RU2340916C1 - Method of surveying bottom contour of water bodies and device to that end - Google Patents

Abstract

FIELD: physics; measurements.

SUBSTANCE: present invention aims at increasing accuracy of surveying a bottom contour. The method of surveying the bottom contour of a water body using a sonic depth finder, mounted at the bottom of a vessel, involves emitting sonar signals in the direction of the bottom of the water body, reception of signals reflected from the bottom surface, measurement of the distance from the tranceiving antenna to the bottom, determination of the coordinates of the vessel using external information sources, measurement of the board keel and heave, true course and speed of the vessel, matching the measurement results on time, calculation of true values of depth with determination of corrections for deviation of the actual speed of sound in water from the calculated value, and mapping the obtained information with determination of geodesic coordinates of the measured depth. When determining true depth values, correction of deviation of the actual sound speed in water from the calculated value is determined from the expression: ΔZ_v=H(C_av/C_o-1), where H is the under-keel clearance (H=ΣC_it_i/2), C_av=V_s4f_scosαΔf_d is the average speed of sound in water, C_o is the speed of sound in water, at which the sonic depth finder is rated, f_s is the frequency of the sonar signal with hydroacoustic Doppler log, Δf_d is the Doppler frequency shift between the emitted and reflected sonar signals of the hydroacoustic log from the bottom of the water body, α is an angle, formed between the direction of transmission of the sonar signal to the bottom surface and the horizontal, V_s is the speed of sound in water when measuring depth using the sonic depth finder, C_i - speed of sound in water when measured with sonic depth finder, t_i is the time interval between transmission of the signal and receiving the echo signal from the bottom. Topographic and navigation bitmaps are coupled when mapping the bottom contour. The device for implementing the method comprises a transceiving antenna, transmission unit, receiving and measuring unit, control unit and a unit for collecting, processing information and mapping the bottom contour of the water body. The device also has a unit for determining average speed of sound in water, in the direction of transmission of the sonar signal.

EFFECT: increased accuracy of surveying the bottom contour.

2 cl, 7 dwg

Description

The invention relates to hydrography, in particular to methods and technical means for surveying the bottom topography by determining the 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 registration unit, a bottom topography mapping processing, 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, which 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 USSR Ministry of Defense, L., 1984), as well as the significant complexity of the method, due to the need to perform calculations related to the determination of 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 seawater at standard depth horizons accepted in practice or by directly measuring the speed of sound at evenly distributed points throughout the water area.

Due to the fact that the required reliability of determining the average speed of sound by calculation is provided only in a small local spatial area in which the temperature, salinity and density of sea water are measured, or the speed of sound propagation in water for a particular echo sounder, the accuracy of recording the bottom topography is ultimately aggravated error due to the influence of small-scale and large-scale variability in time of wind displacement and turbulence of internal waves, underwater opinions. 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. S.-P., GUNiO of the Ministry of Defense of the Russian Federation, No. 248, 1999, p. 27-33) in water areas with depths over 200 m, at which survey in the interests of safety of navigation, the average square error (UPC) 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.

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 surveying the topography of the bottom of the water area with an echo sounder installed on the vessel, which includes 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 , measurement of side, keel and pitching, the true heading and speed of the vessel, the binding of the measurement results in time, the definition of true depths with the definition of amendments for the deviation of the actual speed of 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 _about -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 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 sonar signal to the bottom surface and the horizontal, V _s - ship speed, determined from the geodetic coordinates, C _i - speed of sound in water at the measured depth sounder, t _i - 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, the topographic and navigation raster maps are paired, and to the device for implementing the method, comprising a receiving-radiating antenna, a transmitting unit, a receiving-measuring unit, a control unit and a data processing, data processing unit 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 output the receiving unit is connected to the input of the unit for collecting information processing and mapping the topography of the bottom of the water area, the inputs of which are connected to the outputs of the ship meters of components of pitching, heading, speed and coordinates, and the control unit is connected to the transmitting unit, the receiving unit and the unit for collecting information, processing and mapping of the relief bottom, in addition, 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 through the control unit with one with a yield of marine sonar Doppler velocimeter and output radionavigation receiver and / or satellite navigation system, and an output connected to the input acquisition unit, the information processing and mapping bottom relief area.

The invention is illustrated by drawings (Fig.1-7). Figure 1. Structural block diagram of the device. The device consists of a receiving-radiating antenna 1, a transmitting unit 2, a receiving-measuring 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.

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 information processing unit and mapping the topography of the bottom 6 of the water area, 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, which will complement 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.

The receiving-emitting 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.

Figure 2. Transmitting unit. The transmitting unit 2 consists of a frequency-stabilized crystal oscillator 7, a shaper 8 of the period of the emitted pulses, a device 9 for generating the duration of the emitted pulse, a synchronizer 10, a quantization device 11, a power amplifier 12, a converter 13, a switch 14.

The generator 7 generates continuous oscillations with a frequency of 4.8 MHz, which through the synchronizer 10 is reduced to 600 kHz, and a radiation pulse is formed. The power amplifier 12 amplifies the pulse to the value necessary to excite the electro-acoustic transducers of the antenna 1. By means of the switch 14, the transducers of the antenna 1 are connected to the transmitting unit 2 during radiation, and to the receiving-measuring unit 3 during reception.

