JP2679192B2 - Undersea terrain display - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seabed terrain display device, and more particularly, to an acoustic wave via a fan-shaped transmission / reception characteristic formed vertically downward from a ship traveling along a predetermined route. TECHNICAL FIELD The present invention relates to a seabed topography display device that transmits and receives fan beams by, continuously obtains simultaneous multipoint topography data on the seabed, and displays the data.

[Conventional technology]

Conventionally, this type of seabed topography display device has adopted a method of forming a plurality of independent acoustic beams in a desired direction of irradiation to irradiate the seabed in a multi-point manner at the same time, and obtaining the seabed topography from the reflected waves.

[Problems to be Solved by the Invention] The above-mentioned conventional seafloor topography display device is a method of forming a plurality of acoustic beams independently of each other by a plurality of sounding instruments capable of performing multi-point sounding at the same time. There is a drawback that the transmitter / receiver is remarkably large in order to improve the measurement efficiency, and the device scale is increased in order to increase the number of sounding points and the mounted platform is also restricted.

An object of the present invention is to eliminate the above-mentioned drawbacks, relieve the constraints of the platform significantly, and provide a seabed terrain display device capable of displaying continuous seabed terrain with a simple structure.

[Means for solving the problem]

The device of the present invention is a seabed topography display device for displaying the topography of the seabed by reflected waves continuously obtained while emitting an acoustic beam from a ship traveling along a predetermined route toward the seabed. Fan beam transmitting and receiving means for acquiring reflected sound from the sea bottom while moving along the route via a fan-shaped transmitted wave and received beam formed below with a predetermined inclination from the vertical direction and A continuous Doppler shift included in a reflected sound obtained from a continuous seabed reflecting surface corresponding to the movement of the fan beam transmitting / receiving means,
A seabed topography that compares the continuous Doppler shift by the fan beam transmitting / receiving means modeled for a flat seabed in advance and displays the seabed topography based on the difference data of the two continuous Doppler shifts corresponding to the seabed topography And a display means.

〔Example〕

Next, the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of one embodiment of the present invention. The embodiment shown in FIG. 1 has a line array structure in which a transmitting and receiving beam is formed by a fan beam having a predetermined divergence angle vertically downward with respect to the traveling direction of a ship, and a transmitting pulse and a reflected sound are transmitted and received. The wave transmitter / receiver 1, a fan beam transmitter / receiver 2 that gives a predetermined fan beam characteristic to the wave transmitter / receiver 1 to transmit / receive a transmission / reception signal in seabed reflection, and a Doppler shift included in the seabed reflected sound acquired by the fan beam transmitter / receiver 2. , The seabed topography display unit 3 that calculates and preliminarily calculates the modeled hypothetical seafloor, obtains the seafloor topography data by obtaining the difference from the Dorla shift, and controls the overall operation control. And part 4.

Next, the operation of the embodiment shown in FIG. 1 will be described. Second
The figure is an illustration of fan beam transmission and reception in the embodiment of FIG.

A fan-shaped fan beam 5 having a predetermined inclination δ from the vertical direction to the traveling direction at a point B ₀ on the route L from a transducer 1 equipped on a ship 11 traveling along the prescribed route L on the sea. To the bottom of the sea, and receive the echo sound of the seabed region 6 at the point A ₀ of the traveling distance D corresponding to the elapsed time between transmission and reception,
Then repeat continuously. For example, the transmitted acoustic signal 7 is reflected at the point P of the seabed area 6 and becomes the reflected signal 8 and is captured at the point A ₀ . In Figure 2, A and B are points A on the sea, respectively.
There are submarine projection points of ₀ and B ₀ .

FIG. 3 is an explanatory diagram of Doppler shift occurrence in the fan beam transmission / reception of FIG.

The reflected signal from the seabed is received by the transmission signal of the vertical acoustic beam due to the transmission / reception directivity of the fan beam pattern orthogonal to the traveling direction of the ship 11, and the reflection by the movement of the ship 11 corresponding to the reflection position of the seabed is received. By detecting the frequency shift of the signal, that is, the Doppler shift, the depth corresponding to the reflection position of the seabed is continuously obtained.

The signal received at the point A ₀ in FIG. 2 corresponds to the reflection point direction of the moving velocity vector 9 of the transducer 1 mounted on the ship 11 with respect to the reflected signal sound velocity vector 10a from the reflection point P in FIG. The Doppler effect is imparted by the reflection point-corresponding velocity vector component 10b to cause a Doppler shift in the reception frequency, and the frequency changes corresponding to the reflection point direction. The frequency shift amount Δf due to the Doppler effect can be determined in advance by the moving speed of the transducer 1 and the direction of the reflection point including depth information if the seabed is uniformly flat.
A Doppler shift that increases as it moves to a reflection point in a direction gradually distant from immediately below is generated.

