RU2048678C1 - Direction finder of acoustic wave sources - Google Patents

Abstract

FIELD: navigation and acoustic wave direction finding. SUBSTANCE: direction finder provides for scanning movable acoustic (hydroacoustic) wave source by means of its directivity pattern. EFFECT: improved design, eliminated operation of direction finder in response to localized low-band moving interferences. 10 dwg

Description

 The invention relates to the field of location and navigation and can be used in information-measuring tools and location systems operating in passive detection and direction finding of acoustic radiation.

 A device for detecting acoustic signals is known, comprising two channels of signal pre-processing, each of which consists of a series-connected acoustic sensor, a band-pass filter, an amplifier and a threshold element, an element And, an alarm generator, the outputs of the first and second threshold elements being connected to the corresponding inputs of the element AND.

 When the signals at the output of both signal processing channels exceed the threshold values of the threshold elements, signals appear at both inputs of the AND element, the signal from the output of which turns on the alarm generator.

 The disadvantages of this device are the low accuracy of formation and the inability to control the decision area, as well as the inability to determine the direction of approach to the controlled area of a localized source of the acoustic field, due to the fact that the decision is made by the logical coincidence of exceeding the threshold values of the signals at the outputs of two acoustic sensors having wide radiation patterns.

 A device for the detection and direction finding of electromagnetic waves, containing two processing channels, each of which consists of receiving antennas and resonant amplifiers, is introduced into the first channel phase shifter at π / 2, as well as a phase detector and voltmeter.

 After receiving the signals and amplifying them, they are fed to a phase detector, and the signal of the first channel is previously phase shifted by π / 2 to improve the steepness of the direction-finding characteristic. The phase separation of the received signal occurs in the detector. The output signal carries information about the presence of an object in the reference direction.

 The disadvantages of this device are the requirement for fine tuning of resonant amplifiers, the absence of which leads to inaccurate determination of the direction to the object and the inability to scan the object with a radiation pattern (LF), as well as the lack of protection against operation by interference.

 The closest in technical essence to the proposed device is a passive direction finder of broadband radiation sources operating in two planes (horizontal and vertical) and consisting of three signal receivers, each of which is connected in series with a bandpass filter, a discrete functional converter, the outputs of which are connected to a discrete converter signals (DPS) connected through an analog signal converter (APS) and a threshold functional signal converter (PFP) ) With the coincidence circuit. At the same time, bandpass filters through the energy channel and the second PFPS are also connected to the matching circuit.

 After reception, the signals are filtered and fed into discrete functional converters. Correlation signal processing is carried out in a discrete signal converter (DPS) and an analog signal converter (APS). If the threshold level of the PFPS is exceeded, an enable signal is issued to the coincidence circuit. The coincidence circuit is opened and the direction finder response signal is issued if an enable signal comes from the second PFPS with an enable signal about the received emissions from the energy channel.

 The disadvantages of this direction finder are the inability to scan the main maximum of the ND when working on moving objects, as well as the possibility of triggering on localized narrow-band mobile noise.

 The purpose of the invention is the ability to scan a movable source of acoustic (or hydroacoustic) radiation of the beam of the device, as well as the exclusion of the possibility of operation of the direction finder by localized narrow-band mobile noise.

 This is achieved by the fact that the direction finder of acoustic radiation sources contains three signal receivers, each of which is connected in series with a bandpass filter, a discrete functional converter, the outputs of which are connected to a discrete signal converter (DPS), connected through an analog signal converter (APS) and PPS with a matching circuit, in parallel having bandpass filter connections through an energy channel and a second PFPS with a matching circuit, the presence of a signal with which indicates operation of the direction finder, after discrete functional converters, delay lines are introduced in the form of shift registers and a control unit for them, as well as a relative bandwidth selector that is switched on in parallel through the matching circuit in the circuit with the energy channel, as well as an intermediate and output key for issuing additional information about angle of direction finding.

 Comparative analysis with the prototype shows that the proposed device is distinguished by the presence of new elements in the circuit: a selector from narrowband interference, delay lines and a control unit for them, as well as their relationships with the indicated circuit elements, intermediate and output keys. Therefore, the device meets the criterion of "novelty."

