JPS6252478A - Acoustic depth sounder - Google Patents

Abstract

PURPOSE:To make it possible to easily and accurately detect the depth of water even if there is disturbance, by taking the correlation between an estimated theoretical receiving wave from and an actually obtained receiving wavelength to detect the difference with an estimated value. CONSTITUTION:A correlation processor 9 receiving an estimated theoretical wave form (standard reflected wave form) signal 18 and a receiving signal 6 outputs the correlation signal 19 showing the correlation of input signals 18, 6. A max. correlation detector 10 outputs a depth-of-water signal 21a showing the depth-of-water value of a vertical component on the basis of the correlation shown by the correlation signal 19 and the delay time at the time of the max. correlation. As mentioned above, because the max. value of correlation may be detected by taking correlation, the depth of water can be easily and accurately detected even if the receiving wave form is distorted because of the presence of a disturbance factor.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to an acoustic sounding instrument, and particularly to an acoustic sounding instrument using an oblique acoustic beam.

(Prior Art) Conventionally, this type of acoustic sounding instrument has mainly adopted a method of measuring the water depth directly below the sounding point using a vertical acoustic beam. In conventional acoustic sounding instruments, due to the characteristics of sound propagation due to perpendicular incidence on the water bottom and reflection, water depth values are determined by time-depth conversion by capturing the rising edge of the received signal waveform reflected from the water bottom. A method was used to obtain

(Problems to be Solved by the Invention) The conventional acoustic sounding device described above uses a vertical acoustic beam, so it can only obtain water depth values directly below, and has the disadvantage of poor sounding efficiency. Therefore, a method of performing simultaneous multi-point sounding using oblique acoustic beams may be considered.

However, when an oblique acoustic beam is used, compared to when a vertical acoustic beam is used, the received waveform has a lower acoustic backscatter intensity on the water bottom surface due to the difference in angle from the vertical direction and the angle of incidence with respect to the water bottom. , the amount of attenuation due to the propagation path difference, the sound irradiation area on the water bottom, and the effects of the sound beam pattern include distortion.

Therefore, if the water depth is measured by capturing the rising b-t from this distorted received waveform, a large error is unavoidable.

(Means for Solving the Problems) Means provided by the present invention to solve the above-mentioned problems is an acoustic sounding instrument having oblique transmitting and receiving oblique acoustic beams that are angled with respect to the vertical. , a standard reflected waveform generator that generates a signal with a standard reflected waveform determined by predicting the reflected waveform on the water bottom due to the acoustic beam pattern, and a correlation between the received signal obtained by electrically converting the received waveform and the standard reflected waveform signal. a maximum correlation detector that detects the maximum correlation value of the output of the cross-correlation processor; and a water depth value calculation output device that converts the time of the maximum correlation value into water depth and outputs the result.

(effect) Next, the present invention will be explained with reference to the drawings.

FIG. 1 provides a detailed explanation of the invention.

Received signal waveform 1 of reflected waves from the water bottom due to oblique acoustic beam
Although the waveform is expanded due to the influence of the water bottom slope, etc., the corresponding water depth value corresponds to the time near the maximum value of the received wave level.

On the other hand, the standard reflection waveform 2 in FIG. 1 is a known waveform that is theoretically determined based on a predicted water depth value.

When we take the cross-correlation in the time domain between the received signal waveform 1 and the standard reflected waveform 2, the cross-correlation curve becomes as shown by code 3, and there is a gap between the maximum correlation point 5 and the maximum value of the standard reflected waveform 2. are different by delay time T.

Therefore, compared to the acoustic propagation time for the predicted water depth value, the propagation time of the actual propagation path differs by the delay time T, and this time difference T is converted into a propagation distance to obtain the corresponding water depth value.

(Embodiment) FIG. 2 is a block diagram showing an embodiment of the present invention. The received signal 6 is input to a cross-correlation processor 9 . The standard reflection waveform generator 8 generates a standard reflection waveform signal 18 representing a received signal waveform that can be theoretically obtained from the predicted water depth value. A cross-correlation processor 9 receiving the standard reflected waveform signal 18 and the received signal 6 outputs a correlation signal 19 representing the cross-correlation of the input signals 18 and 6. The maximum correlation detector 10 determines the delay time T at the time of maximum correlation based on the cross-correlation represented by the correlation signal 19.
A delay time signal 20 representing . The water depth value calculation output device 11 outputs a water depth signal 21a representing the water depth value of the vertical component based on the delay time T represented by the delay time signal 20. In addition, these series of processes are performed using a control signal 22 a * 22 sent from the controller 12 in synchronization with the transmission trigger 7.
It is carried out gradually according to b e 22 c -22d.

(Effects of the Invention) As explained above, the present invention detects the difference between the predicted value and the predicted value by cross-correlating the predicted theoretical received waveform (standard reflected waveform) with the actually obtained received waveform. to obtain the corresponding water depth value.

Therefore, according to the present invention, since the maximum value of the correlation can be detected by taking the cross-correlation, the water depth can be easily and accurately detected even if the number of disturbance elements is 6 and the received waveform is distorted.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the concept of the invention, and FIG. 2 is a block diagram showing an embodiment of the invention. 1... Received signal waveform, 2... Standard reflected waveform, 3...
- Cross-correlation curve % 5... Maximum correlation point, 6... Received signal, 7... Transmission trigger, 8... Standard reflection waveform generator, 9... Cross-correlation processor, 10... Maximum correlation detector, 11...water depth value calculation output device, 12...controller. Agent Patent Attorney Shinsuke Honjo Figure 1 Figure 2

Claims (1)

[Claims] A standard reflection waveform generator that generates a standard reflection waveform signal determined by predicting the reflection waveform of the water bottom due to the pattern of the acoustic beam in an acoustic sounding instrument having oblique transmission and reception oblique acoustic beams forming an angle with respect to the vertical. a cross-correlation processor that correlates the received signal obtained by electrically converting the received waveform with the standard reflected waveform signal; a maximum correlation detector that detects the maximum correlation value of the output of the cross-correlation processor; An acoustic sounding instrument comprising a water depth value calculation output device that converts the time value into water depth and outputs the result.