S.R. Heister, N.G. Parhomenko, A.S. Heister
The tasks of object recognition and object length measurement are generally solved separately. Simultaneous solution of these problems using inverse synthetic aperture radar is considered in the article. Azimuthal radiolocating portraits contain the information about object class and object overall dimensions. The portrait is formed using inverse antenna aperture synthesis with total focusing. The portrait is a collection of complex amplitudes of signals that correspond to different resolution elements of object in azimuthal plane.
Assumption of equiprobable appearance of objects of different types in different classes makes it possible to suppose that reflection power of object has uniform distribution in azimuthal plane. The number of elements of azimuthal radiolocating portrait with nonzero values contains the information about object length. On the basis of that statement the task of object length measurement can be interpreted as a task of class recognition of object of definite length among the objects of different types and lengths. As a result the tasks of object recognition and object length measurement can be solved simultaneously with a help of device that produce multi-channel processing of object’s azimuthal radiolocating portrait. Each channel of the device corresponds to definite object length.
Solution of tasks of object recognition and object length measurement is based on Bayes criterion of minimum average risk. Normal distribution law of complex amplitudes of azimuthal radiolocating portrait is validated. Statistical model of azimuthal radiolocating portrait that is multidimensional probability density of collection of complex amplitudes of the portrait is designed. Information about object length value and its class is encoded in covariance matrix of comlex amplitudes of azimuthal radiolocating portrait.
According to selected performance criterion the rule of object recognition and length measurement is developed also statistical synthesis of azimuthal radiolocating portrait processing algorithms are performed. According to the synthesis results the structure of the recognition and length measuring device uses azimuthal radiolocating portrait is designed.
Aircraft, automobiles and track-type vehicles can be the object of radiolocation. Quality level of recognition and object length measurement depends on the conditions of observations and number of channels used in azimuthal radiolocating portrait processing. Etalons of the channels correspond to definite length of objects.