RU2434246C1 - Method of surveying bottom topography of water bodies and apparatus for realising said method - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: sonar probing of the bottom is additionally carried out using a sonar sensor and/or surveying echosounder placed at different depth horizons from ship-borne hydroacoustic apparatus with possibility of movement thereof in the vertical and horizontal plane via sector scanning with scanning of directional characteristics in radiation mode of a parametric antenna with reception of reflected signals with an antenna of the same dimensions as the excitation antenna of the parametric antenna, wherein the width of the directional characteristic in reception mode is greater than the value of the angle of view, and the scanning plane of the antenna deviates from the vertical location position by an angle of 15 degrees towards the side of movement of the ship. A device for implementing method is also disclosed.

EFFECT: high accuracy of surveying the bottom topography of a water body.

2 cl, 6 dwg

Description

The invention relates to hydrography, in particular to methods and technical means for barometric surveying of the bottom topography by determining depths in a given water area and determining their geodetic coordinates.

A known method of shooting the topography of the bottom of the water with an echo sounder [1], including the passage of a vessel with an echo sounder installed on it with predetermined tacks in the water, emitting hydroacoustic signals to the bottom, receiving signals reflected from the bottom, measuring distances from the receiving-emitting antenna of the echo sounder to the reflecting surface (bottom points) , determination of the ship’s geographic coordinates, determination of the geodetic coordinates of the echo-sounder receiving-emitting antenna, measurement of side, keel and pitching parameters, true heading and speed with bottom, determining the true values of the depths and geodetic coordinates with subsequent recording and display.

It is also known a device for implementing this method, which is an echo sounder [2] containing a transceiving antenna, a transmitting unit, a receiving unit, a control unit, a recording unit, processing for mapping the bottom topography, in which the output of the receiving unit is connected to the input of the receiving unit, output of the transmitting unit connected to the receiving-radiating antenna, the outputs of the receiving-radiating unit are connected to the input of the registration unit, processing and mapping of the bottom topography, the inputs of which are connected to the outputs with oud meters of components of pitching, heading, speed and coordinates, and the control unit is connected to a transmitting unit, a receiving and measuring unit and a unit for collecting information, processing and mapping the bottom topography.

Significant disadvantages of the known method and device are the relatively low accuracy of surveying the topography of the bottom of the water area that does not meet the requirements for hydrographic survey (see, for example: Rules of the hydrographic service, No. 4 (ASG, No. 4. - Survey of the bottom relief, part 2. - Requirements and methods), GUNiO of the Ministry of Defense of the USSR, L., 1984), as well as the significant complexity of the method, due to the need to perform calculations related to determining corrections for the deviation of the actual average speed of sound in water from used in the calculation of the calculated values of the average speed of sound in water for a particular echo sounder, determined indirectly from the measured values of temperature, salinity and density of sea water at standard depth horizons accepted in practice or by directly measuring the speed of sound at evenly distributed points over the entire water area.

Due to the fact that the required reliability of determining the average speed of sound, performed by calculation, is provided only in a small local spatial region in which the temperature, salinity and density of sea water are measured or directly the speed of sound propagation in water for a particular echo sounder, the accuracy of photographing the bottom topography in ultimately burdened by the error due to the influence of small-scale and large-scale variability in time of wind displacement and turbulence of internal waves, underwater currents. This error can reach 3% of the measured depth (see, for example: DE Dinn, BD Loncarevic et al. The effect of so und velocity errors on multibeam sonar depth accuracy // Proccedings of American Hydrograhic Symposium. 1995, p.1001-1009 )

In accordance with the requirements of the standard of the International Hydrographic Organization (see, for example: Notes on hydrography. St. Petersburg, GUNiO of the Ministry of Defense of the Russian Federation, No. 248, 1999, p. 27-32), in areas with depths greater than 200 m, where shooting is carried out in In the interests of the safety of navigation, the mean square error (SEC) of determining the depth should not exceed 0.3%.

When using the known method of shooting a relief and a device for its implementation, the UPC determines the depth for depths up to 100 m from 0.7 to 3.5 m, and for depths up to 200 m from 2.3 to 11.0 m, respectively, which does not satisfy the requirements.

When mapping the bottom topography of the UPC, the bottom topography should not exceed 0.5 mm on the tablet scale, which, in combination with the error in determining the depth by a known method and device for its implementation, in most cases does not make it possible to provide this requirement.

In addition, when surveying the bottom topography with subsequent mapping of the bottom topography, especially in the coastal zone of the sea and in the narrowness, it is necessary to have cartographic information both by land and by the adjacent water area. The use of typographic topographic and navigation maps for these purposes is quite difficult. One of the reasons for this is different cartographic projections. Topographic maps are built in the Gauss-Krueger projection, and navigation maps in the Mercator projection. The same reason is the main obstacle to the use of raster images of printing cards in electronic geographic information systems, which are the means of displaying the mapped information when shooting the bottom topography.

