Method of plotting sea bottom navigation chart

FIELD: hydro-acoustics; navigation of sea-going ships; determination of submersible vehicle position.

SUBSTANCE: proposed method includes running around preset area and radiation of acoustic pulse signal towards sea bottom for each point of navigation chart, forming directional pattern of receiving antenna, reception and conversion of acoustic pulse signals reflected from interface into electrical signals which are amplified and separation of the envelope of these signals; the envelope of electric pulse signals from output of receiving channel is transmitted to analog-to-digital converter which takes accesses of the envelope at digitization frequency equal to double bandwidth of receiving channel from moment of radiation of acoustic pulse signal to moment equal to time required for its passage through preset depth and vice versa; accesses taken in this interval are divided into maximum magnitude of access in this interval; magnitudes are placed according to geographic coordinated and are stored in digital form as digital navigation chart of sea bottom.

EFFECT: enhanced efficiency.

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The invention relates to the field of hydro-acoustics and can be used for navigation of vessels and to determine the location of underwater vehicles.

There is a method of constructing a navigation map of the seabed based on the measurement of depths bathymetric navigation (“Hydroacoustic technology research and development of ocean, Ed. by Its, L.: Gidrometeoizdat, 1984). Here form a narrow beam, radiate toward the bottom of the acoustic pulse signal, record the time of arrival of the reflected from the boundaries of the water-bottom acoustic pulse signal relative to the emitted acoustic pulse signal. On the basis of the received time values calculate the distance to the bottom at this point. The resulting value is correlated with geographic coordinates, which are determined by working with a given accuracy positioning and navigation systems. Sequentially traversing a given area, is its depth map.

There is also known a method of mapping the seabed on the amplitude of the echo from the bottom of the acoustic pulse signal (“Acoustics of the ocean floor”, Ed. by Usepersonal, Pencina, M.: Mir, 1984, p.65-71). Here form a narrow beam in the direction of the seabed emit an acoustic pulse signal, Regis is their amplitude reflected from the boundary between the water-bottom acoustic pulse signal, the measured value of the amplitude is correlated with geographic coordinates, which are determined by working with a given accuracy positioning and navigation systems.

Sequentially traversing a given area, make a map of the amplitude of the reflected pulse signal of the study area of the seabed.

The drawback of both methods is the impossibility of mapping the seabed in areas with smooth topography.

The last method as the most similar to that proposed by the technical nature selected as a prototype.

The task, which directed the claimed technical solution is the compilation of the navigation map of the seabed at the smooth topography of the seabed.

Technical result achieved when solving a task, expressed as the ability to use properties of the acoustic signal to penetrate into the seabed at some depth and be reflected from the boundary of the rocks of the seabed. As an illustration of the layer structure of the seabed unchanged, and the reflected signals unchanged to this area of the seabed.

The problem is solved in that way build the navigation map of the seabed, comprising the sequential traversal of the given area, during which produce radiation in the direction of the seabed structures the practical pulse signal for each point make navigation maps of the seabed, the formation of a narrow beam receiving antenna, receiving and converting the acoustic pulse signals reflected from the boundary layers of the seabed, electric, their amplification and separation of the envelope of these signals, characterized in that the envelope of the electric pulse signals output from the receiving channel serves on the analog-to-digital Converter, which takes a sample envelope with sampling frequency equal to twice the bandwidth of the receive path from the moment of emission of the acoustic pulse signal until a time equal to the time of its passage to a predetermined depth and back, the values of the samples taken in this interval, divided by the maximum value of the sample in this interval, the obtained values set in accordance to the geographical coordinates of this area of the seabed and store in digital form, as digital navigation map of the seabed.

Comparative analysis of the characteristics of the proposed solutions and prototype demonstrates compliance with the proposed solution the criterion of “novelty”.

Distinctive features of the proposed solution perform the following functional tasks.

Signs: “...the envelope of the electric pulse signals output from the receiving channel serves on the analog-to-digital Converter, which takes a sampling round is it with the sampling frequency, equal to twice the bandwidth of the receive path from the moment of emission of the acoustic pulse signal until a time equal to the time of its passage to a predetermined depth and back...allow you to convert the received analog signal into a digital code that gives you the ability to handle it using the computer.

Symptom: “...the values of the samples taken in this interval, divided by the maximum value of the sample in this interval...” - provides independence of sample values from the power of the emitted acoustic signal.

Symptom: “...the resulting values set in accordance to the geographical coordinates of this area of the seabed and store in digital form, as digital navigation map of the seabed...” - converts the received data into a form suitable for further use and reference to geographic coordinates. Thus the set of distinctive features of the proposed solution provides the ability to set up the navigation map of the seabed at the smooth topography of the seabed, using the properties of the acoustic signal to penetrate into the seabed at some depth and be reflected from the boundary of the rocks of the seabed.

The proposed solution to the task is not known from the prior art, i.e. the solution meets criter the Yu of “inventive step”.

