JPH01118791A - Signal processor of ultrasonic sonar - Google Patents

Abstract

PURPOSE:To accurately decide an echo signal by providing an address correcting means based upon the swivel angle of a vibrator and specifying the same direction and the same address position for the echo signal of a distance without depending upon variation in the swivel angle. CONSTITUTION:The vibrator 2 is positioned at a desired swivel angle and an elevation angle and sends an ultrasonic wave signal and then when it is switched to reception, the vibrator is switched at a high speed to receive the echo signal while the azimuth is converted. A direction counter 22 counts up in synchronism with the switching of the azimuth and every time the counter 22 counts up by one round, a distance counter 24 counts up. Here, when the swivel angle of the vibrator 2 is changed clockwise by a fine angle at the time of next transmission, an echo signal from a body which is a body in the azimuth and at the distance where the echo is received in transmission is received in an azimuth deviating counterclockwise by a quantity corresponding to the fine angle. Then a deviation in the counted value of the counter 22 corresponding to the fine angle can be corrected.

Description

Detailed Description of the Invention [Industrial Application Field 1] The present invention relates to a signal processing device for an ultrasonic sonar that transmits and receives ultrasonic waves to determine and detect the presence of schools of fish in the sea. When receiving the echo signal of the ultrasound transmitted from the transducer and displaying the image, in order to remove interference waves from other sonar etc. and obtain a precise image, the direction of the echo signal with respect to the ultrasound transmitted from the transducer and the The present invention relates to a signal processing device in an ultrasonic sonar configured to remove the influence of interference waves by accurately comparing echo signals at the same point in previous transmission and current transmission based on distance.

[Background of the Invention] Conventionally, underwater acoustic equipment has been widely used to confirm objects existing underwater. An ultrasonic sonar device can be cited as a suitable example. Ultrasonic sonar devices emit sound waves, especially ultrasonic pulses, over a wide range of water from a transducer consisting of a large number of transducers arranged in a cylindrical or arc shape, or direct them by combining multiple transducers. Underwater detection involves forming a receiving beam with a unique characteristic, and rotating this receiving beam by sequentially switching the combination of transducers to receive echo signals, that is, reflected waves, returning from each direction and displaying them on a cathode ray tube. It is a device. In other words, focusing on the fact that the intensity of reflected echoes from underwater objects such as schools of fish is generally proportional to the size of the schools of fish, the amplitude of the signal waves related to the reflected echoes is displayed in color on a display such as a CRT or on recording paper. The presence of schools of fish, etc. can be identified and confirmed by displaying shading.

There are various types of ultrasonic sonar, and depending on the display method, there are recording sonar that displays the echo of the object on recording paper, and PPI sonar that displays the echo of an object on a CRT (cathode ray tube).
Display (Plan Po5itionIndicator
) can be broadly classified into PPI sonar.

In this case, PPI sonar is classified into searchlight type and scanning type based on the difference in scanning method.

Regardless of the method, basically a transducer is positioned with a desired turning angle and depression angle, an ultrasonic signal is transmitted from the transducer, and an echo signal is generated when this ultrasonic signal is reflected by an object. The position of the object is determined or confirmed by receiving the echo signal and displaying the echo signal according to its direction and distance.For example, in the case of a half-circle scanning sonar, the configuration is roughly shown in Figure 1. We are hiring.

In FIG. 1, reference numeral 2 is a transducer for transmitting ultrasonic signals or receiving echo signals from an object,
Each motor of the drive section 6 operates based on control signals from the control circuit 4, and is positioned at a desired turning angle and depression angle. The transducer 2 is composed of a large number of transducers arranged on the circumference of a cylindrical body, and as shown in the phase tropism during transmission in Fig. With sonar, powerful ultrasonic pulses are emitted simultaneously in each direction (over the entire circumference), and as shown in the receiving directivity in Figure 3, several transducers are sequentially combined according to each direction during reception. It switches and scans at high speed to create a narrow directional beam area in one direction, thereby receiving echo signals from objects.

The transmitter/receiver section 8 selects and drives the vibrator 2 so as to perform the above-mentioned transmission according to the transmission pulse from the control circuit 4, and to perform the above-mentioned reception according to the reception direction signal.

