RU2582898C2 - Generating 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 generating channel of parametric sonar comprises a pulse generator, two high-frequency signal generators, the output of each of which is connected to the signal input of the corresponding pulse modulator, the outputs of the pulse modulators are connected through power amplifiers to acoustic antenna elements. The channel further includes a multiplier, two inputs of which are connected to outputs of the high-frequency signal generators, the output of the multiplier is connected through series-connected low-pass filter and comparator to the control input of a D flip-flop, the data input of which is connected to the output of the pulse generator, and the output of the D flip-flop is connected to control inputs of the pulse modulators.

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]. 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. 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 sonars [2, 3], the generator paths of which contain two generators of high-frequency signals, the outputs of which are connected to two inputs of the adder, the output of which is connected to the signal input of a normally closed pulse modulator. The control input of the pulse modulator is connected to the output of the pulse generator, and the output through the power amplifier is connected to an acoustic antenna.

The first high-frequency generator generates a sinusoidal signal with a frequency f ₁ , and the second - 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 the acoustic antenna.

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 low accuracy of measuring the distance to the detected objects and signal levels reflected from them, the lack of a reference voltage with the frequency of the low-frequency sounding signal. This is because the power amplifier amplifies the sum of two analog harmonic signals with different frequencies. The amplitude of such a signal varies from zero to a double value of the amplitudes of the original harmonic signals. The power amplifier for undistorted amplification of such a signal should work in mode "A" or in mode "B" with incomplete use of the supply voltage. These modes are characterized by a low efficiency and high power dissipated on the active elements of the amplifier. In addition, in these sonars, the high-frequency signals supplied to the acoustic antenna have a random initial phase. This is because the high-frequency signal generators and the pulse generator operate independently of each other, as a result of which the leading edge of the video pulse opening the pulse modulator can coincide with any part of the high-frequency signals, as a result of which the radio pulses at their outputs can begin from any initial phase. When high-frequency components of the probing signal with different initial phases are applied to the acoustic antenna, the shape of the envelope and the phase structure of the emitted high-frequency acoustic signals will change. This leads to the fact that low-frequency acoustic signals formed in the location medium, as well as low-frequency echo signals for different location cycles, will have a random initial phase. When passing the voltages of low-frequency echo signals with different initial phases in different locating cycles through selective systems of the receiving path, the envelope shape and phase structure will also change [4], which leads to additional errors in determining the arrival time and amplitude of the echo signals for different location cycles . After detecting such radio pulses, video pulses with different steepness of the fronts are obtained, which gives an additional error in determining the time intervals between the beginning of the location cycle and the time of arrival of the echo pulse. In addition, in the pause between parcels in the generator path, there is no reference signal with the frequency of the low-frequency sounding signal, the use of which in the receive path can determine the Doppler frequency shift of the echo signals [5]. Similar generator paths and parametric acoustic locators proposed in the patents [6-8].

. В данном локаторе каждый из усилителей мощности усиливает гармонический сигнал только одной частоты, имеющий постоянную амплитуду. Поэтому они могут работать в режиме «В» или «D» с малыми мощностями рассеивания на активных элементах усилителей и с высоким коэффициентом полезного действия.In a parametric acoustic locator [1, p.209], having the greatest number of matching features with the claimed device and taken as a prototype, the emitting path contains two high-frequency signal generators, 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 pulse generator output. Each of the outputs of the pulse modulator through a power amplifier is connected to elements of an acoustic antenna in acoustic contact with the location medium. An acoustic antenna is a mosaic of piezoelectric elements with resonant frequencies f ₁ and f ₂ installed in a common housing [9, 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 generates a sinusoidal signal with a frequency f ₁ 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 . When propagation in the medium of the location, as a result of the nonlinearity of its elastic characteristics, the interaction of these signals and the formation of a low-frequency signal with a difference frequency $$\text{F}=\text{| f1-f2 |}$$

. 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 the "B" or "D" mode with low power dissipation on the active elements of the amplifiers and with a high efficiency.

However, in this locator, the radio pulses generated at the output of the pulse modulators also have an arbitrary initial phase in the range 0-2π. This is due to the fact that the high-frequency signal generators and the pulse generator operate independently of each other, therefore, the leading edge of the video pulse opening the pulse modulators can coincide with any part of the high-frequency signals. This leads to the fact that when applying the high-frequency components of the probing signal with an arbitrary initial phase to the acoustic antenna for different probing cycles, the envelope and phase structure of the emitted acoustic signals will change. The low-frequency acoustic signal and echo signals generated in the location medium will also have a random initial phase.

When low-frequency echo signals pass through selective systems of resonant amplifiers of the radar receiver path, the envelope and phase structure of the echo signals also change [4], which leads to additional errors in determining the arrival time and amplitude of the echo signals for different location cycles. In the pause between the sending of the probe signals in the generator path, there is no generation of the reference signal with the frequency of the low-frequency probe signal, necessary, for example, to determine the Doppler frequency shift of the echo signals [5].

