JPH0197887A - Image display device in scanning sonar - Google Patents

Abstract

PURPOSE:To implement three-dimensional grasp of the distribution of a school of fish readily, by switching images at a specified time interval, and displaying the image of the school of fish as if moving images are observed. CONSTITUTION:Every time the elevation angle of the ultrasonic wave beam is changed with an elevation angle control circuit 8, an image memory selecting means 16 sequentially selects an image memory 12i, into which an image data are to be stored, out of a plurality of image memories 12a-12n in synchronization with the change in elevation angle. Thus the image data, which have been obtained every time the elevation angle has been changed, are individually stored in each memory 12i. Meanwhile, the image data corresponding to the elevation angles, which are read out of the memories 12 in parallel, are sequentially selected and outputted at a specified period not in synchronization with the writing/reading operations of the memories 12 with a data output selecting circuit 22. As a result, the images of the school of fish are sequentially switched and displayed at a constant interval with the change of the elevation angle as if moving images are observed.

Description

Detailed Description of the Invention <Industrial Application Field> The present invention relates to an image display device for a scanning sonar, and in particular, by displaying images obtained by sequentially changing the elevation angle in a time-sharing manner, underwater depth can be determined. The present invention relates to an image display device that allows the directional distribution of fish schools to be grasped.

<Conventional technology> Normally, schools of fish are often distributed over a certain depth, so when searching for schools of fish using a scanning sonar, the angle of depression and elevation is changed over time, as shown in Figure 3. The ultrasonic beam is transmitted while changing the angle by a constant angle θ. Then, the received signal obtained by receiving the reflected waves from the school of fish under a certain elevation angle is temporarily stored in the image memory as image data, and then the image data is read out from the image memory in synchronization with TV scanning. It outputs to a tCRT monitor and displays images of schools of fish.

<Problems to be Solved by the Invention> As described above, in conventional image display devices, image data obtained based on transmission and reception of ultrasonic beams is output directly to a CRT monitor via a single image memory. Therefore, when the angle of elevation changes, the image of the school of fish changes accordingly.

Therefore, when a school of fish is located close to the scanning sonar, the transmission and reception period of the ultrasonic beam is short, so the angle of elevation can be changed rapidly, and the image of the school of fish changes accordingly. It is relatively easy to understand the fish school distribution because the period is shorter, but if the fish school is located far away, the transmission and reception period of the ultrasonic beam becomes longer, so the elevation angle changes slowly accordingly. As a result, the frequency at which images of schools of fish change becomes longer.
For example, it will switch at intervals of 10 to 15 seconds. As described above, when the cycle of video switching becomes longer, the relationship between the displayed images before and after switching becomes unclear, making it difficult to understand the fish school distribution three-dimensionally.

The present invention has been made in view of the above circumstances, and allows images of schools of fish to be switched and displayed at regular time intervals, like watching a video, so that the images are not affected by the length of the transmission and reception period of the ultrasonic beam. The purpose is to make it easy to understand the distribution of fish schools in three dimensions without having to worry about the situation.

<Means for Solving the Problems> In order to achieve the above object, the present invention adopts the following configuration.

That is, the image display device of the present invention includes a plurality of image memories that store received signals of ultrasonic beams obtained by the transducer as image data, and the plurality of image memories are stored in synchronization with switching of the elevation angle by the elevation angle control circuit. An image memory selection means for sequentially selecting an image memory into which image data should be written from among the image memories, and an image memory writing/reading operation for each image data according to an elevation angle read out from each image memory in parallel. It is configured to include a data output selection circuit that sequentially selects and outputs data asynchronously at a constant cycle.

<Operation> Every time the elevation angle of the ultrasonic beam is changed by the elevation angle control circuit, the image memory selection means sequentially selects an image memory into which image data is to be written from among the plurality of image memories in synchronization with the change in the elevation angle. select.

