JPH0321499Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) This invention is an underwater detection display device that displays (over time) the signals obtained by (repeatedly) transmitting and receiving ultrasonic waves underwater. Regarding.

(Prior art and background) Rolling and pitching are considered to be the main causes of position errors of the detected target due to the movement of the ship in underwater detection and display devices. Correction using electronically controlled inclinometers has already been put into practical use.

On the other hand, the amount of variation in vertical errors is generally smaller than that of rolling and pitching, so it has not been considered a big problem.

However, as the performance of equipment has improved, it is now easier to search in waves, on the surface, and in shallow waters, and this influence is no less significant, creating the need for correction.

(Purpose of the invention) This invention was made in view of the above, and is an underwater detection system that detects the wave level, performs depth correction, and then displays a signal and displays the wave condition to improve its recognition. The present invention provides a display device.

(Principle of the invention) If an ultrasonic pulse is transmitted at t=0,
The depth D of the reflecting object that receives waves after t seconds is 2D + d(o) + d(t) = ct...(1) where c is the underwater sound wave, and d(o) and d(t) are the respective values at time 0 and t. Indicates wave level.

From equation (1), D=ct/2-d(o)+d(t)/2...(2) On the other hand, the received signal is sampled every minute time τ and stored in a memory with a capacity M in the depth direction. Then, dl=cτ/2, that is, τ=2dl/c (3) where dl indicates the depth distance corresponding to the first location in the depth direction.

From the above formula, τ is the time required for the sound wave to travel the distance dl corresponding to 1 address, so from this, generally the time t required to write to m addresses (m = 1, 2...M) is mτ, and by substituting the above equation (3) into this, t=2m/cdl...(4) Substituting equation (4) into the above equation (1), D=mdl-d(o)+d(t)/ 2...(5) By the way, the address where the writing of depth D is done is
Then, X=D/dl...(6) Then, by substituting the above equation (5) into equation (6), we obtain X=m-d(o)+d(t)/2dl...(7).

Now, assuming there are no waves, d(o) + d
(t)=0, so X=m, which is no different from normal address specification.

However, when d(o)≠0 at the time of transmission, the write start address Xs is set by substituting m=1, d(t)=d(o), and 8), and when d(o)>0, especially d(o)>dl,
When Xs≦0, signals at and near the sea surface cannot be captured. This is because there is no write address.

Therefore, by adding a value m' of about d(o) _MAX or more obtained from experience to the above equation (8), the above Xs can always be 1 or more.

(Embodiment) FIG. 1 is a circuit diagram of an underwater detection display device that displays a time-lapse display, showing an embodiment of this invention.

In the figure, reference numeral 1 denotes a transducer that transmits and receives ultrasonic pulses based on a transmission trigger from a transmission trigger generation circuit 2. 3 is an amplification/detection circuit for amplifying and detecting the received signal, and 4 is an A/D conversion circuit for converting the amplification/detection signal into a digital signal. 5 is M row N
In a memory having a storage capacity of columns, one transmission signal is written in one column. The memory 5 has a switch 6
N received signals are written over time based on write addresses of X and Y, which will be described later, sent through the .

In addition, in the case of a normal underwater detection display device, a reference clock pulse generation circuit 7 that forms a write address;
Comparison circuit 19, which will be described later, calculates the clock pulses from 1 to
x counter 8 which outputs the next trigger pulse and repeatedly counts until it is reset to 1, Y which subtracts the count from N to 1 each time a trigger pulse is output
A write address is formed by a counter 9 and is led to the memory 5 via a switch 6.

10 is a D-A conversion circuit that converts the signal read from the memory 5 into an analog signal, and 11 is a display that displays the signal. 12 forms row addresses 1 to M and column addresses 1 to N for sequentially reading out signals in the memory 5, and also forms scanning signals for displaying the read signals at appropriate positions on the display screen. This is a readout display circuit. Reference numeral 13 denotes an adder circuit for sequentially reading data from the column address where the latest received signal is written in the direction of older columns. Reference numeral 14 denotes a clock pulse generation circuit which sends out a relatively high frequency pulse which serves as a reference for forming a read address and a scanning signal.

This device is further equipped with an internal accelerometer, an integrating circuit, etc. that detects and outputs the wave level, and uses the average change as a reference to calculate the +- wave level d(t).
A sensor 15 that detects the wave level d(o) at the time of wave transmission using the coincidence pulse described below, a latch circuit 16 that latches the wave level d(o) at the time of wave transmission, and a latch circuit 16 that latches the wave level d(o) at the time of wave transmission by executing the calculation of the above equation (7) as needed. A calculation circuit 17 generates a depth-corrected address based on the calculation result.
An addition circuit 18 that adds m' and a comparison circuit 19 that outputs a coincidence pulse and generates a transmission trigger pulse every time the calculation result matches M are activated.
In FIG. 3 showing the configuration of the sensor 15, an accelerometer 30 measures the acceleration of the vertical rocking of the ship when the ship equipped with the device according to this invention rocks. Integrating circuit 31 integrates the output signal of accelerometer 30 and sends the output to averaging circuit 32 and adding circuit 33. The averaging circuit 32 sends out a signal representing the center level of the wave amplitude.
Adder circuit 33 sends out wave level d(t).

FIG. 2 shows an example of a storage signal or display according to this invention.

In the figure, S is a wave sea surface line (oscillation line), F is a school of fish, etc., and B is a seafloor line. In the sea surface line S, the shaded portion corresponds to the case where the wave is located at the crest of waves at the time of wave transmission.

(Effects of the invention) As explained above, according to this invention, the write address is formed taking into consideration the wave level d(t) component that changes from time to time, so accurate depth correction for waves can be performed. .

Also, set an appropriate value to the address formed in this way.
Since the writing start address is shifted by adding m', the crests of the waves are also sufficiently displayed on the display screen, making it extremely easy and convenient to recognize and understand them.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing one embodiment of this invention. FIG. 2 is a diagram showing an example of a storage signal or display according to this invention. FIG. 3 is a diagram showing the configuration of the sensor 15 shown in FIG. 1.

Claims (1)

[Claim for Utility Model Registration] An underwater detection display device that receives a reflected signal from a reflective object based on transmission, stores it in a memory having a predetermined address capacity, and then reads and displays the signal, transmitting a detection signal. time “o” and time “t”
The respective wave levels d(o) and d
(t), a latch circuit that latches the wave level d(o), and a counted value m that performs counting in synchronization with the transmission of the detection signal.
From the output of the sensor, latch circuit, and counter, calculate and an addition circuit that adds a value m' corresponding to the wave amplitude to the calculation result X, and the value of the addition result is used as the write address of the memory. Underwater detection display device.