JPS62191784A - Method and apparatus for detecting and discriminating underwater article - Google Patents

Abstract

PURPOSE:To obtain the highly accurate information or an underwater article, by converting a reference clock pulse to an ultrasonic wave to receive the same and displaying the presence and shape of the underwater article on the basis of the phase information of an electric signals relating to a receiving echo and a reference clock. CONSTITUTION:The transmission clock signal generated from a clock signal generating circuit 10 is amplified by a power amplifying circuit 12 to be introduced into a transmitter-receiver 14 and the generated ultrasonic pulse is emitted into water while the reflected echo from a school of fish is converted to an electric signal to be introduced into an envelope detection circuit 22 and a phase detection circuit 24 through a preamplifier 16, BPF 18 and an amplifying circuit 20. In the circuit 24, the transmission clock signal generated from the clock signal generating circuit 10 is sifted in its phase by a phase shifter circuit 28 to be outputted to an exclusive OR circuit 30. The signal from the circuit 20 is converted from a sine wave to a rectangular wave by the circuit 30 to be sent to an exclusive OR circuit 32 to exclusive-OR the reference clock signal with the rectangular wave and the phase information of the school of fish is displayed on a display device 26 through LPF 34. In the circuit 22, the signal from the circuit 20 is processed by a full-wave rectifier circuit 36 and displayed on the display device 26 as the envelope information of the school of fish through LPF 38.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for detecting and identifying the presence of schools of fish using ultrasonic pulses, and more specifically, the present invention relates to a method and apparatus for detecting and determining the presence of schools of fish, etc. using ultrasonic pulses, and more specifically, the present invention relates to a method and apparatus for detecting and determining the presence of schools of fish, etc. The present invention relates to a method and device for detecting and identifying underwater objects that enable accurate detection and determination of underwater objects such as schools of fish by performing phase detection and using the phase information.

Underwater acoustic equipment has been widely used to confirm what exists underwater. A good example of this would be a fish finder. This fish finder transmits directional ultrasonic pulses into the water, and confirms the presence of a school of fish by the echoes reflected from the school of fish. That is, by focusing on the fact that the intensity of reflected echoes from underwater objects such as schools of fish is proportional to the size of the schools of fish, envelope detection is performed on the reflected echoes, and the amplitude of the signal wave is displayed in shading on recording paper. The presence of schools of fish is confirmed by color display on cathode ray tubes, etc. Of course,
In the case of a school of small fish or an underwater object with little reflection, this conventional method using envelope line detection has difficulty in accurately understanding the shape of the school of fish, etc., even if it is possible to determine the presence or absence of the school of fish. . Furthermore, when trying to detect a school of fish swimming on the bottom of a deep ocean floor, etc., the level of the reflected echo of the transmitted ultrasonic wave is low, making it impossible to distinguish it from the reflected echo from the ocean floor, etc. In the end, it has been pointed out that the disadvantage is that it is impossible to confirm the existence of the fish school itself.

The present invention has been made to overcome the various disadvantages mentioned above, and it detects the phase of received echoes of ultrasonic waves emitted underwater, and uses phase information of the reflected echoes to detect the presence of underwater objects such as schools of fish, etc. It is an object of the present invention to provide a method and device for detecting and determining underwater objects that can accurately confirm the shape and can be easily handled.

In order to achieve the above object, the present invention converts a predetermined reference clock pulse into an ultrasonic pulse and transmits it into the water, and converts an electric signal related to a received echo reflected by an object existing in the water and the reference clock into an ultrasonic pulse. It is characterized in that phase information is obtained from the electrical signal related to the pulse, and based on this phase information, the presence or absence of underwater objects and their shape are displayed.

Furthermore, the present invention includes a transmitter that converts a clock signal generated by a reference clock generation circuit into an ultrasonic signal and transmits it underwater, and a transmitter that receives an ultrasonic reflected signal reflected by an underwater object and converts it into an electric signal. a wave receiver; a phase detection circuit connected to the output side of the wave receiver to obtain phase information of an electric signal based on a reflected signal received with the clock signal as a reference; and connected to the output side of the phase detection circuit. and a display that displays the shape of underwater objects based on phase information.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, preferred embodiments of the underwater object detection/discrimination method according to the present invention in relation to an apparatus for carrying out the method will be described in detail with reference to the accompanying drawings.

First, the relationship between phase information and envelope information of reflected echoes from underwater objects such as schools of fish used in the present invention will be briefly explained.

