JPH0377091A - Fishfinder - Google Patents

Abstract

PURPOSE:To decide the kind of fish by detecting delay phase variation in a received echo and displaying its phase information to superpose on a display screen where a display classified by colors is made according to the intensity of the received echo. CONSTITUTION:A controller 10 compares the detection signal from a detector 5 with a specific reference level Vr and outputs an 'H' level when the detection signal exceeds the level Vr. A limiter amplifier 11 amplifies each amplitude value of the received signal from a receiving amplifier to a constant saturation level. A counted edge detecting circuit 12 detects the rise of the signal outputted by the controller 10 and outputs a trigger pulse. A counter 13 counts the intervals of respective trigger pulse outputted by the circuit 12 at a period which is 1/n time the period of transmission frequency. A memory 7 is stored with data showing phase variation when the received echo shifts in phase. When the phase shift from the received echo is displayed, the echo intensity is displayed by superposition while classified by, for example, colors on the display part 9 of the fishfinder consisting of a transmitter-receiver 1 - signal processing circuit 8.

Description

[Detailed description of the invention] [Industrial application field]

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

[Conventional technology]

The echo level detected by a fish finder differs depending on the reflector, so this echo level is important information for identifying the reflector. Conventionally, the echo level detected by a fish finder is important information for identifying the reflector. A different display is being performed.

[Problem to be solved by the invention]

FIGS. 7A and 7B show echoes when ultrasonic waves are emitted from the transducer 63 to the underwater reflectors 61 and 62 shown in FIG. 6. The echo from the reflector 61 is observed during the time L lt s, and the echo from the reflector 62 is observed at the time L x ”
Therefore, as shown in FIG. 7(C), the synthesized wave of the two echoes is received by the vibrator 63 during the period of time ~t. Now, the echo wave f1 from the reflector 61 is expressed as r + = A
The echo wave r from the reflector 62 is expressed as r S l n-1. becomes f t = A = sin(ωt+θ). θ
is the phase difference between fl and r, which in this case is 90'. The composite wave rt at this time is rt=A+5tn(1)t+A,
5 inches (ωt+θ). When the echo L, ft(') amplitudes are equal (AI=A t ), FIG. 8 shows the change in amplitude with respect to the phase difference θ of the composite wave rt. As can be seen from FIG. 8, when the phase difference is θX, the amplitude does not change, and conversely, there are places where the bond phase does not change depending on the level, .theta. However, there is no case where both amplitude and phase do not change. When both amplitudes A, , A, are not equal, the relationship in Figure 8 becomes more complicated, but in either case, it is difficult to determine whether there are two reflectors using only the amplitude information of the received echo. It could not be determined completely. This invention was made to eliminate the above-mentioned problems, and provides a fish finder that can also detect the number and size of reflectors by detecting the phase difference of received echoes. The purpose is to

[Means to solve the problem]

The fish finder of the present invention is a fish finder that displays the echo intensity of an ultrasonic beam emitted toward the water bottom in different colors. The phase change point detected by the phase change detection means is also displayed.

[Effect]

According to the above configuration, when there is a delay (advance) of, for example, 30° or more at a certain time, the phase change detection means stores a point for this time in a memory or the like, and then at another time, the point is 30° or more. Even when there is a lead (delay) above, the point at this time is stored. If the information on the phase change obtained in this way is superimposed and displayed on the conventional display screen which is displayed in different colors according to the echo intensity, it will be possible to , the density of the fish is known, and the species of fish can be determined from this density.

