JPH0587925A - Active sonar apparatus - Google Patents

Abstract

PURPOSE:To obtain an active sonar apparatus enabling correct display of the distance. CONSTITUTION:In an active sonar apparatus designed to send acoustic signals with a predetermined time difference TD in each of many directions (e.g. five directions), beam generating circuits 6 form receiving beams of the same five directions as at the transmitting side when the circuits receive the signals of the reflecting echoes from the five directions sequentially detected by a wave detector 4 via an amplifier 5. Receiving signals are formed of the receiving beams. The sweep reference to control the display is the timing of the last transmitting signal (beam 5). Therefore, each receiving signal is delayed by the corresponding transmitting time difference on the basis of the last transmitting signal (0, TD, 2TD, 3TD, 4TD) as a reference in a delay circuit 7 and then fed to a target detecting circuit 8. Consequently, the display device sweeps each receiving signal while using the same reference time. Accordingly, the reflecting echoes from the same distance are correctly displayed at the same position even when any of the receiving beams are used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active sonar device for receiving and processing reflected echoes of acoustic signals sequentially transmitted with a time difference in each direction of multiple directions and detecting and displaying a target, and more particularly to an active sonar device. Receiving processing technology.

[0002]

2. Description of the Related Art In an active sonar apparatus for searching a wide range of targets, for example, as shown in FIG. 3, a transmission controller 3 determines, for example, five transmitted beams (beam 1 to beam 5) having different directions in this order. The transmitter 2 is provided with a transmission signal to be formed with a time difference of, and the transmitter 2 excites the wave transmitter 1 in accordance with the transmission signal from the transmission controller 3 to generate a pulsed acoustic signal from the wave transmitter 1 in water. Sequentially transmitted in 5 directions, 5 in water
This is a device that receives reflected echoes from each direction by receiving waves formed in each direction, detects the presence of a target, and detects and displays the distance and direction.

By the way, in this type of active sonar device, display control on the display is performed as shown in FIG. That is, FIG. 4A shows a case where five transmission signals are transmitted at the interval T _D (left end) and the presence of the target is detected in the reflection echo for the fifth transmission signal (center). The sweep operation of the display is performed based on the rising timing of the last transmission signal (fifth transmission signal) as shown in FIG.

[0004]

Then, in the conventional active sonar apparatus, since the reflected echoes received by each received beam are sequentially displayed as they are, a correct target other than the reflected echo for the last transmitted signal is obtained. There is a problem that the distance cannot be displayed.

That is, the display unit displays the reception time and the distance with the vertical axis as time and the horizontal axis as the target distance. For example, when the reflected echoes from the same distance are received by the respective receiving beams, the display unit shows Dots are displayed in order from beam 1. At this time,
Since the sweep of the display is performed with the beam 5 as a reference, the display positions of the beams 1 to 4 are predetermined positions near the origin from the display position of the beam 5. That is, although FIG. 4 (c) shows these overlapping, as shown in FIG.
The display position of is shorter than the actual distance. In terms of specific numerical values, the distance corresponding to the time of 4T _D is displayed short in beam 1, but since T _D is usually several hundred ms, a display error of about 600 m occurs.
As the number of transmitted signals increases, the display error becomes larger.

Further, when a plurality of targets are present at the same time, even if the distance display is not accurate and the distances are the same, the dispersed display is made as shown in FIG. There is also the problem that there is.

It is an object of the present invention to provide an active sonar device which enables correct distance display.

[0008]

In order to achieve the above object, the active sonar device of the present invention has the following constitution. That is, the active sonar device of the present invention is an active sonar device that performs reception processing of reflected echoes of acoustic signals sequentially transmitted with a time difference in each direction of multiple directions to detect and display a target; reflection from each direction A delay circuit for delaying the reception signals of the echoes by the transmission time difference based on the last transmission signal is provided.

[0009]

Next, the operation of the active sonar device of the present invention constructed as described above will be described. In the present invention, the received signals of the reflected echoes from the respective directions, that is, the signals after the received beams are generated, are delayed by the transmission time difference with respect to the last transmitted signal as a reference, and the target detection processing is performed on the delayed signals. To do.