For example, ultrasonic pulses emitted from a fish finder reach underwater objects such as schools of fish and are reflected by them. Therefore, the instantaneous value t of this reflected echo includes envelope information -P- and phase information θ as a signal that changes momentarily. This envelope information -P- and phase information θ are given by the following equation.

P, -Psin(ωt+θ) -(1)・
...(2) Here, p ri is the envelope of the reflected echo from target i that exists within the pulse width, φ positive is the initial phase of the transmitted wave of target i relative to the carrier, and ω is the angular frequency of the transmitted wave shows.

The present invention has been made with particular attention to the fact that the instantaneous value t of the reflected echo includes phase information expressed by equation (3).

Therefore, the configuration of the apparatus of the present invention will be explained below with reference to the drawings.

In FIG. 1, reference numeral 10 indicates a transmission clock generation circuit, one output side of which is connected to a power amplification circuit 12. The output side of the power amplifier circuit 12 is connected to a transducer 14 . The output side of the transducer 14 is connected to a preamplifier circuit 16, and the output side of the preamplifier circuit 16 is connected to a filter circuit, essentially a bandpass filter circuit 18. The output side of the filter circuit 18 is further connected to an amplifier circuit 20, and this amplifier circuit 20
One output terminal of the amplifier circuit 20 is connected to an envelope detection circuit 22, and the other output terminal of the amplifier circuit 20 is connected to a phase detection circuit 24.
It is connected to the. The output sides of the envelope detection circuit 22 and the phase detection circuit 24 are connected to a display 26, respectively. In addition,
The other output side of the transmission clock generation circuit 10 is a phase shift circuit 2.
8, and the output side of this phase shift circuit 28 is connected to the phase detection circuit 24. In this case, the phase detection circuit 24 is composed of a zero-cross detection circuit 30, an exclusive OR circuit 32, and a low-pass filter 34, and the output side of the amplifier circuit 20 is connected to the zero-cross detection circuit 30.
It is connected to a rectifier circuit 36 that branches out and forms the envelope detection circuit 22. The output side of this rectifier circuit 36 is further connected to a low-pass filter 38, and the output side of this filter 38 is connected to a display 26 for displaying envelope line information.
is connected to.

On the other hand, the output side of the phase shift circuit 28 is connected to the other input terminal of the exclusive OR circuit 32 constituting the phase detection circuit 24.

Next, the operation of the underwater object detection and discrimination device employing the above configuration will be explained.

First, the transmission clock signal (see Fig. 2g) generated by the transmission clock generation circuit 10 is gated to an appropriate width, sent as a transmission pulse to the power amplifier circuit 12, where it is power amplified, and then transmitted and received. It is introduced into the wave device 14. This transducer 14 generates ultrasonic pulses in synchronization with the transmission clock frequency, and emits them into the water. If there is a school of fish underwater, the ultrasonic pulse is reflected by the school of fish, and the reflected echo is transmitted to the transducer 14.
received at In this transducer 14, the ultrasonic pulse related to the reflected echo is converted into an electrical signal to become a received echo signal, which is introduced into the preamplifier circuit 16. This preamplifier circuit 16 preamplifies the received echo to an appropriate level for proper filtering in the bandpass filter circuit 18 at the next stage. Needless to say, the filter circuit 18
Then, extract only the signals in the necessary band. Filter circuit 1
The reflected signal from the school of fish whose band is limited by 8 is transmitted to an amplifier circuit 20.
is amplified to the level required to be displayed on the display (
(See Figure 2C) Envelope detection circuit 22 and phase detection circuit 24
will be introduced. The phase detection circuit 24 converts the transmission clock signal generated by the transmission clock generation circuit 10 into the phase shift circuit 2.
At step 8, the signal is phase-shifted by an appropriate phase φ to become a reference clock signal (see FIG. 2), and sent to the exclusive OR circuit 32. On the other hand, the signal from the amplifier circuit 20 is converted from a sine wave to a rectangular wave by the zero cross detection circuit 30 (see Fig. 2C).
) is sent to the exclusive OR circuit 32. This exclusive OR circuit 32 performs an exclusive OR of the reference clock signal and the rectangular wave (see FIG. 2C), detects the phase difference between the two, and sends it to the low-pass filter 34. The filter 34 converts the phase difference signal into a DC signal (see FIG. 2C).
, to the display 26 to display the phase information of the fish school.

On the other hand, in the envelope detection circuit 22, the signal from the amplifier circuit 20 is full-wave rectified by a rectifier circuit 36 (see FIG. 2g) and sent to a low-pass filter 38. Low pass filter 38
Then, the rectified pulsating current signal is smoothed and sent as a DC signal to the display 26 (see second diagram) to display envelope information of the fish school.

