JPS63177088A - Sonar apparatus - Google Patents

Abstract

PURPOSE:To protect a transmitter from cavitation by a method wherein the accelera tion of the vertical motion of a dome element is determined from the variation rate of a pitching angle of a ship and transmission is prohibited or delayed when the acceler ation exceeds a direction and a value which are predetermined. CONSTITUTION:A motion sensor 1 installed in a hull detects a pitching angle and transmits it to a pitching acceleration detecting circuit 2. The circuit 2 determines an acceleration to the vertical motion of a dome element from a distance between the center of the motion of the ship and a transmitter 7 on the basis of the variation rate of the pitching angle and transmits same to a pitching phase detecting circuit 3. The circuit 3 generates a transmission prohibition pulse when the acceleration exceeds a direction and a value which are predetermined, and transmits same to a transmission trigger signal generating circuit 5. Meanwhile, sweep control circuit 4 controls a sweep period wherein reception is conducted corresponding to a signal search distance set by a sonar, and subsequent transmission. The circuit 5 compares a sweep end pulse outputted from the circuit 4 with the transmission prohibition pulse transmitted from the circuit 3, and transmits a transmission start pulse only when the result of comparison exceeds a prescribed value. By this method, the damage of the transmitter 7 due to cavitation can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a sonar device that is installed on a ship and uses sound waves to detect underwater objects and display images on a CRT screen or the like.

[Conventional technology]

Typically, the transmitter, which is an electroacoustic transducer of a sonar device installed on a ship, is housed in a dome at the bottom of the bow. The inside of the dome is filled with water and hydrostatic pressure is applied to suppress cavitation on the transmitter surface. However, when the bow of the ship moves up and down due to ship motion, especially pitching, the dynamic pressure generated by the acceleration is added to the hydrostatic pressure, and the water pressure inside the dome increases or decreases compared to the state without motion. do.

[Problem that the invention seeks to solve]

Conventionally, sonar devices repeatedly transmit data at fixed intervals, independent of the ship's motion. Therefore, when the bow moves downward due to pitching and upward acceleration is applied to the water inside the dome, negative dynamic pressure is generated and the water pressure inside the dome is lower than when there is no movement. If transmitted at this time, there is a risk of cavitation occurring. When cavitation occurs, there is a danger that the vibrator, which has a light water load on the transmitter, will overvibrate and be destroyed.

[Means for solving problems]

The present invention detects the pitching angle of a ship and changes its rate of change (
By calculating the vertical acceleration of the dome from the angular acceleration) and prohibiting transmission when it exceeds a predetermined direction and value, and delaying the transmission until the prohibited state is lifted, cavitation due to a drop in water pressure inside the dome can be prevented. The purpose of the present invention is to provide a transmission controller that prevents the occurrence of this phenomenon and prevents damage to the transmitter.

In other words, there is a circuit that detects the pitching angle of the ship, a circuit that calculates the acceleration inside the dome from changes in the pitching angle, and when the acceleration is less than a predetermined value, transmission is prohibited and the prohibited state is canceled. The transmitter is equipped with a circuit that delays the timing of transmission until the dome reaches a certain level, and transmits only when the water pressure inside the dome is above a certain value, thereby preventing damage to the transmitter due to cavitation.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows the blocks of the present invention, and FIG. 2 is a diagram explaining the operation of each part. In FIG. 1, a motion sensor 1 installed on the hull detects the motion of the boat, that is, the pitching angle and rolling angle, and sends a pitching angle signal to a pitching acceleration detection circuit 2. The pitching acceleration detection circuit 2 determines the acceleration with respect to the vertical movement of the dome portion from the rate of change (angular acceleration) of the pitching angle and the distance from the center of vibration of the ship to the transmitter 7, and sends it to the acceleration phase detection circuit 3. When the acceleration exceeds a predetermined direction and value, the acceleration phase detection circuit 3 generates a transmission prohibition pulse and sends it to the transmission trigger signal generation circuit 5. On the other hand, the sweep control circuit 4 controls the reception sweep period and subsequent transmission in accordance with the determined detection distance of the sonar.
When the ship's motion is small, it operates by alternating transmission and reception at regular intervals. The transmission trigger signal generation circuit 5 is
The sweep end pulse output from the sweep control circuit 4 is compared with the transmission prohibition pulse sent from the pitching phase circuit 4, and if they match, a transmission start pulse is generated after the transmission prohibition pulse ends and the transmitter 6 is activated. The wave transmitter 7 sends out sound waves.

In Fig. 2, (a) shows the pitching angle signal output from the vibration sensor, and (b) shows the pitching angle signal outputted from the vibration sensor.
The angular acceleration signal obtained by step differentiation and the ship's pi.

It shows an acceleration signal for the vertical movement of the dome section, which is determined by the distance from the chiming center position to the dome section. (C
) is a transmission inhibit pulse that prevents transmission when the acceleration signal is below a certain value (dashed line in (b) in the figure), that is, when the acceleration exceeds a certain value in a specified direction, and (d) is a sweep control pulse. The sweep end pulse generated by the circuit is shown in (e). If the sweep end pulse matches the transmission prohibition pulse, the transmission prohibition pulse ends. After 7, and if they do not match, the sweep ends. The transmission start pulse t-1(f), which is controlled to occur after the end of the pulse, indicates a transmission signal transmitted in accordance with the transmission start pulse.

Above we have described the method of detecting the pitching angle with a vibration sensor, determining the pitching angular acceleration of the dome section, and further determining the acceleration of the vertical motion of the dome section to control transmission.In the dome section, an acceleration sensor for vertical motion is installed. However, it is clear that a similar effect can be obtained by a method in which transmission is controlled by directly detecting acceleration.

〔Effect of the invention〕

As described above, the present invention detects the acceleration of the vertical movement of the dome, and when the downward acceleration exceeds a predetermined value, the transmission timing is delayed until the condition is recovered. This has the advantage that the wave device can be protected from damage due to cavitation.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of the present invention, and FIG. 2 is a diagram showing the operation of each part of the present invention. DESCRIPTION OF SYMBOLS 1... Shake sensor, 2... Pitching acceleration detection sensor, 3... Pitching phase detection circuit, 4... Sweep control circuit, 5...・・Transmission trigger control circuit, 6th agent Patent attorney Hara Uchi
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Claims (1)

[Claims] In a sonar device that emits sound waves underwater and measures the direction and distance of a target from the echoes, there is a means for detecting vertical acceleration of a sonar dome caused by the motion of a ship, and a direction in which the acceleration is determined in advance. What is claimed is: 1. A sonar device comprising means for prohibiting transmission and delaying transmission when the value exceeds , and allowing transmission only within a predetermined range of vertical acceleration of the transmitter.