JPH0789146B2 - Underwater object detection and discrimination device - Google Patents

Description

The present invention relates to an apparatus for detecting and discriminating the presence of a school of fish or the like by using ultrasonic pulses, and more specifically, phase detection of a received echo of ultrasonic pulses emitted directed toward water. Then, the present invention relates to an underwater object detection / discrimination device capable of accurately detecting and discriminating underwater objects such as a school of fish by using the phase information.

BACKGROUND ART Conventionally, underwater acoustic equipment has been widely used to confirm what is present in water. A fish finder could be mentioned as a suitable example of this. This fish finder is for transmitting an ultrasonic pulse having directivity into water and for confirming the existence of the fish school by a reflection echo reflected from the fish school or the like. That is, focusing on the fact that the intensity of the reflection echo from an underwater object such as a school of fish is proportional to the size of the school of fish, envelope detection of the reflection echo is performed, and the amplitude of the signal wave is displayed on the recording paper as a gray scale, or The existence of fish schools is confirmed by displaying them in color on a cathode ray tube. However,
According to the envelope detection method of this conventional technique, in the case of a small school of fish or an underwater matter with few reflections, the shape (size, spread) of the school of fish can be accurately grasped even if the presence or absence of the school of fish can be determined. It was difficult. Furthermore, when trying to detect a school of fish swimming on the bottom of the sea, etc., the level of the echo waves reflected from the fish school of the transmitted ultrasonic waves is high, but the echo waves reflected from the sea bed directly below the school of fish are even more intense. It has been pointed out that there is an inconvenience that the reflected echo of the school of fish and the reflected echo of the sea bottom cannot be discriminated from each other and the existence of the school of fish itself cannot be confirmed after all.

The present invention has been made to overcome the above-mentioned various inconveniences, and phase-detects an electric signal (frequency is the same as an ultrasonic wave) related to a reflection echo of an ultrasonic wave generated in water,
An object of the present invention is to provide an underwater object detection / discrimination device capable of accurately confirming the presence and shape of underwater objects such as a school of fish based on the phase information of the reflected echoes and being able to handle them easily.

In order to achieve the above-mentioned object, the underwater object detection / discrimination device according to the present invention is a transmission signal that transmits a transmission clock signal generated in a transmission clock generation circuit into an ultrasonic pulse by gating it with a predetermined width and transmitting it into water. And a wave receiver that receives the ultrasonic reflection echo reflected by the underwater object and converts it into an electric signal, and from the waveform of the electric signal based on the reflection echo received by being connected to the output side of the wave receiver. An envelope detection circuit that obtains envelope information, a zero-cross detection circuit that is connected to the output side of the wave receiver and shapes the electric signal based on the received reflected echo into a rectangular wave, and the transmission clock signal has a predetermined phase. The phase-shifting circuit for shifting the phase, the phase of the phase-shifted transmission clock signal output from the phase-shifting circuit and the waveform shaping electric signal of the rectangular wave output from the zero-cross detection circuit A phase detection circuit having an exclusive OR circuit that outputs a phase comparison output based on the phase of the phase transmission clock signal, and an integration unit that integrates the output of the exclusive OR circuit and outputs the phase information, and the envelope detection circuit. And a display connected to the output side of the phase detection circuit for simultaneously displaying the envelope information and a signal having a predetermined threshold level or more of the phase information, and the presence or absence of an underwater object and its shape. The feature is that it can detect and discriminate.

A preferred embodiment of the underwater object detection / discrimination device according to the present invention will be described below in detail with reference to the accompanying drawings.

First, the relationship between the phase information of the reflection echo from an underwater object such as a school of fish and the envelope information used in the present invention will be briefly described.

For example, an ultrasonic pulse emitted from a fish finder reaches an underwater object such as a fish school and is reflected thereby. Therefore, the instantaneous value P _r of the reflected echo includes the envelope information P and the phase information θ as a signal that changes from moment to moment. The envelope information P and the phase information θ are given by the following equations.

P _r = P sin (ωt + θ) (1) Here, P _ri is the envelope of the reflection echo from the target i existing within the pulse width, φ _i is the initial phase of the transmission wave of the target i with respect to the carrier, and ω is the angular frequency of the transmission wave.

The present invention has been made paying attention to the fact that the instantaneous value P _r of the reflected echo includes the phase information represented by the equation (3).

