E. P. Tikhonov

In the modern ultrasonic diagnostic electronic equipment have application mainly impulsive systems of measurement of speed of a blood stream. In these systems for the spatial sanction of measured speed of a blood stream probing ultrasonic signal is formed as a pulse which together with width of the diagram of orientation define resolution impulsive systems. Doppler frequency is in a sound range and influences duration of a ultrasonic pulse. Therefore increase of speed and time resolution of systems of diagnostics is directly defined by a method and algorithm of measurement Doppler frequencies. The purpose of article is development, and a theoretical substantiation of an adaptive method and algorithm of measurement Doppler frequencies with reduction of time of measurement up to the fourth part of her period. In a basis of the given method is put the iterative method determining adaptive algorithm of search of a time interval of digitization of a harmonious signal which begins with initial value. In the analytical form of recording of algorithm on an initial time interval the difference between the current value of a signal and his restored value is defined, for example, according to linear function of restoration. Difference compare to the transformed peak value of the same signal in an index point of an interval. By result of comparison accord-ing to algorithm initial value of an interval up to the established value is corrected. On the basis of the analysis of convergence of the suggested the algorithm executed in article to established value (a motionless point) the measuring equation for definition of required value of frequency of a harmonious signal is received, and time of transient from initial initial up to the established required value is appreciated. As shown on the basis of modelling, time of transient equal to time of measurement of required frequency of an entrance signal, does not exceed a quarter of the period. Results of modeling are illustrated by the figures.