摘要:The article considers the issue of diagnosing the condition of multilayer elements and structures. Probing methods are considered. A multiphase detection method has been proposed to generate diagnostic information that allows the reflected signals from several consecutive layers to be obtained. The reflection distance is determined for each layer. The presentation of a two-dimensional model of structural sounding in the presence of two objects of study was considered. The three-dimensional model of search of objects of research of concrete designs considered in work provides probing by spherical waves of a detail, measurement of phase shifts of signals reflected from internal objects of research in three points. Division by means of one of mathematical models of signals are reflections from each object of research and determination of coordinates of objects of research and can by means of the mathematical model was represent. The equipment of a measuring instrument was developed to study the analytical multifrequency phase method of distance measurement. This system can be used to diagnose defects in multilayer structures that can transmit radio waves. Also it can be used for quality control of the put coverings and for the analysis of thickness of composite materials, isolation layers in the equipment.