Therefore, the configuration of the device of the present invention will be described 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 electrode amplifier circuit 12 is connected to the wave transmitter / receiver 14. The output side of the transceiver 14 is connected to the preamplifier circuit 16, and the output side of the preamplifier circuit 16 is connected to a filter circuit, which is substantially a bandpass filter circuit 18.
The output side of the filter circuit 18 is further connected to the amplifier circuit 20, one output terminal of the amplifier circuit 20 is connected to the envelope detection circuit 22, and the other output side of the amplifier circuit 20 is phase. It is connected to the detection circuit 24. The output sides of the envelope contour detection circuit 22 and the phase detection circuit 24 are connected to a display 26, respectively. The other output side of the transmission clock generation circuit 10 is connected to the phase shift circuit 28, and the output side of the 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 that shapes the waveform of an input signal, an exclusive OR circuit 32, and a low-pass filter 34, and the output side of the amplification circuit 20 is connected to the zero-cross detection circuit 30 and branched and enveloped. It is connected to a rectifier circuit 36 that constitutes the detection circuit 22. The output side of the rectifying circuit 36 is further connected to a low pass filter 38, and the output side of the filter 38 is connected to a display 26 for displaying envelope information. 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 which constitutes the phase detection circuit 24.

Next, the operation of the underwater object detection / discrimination device having the above-described configuration will be described.

First, the transmission clock signal generated by the transmission clock generation circuit 10 (see FIG. 2a) is gated to an appropriate width and sent to the power amplification circuit 12 as a transmission pulse for power amplification here. The gated transmit clock signal, or transmit pulse, is as shown in Figure 2a '. The power-amplified transmission pulse is introduced into the transceiver 14. This transducer
At 14, an ultrasonic pulse is generated in synchronization with the transmission clock frequency, which is emitted into the water. If a school of fish or the like exists in the water, the ultrasonic pulse is reflected by the school of fish or the like, and the reflected echo is received by the transducer 14. In this transmitter / receiver 14, the ultrasonic pulse related to the reflection echo is converted into an electric signal to become a reflection echo signal, which is introduced into the preamplification circuit 16. The pre-amplifier circuit 16 pre-amplifies the reflected echo signal to an appropriate level so that the band-pass filter circuit 18 at the next stage performs a suitable filtering operation.
Needless to say, the filter circuit 18 extracts signals in only the necessary band. The reflected signal from the fish school whose band is limited by the filter circuit 18 is amplified by the amplifier circuit 20 to a level necessary for being displayed on the display (see FIG. 2c), and an envelope detection circuit 22 and a phase detection circuit 24 are provided. Will be introduced to. In the phase detection circuit 24, the transmission clock signal generated by the transmission clock generation circuit 10 is phase-shifted by the phase circuit 28 by an appropriate phase φ to obtain a reference clock signal (see FIG. 2B), and the reference clock signal is sent to the exclusive OR circuit 32. . However, the phase of the ultrasonic wave propagating in the water becomes the same every time the propagation distance advances by one wavelength of the ultrasonic wave. Therefore, the phase change can be detected by comparing the phases in any of the phases. The transmission clock signal may be directly used as the reference clock signal without using 28. On the other hand, the signal from the amplifier circuit 20 is wave-shaped by the zero-cross detection circuit 30 from a sine wave to a rectangular wave (see FIG. 2D) and sent to the exclusive OR circuit 32. In this exclusive OR circuit 32,
An exclusive OR between the reference clock signal and the rectangular wave is taken (see FIG. 2e), and the phase difference between them is detected and sent to the low-pass filter 34. The low-pass filter 34 integrates the phase difference signal and converts it into a DC signal (see FIG. 2f) and sends it to the display 26 to display the phase information of the school of fish.

On the other hand, in the envelope detection circuit 22, the signal from the amplification circuit 20 is full-wave rectified by the rectification circuit 36 (see FIG. 2g) and sent to the low-pass filter 38. The low-pass filter 38 smoothes the rectified pulsating flow signal and outputs it as a DC signal (see FIG. 2 h).
(See) Send to the display 26 to display the envelope information of the school of fish.

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

Note that the phase information is different in the phase of the ultrasonic wave of the reflection echo from the fish school obtained for each depth due to the spread in the depth direction of the fish school when there is a reflection object such as a school of fish regardless of the reflection level. Therefore, the change in phase shift can be detected. Therefore,
The phase information becomes a signal larger than the threshold level i (see FIG. 2j) and is clearly displayed as a reflected signal from a school of fish or the like.

