Acoustic parametric receiver |
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IPC classes for russian patent Acoustic parametric receiver (RU 2445642):
                
 Method of determining bearing of noisy object / 2444747
Method involves receiving an acoustic signal during "electric" rotation of the beam pattern of components x and y of a composite receiver consisting of a vector receiver and a hydrophone. The received signal undergoes analogue-to-digital conversion via Hilbert or Fourier transform with subsequent conversion of the signal into analytical form. Further, the ratio of the imaginary part of the signal to the real part is calculated and that ratio is used to estimate the phase difference between acoustic pressure p(t) and orthogonal components of particle velocity
 Apparatus and method for determining direction of audio source by diver / 2439602
Signal from a source is received at two nondirectional antennae at a distance of λ/4 from each other. The signal from the first antenna is transmitted to the input of an automatic gain control (AGC) amplifier and the signal from the other antenna is delayed by a quarter-period is summed up with the signal from the first antenna. The summation results in formation of a cardioid-type beam pattern. The resultant signal is transmitted to the control input of the AGC amplifier, the gain of which is inversely proportional to the control signal level. As a result, a signal reaches the headphones of the diver, said signal becoming maximum if the diver turns such that the line connecting the right and left side antennae turns in the direction of the source.
 Apparatus for detecting composite broad-band frequency-modulated signals with filtration in scale-time domain based on discrete wavelet transform / 2439601
Apparatus has an analogue-to-digital converter (1) whose output is connected to the input of a recirculator (2). The output of the recirculator is connected to the first input of a discrete wavelet transform computer (3). The wavelet transform output is connected to the input of a fast Fourier transform computer (8), the output of which is connected to the first input of a complex multiplier (9), the output of which is connected to the input of an inverse fast Fourier transform computer (11), the output of which is connected to the input of a squared absolute value computer (12), the output of which is connected to the input of a threshold device (13), the output of which is the output of the apparatus; a control device (14), the outputs of which are connected to control inputs of the analogue-to-digital converter (1), the recirculator (2), the discrete wavelet transform computer (3), a multiplier (5), an inverse discrete wavelet transform computer (7), the fast Fourier transform computer (8), the complex multiplier (9), the inverse fast Fourier transform computer (11) and read-only memory (4, 6, 10).
 System for determining coordinates of underwater objects / 2437114
Coordinate system is created from GIB buoys with base length of 1-3 km, which receives ping signals of underwater objects, synchronised with GPS clocks and time-spaced. Through correlation reception, the GIB buoys determine lag time from each object and relay these data to a control station. Based on the lag time and data on hydrostatic pressure on the underwater object, the control station calculates coordinates and displays the position of each object.
 Device to compensate for wave front curvature / 2431153
Proposed device represents adaptive system to allow optimising antenna phase reception of acoustic signals in Fresnel range. For this, proposed device comprises multi-component cylindrical antenna with N receiving channels. It differs from known designs in that it incorporates additionally HF signal generator and HF radiator and allows every preamplifier to switch over to frequency multiplexer mode. Said distinctive features allow heterodyning received useful HF signal and optimising antenna phase reception of acoustic signals with curved wavefront.