If the reflection level from a school of fish or the like is low and the signal is smaller than the displayable threshold level (see FIG. 2C), the envelope information will not be displayed as a signal.

Note that the phase of the phase information changes when a reflective object such as a school of fish is present, regardless of the reflection level. Therefore, phase emotion! The signal becomes larger than the threshold level i (see Figure 2C) and is clearly displayed as a reflected signal from a school of fish.

FIG. 3 shows an example of the display form of the display 26. The upper half 26a of the display 26 shows envelope information of reflected echoes from underwater objects such as schools of fish. In this case, reference numeral 40
a, 42a represents the presence of a school of fish, etc., and reference numeral 44
Figure a shows the shape of the shelf on the ocean floor.

On the other hand, in the lower half 26b of the display 26, reference numeral 40b
, 42b indicates phase information of reflected echoes emitted from schools of fish, etc., and reference numeral 44b indicates the presence of a shelf portion on the seabed in this case. Particularly in the lower half 26b of this display 26, the presence of a fish shadow indicated by the reference numeral 46 should be noted. That is, the upper half 26a
In this case, this fish shadow 46.46 is displayed as if it is a part of the shelf portion 44a, but by using phase information, it is possible to distinguish the rooted fish shadow 46.46 on the shelf portion 44b along with its shape. be.

According to the present invention, as described above, phase information is obtained using ultrasonic pulses emitted to underwater objects such as schools of fish, and thereby the existence and shape of the underwater objects can be clearly understood. It consists of According to the conventional technology, in the case of a school of small fish or an underwater object with little reflection, it was only possible to identify the presence or absence of an underwater object because the discrimination was based only on envelope information, but the method and device of the present invention Accordingly, it is possible to grasp not only the presence of the underwater object but also its shape. This makes it possible to determine, for example, what fishing method a fishing boat should adopt, or whether it is possible to select a course for the boat.

Moreover, according to the present invention, envelope information and phase information are displayed on the same display. In this case, the size of the object underwater is displayed in proportion to the amplitude of the envelope;
The phase information gives an indication of its shape as well as its detection ability. Therefore, there is an advantage that the size and shape of a school of fish etc. can be displayed by using both the envelope information and the phase information together.

Furthermore, displaying envelope route information has the advantage that schools of fish can be further identified using the know-how accumulated over many years by fishermen. It goes without saying that it is possible to perform correlation processing on the envelope information and phase information and display the result as a single image.

Furthermore, according to the present invention, unlike the conventional technology that uses only envelope information, it is possible to clearly grasp rooted fish schools, etc., so that even more accurate information on underwater objects can be obtained. There are also advantages.

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

[Brief explanation of drawings]

FIG. 1 is a block circuit diagram of a device for implementing the method for detecting and determining underwater objects such as schools of fish using phase information and envelope information according to the present invention; FIG. 2 is a waveform diagram of each part of the circuit of the device; FIG. 3 is a schematic explanatory diagram showing an image of envelope line information and phase information displayed by the display shown in FIG. 1. DESCRIPTION OF SYMBOLS 10... Transmission clock generation circuit 12... Power amplifier circuit 14... Transmitter/receiver 16... Preamplifier circuit 18... Band pass filter circuit 20... Amplifier circuit 22... Envelope Detection circuit 24... Phase detection circuit 26... Display 28... Phase shift circuit 30... Zero cross detection circuit 32... Exclusive OR circuit 34... Low pass filter 36... Rectifier circuit 38 ...low bass filter

Claims (3)

[Claims] (1) A predetermined reference clock pulse is converted into an ultrasonic pulse and transmitted underwater, and phase information is obtained from an electrical signal related to a received echo reflected by an object existing in the water and an electrical signal related to the reference clock pulse. An underwater object detection and discrimination method characterized in that the presence or absence of an underwater object and its shape are displayed based on this phase information. (2) A transmitter that converts the clock signal generated by the reference clock generation circuit into an ultrasonic signal and transmits it underwater, and a receiver that receives the ultrasonic reflected signal reflected by underwater objects and converts it into an electrical signal. a phase detection circuit connected to the output side of the wave receiver to obtain phase information of an electrical signal based on a reflected signal received with the clock signal as a reference; What is claimed is: 1. An underwater object detection and discrimination device comprising: a display device that displays the shape of an underwater object based on information; (3) In the apparatus according to claim 2, an underwater object is configured such that an envelope detection circuit is connected in parallel to the phase detection circuit, and both envelope information and phase information are displayed on the display. Detection and discrimination device.