RU2582897C2 - Radiating channel of parametric sonar - Google Patents

Abstract

FIELD: physics, acoustics.

SUBSTANCE: invention relates to acoustic location systems which employ parametric radiating systems which generate narrow-directed beams of low-frequency acoustic signals. The primary field of use is hydroacoustics, as well as ultrasonic flaw detection, medicine, fish detection and geolocation. The radiating channel of the parametric sonar comprises two or more high-frequency signal generators, the output of each of which is connected to the signal input of the corresponding pulse modulator, the control inputs of all pulse modulators are connected to the output of a pulse generator, and the outputs of the pulse modulators are connected through power amplifiers to acoustic antenna elements, acoustic antenna elements of each frequency are located at a separate input of an acoustic waveguide, the inputs of the waveguide are not acoustically connected to each other and are acoustically connected to the output of the waveguide, which is acoustically connected to the location medium.

EFFECT: high efficiency of operation.

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Description

The invention relates to acoustic location systems using parametric radiating systems that form narrowly focused beams of low-frequency acoustic signals. The predominant area of use is sonar, as well as ultrasonic flaw detection, medicine, fishing, geolocation.

Currently, the so-called parametric emitters are widely used to form narrowly directed beams of low-frequency acoustic signals, using the effect of the interaction of two or more high-frequency acoustic signals in media that have non-linearity of their elastic parameters [1-3]. In this case, the formation of a low-frequency acoustic signal occurs in the medium itself along the entire propagation path of the initial high-frequency acoustic signals. It should be noted that almost all real media are characterized by non-linearity of elastic characteristics and parametric radiators can be implemented in them. Parametric emitters are components of various sonar location systems, medical devices, ultrasonic flaw detectors and other acoustic systems. The most widely used parametric systems are found in sonar.

Known parametric sonar PGL-300 [2, p. 208-209], using a parametric radiating path, containing two high-frequency signal generators, the outputs of which are connected to two inputs of the adder, the output of the adder is connected to the signal input of a normally closed pulse modulator, the control input of which is connected to the output of the pulse generator. The output of the pulse modulator through a power amplifier is connected to an acoustic antenna that is in acoustic contact with the location medium. An acoustic antenna may consist of one single-frequency piezoelectric plate or of several piezoelectric elements operating at a resonant frequency. The first high-frequency generator generates a sinusoidal signal with a frequency f ₁ , the second high-frequency generator generates a signal with a frequency f ₂ . In the adder, these signals are summed, and their sum is fed to the signal input of a pulsed normally closed modulator. The pulse generator generates periodically repeating video pulses arriving at the control input of the modulator and allowing the sum of high-frequency signals to pass through them, which are then fed to the input of the power amplifier, and from its output to an acoustic antenna emitting acoustic signals with frequencies f ₁ and f ₂ . In the location environment, these signals interact and form a low-frequency signal with a frequency of F = | f ₁ -f ₂ |.

Signs that coincide with the claimed object: two high-frequency signal generators, a pulse generator, a pulse modulator, a power amplifier, an acoustic antenna.

The reasons that impede the achievement of the technical result are the limited operational capabilities of the locator, due to the fact that the acoustic antenna must be broadband, since it must emit an acoustic signal containing two components with frequencies f ₁ and f ₂ . To expand the antenna bandwidth, it is acoustically damped, which reduces its efficiency in the radiation mode. A power amplifier amplifies the sum of two analog harmonic signals with different frequencies. The level of such a signal varies continuously from zero to the maximum value, which necessitates the operation of the amplifier in the “A” or “B” mode with incomplete use of the supply voltage, low efficiency and high power dissipated on the active elements of the amplifier. The maximum level of the signal supplied to the acoustic antenna is equal to twice the amplitudes of the high-frequency signals and is limited by the mechanical strength of the used piezoceramics and the cavitational strength of the location medium (water). Therefore, the power of the acoustic signal emitted in this locator is 4 times less than the power emitted by the antenna for a single-frequency signal.