 Method of determining heading angle to radiation source from mobile subsurface object and device for realising said method / 2402785
Method involves generation and emission from a source of a harmonic signal with frequency ω, reception of an acoustic signal using a set of N≥8 hydrophones which form a circular measuring base directed into the horizontal plane, picking up quadrature components of the complex envelope of received acoustic signals, measurement of the phase of acoustic signals, preliminary phasing of the measuring base into N directions passing through the centre of the measuring base and each of the N hydrophones, determination of the direction which corresponds to the maximum of the signal and a hydrophone lying in that direction, calculation of the heading angle to the source in a local coordinate system associated with the measuring base using corresponding formulas. The hydrophone lying in the direction of the signal maximum is taken as the first hydrophone. The mobile subsurface object is also fitted with a pair of hydrophones spaced out in a diametrical plane along the mobile subsurface object at a distance of 1≤λ/4σθ. After calculating the bearing, the heading angle β0 to the source is calculated using formula β0=β1±θ0, σβ0=σβ, where β1 is the heading angle of the first hydrophone of the circular measuring base, the sign (+) is taken for the heading angle of the starboard side, the sign (-) is taken for the heading angle of the port side, σβ0 is the error in determining the heading angle, σθ is the bearing measurement error. The mobile subsurface object then synthesises a beam path on which the condition β0=180°+σθ is satisified, and a traversing path on which the condition β0=±90°+σθ is satisfied. Further, phase difference of acoustic signals Fm received using an extra pair of hydrophones is measured on the traversing path at time moments tm, m=1-M. The values of phase difference of acoustic signals Fm(tm) measured on the acoustic path are approximated with a linear function F=a(t-t0). Parametres a are determined through a least-squares method using corresponding formulas, and the true heading angle to the source at point t=t0 is determined using formula
 Device for detection of narrow-band noise hydroacoustic signals based on calculation of integral wavelet-spectrum / 2367970
Invention is related to the field of hydroacoustics, namely to devices for detection of narrow-band noise hydroacoustic signals (with spectral density of power in the form of separate discrete components or their scales) at the background of additive noise. Invention is based on calculation of continuous wavelet transformation of input process on the basis of complex analytical wavelet, relative band of amplitude spectrum of which matches relative band of spectral density of detected signal power. Device comprises analog-digital converter (ADC) 1, recirculator 2, the first calculator of fast Fourier transform (FFT) 3, complex multipliers 4.1 - 4.M, scaling devices 5.1 - 5.M, device of complex conjugation 6, device of negative frequencies nulling 7, the second calculator FFT 8, permanent memory (PM) 9, calculators of reverse FFT 10.1 - 10.M, calculator of module square 11, averaging device 12, threshold device 13, control device 14.
 Method for protection of water barriers / 2364883
Invention is related to hydroacoustics and may be used for protection of objects from the barrier side in water medium. According to method, signal is generated from hydroacoustic antenna arranged in the form of piezoelectric cable sections, ends of which are connected to radio frequency cable with the help of matching devices fed from common source, signal voltage is picked up from loading resistor and is sent through separating capacitor to inlet of alarm signal generator, object parametres are identified by results of analysis of spectral and time variation of signal.
 Method and system of determining trajectory of supersonic projectile / 2358275
Present invention can be used for determining the trajectory of a supersonic projectile. At least the initial part of signals is measured, containing information only on impact wave, using five or more acoustic sensors, spread out in space such that they form an antenna. From this measured initial part of signals, the difference in arrival time for a pair of sensors is determined. A genetic algorithm is applied to the initial chromosome, which contains initial estimated parameters of the projectile trajectory. For a given number of generations, projection errors are calculated for solutions, obtained from chromosomes from the genetic algorithm. The ratio of solution with the least values of projection errors to the ambiguous solution is calculated, and if this ratio is greater than a given value, the solution with the least value of calculated projection error is chosen as the correct trajectory of the projectile.
 Method to receive information on sound-producing objects in sea / 2353946
Noise signals are received in horizontal and vertical plane, frequency-time processing is carried out in every spatial channel of observation, output voltages of formed space channels are squared and summed in all frequency samples, then averaged in time, signals are centered and normalized to noise, signal energy and information parameters are accompanied, route detection is carried out by comparison of generalised weight of signal local maximums with threshold of signal detection, which corresponds to threshold ratio of signal-noise. Method is based on the fact that in every cycle of viewing noise signals are received, primarily processed, squared, secondarily processed and route-detected in at least another two frequency ranges and additionally, at least, for two angles of observation in vertical plane, creating new expanded set of space channels.
Method of determining bearing of noisy object / 2444747
Method involves receiving an acoustic signal during "electric" rotation of the beam pattern of components x and y of a composite receiver consisting of a vector receiver and a hydrophone. The received signal undergoes analogue-to-digital conversion via Hilbert or Fourier transform with subsequent conversion of the signal into analytical form. Further, the ratio of the imaginary part of the signal to the real part is calculated and that ratio is used to estimate the phase difference between acoustic pressure p(t) and orthogonal components of particle velocity
 Hydro acoustic measurement hardware complex carrier / 2424151
Invention relates to hydro acoustics and may be used for hydro acoustic analysis of noise radiation in natural water reservoir. Proposed hardware complex carrier comprises buoy made up of elongated torpedo-like hull with acoustically permeable fairing with hydrophone arranged at its center, while positive buoyancy chambers are arranged at bow and stern parts. Said buoy houses components for preliminary conversion of signals. note here that hydrophone output is connected via said components to processing equipment arranged outside said buoy. Depth transducer is arranged outside said buoy. Relation between horizontal and vertical axes of torpedo-like buoy makes not less that five. Angle between beams from hydrophone sensitive element to edges of positive buoyancy chambers makes at least 140°.
 Method and device for continuous visualisation by system of ultrasonic converter / 2404711
Invention relates to medical equipment, and particularly device and method of ultrasonic visualisation. Device comprises low-profile converter and remote system of ultrasonic visualisation. Converter comprises wide-aperture grid matrix, including gasket made of material with low acoustic losses and wider than visualisation aperture. System of ultrasonic visualisation comprises a control panel. Method of continuous ultrasonic visualisation consists in the fact that gasket is fixed on patient above examined object enclosed by a barrier for production of images. Scanning lines are generated by means of grid matrix. Control panel is used to control image tuning and to position scanning lines generated grid matrix. Barrier from image is removed by re-positioning of sector scanograms with the help of control panel without manual displacement of converter.
 Acoustic radar / 2374665
Invention may be used for determination of removal of acoustic source (AS) using acoustic radar (AR), its bearing and topographic coordinates (TC) of this acoustic source. Acoustic radar includes two linear patterns (LP) including twenty sonic detectors (SD) each, three signal processing paths (SPP), computing machine, chain of generation of selection pulse (CGSP) and chain of generation of blocking pulse (CGBP). Each signal processing path consists of signal extractor, voltage adder (VA), special amplitude detector, analog-to-digital converter (ADC) and register connected to it in series which is connected to computing machine. Signal extractor consists of twenty selective amplifiers, twenty coincidence circuits and twenty electronic switches. Chain of generation of selection pulse includes in-series connected front sonic detector, Schmitt trigger and univibrator. Chain of generation of blocking pulse includes in-series connected rear sonic detector, Schmitt trigger and univibrator. Also control system of directional characteristic is added which consists of two micro-converters, resistance-capacitance (RC) differentiator and diode, this system allows to connect outputs of selective amplifiers with inputs of voltage adder determined by program at a given time.
 Method for detection, identification and determination of space coordinates of objects at surfacing of underwater vehicle / 2308052
Long-range detection, identification and determination of space coordinates of objects, as well as of the parameters of sea disturbance are accomplished according to the information contained in the acoustic high-frequency pumping waves radiated from the underwater vehicle and dispersed on the surface bubble layer, in the acoustic low-frequency waves formed in the process of motion of the objects, as well as in the high-frequency combination waves formed in a heterogeneous sea medium due to a non-linear interaction of the hydro-acoustic high-frequency pumping waves and the low-frequency acoustic waves.
 Mode of forming of a frequency independent characteristic of a direction with a working sector of a multi-element underwater acoustic receiving circuolar antenna / 2293449
The mode includes reception of acoustic signal, its transformation by each element into electric signal, amplification of electric signals from each element of the sector with definite weighting coefficients and summing up of intensified electric signals from all elements of the sector. At that the intensified signals from each element of the sector are delayed on definite time.
 Method and device for measuring radio location reflectivity and doppler shift by means of radar / 2249230
Invention can be used in meteorological radars, 360 degree survey radiolocation stations as well as for remote sounding and sonar systems. During process of measuring of characteristics by radar of sonar the pulses are transmitted and signal is received between transmission of pulses, which signal depends on transmitted pulses and on distribution of characteristics of target at different ranges. Transmitted pulses form cyclically repeated code or continuously changing sequence of pulses. Distribution of characteristics is determined by means of representing the pulses in form of set of linear equations where variables have to be values of characteristics measured at required distances. The set of equations should be subsequently solved. As a result the conflict between measurement of power and Doppler shift is eliminated.