As a result, image data obtained each time the elevation angle is changed is individually stored in each image memory.

On the other hand, each image data corresponding to the elevation angle read out in parallel from each image memory is sequentially selected and outputted at a constant cycle by a data output selection circuit asynchronously with the write/read operations of the image memory.

As a result, the images of the school of fish are displayed in sequence at regular intervals as the angle of elevation changes, just like watching a video. Therefore, the distribution of fish schools at each depth can be grasped three-dimensionally.

<Embodiment> FIG. 1 is a block diagram including an image display device of a scanning sonar. In the same figure, reference numeral 1 denotes a transducer, which includes a transducer 2 that transmits and receives an ultrasound beam, a transmitter 4 that outputs an excitation pulse of the transducer 2, and a transmitter 4 that outputs a received signal of the ultrasound beam obtained by the transducer 2. It is composed of a receiving section 6 that performs amplification and detection. Further, 8 is an elevation angle control circuit that sequentially changes the elevation angle of the ultrasonic beam outputted from the transducer 2 of the transducer l over time. 10 is an A/D converter that digitizes the received signal from the receiving section 6. 12a to 12n are a plurality of image memories that store A/D-converted received signals of ultrasound beams as image data.

14 is a write permission signal generation circuit that generates a write permission signal in response to a transmission trigger pulse outputted from the elevation angle control circuit 8 every time the elevation angle is changed; A transmission trigger pulse is input, and a plurality of image memories 12a to 12n are synchronized with the input.
The image memory selection means sequentially selects an image memory into which image data should be written from among the image memories, and is composed of, for example, a ring counter. The write permission signal output from the write permission signal generation circuit 14 is applied to the read/write mode setting terminals R/W of the image memories 12a to 12n via the image memory selection means 16 and the OR gates 17a to 17n.

18 is a write address generation circuit that generates a write address for image data for each of the image memories 12a to 12n;
, θ) are orthogonal coordinates (X
, Y). Further, 20 is a read address generation circuit that generates a read address for image data for each image memory 12a=12n.

22 is an image memory 12a that stores each image data corresponding to the elevation angle read out in parallel from each of the image memories 12a to 12n.
-12n is a data output selection circuit that sequentially selects and outputs data at a constant cycle asynchronously with the write/read operation; 24 is a display unit that displays an image of the fish school distribution based on the image data selected by the data output selection circuit 22; .

Next, the operation of the above configuration will be explained.

To understand the distribution of fish schools, the angle of elevation must be set at a constant angle θ over time.
Since it is necessary to transmit and receive the ultrasound beam while changing the ultrasound beam, the elevation angle control circuit 8 switches the elevation angle θ to the transducer 1 at a predetermined period that takes into account the transmission and reception period of the ultrasound beam. A transmission trigger pulse for generating an ultrasonic beam is output. This transmission trigger pulse is
The signal is applied to the transmitting section 4, the receiving section 6, the write permission signal generating circuit 14, and the image memory selecting means 16, respectively.

The transmitter 4 transmits the vibrator 2 in response to this vibration trigger pulse.
An excitation pulse is output to the transducer 2, and an ultrasonic beam is transmitted from the transducer 2. The echoes of the ultrasonic beam reflected by the school of fish are
The wave is received again by the transducer 2, and the received signal from the transducer 2 is amplified and detected by the receiver 6, then digitized by the A/D converter IO, and the data is stored as image data in each of the image memories 12a to 12a. 12n in common.

