RU2779380C1 - Detector of moving underwater objects against the background of biological noise in a shallow water area inhabited by nipper-prawns - Google Patents

Abstract

FIELD: sensing technology.

SUBSTANCE: invention relates to devices for detecting moving underwater objects. Essence: the device contains a signal processing unit (2), made with the possibility of receiving acoustic signals in the form of natural biological noise from nipper-prawns, an amplitude detector (3), a recording device (4) and a block (5) for displaying information. The signal processing unit (2) includes similar first and second receiving channels (2.1, 2.2), a subtracting device (2.3) and an adaptive filter (2.4). Each of the receiving channels (2.1, 2.2) includes a receiving antenna device (2.1.1, 2.2.1), a bandpass filter (2.1.2, 2.2.2), made with the possibility of registering signals at a frequency of 4200-4600 Hz, and a matching device (2.1.3, 2.2.3).

EFFECT: detection of moving underwater objects in hidden mode.

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Description

The invention relates to hydroacoustic signaling devices, namely to devices for detecting a moving underwater object in shallow water conditions and can be used to protect ships, vessels in harbors and ports, as well as port and other underwater structures.

An alarm device is known (Patent 2124232 of the Russian Federation, IPC 6 G08B 13/24. Alarm device / Trefilov N.A.; Nikolaenko V.A.; Sheremeto Yu.Yu.; Elyagin SV.; Margelov A.A. ; patent holder Ulyanovsk State Technical University of the Russian Federation. - No. 96102923; application 02.15.1996; publ. 12.27.1998. - 1 C: ill.) The device contains a microwave generator, a transmitting antenna, a receiving antenna, an amplitude detector of the received signal, narrowband low-frequency amplifier, switch, analog-to-digital converter, microprocessor module.

The known device generates an alarm signal when an additional object appears in the protected object, and a component with new amplitude and phase appears in the reflected signal, which changes the amplitude-frequency and phase-frequency characteristics of the protected object space area. When comparing the amplitude-frequency or phase-frequency characteristics with the original, the microprocessor module generates an "alarm" signal in accordance with the specified criterion.

The disadvantage of the described analogue is that the operation of the device is assumed in a space limited by statically fixed boundaries.

These shortcomings are eliminated by another known device for detecting a moving marine object, selected as a prototype (Patent 68733 of the Russian Federation, IPC G08B 3/00, G08B 31/00. Device for detecting a moving marine object / Kalashnikov I.I., Kolmogorov B.C., Senchenko A. G., Yurchenko E.N.; Patentee Pacific Naval Institute named after S.O. Makarov - No. 2007126542/22; application 11.07.2007; publ. 27.11.2007, bull. No. 33).

A device for detecting a moving marine object, contains a radiation unit, which includes a high-frequency generator and a radiating antenna device, a signal processing unit, which includes two receiving channels, each of which contains a receiving antenna device and a matching device, as well as a subtractor and adaptive filter. In addition, the device contains an amplitude detector, a recording device and an information display unit.

The disadvantage of the described device is that the signals of technical means of radiation are subject to unmasking the installation site of the emitting device, which will lead to their detection, possible subsequent destruction and search for safe ways for divers to move in shallow water.

The claimed invention is aimed at eliminating this drawback, the technical task of which is: the creation of an acoustic signaling device for detecting a moving underwater object in the Far East region of Russia in shallow waters at depths of up to 8-10 m, inhabited by click beetles that emit characteristic high-frequency signals that create in the area under study, a changing interference pattern.

The implementation of the set technical task allows to achieve the following technical result:

- detection of a moving underwater object in a protected shallow water area due to the use of natural biological noise created by click crabs as acoustic signals that form interference vibrations, which leads to the possibility of fully covering the underwater situation in a covert mode, since the technical means of signal emission are subject to unmasking, which will lead to their detection, possible subsequent destruction and the search for safe routes for the movement of divers in a protected shallow water area.

To achieve this technical result, a “Detector of moving underwater objects against the background of biological noise of a shallow water area inhabited by click beetles” is proposed, containing a signal processing unit configured to receive acoustic signals, which includes similar first and second receiving channels, including two receiving antenna devices, two matching devices, as well as a subtractor and an adaptive filter, while the output of the first matching device is connected in parallel with the first input of the subtractor and the first input of the adaptive filter. The output of the second matching device is connected to the second input of the adaptive filter, the output of which is connected to the second input of the subtractor. The output of the subtractor is connected through an amplitude detector to the input of the recording device, the output of which is connected to the input of the information display unit.

The fundamental difference between the claimed invention and the prototype is that natural biological noise from click crabs is used as acoustic signals, while additionally, the first and second bandpass filters are introduced into the first and second receiving channels of the signal processing unit, respectively, used to register signals in the frequency band 4200-4600 Hz, the inputs of which are connected to the outputs of the respective first and second receiving antenna devices, and the outputs are connected to the inputs of the respective first and second matching devices.