FIG. 3 shows an example of the display form of the display 26. display
Envelope information of reflected echoes from underwater objects such as a school of fish is shown in the upper half 26a of 26. In this case, reference numerals 40a and 42a indicate the existence of a school of fish and the like, and reference numeral 44a indicates the shape of the shelf portion on the seabed.

On the other hand, in the lower half 26b of the display 26, reference numerals 40b, 42b indicate phase information of reflected echoes emitted from the school of fish, etc., and reference numeral 44b, in this case, represents the presence of a shelf portion on the seabed. . In particular, in the lower half 26b of this indicator 26, it should be noted the presence of the fish shadow indicated by reference numeral 46. That is, in the upper half 26a, the fish shadows 46, 46 are displayed as if they were part of the shelf portion 44a.
By using the phase information, the fish shadows 46, 46 with roots on the shelf portion 44b can be discriminated together with their shapes.

According to the present invention, as described above, phase information is obtained by using an ultrasonic pulse emitted to an underwater object such as a school of fish so that the existence of the underwater object and its shape can be clearly understood. I am configuring. According to the prior art, since it was determined only by the envelope information, in the case of a small fish school or an underwater object with a small amount of reflection, it was only possible to identify the presence or absence of the underwater object. It is possible to understand the shape of an underwater object and its shape. With this, for example, it is possible to make a decision as to what fishing method the fishing boat adopts or the course of the fishing boat can be selected.

Moreover, according to the present invention, the envelope information and the phase information are simultaneously displayed on the same display. In this case, the size of the object in water is displayed in proportion to the amplitude of the envelope,
On the other hand, the phase information has improved shape display and detection capability. Therefore, there is an advantage that the size and shape of the school of fish or the like can be displayed without both the envelope information and the phase information. Further, displaying the envelope information has an advantage that the fish school can be further identified by know-how of fishermen over many years.

Furthermore, according to the present invention, unlike the prior art that uses only envelope information, it is possible to clearly grasp a fish school with roots, etc., so that it is possible to obtain more accurate information on the underwater matter. There are also advantages.

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

[Brief description of drawings]

FIG. 1 is a block circuit diagram of a device for discriminating and detecting an underwater object such as a school of fish using phase information and envelope information according to the present invention, FIG. 2 is a waveform diagram of each circuit portion of the device, and FIG. It is a schematic explanatory drawing showing the image of envelope information and phase information displayed by the display shown in the figure. 10 …… Transmit clock generation circuit, 12 …… Power amplification circuit 14 …… Transceiver, 16 …… Preamplification circuit 18 …… Band pass filter circuit, 20 …… Amplification 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 …… Rectification circuit 38 …… Low pass filter

 ─────────────────────────────────────────────────── ─── Continuation of front page (56) Reference JP-A-55-107968 (JP, A) JP-A-60-183573 (JP, A) JP-A-54-2156 (JP, A) JP-A-52-1 105852 (JP, A) JP-A-55-89711 (JP, A) JP-A-57-27288 (JP, A) JP-A-59-77373 (JP, A) Actual development Sho-59-149072 (JP, U)

Claims (1)

[Claims] 1. A wave transmitter that gates a transmission clock signal generated by a transmission clock generation circuit with a predetermined width to convert it into an ultrasonic pulse and transmits it in water, and an ultrasonic reflection echo reflected by an underwater object. And a wave receiver for converting into an electric signal, an envelope detection circuit connected to an output side of the wave receiver to obtain envelope information from a waveform of an electric signal based on a reflected echo received, and the wave receiver A zero-cross detection circuit that is connected to the output side of the received electric signal based on the received reflected echo to shape the waveform into a rectangular wave; a phase-shift circuit that shifts the transmission clock signal by a predetermined phase; and an output from the zero-cross detection circuit circuit. Phase comparison output based on the phase of the phase-shifted transmission clock signal by comparing the phase of the rectangular-waveform shaping electric signal with the phase of the phase-shifted transmission clock signal output from the phase-shift circuit. A phase detection circuit having an exclusive OR circuit for transmitting and an integration means for integrating the output of the exclusive OR circuit and outputting it as phase information, and the envelope detection circuit and the envelope connected to the output side of the phase detection circuit. An underwater object characterized by comprising a line information and a display for simultaneously displaying a signal having a predetermined threshold level or more of the phase information and detecting presence / absence of the underwater object and its shape. Detection and discrimination device.