The write permission signal generation circuit 14 writes data in a predetermined period from input of a transmission trigger pulse to input of the next transmission trigger pulse based on the transmission trigger pulse and the horizontal/vertical synchronization signal of the TV. Outputs write permission signal. That is, writing/reading image data to/from the image memories 12a=12n is much faster in the latter than in the former, so in this example, image data is written by cycle stealing during the data read period from each image memory 12a-12n. Write. Therefore, write permission signal generation circuit 1
4 outputs a high-level write permission signal during the blanking period of the horizontal/vertical synchronization signal. This write permission signal is transmitted to the write address generation circuit 18 and the image memory selection means! 6 is given. Write address generation circuit 18 generates a write address in response to the write enable signal. On the other hand, the image memory selection means 16 selects its signal output terminal 1 every time a vibration transmission trigger pulse is input.
6a to 16n are sequentially switched. Therefore, each time a transmission trigger pulse is output, one image memory is selected, and image data is written into the selected image memory only for a period during which a write permission signal is given. As a result, image data obtained each time the elevation angle is changed is individually stored in each of the image memories 12a to 12n. For example, suppose that the image memory is for 7 screens, and the central elevation angle is 30°, and the elevation angle is changed by 2° within a range of ±6° (i.e., from 24° to 34°). , when image data obtained at an elevation angle of 30° is stored in the fourth image memory, the next fifth image memory has an elevation angle of 32°, the sixth has an elevation angle of 34°, and the seventh has an elevation angle of 36°. The image memory is sequentially selected each time the elevation angle changes, such as 24° for the first, 26° for the second, 28° for the third, 30' for the fourth, and so on. Image data is stored.

Next, the image data stored separately in each of the image memories 12a to 12n according to the elevation angle is read out in parallel by the read address generation circuit 20. At this time, since the image memory to which the image data is written is also in the read mode during the period in which the write permission signal is not output, the image data is read out in the same manner as other image memories. Each image data is then given to the data output selection circuit 22. The data output selection circuit 22 has a fixed cycle (for example, 0.3 seconds) that is asynchronous with the writing/reading timing of the image memories 12a-12n and is neither too fast nor too slow for the human eye.
A switching pulse is applied, and in response to this switching pulse, image data read out in parallel from the image memories 12a to 12n is sequentially selected and output. As a result, as shown in FIG.
→ 34 → 36° → 24° → 26°... Images of a school of fish obtained by changing the angle sequentially are displayed, switching sequentially every 0.3 seconds. Therefore, the distribution of fish schools at each depth can be grasped three-dimensionally.

In this embodiment, the image memories 12a to 12 are activated in synchronization with the vibration transmission trigger pulse output from the elevation angle control circuit 8.
n is selected, but by switching the elevation angle within one period of the transmission trigger pulse and storing the image data obtained for each elevation angle in the image memory, a display similar to the above can be obtained. It is also possible.

<Effects of the Invention> According to the present invention, images of a school of fish are switched and displayed at regular time intervals as if viewing a moving image. Therefore, excellent effects such as being able to easily grasp the distribution of fish schools in three dimensions without being affected by the length of the transmission/reception period of the ultrasonic beam are exhibited.

[Brief explanation of the drawing]

1 and 2 show an embodiment of the present invention, and FIG. 1 is a block diagram including a scanning sonar image display device;
FIG. 2 is an explanatory diagram showing a display example of an image obtained by changing the elevation angle over time, and FIG. 3 is an explanatory diagram when the fish school distribution is investigated by changing the elevation angle. l... Transducer/receiver, 8... Elevation angle control circuit, 12a~
12n... Image memory, 16... Image memory selection means, 22... Data output selection circuit.

Claims (1)

[Claims] (1) An image display device installed in a scanning sonar equipped with an elevation angle control circuit that sequentially changes the elevation angle of an ultrasonic beam output from a transducer, the ultrasonic beam obtained by the transducer The image memory includes a plurality of image memories that store received signals of as image data, and sequentially selects an image memory into which image data is to be written from among the plurality of image memories in synchronization with switching of the elevation angle by the elevation angle control circuit. memory selection means; and a data output selection circuit that sequentially selects and outputs each image data corresponding to the elevation angle read out in parallel from each of the image memories at a constant cycle asynchronously with the writing/reading operation of the image memory. A scanning sonar image display device characterized by: