RU2101722C1 - Device for estimation of noise level of parametric receiving antenna - Google Patents

Abstract

FIELD: hydroacoustics; measurement of parameters of low-frequency signals by means of parametric receiving antenna. SUBSTANCE: device includes high-frequency pump oscillator 1, power amplifier 2 and radiator 3 connected in series; low-frequency signal generator 4, power amplifier 5 and radiator 6 are also connected in series; receiving element of parametric receiving antenna, signal processing unit 8, spectrum analyzer 9 and selector switch 10. One input of selector switch 10 is connected with output of receiving element of parametric antenna and other input is connected with output of signal processing unit; output of selector switch is connected with input of spectrum analyzer. Device is also provided with low-frequency calibration signal generator 1, power amplifier 12 and radiator 13 which is located in close proximity to receiving element of parametric receiving antenna which is calibrated beforehand for receiving the signals frequencies: ω_pump-pump frequency; ω_pump± Ω-heterodyne frequencies; Ω - low-frequency legitimate signal; Ω-ΔΩ - low-frequency calibration signal. EFFECT: enhanced efficiency. 3 dwg

Description

 The invention relates to hydroacoustic technology and can be used in hydroacoustic means (GAS) for various purposes, incorporating parametric receiving antennas (PAP).

A device for detecting low-frequency (LF) sonar signals, comprising serially connected a master oscillator of a broadband signal, an electro-acoustic transducer acting as a pump emitter, mechanically connected to a receiving hydrophone, which is connected to an electronic processing unit, including a band-pass filter connected to several identical frequency channels consisting of correlators, band-pass filters and devices with adjustable time delay [1]
The disadvantages of this device include the impossibility of determining the levels of self-interference of the PAP directly during its operation, as well as the need for additional special equipment and the time required to calibrate the PAP.

There is also known a device for detecting low-frequency signals, comprising a random sequence generator of high-frequency pulses (HF), a power amplifier and a pump emitter mechanically coupled to a receiving hydrophone, which in turn is connected to a processor including a set of notch filters and a signal comparison unit with time-defined implementations of the emitted pump signal [2]
The disadvantages of this device include the impossibility of determining the levels of self-interference of the PAP directly during its operation, the need for additional special equipment and the time required for calibration in order to determine the level of self-interference of the PAP.

The closest in technical essence to the claimed object relates to a device containing a series-connected pump signal generator, power amplifier and emitter, series-connected low-frequency signal generator, power amplifier and radiator, receiver PAP, signal processing unit and spectrum analyzer [3]
The disadvantages of the prototype device include the impossibility of determining the levels of self-interference of the PAP directly during its operation, the low accuracy of determining the level of self-interference of the PAP.

 The problem that is solved by the invention is to develop a device that is free from the above disadvantages.

 The technical result of the invention is to develop a device that provides high accuracy of measuring the parameters of the low frequency of the useful signal by monitoring the level of the actual interference of the PAS directly during its operation.

 Figure 1 presents the structural diagram of the device.

The device comprises a series-connected RF generator of a pump signal 1, a power amplifier 2 and a radiator 3, series-connected a generator of a low-frequency signal 4, a power amplifier 5 and a radiator 6, a receiving element of the control panel 7, a signal processing unit 8, a spectrum analyzer 9, a switch 10, one the input of which is connected to the output of the receiving element of the PAP, and the other to the output of the signal processing unit, the output of the switch is connected to the input of the spectrum analyzer, the generator of the calibration low-frequency signal 11, the power amplifier is connected in series and 12 and an emitter 13, which is located in close proximity to the receiving element of the PAP, and the receiving element of the PAP is pre-calibrated to receive the signal at frequencies ω _n pump; ω _n ± Ω of Raman frequencies; Ω LF - useful signal, W - ΔΩ LF calibration signal.

 The device operates as follows.

From the output of the RF generator of the pump signal, a continuous RF signal at a frequency w _{n is} supplied to the input of the power amplifier 2 and then fed to the emitter 3, with the help of which the radiation of the RF pump wave occurs. An acoustic pump wave propagates in the direction to the source of the low-frequency useful signal 6. The useful low-frequency signal is formed in turn by the low-frequency signal generator 4, power amplifier 5 and emitter 6. In an aqueous medium, a nonlinear interaction of the high-frequency pump wave occurs at frequency ω _n and LF-waves on the frequency Ω As a result, waves are formed at combination _{of n} frequencies w ± Ω are taken PAP receiving member 7. In the signal processing unit 8 is released LF useful signal from a modulation process by kids ktirovaniya. Next, the LF-useful signal is fed to a spectrum analyzer 9 for registration. At the same time, using the generator of the low-frequency calibration signal 11, the power amplifier 12 and the emitter 13, a low-frequency calibration signal is generated, amplified, and radiated at a frequency of Ω-ΔΩ. transducer, as well as separate monitoring on the screen of the spectrum analyzer.

