RU2225991C2 - Navigation sonar to illuminate near situation - Google Patents

Abstract

FIELD: underwater acoustics, underwater navigational support of submersible vehicles under complex conditions. SUBSTANCE: invention can be used for detection of objects and their automatic tracking, determination and classification of anchored mines and other objects as well as for conducting hydrotechnical studies of worldwide ocean. Navigation sonar to illuminate near situation has two- dimensional transceiving antenna system, transmission-reception commutator with preliminary processing path, generator and first digital computer system, it is supplemented with second digital computer system, path measuring sound velocity in sea water and digital-analog listening path incorporating amplifier, quadrature demodulator, analog-to-digital converter, data multiplexer and controller. EFFECT: expanded functional potential of sonar. 1 cl, 2 dwg

Description

The invention relates to the field of navigation sonar near-field lighting stations (NGAS OBO) and can be used for navigation support of underwater vehicles in difficult conditions, detection of objects and their automatic tracking, classification of anchor mines and other navigationally-dangerous objects, as well as during World the ocean.

Known active sonar station (HAS) AN / SQS-56, developed by Raytheon Company (USA) [1, 2], which is a typical representative of modern HAS detection and contains a transceiver antenna system, a transmit-receive switch, a probe signal generator with a beamformer in radiation and a power amplifier, independent paths: a path for receiving and detecting an active mode, a path for receiving and detecting a passive mode with its beam shaper, a tracking path, tra CT of listening signals and a digital computer with an operator panel, display and peripheral devices.

The disadvantage of such a station is the presence of only 2 modes: detection and tracking; the error in determining the coordinates associated with the variability of the speed of sound in water; the lack of a classification mode for detected targets, the lack of equipment integration for different modes, as well as the possibility of documenting sonar information in real time.

The closest analogue to the claimed invention in structure, selected for the prototype, is a sonar mine detector (GASM) company Plessey Naval System type PMS-58 [3]. The hydro-acoustic station contains a transceiver antenna system, a receive-transmit switch, a generator device, a preprocessing path, and a digital computer system with an operator panel, a monitor, and peripheral devices. GASM performs the following functions: mine search; classification of anchor mines; classification of bottom mines; Registration of a map of the seabed. Radiation and reception of a hydroacoustic signal is performed by a phased array antenna. The generating device comprises a radiation shaper and is intended for generating a sounding signal. The receive-transmit switch selectively serves one of the three parts of the antenna array and connects it in the radiation mode to the generator device and in the reception mode with preamplifiers. The pre-processing section consists of K modules of the channel processor, each module of which processes signals along 8 channels. Channel processor modules provide reception, consistent filtering, dynamic range compression and digitalization. The digitized data via the optical interface is fed into a digital computer system (DAC). The data processing in the DAC is carried out by the vector processor modules, which are designed to form the DD during reception and primary processing of information and the video generator module, which prepares and processes the data for display on the monitor. The control processor module provides GASM monitoring and control functions from the operator console and is connected via interfaces to the generating device and external consumers.

The disadvantage of such a station is the ability to detect only mines and mine-like objects, the error in determining the coordinates associated with the variability of the speed of sound in water, and the need to install additional GAS if necessary to expand the tasks to be solved.

The objective of the present invention is to expand the functionality of the hydroacoustic station by maintaining in NGAS OBO two DACs and additional paths: a path for measuring the speed of sound, a digital-to-analog listening path and a preprocessing path, made as an integrated controlled path for preprocessing a GAS, which makes NGAS OBO not only the traditional tasks of GASM and GAS detection and tracking, but also provide a more effective solution to the problems of detection of navigation -hazardous objects empower digital processing and display sonar information. In addition, NGAS OBO provides work in the modes of educational and hydrological calculations.