 Comparison with other technical solutions shows that the direction finder protection against false positives due to moving and stationary narrowband interference is increased. Introduction to the device circuit of delay lines and a control unit for them allows scanning the bottom of the source of acoustic radiation in two planes (horizontal and vertical), which is a new property for passive direction finders of acoustic radiation. The introduction of well-known logical keys allows you to remove additional information about the angle of the bearing of the object.

 This allows us to conclude that the proposed solution meets the criteria of the invention "inventive step".

 In FIG. 1 shows a structural diagram of a direction finder of acoustic radiation; in FIG. 2 direction-finding characteristic of the device at different weight coefficients K regression algorithm; in FIG. 3 the performance of the HPF based on the operational amplifier K157UD1; in FIG. 4 is a structural diagram of the energy channel of the direction finder of acoustic radiation sources; in FIG. 5 block diagram of a discrete signal converter; in FIG. 6 functional diagram of an analog signal converter; in FIG. 7 is a structural diagram of an analog signal converter; in FIG. 8 is a structural diagram of the delay lines and the control unit; in FIG. 9 timing diagrams of the operation of the delay line circuit and their control unit; in FIG. 10 is an electrical concept of delay lines and a control unit for them.

 The direction finder of acoustic radiation sources contains three electro-acoustic transducers of signals 1, spaced in space at a given distance and connected to three combined filters 2, the outputs of which are connected to three discrete functional transducers (DFT) 3, the outputs of which are connected to discrete delay lines 4. The outputs of discrete lines delays are connected to a discrete signal converter (DPS) 5, the output of which is connected to an analog signal converter (APS) 6, the output of which is via horn functional converter (PFPS) 7 is connected to the output key 8. The outputs of the combined filters 2 are also connected to the energy channel 9 and the selector for the relative width of the frequency band 10, the output of which is connected to the matching circuit 11, one of the inputs of which is connected to the output of the energy channel 9 and the output with an intermediate key 12, one of the inputs of which is connected to the control unit 13, which is connected to discrete delay lines 4, and the output with the output key 8.

 Electro-acoustic signal converters 1 with three combined filters 2 form a block of receiving elements and filtering signals 14, discrete functional converters 3 with delay lines 4 and a control unit 13 form a sign processing unit and delay lines 15. Discrete signal converter (DPS) 5 with an analog converter signals (APS) 6, a threshold functional signal converter (PFPS) 7 and an output key 8 form a block of correlation signal processing 16.

 The energy channel 9 with a selector for the relative width of the frequency band 10, a matching circuit 11 and an intermediate key 12 form a unit for detecting and recognizing an object from interference 17.

Consider a specific example of the embodiment of the indicated direction finder circuit of acoustic radiation sources (see Fig. 1), where the electro-acoustic signal transducers 1 are electromagnetic microphones of the DEM type, spaced in each plane of work (horizontal and vertical) by a distance of d 5 λ _o (λ _o length medium frequency waves of the spectrum).

 Combined filters 2 are a combination of two active bandpass filters low-pass and high-pass filters. Filters are built on the principle of sequential inclusion. They have the following characteristics.

Low-pass filter (low-pass filter): passband Δ f _0.7 500 Hz at f _{it is} 350 Hz with a rise rate of K _n 60 dB / dec and a decrease slope K _s = 40 dB / dec.

High-pass filter (HPF): passband Δ f _0.7 750 Hz at f _o 2200 Hz with a rise slope of K _n 20 dB / dec and a fall slope of K _s = 40 dB / dec.

 In FIG. Figure 3 shows an example of a high-pass filter based on the K157UD1 operational amplifier.

 Discrete functional converters (DFP) 3 of the block 15 and the threshold functional signal converter (PFPS) 7 of the block 16 are made on type K554CA3 microcircuits included in a typical way.

 The energy channel 9 of block 15 is represented by an adder 18, a half-wave detector 19, an integrator 20, and a threshold block 21 connected in series (see Fig. 4).