There is also known a method of shooting the bottom topography of the water area and a device for its implementation [3], in which the technical result, which consists in increasing accuracy, is solved due to the fact that the method of shooting the topography of the bottom of the water area with an echo sounder installed on the vessel, including emitting hydroacoustic signals in the direction the bottom, receiving signals reflected from the bottom surface, measuring distances from the receiving-emitting antenna to the bottom, determining the coordinates of the vessel from external sources of information, measuring side, keel and pitching, the true heading and speed of the vessel, referencing the measurement results in time, determining the true depths with the correction for the deviation of the actual speed of sound in water from the calculated one, mapping the information obtained with determining the geodetic coordinates of the measured depths, in which, when determining the true depths, the correction for the deviation of the actual speed sound in water from the calculated one is determined in accordance with the dependence: ΔZ _v = N (C _av / C _o -1), where N is the depth under the keel (N = Σ C _i t _i / 2), C _cp = V _c 4f _and cosαΔf _d - average speed sound propagation in water; С _о is the speed of sound propagation in water for which the echo sounder is designed, f _and is the frequency of the hydroacoustic signal emitted by the hydroacoustic Doppler lag, Δf _d is the Doppler frequency shift between the emitted and reflected hydroacoustic signals of the hydroacoustic lag from the seabed, α is the angle formed by the radiation direction hydroacoustic signal to the bottom surface and the horizon, V _c - vessel speed, determined by geodetic coordinates, C _i - sound velocity in water when measuring depths with an echo sounder, t _i - p The time interval between the emission of the signal and the reception of the echo signal from the bottom, when mapping the topography of the bottom, conjugate topographic and navigation raster maps.

Moreover, in the device for implementing the method, comprising a transmitting antenna, a transmitting unit, a receiving unit, a control unit and a unit for collecting, processing information and mapping the topography of the bottom of the water area, in which the output of the transmitting antenna is connected to the input of the receiving unit, the output of the transmitting unit is connected to the receiving antenna , the outputs of the receiving and measuring unit are connected to the input of the unit for collecting information processing and mapping the relief of the bottom of the water area, the inputs of which are connected to the outputs of the ship and measuring components of pitching, heading, speed and coordinates, and the control unit is connected to a transmitting unit, a receiving-measuring unit and a unit for collecting information, processing and mapping the bottom topography, an additional unit for determining the average speed of sound propagation in water in the direction of emission of a hydroacoustic signal, the input of which through the control unit is connected to the output of the ship’s sonar Doppler speed meter and the output of the receiver of the radio navigation and / or satellite navigation system, and in The output is connected to the input of the unit for collecting, processing information and mapping the relief of the bottom of the water area.

This method, unlike analogues, due to the fact that when determining the true depths, the correction for the deviation of the actual speed of sound in water from the calculated one is determined taking into account the average speed of sound propagation in water through the values of the Doppler frequency shift between the emitted and reflected hydroacoustic signals of the hydroacoustic lag from the seabed , allows to achieve a technical result, which consists in increasing the accuracy of shooting the relief of the bottom of the water area.

However, due to the fact that the survey is carried out by means of measuring equipment installed on a surface vessel subject to the influence of external conditions, the so-called faulty data are present during the survey, which are rejected during the final processing of the measured information. The presence of bad data increases the shooting time, and, accordingly, the complexity of processing.

The amendments introduced in the analogues and prototype depending on the current values of yaw, roll and trim of the measuring equipment carrier also do not fully eliminate the errors in measuring the depths of the water area due to the large inertia of the sensors and to the uneven energy loss not only on the way from vibrator to the bottom and at the bottom (due to incomplete reflection), but also on the way back.

Even more complex conditions arise when the reflected signals are emitted from an obstacle in the aquatic environment. Here we have to reckon with the influence of solid angles inside which the flow of energy of acoustic waves propagates: solid angle, inside which the vibrator sends signals, and solid angle, at which the obstacle area is visible from the center of the wave sensor (see, for example: V. Shuleykin Short course of sea physics. L., Gidrometeoizdat, 1959, p. 400-401).

And if the survey in a known manner provides the necessary requirements for navigation, then when surveying in the interests of searching for objects and pipelines under the bottom silt layer or determining the parameters of the boundaries of the continental shelf, requirements for the accuracy of the survey are not provided.

Hydroacoustic search in such conditions is accompanied by a large number of false alarms.

When shooting in the continental shelf, to fulfill the accuracy requirements, it is necessary to exclude or reduce the influence of errors that are systematic or slowly changing in nature, which include errors caused by the spatio-temporal variability of the sound velocity field in the survey area; errors caused by the deviation of the instantaneous level from the observed at the level post; errors associated with determining the position and orientation of the instrument coordinate system in the ship coordinate system.

When searching for underwater objects and pipelines with a small thickness of silt by a silt pipeline, it is necessary to use only highly directional systems to obtain high resolution. In this case, the system must be low-frequency for good penetration of the signal into the thickness of bottom sediments. The problem of monitoring pipelines and determining the parameters of the boundaries of the continental shelf arises, as a rule, in shallow water, which requires limited dimensions of the antennas. Given the relatively small size of silted objects, it is necessary to use a scan of a narrow parametric beam.

The objective of this technical solution is to increase the accuracy of shooting the bottom topography.

