SU894552A1 - Method of ultrasound speed determination - Google Patents

Description

() METHOD OF DETERMINING THE SPEED OF ULTRASOUND

one

The invention relates to a measurement technique and can be used to determine parameters and indicators of liquid and gaseous media functionally dependent on the speed of ultrasound.

There is a known method for measuring the speed of ultrasound, at which frequency-manipulated signals are formed in an auto-circulating circuit in time with an auto-circulating period}.

The disadvantage of the known method is that limiting the amplitude of the signal before frequency detection introduces a variable component of the signal delay in the synchro-ring, where the remaining component of the time delay is constant, which reduces the accuracy of measurements.

The closest to the invention is a method for determining the speed of ultrasound, in which ultrasonic waves are excited in a medium, received after passage through the medium, converted into electrical oscillations, amplified, detected by means of electrical units, which generate ultrasonic waves in the medium again, and ultrasound velocities are judged by the reciprocal of the measuring time interval, for which it is subtracted from the autocircuit period of the electroacoustic process su mu delay time of ultrasonic waves in the converters and the delay time of electrical oscillations in the electronic units 2}.

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A disadvantage of the known technical solution is low measurement accuracy due to the fact that only the constant component of the parasitic delay time is compensated.

The purpose of the invention is to improve the accuracy of measuring the speed of ultrasound.

Claims (2)

This goal is achieved by the fact that the time delay between the main and auxiliary pulses is additionally subtracted from the period of autocirculation, and the latter forms at the time when the leading edge of the detected fluctuations of the level twice the level of the formation of the main pulses is reached. FIG. Figures 1 and 2 show diagrams that explain the proposed method; in fig. 3 is a diagram of an apparatus for implementing the method. FIG. Figure 1 shows the received acoustic impulse after its transformation into electrical voltage, amplification and detection, in the coordinate voltages x, (and) and time (t). Moreover, and 2Uq3 are, respectively, the formation levels of the formers of the main and auxiliary pulses, C and ". + Dj, respectively, the variable components of the parasitic delay time from the instability of the coupling time to the leading edge of the received electroacoustic pulse when the signal amplitude fluctuates and the emission frequency changes for the levels of Up and 2U (p, ta is the time interval between the moments of received edge signal when the front reaches, respectively, the levels Uqi and 2Uep, t is the oscillation period of the main harmonic component of the emitted pulse, I and II are the shape of the input signal, respectively, at the maximum and minimum values The amplitudes of the oscillations. In Fig. 2, T shows the period of autocirculation of pulses according to the method outlined, which falls with the period of autocirculation by a known method, al and 2 cm are the components of the constant parasitic delay time, respectively , - the delay time in the electronic circuit (determined, mainly, by the generator switching on delay) - the delay time in the transducer membranes, ISu - coincides with Cs in FIG. 1, TM - measuring time interval, equal to the time of passage -. ultrasound oscillations in the medium to be measured (less from the measurable part of the period of autocirculations in the known method by the amount -Si). A device for implementing the method comprises a time meter 1, a hyperbolic transducer 2, a delay device 3, the input of which is connected to the output of an additional pulse former, the input of which is connected to the output of the detector (not shown). The method is implemented as follows. When the amplitude of the received signal is changed, as well as when the radiation frequency (Fig. 1) is changed, the interval interval changes in proportion to the occurrence of a variable component of the time delay in the back-cycle period (in the synchro shaper unit) and in the measurement accuracy . Therefore, it was proposed to indirectly measure the interval c through (/ g and subtract the last one from the measurement interval by fixing the moment of occurrence of the front of the received signal at 2U. After subtracting the interval / Cj from the period T of autocirculation taking into account the preliminary subtraction constant time component Sdl + 2Cm delay (Fig. 2), we have a measuring interval T ,, free from both constant and variable component of the parasitic delay time, and therefore to be measured. The x blocks (Fig. 3) are compensated for the variable component (Tj) of the parasitic delay time by switching on the additional generator, the response threshold of which is set twice as high as the response threshold of the main generator (synchrocket), and the delay device 3 is set to compensate for the constant parasitic time component the delays in the synchrogun, i.e. the propagation time of the signal in the device 3, is chosen equal to the sum of the time of SEA + 2l. As a result of switching on the device blocks (Fig. 3) in the autocirculation mode of the signal, the pulses from the output of the main shaper of the sync ring set the trigger 1 to the first steady state, and the pulses from the output of the additional shaper t through the device 3 delay through the interval a + Cel + 2tw of time trigger 1 to the second steady state. The time interval for the occurrence of pulses between the output of the main shaper of the synchro-ring and the output of the additional shaper taking into account the signal delay by time C in the main shaper (not shown) and by time + in shaper 4 is equal to Jj. As a result, the measuring interval T at the output of unit 1 is less than the period T of autocirculation by the value of cg + (ds + Zt, which causes an increase in the accuracy of ultrasound velocity measurements. The described method of determining the ultrasound velocity allows an order and more accurate measurements in a wide range radiation frequency during fluctuations of the amplitude of the received signal. Invention A method for determining the speed of ultrasound, in which ultrasonic waves are excited in a medium, is taken after passing through a medium, Into electric oscillations, by means of electrical blocks, they amplify, detect, form 26 main pulses, which again excite ultrasonic waves in the medium, and ultrasound speeds are judged by the reciprocal of the measurement time interval, to obtain which the sum of the delay time is subtracted from the autoacoustic circulation period. ultrasonic waves in the transducers and the delay time of the electrical oscillations in the electronic units, characterized in that, in order to increase the measurement accuracy, from The auto-circulation code additionally subtracts the time delay between the main and auxiliary pulses, and the latter generates at the moment when the leading edge of the detected oscillations reaches a level twice as high as the main pulses. Sources of information taken into account in the examination 1. USSR author's certificate number, cl. G 01 N 29/00, 1976. 2. USSR author's certificate number KL. G 01 N 29/00, 1976 (prototype). . Cft, g fie.g srag