The essence of the claimed invention lies in the fact that in GASM, containing a transceiver two-dimensional antenna system connected via a receive-transmit switch with a preliminary processing path, a generator device, the outputs of which are connected to the inputs of the receive-transmit switch, and the first digital computer system (DAC 1) connected to the outputs of the pretreatment path by two parallel interfaces, a second digital computer system (DAC 2), a path for measuring the speed of sound in fruit drink, are additionally introduced water (AES) and a digital-analogue listening path, moreover, two outputs of DAC 1 are connected to two inputs of DAC 2, the third output of DAC 1 is connected to a digital-analogue listening path, the third input of DAC 2 is connected to a path of AES, DAC 2 is connected to a preprocessing path, output control of DAC 2 is connected to the control input of the generating device, the remaining outputs of DAC 2 are outputs to peripheral devices, and the pre-processing path is made in the form of a multi-channel complex pre-processing path and contains series-connected amplifying unit, a quadrature demodulator, an analog-digital converter, data sealer, and a controller connected to all incoming path in pretreatment units.

Figure 1 shows a generalized structural diagram of the claimed NGAS OBO, where the following notation:

1 - antenna system;

2 - receive-transmit switch;

3 - pretreatment path;

4 - generator device;

5 - CVS 1;

6 - CVS 2;

7 - a path for measuring the speed of sound in sea water;

8 - digital-to-analog listening path;

9 - amplifier device;

10 - quadrature demodulator;

11 - analog-to-digital Converter;

12 - data compactor;

13 - controller.

Figure 2 shows a generalized structural diagram of GASM - a prototype of the invention, where the following notation:

1 - antenna system;

2 - receive-transmit switch;

3 - pretreatment path;

4 - generator device;

5 - CVS 1.

The antenna system 1 is a two-dimensional phased antenna array of K × N acoustic transducers [1, p. 74-82].

The receive-transmit switch 2 can be made according to the diode-transformer circuit together with pre-amplifiers [4, p. 69-73].

The pretreatment path 3 is made in the form of a complex pretreatment path and contains a series-connected amplifier device 9, a quadrature demodulator 10, an analog-to-digital converter 11, a data compactor 12, and a controller 13.

Generator device 4 contains a probe signal generator, a device for generating directivity characteristics and power amplifiers and is traditionally performed [1, pp. 91-99].

DAC 1 is a combination of universal and special processors and has the structure of a multiprocessor computer for digital signal processing.

DAC 2 is a universal computer-controlled control, video processing with the ability to generate information on 2 monitors and communication interfaces with external systems.

The path 7 for measuring the speed of sound in sea water contains an acoustic base, a temperature sensor and a transducer of sound speed to frequency and is made according to the utility model of the Russian Federation according to application No. 20011116355/20 (017269).

The digital-to-analog listening path 8 is a classic DAC and power amplifier circuit.

Declared NGAS OBO works as follows. The radiation of the probing signals and the reception of echo signals is carried out by a two-dimensional antenna system 1 The control device and radiation modes are received from the control unit 2 to the generator device 4 from the DAC 2. The generated probing pulses are fed to a multi-channel power amplifier, where they are amplified and fed through the receive-transmit switch 2 to the antenna system 1, where they are converted into acoustic signals. Acoustic echo signals are received by the antenna system 1, converted into electric ones and fed through the receive-transmit switch 2 to the path 3 for preliminary processing. The equipment of the path 3 is common to all complex modes of the NSAS OBO and is able to change its characteristics when changing the operating modes of the gas-controlled generator under control the operator from the remote control center 2. In path 3 in the amplifying device 9, the signals of each channel are amplified, filtered in the desired band, are compressed dynamic range using VARU, using PP The coordination with the dynamic range of analog-to-digital conversion is provided. In the quadrature demodulator 10, the signal spectrum is transferred with the allocation of the sine-cosine quadrature components, after which the signals are fed to the analog-to-digital converter 11. From the output of the analog-to-digital signal converter, they are transmitted to the data compressor 12, where the data is packaged for transmission via two parallel interfaces in DAC 1. The controller 13 receives commands from DAC 2, controls the operation of path 3 and transmits control and diagnostic information to DAC 2.

In the declared NGAS OBO, the processing of sonar information is divided into the stage of primary processing performed at the stage of one review and the stage of secondary processing performed at several reviews.

At the stage of primary processing the following tasks are solved:

formation of a statistical fan of directivity characteristics in the vertical plane (VP) and horizontal plane (GP);

consistent filtering;

pre-processing with the hospitalization of the signal over a distance;

adaptive formation of detection and tracking thresholds;

semi-automatic (with the participation of the operator) or automatic detection of point and locally extended objects;

measurement of coordinates of detected marks;

formation of forms of detected marks and their issuance for secondary processing;

formation of indicator arrays of hydroacoustic information.