The essence of the claimed invention is illustrated by drawings:

- in Fig. 1 shows a functional diagram of a detector of moving underwater objects against the background of biological noise in a shallow water area inhabited by click beetles;

- in Fig. 2 shows a scheme for conducting experimental studies with an underwater object in a closed bay;

- in Fig. 3 shows the amplitude spectra:

a - passage of an underwater object, b - sea clutter;

- in Fig. 4 shows the amplitude spectra of the passage of an underwater object: c - 10 times noisy by the interference signal, d - without noise;

- in Fig. 5 is a signal processing diagram;

- in Fig. Figure 6 shows the analysis of the level of the signal envelope of the passage of an underwater object: e - the envelope of the passage of an underwater object (signal noisy by 10 times) in the band 4200-4600 Hz (the frequency of click crabs), after processing according to the classical scheme, g - the envelope of the passage of an underwater object ( signal noisy by 10 times) in the band 4200-4600 Hz (frequency of click crabs), after processing using an adaptive filter;

- in Fig. Figure 7 shows the spectrograms of the passage of an underwater object: h - after processing without an adaptive filter, j - after processing with an adaptive filter.

Detector of moving underwater objects against the background of biological noise in shallow waters inhabited by click beetles. Fig. 1 (Function diagram).

In FIG. 1 are presented:

1. Acoustic signals from click crabs

2. Signal processing unit

2.1 First receiving channel

2.1.1 First receiving antenna

2.1.2 First bandpass filter

2.1.3 First matching device

2.2 Second receive channel

2.2.1 Second receiving antenna

2.2.2 Second bandpass filter

2.2.3 Second matching device

2.3 Subtractor

2.4 Adaptive filter

3. Amplitude detector

4. Recorder

5. Information display block

All structural elements in the signal processing unit 2, as well as the amplitude detector 3, the recording device 4 and the information display unit 5 are connected by electrical connections. The acoustic signal from click crabs 1 is connected to the signal processing unit 2 by means of acoustic communication through the aquatic environment. As acoustic signals 1, natural biological noise created by click beetles is used. In the signal processing unit 2, two identical receiving channels 2.1 and 2.2 are formed.

In the signal processing unit 2, the output of each receiving antenna device 2.1.1 and 2.2.1 is connected in series with the input of the respective band-pass filters 2.1.2 and 2.2.2 in order to pass the received acoustic signal of the optimal frequency, the outputs of which are connected to the inputs of the respective matching devices 2.1. 3 and 2.2.3 to form two identical receive channels 2.1 and 2.2. The output of the first matching device of the first receiving channel 2.1 is connected to the first input of the adaptive filter 2.4, the output of the second matching device of the second receiving channel 2.2 is connected to the second input of the adaptive filter 2.4 to generate a normalized signal coming from the output of the adaptive filter 2.4 to the second input of the subtractor 2.3. The output of the subtractor 2.3 through the amplitude detector 3 is connected to the input of the recording device 4. The recording device 4 is used to visually display the processed signal. In addition, the output of the recording device 4 is connected to the input of the information display unit 5 for documenting data.

Results of experimental studies

In FIG. 2 shows the conduct of experimental studies in the water area b. Patrokl (Vladivostok), using equipment for recording and processing the signal "KRAS Kryakva-V" (a complex for recording and analyzing signals), remote receivers "SIG-1" and connecting cables. The remote receiver was located at a distance of 95 meters from the laboratory module. The water area of this bay is a habitat for natural biological noise created by click beetles.

At the beginning of experimental studies, the passage of an underwater object was recorded at a speed of 0.7 knots, as well as sea clutter.

In FIG. Figure 3 shows the creation of approximate real conditions, where an acoustic signal propagates in the marine environment, such as unfavorable hydrological conditions, various degrees of waves, noises of various origins, etc. goals.

Thus, an additive "signal + noise" mixture was formed with an input signal-to-noise ratio (SIR) of up to -18 dB, the amplitude spectra of which are shown in Fig. four.

Further, the received signal implementations were processed using the classical scheme of a typical detection path, as shown in FIG. 5, where a stationary measuring hydrophone (SIG-1), a band-pass filter (PF), an integrator (INT), an adaptive filter (AD) are used as a receiving device, a complex for recording and analyzing signals (KRAS Kryakva-V) is used as a spectrum analyzer ).

The evaluation of the results obtained during the experimental studies was carried out by measuring the “signal + interference” ratio or the excess of the noise emission signal level of an underwater object over the level of the continuous part of the spectrum (CSS) when applying noise emission signal filtering based on the adaptive filtering algorithm and without it.

In FIG. Figures 6 and 7 present the characteristic results of a comparative analysis of the processing of noise emission signals from an underwater object at a speed of 0.7 knots with a classical processing scheme and using an algorithm based on adaptive filtering for an input SNR of -18 dB.