As a result, the sweep start time of the display is the same for each received beam, so that reflected echoes from the same distance can be displayed at the same distance regardless of which received beam, and the correct distance can be displayed. .. When there are a plurality of targets at the same distance, the display area is larger than the display of the same target, and therefore it is easy to discriminate between the same target and a plurality of targets.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an active sonar device according to an embodiment of the present invention. In this active sonar device, a delay circuit 7 is provided between the beam generation circuit 6 and the target detection circuit 8.

The transmission controller 3 is, for example, as described above,
Five transmitted beams with different directions (beam 1 to beam 5)
Is transmitted to the transmitter 2 while forming a signal with a predetermined time difference in this order, while the transmission timing signal is supplied to the delay circuit 7, the target distance calculation circuit 9 and the display 11.

As a result, the transmitter 2 excites the wave transmitter 1 in accordance with the transmission signal from the transmission controller 3, and the pulse wave acoustic signal is sequentially transmitted from the wave transmitter 1 in five directions in water.

The reflected echoes from the five directions in the water are received by the wave receiver 4, and the received signals are input to the beam generation circuit 6 via the amplifier 5.

The beam generation circuit 6 receives the reception signals and generates five reception beams similar to those on the transmission side (FIG. 2), and gives the reception signals of the respective reception beams to the corresponding delay circuits of the delay circuit 7. (Figure 2).

The delay circuit 7 has a transmission timing shown in FIG.
In the case shown in (a), the delay time τ is τ = 0
, Τ = T _D , τ = 2T _D , τ = 3T _D , and τ = 4T _D. Medium, beam 1
The output is delayed by 4T _D , the beam 2 output is delayed by 3T _D , the beam 3 output is delayed by 2T _D ,
Beam 4 output is delayed by T _D and beam 5 is
Since the output is the same as the sweep reference time of the display 11, it is not delayed and is input to the target detection circuit 8 in order.

The target detection circuit 8 detects whether or not there is a reflection echo from the target for each input reception signal, and when the target exists, the target detection circuit 8 outputs the information to the target distance calculation circuit 9 and the image signal. It is given to the conversion circuit 10.

The target distance calculating circuit 9 adds the detected distance information to the display 11 by correcting the transmission / reception time. Further, the image signal conversion circuit 10 converts the received signal into an image signal and gives it to the display unit 11.

Here, the display 11 is the same as that described above (see FIG. 4).
As described in (b)), the sweep operation is performed based on the rising time point of the last transmission signal (fifth transmission signal), but the reception signal by each receiving beam is the transmission based on the last transmission signal. Since the delay corresponding to the time difference is delayed, the sweep operation for each reception signal is performed with the same reference time.

Therefore, reflected echoes from the same distance are correctly displayed at the same display position regardless of which received beam is received. When a plurality of targets exist at different distances, they are distributed and displayed as shown in FIG. 4C. On the other hand, when a plurality of targets exist at the same distance, the display area is larger than the display of the same target. Therefore, it is easy to discriminate between the same target and a plurality of targets.

[0021]

As described above, according to the active sonar apparatus of the present invention, the reception signals of the reflection echoes from the respective directions, that is, the signals after the reception beam is generated, are delayed by the transmission time difference. Since the sweep start time of the display is set to be the same for each received beam,
Reflected echoes from the same distance can be displayed at the same distance regardless of which received beam is received, and the correct distance can be displayed. When there are a plurality of targets at the same distance, the display area is larger than the display of the same target, so that it is easy to distinguish between the same target and a plurality of targets.

[Brief description of drawings]

FIG. 1 is a configuration block diagram of an active sonar device according to an embodiment of the present invention.

FIG. 2 is a detailed view of a main part (delay circuit) of the present invention.

FIG. 3 is an explanatory diagram of a transmission system that transmits acoustic signals in multiple directions.

4A is an explanatory diagram of transmission / reception timing, FIG. 4B is an explanatory diagram of a sweep reference time of a display device, and FIG. 4C is an explanatory diagram of a conventional display system.

[Explanation of symbols]

 1 wave transmitter 2 transmitter 3 transmission controller 4 wave receiver 5 amplifier 6 beam generation circuit 7 delay circuit 8 target detection circuit 9 target distance calculation circuit 10 image signal conversion circuit 11 indicator

Claims (1)

[Claims] 1. An active sonar device for receiving and processing reflected echoes of acoustic signals sequentially transmitted with a time difference in each direction of multiple directions to detect and display a target; received signals of reflected echoes from respective directions A delay circuit that delays the transmission time difference based on the last transmission signal respectively;
An active sonar device characterized by being provided with.