In this case, the difference between the Doppler shift of the modeled flat seabed determined in advance and the Doppler shift of the received signal actually obtained is caused by the height of the seabed, that is, the seafloor topography. The basic feature of the present invention is to perform the inverse calculation.

FIG. 4 is a characteristic diagram for explaining the method of obtaining the seabed topography from the Doppler shift in the present invention.

FIG. 4 (a) is a modeled Doppler shift characteristic diagram of the flat seabed. As the received wave moves to a reflection point in a direction that gradually moves away from the sea point reflection start point Q immediately below, a frequency shift Δf due to Doppler occurs and the assumed flatness is obtained. The Doppler shift 12 when the seabed is flat due to a large seafloor can be expressed as gradually increasing with a specific function from the seafloor reflection start point Q immediately below.

FIG. 4B is a Doppler shift characteristic diagram based on the actual seabed, and shows the Doppler shift 12 when the seabed is flat, which is shown in FIG. Fig. 4 (b) shows that for a modeled flat seabed exhibiting a Doppler shift of 12 when the seabed is flat, the amount of Doppler shift included in the reflection from the deeper seabed becomes large at the q point as a boundary, and from the shallower seabed. The amount of Doppler shift included in the reflection of is small and exhibits frequency shift characteristics such as deep sea bottom Doppler shift 14 and shallow sea bottom Doppler shift 13, respectively. Of the two frequency shift characteristics shown in FIG. 4 (b), the flat modeling characteristic indicated by the dotted line is previously determined by the moving speed of the transceiver 1 and the reflection point direction, and the reflection point direction includes depth information. Be done.

The depth information of the sea area for which the seabed topography is sought is already known, and ships 11
The speed and fan beam characteristics of are also known. Further, the irradiation field of the seabed that is irradiated by one transmission beam irradiation is also known. Therefore, for example, set the direct point for each of the modeled flat seabeds of various depths as a representative point, and calculate the Doppler shift associated with the platform progress for each of these representative points in advance and store it in the function form for each depth. It is possible to extract the fluctuation amount of the Doppler shift due to the shape of the seabed by preparing this as a Doppler shift by the virtual flat seabed and subtracting this from the actual Doppler shift. The Doppler shift 15 corresponding to the seafloor topography obtained in this way is shown in FIG. 4 (c).

 Returning to FIG. 1, the description of the embodiment will be continued.

The fan beam transmission / reception unit 4 includes a transmitter 21, a transmission power amplifier 22, and a transmission system that forms a transmission fan beam in combination with the transmitter / receiver 1, and a receiver including a receiver 24 and a reception directivity former 25. And a transmission / reception switch 23, and the transmitter 21 is operated by the transmission trigger 201 from the control unit 4, and the transmission electric signal generated by the transmitter 21 is amplified by the transmission power amplifier 22 in accordance with the fan beam characteristic, The transmission / reception switch 23, which is controlled by the transmission / reception switching signal 202 output from the control unit 4, is converted from the wave transmitter / receiver 1 having the line array configuration into a predetermined fan-shaped transmission acoustic beam and transmitted to the water. The reflected wave from the seabed is again received by the transmitter / receiver 1, passed through the transmission / reception switch 23, formed into a predetermined fan-shaped received acoustic beam by the wave reception directivity former 25, and output as a required level signal by the receiver 24. To be done. The receiver 24 receives the reception control signal 203 of the control unit 4.
The receiving operation is performed together with the wave receiving directivity forming device 25 while receiving.

The received signal output from the fan beam transmitting / receiving unit 2 is supplied to the seabed topography display unit 3.

The seafloor topography display unit 3 includes a frequency shift circuit 31 for extracting a Doppler frequency component included in the received signal, a Doppler frequency component for the flat seabed modeled from the Doppler frequency component extracted from the received signal, and a Doppler frequency corresponding to the seabed. Frequency shift subtraction circuit 32 for extracting components, frequency / level conversion circuit 33 for converting Doppler frequency components corresponding to the seabed to a level corresponding to the seafloor topography, direct depth calculation for converting and outputting the level corresponding to the seafloor topography Output circuit 34,
Based on the depth immediately below the previous bathymetric, modeled at approximately the same depth that has been set and stored in advance.Frequency shift amount function generation circuit 35 that outputs the Doppler frequency shift amount of the function representation by the flat seabed, and display 36 Consists of

The frequency shift detection circuit 31 compares the reception signal with the transmission frequency, extracts the Doppler frequency component, and outputs the Doppler shift signal.
It is supplied to the frequency shift subtraction circuit 32 as 311.