Method and device for measuring radio location reflectivity and doppler shift by means of radar / 2249230
Invention can be used in meteorological radars, 360 degree survey radiolocation stations as well as for remote sounding and sonar systems. During process of measuring of characteristics by radar of sonar the pulses are transmitted and signal is received between transmission of pulses, which signal depends on transmitted pulses and on distribution of characteristics of target at different ranges. Transmitted pulses form cyclically repeated code or continuously changing sequence of pulses. Distribution of characteristics is determined by means of representing the pulses in form of set of linear equations where variables have to be values of characteristics measured at required distances. The set of equations should be subsequently solved. As a result the conflict between measurement of power and Doppler shift is eliminated.
Mode of forming of a frequency independent characteristic of a direction with a working sector of a multi-element underwater acoustic receiving circuolar antenna / 2293449
The mode includes reception of acoustic signal, its transformation by each element into electric signal, amplification of electric signals from each element of the sector with definite weighting coefficients and summing up of intensified electric signals from all elements of the sector. At that the intensified signals from each element of the sector are delayed on definite time.
Method for detection, identification and determination of space coordinates of objects at surfacing of underwater vehicle / 2308052
Long-range detection, identification and determination of space coordinates of objects, as well as of the parameters of sea disturbance are accomplished according to the information contained in the acoustic high-frequency pumping waves radiated from the underwater vehicle and dispersed on the surface bubble layer, in the acoustic low-frequency waves formed in the process of motion of the objects, as well as in the high-frequency combination waves formed in a heterogeneous sea medium due to a non-linear interaction of the hydro-acoustic high-frequency pumping waves and the low-frequency acoustic waves.
Acoustic radar / 2374665
Invention may be used for determination of removal of acoustic source (AS) using acoustic radar (AR), its bearing and topographic coordinates (TC) of this acoustic source. Acoustic radar includes two linear patterns (LP) including twenty sonic detectors (SD) each, three signal processing paths (SPP), computing machine, chain of generation of selection pulse (CGSP) and chain of generation of blocking pulse (CGBP). Each signal processing path consists of signal extractor, voltage adder (VA), special amplitude detector, analog-to-digital converter (ADC) and register connected to it in series which is connected to computing machine. Signal extractor consists of twenty selective amplifiers, twenty coincidence circuits and twenty electronic switches. Chain of generation of selection pulse includes in-series connected front sonic detector, Schmitt trigger and univibrator. Chain of generation of blocking pulse includes in-series connected rear sonic detector, Schmitt trigger and univibrator. Also control system of directional characteristic is added which consists of two micro-converters, resistance-capacitance (RC) differentiator and diode, this system allows to connect outputs of selective amplifiers with inputs of voltage adder determined by program at a given time.
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FIELD: physics. SUBSTANCE: acoustic parametric receiver has a high-frequency voltage generator 1 connected to an acoustic transducer 2, which is in acoustic contact through an acoustic waveguide 3, the boundaries of which are transparent for a low-frequency acoustic signal and not transparent for a high-frequency acoustic signal, with a wideband acoustic transducer 4, connected through series-connected selective amplifier 5, phase changer 6, phase detector 7, attenuator 8, with a recorder 9. The second input of the phase detector 7 is connected to the output of the high-frequency voltage generator 1. The broadband acoustic transducer 4 is connected through series-connected resonance amplifier 10 and amplitude detector 11, to the control input of the selective amplifier 5. The output of the phase detector 7 is connected through an integrator 12 to the control input of the phase changer 6. Outputs of the control unit 13 are connected to the control inputs of the high-frequency voltage generator 1, the resonance amplifier 10, the attenuator 8, the recorder 9 and the second control input of the selective amplifier 5. EFFECT: broader functional capabilities of the device. 3 dwg