The parametric locator is also known [2, p. 209-210], using a parametric acoustic emitter containing a high-frequency signal generator and a low-frequency signal generator connected to the inputs of an amplitude balanced modulator, the output of which is connected to the signal input of a pulse modulator, and its control input is connected to the output of a pulse generator. The output of the pulse modulator through a power amplifier is connected to an acoustic antenna that is in acoustic contact with the location medium. The generator of high-frequency signals generates a sinusoidal signal with a frequency f ₀ supplied to one of the inputs of the amplitude modulator, to the second input of which a sinusoidal signal with a frequency F <f _{0 is} supplied from the generator of low-frequency signals. From the output of the amplitude modulator, the amplitude-modulated voltage of frequency f _{0 is} supplied to a normally closed pulse modulator, which is periodically opened by a video pulse coming from the output of the pulse generator. The pulses of high-frequency amplitude-modulated oscillations come from the output of the pulse modulator to the input of the power amplifier, and from its output to an acoustic antenna that is in acoustic contact with the location medium. The amplitude-modulated high-frequency oscillations are emitted into the location medium, the spectrum of which contains two harmonic components with frequencies f ₀ + F and f ₀ -F [4]. When such a signal propagates in water, these frequency components interact and an acoustic low-frequency signal with a frequency of 2F is formed.

Signs that coincide with the claimed object: high-frequency generator, pulse generator, pulse modulator, power amplifier, acoustic antenna.

The reasons that impede the achievement of the technical result are the limited operational capabilities of the locator, which are the same as the previous locator.

Parametric acoustic locators are free from some of these shortcomings [2 p. 209, 6], the emitting paths of which contain two generators of high-frequency signals with frequencies f ₁ , the outputs of which are connected respectively to the inputs of the first and second pulse modulators, the control inputs of the modulators are connected to the output of the pulse generator. The outputs of the pulsed modulators through power amplifiers are connected to the elements of a two-frequency acoustic antenna in acoustic contact with the location medium. A two-frequency antenna is a mosaic of piezoelectric elements with resonant frequencies f ₁ and f ₂ installed on the base in a common housing [5, p. 189-190]. The first high-frequency generator generates a sinusoidal signal with a frequency f ₁ supplied to the input of the first pulsed normally closed modulator, the second high-frequency generator produces a signal with a frequency f ₂ supplied to the input of the second pulsed normally closed modulator. The pulse generator generates periodically repeating video pulses arriving at the control inputs of the modulators and allowing the passage of high-frequency signals through them, which are then fed to the inputs of two power amplifiers, and from their outputs to the elements of an acoustic antenna emitting acoustic signals with frequencies f ₁ and f ₂ . In the location environment, these signals interact and form a low-frequency signal with a frequency of F = | f ₁ -f ₂ |. In this locator, each of the power amplifiers amplifies a harmonic signal of only one frequency, which has a constant amplitude. Therefore, they can operate in mode "B" with full use of the supply voltage or in mode "D" with low power dissipation on the active elements of amplifiers and with a high efficiency. In addition, the piezoelectric elements of a two-frequency acoustic antenna operate at their resonant frequencies with a high value of electro-acoustic efficiency.

Signs that match the claimed object: high-frequency generators, pulse generator, pulse modulators, power amplifiers, acoustic antenna.

The reasons that impede the achievement of the technical result are the limited operational capabilities of the locator, due to the fact that the piezoelectric elements of each high frequency occupy half the total area of the acoustic antenna, the energy of the acoustic signal emitted into the medium is distributed over the entire area of the antenna, as a result of which the intensity of the acoustic signal for each frequency decreases twice. In addition, individual piezoelectric elements of different frequencies in the transducer are located in close proximity to each other, which leads to a significant influence of them on each other. As a result of this, the resistance of the piezoelectric elements connected to the outputs of the power amplifiers varies widely, and in some cases it can take a negative value, which significantly reduces the reliability of the amplifiers and increases the requirements for them in terms of peak power output. The manufacture of such a two-frequency acoustic antenna is very labor intensive, since it consists of a large number of piezoelectric elements with different frequencies. The acoustic antenna has a finished design and during operation its parameters cannot be changed if necessary.