Analysis of FIG. 6 (e) shows that the classical processing scheme allows you to select a low level of amplitude signal disturbances caused by a moving underwater object in an interference field, while the use of an adaptive filter in the circuit allows you to increase the level of amplitude signal disturbances and increase the output SIR of the processing circuit, as shown in the figure. 6(g).

Analysis of FIG. 7 shows that the output SIR when extracting noise emission signals from an underwater object according to the classical scheme was about 3 dB (see Fig. 7 (h)) and 15 dB using adaptive filtering (see Fig. 7 (j)).

The use of the proposed device makes it possible to increase the signal/noise ratio at the output of the processing circuit (Fig. 7).

The device works as follows

As acoustic signals, natural biological noise created by click beetles, located in the aquatic environment of the study area, with a frequency in the range from 3 to 5 kHz is used. As a result of multiple mutual reflection from the rough surface of the sea and the bottom of the wave in the frequency band of the biological noise of the sea, the entire space of the study area is irradiated.

The "reference" amplitude-frequency characteristic (AFC) of the protected water space is received by the first and second receiving channels 2.1 and 2.2 of the signal processing unit 2 through the first and second receiving antenna devices 2.1.1 and 2.2.1 connected in series, the first and second bandpass filters 2.1. 2 and 2.2.2, tuned to the frequency band of biological noise from click crabs and the first and second matching devices 2.1.3 and 2.2.3, which will be necessary to generate a normalized signal in the adaptive filter 2.4. When a moving underwater object appears in the space of the studied area, the first receiving channel 2.1 through the first receiving antenna device 2.1.1 connected in series, the first band-pass filter 2.1.2, and the first matching device 2.1.3, tuned to the optimal receiving frequency, registers the "measuring" The frequency response of the water area, in which the object to be detected can presumably be located. The signal reflected from the object under study is received by the second receiving channel 2.2 as part of the signal processing unit 2. An adaptive filter 2.4 is connected to the second receiving channel 2.2 via electrical connection, which performs the function of generating a “normalized” frequency response of the water space. The resulting "normalized" frequency response is the frequency response of the water area at the time the object was detected. From the output of the adaptive filter 2.4, the normalized signal is fed to the corresponding input of the subtractor 2.3. If the amplitude of the "reference" signal exceeds the generated amplitude threshold of the normalized signal on the screen of the recording device 4, the frequency response of the studied biological, man-made, marine or freshwater object is observed. When an underwater object moves in the water, the threshold value of the device will change accordingly. Thus, the sensitivity of the device will change when the value of the accepted "reference" frequency response changes.

When an additional object of any size appears in the protected area (disappearance or movement of objects at any speed), components with a new amplitude appear in the reflected signal. New amplitude components change the amplitude-frequency characteristics of the space region of the object under study. The difference amplitude signal obtained in the subtractor 2.3 is fed to the input of the amplitude detector 3 to extract the amplitude envelope. After that, the detected signal is fed to the input of the recording device 4 for recording and documenting the data obtained as a result of the study. Visual observation of the received acoustic signal occurs in the information display unit 5, where a decision is made about the presence of a moving foreign object in the area under study.

The claimed invention is of considerable interest to the national economy, as it ensures the protection of biological and man-made marine and freshwater objects. The claimed solution does not adversely affect the ecological state of the environment.

Thus, the claimed invention "Detector of moving underwater objects against the background of biological noise of shallow waters inhabited by click beetles" is a new hydroacoustic security device for protecting ships, vessels in harbors and ports, as well as port and other underwater facilities located in the environment. habitat for click crabs.

The claimed device has the following advantages:

- natural biological noise is used, from click crabs, as acoustic signals that form interference oscillations;

- the ability to detect a moving underwater object against the background of natural biological noise generated by click beetles in shallow waters;

- the ability to effectively use the natural biological noise generated by click beetles to solve technical problems of sonar for the detection of underwater objects.

The claimed device is industrially applicable, since widely used components and products of the radio engineering industry and computer technology are used for its implementation.

Claims (1)

Detector of moving underwater objects against the background of biological noise generated by click crabs living in shallow waters, containing a signal processing unit configured to receive acoustic signals, which includes similar first and second receiving channels, including two receiving antenna devices, two matching devices , as well as a subtractor and an adaptive filter, wherein the output of the first matching device is connected in parallel to the first input of the subtractor and the first input of the adaptive filter, the output of the second matching device is connected to the second input of the adaptive filter, the output of which is connected to the second input of the subtractor, the output of the subtractor device is connected through an amplitude detector to the input of the recording device, the output of which is connected to the input of the information display unit, characterized in that natural biological noise from click crabs is used as acoustic signals, while m additionally, the first and second bandpass filters are introduced into the first and second receiving channels of the signal processing unit, respectively, used to detect signals in the frequency band 4200-4600 Hz, the inputs of which are connected to the outputs of the corresponding first and second receiving antenna devices, and the outputs are connected to the inputs of the corresponding first and second matching devices.

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