The invention is intended for directional reception of acoustic signals in different environments and can be used in underwater acoustics, when the location registration of the noise, as well as in all fields of science and technology related to the need for directional reception of acoustic signals. A device for parametric receiving acoustic signals using the effect of interaction received low-frequency signal from the auxiliary high-frequency acoustic signal [1] and contains a generator of high frequency electrical voltage connected to the acoustic transducer in acoustic contact with the second acoustic transducer is connected through serially connected selective amplifier and narrowband filter with the Registrar. High-frequency voltage from the generator is fed to the acoustic transducer radiating into the environment auxiliary high-frequency acoustic signal, which is distributed in the environment and is the second acoustic transducer. The electrical signal from the transducer is connected in series through a selective amplifier and narrowband filter is supplied to the logger. During propagation environment, the received low-frequency acoustic signal at the same time the auxiliary high-frequency, is their interaction and the emergence of additional harmonic components in the spectrum of the high frequency signal with a frequency different to the sum and difference frequencies of high-frequency and low-frequency signals. This complex signal from the second acoustic transducer is amplified in a selective amplifier, and lateral components with the sum or difference frequencies carrying the information about the received low-frequency signal are allocated narrowband filter and served on the Registrar. The reasons that impede the achievement of the technical result is the limited operational capabilities are attributable to the following. The amplitude of the lateral components is significantly smaller than the amplitude of the main RF signal, therefore filtering associated with considerable difficulties: At high q-factor of the filter circuit significantly increases the duration of transient processes; filters should have a significant Squareness to effectively suppress the main high-frequency signal. All paths of the receiver must have a linear amplitude characteristics for small signals from the sum and difference frequencies, and for the basic high-frequency signal in the environment interaction (changing the attenuation factor, the parameter of nonlinearity of the medium), to which that affects the overall sensitivity of parametric receiver. To change the direction of receiving low frequency acoustic signal, it is necessary to mechanically move in the environment of the acoustic transducers. The signs consistent with the declared facility: generator of high frequency electrical voltage connected to the acoustic transducer in acoustic contact with the second acoustic transducer is connected to a selective amplifier, a recorder. From a number of data deficiencies freely device for parametric receiving acoustic signals [2], in which for more information on the received acoustic signal using all frequency components of the auxiliary high-frequency signal, not only the lateral components with the sum or difference frequencies, and comprising a generator of high frequency electrical voltage connected to the acoustic transducer in acoustic contact through a medium with the second acoustic transducer is connected through serially connected selective amplifier and a phase detector with the Registrar; the second input of the phase detector is connected to the output of the generator high-frequency electric voltage. This device also uses the effect of interaction received low-frequency signal with auxiliary is a high frequency acoustic signal. High-frequency voltage from the generator is fed to the acoustic transducer radiating into the environment auxiliary high-frequency acoustic signal, which is distributed in the environment and is the second acoustic transducer. The electrical signal from the transducer through a selective amplifier is fed to one input of a phase detector, a second input connected to a generator of high frequency electrical voltage, and the output of the phase detector is connected to the logger. If low-frequency acoustic signal is propagated in the same area of the environment, where the auxiliary high frequency, the result of their interaction is the phase modulation of a high frequency signal of the low-frequency [3]. As a result, the output of the phase detector is obtained voltage containing information about the received low frequency signal. The reasons that impede the achievement of the technical result is the limited operational capabilities are attributable to the following. The use of phase detection for highlighting information about the received signal leads to stringent requirements on the stability of the frequency-phase characteristics of all nodes parametric receiver. The amplitude characteristic of the phase detector of them is no periodic dependence on the phase difference signal, arriving at its inputs [4, S. 168], as well as in this parametric receiver initial phase detected signals have arbitrary values, then disrupted functional connectivity between the received low-frequency acoustic signal and the output signal of the phase detector. The signal level at the output of the phase detector depends on the levels of the signals at its inputs. The signal coming from the output of the generator high-frequency electric voltage to one of the inputs of the phase detector has a constant amplitude, and the signal level received at