Each time an ultrasonic signal is transmitted from the transducer 2 using such a transmission/reception method, the transmitter/receiver 8 obtains an echo signal corresponding to each direction and distance in the water almost instantaneously over a half-circle, and transmits this signal to the A/ After A/D conversion is performed in the D converter 10 and predetermined signal processing is performed in the signal processing device 12, the signal is displayed on a display unit 14 such as a CRT cathode ray tube. That is, the echo signal is displayed as an image according to its direction and distance.

The signal processing device 12 generally performs correlation processing and filter processing in order to remove interference waves from other sonar or the like and to smooth images. Here, interference wave removal will be described as an example of signal processing according to the present invention.

This interference wave is mainly ultrasonic waves from other sonar, and is not synchronized with the periodic transmission timing of the sonar itself. Therefore, interference waves occur in different directions and distances for each transmission. Therefore, the echo signals of the ultrasound transmitted at each point in time are compared at the same direction and distance, and if an echo signal is present each time, it is not determined to be an interference wave, and the echo signal is not present at the previous transmission and is transmitted this time. If an echo signal is present only occasionally, it can be determined to be an interference wave, and if it is determined to be an interference wave, it can be removed from the image and not displayed.

For this reason, the signal processing device 12 converts the echo signal into its direction and direction.
It has a storage means (memory) 20 for storing an address signal according to the distance, and the echo signal in the current transmission in the same direction and distance is stored in the azimuth counter 2 from the memory 20.
2) A comparison circuit 26 is provided to compare the previous echo signal stored at the address position determined by the address generation means 30 constituted by the distance counter 24, and if the comparison results match, it is determined that the echo signal in the current transmission is normal. The echo signal is sent to the display section 14 via the gate circuit 28 and displayed, and is also stored at an address location in the memory 20 determined by the address generating means 30.

The azimuth counter 22 constituting the address generating means 30 is reset by the azimuth reference signal, and sequentially counts up according to the direction (azimuth) of the received beam by the clock signal.The distance counter 24 is reset by the transmission trigger, and the count value of the azimuth counter 22 is incremented by the clock signal. The count is sequentially incremented each time the number reaches a half-circumference bone (in the case of a full-circle type sonar, each time it corresponds to a complete circumference, that is, one full circle). The direction reference signal is output, for example, when the reception direction is switched to the left end of the vibrator.

The signal processing device 12 for removing interference waves in ultrasonic sonar is configured to perform the operations described above. However, the above configuration causes the following disadvantages.

That is, the relationship between the vibrator 2 and the object M is expressed in polar coordinates (A) with the vibrator 2 at the center, as shown in FIG.

r), (A+1.r), (A, r+1), (A+1゜r
When there is an object M represented by +1), the echo signal is written at the address position determined by the direction and distance. It will be α.

When the transducer 2 changes from the state shown in FIG. 4 to the next ultrasonic transmission,
As shown in FIG. 5, if we consider the case of turning to the right by the turning angle Δθ, the azimuth counter 22 counts up based on the left end of the transducer. This time for M, that is,
The storage position of the echo signal when the vehicle turns to the right by the turning angle Δθ is stored at an address position shifted to the left by an amount corresponding to the turning angle Δθ, as shown in FIG. Therefore, the previous echo signal in the same direction and distance as the current echo signal cannot be read from the same storage location, and even though the object M exists and a normal echo signal is being received, it is treated as an interference wave. The display section 14
This results in the inconvenience that the image is no longer displayed.

[Object of the Invention] The present invention has been made to overcome the above-mentioned disadvantages, and even when the vibrator rotates as described above,
To provide a signal processing device in an ultrasonic sonar that can control address generation means so that echo signals in the same direction and distance are always stored in the same storage position of a storage means, and can accurately determine or confirm echo signals. With the goal.

[Means for Achieving the Object] In order to achieve the above object, the present invention positions a transducer with a desired turning angle and depression angle, and transmits an ultrasonic signal by the transducer or generates an echo signal from an object. storage means for receiving the echo signal and storing the echo signal in an address position generated by the address generation means based on the direction and distance; and an echo signal for the previous transmission signal in the same direction and distance as the echo signal for the current transmission signal. and calculating means for reading out and calculating from the storage means, and transmitting the result calculated by the calculating means to a display section to display an image of the object based on the echo signal, and to display an image of the object based on the echo signal corresponding to the current transmission signal. a signal processing device for an ultrasonic sonar, the signal processing device storing in an address position generated from the address generating means, the signal processing device correcting the address generated from the address generating means based on the turning angle of the transducer. The present invention is characterized in that the present invention is characterized in that an address correction means is provided to specify the same address position for echo signals in the same direction and distance regardless of the change in the turning angle.

