SU474361A1 - Method for automatic measurement of acoustic attenuation coefficient - Google Patents

Description

pulses arriving at the acoustic transducer are supplied to the controlled element, for example, a current generator installed in the discharge circuit of the energy storage device (capacitor).

From one of the first pulses of a series (for example, the second) the accumulator is charged to the amplitude value of the pulse, then discharged through the controlled element (see Fig. 1, c), the parameter (current value) of which changes discretely with the arrival of each clock pulse , thereby changing the slope of the discharge curve.

The accumulator discharge curve and the series of reflected pulses (see Fig. 1.6) are compared with the discriminator (see Fig. 1, d), and at the time of the discharge discharge curve, the discriminator (see Fig. 1, d) forms impulses.

At the beginning of the measurement cycle, the parameter of the controlled element is set such that. the slope of the discharge curve of the energy storage device corresponds to the minimum attenuation of acoustic oscillations in the medium under study.

The end of the measurement cycle is determined by issuing the command "Stop a parameter change (see Fig. 1, e), indicating that the curve is exceeded by one or several pulses (depending on the program).

This is due to the fact that in the real case the envelope of the reflected pulses is not linear (see Fig. 2, a) and in order to reduce the error of the attenuation coefficient change, the command "Stop changing the parameter and registering the parameter should be at the time when the curve yes corresponds to position 1 in fig. 2, a and 2 and the output of the dicrimiator form two pulses (see Fig. 2.6), and in a momeite, iairimer corresponding to the position 2 curve and on the output of the pulse discriminator.

When measuring the attenuation of acoustic oscillations by the pulsed method, the frequency of clock pulses / ton (probe pulses), as a rule, is 0.5-2 kHz. If the attenuation varies in the range from "min to a.chax" ("min and max" are the minimum and maximum attenuation coefficients corresponding to the initial and final parameters of the controlled element) and the change in the parameter of the controlled element with each clock pulse corresponds to

attenuation change Aa (see

100

FIG. 1, c), then the maximum cycle time for measuring Gizm will be, where at

/ t

 KHZ, s and Gizm 0.1 s, which confirms the speed and accuracy of the attenuation measurement.

Subject invention

Method for automatic measurement of acoustic attenuation coefficient

and by emitting acoustic signals into the test medium and analyzing received echo pulses, including their logarithm, characterized in that, in order to increase the accuracy and speed of measurements by accumulating and discharging electric charge proportional to the amplitude of one of the pulses, with a subsequent increase in their angle slope at each measure determined by the frequency of the following aku

the acoustic impulses introduced into the medium form the reference discharge curves defining the slope of the envelope of the echo pulse series, and successively compare the echo pulse series with the corresponding reference curves, and the attenuation coefficient of the acoustic oscillations is judged by the number of cycles compared to instant of exceeding the reference discharge curve by one or several echo pulses.

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