Locating systems with similar radiating parametric paths are also proposed in patents [7-14].

Closest to the claimed invention is a device for generating short acoustic pulses with parametric radiation and variants of its implementation [10], comprising two high-frequency signal generators, the output of each of which is connected to the signal input of the corresponding pulse modulator, the control inputs of the modulators are connected to the output of the pulse generator, the output of each modulator through a power amplifier is connected to the input of the acoustic antenna.

Signs that match the claimed object: high-frequency generators, pulse generator, pulse modulators, power amplifiers, acoustic antenna.

The limited operational capabilities of this locator are due to the fact that the piezoelectric elements of each high frequency occupy half the total area of the acoustic antenna, and the energy of the acoustic signal emitted into the medium is distributed over the entire area of the antenna, as a result of which the intensity of the acoustic signal for each frequency is halved. In addition, individual acoustic elements of different frequencies in the transducer are located in close proximity to each other, which leads to a significant influence of them on each other. As a result, the resistance of the acoustic elements connected to the outputs of the power amplifiers varies widely, and in some cases it can take a negative value, which leads to a significant decrease in the reliability of the amplifiers and an increase in the peak power output. The manufacture of such a two-frequency acoustic antenna is very laborious, since it consists of a large number of acoustic elements with different frequencies. The acoustic antenna has a finished design, and during operation its parameters cannot be changed if necessary.

The objective of the invention is the creation of a radiating path parametric sonar with wide operational capabilities.

The technical result of the invention is to eliminate the influence of the elements of different frequencies of the acoustic antenna on each other, simplify the design and reduce the complexity of manufacturing the antenna, change its design so that, if necessary, it is possible to vary the characteristics of the locator within the required limits.

The technical result is achieved by the fact that in the radiating path of the parametric sonar containing high-frequency signal generators, the output of each of which is connected to the signal input of the corresponding pulse modulator, the control inputs of the modulators are connected to the corresponding output of the pulse generator, the output of each modulator is connected to the elements of one of the frequencies of the acoustic antenna, the elements of the acoustic antenna of each frequency are located on a separate input of an acoustic waveguide, the waveguide inputs are not acoustically interconnected and acoustically connected to the waveguide output that is in acoustic contact with the location medium, while the number of high-frequency signal generators, their corresponding pulse modulators, power amplifiers and elements of one of the frequencies of the acoustic antenna is equal to or more than two .

The emitting path of a parametric sonar in one embodiment may comprise n high-frequency signal generators, n corresponding pulse modulators, n power amplifiers, n elements of the same frequency of the acoustic antenna and n inputs of the acoustic waveguide, where n is equal to or more than two.

The invention is illustrated by drawings, where in FIG. 1 shows a block diagram of a radiating path of a parametric sonar, and FIG. 2 - design of an acoustic sonar antenna.

The radiating path of a parametric sonar contains 2 or n high-frequency signal generators 1 (1-1, 1-2, ... 1-n, where n is equal to or more than two), the output of each high-frequency signal generator 1 is connected to the signal input of the corresponding pulse modulator 2 (2 -1, 2-2, ... 2-n), the control inputs of all pulse modulators are connected to the output of the pulse generator 3, and the outputs of the pulse modulators 2 through power amplifiers 4 (4-1, 4-2, ... 4-n) elements 5 of the acoustic antenna 6 (elements 5-1 of one frequency, elements 5-2 of another frequency you ... members 5-n - n-th frequency) components of each frequency acoustic antenna arranged on the separate input acoustic waveguide 7, inputs 7 waveguide acoustically not interconnected and acoustically coupled to the output waveguide acoustically connected with the environment of locating 8.

