SU750758A1 - Hydrophone - Google Patents

Description

(54) HYDROPHONE

I

The invention relates to the field of hydroacoustics, more specifically to electromechanical devices that convert mechanical vibrations of the aquatic environment into electrical signals, and can be used in mobile and stationary devices and underwater acoustics systems.

Hydrophones are known that work with the use of a piezoelectric effect — the verification of technical parameters and the calibration of which are carried out using built-in calibration devices 1.

These hydrophones compare favorably with the widespread types of piezoceramic hydrophones in that their metrological service is economical, simple and does not require dismantling the hydrophone to create artificial calibration and calibration conditions, as is usually done for typical piezoceramic receivers.

At the same time, these analogues have significant drawbacks:

- determination of the sensitivity of hydrophones has a large error of up to 10-f 15 dB;

- Calibration of hydrophones is produced in a narrow band of frequencies determined by the calibration capabilities. radiator;

- graduation of hydrophones is not carried out in the entire working frequency range of the receivers;

- the dynamic range of an idle calibration signal does not provide a high signal-to-noise ratio, which reduces the efficiency and accuracy of metrological operations

10 when they are carried out under the direct conditions of operation of hydrophones.

The closest in technical essence to the proposed is a hydrophone containing a piezoceramic sensitive element with a metallized internal cavity, a calibration device, signal circuits, sealing and fastening elements 2.

With all the simplicity of the hydrophone with a built-in microtelephone calibrator, it has

20 number of drawbacks;

Claims (2)

- low accuracy of self-rolling and determining the sensitivity of the hydrophone due to the large (up to 12 dB) non-uniformity of the frequency response of the microtelephone emitter, especially at the extreme frequencies of the band of the emitted sound signal; - the irregularity of the radiation pattern of the calibration signal due to the design features of the microtelephone; - a limited frequency range of the calibration signal, having an uneven frequency response acceptable for a given calibration accuracy; - low dynamic range of the calibration signal, due to the design capabilities of the microtelephone emitter and the condition for providing the radiation of the calibration signal with a given non-uniformity of the frequency response; - instability in time of the electroacoustic parameters of the microtelephone emitter of the calibration signal, their essential dependence on temperature, humidity, vibration and physical and chemical properties of the materials from which the micro-background is made; -the impossibility of graduating a hydrophone in its working frequency range with the help of a microtelephone emitter of a calibration signal for the reasons indicated in paras. 1,2,3. The purpose of the present invention is to improve the accuracy of determining sensitivity in its entire range of operating frequencies of the hydr background. This is achieved by the fact that the device is supplied with an elec- trostatic pathogen, size. in the internal cavity of the piezoelectric element and made in the form of a metal electrode, installed with a gap in relation to the inside surface of the piezoelectric element, not exceeding 0.015 of its radius, and connected to a source of a HIGHLY high voltage and an alternator of a low voltage operating frequency of the hydrophone. The invention is illustrated in the drawing. The proposed hydrophone contains a piezoelectric sensing sensor, a w element 1 with an internal cavity 2, a signal electrode 3 connected to the hydrophone case 4, a calibration additional electrode 5, fastening and sealing elements 6, a calibration power source 7 and a calibration power source electrode with alternating current 8. When calibrating and calibrating a hydrophone using an integrated electrostatic exciter of the calibration signal, an additional electrode is simultaneously applied to the additional electrode AC voltage and frequency required DC voltage E. 4 instantaneous voltage U |, applied to the electrode is the sum of voltages U | Е UpT sin cot. A uniformly distributed electrostatic attractive force arises between the additional electrode and the metallized inner surface of the sensitive piezoceramic element. The piezoceramics of the hydrophone does not react to the static part of this force, and the reaction voltage corresponding to the response of the piezoelectric ceramics to the variable acoustic pressure of the aqueous medium is produced to the variable part. When E Urn (30-50), the working formula for calibration and calibration of the hydrophone is: Rack. , 85.10-Mn / m, where RZKV. - equivalent acoustic electrostatic pressure on the surface of piezoceramics; E is the voltage from the DC source, in volts; UITI - alternating voltage amplitude from the generator, in volts; d is the gap between the calibration electrode and the inner surface of the piezoelectric ceramics; 8.85 10 f / m is the dielectric constant of air in the gap. As can be seen from the working formula, the effective value of pressure on the surface of piezoelectric ceramics does not depend on the frequency of the excitation voltage, which makes it possible to use its entire working frequency range for calibration of a hydrophone. The sensitivity of a hydrophone at a specific frequency is determined by the Vygilroth output analytically, using the formula Vyd Idrof. the voltage of the response of the piezoceramics hydrophone to a calibration effect, or the same voltage, but the transmitted amplification of the acoustic path and applied to the target recording device (voltmeter with graduation scale in units of pressure, dB); REKB. the calculated value of the electrostatic pressure equivalent to the acoustic pressure of the aqueous medium of a certain magnitude and frequency. When the condition of the constant size of the gap between the electrodes in the inner cavity of the sensitive element is met, the error of self-calibration and calibration of the hydrophone in the whole range of its operating frequencies will be 3 times lower than that of the prototype, and will not exceed ± 2 dB. 5 The proposed design, the hydrophone is advantageously different in its capabilities: - the frequency range of the self-calibration of the hydrophone is expanded, its calibration becomes possible without the involvement of additional tools and devices; - it is possible to promptly carry out metrological servicing of the hydro background with the best indicators of accuracy of determining sensitivity, with an increased signal-to-noise ratio, which causes the implementation of this proposal in systems installed in places with increased environmental noise; - it is possible to use the proposed 1H hydrophone under conditions of high hydrostatic pressure, since the high efficiency of the hydrophone at great depth is achieved by creating an electrostatic counterpressure in the internal cavity with the help of an additional electrode and a source of constant voltage; - The reliability and durability of a calibration device embedded in a hydrophone is improved, as it no longer contains unreliable radio elements. The proposed hydrophone can be used, for example, in the acoustic paths of deep-water stationary or mobile measuring systems, in marine seismic survey equipment. Using it will allow you to get a positive effect on equipment maintenance due to the efficiency, simplicity and sufficient accuracy of the results of calibration and calibration of the hydrophone directly under the operating conditions without dismantling, using model and other means of providing metrological service. Claims of the invention A hydrophone containing a piezoceramic sensitive element with a metallized internal cavity, a calibration device, signal circuits, sealing elements and. mount, characterized in that, in order to increase the nausea of determining its sensitivity in the working frequency range, the device is equipped with an electrostatic exciter, spaced in the inner cavity of the piezoceramic sensitive element and made in the form of a metal electrode installed with a gap in relation to. the inner surface of the piezoceramic sensitive element, not exceeding 0.015 of its radius, and the joint with the inputted source of constant high voltage and generator (m variable low voltage operating frequency of the hydrophone. Sources of information taken into account during the examination 1. US Patent No. 3118125, Cl. 340-8, published 1964. 2. USSR author's certificate number 193325, l. H 04 R 1/44, 1966 (prototype).