JPH02298884A - Aperture synthesizing side scanning sonar - Google Patents

Abstract

PURPOSE:To prevent missed search by compensating the phases of respective receiving signals so that the center of phase synthesis comes to a missing search part and subsequently performing the phase synthesis of the respective receiving signals. CONSTITUTION:When an inputted control signal shows 'phase non- compensation', a phase compensating circuit 7 outputs the output of the corresponding memory circuit 6 to a phase synthesizing circuit 8 as it is but, when the control signal shows 'phase compensation', said circuit 7 performs the predetermined phase compensation with respect to the output of the corresponding memory circuit 6 to output the output of the memory circuit 6 to the phase synthesizing circuit 8. As a result, when missed search is generated, the center of the beam formed by the phase synthesis due to the phase synthesizing circuit 8 is present at the missed search part and azimuth resolving power is formed into DELTAy at a target distance (r). By this method, a desired image free from missed search is displayed on a display device 9.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an aperture synthesis side scan sonar for the purpose of obtaining an outline of the topography of the seafloor using aperture synthesis technology.

(Prior Art) An aperture synthetic side scan sonar is installed on a towing body suspended from an exploration vessel close to the seabed, in the direction of travel of the towed body, that is,
A transducer is installed so that the diagonally downward direction in a plane perpendicular to the direction of travel of the exploration vessel is the direction of transmission and reception, and while the towed body is moving, transmission and reception are repeated, and the waves return from a reflecting body such as the seabed. For example, as shown in Fig. 3, the echo signals are stored together with their phases, and the distance 'p is calculated using the N-th transmission/reception point as the center and the N-time reception signals before and after the N-th transmission/reception point as the target.
By performing phase synthesis corresponding to 1r, a high-resolution seabed uneven surface is obtained. Here, the distance r
The azimuth resolution Δy is given by the length of the transducer 31 being d,
If the wavelength of the acoustic signal used is λ, then Δy=06"'?"'2ma+go −=−−11−−=
It is given by (1).

(Problems to be Solved by the Invention) However, in the above-described conventional aperture synthetic side scan sonar, there is a problem in that when the moving speed of the exploration vessel is high, omissions occur in exploration.

For example, if the exploration range R is about 750 m, the speed of sound underwater is about 1500 m (7 seconds), so the transmission/reception repetition period is 1 second. On the other hand, target distance r=50
0 m, transducer length d = 1 m, wavelength λ - 0.05 m
(equivalent to 30 KHz in underwater sound waves), composite number n = 2
If N+1=21, Δ,y=0.7m.

Then, the moving speed of the exploration ship is set to 5 t (匈2.5 m
/S), when performing aperture synthesis for each transmission and reception,
While traveling 2.5 m, a search width with azimuth resolution of 0.7 m will be obtained at a distance of 500 m, and the remaining 1.8 m will be missed.

That is, conventionally, in order to prevent exploration failures, the moving speed of the exploration vessel must be slowed down, and improvements are desired.

The present invention has been made in view of such problems, and an object thereof is to provide an aperture synthetic side scan sonar that can prevent detection failures even when a research vessel moves at high speed.

(Means for Solving the Problems) In order to achieve the above object, the aperture synthesis side scan sonar of the present invention has the following configuration.

That is, in the aperture synthetic side scan sonar of the present invention, the aperture synthetic side scan sonar: Sends an acoustic signal diagonally downward in a plane perpendicular to the direction of movement underwater, and receives echo signals from a reflector such as the seabed surface. a moving distance measuring circuit that measures the moving distance until the moving distance is reached; a phase setting circuit that sets the phase compensation amount of each received signal so that the phase synthesis center is located at the portion without exploration based on the measured moving distance; a plurality of phase compensation circuits that perform phase compensation for each corresponding received signal based on the amount of phase compensation obtained; and the outputs of the plurality of phase compensation circuits are phase-combined. .

(Function) Next, the function of the aperture synthetic side scan sonar of the present invention configured as described above will be explained.

After compensating the phase of each received signal so that the center of phase combination is located at the missing part of the survey based on the amount of movement of the exploration vessel between each transmission and reception, the received signals are phase-combined. At this time, if the width of the exploration hole is wide, multiple beams are formed.

As a result, it is possible to provide an aperture synthetic side scan sonar that does not miss any detection even when the exploration vessel moves at high speed.