The problem is solved due to the fact that in the method of shooting the bottom topography of the water area, including emitting hydroacoustic signals in the direction of the bottom, receiving signals reflected from the bottom surface, measuring distances from the receiving-emitting antenna to the bottom, determining the coordinates of the vessel from external information sources, measuring the onboard, keel and vertical roll, the true heading and speed of the vessel, the binding of the measurement results in time, the determination of the true values of the depths with the determination of the correction for the deviation of the actual speed orosti sound in water from the calculated, mapping the received information to the definition of geodesic coordinates of the measured depths, wherein determining the true depth correction for the deviation of the actual speed of sound in water, the calculated is determined according to the relationship: ΔZ _v = H _(cf. / C _o - 1), where H is the depth under the keel (H = ΣC _i t _i / 2), C _cp = V _c 4f _and cosαΔf _d is the average speed of sound propagation in water, С _о is the speed of sound propagation in water for which an echo sounder is designed , _{f, and} - the radiation signal frequency hydroacoustic sonar oplerovskim lag, Δf _d - Doppler frequency shift between the emitted and the reflected sonar signals sonar lag from the seabed, α - angle formed by the direction of sonar signal emission to the bottom surface and the horizontal, V _c - ship speed determined by geodetic coordinates, C _i - the speed of sound propagation in water when measuring depths with an echo sounder, t _i is the time interval between the emission of the signal and the reception of the echo signal from the bottom; when mapping the topography of the bottom, topographic and navigational raster charts, unlike the prototype [3], additionally perform sonar bottom sounding with a parametric sonar with a scanning directional characteristic installed at different depth horizons from ship’s sonar aids with the ability to move them both in vertical and horizontal planes using sector-wide scanning method scanning directivity characteristics in the radiation mode of a parametric antenna with the reception of reflected signals by an antenna of the same size, as a pump antenna of a parametric antenna, while the width of the directivity characteristic in the reception mode exceeds the size of the viewing sector, and the plane of scanning of the antenna is deflected relative to the position of the vertical location by an angle of 15 degrees in the direction of movement of the vessel, and to the device for implementing the method containing a receiving-radiating antenna, a transmitting unit , a receiving and measuring unit, a control unit and a unit for collecting, processing information and mapping the topography of the bottom of the water area, in which the output of the transceiver antenna is connected to the input of the receiving-measuring unit, the output of the transmitting unit is connected to the receiving-radiating antenna, the outputs of the receiving-measuring unit are connected to the input of the unit for collecting and processing information and mapping the topography of the bottom of the water area, the inputs of which are connected to the outputs of the ship meters, pitch, heading, speed and coordinates, and the control unit is connected to a transmitting unit, a receiving and measuring unit and a unit for collecting information, processing and mapping the bottom topography, a unit for determining the average speed of sound propagation in water in the radiation of the hydroacoustic signal, the input of which through the control unit is connected to the output of the ship’s hydroacoustic Doppler speed meter and the output of the radio navigation or / and satellite navigation system, and the output is connected to the input of the unit for collecting, processing information and mapping the topography of the bottom of the water area, an additional parametric sonar with a directivity scanning characteristic articulated with a ship by a cable-cable and connected by its inputs and outputs of the control unit and the input the house of the block for collecting, processing information and mapping the relief of the bottom of the water area, a module for visualizing the area of relief, connected by its input to the output of the block for collecting, processing and mapping the relief of the bottom of the water area.

The invention is illustrated by drawings (Fig.1-6).

Figure 1 is a structural block diagram of a device. The device consists of a receiving-radiating antenna 1, a transmitting unit 2, a receiving unit 3, a control unit 4, a unit for determining the average speed of sound propagation in water 5, a unit for collecting, processing information and mapping the topography of the bottom 6, a parametric sonar 7 with a scanning directional characteristic, cable cable 8, module visualization of the relief 9.

The output of the transceiving antenna 1 is connected to the input of the receiving-measuring unit 3, the output of the transmitting unit 2 is connected to the receiving-radiating antenna 1, the outputs of the receiving-measuring unit 3 are connected to the input of the unit for collecting, processing information, and mapping the topography of the bottom of the water area 6, the inputs of which are connected to the outputs of the ship meters of pitching components, heading, speed and coordinates, and the control unit 4 is connected to the transmitting unit 2, the receiving-measuring unit 3 and the unit for collecting information, processing and mapping the topography of the bottom 6, in which A unit for determining the average speed of sound propagation in water 5 in the direction of emission of a hydroacoustic signal has been introduced, the input of which through the control unit 4 is connected to the output of the ship’s hydroacoustic Doppler speed meter and the output of the receiver of the radio navigation and / or satellite navigation system, and the output is connected to the input of the collection unit, information processing and mapping of the relief of the bottom 6 of the water area, parametric sonar 7 with a scanning directional characteristic, articulated with a cable-t vessel osom 8 and connected to its inputs-outputs of the control unit 4 and the input acquisition unit, the information processing and mapping bottom relief waters 6 renderer relief region 9 connected to its input to an output collection unit, the processing and mapping bottom relief waters 9.

The device and principle of operation of blocks 1 ÷ 6 are similar to devices and the principle of operation of blocks 1 ÷ 6 of the prototype [3]. At the same time, as in the prototype, the transceiving antenna 1 is assembled from piezoceramic acoustic transducers located in one housing, which are used both for radiation and reception of signals reflected from the bottom. In the radiation cycle, these transducers are connected in parallel, and during the reception of echo signals they work independently of each other.

The transmitting unit 2 consists of a frequency-stabilized crystal oscillator, a shaper of the period of the emitted pulses, a device for generating the duration of the emitted pulse, a synchronizer, a quantization device, a power amplifier, a converter, a switch.

The generator generates continuous oscillations with a frequency of 4.8 MHz, which by means of a synchronizer is reduced to 600 kHz, and a radiation pulse is formed. The power amplifier amplifies the pulse to the value necessary to excite the electro-acoustic transducers of the transceiving antenna 1. Through the switch, the transducers of the transceiving antenna 1 are connected to the transmitting unit 2 during radiation, and to the receiving-measuring unit 3 during reception.