The essence of the technical solution is illustrated by drawings.

Figure 1 shows the block diagram of the apparatus for carrying out the mapping.

Figure 2 presents the reflections of the acoustic pulse signal from the boundary layers of the seabed.

3 shows the waveforms of voltages in the circuit of the device.

In the drawings denote: 1 - the transmit path; 2 - radiating antenna; 3 - antenna; 4 - the receive path; 5 - analog-to-digital Converter (ADC); 6 - computer (PC); 7 - navigation system; P_[Izl].- emitted acoustic pulse signal; R_OTR- acoustic signal reflected from the boundary water-soil; P_OTR- acoustic signal reflected from the boundary between 1 and 2 layers of primer; R_OTR- acoustic signal reflected from the boundary between 2 and 3 layers of soil; P_OTR- acoustic signal reflected from the boundary between 3 and 4 layers of soil; U_[Izl].the signal at the output of the transmitting tract; U_Ref.the signal at the input of the receive path; U_PfP.the signal at the output of the receive path; U_p-p- signal reception-transfer.

The method is as follows. The vessel bypass the specified area. During traversal, using the device for mapping (figure 1) for each given point make navigation ka is you, through the transmitting tract 1 form a rectangular pulse U_[Izl].fill sinusoidal signal of the carrier frequency (figure 3). The repetition period, duration, frequency of fill-power rectangular pulse U_[Izl].choose the best for this area mapping. U_[Izl].served on the transmitting antenna 2, which converts the electric signal U_[Izl].acoustic R_[Izl].(figure 2) and emits it toward the bottom. By using the receiving antenna 3 having a narrow focus, take reflected from the boundary layers of the seabed acoustic signals R_OTR, R_OTR, R_OTR, R_OTR(2)transform the acoustic signal into an electric U_Ref.(figure 3). In the receiving channel 4 their increase, there are the envelope of the reception signal U_PfP.(figure 3), which serves to the input of analog-to-digital Converter 5. The latter converts the analog signal output from the receiving channel 4 into a digital code. Analog-to-digital Converter 5 has a sampling frequency f=2·Δf, where Δf is the bandwidth of the receiving channel 4. Code output from the analog-to-digital Converter is fed to the computer 6, which produces software processing of the digitized values. In addition, the transmit section 1 generates a signal U_p-p(figure 3), adopted in which a first logical value 1 at the time of the radiation pulse U _[Izl].and the logical value 0 in the rest of the time. The signal U_p-pserved on the computer 6. The values of the current coordinates of the vessel i, j with navigation system 7, which determines the location of the vessel, also served on the computer 6. Differential signal U_p-pfrom logical 1 to logical 0 take samplessignal U_PfP.where i, j is the current vessel position, k is the sequence number of the sample. Sample remain in the buffer memory of the computer 6, at the same time compare them with a threshold value equal to the value U_PfP.in the absence of a received signal. When exceeding the values U_PfP.threshold conclude that input is reflected from the bottom of the signal and since then counts the time interval T, is equal to the travel time of the emitted signal to a predetermined depth and back: T=2·L/S_SRF.where L is a given depth, With_SRF.- average speed of wave propagation in a stratified medium. At the end of the interval T of the sample no longer stored in the buffer memory until the next difference signal U_p-pfrom logical 1 to logical 0. From the set stored in the buffer memory sample values to determine the largest value. It will correspond to the reflection from the boundaries of the water-soil U_PRM. This value is assigned to the variable In_ij. It is Orok divide by the value In_ijcorresponding to the reflection from the boundary between the water-soil:. The obtained digital valuesput in compliance with the geographical coordinates of this area of the seabed. Sequentially traversing a given area, be it digital map, where each point of the seabed with geographic coordinates i, j, corresponds to the set of numberswhere n=T·f. The obtained values oftogether with their corresponding geographic coordinates remain on any storage medium, the computer 6 (e.g., hard disk). Sequential traversal of the given area is its digital navigation map of the seabed.

This solution allows to obtain navigation map of the seabed with smooth terrain, using the layer structure of the seabed.

The way to build a navigation map of the seabed, including the traversal of a given area, during which produce radiation in the direction of the seabed acoustic pulse signal for each point make navigation maps of the seabed, forming a narrow beam receiving antenna, receiving and converting the acoustic pulse signals reflected from the boundary layer m is rskogo bottom, in electric, their amplification and separation of the envelope of these signals, characterized in that the envelope of the electric pulse signals output from the receiving channel serves on the analog-to-digital Converter, which takes a sample envelope with sampling frequency equal to twice the bandwidth of the receive path from the moment of emission of the acoustic pulse signal until a time equal to the time of its passage to a predetermined depth and back, the values of the samples taken in this interval, divided by the maximum value of the sample in this interval, the obtained values set in accordance to the geographical coordinates of this area of the seabed and store in digital form, digital navigation map of the seabed.