At the stage of secondary signal processing, the following tasks are solved:

semi-automatic or automatic capture of detected targets for tracking and setting trajectories;

automatic tracking of targets, the formation and smoothing of the trajectories of targets, the formation of information about the parameters of the movement of goals;

automatic detection of navigation-hazardous by motion parameters and relative coordinates of targets;

formation of automatic decisions according to the class of the detected target;

formation of formular information on the objectives followed;

reset targets with tracking.

Processing sonar information occurs according to the following algorithm.

At the input of the DAC 1 from the complex path of pre-processing, samples of the complex envelope of signals from K × N sensors are received. In DAC 1 is the formation of L radiation patterns. The directivity characteristics (XI) are formed by the method of weighted summation of the corresponding samples from K sensors located on the same vertical in the antenna.

where x _{n, k} - simultaneous complex samples of the envelope for the nth level sensor K;

_{n, L} is the vertical radiation pattern for the n-th sensor in the L direction;

w _{n, L} is the complex weight coefficient of the tier K in the direction L.

The formation of CN in the horizontal plane is performed in the spectral region for each of the L directions vertically. For one sensing cycle, a predetermined number of directivity characteristics is formed in the field of view (course fan). First, a sample of M points is accumulated for each of the sensors, and the samples overlap. Then the spectrogram is calculated using the fast Fourier transform (FFT) method. The value of the spectral reference is obtained by the formula

where _{L, n} (m) are the complex readings of the diagram in the L-direction along the vertical axis of the sensor n;

Z _{L, n} (m) is the value of the spectral reference at a frequency m of the L-direction;

M is the length of the sample.

Chartforming itself is performed by calculating the weighted sum of samples for the same frequency on N channels. The discrete numbers for calculating the sums depend on the duration of the probe pulse. Formation is carried out according to the following formula:

where G _n (i) is the value of the spectral reference at a frequency k for XN number i;

Z _n (k) is the value of the spectral reference at a frequency k for the sensor n;

W _n (k, i) is the weight coefficient for the sensor n at a frequency k for ХН number i;

N is the number of sensors in the antenna.

Then it returns to the time domain, discarding “extra” points. The return is made by calculating the inverse Fourier transform of the generated horizontal directivity characteristics by the formula

where G _n (k) are the complex horizontal readings from the sensor n;

Z _n (m) is the value of the reference at time m for the sensor n;

M is the length of the sample.

Amplitude correction is performed according to the formed directivity characteristics. Correction is made by multiplying by a constant, which depends on the direction in space, and makes it possible to take into account changes in the concentration coefficient depending on the position of XI.

Next, filtering and calculation of the module, consistent with the emitted signal, is performed. When filtering is performed, a multiplication is performed in each spatial channel of the time sample of complex discrete z _n (m) by the impulse characteristics h (k) for the spatial channels of the main fan CN. The summation of the results of multiplication is carried out on the duration of the signal (T-discrete)

where h (k) are the impulse characteristics of the matched filter;

T is the length of the impulse response.

The obtained values of Y _n (m) are stored for their further use and implementation of the processing algorithm obtained at the stage of diagram-forming sonar image.

The next step is the thinning of the received information. When decimating the signal, the "maximum of N" principle is applied. Thinned signals are sent to prepare for display on monitor 1 in DAC 2 and for further processing.

In CVS 1, two-dimensional median filtering is performed in each of the L directions with a moving aperture, unknown noise parameters are evaluated, the sonar image is stationary, detection thresholds and automatic tracking are generated.

Arrays of data are sent to prepare for display on the monitor screen 2 in DAC 2 and in the automatic detector unit in DAC 1. In the automatic detector unit, calculations are performed according to the specified detection algorithm. Forms are completed for the discovered targets. Prepared forms of detected targets with a number are transmitted for tracking and classification at the operator’s command (in manual mode) or automatically. Detection data is used to determine the coordinates of the targets and the elevation angle of the rays from them. To clarify the coordinates along the heading angle, the total-difference method is used.

