JPS644638B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to seabed depth detection in an underwater detection device.

In recent years, seabed depth information is often required, especially in underwater detection devices that have a function of once recording received signals and displaying them in various display modes.

The present invention is in response to the above-mentioned request, and the depth obtained from the seafloor map is stored in RAM in advance, and the depth data at the corresponding address in the RAM is stored by comparing it with position data from other navigation devices. The purpose is to obtain accurate depth information by reading it out and using it as a guide when detecting depth.

The following description will be made based on the embodiments shown in the drawings.

In the figure, 1 is a navigation device such as NNSS or Loran receiver, and output position data is expressed in latitude and longitude. The position data expressed in latitude and longitude is converted into a corresponding address by an interface 2 (indicated by I/O in the figure) activated for address designation of RAM 3, which will be described later.

The relationship between the above position data and the corresponding address in RAM3 is as follows.

Now, suppose that depth data in a range of 30' in the latitude direction and 30' in the longitude direction is stored at each address in RAM3, for example, 3" x
It is assumed that 3" squares (approximately 90m square) are stored sequentially in correspondence with the latitude and longitude. In this case, the above position data and the address of RAM3 can be considered to be in a paired relationship. Done, Interface 2
can be thought of as having this comparison table. That is, the interface 2 is the navigation device 1.
A search is made to find out which square the positional data corresponds to, and address data corresponding to the corresponding square is output. In this way, the depth data of the position data obtained by the navigation device 1 is stored in the RAM 3.
read out. In the above example, the storage capacity of RAM3 is a total of 360N, assuming N bits in the depth direction (if data is stored every 1m, up to ^2N (m) can be stored).
(K bits).

Assuming that the read depth data is now A(m),
The depth data is led to an addition circuit 4 and a subtraction circuit 5, and is operated on the output value a from the depth width setting circuit 6, and the addition circuit 4 outputs the value A+a and the subtraction circuit 5 outputs the value A-a. . Here, the above value a
First, the depth data A is the average depth within the square, taking into account changes within the same square,
Second, it is set in consideration of variations in the timing of seabed pulse detection on the underwater detector side, and is intended to provide redundancy for the above-mentioned changes and variations. The resulting values A+a, A-
a functions as a prediction gate for seabed detection, as will be described later.

Now, in response to the transmission trigger from the transmission trigger generation circuit 7, the transducer 8 transmits an ultrasonic pulse downward, and the return reflected waves from the target object and the seabed are received and guided to the underwater detection device main body 9. . Reference numeral 10 denotes a depth counting circuit composed of, for example, a counter, which momentarily outputs the propagation distance of the ultrasonic pulse as a numerical value in consideration of the underwater sound speed, and is designed to operate in synchronization with the transmission of waves. The count output value is sent to the latch circuit 14 and also guided to the comparison circuit 11. The comparator circuit 11 outputs the count output value from (A-a) to (A+
gate 1 by sending an output signal only for a certain time in a)
2 is in a conductive state. That is, depth (A-a)
Prediction gates from (A+a) are formed.

13 is designed focusing on the difference in signal level and rising slope between schools of fish and the seabed, and detects signals that are considered to be seabed reflected waves among the input return reflected waves, performs pulse shaping, and outputs them. This is a discrimination circuit. Out of the output pulses from the submarine discrimination circuit 13, those based on interference, high level noise, etc. are generally sent to the gate circuit 1.
2, and the pulse based on the seabed reflected wave passes through the gate 12. Then, the depth count value at the time of generation of the pulse is latched by a pulse based on this seabed reflected wave, and the depth is obtained. The depth is guided to the main body 9 and subjected to necessary processing.

As described above, according to the present invention, since a prediction gate is formed in advance using depth data that is to be used as a guideline, it is possible to prevent the occurrence of erroneous depth. In addition, there is no need for a means to form a prediction gate based on the depth obtained in the past, as in conventional devices.
Furthermore, even if a seafloor pulse is not detected, rapid tracking becomes possible.

Note that although depth information is detected in this embodiment,
If the main body 9 requires a submarine pulse, the latch circuit 14 may be removed and the submarine pulse output from the gate circuit 12 may be directly sent to the main body 9.

[Brief explanation of the drawing]

The figure is a circuit diagram showing one embodiment of the present invention.

Claims (1)

[Scope of Claims] 1. In an underwater detection device that detects underwater conditions by emitting ultrasonic pulses into water and receiving reflected waves caused by the ultrasonic pulse signals, it measures the own ship's position and determines the latitude representing the own ship's position. , a navigation device that outputs a longitude signal; a storage circuit that stores in advance underwater depth data at each position corresponding to the position within a predetermined range on the earth; and a latitude and longitude signal sent by the navigation device. means for specifying a corresponding address in the storage circuit based on the address and reading depth data stored at that address; and a depth counting circuit for successively counting the propagation distance of the emitted sound waves in synchronization with the emission of the ultrasonic pulses. , comprising a gate means controlled based on depth data read from a designated address of the storage circuit and the output of the depth counting circuit, and a signal passing through the gate means among the received reflected waves. An underwater detection device characterized by using waves reflected from the bottom of the water.