Each of the generators of high-frequency signals 1 generates a sinusoidal signal with a frequency f ₁ , f ₂ , f ₃ ... f _n (individual frequencies f _i can be equal to each other), supplied to the signal inputs of normally closed pulse modulators 2. To the control inputs of pulse modulators 2 periodically repeating video pulses coming from the output of the pulse generator 3, allowing the passage of high-frequency signals through modulators. The repetition period and duration of video pulses are determined by well-known expressions [16, p. 108-110]. The radio pulses from the outputs of the pulse modulators 2 after amplification by power amplifiers 4 are supplied to the elements 5 of the acoustic antenna 6, emitting acoustic signals with frequencies f ₁ -f _n into the acoustic waveguide 7. In the acoustic waveguide 7, the summation of these acoustic signals and their subsequent emission into the location medium 8 occurs. The number of frequencies f _{i of the} signals generated by the generators 1 can be equal to two or more than two. The acoustic waveguide 7, as shown in FIG. 2, structurally has n acoustically unconnected inputs that are acoustically connected to the output of the waveguide. Thus, it sums up the acoustic high-frequency signals emitted by the elements 5 of the acoustic antenna 6. On the location medium 8, acoustic high-frequency signals of several frequencies are emitted, propagating simultaneously in the same sections of the medium 8. Since real media (liquids, gases, solids) bodies) possess nonlinearity of their elastic characteristics, then when high-frequency signals of several frequencies propagate in them, their interaction and the formation of low-frequency signals in with frequencies F _k = | f _i -f _j |. Including certain high-frequency oscillators 1, it is possible to obtain various values of the frequencies F _{k of} low-frequency signals. Each of the elements 5 of the acoustic antenna 6 operates at a single frequency. Replacing them with elements of a different frequency, it is possible to modernize the entire radiating path of the locator without any difficulties. Structurally, there is no acoustic coupling between elements 5 of different frequencies, which facilitates the operation of power amplifiers 4, since they operate on a load with constant resistance. The waveguide 7 can be made of a material that acoustically agrees well with the location medium 8. Such materials for the location medium 8 - water can be sound-transparent compounds, for example, two-component polyurethane elastomer SPB-KhP-80 (TU224-001-20507988-2003), or prepolymer SKU-PFL-100 with hardener or vulcanized rubber. Also, the waveguide can be made in the form of the volume of the medium 8, bounded by acoustically rigid or acoustically soft walls. By performing the elements of the waveguide 7 with a variable cross-section, it is possible to obtain an increase in the intensity of acoustic high-frequency signals or to perform their necessary coordination with the elements 5 of the acoustic antenna 6 or with the location medium 8 [15].

In the prototype, an acoustic antenna consists of a large number of acoustic elements of different frequencies, distributed and fixed on the base and located in a common housing. Since the number of these individual elements for a medium-sized acoustic antenna can reach several hundred, and the installation of each of them requires soldering and fixing to the base at predetermined locations, the assembly of such an acoustic antenna is highly labor intensive, and its design cannot be further modified.

In the present invention, to simplify the design and reduce the complexity of manufacturing the radiating path of a parametric sonar, an acoustic antenna is made in the form of a set of individual elements of the same frequency, each of which is located on a separate input of the acoustic waveguide, the output of which is directly connected to the location medium. Moreover, the design and installation of these elements is greatly simplified, since all elements located nearby at each of the waveguide inputs have the same frequency. Therefore, their number can be reduced. In the limit, it can be one piezoelectric plate operating at its resonant frequency. The absence of the mutual influence of elements of different frequencies, achieved by using an acoustic waveguide, allows you to reduce the requirements for power amplifiers and increase the reliability of their work.

When switching to other values of the frequencies of high-frequency signals or an acoustic signal, it is sufficient to replace only the acoustic elements of the corresponding frequency, which is not associated with any difficulties. This greatly increases the operational capabilities of the claimed device.

Unlike the prototype, where acoustic elements of the same frequency occupy half the total area of the acoustic antenna, and the energy of the acoustic signal is distributed over its entire area, which leads to a decrease in the intensity of the acoustic signal of each frequency by half, in the inventive device, elements of the same frequency occupy the entire input area acoustic waveguide acoustic antenna. As a result of this, the intensity of the high-frequency signal for each source frequency doubles, and the level of the acoustic signal of the difference frequency increases 2-4 times with the same load on the elements of the acoustic antenna. When more than two high-frequency signals interact, the level of difference-frequency signals increases even more. This allows you to increase the range of location, or at the same distances to detect objects with smaller sizes, which increases the operational capabilities of the claimed device.

