I.V. Baranov - Ph. D. (Eng.), Leading Engineer of Open Company Enterprise "KONTAKT-1". E-mail: postmaster@ivb.ryazan.ru
V.A. Bolonin - Leading Engineer of Open Company Enterprise " KONTAKT -1". E-mail: skb@kontakt-1.ru
V.M. Davidochkin - Ph. D. (Eng.), Chief of Department of the Microwave Oven of Devices and Aerials of Open Company Enterprise " KONTAKT -1". E-mail: skb@kontakt-1.ru
V.V. Ezerskiy - Dr. Sc. (Eng.), Professor, Chair of Radio Management and Communication, Ryazan State Radio Engineering University. E-mail: ezerski@yandex.ru

In many areas of human activity there is a requirement for operative contactless measurement of a thickness of ice. Possibility of measurement of a thickness of ice allows to raise essentially safety at carrying out of various researches in interests of natural sciences, the organisation of ice automobile lines and crossings, fisheries from ice and carrying out of salvage operations. At measurement of a thickness of ice by a contactless method by means of a radio range finder there are some challenges. It is necessity of maintenance of high resolution, the big instant dynamic range of entrance signals in connection with a wide range of thickness of ice, presence of a snow cover on ice with a dense ice crust, plural rereflections of signals from surfaces of ice and an aerial edge, necessity of detection of presence of water on surfaces of ice and character of the subglacial environment and strong differences of properties of ice on different reservoirs. Modernisation of a method of measurement with use is considered is frequency the modulated range finder providing use of a method of nonlinear least squares for increase of resolution and a method of recognition for definition of character of the subglacial environment. Modernisation provides a some improvements a method. The first - use of the reference signal, which size is used for definition of a parity of levels of the various reflected signals. Position of a reference reflector gets out on half of distance between an antenna and top surface of ice. The second - before measurements on a concrete reservoir is carried out calibration in which process parametres which allow to define reliably water presence on ice, character of a spreading surface are defined and register in memory and to lower an instant dynamic range of signals. The third - is used adaptive change of number of samples of processed signals and algorithm of processing at change of a thickness of the ice, allowing to accelerate procedure of definition of a thickness of ice. On the basis of these changes procedure of carrying out of measurements of a thickness of the ice, providing preliminary calibration on a concrete reservoir is developed at the motionless carrier of a measuring instrument and after that consecutive carrying out of measurements. The first measurements is spent at number of samples of the signal chosen proceeding from the greatest thickness of ice by means of a method of the high spectral permission. Movement of the carrier and adaptive change of number of samples and a processing method further begins. The function chart of the measuring instrument providing performance of all specified actions and operations is developed. Results of experimental check of a breadboard model of a measuring instrument are resulted.