The integrator 20 is built on an RC circuit, the value of the integration time constant τ _{int of} which is selected based on the value of the time t _{n of the} bearing being detected within the main maximum of the beam (see Fig. 2), depending on the speed of the proposed object U _about and the width of the beam. In the general case, τ _int <t _n . In the proposed direction finder, τ _int is 140 ms. The threshold voltage U _{p of the} threshold block 21 is selected based on the dependence U _p σ _c / 3, where σ _{c is the} rms value of the signal at the input of the threshold block 21, depending on the sensitivity S _{e of the} electro-acoustic transducers 1 and the sound pressure P _sound incident on them. In the proposed direction finder U _p 300 mV.

The transistor KT315 is used as an intermediate key 12 of block 17 and the output key 8 of block 16 (you can use the AMC of the K590 series)
Match pattern 11 of block 17 (see Fig. 1) is implemented on element I.

U_o[2·1(t)-K_сζ(t)] dt≥ U_п (1) где τ_н постоянная времени инерционной цепи селектора, выбранная исходя из τ_н >> Т_т, в нашем случае τ_н 0,08 с;
Т_т π / ω_o тактовые интервалы клиппированного случайного процесса ζ (t) на центральной частоте спектра;
К_с весовой коэффициент алгоритма работы селектора (К_с 1,2 ÷ 1,5);
U_о амплитуда импульсов случайного импульсного процесса;
Т длительность реализации;
1(t) единичная функция;
U_п пороговый уровень, который выбирается исходя из относительной полосы α энергетического спектра процесса и от параметра К, для нашего случая U_п 200 ÷ 300 мВ).The selector for the relative frequency bandwidth of the input process 10 is made in the form of a discrete analog system with pulse width modulation (PWM), processing the intervals between the zeros of the input implementations, in which a regression algorithm of the form

U _o [2 · 1 (t) -K _with ζ (t)] dt≥ U _p (1) where τ _n is the time constant of the inertial circuit of the selector, selected on the basis of τ _n >> T _t , in our case τ _n 0, 08 s;
T _t π / ω _o clock intervals of the clipped random process ζ (t) at the center frequency of the spectrum;
K _{with the} weight coefficient of the algorithm of the selector (K _with 1.2 ÷ 1.5);
U _{about the} amplitude of the pulses of a random pulse process;
T is the duration of the implementation;
1 (t) unit function;
U _p threshold level, which is selected based on the relative band α of the energy spectrum of the process and on the parameter K, for our case U _p 200 ÷ 300 mV).

 DPS 5 of block 16 consists of two logical elements AND 22 and 23, two logical elements OR NOT 24 and 25, three logical elements OR 26, 27 and 28 (see Fig. 5).

6 MTA block 16 (see. FIG. 7) is composed of analog switches 29 and 30, adder 31 and integrator 32, formed on the RC-circuits (R3C and R4c when R3 R4 >> R2 and τ τ _{uA Int} energy channel integrator block 9 15, τ _uA 140 ms (see. FIG. 6).

 The delay lines 4 and the control unit 13 of block 15 contain (for the first pair of channels operating in the same plane: for a pair of channels operating in the perpendicular plane, the execution is identical) input (МС1) multiplexer 33, shift register (RG) 34, delayed signal multiplexer ( MS3) 35, output multiplexer (MS2) 36, a circuit for generating an address code and control signals (F) 37 (see FIG. 8). Elements of the circuit 33 37 are implemented on the IS 564 series.

 The direction finder of the source of acoustic radiation works as follows.

sinθ_d/v где θ_g/v угол между опорным направлением источника акустического поля (в зависимости от сканирующей плоскости горизонтальная или вертикальная) и текущим положением;
d_g/v расстояние между электроакустическими преобразователями сигналов (в горизонтальной или вертикальной плоскостях);
с скорость звука.When a localized source of the acoustic field enters the coverage area (radiation pattern) of the electro-acoustic signal transducers 1, the combined filters 2 receive phase difference signals Δ φ _{g / v} (f) at a given frequency f in each scanning plane (horizontal or vertical, g / v) due to the difference in the course of acoustic waves to electro-acoustic signal transducers 1 is determined in the form:
Δφ _{d / v} (f)

sinθ _{d / v} where θ _{g / v is the} angle between the reference direction of the source of the acoustic field (depending on the scanning plane, horizontal or vertical) and the current position;
d _{g / v} distance between electro-acoustic signal transducers (in horizontal or vertical planes);
with the speed of sound.