【Example】

FIG. 1 is a control block diagram showing an embodiment of the apparatus of the present invention. The I transmits an ultrasonic beam toward the ocean floor, and
This is a transducer that receives echoes of the transmitted ultrasound beam. 2 (It is a transmitter/receiver switch, and when transmitting, transmitter 3
A transmitted signal from the transducer j is applied to the transducer 1, and during reception, a received wave from the transducer j is input to the receiving amplifier 4. 5
is a detector for detecting the echo signal from the reception amplifier 4. 6 is an A/D converter that converts the signal from the detector 5 from analog to digital; 7 is an input/D converter;
This is a memory that stores the signal from the converter 6 at a predetermined address based on the address signal. Reference numeral 8 denotes a signal processing circuit that converts data read from the memory 7 into a predetermined video signal for display on the display 9 according to the intensity of the echo signal. The following is the circuit configuration of a conventional fish finder. Reference numeral 10 denotes a level controller that compares the detected signal from the detector 5 (shown in (A) of FIG. 3) with a predetermined reference level Vr, and as shown in (B) of FIG. It outputs "H" level when the voltage exceeds the current level. FIG. 3(C) is an enlarged view of one "14" level period in FIG. 3(B). A limiter amplifier 11 amplifies each amplitude value of the received signal from the receiving amplifier 4 to a constant saturation level as shown in FIG. 3(D). Reference numeral 12 indicates a trigger pulse e shown in FIG. , el... is an edge detection circuit that outputs . 13 is a counter, and the interval P between each trigger pulse outputted from the count edge detection circuit 12; (-6t e
a), TI(-ex e+)... in (F) in Figure 3
This is a counter that counts based on clock pulses with a period of 1/n of the period (Ts) of the illustrated transmission frequency. 14 is C
This is a PU (central processing unit), and the operation of this CPU 14 will be explained according to the flowchart in FIG. In step S1, I is set to O, and in step S2, TI is counted. In step S3, i=i
An operation of +1 is performed, and in step s4, l iTa
A determination is made that ±ΣTil>θ/2π*T0. That is,
Phase change 1411ff set for the phase at the start of counting
It is determined whether or not iθ has been exceeded. If iTo±ΣTil≦θ/2π*To, go through the loop of steps 82 to S4 and obtain 1iTa±ΣTi〉θ/2
When π*T0 is reached, the process advances to step s5 and the memory 7
0bi is output for , and the process returns to step S. To explain the above control in detail using FIG. 6, "0" is stored in the memory 7 for a period of time t + -j t, and the phase changes by 90 degrees at time t. , time t, and thereafter, "B" is stored, and at time t, 9
Since a phase difference of 0° occurs, "0" is stored at time t and thereafter. In this way, data indicating a phase change is stored in the memory 7 at the time when the phase of the received echo changes. The first method of displaying the phase change of the received echo is
When superimposed on the display 9 of a fish finder consisting of elements 1 to 8 in the figure, for example, as shown in Figure 4, the phase change is displayed on the screen where the echo intensity is displayed in different colors. The point is displayed as a dot D. Also, if this phase change can be displayed independently on the display 9, the fifth
As shown in the figure, the portion where the phase difference data in the memory 7 is "1" is displayed with a vertical line. In addition, as in the above embodiment, it is not determined whether the phase change of the received echo exceeds the set fluctuation amount θ at each interval of each trigger pulse by setting IT, ±Til>θ/2π*T0. Since a normal amplifier has a built-in filter, even if the received echo is reversed by 180°, this phase change will gradually change in the output of the receiving amplifier and eventually become 180°.
'This is because the change occurs after a predetermined period of time.

【Effect of the invention】

As explained above, this invention lags behind the received echo (
Detect the phase change of (advanced) and use the information of this phase change as
For example, if the display is superimposed on a color-coded display screen according to the conventional echo intensity, the density of fish can be determined based on the density of the displayed changing points, and the species of fish can be determined from this density. can be determined.

[Brief explanation of drawings]

FIG. 1 is a control block diagram showing an embodiment of the fish finder of the present invention, FIG. 2 is a flowchart showing the control operation of the device in FIG. 1, and (A) to (F) in FIG. The time chart showing the operation of the device in FIG. 1, FIGS. 4 and 5 are as follows:
FIG. 6 is a diagram showing an example of displaying the phase change point in the device of FIG. 1. FIG. 6 is a diagram showing the position of the underwater reflector when received echoes overlap. (C) is a time chart showing the echoes from each reflector shown in Fig. 6 and the combined echoes, and Fig. 8 is a time chart showing (A) of Fig. 7.
) and (B) are diagrams showing the relationship between the phase difference and the amplitude value in the synthesized echoes. DESCRIPTION OF SYMBOLS 1... Transmitter/receiver, 2... Transmit/receive switch, 3... Transmitter, 4... Receiving amplifier, 5... Wave detector, 6... A
/D converter, 7... memory, 8... signal processing circuit,
9...Display device, 10...Level controller, 11
...Limiter amplifier, 12...Edge detection circuit, 1
3...Counter, 14...CPU.

Claims (1)

[Claims] (1) In a fish finder that displays the echo intensity of an ultrasonic beam emitted toward the water bottom in different colors, a phase change detection means for detecting a phase change in the echo is provided, and the phase change detection means detects a phase change in the echo. A fish finder characterized in that it also displays phase change points.