Thus, in the proposed device as a result of the introduction of new blocks and connections: namely, an acoustic waveguide located between the elements of the acoustic antenna and the location medium is achieved:

- elimination of the influence of elements of different frequencies of the acoustic antenna on each other;

-simplification of the design and reducing the complexity of manufacturing an acoustic antenna;

- facilitation of the mode of operation of locator power amplifiers;

- the possibility of forming a low-frequency acoustic signal in a wide frequency band by changing the parameters of the radiating path of a parametric sonar.

The present invention contributes to the creation of a radiating path parametric sonar with enhanced operational capabilities and a simplified design, while reducing the complexity of its manufacture.

Information sources

1. Zarembo L.K., Krasilnikov V.A. Introduction to nonlinear acoustics. M .: Nauka, 1966 .-- 418 p.

2. Novikov B.K., Timoshenko V.I. Parametric antennas in sonar. - L .: Shipbuilding, 1989 .-- 256 p.

3. Novikov BK, Rudenko OV, Timoshenko V.I. Nonlinear sonar. L .: Shipbuilding, 1981.-261 p.

4. Gonorovsky I.S. Radio circuits and signals. M .: Sov. Radio, 1986 .-- 512 s.

5. Voronin V. A., Kuznetsov V. P., Mordvinov B. G., Tarasov S. P., Timoshenko V. I. Nonlinear and parametric processes in the acoustics of the ocean. - Rostizdat. Rostov-on-Don. 2007 .-- 448 p.

6. Patent US 4308599 "Parametric dual-frequency sonar", IPC G01S 15/02, G01S 15/10, G01S 15/87, published 05/19/1980.

7. Patent US 5790474 "Active sonar for work in ice conditions", IPC G01S 15/06, G01S 15/10, G01S 7/539, G01S 15/87, published 08/04/1989.

8. Patent US 3763463 "Locator for the detection of foreign inclusions", IPC A61 B8 / 08; G01S 15/04; G10K 11/00, published 09/21/1972.

9. Patent DE 3113261 "Echo sounder", IPC G01S 15/60, published October 21, 1982.

10. Patent RU 2390797 "Method for the formation of short acoustic pulses with parametric radiation and options for its implementation", IPC G01S 15/00, G01S 7/524, published 05/27/2010.

11. Patent RU 2205420 "Parametric acoustic locator", IPC G01S 13/32, G01S 15/02, G01N 29/04, published 05.27.2003.

12. Patent RU 2133047 "Parametric echo-pulse locator", IPC G01S 15/60, published July 10, 1999.

13. Patent RU 69646 "Parametric echo-pulse locator", IPC G01S 15/60, G01N 29/04, published December 27, 2007.

14. Patent RU 2011205 "Parametric echo sounder", IPC G01S 15/00, published 04/15/1994.

15. Isakovich M.A. General acoustics. M .: Nauka, 1973.- 496 p.

16. Kobyakov Yu.S., Kudryavtsev N.N., Timoshenko V.I. Design of sonar fishing equipment. - L .: Shipbuilding. 1986.- 272 p.

Claims (1)

The radiating path of a parametric sonar containing high-frequency signal generators, the output of each of which is connected to the signal input of the corresponding pulse modulator, the control inputs of the modulators are connected to the corresponding output of the pulse generator, the output of each modulator is connected to the elements of one of the frequencies of the acoustic antenna, characterized in that the elements of the acoustic antenna of each frequency are located on a separate input of the acoustic waveguide, in the waveguide moves are not acoustically interconnected and acoustically connected to the waveguide output that is in acoustic contact with the location medium, while the number of high-frequency signal generators, corresponding pulse modulators, power amplifiers, and elements of one of the frequencies of the acoustic antenna is equal to or more than two.

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