y(t)=f[η(t)]

(2)
z(t)= f[γ(t)]

где ζ (t), η (t), γ (t) сигналы до и x(t), y(t), z(t) сигналы после функционального преобразования в ДФП 3 соответственно в каждом из каналов.To reduce the influence on the accuracy of direction finding of instabilities of transmission coefficients of paths and to expand the dynamic range, the signals after filtering undergo a functional transformation of the form
x (t) = f [ζ (t)]

y (t) = f [η (t)]

(2)
z (t) = f [γ (t)]

where ζ (t), η (t), γ (t) are signals up to and x (t), y (t), z (t) are signals after functional conversion to DFT 3 in each channel, respectively.

E(t)[F_Σ(t)-K·F_v(t)]dt≥ 0 (3) где Т время принятия решения, выбирается исходя из времени наблюдения t_н, которое зависит от угла сканирования объекта; при θ_ск ± 60^о и U_об= 100 м/c, Т 40 с на дальностях до 2 км;
Е(t) напряжение питания на интервале принятия решения Е(t) E const +-12 В;
F_Σ (t) функция алгебры логики, отражающая знакосовпадение квантованных сигналов во времени, а следовательно, совпадение фаз сигналов на каждой частоте на входах ДФП 3;
F_v(t) функция алгебры логики, отражающая знаконесовпадение квантованных сигналов во времени на каждой частоте на входах ДФП 3;
К коэффициент регрессионного алгоритма, определяющий ширину области срабатывания пеленгатора (см. фиг. 2) и пороговый уровень U_п; для К 1 2, U_п 0 В.Correlation processing, which forms the decision-making area, is carried out in DPS 5 and APS 6 according to the regression algorithm for joint comparison of the signals of the coincidence signals at the output of three electro-acoustic signal transducers 1 after filtering in combined filters 2 and functional transformation (2) into DFP 3 (see Fig. 1) in the following form:

E (t) [F _Σ (t) -K · F _v (t)] dt≥ 0 (3) where T is the decision time, is selected based on the observation time t _n , which depends on the scanning angle of the object; at θ _ck ± 60 ^о and U _r = 100 m / s, T 40 s at ranges up to 2 km;
E (t) supply voltage at the decision interval E (t) E const + -12 V;
F _Σ (t) the function of the algebra of logic, reflecting the sign coincidence of the quantized signals in time, and therefore, the coincidence of the phases of the signals at each frequency at the inputs of the DFT 3;
F _v (t) is a function of the algebra of logic, reflecting the sign mismatch of the quantized signals in time at each frequency at the inputs of the DFT 3;
To the coefficient of the regression algorithm that determines the width of the area of operation of the direction finder (see Fig. 2) and the threshold level U _p ; for K 1 2, U _p 0 V.

The value of F _Σ (t) is formed by a chain of elements And 22 and 23, OR NOT 24 (see Fig. 5) and analog key 29 (see Fig. 7); the value of F _v (t) is formed using a chain of elements And 22 and 23, OR NOT 24 and 25, OR 26, 27, 28 (see Fig. 5) and an analog key 30 (see Fig. 7).

 The coefficient K of the regression algorithm (3) is set by resistors R1 and R2 (see Fig. 6).

The work of the discrete-analog regression algorithm (3), carried out in DPS 5 and APS 6 of block 16, consists in the following: when the signals coincide on the control inputs of analog keys 29 and 30 (see Fig. 7), the function of the algebra of logic F _v (t) vanishes, and when the signals are inconsistent, the function of the algebra of logic F _Σ (t) vanishes.