The receiving unit 3 consists of a block of band amplifiers, an antenna amplifier, a main amplifier, a block of control code drivers, a filter block, an amplitude detector, a low-pass filter, a switch, an output amplifier, and is designed to receive, amplify, and frequency select the received signals.

The control unit 4 consists of a micro-command ROM, an address selection control ROM, a microprogram control LSI, two microprocessors, a ROM, a RAM, a hyphenation scheme, three buffer registers and five lines: address lines, micro-lines, lines D, lines M, lines L, and is designed to generate and broadcast teams and information files received from external sources of information, as well as information located in ROM.

The unit for determining the average speed of sound propagation in water 5 consists of a micro command decoder, buffer stages, an address register, an arithmetic logic device, multiplexers, a decoder, line A, line D, and a battery.

The unit for collecting, processing information and mapping the bottom topography 6 consists of receiving registers, a system trunk unit, an amplifier, a memory manager, an operation unit, a command flow control unit, a microprogram control unit, an interrupt unit, and output registers.

Figure 2 is a block diagram of a parametric sonar 7 with a scanning directional characteristic, including parametric emitting antennas 10 and 11, a receiving antenna 12, a forty-channel pump antenna 13, a shaper 14 of the pump signals with a waveform forming device, a power amplifier 15 for forty-eight channels.

Figure 3 is a structural diagram of a parametric sonar. The structure of the parametric sonar 7 with a scanning directional characteristic includes the shipboard complex SK, cable cable 8 and a towed device (CU). The ship complex includes a signal driver 16-23, a two-channel power amplifier 24 and 25, an echo receiver 26-29, a frequency counter 30, a signal recorder 31, an oscilloscope 32, a bandpass filter 33, a power supply 34. The signal generator consists of two master generators 16 and 18, differential frequency allocation schemes 17, pulse modulators 19 and 21, pulse generator 20, preamplifiers 22 and 23. The echo signal receiver includes a receiver input locking circuit for sending time 29, an amplifier with an adjustable gain Nia 28, a set of lower and upper frequencies of filters 27 and phase locked loop circuit 26.

Cable cable 8 has a double load-carrying braid, three insulated conductive conductors.

The towed device (CU) in addition to the towed body includes the cable-cable matching units with the pump converters 35 and 36 located inside the towed body, the pump converters 37, the receiving antennas 38, the amplitude-limiting circuit of the received signal 39, the pre-amplifier 40, the bandpass filter 41 and matching amplifier 42.

The parametric sonar 7 implements a two-channel scheme for generating a pump signal. The operation of the parametric sonar 7 is that from the master oscillators 16 and 18, the signal is supplied to the pulse modulators 19 and 21, where a signal with the required duty cycle is generated, after which it is amplified by voltage in the preliminary amplifiers 22 and 23. Starting the pulse generator when working with the echo signal recorder is carried out from the signal recorder 31. For operation in the measuring mode, it is provided to start from an internal pulse oscillator with an adjustable frequency of packages. After the preliminary amplifiers, the signal enters the power amplifiers 24 and 25, which are equipped with matching nodes with a cable cable 8. From the outputs of the power amplifiers 24 and 25, passing the cable cable 8, the signal goes to the matching nodes 35 and 36, placed in a towed body, and then fed to one of the pump transducers 37.

At the time of radiation, a control pulse from the pulse generator 20 is supplied to the locking circuit of the input of the receiver 29, which eliminates the possibility of overloading the receiving path at the time of sending. The signal reflected from the underwater object is received by one of the broadband antennas 38, passes through the strong echo restriction circuit 39, is amplified by a pre-amplifier 40. The amplified signal is fed to a band-pass filter 41 with a passband of 2.5-50 kHz, due to which the signals received at the receiving path signals with pump frequencies, low-frequency flow noise from the movement of the towed body, the noise of the carrier vessel. Next, the signal passes to a matching amplifier 42, which performs the task of matching the output impedance of the circuit with the wave impedance of the cable cable 8. Here, the variable signals are separated with the supply voltage of the pre-amplifier, which are transmitted along one conductive core of the cable cable 8. After the cable cable 8, the signal passes to the input of an additional band-pass filter 33, which excludes high-frequency pickups from the outputs of power amplifiers 24 and 25 through a cable cable 8 to the input of the receiver 26-29. Here, the separation of the supply voltage coming from the power supply 34 to the towed device and the echo signals amplified by the pre-amplifier 40 is carried out. After additional filtering, the received echo signals are sent to the receiver, where they are amplified in the adjustable amplifier 28, are filtered in the lower and upper filters frequencies 27, go to the phase-locked loop (PLL), where they are converted into signals with the frequency necessary for the pen recorder 31 to work. For normal operation of the PLL, the signal of the circuits is fed to block 26 isolation of the difference frequency register 17. In addition to the received signals and a visual check is carried out signals.

The towed sonar system includes four pump antennas, three of them are 100 × 200 mm in size, and the fourth is 700 × 28 mm. Moreover, the area of the active radiation surface of all four antennas is 200 cm ² . This allows you to connect any antenna to a power amplifier without additional coordination. Structurally, each antenna is made in the form of 14 mosaic modules, each of which contains 28 elements with resonant frequencies of 150 and 180 kHz.

Broadband highly sensitive cylindrical transducers with tangential polarization and piston resonant antennas were used as receiving antennas.

