{"title":"Comparison of the Waveguide and Phase–Energy Invariants in the Near-Field Zone of Acoustic Illumination","authors":"S. P. Aksenov, G. N. Kuznetsov","doi":"10.3103/s1541308x24700298","DOIUrl":null,"url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>In many problems of practical importance the interference structure of broadband-signal intensity field in shallow water is determined by the close-to-unity value of the waveguide invariant (WI) β (which is often referred to as the Chuprov invariant). This circumstance is used in ranging, when estimating the distance to the source or its relative velocity. However, the characteristics of the β invariant in deep sea have been studied insufficiently. The WI properties in the near-field acoustic-illumination zone (NFAIZ) of deep sea are investigated below. Its value is shown to be unstable: WI changes in a wide range and actually is not an invariant. Another value—phase–energy invariant (PEI) β<sub>ef</sub>—proved to be more promising in deep sea. In the NFAIZ of deep sea, at real depths of sources and PEI detectors, it is equal to unity with a high accuracy (except for the interference minima zones). It is also found that coherent addition of Fourier components in the complex plane can be implemented in the NFAIZ, provided that a correction to phase variation is introduced when summing spectral densities along ridges. To this end, one must take into account that the Fourier-component phase on a ridge changes almost linearly with an increase or decrease in frequency. In principle, consideration of these characteristics of signals makes it possible to solve more efficiently various applied problems of acoustics. However, to implement this possibility, it is necessary to develop a fairly complex algorithm of signal power accumulation in the frequency–space domain.</p>","PeriodicalId":732,"journal":{"name":"Physics of Wave Phenomena","volume":null,"pages":null},"PeriodicalIF":1.1000,"publicationDate":"2024-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Physics of Wave Phenomena","FirstCategoryId":"101","ListUrlMain":"https://doi.org/10.3103/s1541308x24700298","RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"PHYSICS, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
Abstract
In many problems of practical importance the interference structure of broadband-signal intensity field in shallow water is determined by the close-to-unity value of the waveguide invariant (WI) β (which is often referred to as the Chuprov invariant). This circumstance is used in ranging, when estimating the distance to the source or its relative velocity. However, the characteristics of the β invariant in deep sea have been studied insufficiently. The WI properties in the near-field acoustic-illumination zone (NFAIZ) of deep sea are investigated below. Its value is shown to be unstable: WI changes in a wide range and actually is not an invariant. Another value—phase–energy invariant (PEI) βef—proved to be more promising in deep sea. In the NFAIZ of deep sea, at real depths of sources and PEI detectors, it is equal to unity with a high accuracy (except for the interference minima zones). It is also found that coherent addition of Fourier components in the complex plane can be implemented in the NFAIZ, provided that a correction to phase variation is introduced when summing spectral densities along ridges. To this end, one must take into account that the Fourier-component phase on a ridge changes almost linearly with an increase or decrease in frequency. In principle, consideration of these characteristics of signals makes it possible to solve more efficiently various applied problems of acoustics. However, to implement this possibility, it is necessary to develop a fairly complex algorithm of signal power accumulation in the frequency–space domain.
期刊介绍：
Physics of Wave Phenomena publishes original contributions in general and nonlinear wave theory, original experimental results in optics, acoustics and radiophysics. The fields of physics represented in this journal include nonlinear optics, acoustics, and radiophysics; nonlinear effects of any nature including nonlinear dynamics and chaos; phase transitions including light- and sound-induced; laser physics; optical and other spectroscopies; new instruments, methods, and measurements of wave and oscillatory processes; remote sensing of waves in natural media; wave interactions in biophysics, econophysics and other cross-disciplinary areas.
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