JP2825542B2 - Fish finder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial applications]

The present invention relates to a fish finder, and more particularly to a fish finder capable of displaying phase information in a received echo.

[Prior art]

Since the echo level detected by the fish finder differs depending on the reflector, this echo level is important information for identifying the reflector, and conventionally, the shade or the color depends on the level intensity of the obtained echo. You are doing another display.

[Problems to be solved by the invention]

A vibrator for the underwater reflectors 61 and 62 shown in FIG.
Each echo when radiating ultrasonic waves from 63
(A) and (B) of FIG. Echoes from the reflector 61 is observed between the time t ₁ ~t _3, echoes from the reflector 62 is observed between the time t ₂ ~t _4. Therefore, the oscillator 63
The, as shown in the FIG. 7 (C), composite wave of the two echoes to the period of time t ₂ ~t ₃ is reception. Now, when the echo wave f ₁ from the reflector 61 is expressed as f ₁ = A ₁ sinωt, the echo wave f ₂ from the reflector 62 becomes f ₂ = A ₂ sin
(Ωt + θ). θ in this case the phase difference between f ₁ and f ₂
90 ゜. The composite wave ft at this time is ft = A ₁ sinωt + A
₂ sin (ωt + θ). When the amplitudes of the echoes f ₁ and f ₂ are equal (A ₁ = A ₂ ), the change in amplitude with respect to the phase difference θ of the composite wave ft is shown in FIG. From FIG. 8, the phase difference is θ
In the case of x, the amplitude does not change, and conversely, there are places where the point phase does not change depending on the level and θ. However, there is no case where both the amplitude and the phase do not change. When the amplitudes A ₁ and A ₂ are not equal, the relationship in FIG. 8 becomes more complicated,
In any case, it was not possible to completely determine whether there were two reflectors based on only information on the amplitude of the received echo. The present invention has been made in order to eliminate the above-described problems, and provides a fish finder that can detect the number and size of reflectors by detecting also a phase difference of a received echo. The purpose is to do.

[Means for Solving the Problems]

The present invention is a fish finder that displays by color based on the echo intensity of the ultrasonic beam emitted toward the water bottom,
A phase change detecting means for detecting a phase change by comparing the phase of each signal component included in the echo with the phase of the signal component at the initial value is provided, and the phase change amount calculated by the phase change detecting means is provided. Is greater than a predetermined value, the phase change point is displayed in association with the detection timing at this time.

[Action]

According to the above configuration, when there is a delay (advance) of, for example, 30 ° or more at a certain time by the phase change detecting means, a point corresponding to this time is stored in a memory or the like, and then at another time, a point of 30 ° The point at this time is also stored when there is an advance (delay) as described above. If the information on the phase change obtained in this way is superimposed and displayed on the display surface identified and displayed according to the conventional echo intensity,
The density of the fish can be known from the magnitude of the density of the displayed change point, and the fish type can be determined from this density.