Embodiment 1 Next, a preferred embodiment of the signal processing device for an ultrasonic sonar according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 7 is a schematic configuration diagram showing an example of a signal processing device in an ultrasonic sonar according to the present invention.

In FIG. 7, reference numeral 20 is a storage means for storing echo signals, and reference numeral 30 is an address generation means for generating an address signal specifying an address position of the storage means 20 according to the direction and distance of the echo signal. As in Figure 1, the azimuth counter 22 is reset by the azimuth reference signal (generated with the left end of the vibrator as a reference) and counts up by the clock signal, and the azimuth counter 22 is reset by the transmission trigger and counts up for one round. It is composed of a distance counter 24 that counts up based on a signal generated every time.

Reference numeral 32 is an address correction means, which converts the azimuth address created by the azimuth counter 22 into the turning angle Δθ of the vibrator 2.
The address generating means 30 is controlled so that the echo signals of the same direction and the same distance are stored in the same position on the storage means 20.

The signal processing device according to the present invention is basically constructed as described above, and its operation and effects will be explained next.

First, in FIG. 1, the transducer 2 is positioned at a desired turning angle and depression angle, and an ultrasonic signal is transmitted. Then, when switching to reception, the cylindrical transducer is switched at high speed as described above, and the azimuth is sequentially determined. receive echo signals while displacing the The azimuth counter 22 counts up in synchronization with this switching of the azimuth, and the distance counter 24 counts up every time the azimuth counter 22 counts one revolution. Therefore, when an echo signal is received at a certain azimuth and distance, the azimuth counter 22) and distance counter 24 at that point become the address position of the memory 20, and the echo signal is stored at the address position.

Here, at the time of the next transmission, if the turning angle of the transducer 2 is turned to the right by Δθ as shown in FIG. As shown in FIG. 6, the echo signal from the vehicle is received from an azimuth shifted to the left by an amount corresponding to the turning angle Δθ. That is, the value of the azimuth counter 22 when receiving the echo signal is shifted to the left by an amount corresponding to Δθ.

Therefore, the address correction means 32 adjusts the orientation counter 2.
By correcting the count value of 2 and shifting it to the right by an amount corresponding to the turning angle Δθ, it is possible to make the storage positions of the echo signal in the previous transmission and the echo signal in the current transmission the same. Specifically, the address correction means 32 can be configured with an addition circuit, and when the turning angle of the vibrator 2 is divided into n+1 equal parts per revolution, (n+
1) By configuring the addition in a base system, it is possible to correct the deviation in the count value of the azimuth counter 22 corresponding to the turning angle Δθ. Alternatively, the address can be corrected by resetting the azimuth counter 22 earlier by an amount corresponding to the turning angle Δθ.

FIG. 8 is a schematic configuration diagram of a signal processing device showing this embodiment, in which a delay circuit is inserted as an address correction means 32 on the reset side of the azimuth counter 22 that inputs the azimuth reference signal, and (360° - turning angle) By delaying the azimuth reference signal by a corresponding amount and resetting the azimuth counter 22, it is possible to correct the address deviation (azimuth deviation) due to the turning angle Δθ.

The above explanation assumes that the depression angle of the vibrator 2 is around 0°, that is,
This is an explanation of a case where ultrasonic waves are transmitted in a direction close to horizontal to search for the presence of an object in a horizontal plane. When searching for images or objects such as schools of fish that have landed on the ocean floor, the following problems will occur if the address correction based on the turning angle is performed as described above.