Parametric sonar antennas 7 emit in the frequency range from 5 to 50 kHz. Average pump frequency 165 kHz. The width of the directivity characteristics at a level of 3 dB is 3 × 6 degrees for antennas radiating in the vertical and horizontal directions, and 1 × 20 degrees for side-view antennas. The sound pressure level, reduced to a distance of 1 m, at a frequency of 20 kHz is 2000 Pa.

The presence of a parametric operating mode allows for relatively small towed body sizes to have almost four highly directional sonars in one device.

The placement of four antennas allows lacquering in horizontal and vertical planes, and also makes it possible to obtain a panoramic image of the bottom topography using an antenna tilted at a 20-degree angle.

Figure 4 is a General view of the module converters multichannel pump antenna. The modules are made in the form of two-sided comb structures 43 with piezoelectric elements 44 made of piezoelectric ceramics of the TsTSNV-1 type with a diameter of 7 mm, a height of 9 mm and a developed overlay 45 made of D16 alloy on a common flange in the nodal plane and connected by a mounting wire 46.

5 is a block diagram of a module for rendering a relief region.

6 - algorithm for processing cartographic information.

The operation of the device is as follows.

According to the command pulses generated by the control unit, in the transmitting unit 2, an acoustic pulse is generated and emitted by the receiving-emitting antenna 1 to the bottom side, as well as receiving and converting acoustic signals reflected by the bottom into an electrical signal, transmitting these signals to the input of the receiving-measuring unit 3, in which electrical signals are generated proportional to the time delays in the arrival of signals reflected from the bottom surface, by which the distances from the receiving-emitting antenna are determined nna 1 to signal reflection points on the seabed.

At the same time, according to command pulses from control unit 4, electrical signals proportional to the Doppler frequency shift of the reference sonar signal from the ship's sonar Doppler speed meter (lag) - the analog of which is the lag described in the book: Absolute and relative lags / Vinogradov K.A., Koshkarev V.I., Osyukhin B.A., Khrebtov A.A. // Shipbuilding, L., 1990, p.30, and electrical signals proportional to the geodetic coordinates x, y from the ship receiver indicator of a satellite or radio navigation system, are fed to the input of the unit for determining the average speed of sound in water 5, in which the average speed of sound in water, C _av is determined in accordance with the dependence: C _cp = V _c 4f _and cosα / Δf _d , where V _c is the speed of the vessel, determined by the geodetic coordinates of the satellite or radio navigation system, f _and is the frequency of the sonar signal g by the hydroacoustic Doppler lag, Δt _d is the Doppler frequency shift between the emitted and reflected hydroacoustic signals of the hydroacoustic Doppler lag from the seabed, α is the angle formed by the direction of the radiation of the hydroacoustic signal to the bottom surface and the horizon. This dependence follows from the fact that for a specific four-beam hydroacoustic Doppler lag type LA-52, which is a standard speed meter on hydrographic vessels, the speed of the vessel is determined in accordance with the dependence: V _c = V _cp / 4f _and cosα · Δf _d .

, где X_i, Y_i - геодезические координаты судна, t_i - время их определения.Simultaneously with determining the speed of the lag, the speed of the vessel is determined by the geodetic coordinates obtained by satellite or radio navigation navigation systems in accordance with the dependence:

where X _i, Y _i - geodetic coordinates of the vessel, t _i - time of their determination.

Further, by command pulses from control unit 4, information from blocks 3, 4, and 5 goes to the unit for collecting, processing information, and mapping the topography of bottom 6, which also receives information from ship meters of pitching and heading components.

In block 6, the correction ΔZ _v to the depths measured by the echo sounder is determined (H = ΣC _i t _i / 2, where C _i is the speed of sound propagation in water, t _i is the time interval between the signal emission by receiving the echo signal from the bottom), for the deviation the actual speed of sound in water from the calculated for a specific echo sounder: ΔZ _v = C _i (C _cp / С _о -1), where С _i is the depth measured by the echo sounder, С _о is the speed of sound propagation in water for which the echo sounder is designed.

Information from the parametric locator 7 is fed to the visualization module of the relief region 9.

Information mapping is carried out by applying the geodetic coordinates of the reflection points of hydroacoustic signals from the seabed onto a tablet, which is built by pairing topographic and navigation raster maps in the following sequence:

- the raster of the navigation map in the Mercator projection is subjected to vectorization of the coastline of the navigation map;

- a site is selected that corresponds to the marine area on which the bottom topography is recorded taking into account the vectorization of the coastline of the navigation map;

- a record is made in the final raster of the navigation map;

- the raster of the topographic map in the Gauss-Kruger projection is reduced to the scale of the navigation map;

- the coordinates of the Gauss-Kruger projection are converted into geographical coordinates;

- the conversion of geographical coordinates to the coordinates of the Mercator projection is performed;

- a raster plot is selected that corresponds to the land (coastal) region;

- the topographic map is written to the final raster;

- based on the results of recordings in the final rasters of the navigation and topographic map, the final raster map of the combined navigation and topographic information in the Mercator projection is built;

- on the final raster map displayed on the display device, the path of the vessel is also displayed.

The principle of operation of the sonar 7 is as follows.

