JPS6327785A - Apparatus for displaying topography of sea bottom - Google Patents

Abstract

PURPOSE:To accurately measure the distance up to the sea bottom, by a method wherein a sonic wave is emitted to output a standard reflected wave corresponding to the estimated depth of water down to the sea bottom and the actual depth of water is operationally processed on the max. correlation between the standard reflected wave and receiving output. CONSTITUTION:The receiving signal 22 of a receiving circuit 12 is sent to a mutual correlation processing circuit 14 and the output signal 23a of a standard reflected wave form generating circuit 13 is compared with the receiving signal 22 to perform correlation processing. The standard reflected wave form generating circuit 13 generates a standard reflected wave becoming a standard on the basis of the output 23b of a depth-of-water value operation output circuit 16. A max. correlation detection circuit 15 detects the max. correlation between the receiving signal 22 and the output signal 23a on the basis of the output of the mutual correlation processing circuit 14 and detects the time difference of both signals based on the max. correlation. The depth-of-water value operation output circuit 16 converts the time difference to a distance corresponding to the output of the max. correlation detection circuit 15 to operate the depth-of- water value down to the sea bottom.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention is based on the acoustic sounding instrument KI! AL, Patent This invention relates to a submarine topography display device that uses multiple acoustic beams to simultaneously measure and search not only the seabed immediately below a ship but also the vicinity directly below it using an oblique beam to display the topography of the seafloor.

(Prior Art) Conventionally, this type of submarine topography display device is equipped with a line array transducer that forms a cross-fan beam with wide directivity in the vertical plane, and can simultaneously measure depth at multiple points using multiple acoustic beams. It has become common practice to carry out measurements and display a contour map corresponding to the sounding values on a display.

In particular, the sounding value can be determined by temporally selecting the reflected signal near the seabed point corresponding to the received signal of the beam, and determining its rise by setting a certain threshold, that is, the signal level of the reflected signal. The sounding value was calculated by converting the time required until the time when the depth exceeded the threshold value into distance.

(Problems to be Solved by the Invention) In the conventional method of obtaining sounding values described above, the received waveform when measuring with an oblique acoustic beam is based on the difference between the angle of the acoustic beam from the vertical direction and the angle of incidence on the seabed. The acoustic backscattering intensity of the seabed surface due to the noise, the amount of attenuation due to the propagation path difference, the acoustic irradiation area on the seabed, and the acoustic beam pattern include distortion. Measuring water depth by looking at the top has the disadvantage that large errors are unavoidable.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a submarine topography display device that accurately measures the distance to the seabed and displays the topography of the seafloor. Means for Solving the above-mentioned problems and achieving the above object, the present invention provides a submarine topography display device in which a receiving device receives reflected waves of sound waves emitted from a transmitting device on the seabed, etc. A submarine topography display device that displays the topography of the seabed on a display based on the received output of the device, and a standard reflected wave generation circuit that outputs a standard reflected waveform according to a predicted water depth to the seabed from which the sound wave was emitted; The present invention is characterized in that it includes arithmetic processing means for processing the actual water depth based on the maximum correlation between the standard reflected wave and the received output.

(Example) Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention. 1
8 is a controller, and a transmission trigger 19a from the controller 18
The transmitter circuit 6 is activated, and the transmitter electrical signal generated by the transmitter circuit 6 is phased by the transmitter directivity forming circuit 7 in the desired sounding direction, amplified by the transmitter power amplifier circuit 8, and then transmitted to the line array. The electrical signal is converted into an acoustic signal by the transducer 9, and the converted acoustic signal is transmitted to the sea. The desired reflected acoustic signal from the seabed is received by the line array receiver 10, the received acoustic signal is converted into an electrical signal 21, and the receiving directivity forming circuit 11 phase-phases it in the sounding direction. It is received by the receiving circuit 12. Receiving circuit 1
The second received signal 22 is sent to the cross-correlation processing circuit 14. This cross-correlation processing circuit 14 operates in response to a control signal 19i from the controller 18, and performs correlation processing by comparing the output signal 23a of the standard reflected waveform generation circuit 13 and the received signal 22. This standard reflected waveform generation circuit 13 generates a standard reflected wave as a reference based on the output 23b of the water depth value calculation output circuit 16, which will be explained later. 15 is a cross-correlation processing circuit 14
Detect the maximum correlation between the received signal 22 and the output signal 23a based on the output of , and calculate the time difference between the two signals based on the maximum correlation,
That is, it is a maximum correlation detection circuit that detects the amount of delay. 16 is a water depth value calculation output circuit υ, and a control signal 19 of the controller 18
f, and according to the output of the maximum correlation detection circuit 15, that is, the time difference between the received signal 22 and the output signal 23a, the time difference is converted into a distance and the water depth value to the seabed is calculated.

17 is a display device, and the signal 2 of the water depth value calculation output circuit 16
Displays the topography of the ocean floor based on 0. 19b, 19c,
19d.

19e is a control signal for synchronizing each circuit section.

FIG. 2 is a signal waveform diagram in the signal processing circuit 40.

The water depth calculation process will be explained with reference to FIG. The received signal waveform 1 of the wave reflected from the seabed by the oblique acoustic beam is an elongated waveform due to the influence of seafloor tilting, etc., but the corresponding water depth value corresponds to the time near the maximum value of the received wave level. ing.

On the other hand, the standard reflection waveform 2 is a known theoretical waveform based on a water depth value predicted in advance from the previous sounding 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 is as shown by code 3, and there is a curve between the maximum correlation point 5 and the maximum value of the standard reflected waveform 2. produces a difference 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.

(Effects of the Invention) As explained above, the present invention calculates the difference between the expected standard received signal and the actual received signal by calculating the cross-correlation between the expected standard received signal and the actual received signal, thereby making it possible to determine the true sounding value. , it is effective in reducing sounding errors even for received signals with unclear peaks, which is a characteristic of oblique acoustic beams7.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a signal waveform diagram of the main part of FIG. 1. 1... Received signal waveform, 2... Standard reflected waveform, 3...
- Cross-correlation curve, 5... Maximum correlation point, 6... Transmission circuit, 7... Transmission directivity forming circuit, 8... Transmission power amplification circuit, 9... Line array transmitter, 10 ... Line array receiver, 11 ... Reception directivity forming circuit, 12
...Reception circuit, 13...Standard reflected waveform generation circuit, 1
4... Cross correlation processing circuit, 15... Maximum correlation detection circuit, 16... Water depth value calculation output circuit, 17... Display, 18... Controller, 19a to 19i... Control signal ,
20...Water depth value output, 21...Unphased input signal, 2
2... Received signal, 23a... Standard reflected waveform output, 2
3b...Initial value or last sounding value. Agent: Patent attorney Shinsuke Honjo? Figure 2

Claims (1)

[Scope of Claims] A seafloor topography display device that receives reflected waves of sound waves emitted from a transmitter and reflected from the seabed, etc. by a receiver, and displays the topography of the seafloor on a display based on the received output of the receiver, Based on a standard reflected wave generation circuit that outputs a standard reflected wave according to the predicted water depth to the seabed from which the sound wave was emitted, and the maximum correlation between the standard reflected wave of the standard reflected wave generation circuit and the received output of the receiving device. What is claimed is: 1. A submarine topography display device comprising: arithmetic processing means for calculating actual water depth.