In other words, as shown in Fig. 9, when the angle of depression of the transducer 2 is selected to be close to 90°, the phase direction during transmission and the plane in which the echo signal rotates during reception are the same plane, and the image based on the echo signal on the sea floor is As shown in FIG. 10, the echo signal is displayed as a horizontally linear image at a distance equivalent to the water depth, and the echo signal is stored in the memory 20 in the same form as this image. When the vibrator 2 is rotated while keeping its depression angle close to 90°, the rotation is performed around the vertical axis as shown in FIG.
A flat seabed is received in the same shape even when turning, but if the address in the memory 20 is shifted by the turning angle Δθ by the address correction means 32 described above, an echo of the rotation before turning as shown in FIG. The address position on the memory 20 of the echo signal after turning with the signal will be shifted, and only the location where both echo signals intersect, that is, the location where both echo signals match, will be stored and displayed as a normal image.
Other areas of mismatch will be removed as interference waves.

FIG. 12 shows an example of a signal processing device configured to solve this problem, and the address correction means 32 in FIG.
an addition circuit 42 that adds the correction bone to the count value of the azimuth counter 22 according to the rotation angle of the transducer;
and a switching means 44 for switching between validating and invalidating the address correction by. That is, the switching means 44 changes the depression angle to O depending on the depression angle of the vibrator 2.
When the depression angle is near 90° (horizontal), connect the switch SWl to the addition circuit 42 side to enable address correction, and when the depression angle is near 90° (vertical), connect the switch SWI to the azimuth counter 22 side to disable address correction. It operates in such a way that it becomes This switching means 44 makes it possible to solve the above-mentioned problem when the depression angle of the vibrator 2 is positioned near 90 degrees.

FIG. 13 is a diagram showing another configuration of a signal processing device equipped with the switching means 44. In the signal processing device shown in FIG. 12 described above, when the switching means 44 switches the addition circuit 42 that adds the correction value according to the azimuth counter 22 and the turning angle Δθ, the address position of the memory 20 changes rapidly by the number of turns. do.

In order to prevent this, the signal processing device shown in FIG.
A switch SW2 formed by a switching means is provided between this variation extraction circuit 46 and an accumulator 48, and the output of the accumulator 48 is configured to determine the added value of the adder circuit 42 for address correction. ing. When correcting the address according to the turning angle when the depression angle of the transducer 2 is near 0°, the switch SW2 is closed by the switching means 44, the turning angle of the transducer 2 is inputted to the change extraction circuit 46, and the turning angle is The address is corrected by calculating only the change in , accumulating the change in an accumulator 48 , and adding the result to the count value of the azimuth counter 22 in an adder circuit 42 . When the depression angle of the vibrator 2 is close to 90' and there is no need to correct the address due to the turning angle, the switching means 44 opens the switch SW2 to set the human power of the accumulator 48 to 0 so that its output does not change. and the count value of the azimuth counter 22 is added to the adder circuit 4.
Step 2 prevents you from receiving corrections.

Next, when the depression angle of the vibrator 2 becomes close to 0° and it becomes necessary to correct the address again, switch SW2
is closed, and the accumulator 48 is added to the turning angle change extraction circuit 46.
When the input of the accumulator 48 is connected, the contents of the accumulator 48 immediately before it change by the change in the turning angle, and that amount is added to the count value of the azimuth counter 22 via the adding circuit 42, and the address is corrected. Discontinuity (rapid change) in the address position on the memory 20 due to switching of the switching means 44
can be eliminated.

In the embodiments shown in FIGS. 12 and 13, the specific means for correcting the address has been explained using the addition circuit 42, but the address correction means 32 as a delay circuit shown in FIG.
Even if a method is adopted in which the azimuth reference signal, which is the reset timing of the azimuth counter 22, is delayed according to the turning angle, and the reset timing of the azimuth counter 22 is shifted, the switching means 44, the change extraction circuit 46, and the cumulative Calculator 4
8 can be provided to provide the same functions as those in FIGS. 12 and 13.

[Effects of the Invention] As explained above, the signal processing device for the ultrasonic sonar according to the present invention positions the transducer at a desired turning angle and depression angle, receives an echo signal from an object, and converts the echo signal into the A storage means for storing an address position generated by the address generation means based on the azimuth distance, and an echo signal for the current transmission signal and an echo signal for the previous transmission signal in the same direction and distance are read from the storage means and compared. and when a match is detected in the comparison means, the echo signal corresponding to the current transmission signal is stored as valid at the address position generated by the address generation means, and is sent to the display section to display the echo signal. Displays an image of the object based on the signal,
When a mismatch is detected, the echo signal for the current transmission signal is invalidated as an interference wave, and the address generated by the address generation means is corrected based on the rotation angle of the vibrator. An address correction means is provided so that the same address position is specified for echo signals of the same direction and distance regardless of a change in the turning angle. The apparatus is configured to include a switching means for enabling or disabling the correction means.