As a survey method, a sector survey was used with scanning directivity characteristics in the radiation mode of a parametric antenna. Reception is carried out by an antenna of the same size as the pump antenna of the parametric antenna. In this case, the width of the directivity characteristic in the reception mode exceeds the size of the viewing sector. To reduce the intensity of bottom reverberation and reduce the influence of multiple echo signals from the surface when working in the shallow sea, the antenna scanning plane is deflected relative to the position of the vertical location by an angle of about 15 degrees in the direction of the ship's movement. The beam scanning sector of the parametric antenna is limited by the angle of incidence, depending on the angle of total internal reflection of the sound beam in the bottom sediments, which varies from 30 to 50 degrees depending on the type and state of bottom sediments. The scanning step, depending on the required angular resolution and maximum search speed, is 3 degrees on each side.

The resolution in the angular coordinate is determined by the width of the directivity and the parametric antenna, which is 3 × 4 degrees at the level of - 3 dB. Range resolution at maximum shooting (search) speed is 0.5-1.5 m for various combinations of viewing parameters.

The survey is carried out on the starboard and left sides by two parametric antennas 61 and 62, the directional characteristics of which, when the elements of the pump antenna 64 are in phase, are tilted 15 degrees forward and the left antenna tilted to the left, and the right antenna to the right one fourth of the size of the scanning sector. The receiving antenna 63 is oriented downward and also tilted forward 15 degrees.

The device uses two scanning modes. During intrapulse scanning, an orthogonal signal is emitted in each direction with its frequency, i.e. a linear frequency-modulated (LFM) signal is emitted simultaneously with a directivity scan over the duration of the probe pulse. In the reception in this case, multi-channel processing is used. In the case of inter-period scanning, either a tonal radio pulse or a chirp signal is emitted in each direction. In the latter case, the processing based on the filter matched with the probe signal is used in the receiving path.

The parametric radiating path of the sonar 7 includes: a shaper 65 of the pump signals with a beamforming device, a power amplifier 66 for forty-eight channels, a pump antenna 63, which is a forty-eight-channel two-resonance antenna.

The pump signal in the form of forty-eight frequency-modulated components with an equidistant per-channel phase shift, which is regulated according to the scanning mode, is supplied to a multi-channel power amplifier 66, then the amplified signal is fed to a two-resonance antenna array that emits a pump signal in predetermined directions. As a result of the nonlinear interaction of acoustic pump waves in the medium, a difference frequency signal with predetermined parameters is generated, and the spatial characteristics of the parametric antenna are determined by the controlled spatial characteristics of the pump wave field.

One parametric antenna provides a scanning sector of ± 15 degrees in the range of difference frequencies from 4 to 20 kHz. Frequency deviation is set by the program. The following scanning modes are provided: manual, continuous intra-pulse, discrete intra-pulse, parcel.

The pump signal generator 65 with a beamforming device comprises a pump signal component synthesizer generating oscillations with frequencies f ₁ = f _m −ðφ (τ) / ðτ and f ₂ = f _in -ðφ (τ) / ðτ.

The law of phase change φ (τ) is formed by a master oscillator of modulating functions. From the synthesizer output, binary signals with frequencies f ₁ and f ₂ are fed to the input of the block of controlled delay lines, the operation mode of which is set by the scan control block. At the outputs of the shaper 65, signals are generated (24 channels with a frequency of f ₁ and 24 channels with a frequency of f ₂ ) with a phase shift successively increasing from channel to channel, determined by the law of envelope variation and adjustable by the pulse duration and repetition period. The pulse duration is adjustable from 0.5 to 32 ms. In manual mode, 32 discrete scanning angles are provided.

Power amplifier 66 consists of two blocks. Each block contains 24 channels. The amplitude of the input signals is 10 V, the output signals are 600 V.

The multi-channel pump antenna 64 is designed to convert the energy of electrical signals into acoustic ones and to form a narrow directivity pattern at the pump frequencies. The antenna consists of two sublattices with resonant frequencies of 65 and 75 kHz. Each sublattice contains 24 modules (Fig. 10). The module has thirty-one transducers that provide a directivity characteristic of 4 degrees wide at a level of - 3 dB. The individual transducers in the module can be frequency tuned to increase the overall antenna efficiency. The modules in the antenna are arranged in alternating order of types with different resonant frequencies. Structurally, the antenna is made in a rectangular welded housing measuring 520 × 330 × 80 mm. After assembly, the radiating surface is filled with a sound-transparent polyurethane compound, which protects the lining from destruction in sea water.

The measurement results of the amplitude-frequency characteristics and directivity characteristics of the parametric radiating path in two planes with beam scanning within the specified angles at a difference frequency of 20 kHz showed the possibility of detecting and monitoring pipelines, closed sludge layers, which is confirmed by an echogram obtained by locating the pipe section at an angle 15 degrees to the vertical with a directivity scan in the perpendicular plane. In this case, the pipe was at the bottom under a thin layer of silt with a thickness of not more than 20 cm. The bottom was a layered structure. An echogram was obtained at a frequency of 12 kHz with a probe pulse duration of 0.5 ms. By scanning the directivity characteristics, echoes from the tube appear in a particular sector of angles.