【Example】

FIG. 1 is a control block diagram showing one embodiment of the apparatus of the present invention. A transmitter / receiver 1 transmits an ultrasonic beam toward the sea floor and receives an echo of the transmitted ultrasonic beam. Reference numeral 2 denotes a transmission / reception switch. The transmission signal from the transmitter 3 is applied to the transmission / reception device 1 during transmission, and the reception wave from the transmission / reception device 1 is input to the reception amplifier 4 during reception.
Reference numeral 5 denotes a detector for detecting the echo signal from the receiving amplifier 4. Reference numeral 6 denotes an A / D converter for converting a signal from the detector 5 from analog to digital, and reference numeral 7 denotes a memory for storing a signal from the A / D converter 6 at a predetermined address based on an address signal. . Reference numeral 8 denotes a signal processing circuit that converts the data read from the memory 7 into a predetermined video signal so that the display 9 displays the signal according to the intensity of the echo signal. The above is the circuit configuration of the conventional fish finder. A level controller 10 compares a detection signal (shown in FIG. 3A) from the detector 5 with a predetermined reference level Vr. As shown in FIG. 3B, the detection signal is Vr.
Outputs “H” level when the value exceeds. (C) of FIG.
Is an enlarged view of one "H" level period in FIG. 3 (B). Reference numeral 11 denotes a limiter amplifier, which amplifies each amplitude value in the reception signal from the reception amplifier 4 to a constant saturation level as shown in FIG. 12 is
When the level controller 10 is outputting the H level, the rising edge of the signal output from the limiter 11 is detected and the third
This is an edge detection circuit that outputs the trigger pulses e ₀ , e ₁ ... Shown in FIG. Reference numeral 13 denotes a counter, which is an interval T ₀ (=) of each trigger pulse output from the counting edge detection circuit 12.
A counter that counts e ₁ −e ₀ ), T ₁ (= e ₂ −e ₁ )... based on a clock pulse having a period of 1 / n of the period (Ts) of the transmission frequency in FIG. It is. Reference numeral 14 denotes a CPU (Central Processing Unit). The operation of the CPU 14 will be described with reference to the flowchart of FIG. In step S1, i is set to 0, and in step S2
T ₀ is counted. In step S3, the operation of i = i + 1 is performed, and in step S4, | iT ₀ ± ΣTi |> θ / 2π
* T ₀ is determined. That is, it is determined whether or not the phase variation amount θ set for the phase at the start of counting has exceeded. If | iT ₀ ± ΣTi | ≦ θ / 2π * T ₀ , steps S2 to S
When | iT ₀ ± ΣTi |> θ / 2π * T ₀ is reached, the process proceeds to step S5, where “1” is output to the memory 7, and the process returns to step S1. Specifically explaining with reference to FIG. 7 to control the above, the memory 7, the time t ₁ ~t period ₂ "0" is stored, at time t ₂ the phase is changed 90 degrees , the stored "1" for the time t ₂ after the time t ₃ after since 90 ° phase difference at time t ₃ occurs "0" is stored. In this way,
The memory 7 stores data indicating the phase change when the phase of the received echo changes. As a method of displaying the phase change with respect to the received echo, when superimposed and displayed on the display 9 of the fish finder composed of the elements 1 to 8 in FIG. 1, for example, as shown in FIG. A phase change point is displayed with a dot D on the screen where the echo intensity is displayed in each color. If this phase change can be displayed on the display unit 9 alone, as shown in FIG. 5, the position where the data of the phase difference is "1" in the memory 7 is displayed by a vertical line L. Is done. Note that, as in the above embodiment, the phase change of the received echo is
The reason that | T ₀ ± Ti |> θ / 2π * T ₀ was not used to determine whether or not the set fluctuation amount θ was exceeded at each trigger pulse interval is because a filter is incorporated in a normal amplifier. Even if the received echo is inverted by 180 °, the phase change gradually changes at the output of the receiving amplifier and finally changes by 180 ° after a predetermined time.

【The invention's effect】

As described above, the present invention detects a delayed (advanced) phase change in a received echo and superimposes the information on the phase change on a display surface that is color-coded according to, for example, a conventional echo intensity. In this case, the density of the fish can be determined from the density of the displayed change point, and the fish type can be determined from the density.

[Brief description of the drawings]

FIG. 1 is a control block diagram showing an embodiment of a fish finder of the present invention, FIG. 2 is a flowchart showing a control operation of the apparatus of FIG. 1, and (A) to (F) of FIG. FIGS. 4 and 5 are time charts showing the operation of the apparatus of FIG.
FIG. 6 is a diagram showing a display example of a phase change point in the apparatus of FIG. 1, FIG. 6 is a diagram showing the position of a reflector in water when received echoes overlap, and FIGS. 7 (A), (B), and FIG. (C) is a time chart showing the echoes from the respective reflectors shown in FIG. 6 and the combined echoes, and FIG. 8 is a time chart showing the combined echoes of (A) and (B) in FIG. FIG. 4 is a diagram illustrating a relationship between a phase difference and an amplitude value. DESCRIPTION OF SYMBOLS 1 ... Transceiver, 2 ... Transmission / reception switch, 3 ... Transmitter, 4 ... Reception amplifier, 5 ... Detector, 6 ... A / D converter, 7 ... Memory, 8 ... Signal Processing circuit, 9 ... Display, 10 ... Level controller, 11 ... Limiter amplifier, 12 ... Edge detection circuit, 13 ... Counter, 14 ... CPU.

Claims (1)

(57) [Claims] 1. A fish finder for displaying by color based on the echo intensity of an ultrasonic beam radiated toward the water bottom, wherein a phase of each signal component included in the echo is compared with a phase of an initial value of the signal component. By providing a phase change detecting means for detecting a phase change, when the phase change amount calculated by the phase change detecting means exceeds a predetermined value, the moving change point is displayed in association with the detection timing at this time. A fish finder characterized by: