JPS58198780A - Underwater detecting and display device - Google Patents

Abstract

PURPOSE:To facilitate the discrimination of a fish group at the bottom of the sea, by extracting a reflected signal without detection and making the width of the leading edge part constant by the variation of the waveform rate of a pulse signal after the slice processing which is obtained by generating a slice signal for detection of the sea bottom. CONSTITUTION:Ultrasonic pulses for detection are transmitted to water by a transmitter 1, and reflected waves from various objects are received. The receiving signal is amplified and is detected by a detecting circuit 2 and is delayed in a delay circuit 3 by a time T0 described later. Meanwhile, a signal (a) rectified by a full-wave rectifying circuit 4 has the level compared with a preliminarily set slice level (e) in a wave shaping circuit 5 to transmit a pulse (b). Clock pulses are led from a clock pulse generating circuit 6 to AND circuits 7 and 8. A counter 9 having a count capacity (n) counts inputted clock pulses, and the counted value is reset by the high level part of the pulse (b). A counter 10 counts clock pulses only during the low level of the pulse (b) immediately after the detection of the sea bottom, and the AND circuit 8 is broken when the counted value reaches a value (m).

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for displaying the seabed using a white line display method.

Figure 3 shows the conventional white line display method, and shows the signal (
b) is the base < reflected wave on the seabed after detection within the return reflected wave of the detection ultrasonic pulse that was transmitted toward the ocean. ,
The signal (mouth) is a seabed pulse that has been sliced and further shaped at a level e, which is set by focusing on the difference between the reflection level from a general school of fish and the reflection level from the seabed. signal(
C) shows a signal obtained by gating the above-mentioned seafloor reflected wave @) by the seafloor pulse (B), and this signal (Uga indicator (
recorder) and displayed. Therefore, the leading edge of the seabed is displayed on the display, and then the signal is removed by a predetermined width.

By displaying only the leading edge of the seabed in this way, the seabed can be represented in a linear manner, which has the advantage of making it easier to identify schools of holed fish in particular.

However, although this method is extremely effective when the rising slope of the signal (a) is almost constant, the above rising slope generally changes depending on the soil quality of the seabed, the slope, and the rocking of the ship itself, and the signal The width of the leading edge of the display in (c) will change by several times, and in this case, it will be difficult to distinguish whether the change in width is due to the rising of the seabed or due to bottom-seating fish as described above. Become.

The present invention has been made in view of the above, and the pulse signal after slicing processing, which is obtained by extracting the reflected signal without detecting it and further forming a slice signal for seabed detection, is the wave height of the sliced signal. Focusing on the fact that the waveform rate changes depending on the level, the width of the leading edge portion is made constant regardless of the rising slope of the submarine signal by utilizing the change.

This will be explained below with reference to the drawings.

In FIG. 1, 1 is excited by a control means for transmitting waves (not shown) and transmits a detection ultrasonic pulse 5;
This is a transducer that transmits waves underwater and receives reflected waves from various targets. The received signal is amplified (not shown);
Furthermore, after being detected by the detection circuit 2, the delay circuit 3 is used for a time T, which will be described later. will only be delayed.

On the other hand, the amplified received signal is full-wave rectified by a full-wave rectifier circuit A (see signal a in FIG. 2). The signal a indicates a rising portion of a signal based on waves reflected from the seabed. For example, when the frequency used is 50 KHz, the period of each sine wave is 10 ps. Note that the signal A1 shown by a solid line has a steep rise, the signal A shown by a dotted line has an average rise, and the signal Ag shown by a chain line has a gradual rise.

The full-wave rectified signal a is sent to the next stage shaping circuit 5. The level is compared with the slice level e set in advance, and the pulse b (
Signals b1, b7, b corresponding to signals A1, A9, A8
s) is sent. Incidentally, while the seabed is being detected, the low level width of the pulse b is often longer than one period of the signal a.

Reference numeral 6 denotes a clock pulse generation circuit that sends out pulses of high frequency f, and the clock pulses are guided to AND circuits 7 and 8. Reference numeral 9 denotes a counter having a counting capacity n, which counts the input clock pulses and whose count value is reset at the high level portion of the pulse b. The counter 9 has an output terminal, changes from low level to high level when the count value reaches n, and returns to low level again at the same time as the above-mentioned reset. That is, until the count value reaches n, the low level output is inverted and sent to one input terminal of the AND circuit 7, so that a clock pulse is guided to the counter 9. Conversely, once the count value reaches n, a high level output is sent out,
After the inversion, a low level will be sent to the input terminal, so the clock pulse will be cut off by the AND circuit 7, and therefore the counter 9 will remain in a state where it sends a high level until the reset operation is performed by pulse b. ,last. It is assumed that the sending frequency f of the clock pulse is set so that n clock pulses are generated in one cycle of the signal a. Therefore, as described above, while the seabed is being detected, the count value of the counter 9 is reset by the rise of pulse b, so the count value never reaches n, and as a result, the seabed is not detected. From the moment the first minute of pulse b occurs, counter 9 is forced to have its output in a low level state. In this low level state, the detection of the seabed has ended,
It changes to a high level state after one period of signal a from the rise of the final part of pulse b (not shown), and is maintained until the seabed is detected again in the next wave transmission.

Now, 10 is a counter with a counting capacity m that is enabled to count only when the output level from the counter 9 is low. The counter 10 has an output terminal, and the output changes from a low level to a high level when the count value reaches m. Here, the value m is preset based on the one period width of the signal a, the frequency f, and the slice level e, as will be described later.

As shown in FIG. 1, the counter 10 counts clock pulses only while two other conditions are satisfied in addition to the countable condition. That is, the output terminal of the counter 10 sends out a low level while the count value is between O and m-1, and is sent to the AND circuit 8 after inversion, so the other condition is the low level period of pulse b. .

From the above, the counter 10 counts clock pulses only during the low level period of rehalus b from immediately after the seabed is detected2.
When the count value reaches m, the output is changed to a high level (see d1, d, d!, d4 in Fig. 2) and the AND circuit 8
cut off. After that, the detection of the seabed is completed and the counter 9
At the same time as the output level of counter 1 changes to high level,
The count value of 0 is reset to 0, and then the state becomes uncountable. Note that the countable/uncountable state described above can also be achieved by, for example, providing a gate on the input side of the counter.

Next, the waveform diagram shown in FIG. 2 will be explained based on the above circuit and each function. In addition, the counting capacity of counter 10 is now 3
Set it to 2.

(1) When the full-wave rectified signal a is A1, the rising edge of the ocean floor is steep, so the rising time to the slice level e is short, and therefore the time point at which the pulse b1 is generated is also t.

It will be around the point in time. As mentioned above, the clock pulse train C1 is sent to the counter 10 during the low level period of the shaped pulse b of the signal A. Then, the count value of counter 10 is 3
At the time point 11 when the clock pulse reaches 2, a high level is sent to the output terminal, and the sending of the clock pulse is cut off.

(2) When the full-wave rectified signal a is A. Similarly, the clock pulse train C7 is sent to the counter 1o during the low level period of the shaped pulse b of the signal A.

Then, at time point 12 when the count value of the counter 1o reaches 32, a high level is sent to the output terminal to cut off the sending of clock pulses.

(3) When the full-wave rectified signal a is A3 The clock pulse train C3 is sent to the counter 10 during the low level period of the shaped pulse salt of the signal A8. Then, at time point 18 when the count value of the counter 10 reaches 32, a high level is sent to the output terminal to cut off the sending of clock pulses.

In the above, it can be seen that both times tl and t9.13 exist within one cycle range of the signal a. That is, according to the present invention, in the case of the signal A1 as the leading edge of the seabed in the conventional system, the signal A is used from to to time point 117.

In the case of t. From time 17 to t for signal A8.

While the width changes by two periods due to the rising edge of the signal a as shown in the case from time point 17 to time point 17, it is possible to suppress the width to approximately the same width. Therefore, assuming this width is constant, the average hit is T.・This is the delay circuit 3
If the delay amount is set to , the gate 11 can be controlled by the signal d. In addition, T in the above. Although it can be seen from the above explanation that t can be constant, the starting point t. Since it is unknown, the intermediate value itself cannot be determined. This decision will be made after understanding the start-up conditions of a large number of submarine signals obtained through experiments. This value T0 is set at an intermediate level from the start point to the end of the rise of the submarine signal.
This is ideal for minimizing variations in time points.

Furthermore, if To is made variable within the delay circuit, the front edge of the display can be adjusted.

Although the embodiment shown in FIG. 1 uses a full-wave rectifier circuit as the rectifier circuit, the same effect can be obtained by using a half-wave rectifier circuit as another method.

However, it is necessary to separately determine an appropriate value for the value m of the counter 10 through experiments. This is because, compared to the embodiment shown in FIG. 1, there are no pulses every other pulse among the output pulses b of the shaping circuit 5. In order to further improve the effect in this case, a method may be considered in which the pulse width of the pulse obtained from the shaping circuit 5 is detected and a pulse having the same width as that pulse is generated immediately after the end of the pulse. For example, you can use a reversible counter to count the pulse width in the addition direction, and at the same time as the pulse ends, count it in the subtraction direction, and continue the pulse until the counted value matches the initial value (generally 0). .

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing one embodiment of the present invention.
The figure is a waveform diagram. FIG. 3 is a waveform diagram for explaining the basic white line method. Patent applicant: Furuno Electric Co., Ltd.

Claims (1)

[Claims] An underwater detection and display device that transmits ultrasonic pulses underwater and displays reflected waves, comprising: a rectifier circuit that rectifies the reflected waves; and a rectifier circuit that slices the output of the rectifier circuit at a preset level. death,
A shaping circuit that shapes pulses, a clock pulse generation circuit that sends out a pulse train of a predetermined period, a counter that accumulates and counts the clock pulses only during the inward-level period of the output pulse of the shaping circuit, and a counter that accumulates and counts the clock pulses only when the output pulse of the shaping circuit reaches a predetermined value. an underwater detection display device comprising: an output circuit whose output state is inverted when .