SU655959A1 - Digital ultrasonic velocity meter - Google Patents

Description

the second and second keys, the output of the stable frequency generator is connected to the third key c to the frequency divider, the output of which is directly connected to the first key, as well as through the cascade aa of the switch to the second key, the outputs of the first and second keys are connected to the OR circuit, the output which is connected to the subtractive input of a differential counter, the outputs of which are connected to the measuring unit, and the summed up input of the differential counter is connected to the output of the third key, the second input of which is co-amped with the third trigger, the second control Its input through the selector is connected to one of the ultrasonic transducers.

FIG. Figure 1 shows the structural scheme of the ultrasound velocity meter; in fig. 2 - timing diagrams illustrating the operation of the meter.

The meter contains a pulse generator 1, connected through diodes 2 and 3 to two ultrasonic transducers with transition layers 4 and 5, as well as to the first control inputs of the second, second 7 and third 8 triggers and to the reset input of the difference counter 9. The first and second converters 4 and 5 are connected respectively to the first 10 and second 11 selector pulses, the outputs of which are connected to the second control inputs of the first and second triggers, the outputs of which are connected to the control inputs of the first 12 and second 13 keys. The meter also includes a stable frequency generator 14 ,. the output of which is connected to the third key 15 and to the frequency divider 16. The output of the frequency divider is directly connected to the nepaoi key | and via delay cascade 17 to the second key, the outputs of the first and second keys are connected to the OR circuit 18, the output of which is connected to the subtractive input of the differential counter 9. The outputs of the counter 9 are connected to the measuring unit 19, and the summing input of the differential counter of the third key 15. The second input of the key 15 is connected to the output of the third trigger 8, the second control input of which, through the selector 20, is connected to the single 5 g of the ultrasonic transducers.

The meter works as follows.

At the initial moment of time d (Fig. 2, a), the pulse generator 1., through diode strings intended for isolating ultrasonic transducers, excites both ultrasonic transducers 4, 5 through the reflected and received signals and simultaneously into the first control inputs The states are the first 6, the second 7 and the third are 8 triggers, and the difference counter 9 is in the zero state. During the action of an electric pulse, ultrasonic transducers excite ultrasound waves in the transition layers (Fig. 2, b), which propagate through them, pass the medium under study and excite ultrasound transducers through the transition layers (Fig. 2, c). Some of the energy of the ultrasonic radiation emitted into the medium under study is fluctuating due to the difference in the acoustic impedances of the layers and the medium reflected from the boundaries of the transition layers of the medium under study. The reflected ultrasonic pulses (Fig. 2, d, e.) Are converted by ultrasonic transducers into electrics and selected using selectors 1O and 11. At the same time, the time and duration of the selection are chosen so that only the pulses reflected from the layer-Medium edge are selected.

Reflected impulses that have a smaller amplitude than probing ones do not change the state of flip-flops 6 and 7 due to losses in the transition layers and partial reflection. The aforementioned reflected cvirnaiTbi in selectors 10 and 11 are converted into short pulses and from their outputs go to - second control inputs of flip-flops 6 and 7, transferring them to the zero state (Fig. 2, e, g.). Thus, the pulse durations at the outputs of the flip-flops 6 and 7 are equal to the double delays of the 2 C ultrasound and 217.2 in the transient layers of the ultrasonic transducers.

Negferyvnye oscillations. From the output of the generator of a stable frequency 14 (Fig. 2, with a repetition period equal to, for example, 1 MKS, arrive at frequency divider 16 with a division factor of 2. From the output of the divider, the pulses (Fig. 2, k) go directly on the first key 12 and through the delay stage 17 - on the second key 13, the delay time T of the cascade 17 is selected from the condition O T, -t.

Podpodovateligost pulses from the output

2 tr key 12, consisting of N - -, -ff

pulses (fig, 2, l), and another sequence from the output of the key 13, co2 z go of NI, 7- pulses

(Fig. 2, m) are applied to the OR circuit, the output of which is a sequence consisting of N 3 N pulses. These pulses come to the subtracting input of the counter 9.

The trigger 8, the selector 20 and the key 15 select the signal of direct passage through the test medium (Fig. 2, c). The pulses from the output of the key 15 are fed to the summing input of the differential cqeiv chica 9. The number of pulses received

the total input (Fig, 2, n),

where a and is the distribution time of the injury of the ultrasonic volry through the test medium. Total extinguished pulses recorded in difference counter 9 (Fig. 2, p), H

or . where 4o "1G", G, 1Gg

Thus, the transit time of the ultrasonic wave through the transition layers is excluded from the measurement result. As a result, the counter records the number of pulses equal to the numerical value of the duration of the measured time interval in micromsec-C outputs of the differential counter 9, the code is fed to the inputs of the meter area, in which the ultrasound velocity is calculated from the known measurement base.

The digital ultrasound velocity meter eliminates the measurement error caused by the instability of the acoustic properties of the transient layers of the ultrasound transducers in the measurement process, and therefore has a high accuracy. In addition, the proposed meter allows to obtain a digital value of the speed of ultrasound in single and multiple measurements, which makes it possible to automate control systems based on the determination of the speed of ultrasound in a controlled environment, and also expands the scope of application of ultrasonic measuring instruments.

Formula of invention

A digital ultrasound velocity meter containing a pulse generator,

Two ultrasonic transducers and two triggers, characterized in that, in order to improve measurement accuracy, one two diodes, two reflector selectors, three keys, OR circuit, delay stage, frequency divider, third trigger, stable frequency amp, a selector, a different 1st meter and a measuring unit, while the pulse generator through diodes is connected to the first control inputs of the first, second and third triggers and to the reset input of the differential meter and to the ultrasonic transducers connected to u with the first and second reflectors of the reflected pulses, the outputs of which are connected to the second control inputs of the first and second triggers, the outputs of which

connected to the control inputs of the first and second keys, the output of the stable frequency generator is connected to the third key and to the frequency divider, the output of which is directly podklk ™

The first key and the second key are connected to the OR circuit, the output of which is connected to the subtractive input of the differential calculator, the outputs of which are connected to the unit of measurement, and the summed input of the difference counter is connected to the output of the third key. key, the second input of which is connected to the output of the

This trigger, the second control input of which through the selector is connected to one of the ultrasonic transducers.

Sources of information received in

attention during examination

1. Author's supervised USSR N 5328О7, cl. G O1 N 29 / OO, 1975.

2. USSR Author's Certificate No. 502324, cl. Q O1 N 33/34, 1974.

655959