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 low accuracy of measuring the distance to the detected objects and signal levels reflected from them, the lack of a reference voltage with the frequency of the low-frequency sounding signal. This is due to the fact that the radio pulses generated at the output of the pulse modulators have an arbitrary initial phase in the range 0-2π. The low-frequency acoustic signal generated in the location medium and the echo signals will have a random initial phase. After detecting the echo signals, video pulses with different steepness of the fronts are obtained, which will give an additional error in determining the time intervals between the beginning of the location cycle and the time of arrival of the echo pulse. When low-frequency echo signals pass through selective systems of resonant amplifiers of the receiving path of the locator, the envelope and phase structure of the echo signals will also change [4], which leads to additional errors in determining the arrival time and amplitude of the echo signals for different location cycles. In the pause between the sending of the probe signals in the generator path, there is no generation of the reference signal with the frequency of the low-frequency probe signal, necessary, for example, to determine the Doppler frequency shift of the echo signals [5].

The objective of the invention is the creation of a generator path of a parametric locator with increased accuracy of measuring the distance to detected objects and signal levels reflected from them, and providing the formation of a reference voltage with a frequency of a low-frequency sounding signal.

The technical result of the invention is to eliminate errors that occur when measuring the distance to the detected objects and signal levels reflected from them, due to the non-identity of the generated probing signals for different location cycles.

An additional technical result consists in the formation of a reference voltage with a frequency of a low-frequency sounding signal.

The technical result is achieved by the fact that in the generator path of the parametric locator containing a pulse generator, two high-frequency signal generators, the output of each of which is connected to the signal input of the corresponding pulse modulator, the outputs of the modulators through power amplifiers are connected to the elements of the acoustic antenna, an additional multiplier, two inputs are introduced which are connected to the outputs of the high-frequency signal generators, and the output of the multiplier through a series-connected low-pass filter frequency and the comparator is connected to the control input of the D-trigger, the data input of which is connected to the output of the pulse generator, and the output of the D-trigger is connected to the control inputs of the pulse modulators.

The elimination of errors arising in measuring the distance to the detected objects, signal levels reflected from them, and the formation of sounding signals for different location cycles is achieved by generating high-frequency components of the probe signal, which are identical for different location cycles, by forming low-frequency components as a result of their interaction in the location environment acoustic signals with the same parameters.

The invention is illustrated by drawings, where

in FIG. 1 shows a block diagram of a generator path of a parametric locator;

in FIG. Figure 2 shows stress plots at various points.

The parametric sonar generator path contains: a high-frequency signal generator 1, the output of which is connected to the signal input of the pulse modulator 2 and one of the inputs of the multiplier 3. The output of the second high-frequency generator 4 is connected to the signal input of the second pulse modulator 5 and with the second input of the multiplier 3. Output of the multiplier 3 through a series-connected low-pass filter 6 and a comparator 7 is connected to the control input of the D-trigger 8, the data input of which is connected to the output of the pulse generator a 9. The output of the D-flip-flop 8 is connected to the control inputs of the pulse modulators 2 and 5, and the outputs of the modulators 2 and 5 through power amplifiers 10 and 11 are connected to the elements 12 and 13 of the acoustic antenna 14.

The generator path of the parametric sonar operates as follows.

High-frequency signal generators 1 and 4 produce sinusoidal signals U1 and U2 with frequencies f1 and f2, respectively, which are fed to the signal inputs of normally closed pulse modulators 2 and 5 and to two inputs of multiplier 3. At the output of multiplier 3, we obtain voltage U3, which will be equal to

U3 = U1cos (ω ₁ t) * U2cos (ω ₂ t) = ½U1 * U2 [cos (ω ₁ -ω ₂ ) t + cos (ω ₁ + ω ₂ ) t].

The voltage U3 is supplied to a low-pass filter 6, filtering the high-frequency component of the signal. The voltage U4 at the output of the filter 6 will be equal to

U4 = ½U1 * U2cos (ω ₁ -ω ₂ ) t.

Further, the voltage U4 is supplied to the input of the comparator 7, at the output of which video pulses U5 are generated corresponding to any part of the harmonic signal U4, for example, to its half-waves of positive polarity, as shown in FIG. 2, then fed to the dynamic control input of the D-flip-flop 8. The D-flip-flop 8 data input from the pulse generator 9 receives video pulses U6 that determine the duration and repetition period of the generated probing signal, which depend on the location conditions [10, p. 108-110 ].