The signals at frequencies w _n and Ω-ΔΩ can interact with each other due to the nonlinearity of the electro-acoustic transducer used as the receiving antenna of the PAP, as well as the signal processing unit. As a result of the "spurious" interaction, the signals of combination frequencies ω _n ± (Ω-ΔΩ) are formed, which along with the signals ω _n ± Ω (a useful effect for PAP) are received by the receiving element of the PAP. In the processing unit, also (by analogy with the above), the LF calibration signal is extracted by the detection method. On the screen of the spectrum analyzer, discrete components (DS) will be simultaneously recorded at frequencies: Ω useful effect, W-ΔΩ level of the calibration low-frequency signal, which determines the level of “spurious” modulation. The transmitter of the calibration low-frequency signal is located in the immediate vicinity of the receiving element of the PAP (at a distance of ≤1 m), which excludes the "shadowing" of the receiving element of the PAP. In this case, there is practically no region of interaction of acoustic signals in a nonlinear aqueous medium (base PAP ≤1 m). At the same time, the interaction of signals at frequencies w _n and Ω occurs in an extended (hundreds of meters or more) region of the aquatic environment. In the absence of interaction of waves at frequencies Ω and ω _n (incorrectly selected pump signal parameters and other reasons), the amplitudes of the discrete components at frequencies Ω and Ω-ΔΩ can be the same (Fig. 2, a), which indicates that the block is nonlinear signal processing and is identical with the electroacoustic transducer nonlinearity aqueous medium for a given frequency of the pump signal w _n varying pumping signal frequency (e.g., selecting its close to the resonant frequency of sound diffusers: bubbles, the wake guinea q MDL biological objects with gas bubbles, etc.) can be significantly (by 2-3 orders of magnitude and more) increase of nonlinearity aqueous medium. This circumstance will lead to an effective interaction of waves at frequencies ω _n and Ω in a nonlinear extended region of the aquatic environment. In this case (Fig. 2, b) the amplitude of the discrete component at the frequency Ω will significantly exceed the same parameter for the frequency W - ΔΩ Thus, the level of intrinsic interference is monitored directly during the operation of the control panel.

 The accuracy of determining the PAP intrinsic noise level will be determined by the accuracy of reading information from the spectrum analyzer screen about the amplitude of the discrete component at the frequency W - ΔΩ and the level of modulation components that occur when interacting in a nonlinear aqueous medium based on ≤1 m (the distance between the receiving elements of the PAP and the transmitter of the calibration low frequency -signal), which is completely negligible.

 Example. In FIG. Figure 3 shows the omitted part of one of the PPA models developed and manufactured by the author. The receiving element of the antenna is made in the form of a cylinder, along the generatrix of which there are magnetostrictive converters from the GAS MG-10M. The emitter of the HF pump signal is located in the geometric center of the cylinder, and the emitter of the calibration LF signal is located on the rod at a distance of about 1 m from the receiving antenna (receiving element of the PSA). The frequency of the pump signal was 32 kHz, the frequency of the low-frequency useful signal was 1005 Hz, and the frequency of the calibration low-frequency signal was 1015 Hz. In this case, a subband emitter 1 from the instrumentation kit 10 having a wavelength in the vertical plane of 0.6 m was used as the emitter of the calibration low-frequency signal. The cylindrical subband emitter 1 was mounted horizontally on the rod, which virtually eliminated the “shadowing” of the PSA receiving element (in the quality of which in this case was used a cylindrical multi-element antenna).

Comparative analysis with the prototype device shows that the claimed device is characterized by the presence of new features: an additional generator of the low-frequency calibration signal, which is connected in series with the power amplifier and the emitter of the calibration low-frequency signal and switch. In this case, the emitter of the calibration low-frequency signal is located in the immediate vicinity (at a distance of ≤1 m) from the receiving element of the PAP, and the receiving element of the PAP is in turn pre-calibrated to receive signals at frequencies w _n , ω _n ± Ω, Ω and Ω-ΔΩ .
Thus, the claimed device meets the criteria of the invention of "novelty."

 Comparison of the claimed device with other technical solutions shows that these distinguishing features are widely known.

 In hydroacoustics, it is known to use a control emitter to emit signals in order to verify the operability of the HAS receiving path. However, it is not known to use a generator of a calibration low-frequency signal, a power amplifier, and an emitter for measuring the level of nonlinear distortion (“spurious” modulation) in the receiver path of the GAS. It is not known the use of the above devices to determine the level of intrinsic interference of the PSA during its operation.

 Thus, the presence of new significant features in combination with the known ones provides the appearance of the proposed solution with a new property that does not coincide with the properties of the known technical solutions, to control the performance of the PAP by determining the levels of "spurious" modulation in the receiving path (the receiving PAP element and the signal processing unit) , which allows us to conclude that the invention has an inventive step.

 The technical result that is achieved by using the proposed device is that the level of intrinsic interference of the PP is determined directly in the process of its operation with high accuracy.

Claims (1)

A device for determining the level of intrinsic interference of a parametric receiving antenna, comprising a series-connected pump signal generator, a power amplifier and a radiator, a series-connected low-frequency signal generator, a power amplifier and a radiator, a receiving element of a parametric receiving antenna, a signal processing unit and a spectrum analyzer, characterized in that it additionally contains a series-connected calibration low-frequency signal generator, a power amplifier and radiation atelier, switch, one input of which is connected to the output of the receiving element of the parametric receiving antenna, and the other to the output of the signal processing unit, the output of the switch is connected to the input of the spectrum analyzer, while the emitter of the calibration low-frequency signal is located in the immediate vicinity of the receiving element of the parametric receiving antenna, and the receiving a receiving antenna element parametric pre-calibrated for signal reception at the pump frequency ω _n, combinative frequencies ω _n ± ω, Woofer ΔΩ.o - deleterious useful signal Ω, a low-frequency calibration signal Ω

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