a video signal, and a means for displaying the converted received signal on a display screen, from an unspecified number of objects existing within the transmission range. In the object measurement device that displays the position of the reflected signal, for any measurement object specified by the user,
As a means for measuring the position and shape of an object with high resolution, when the means for receiving a reflected signal is configured as a set of wave receivers linearly arranged in a plurality of directions, an arbitrary 1
Means for extracting a received signal received by the wave receivers arranged in a direction, means for extracting a signal sequence including a reflected signal designated by a user or the like from the extracted received signal, and a Wigner for the extracted signal sequence. A means for calculating the frequency spectrum of the signal sequence by performing a distribution analysis, a means for extracting a specific frequency spectrum from the obtained frequency spectrum and measuring the temporal change, and a time change of the measured specific frequency spectrum. The rising position of the spectrum,
After the switching, a means for measuring the maximum position and the fall position, a means for measuring the position and shape of the measurement object from the temporal position of each measured point, and a means for switching the array direction of the receiver to be extracted, And a means for performing the same processing as described above on the received signal of 1.