At the output of the D-trigger, video pulses U7 are formed, the beginning and end of which will correspond to the leading edges of the video pulses U5 formed in the comparator 7, that is, in the same phase of the signal U4. These video pulses arrive at the control inputs of normally closed pulse modulators 2 and 5, open them, as a result of which at the output of the modulators radio pulses U8 and U9 are formed, which then go to the inputs of power amplifiers 10 and 11, and from their outputs to the acoustic elements 12, 13 antennas 14. The radio pulses U8 and U9 for different location cycles will have the same initial phase.

. Причем при постоянных параметрах исходных высокочастотных сигналов (форма огибающей и фазовая структура) для разных циклов лоцирования этот сигнал будет иметь также постоянные параметры, а именно форму огибающей, значения начальной и конечной фаз для разных циклов лоцирования.Elements 12 and 13 of the acoustic antenna 14 emit high-frequency acoustic signals with frequencies f ₁ and f ₂ into the location medium. Since real media (liquids, gases, solids) have a non-linearity in their elastic characteristics, then when high-frequency signals with different frequencies f ₁ and f ₂ propagate in them, they will interact and form a low-frequency probe signal with a frequency $$\text{F}=\text{| f1-f2 |}$$

. Moreover, with constant parameters of the initial high-frequency signals (envelope shape and phase structure) for different location cycles, this signal will also have constant parameters, namely the shape of the envelope, the values of the initial and final phases for different location cycles.

In FIG. 1 and FIG. 2, voltage U10 is equivalent to a probing signal generated in the location medium.

The voltage U4 generated from the electrical signals U1, U2 has the same frequency as the acoustic probe signal generated in the location medium from high-frequency acoustic signals with frequencies f ₁ and f ₂ . Thus, the voltage U4 can be used as a reference, for example, to determine the frequency of the Doppler shift of the echo signals [5]. The low-frequency sounding signal is generated from the acoustic high-frequency signals emitted by the acoustic antenna 14 into the location medium identical to the high-frequency radio pulses U8 and U9. Therefore, having received voltage U10 with a constant initial and final phase for different locations, we obtain low-frequency sounding signals generated in the location environment, also with constant parameters - envelope shape, initial and final phases.

Thus, as a result of introducing new blocks and connections into the known device, it was possible to generate probing low-frequency signals with constant values of the initial and final phases, and also a reference signal equal in frequency to the acoustic probing signal in parametric locators, which made it possible to increase the accuracy of determining the distance to the detected objects and determine the frequency of the Doppler shift of the echo signals.

Hardware implementation of the proposed device is not difficult. In the circuit design of all its blocks, standard analog and digital elements can be used. For example, generators 1 and 4 can be built on operational amplifiers or transistors according to known schemes [11], pulse generator 9 can be implemented on any digital inverters - K561LN2, K1533LN1, multiplier 3 - on microcircuits K140MA1, K525PS1, pulse modulators 2 and 5 - on K561KT3, K561KP1, K190KT2 analog key microcircuits, comparator 7 - on K554CA3, K554CA4 microcircuits, trigger 8 - on K561TM2, K555TM2 microcircuits, low-pass filter 6 - on any passive or active low-pass filters.

The proposed technical solution contributes to the creation of the generator path of the parametric locator, which has increased accuracy of measuring the distance to the detected objects and the signal levels reflected from them and provides the formation of a reference voltage with a frequency of a low-frequency sounding signal.

Information sources

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

2. Patent RU 2133047. "Parametric echo-pulse locator". IPC G01S 15/60, publ. 07/10/1999.

3. Patent UA 74833. "Parametric profiler." IPC G01S 15/00, publ. 02/15/2006.

4. Zolotarev I.D. "Transient processes in resonant amplifiers of phase-pulse measuring systems." Novosibirsk: Nauka, 1969 .-- 176 p.

5. Bukaty V.M., Dmitriev V.I. Hydroacoustic logs. - M.: Food Industry, 1980. - 176 p.

6. Patent RU 2390797. “Method for the formation of short acoustic pulses with parametric radiation and device implementation options”. IPC G01S 15/00, G01S 7/524, publ. 05/27/2010.

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

8. Patent DE 3113261. "Sounder." IPC G01S 15/60, publ. 10/21/1982.

9. 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.

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

11. Golub B.C. Harmonic generators. - M .: Energy, 1980. - 80 p. - (B-k on electronics; Issue 69).

Claims (1)

The generator path of the parametric locator containing a pulse generator, two high-frequency signal generators, the output of each of which is connected to the signal input of the corresponding pulse modulator, the outputs of the pulse modulators through power amplifiers are connected to the elements of an acoustic antenna, characterized in that a multiplier, two inputs are additionally introduced into it which is connected to the outputs of the high-frequency signal generators, the output of the multiplier through a series-connected low-pass filter is often and a comparator coupled to the control input of the D-flip-flop whose data input connected to the output of the pulse generator, and the output of D-flip-flop is connected to the control inputs of pulse modulators.

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