a second input of the phase detector with the election of the amplifier depends on many factors (the mutual orientation of acoustic transducers, the value of the coefficient of attenuation of high-frequency acoustic signal in the environment and others). To change the direction of receiving low frequency acoustic signal, it is necessary to mechanically move in the environment of the acoustic transducers. From a number of the above-mentioned shortcomings of the free "parametric Acoustic receiver" [5]with the greatest number of matching signs with the inventive device. It contains: a generator of high frequency electrical voltage connected to the acoustic transducer in acoustic contact with a broadband acoustic Converter is the motor, connected through serially connected electoral phase shifter and a phase detector with a measuring device; a second input of the phase detector is connected to the output of the generator high-frequency electric voltage, broadband acoustic transducer is connected through serially connected resonant amplifier and peak detector with the control input of the selective amplifier, and the output of the phase detector via the integrator is connected with the control input of the phase shifter. The generator produces an electrical high-frequency voltage supplied to the acoustic transducer and one of the inputs of the phase detector. The acoustic signal emitted by the transducer in the environment and is a broadband acoustic transducer. Under the influence of an external acoustic signal, and the nonlinearity of the medium parameters of the signal receiving transducer will have a complex spectrum consisting of a high frequency signal with side frequency components and high frequency harmonics of the signal. Moreover, the ratio of the amplitudes of the harmonics will depend on the values of the parameters of the nonlinearity of the medium. Harmonic high-frequency signal amplified by the resonance amplifier and the detected amplitude detector is ohms; the voltage from its output to change the gear ratio of the electoral amplifier so that the gain decreases with the increase of the nonlinear characteristics of the environment. The voltage output from the selective amplifier through an adjustable phase shifter is fed to the second input of the phase detector. Constant voltage component at the output of the phase detector is close to zero in the case, if the working point is at the center of the linear plot its amplitude characteristics. This DC component is extracted by the integrator and controls the phase shifter so that the phase detector worked on a linear plot its amplitude characteristics. Thus, the voltage at the output of the phase detector will be definitely be characterized accept low-frequency acoustic signal and not will depend on the changing characteristics of the environment, i.e. the receiver will have a constant sensitivity. The reasons that impede the achievement of the technical result is the limited operational capabilities, due to the fact that for changing the direction of receiving low frequency acoustic signal, it is necessary to mechanically move in the environment of acoustic transducers, it is impossible to carry out the electrical scanning direction of receiving low frequency acoustic the sky signal. The aim of the present invention is the enhanced operational capabilities parametric receiver. This goal is achieved by the fact that in the parametric acoustic receiver containing a Registrar, a generator of high frequency electrical voltage connected to the acoustic transducer in acoustic contact with the broadband acoustic transducer is connected through serially connected selective amplifier and a phase shifter with a phase detector; a second input of the phase detector is connected to the output of the generator high-frequency electric voltage, broadband acoustic transducer is connected through serially connected resonant amplifier and peak detector with the control input of the selective amplifier, and the output of the phase detector via the integrator is connected with the control input of the phase shifter, inputs of the attenuator is located between the output of the phase detector and the Registrar, and also the control unit, the output of which is connected to control inputs of the generator high-frequency electric voltage, the resonant amplifier, attenuator, the Registrar and with the second Manager of the entrance electoral amp; between the acoustic transducer and broadband acoustic PR what education is an acoustic waveguide, the borders of which are transparent to low-frequency acoustic signal and is opaque to high-frequency acoustic signal. The invention is illustrated by drawings. Figure 1 shows the functional diagram of the device, and figure 2 - diagram of the acoustic channel parametric receiver figure 3 - results of calculation of the directional diagrams parametric acoustic receiver. Acoustic parametric receiver comprises a generator of high-frequency electric voltage 1 is connected to the acoustic transducer 2, which is in acoustic contact through the acoustic waveguide 3, the boundaries of which are transparent to low-frequency acoustic signal and is opaque to