Figure 3. Receiving unit. The receiving unit 3 consists of a block of strip amplifiers 15, an antenna amplifier 16, a main amplifier 17, a block of control code drivers 18, a filter block 19, an amplitude detector 20, a low-pass filter 21, a switch 22, an output amplifier 23 and is intended for receiving, amplifying, and frequency selection of received signals.

Figure 4. Control block. The control unit 4 consists of a micro-command ROM 24, an address selection ROM 25, a microprogram control LSI 26, a micro-command register 27, two microprocessors 28, a ROM 29, a RAM 30, a transfer circuit 31, three buffer registers 32, 33, 34 and five highways : address 35 highway, microcommand 36 highway, D 37 highway, M 38 highway, L 39 highway and is designed to generate and broadcast commands and information files from information received from external sources, as well as information located in ROM.

Figure 5. Block for determining the average speed of sound propagation in water. The unit for determining the average speed of sound propagation in water 5 consists of a microcommand decoder 40, buffer stages 41, address register 42, arithmetic logic unit 43, multiplexers 44, decoder 45, highway A 46, highway D 47, and battery 48.

6. Block for collecting, processing information and mapping the bottom topography. The unit for collecting, processing information and mapping the bottom topography 6 consists of receiving registers 49, a system trunk unit 50, an amplifier 51, a memory manager 52, an operation unit 53, a command flow control unit 54, a microprogram control unit 55, an interrupt unit 56, and output registers 57 .

7. The block diagram of the algorithm for pairing topographic and navigation raster maps.

The operation of the device is as follows. According to the command pulses generated by the control unit 4 in the transmitting unit 2, the acoustic pulse is generated and emitted by the receiving-emitting antenna 1 towards the bottom, as well as receiving and converting the acoustic signals reflected by the bottom into the electrical signal, transmitting these signals to the input of the receiving-measuring unit 3, which produces electrical signals proportional to the time delays of arrival of signals reflected from the bottom surface, by which the distances from the receiving-emitting antenna are determined enny 1 to signal reflection points on the seabed.

At the same time, by command pulses from control unit 4, electric signals proportional to the Doppler frequency shift of the reference sonar signal from the ship's sonar Doppler speed meter (lag), the analogue of which is the lag described in the book: Absolute and relative lags. Vinogradov K.A., Koshkarev V.N., Osyukhin B.A., Khrebtov A.A.// L., Shipbuilding, 1990, p.30, and electrical signals proportional to the geodetic coordinates x, y, from the ship transceiver satellite or radio navigation system is fed to the input of the unit for determining the average speed of sound propagation in water 5, in which the average speed of sound propagation in water C _av is determined in accordance with the dependence:

With _cf = V _s 4f _and cosα / Δf _d , where V _c is the vessel speed determined from the geodetic coordinates of the satellite or radio navigation system, 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 by the signals of the hydroacoustic Doppler log 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 _u cosα · Δf _d . 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:

, где Х_i, Y_i - геодезические координаты судна, t_i - время их определения.

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

Further, by command pulses from control unit 4, information from blocks 3, 4, and 5 enters 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 (Н = 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 an echo signal from the bottom), for deviation the actual speed of sound in water from the calculated for a particular echo sounder: ΔZ _v = С _i (С _compare / 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 mapping is carried out by applying the geodetic coordinates of the reflection points of hydroacoustic signals from the seabed to a tablet, which is built by pairing topographic and navigation raster maps in the following sequence (Fig. 7):

- 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.

When using the proposed method and device for its implementation, designed to capture the bottom topography of the water area, the accuracy requirement for determining the depth when shooting the topography of the bottom of the water area is established by 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 information sources (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 speed of sound propagation should not exceed ± 7.5 m / s. Compliance with this requirement can be ensured if the speed of the vessel is determined with a mean square error not exceeding ± 0.037 m / s, what can be done if geodetic coordinates are determined with a mean square error not exceeding ± 7.8 m. Navigation systems installed on hydrographic vessels, in particular, combined Riemo-indicators of coastal satellite and radio navigation systems allow determining 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 relief, 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 surface of the Earth, which does not exceed the errors of the raster map itself.

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.

Claims (2)

1. The method of shooting the bottom topography of the water area with an echo sounder installed on the vessel, 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 pitching, the true heading and speed of the vessel, the binding of the measurement results over time, the determination of the true depths with the determination of the correction for the deviation of the actual speed of sound in water from the calculated one, mapping the obtained information with determining the geodetic coordinates of the measured depths, characterized in 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 in accordance with the dependence: ΔΖ _v = H (C _cf / C _о -1 ), where H is the depth under the keel (H = ΣC _i t _i / 2), C _av = V _s 4f _and cosαΔf _d is the average speed of sound in water, C _о is the speed of sound in water, for which the echo sounder is designed, f _and - the frequency of the sonar signal hydroacoustic d the Opler 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 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 - speed of sound in water at the measured depth sounder, t _i - the time interval between the emission and the reception signal echo from the bottom, with the bottom topography mapping is performed pairing topographic and avigatsionnyh raster maps. 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 receiving unit is connected to the input of the receiving unit, the output of the transmitting unit is connected to the receiving unit, the output of the receiving and measuring unit is connected to the input of the unit for collecting information processing and mapping the relief of the bottom of the water area, the input of which is connected to the output of the ship’s measuring instruments components, 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, characterized in that an additional unit for determining the average speed of sound propagation in water in the direction of emission of the hydroacoustic signal is introduced, 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 radio navigation and / or satellite navigation system receiver emy, and an output connected to the input acquisition unit, the information processing and mapping bottom relief area.

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