 Thus, when a localized source of an acoustic field enters the decision-making region (direction-finding characteristic) of the DFT 3 (see Fig. 2), the signals at the inputs at each reception frequency practically coincide in phase (time-aligned). In this case, the function of the algebra of logic Fv (t) vanishes, then the signal at the output of the resistor R2 (see Fig. 6) is close to zero. In this case, the signal from the output of the controlled key 29, passing through the adder 31 and the integrator 32 (see Fig. 7), is sufficient to trigger the threshold element 7 (see Fig. 1).

 The triggering of element 7 is used as a fact of the direction finder Z operation. The signals from the combined filters 2 are simultaneously sent to the energy channel 9 and the selector according to the relative width of the frequency band 10. If the received signals are sufficient in their energy level and do not belong to the "Interference" class in their frequency band , then a signal appears at the output of the matching circuit And 11, which opens the intermediate key 12, the input of which is fed a signal from the control unit of the delay lines 13, containing information about the scanning angle. As a result of this, a signal appears at the output of the output key 8 of block 16 (see Fig. 1), which carries information about the angular position of the source of acoustic waves θ.

 When the direction finder Z is triggered during operation by narrowband interference, the signal θ carrying information about the angle of the bearing of the object does not occur.

 If the source of the acoustic field is outside the decision domain (direction-finding characteristic), an active search is performed (scanning or tracking) by introducing controlled time delays as follows (see Fig. 2). For clarity, consider the timing diagrams (see Fig. 9), illustrating the operation of the delay line circuit and the control unit for them (Fig. 8, in one plane; the work in the perpendicular is identical). The circuit operates in scanning and tracking modes.

 The mode is selected by the level of the FLW signal: a low level corresponds to the scanning mode, and a high tracking mode. In tracking mode, the direction of rotation of the radiation pattern is set by the signal RU (from reverse).

In FIG. Figure 9 shows the change in the main signals in scan mode. First, the delay line is included in channel 1, the delay in which varies linearly over time T ₁ from 0 to τ _max . In this case, the direction signal DRT is low. The maximum delay τ _max corresponds to a rotation of the diagram by an angle θ _ck / 2, after which the beam is rotated back, the delay line is switched to channel 11 and the chart is rotated first to the right by θ _ck / 2, and then back. The rotation time T _{2 is} also equal to T ₁ . The DRT signal strength indicates which channel the delay line is on. Thus, the scanning period T _cc is 4T ₁ . In the proposed direction finder, based on the width of the main maximum of the beam pattern and integration time τ and _{А of the} integrator 32 (see Fig. 7), equal to τ and _А = 140 ms, taking into account the discreteness of the change of the rotation angles Δ θ 1.5 ^о for the scanning range θ _ck + -60 ^about T _ck 22.5 s.

When implementing the delay lines in the form of a shift register 34 (see Fig. 8), the delay value is changed discretely by switching the outputs of the register. The scanning or tracking mode is generated at the output of the circuit 37 (see Fig. 8) by the address code N _a arriving at the multiplexer (MS3) 35 (see Fig. 8). The width of the address code N _a determines the discreteness of the change in the rotation angles Δ θ of the radiation pattern: Δ θ θ _ck / 2N _{A + 1} . In tracking mode, turning accuracy is doubled by increasing Na.

 The main characteristics of the delay line circuit and their control unit are determined based on the required accuracy of scanning and tracking, as well as on the basis of the necessary accuracy of processing the received signal.

sin

(4) для d_g 1 м, θ_ск 120^о, с 330 м/с, τ_м 2,62 мс.Given that the delay time is defined as
τ _m

sin

(4) for d _g 1 m, θ _ck 120 ^о , s 330 m / s, τ _m 2.62 ms.

Let the clock frequency f _{o of} recording and shifting be chosen so that we get ten samples of the signal for the period of the frequency F _{o of the} carrier of the received signal. Then f _o 20 kHz for F _o 2 kHz and to ensure a delay of τ _m it is necessary No. of bits of the shift register N _o 52,4 (N _o f _o ˙ τ _m ). Obviously, it is advisable to round N _o to the nearest number equal to 2 ⁿ , that is, N _o 64. Therefore, it is possible to use a 64-bit shift register, while the clock frequency is f _o N / τ _m 64 / (2.62 ˙ 10 ^-3 ) 24.4 kHz. Then 12.2 samples are provided for the period, and the value of f _o allows you to implement the circuit on the IS series 564.