high-frequency acoustic signal with a broadband acoustic transducer 4 is connected through serially connected electoral amplifier 5, the phase shifter 6, a phase detector 7, the attenuator 8 9 Registrar; second input of the phase detector 7 is connected to the generator output frequency voltage 1, a broadband acoustic transducer 4 is connected through serially connected resonant amplifier 10 and the amplitude detector 11 with the control input of the selective amplifier 5 and the output of the phase detector 7 through the integrator 12 is connected with the control input is m the phase shifter 6, the outputs of the control unit 13 is connected to control inputs of the generator high-frequency electric voltage 1, the resonance amplifier 10, the attenuator 8, 9 Registrar and with the second Manager of the entrance electoral amplifier 5. High-frequency voltage output from the generator 1 is supplied to one input of phase detector 7, and the acoustic transducer 2, a radiating acoustic waveguide 3 high-frequency acoustic signal. The boundaries of the waveguide is transparent to low-frequency acoustic signal and is opaque to high-frequency acoustic signal. The parameters of the waveguide 3 is chosen such that the velocity of propagation of high frequency acoustic signal in it depended on the frequency (see, for example, [6]). At the same time in the waveguide extends low-frequency acoustic signal, which must be taken. While propagation in the waveguide material is high-frequency and low-frequency acoustic signals is their interaction, in which the high frequency signal is modulated by the phase of low frequency. This modulated phase high frequency signal and its higher harmonics are accepted broadband acoustic transducer 4, the signal of which is fed to the input of the electoral amplifier 5, is held to the frequency of the high frequency signal and to the input of the resonant amplifier 10, configured on the frequency of one of the harmonics (e.g. two) of the high-frequency signal. The harmonics of the high-frequency signal, provided that the high-frequency signal is constant, depends on the value of the parameter of nonlinearity of the medium of the waveguide. The output signal of the resonant amplifier 10 is detected by the amplitude detector 11, is fed to the control input of the electoral amplifier 5 and changes its gain (the higher the level of the control signal, the less gain). This eliminates errors caused by changes in the value of the nonlinearity coefficient of the waveguide material. With exit polling amplifier 5 through the phase shifter 6, the signal at the second input of the phase detector 7, and with its release proyektirovanii signal corresponding to the received low-frequency signal through the attenuator 8 is input to the Registrar 9. The output of the phase detector 7 through the integrator 12 is connected with the control input of the phase shifter 6. Constant voltage component at the output of the phase detector 7 is close to zero in the case if the working point of the detector is located in the centre of the linear plot its amplitude characteristics. This DC component is extracted by integrator 12 and controls the phase shifter 6 to the phase detector worked on linear teaching is TKE its amplitude characteristics. This eliminates the error caused by changes in the characteristics of the material of the waveguide, and the phase instabilities blocks parametric receiver, i.e. the receiver will have a constant sensitivity. For scanning in the space of beam parametric receiver from the output of the control unit 13 of the control signals on the control input of the generator high-frequency electric voltage 1 and change the frequency of the generated electric voltage at a control input of the resonant amplifier 10 and change the frequency settings of the amplifier so that it was equal to the frequency of one of the harmonics of the high frequency signal on the control input of the attenuator 8 and changing the gear ratio in such a way as to compensate for errors caused by changes in the slope of the amplitude characteristics of the phase detector and changes the attenuation of the signal in the waveguide material to change its frequency at the control input of the electoral amplifier 5 and changing the frequency of the amplifier is set so that it was equal to the frequency of a high frequency signal, and the control input of the Registrar 9, transmitting information on the position in space of the maximum beam parametric receiver. Acoustic tra is t the simplest admissions parametric antenna includes a radiating and receiving transducers, located at a distance L from each other, as shown in figure 2. The directivity of the antenna depends on the ratio of the distance L to the wavelength of the low frequency signal is Λ, and for directional reception, you must have L/Λ>>1. If you accept a low-frequency plane acoustic wave propagating at an angle θ to the x-axis, the change in the propagation velocity of the auxiliary high-frequency acoustic waves due to the nonlinearity of the medium can be defined as:
where where R0Ωthe amplitude of the sound pressure of the low-frequency wave signal [7, 8]. Calculating the increment of the speed of sound [7, 8] and the projection of the vibrational velocity of the particles in the low-frequency wave on the x axis
and secondary sources
where
where This expression shows that the directivity of the reception parametric antenna when distributing pump waves in free space in the environment without dispersion represents the directional characteristics of the antennas traveling wave. Thus the maximum directivity is obtained when θ=0. It is physically explainable by the fact that the maximum of wave interaction is obtained by collinear propagation of waves with equal speeds. If the auxiliary high-frequency acoustic wave pumping is distributed in all zvakapressa.com for the waves of low frequency signal waveguide, the phase velocity of the waves pumping may change when the frequency of the pump wave due to geometric dispersion. On the antenna aperture field will be similar field traveling wave will be created and the phase distribution of the sources, resulting from the nonlinear interaction, the length of the antenna, changing when you change the frequency of the pump wave. Let the field at the aperture of the antenna is described by the formula a(x,t)=Aei(ωt-α(x)), where ω is the angular frequency, amplitude And constant, but the phase is distributed linearly α(x)=βx, where The phase velocity of the pump waves in a circular waveguide is greater than the speed of sound in a dispersionless medium, and receiving the maximum with the direction corresponding to the angle θ to the x axis To obtain a directional characteristic of the antenna is possible by integrating field generated by sources with the same phase distribution. The result will be
Since the phase velocity in a circular waveguide can vary from the speed of sound in a dispersionless medium to infinity, we will analyze changes the directivity of the reception parametric antenna when changing the phase velocity of the pump wave. In this case, given that the focus is mainly determined by the integral in the expression (2), shall determine the characteristic is napravlennosti
Figure 3 shows the directivity in the plane passing through the axis of the antenna and perpendicular to the surface of the antenna pumping. Shows the directivity for L/Λ=10, p0=1500 m/s, νf=1500 m/s (curve 1), 2000 m/s (curve 2), 5000 m/s (curve 3), 10000 m/s (curve 4). The analysis shows that when increasing the phase velocity of the pump wave directional turns and becomes a "funnel". When νf→0the cone is pressed against the axis, and when νf=C0the maximum sensitivity in the direction of the axis. Thus, in the proposed parametric receiver scans the maximum beam parametric receiver electrical path due to a change in frequency of the auxiliary high-frequency acoustic signal that extends the capabilities of the receiver. Sources of information 1. Tdimon "Nonlinear acoustics and its role in Geophysics marine sediments", Ed. Hapton, M., Mir, 1977, s-242. 2. US patent # US 3662444, IPC G01S 9/66, 1975. 3. Zverev V.A. and Kalachev A.I. Modulation sound sound at the intersection of the acoustic waves. "Acoustic magazine, 1970, No. 2, s-251. 4. A particularly E.A., jurkovich K., Sodl J. "Application of analog circuits"), is Pleased is about and a link, 1990. - 320 S. 5. Patent SU 702852 "parametric Acoustic receiver", IPC G01S 3/80, epubl. 6. Rgic "fundamentals of hydro-acoustics", Leningrad, Sudostroenie, 1978, p.101-106. 7. Vasakronan, V.P. Kuznetsov, Bgordon, Spearazon, Whitebalance. Nonlinear and parametric processes in ocean acoustics. - Rostedt. Rostov-on-don. 2007. - 448 S. 8. Vasakronan, Spearazon, Whitebalance. Hydroacoustic parametric system. - Rostov-on-don: Rostedt. 2004. - 400 C. 9. Patent RU 2096808 "Method for detection of low-frequency acoustic radiation", IPC G01S 15/04, publ. 20.11.1997. 10. Patent RU 2158029 "Method of reception of elastic waves in sea water (options)", IPC G10K 11/00, G10K 15/02, publ. 20.10.2000. Acoustic parametric receiver containing a Registrar, a generator of high frequency electrical voltage connected to the acoustic transducer in acoustic contact with the broadband acoustic transducer is connected through serially connected selective amplifier and a phase shifter with a phase detector; a second input of the phase detector is connected to the output of the generator high-frequency electric voltage, broadband acoustic transducer is connected through serially connected resonant amplifier and peak detector with a control input izbirat is a high power amplifier, and the output of the phase detector via the integrator is connected with the control input of the phase shifter, inputs of the attenuator is located between the output of the phase detector and the Registrar, and the control unit, the output of which is connected to control inputs of the generator high-frequency electric voltage, the resonant amplifier, attenuator, the Registrar and with the second Manager of the entrance electoral amp; between the acoustic transducer and the broadband acoustic transducer is an acoustic waveguide, the boundaries of which are transparent to low-frequency acoustic signal and is opaque to high-frequency acoustic signal.
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