The frequency shift amount function generation circuit 35 operates by receiving the trigger signal 302 from the control unit 4, receives the moving speed information 352 of the ship 11, that is, the wave transmitter / receiver 1 from the outside, and the direct depth calculation output circuit 34 described later. Depth signal 341 immediately below from the last transmission
Then, the frequency shift amount of the modeled flat seabed, which is driven by the trigger signal 302 sent from the control unit 4 and corresponds to the depth in the vicinity of the immediately below depth at the time of the previous transmission, is continuous as shown in FIG. 4 (a). Frequency shift function expressed in function quantity 351
Is supplied to the frequency shift subtraction circuit 32.

The frequency shift subtraction circuit 32 subtracts the Doppler frequency by the assumed flat sea surface expressed by the frequency shift function 351 from the input Doppler shift signal 311, and the Doppler frequency corresponding to the seafloor topography reflecting the actual seabed unevenness with respect to the assumed flat sea surface. Is supplied to the frequency / level conversion circuit 33 as the seabed topography corresponding frequency shift signal 321.

The frequency shift signal 321 corresponding to the seafloor topography is converted into a level output corresponding to the seafloor topography by the frequency / level conversion circuit 33 and supplied and displayed on the display 36. This indicator 36
The sweep is activated by the display sweep trigger 301 provided from the control unit 4.

On the other hand, the frequency / level conversion circuit 33 corresponding to the seabed topography
The output of is supplied to the direct depth calculation output circuit 34, and the direct depth signal 341 is obtained and output to the frequency shift amount function generation circuit 35 to generate the frequency shift function in the case where the seabed at the next bathymetry is flat. It is a depth parameter.

Note that the depth immediately below is given as an initial depth value 301 from the outside only during the first sounding.

In this way, the seabed topography is displayed continuously without using many sounding instruments based on the fan-beam transmission / reception and the seabed topography information obtained through the Doppler frequency difference of the assumed flat seabed where the actual Doppler frequency and depth are almost the same. be able to.

〔The invention's effect〕

INDUSTRIAL APPLICABILITY As described above, according to the present invention, the frequency shift amount of the Doppler shift of the acoustic signal due to the movement of the fan beam transmitter / receiver is continuously measured as a frequency shift amount corresponding to the seabed topography, and bathymetry is performed. Since it can be displayed as, and the number of acoustic beam forming can be implemented only by the circuit, it can be significantly downsized as compared with the conventional seabed terrain display device of this type, and the condition for the platform can be significantly eased. There is.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention, FIG. 2 is an explanatory view of fan beam transmission / reception of the embodiment of FIG. 1,
FIG. 3 is an explanatory diagram of Doppler shift occurrence in fan beam transmission / reception in FIG. 2, FIG. 4 (a) is a modeled Doppler shift characteristic diagram by a flat seabed, and FIG. 4 (b) is an example of an actual Doppler shift by the seabed. The Doppler shift characteristic diagram shown in FIG. 4 (c) is a Doppler shift characteristic diagram corresponding to the actual seabed topography based on the Doppler shift difference in FIGS. 4 (a) and 4 (b). 1 ... Transceiver, 2 ... Fan beam transceiver, 3 ...
Submarine topography display unit, 4 …… Control unit, fan beam, 6 ……
Seabed area, 7 ... Acoustic signal, 8 ... Reflection signal, 9 ... Transceiver moving velocity vector, 10a ... Reflection signal sound velocity vector, 10b ... Reflection point corresponding velocity vector, 11 ... Ship, 12 ...
… Doppler shift when the sea floor is flat, 13 …… Shallow sea bottom Doppler shift, 14 …… Deep sea bottom Doppler shift, 15 …… Doppler shift corresponding to seabed topography, 21 …… Transmitter, 22 …… Transmit power amplifier, 23
...... Transmission / reception switch, 24 …… Receiver, 25 …… Reception directivity shaper, 31 …… Frequency shift detection circuit, 32 …… Frequency shift subtraction circuit, 33 …… Frequency / level converter, 34 …… Direct depth calculation circuit, 35 ... Frequency shift amount function generation circuit, 36 ...
…display.

Claims (1)

(57) [Claims] 1. A submarine topography display device for displaying the topography of a seabed by reflected waves continuously obtained while emitting an acoustic beam from a ship traveling along a predetermined route to the bottom of the sea. Fan beam transmitting and receiving means for acquiring reflected sound from the sea bottom while moving along the route via a fan-shaped transmitting and receiving beam formed below by imparting a predetermined inclination from the perpendicular direction and a vertical direction, A continuous Doppler shift included in reflected sound obtained from a continuous seabed reflection surface corresponding to the movement of the fan beam transmitting / receiving unit, and a continuous Doppler shift by the fan beam transmitting / receiving unit modeled in advance for a flat seabed; And a seabed topography display means for displaying the seabed topography based on the difference data of the two continuous Doppler shifts corresponding to the seabed topography. Bathymetry display apparatus characterized in that it comprises a.