JPS5876783A - Circuit for detecting reflected wave from sea bottom - Google Patents

Abstract

PURPOSE:To attain accurate depth information by a circuit wherein a depth obtained from a map of the sea bottom is priorly stored in an RAM, the data at the corresponding address in the RAM is read out in accordance with locational data from the navigation apparatus or so, and thus read out data is used as a guide when checking the actual depth. CONSTITUTION:Depth data at the corresponding address priorly stored in an RAM is read out through an interface 2 in accordance with locational data obtained from a navigation apparatus 1, and then fed to addition and subtraction circuit 4, 5 where the output value from a depth width setting circuit 6 is added to and subtracted from the fed value, respectively. Meanwhile, a transmitting/ receiving unit 8 issues ultrasonic pulses upon transmission trigger form a transmission trigger generating circuit 7, and then the reflected wave from the sea bottom is fed to an underwater sensing device body 9 after receiving by the unit 8. The received waves are counted by a depth counting circuit 10 in synchronism with the transmitted waves, and then applied to a latch circuit 14 and a comparison circuit 11. Only those counted values between the outputs from the addition and subtraction circuits 4, 5 are fed via a gate 12 and a sea bottom decision circuit 13 from the comparison circuit 11 to the body 9 to be processed therein. With this, accurate depth information can be attained.

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 provided in underwater detection devices that have the 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 the RAM in advance, and the depth data at the corresponding address in the RAM is stored by comparing it with the position data from other navigation devices etc. The purpose is to obtain accurate depth information by reading it out and using it as a guide when detecting depth.

The embodiments shown in the drawings will be described below.

In the figure, 1 is a navigation device such as NN5S or Loran receiver, and the output position data is expressed by latitude and longitude. The positional data expressed in latitude and axilla and longitude is converted into a corresponding address by an interface 2 (indicated by Ilo in the figure) which is activated for use in a RAM 3, which will be described later.

The relationship between the above position data and the corresponding address in RAM 3 is as follows.

Now, suppose that depth data in a range of 30' in the latitude direction and 30' in the longitude direction is sequentially stored in each address of RAM3 in a 3 x 3" square (approximately 90 m square) corresponding to the latitude and longitude. In this case, the above position data and the address of RAM 3 can be considered to be in a pairwise relationship, and the interface 2 can be considered to be equipped with this comparison table. 2 searches for which square the position data from the navigation device 1 corresponds to, and outputs the address data corresponding to the corresponding square.In this way, the position data obtained by the navigation device 1 The depth data of is read out from RAM3.

Similarly, in the above example, the storage capacity of the RAM 3 is 36 ON (K bits) in total, assuming N bits in the depth direction (up to 2 N (m) can be stored for data for each poison).

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 counting circuit 6, so that the addition circuit 4 outputs the value Afa, and the energy reduction circuit 5 outputs the value -a. Here, the above value a is calculated based on the following: Firstly, the depth data A is the average depth within the square, and secondly, the depth data A is the average depth within the square, and secondly, the depth data A is the average depth within the square, and secondly, the depth data A is the average depth within the square. It is set in consideration of fluctuations in detection timing, etc., and the entire purpose is to provide redundancy for the above-mentioned changes and fluctuations.

The values A+a and A-a obtained as a result function as prediction gates for detecting the seabed, as will be described later.

Now, with the transmission trigger from the transmission trigger generation circuit 7,
The transducer 8 transmits ultrasonic pulses downward, and the reflected waves from the target object and the seabed are guided to the underwater detection device main body 9 after being received. 10 is a depth counting circuit consisting of, for example, a counter, which outputs the propagation distance of an ultrasonic pulse in several pieces every moment, taking into account the speed of sound in water, and is designed to operate in synchronization with the transmission of waves. There is. The count output value is sent to the launch circuit 14 and also to the comparison circuit 11.
guided by. The comparison circuit 11 has the above-mentioned counting output value (A-α
) to (A+α), the output signal is sent out only for a certain period of time to make the gate 12 conductive. That is, depth (A, -a
) to (A+a) are formed.

13 was designed by focusing on the difference in signal level and rising slope between schools of fish and the seabed, and detects the signal that is considered to be a seabed reflected wave in the input returning reflected liquid, and performs norus shaping. This is a seabed discrimination circuit that outputs. Among the output pulses from the seabed discriminating circuit 13, those based on interference, high-level noise, etc. are generally blocked by the gate circuit 12, and pulses based on seafloor reflected waves pass through the gate 12. Then, the depth count value at the time of generation of the pulse is latched by the pulse based on this seabed reflected wave, and the depth is obtained. The eye 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 based on depth data that should serve as a guideline, it is possible to prevent the occurrence of erroneous depths.

Further, there is no need for a means to form a prediction gate based on the depth obtained in the past as in conventional devices, and furthermore, even if a seafloor pulse is not detected, rapid tracking is possible.

Similarly, in this embodiment, depth information is detected, but if the main body 9 requires a seabed pulse, the latch circuit 14 is removed, and the gate circuit 12 sends the seabed pulse as a blade directly to the main body 9. good.

[Brief explanation of the drawing]

The figure is a circuit diagram showing one embodiment of the present invention. Patent applicant Furuno Electric Co., Ltd.

Claims (1)

[Claims] A device for detecting seafloor reflected waves from a returning V-circle based on the tentative transmission of ultrasonic pulses to rice fields, including a navigation device that outputs positioning data in latitude and longitude; a memory circuit that stores seabed depth data for each fixed area; an interface that converts and specifies the corresponding address of the memory circuit based on the positioning data; and a transmission distance of the transmitted sound wave in synchronization with the transmitted wave. It is equipped with a depth counting circuit that performs sequential counting, and gate means that forms a prediction gate of seabed reflected waves based on the depth data of the address specified by the above interface and the depth counting circuit, and the wave passes through the gate means. A submarine depth detection path characterized in that the signal is a seabed reflected wave.