If the select discrete rotation Δ θ equal to ^about 1.5 diagrams in the scanning mode and ^about 0.75 in the tracking mode, the bit width N _a should be equal to the 5-and 6-i, respectively.

In FIG. 10 is an electrical schematic diagram of the delay lines and their control unit with a clock frequency of 24.4 kHz. The main characteristics of the circuit are f _o 24.4 kHz, θ _ck ± 60 ^o , Δ θ 1.5 ^o / 0.75 ^o , τ _m = 2.62 ms, N _o 64. The shift registers 564IR6 (DD1 DD8) operating in the sequential input mode. The delay switching is performed by 8 ˙ 1 multiplexers (IS 564KP2, DD9 DD12). Multiplexers have a third output state, which made it possible to combine their outputs according to the "wire-OR" scheme. All multiplexers are controlled by the three least significant bits of the address (A ₀ , A ₁ , A ₂ ), and the choice of a particular section of the delay line by signals U ₁ U ₄ .

Addresses Ai are changed with the scanning frequency F _ck , which is obtained by dividing the clock frequency f _{o of the} counter 564IE16 (DD13), the division coefficients of which can be selected by any setting from 2 ¹ to 2 ¹⁴ (except 4 and 8) by setting the jumper.

On the counter 564IE11 (DD14) and trigger 564ТМ2 (DD22.1), the address generation circuit A ₀ A _{4 is} constructed. Counters DD15 and DD16 (564IE11) generate the control signals DRT and DI1. All counters in the circuit operate in reverse mode, controlled by the “+/-” input by TRN and RN signals. The two most significant bits of the address code are used to select a working multiplexer through a 564ID1 (DD18) decoder with 564LN2 (DD19.1-4) inverters.

The counting direction signal TRN is obtained by binary summing of the DRT and RN signals on element 564LP2 (DD20.2). When switching to the tracking mode, the number of discrete radiation pattern positions doubles. This is achieved by switching the changing bits of the address. In scan mode, the least significant bit of address A ₀ is zero, and during tracking it is determined by the state of the least significant bit of counter DD14. Switching is performed by the element DD21.1 (564LA7) with the subsequent inversion of DD21.2. The source of the clock pulses is a generator built on DD19.5,6 inverters. On element DD21.3 made node reset circuit and the beginning of normal operation when you turn on the power source. Element 2I-NOT (DD21.4) is used as a generator of the potential of a logical unit. Switching the input signals for the delay line, as well as switching the signals to the output circuits in accordance with FIG. 9 is performed by a selector-multiplexer 564LS2 (DD17).

 Experimental studies of the proposed acoustic radiation direction finder showed that, compared to a device of a similar purpose, the claimed acoustic radiation direction finder provides scanning of a moving object in two measurement planes (horizontal and vertical) and signal selection against the background of narrow-band localized mobile noise.

Claims (1)

 DIRECTOR OF SOURCES OF ACOUSTIC RADIATION, comprising signal receivers, each of which is connected in series with a bandpass filter, a discrete functional converter, a discrete signal converter connected through an analog signal converter and a first threshold functional signal converter with a matching circuit, having a parallel connection of bandpass filters through an energy channel with second threshold functional signal converter with a matching circuit, characterized the fact that delay lines and a control unit for them are introduced into it, as well as a relative bandwidth selector that is connected in parallel to the circuit with the energy channel, as well as an intermediate and output key for issuing additional information about the bearing angle, and the inputs of the delay lines are connected to the outputs of the discrete functional converters of the sign processing unit and the delay lines, and the outputs of the delay lines are connected to a discrete signal converter, the delay line control unit is connected to the delay lines and with an intermediate key of the block for detecting and selecting interference, the selector of the moving localized interference is connected to the bandpass filters in parallel with the energy channel, the outputs of the energy channel and the selector of the moving localized interference being connected to the matching circuit of the block for detecting and selecting interference, and the coincidence output is connected via the intermediate key to the output key .

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