Therefore, even when the transducer rotates, it is possible to always compare echo signals in the same direction and distance, and since it is possible to accurately judge and confirm echo signals, interference waves can be removed correctly. It has the advantage of

In addition, it is possible to enable or disable the function that corrects the address according to the angle of depression of the transducer, and automatically switches whether or not to correct the address for horizontal and vertical transmission. It also has the advantage of being easy to operate.

The above has been explained using an example of removing interference waves, but in addition to removing interference waves, processing such as simple averaging or weighted averaging of the current echo signal and the previous echo signal stored in memory is also possible. It is clear that the same effect will be produced when the method is used.

Although the present invention has been described above with reference to preferred embodiments, the present invention is not limited to these embodiments.
Of course, various improvements and changes in design are possible without departing from the gist of the present invention.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of an ultrasonic sonar to which a signal processing device according to the present invention is applied, FIG. 2 is an explanatory diagram showing directivity during transmission, and FIG. 3 is an explanatory diagram showing I directionality during reception. , Fig. 4 is an explanatory diagram showing the positional relationship between the transducer and the object, Fig. 5 is an explanatory diagram showing the rotating state of the transducer, and Fig. 6 is an explanatory diagram showing the storage position of the echo signal when the transducer rotates. 7 is a schematic configuration diagram showing an example of a signal processing device according to the present invention, FIG. 8 is a schematic configuration diagram showing another example of a signal processing device according to the present invention, and FIG. 9 is a depression angle of a vibrator. An explanatory diagram showing the transmitting and receiving beams when the angle of depression of the transducer is set near 90°. Figure 1O is an explanatory diagram showing the echo signal on the sea floor when the depression angle of the transducer is set near 90°. Turning angle Δ while maintaining the depression angle of
An explanatory diagram showing an echo signal on the seabed when the transducer rotates by θ; FIG. 12 is a schematic configuration diagram of a signal processing device equipped with a switching means for enabling and disabling the address correction means according to the depression angle of the transducer; FIG. 13 is a schematic configuration diagram showing another example of a signal processing device equipped with switching means. 2... Vibrator 4... Control circuit 6...
Drive section 8... Transmission/reception section 10... A/D
Conversion unit 2...Signal processing device 14...Display unit 20...Storage means 22...Direction counter 24...Distance counter 26...Comparison means
28...Gate circuit 30...Address generation means 32...Address correction means 42...Addition circuit 44...Switching means 46...Change extraction circuit 48...Accumulator FIG, 2
FIG, 3 comparison times jl & to comparison lnl path previous submarine signal

Claims (3)

[Claims] (1) Position a transducer with a desired turning angle and depression angle, transmit an ultrasonic signal with the transducer, or receive an echo signal from an object, and transmit the echo signal from the address generation means based on its direction and distance. a storage means for storing the echo signal at a generated address position; and a calculation means for reading out from the storage means an echo signal for the previous transmission signal in the same direction and distance as the echo signal for the current transmission signal, and calculating the echo signal for the previous transmission signal, the calculation means In an ultrasonic sonar, the calculated result is sent to a display unit to display an image of the object based on the echo signal, and the echo signal corresponding to the current transmission signal is stored in the address position generated by the address generation means. The signal processing device is provided with an address correction means for correcting the address generated by the address generation means based on the turning angle of the vibrator, and the signal processing device is provided with an address correction means for correcting the address generated by the address generation means based on the turning angle of the vibrator. 1. A signal processing device for an ultrasonic sonar, characterized in that the same address position is specified for distance echo signals. (2) In the device according to claim 1, the address correction means is an ultrasonic sonar comprising a switching means for enabling or disabling the address correction means according to the depression angle of the transducer. signal processing device. (3) In the apparatus according to claim 2, the address correction means includes a change extraction circuit that extracts a change in the rotation angle of the vibrator, and an accumulation circuit that accumulates the change in the rotation angle. A signal processing device for an ultrasonic sonar, comprising: a signal processing device for an ultrasonic sonar, the switching device controlling whether or not the output of the change extraction circuit is input to the accumulator.