In DAC 1, thinning for indication and preparation of indicator arrays is performed and forms are prepared for transmission to the display, registration, documentation and control system (SORDiU). To clarify the speed of the selected object, a single radiation pattern is formed for the inclination angle specified from SORDiU. The speed is adjusted to the maximum value of the cross-correlation function between the spectrum of the formed radiation pattern and the set of filter spectra, each tuned to its own frequency. Also, the spectrum of the generated radiation pattern is transferred down to transfer to the time domain and outputting to the digital-analog listening path 8, intended for generating a listening signal from the digital echo signals of any selected channel.

To ensure the operation of the algorithms, the necessary control parameters are transferred from SORDiU.

In DAC 2 from DAC 1 through two digital interfaces receive sonar data that have undergone primary and secondary processing In DAC 2 is carried out:

management of operating modes of NGAS OBO;

formation of arrays of hydroacoustic information for display, registration and documentation systems;

the formation of forms and tables of classification features;

formation of control signals when setting goals for automatic tracking and solving classification problems;

formation of information arrays and their exchange with external information systems.

Information from the tract 7 to the DAC 2 is supplied for use in hydrological calculations.

Integrated modes of training and hydrological calculations do not have their own separate path and are implemented using the equipment of the integrated preliminary processing path and the corresponding functional software.

The hydro-acoustic navigation station for lighting the near environment has a number of advantages, which with small weight and size characteristics and cost make it possible to detect, classify objects not only in the active mode, but also in the noise-detecting mode (passive mode), and the hydrological calculation mode together with the path for measuring sound speed in the sea water provides for the vertical distribution of the speed of sound the construction of the radiation pattern in order to optimize the position of CN in the airspace and predicting contact zones. The training mode allows you to conduct training exercises on the management of NGAS OBO.

Active detection mode is able to solve the following tasks: ensuring the passage of the vessel through straits and narrownesses; ensuring the definition of the boundaries of minefields consisting of anchor mines; ensuring the determination of passages in minefields; avoidance of mine cans; ascent safety; navigation under ice, detection and classification of anchor mines, single or groups, during operations under water; detection of underwater objects and surface objects, navigation and ice obstacles, wormwood and stains ahead of the ship; display on a color indicator: the coastal edge when passing through the narrowness and approaching the coast; the bottom surface of ice, wormwood and streaks when swimming under the ice; automatic tracking to P targets at the same time.

The passive mode of the hydroacoustic station cannot exist simultaneously with the active mode and is designed to solve the following problems: detection of surface ships and submarines; issuing a true or relative bearing to the target in the information system; providing the necessary data to keep the submarine in the order; automatic tracking of up to 20 detected objects; listening to a signal through a speaker, headphones or remote external audio systems.

Literature

1. Mitko VB, Evtyutov A.P., Gushchin S.E. Hydroacoustic communications and surveillance. L .: Shipbuilding, 1982, p.138-142.

2. The use of digital processing. / Edited by E. Oppenheim. M.: Mir, 1980, p. 429-431.

3. Intemation Defend Revue, 10, 1991, p. 279-284.

4. Kolchedantsev A.S. Hydroacoustic stations. L .: Shipbuilding, 1982.

Claims (2)

1. Navigation hydroacoustic station lighting near the situation (NGAS OBO), containing a two-dimensional transceiver antenna system connected via a receive-transmit switch with a pre-processing path, a generator device, the outputs of which are connected to the inputs of the receive-transmit switch and the first digital computer system (DAC 1 ) connected to the outputs of the preprocessing path by two parallel interfaces, characterized in that an additional second digital computing system is introduced into it EMA (DAC 2), a path for measuring the speed of sound in sea water (AES) and a digital-to-analog listening path, with two outputs of DAC 1 connected to two inputs of DAC 2, a third output of DAC 1 connected to a digital-analog listening path, a third input of DAC 2 connected with the AES path, DAC 2 is connected to the preprocessing path, the control output of DAC 2 is connected to the control input of the generator device, the remaining outputs of DAC 2 are outputs to peripheral devices. 2. NGAS OBO according to claim 1, characterized in that the pretreatment path is made in the form of a multichannel complex pretreatment path and contains a series-connected amplifier device, a quadrature demodulator, an analog-to-digital converter, a data compressor, and a controller connected to all components of the path pre-processing blocks.

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