When visualizing the registered region of the bottom topography, the data for the VRML interpreter (Fig. 5) is generated in the RAM of the computer of the computing device with subsequent loading into the interpreter. For this purpose, a JavaScript node is included in the boot VRML file, whose functions control the area of visible space. Software tools for cartographic visualization are data structures in the SVG format, which supports vector and raster data. The display in the browser of data in the SVG format is carried out by the interpreter of the declarative language SVG. The data in the SVG structure is generated similarly to the formation of data in the VRML format. Based on the data in the XML structure (geospatial information) received from the database upon request, the browser is converted to the SVG structure using XSLT-T. For the simultaneous presentation of geospatial data in a two-dimensional and three-dimensional representation, support is provided for synchronization of navigation across one and the other scene. A rectangle corresponding to the current region of space is displayed on the cartographic scene, the data of which is loaded into the memory of the VRML interpreter. Synchronization from the side of SVG is based on JavaScript functions built into SVG and HTML. Since synchronization on the part of VRML is more difficult, a JavaScript node is included in the VRML boot file with navigation functions that do not allow a three-dimensional image to go beyond the viewport and constantly monitor the coordinates of the viewport. These coordinates serve as necessary information for synchronization with the cartographic scene, which is possible using the HTML timer.

The navigation system is constructed using an alternative principle to the observation point of a three-dimensional scene, which is alternative to the well-known GA technology, in which the standard principle is used - the observation point is located outside the scene and the scene is stationary during navigation, and the coordinates of the observation point and the viewing angle are changed. In this case, the center of rotation is not clearly determined, which is one of the reasons for the loss of image during navigation. In the proposed technology, the observation point is constantly in the center of the observation window and is visualized by a small trihedral of axes, and the beginning of the trihedron is always the center of rotation of the image and when navigating the scene moves relative to this center.

Information from block 6 (Fig. 1) is sent to the relief region visualization module 9 (Fig. 5), by means of which interpolation of height (depth) points is performed by methods of two-dimensional spline functions, and specifically in the form of two-dimensional irregular rational fundamental splines (NURBS) ( Golovanov N.N. Geometric modeling. M., Fizatlit, 2002. - 472 p.), Mathematical expressions of which are not given due to the lack of sufficient space. An advantage of the proposed method is the interpolation of elevation points in the form of two-dimensional rational two-dimensional spline-functions NURBS, which allows you to build a smooth surface for any shape of the relief, even for cliffs with a negative angle of inclination. Secondly, the surface of the relief is determined by the analytical dependence, i.e. a finite set of parameters of a fixed set of functions (polynomial splines). The analytical form of the terrain assignment, i.e. in the form of a superposition of analytic functions of two variables, it allows you to use the entire apparatus of differential geometry to describe the morphometric properties of the relief, for example, calculating the value of a function (height, depth) or its differential (slope) at any point (points) of the domain of the function. Third, NURBS provides the ability to locally edit surface shapes. In addition, for the same area of the earth, the DEM data array using NUBRS will be at least an order of magnitude smaller than with the traditional point representation. Consequently, the use of NURBS improves the efficiency of automated geospatial systems by reducing processing time and the required amount of memory. The use of NURBS in computing is a long-held fact - in the graphics packages of all operating systems, NURBS processing and visualization algorithms are integrated, for example, in low-level graphics packages: DirectX and OpenGL for Windows. However, when constructing a DTM, there are obstacles associated with the effect of the occurrence in some situations of a violation of monotony in surface changes — the local appearance of false oscillations. In the inventive method, this obstacle is removed either by adding new points to the array for interpolation, or by using iso-geometric approximation methods with splines. In the first case, the solution to the problem is associated with an increase in the expert’s work in the iterative procedure for constructing NURBS, and in the second, with a significant complication of the mathematical algorithms of the technology.

The proposed method implements the technology of building a DEM based on NURBS in the form of an iterative expert automated procedure. The programming language used is the MatLab language. In this system, the quality of DEM construction is determined by expert comparison of the position of contours calculated according to NURBS with the position of the corresponding isohypses (isobaths) on the original map.

In a specific implementation of the proposed method, raster maps serve as a source of terrain information.

In the general case, when approximating the profile of the relief with one-dimensional splines, one should specify the values of the first two derivatives at the end points of the section. However, such information is unknown, and it is impossible to obtain it in practice. Therefore, the simplest cubic spline with zero boundary derivatives was used as the base spline for approximating the relief profile along the section. Due to the fact that there are no explicitly defined two-dimensional splines, since it is impossible to construct an infinite system of algebraic equations for matching the first two derivatives in all directions at the adjacent boundaries of two pieces of a spline surface, the construction of a two-dimensional spline function is performed using the tensor product of one-dimensional splines. The coordination of the first two DPC differentials for adjacent rectangular map sections is ensured by overlapping task areas of adjacent NURBS.

Thus, the technology of building DEM in an analytical form based on NURBS allows you to exclude the triangulation stage and thereby eliminate the disadvantages of existing technologies. The proposed implementation of the technology can be adapted to other types of source information, and more complex types of basic splines can be included in it.

When using the proposed method and device for its implementation, intended for shooting the bottom topography of the water area, the requirement for accuracy of determining the depth when shooting the topography of the bottom of the water area is established by the current regulatory documents, due to the possibility of measuring the Doppler frequency shift of the reference sonar signal of the sonar doppler log, absolute speed movement of a vessel with an echo sounder through external sources of information (for example, satellite navigation systems type GPS), which determines the average vertical velocity of sound propagation in aqueous medium.

When shooting the bottom topography with an echo sounder, the mean square error in determining the vertical velocity of sound propagation should not exceed ± 7.5 m / s. The fulfillment of this requirement can be ensured if the speed of the vessel is determined with a mean square error not exceeding ± 0.037 m / s, which can be done provided that geodetic coordinates are determined with a mean square error not exceeding ± 7.8 m.

