JPS58160879A - Deciding device of bottom material - Google Patents

Abstract

PURPOSE:To facilitate a decision on the bottom material by an underwater object detector, such as a fish finder, by decreasing its gain automatically to some extent where the decision on the bottom material is made, and performing recording up to the sea bottom, i.e. intermediate fish school recording normally and recording from the sea bottom with less density. CONSTITUTION:A transmission part 1 generates transmitted pulses P at a specific period and when a transmitter and receiver 3 is driven through a transmission-reception combining circuit 2, an ultrasonic wave is transmitted periodically and its reflected wave is amplified and sent to a gain switch 5. The output of the gain switch 5 is impressed to a sea bottom detector 7 after amplification 6 to generate a pulse when the reflected signal from the sea bottom arrives, and a time setting circuit 8 is driven by the pulse to generate an output which turns on for an adequately specified time, thereby impressing the output to the gain switch 5. The output of the time setting circuit 8 is impressed to the base of a transistor TR through a resistance R3 and then the TR turns on to connect the input side of the amplifier 6 through a resistance R2. Consequently, an input voltage to a power amplifier 9 drops and a voltage impressed to a recording pen 10 also drops to decrease the density of the recording of the sea bottom; and the light and shade in the record is easily discriminated to decide on the bottom material.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an underwater object detection device such as a fish finder.
Recording-type fish finders, which are related to signal processing equipment used to easily identify the bottom sediments of the seabed, emit ultrasonic waves into the water as a guide, detecting schools of fish and the seabed. When using this fish finder, it is very important to know the bottom quality of the seabed, especially when fishing by trawl or catching fish species near the seabed. be.

Therefore, in the past, the gain of the receiving amplifier was artificially lowered (the sensitivity was lowered to IFi-) to view the seafloor records, and the returning nine seafloor echoes were reflected on the sea surface and then reflected once again on the seafloor. The bottom sediment was judged by looking at the records of the so-called second echo that returned.

In general, the level of reflected waves from the seabed varies depending on the bottom material, with the level decreasing in the order of rock, sand, and mud.

The width of the record, that is, the way the tail is drawn, is usually shorter in the case of rock and longer in the case of sand, and the distribution of record width also varies slightly depending on the type of bottom material. Based on this, el& can be determined based on the records.

Instead of the conventional method of artificially lowering the gain of the receiver amplifier when determining the bottom sediment, the present invention automatically reduces the gain to the extent that the bottom sediment can be identified as soon as a reflected signal from the seabed arrives. The records from the bottom to the bottom, i.e. intermediate records of fish schools, are shown as usual, while the records from the bottom to the bottom are shown in a lighter shade.

A detailed explanation will be given below with reference to examples.

Fig. 1 is a block diagram of the embodiment, and Fig. 2 shows waveforms of each part, and the operation is as follows.

When the transmitter 1 generates a constant periodic transmission pulse P (see Figure 2 ■) and drives the transducer 3 through the transmitter/receiver coupling circuit 2, the ultrasonic waves are transmitted periodically to the school of fish, FlF, and seabed 8.
When the reflected wave from B etc. returns to the US, it passes through the transducer 3 and the transceiver coupling circuit 2, is amplified by the cover amplifier 4 (see Fig. 2), and is then sent to the gain switching unit 5.

The output of the gain switching unit 5 is amplified by the amplifier 46 and then sent to the submarine detector 7.
When the reflected signal from the seabed arrives, it generates a pulse (See Figure 2 θ), and is driven by this pulse to output an output (second (see figure @) is generated by the time setting circuit 8, and this output is applied to the gain switching section 5.

An example of the configuration of the gain control section 5 is as shown in FIG. In the state where the output of the time setting circuit 8 is not applied, that is, before the reflected wave from the seabed arrives, the transistor T
, are off, the output of the preamplifier 4 passes through the resistor R1 to the amplifier 6, is then amplified by the power amplifier 9, and is applied to the recording pen 10.

On the other hand, when the output produced by the time setting circuit 8 is applied to the base of the transistor T1 through the resistor, the transistor Tr is turned on, so the input side of the amplifier 60 is connected to the resistor.
As a result, the input voltage to the power amplifier 90 is low, and therefore the voltage applied to the recording pen 10 is also low, making the seabed record thinner and making it easier to distinguish between shading and other things that occur in the record. This makes it easier to identify rounded sediment.

Here, the duration of the output from the time setting circuit 8 can be set arbitrarily, so it can be determined as appropriate by taking into consideration the recording range of the recording paper, the interval of wave transmission, and the like.

Needless to say, the degree to which the gain is reduced can be arbitrarily selected depending on the situation by making the value of - variable.

As explained above, according to the present invention, the record until the seabed reflection signal is obtained is the same as usual, but the records that start from the seabed and thereafter are automatically thinned, making it easy to identify the bottom material on the seabed. Therefore, it is extremely effective in fishing such as bottom trawl fishing.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the embodiment, FIG. 2 shows operating waveforms of each part, and FIG. 3 shows an example of the gain switching section in FIG. 1. DESCRIPTION OF SYMBOLS 1... Transmission part, 2... Transmission coupling circuit, 3... Transducer/receiver, 4... Front cover amplifier, 5... Gain switching unit, 6...
... Amplifier, 7... Seabed detector, 8... Time setting circuit, 9 - Power amplifier, io-... Recording pen patent applicant Tajo Electric Co., Ltd.

Claims (1)

[Claims] A device for detecting underwater objects using ultrasonic pulses, comprising: a seabed detector that is amplified by an amplification device and generates a pulse by detecting a reflected signal from the seabed; and a seabed detector that is driven by the pulse;
When the outputs of the time setting circuit and the wrinkle time setting circuit provided in the front stage of the amplifier, which generates an output that is continuously turned on for an arbitrarily set period of time, are applied, the gain of the amplifier is controlled. A bottom sediment discriminating device comprising: a gain switching section that operates to decrease the gain.