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

FIG. 1 shows an aperture synthetic side scan sonar according to an embodiment of the present invention. As shown in FIG. A plurality of phase compensation circuits 7 are provided between the circuit 6 and a phase synthesis circuit 8 for phase-synthesizing these outputs, corresponding to each memory circuit 6.

In FIG. 1, a pulse signal generated by a transmitter 1 passes through a transmitter/receiver switch 2 and is applied to a transducer 3, and an acoustic signal based on this is radiated diagonally downward into the water. The echo signal from the ocean floor is converted into an electrical signal by a transducer 3, passes through a transceiver switch 2 and a receiver 4, is converted into a digital value by an A/D converter 5, and is then stored in a memory circuit 6.

The above transmission and reception is repeated as the exploration vessel (that is, the platform) moves. For example, if there are 2N+1 memory circuits 6, 2N+1 received signals are stored in the corresponding memory circuits 6 one after another.

On the other hand, the movement distance measuring circuit 11 receives input from outside the country from speed information 12 of a platform (not shown), measures the movement distance between each transmission and reception based on this speed information 12, and outputs it to the phase setting circuit 10. In circuit 10,
It is determined from the input measurement value whether or not a detection gap will occur, and if the platform is moving quickly and the interval between the transmission and reception of the transducer 3 is too large and a detection gap will occur, a check is made as shown in FIG. 2, for example. Calculate and set an appropriate phase correction station for each received signal from the 1st to the 2N+1st time so that the phase synthesis center line A is located at the missing part of the search, as shown in FIG.
It is outputted to each phase compensation circuit 7 as a control signal.

When the input control signal indicates "no phase compensation", the phase compensation circuit 7 outputs the output (received signal) of the corresponding storage circuit 6 as it is to the phase synthesis circuit 8; '', after performing a predetermined phase compensation on the output (received signal) of the corresponding memory circuit 6,
Output to phase composite diagram f\18.

As a result, when a search gap occurs, the beam formed by phase synthesis in the phase synthesis circuit 8 has its center at the search gap, and the azimuth resolution is Δ at the target distance r.
It will be formed so that it becomes y.

In this way, the desired screen is displayed on the display 9 without any omissions in the search.

As is clear from the above description, when the width of the search gap is wide, it is sufficient to set a plurality of phase synthesis center lines and phase compensation amounts corresponding to each in the phase setting circuit 10.

(Effects of the Invention) As explained above, according to the aperture synthesis side-scan sonar of the present invention, based on the amount of movement of the exploration vessel between each transmission and reception, each phase After compensating the phase of each received signal, each received signal is phase-synthesized, which has the effect of providing an aperture-synthesizing side-scan sonar that does not cause search omissions.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the configuration of an aperture synthesis side scan sonar according to an embodiment of the present invention, FIG. 2 is an explanatory diagram of the phase synthesis method of the present invention, and FIG. 3 is an explanatory diagram of a conventional phase synthesis method. . 1...Transmitter, 2...Transmission/reception switch,
3.31... Transmitter/receiver, 4... Receiver, 5... A/D converter, 6... Memory circuit, 7... ...Phase compensation circuit, 8...
...Phase synthesis circuit, 9...Display device, 10.
...Phase setting circuit, 11...Moving distance measuring circuit, 12...Speed information. Agent Patent attorney Yoshi Hachiman Hiroshi Hiroshi real name Hu 0 Vaginal handling Spring Happo person's beard and throat ticket 2 Figure d-11 Sending and receiving j Skin 10 Lk, To-eye spy distance wing, 8/Yama 8
Isuke'4 ability bracken rice/) & Solu Kaio Hiroga mine cutting map

Claims (1)

[Claims] In an aperture synthetic side-scan sonar: A travel distance measuring circuit that transmits an acoustic signal diagonally downward in a plane orthogonal to the direction of movement underwater and measures the travel distance until it receives a reverberant signal from a reflector such as the ocean floor. and; a phase setting circuit that sets the phase compensation amount of each received signal so that the phase synthesis center is located at the search missing portion based on the measured moving distance; and for each of the corresponding received signals based on the set phase compensation amount. An aperture synthesis side scan sonar comprising: a plurality of phase compensation circuits that perform phase compensation; and outputs of the plurality of phase compensation circuits are phase-synthesized.