The navigation systems installed on hydrographic vessels, in particular the combined receiver-indicators of satellite and coast-based satellite navigation and radio navigation systems, make it possible to determine geodetic coordinates with an accuracy of ± 6.0 m, and when operating in differential mode with an accuracy of ± 3.0 m.

When combining topographic and navigation raster maps when mapping the bottom topography, the errors of the resulting raster map are no more than two pixels, for example, for a map scale of 1: 250000 with a resolution of 400 dpi this is 30 m on the ground, which does not exceed the errors of the raster map itself.

In the process of shooting, informative depths are selected from the set of measured depths, which are corrected by corrections for the speed of sound and are tied to the calculated probable coordinates for drawing on a working tablet and for an operational assessment of the quality of shooting.

Performing sonar bottom sounding with a parametric sonar installed at different depth horizons from the ship’s echo sounder with the ability to move both vertically and horizontally using the sector survey method with scanning the directivity in the radiation mode of a parametric antenna with the reception of reflected signals by an antenna of the same dimensions as the antenna pumping a parametric antenna, while the width of the directivity in the receiving mode exceeds the sector value view, and the antenna scanning plane is deflected relative to the position of the vertical location by an angle of 15 degrees in the direction of movement of the vessel, allows you to get a panoramic image of the bottom topography with the pipeline at the bottom.

The use of such a combination, which allows you to combine the capabilities of side view and search under the layer of bottom sediments, in combination with mapping the seabed by measured depths, the points of which are attached to the coordinates, provides control of the bottom and silted pipelines within the shelf zone, in the river basin and inland reservoirs.

The practical implementation of the proposed method and device for its implementation does not present technical complexity in view of the fact that its implementation uses standard measuring instruments installed on hydrographic vessels intended for surveying the bottom topography.

Information sources

1. Kolomiychuk N.D. Hydrography. L., GUNiO of the Ministry of Defense of the USSR, 1988, p. 240-277.

2. Hare R. Depth and position error budgets for multibeam echosounding // International Hydrographic Review. 1995, v. LXXII, No. 2, p. 37-69.

3. Patent RU No. 2340916.

Claims (2)

1. A method for capturing the relief of the bottom of the water area, including emitting hydroacoustic signals in the direction of the bottom, receiving signals reflected from the bottom surface, measuring distances from the receiving-emitting antenna to the bottom, determining the coordinates of the vessel from external sources of information, measuring the side, keel and vertical pitch, true heading and vessel speed, reference of measurement results over time, determination of true depth values with determination of correction for deviation of the actual speed of sound in water from the calculated one, mapping information obtained with the determination of the geodetic coordinates of the measured depths, in which when determining the true depths, the correction for the deviation of the actual speed of sound in water from the calculated one is determined in accordance with the dependence: ΔZ _v = H (C _cp / C _o -1), where N is the depth under keel (H = ΣC _i t _i / 2), C _cp = V _c 4f _and cosαΔf _d is the average speed of sound propagation in water, С _о is the speed of sound propagation in water for which the echo sounder is designed, f _and is the frequency of the sonar signal hydroacoustic Doppler lag, Δf _d - Doppler frequency shift s between the emitted and reflected hydroacoustic signals of the hydroacoustic lag from the seabed, α is the angle formed by the direction of radiation of the hydroacoustic signal to the bottom surface and the horizon, V _c is the speed of the vessel, determined by geodetic coordinates; C _i is the speed of sound propagation in water when measuring depths with an echo sounder, t _i is the time interval between signal emission and reception of an echo signal from the bottom; when mapping the bottom topography, topographic and navigation raster maps are paired, characterized in that they also perform sonar sounding of the bottom with a sonar and / or with an echo sounder installed at different depth horizons from ship’s hydroacoustic equipment with the possibility of moving them both in the vertical and horizontal planes m using a sector-scan method with scanning the directivity characteristics in the radiation mode of a parametric antenna with the reception of reflected antenna signals of the same size as the pump antenna of the parametric antenna, while the width of the directivity characteristics in the receiving mode exceeds the size of the viewing sector, and the antenna scanning plane is deflected relative to the vertical location by 15 ° angle towards the vessel. 2. A device for implementing the method, comprising a transmitting antenna, a transmitting unit, a receiving unit, a control unit and a unit for collecting, processing information and mapping the topography of the bottom of the water area, in which the output of the transmitting and receiving antenna is connected to the input of the receiving and measuring unit, the output of the transmitting unit is connected to the receiving and receiving antenna, the outputs of the receiving and measuring unit are connected to the input of the unit for collecting information processing and mapping the relief of the bottom of the water area, the inputs of which are connected to the outputs of the ship's meters components of pitching, heading, speed and coordinates, and the control unit is connected to a transmitting unit, a receiving and measuring unit, and a unit for collecting information, processing and mapping the bottom topography, and a unit for determining the average speed of sound propagation in water in the direction of radiation of the hydroacoustic signal, the input of which is through the control unit connected to the output of the ship’s sonar Doppler speed meter and the output of the receiver of the radio navigation or / and satellite navigation system, and the output is connected to the input of the unit with ora, processing information and mapping the relief of the bottom of the water area, characterized in that it additionally introduced a sonar with a scanning directional characteristic connected to the ship with a cable cable and connected with its inputs to the outputs of the control unit and the input of the unit for collecting, processing information and mapping the relief of the bottom of the water area module for visualization of the relief area, connected by its input to the output of the block for collecting, processing and mapping the relief of the bottom of the water area.

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