SU1656336A1 - Device to meter ultrasonic velocity - Google Patents

Abstract

The invention relates to non-destructive control methods and can be used in the study of the physicochemical properties of various materials. The purpose of the invention is to improve the accuracy by reducing errors in the amplifier and increasing the output by: automating the counting of the half-wave number of the signal. From the sequence of reflected pulses, a given nth pulse is extracted. Shaper 9 cuts off the video impulse from it with a duration equal to the period of ultrasonic vibrations. After element 12, an Exclusive OR, a rectangular pulse is formed, the duration of which is proportional to the change in gain of amplifier 5. This change is extracted by a circuit from analog-digital converter 17, digital-to-analog converter 18 or 19, and comparison unit 20. A control & inrush signal is fed to amplifier 5. The reflection number is indicated by a counter 13. 2 Il.

Description

The invention relates to non-destructive methods of control and can be applied in the study of the physicochemical properties of various materials in solid and liquid states.

The aim of the invention is to improve the measurement accuracy by reducing the error caused by the difference in phase shifts of amplifiers, nonlinear and frequency distortions, as well as precision support for the amplitude of the output signal, and increasing productivity by automating the half-wave number counting process.

Figure 1 shows the structural diagram of the device; figure 2 - diagrams of electrical processes.

The device contains a generator 1 connected to an acoustic transducer 2 mechanically connected with the controlled medium 3 and an electronic switch 4 connected in series, an amplifier 5, a detector 6, a counting unit 7, and the second output of the unit 7 is connected via its delay line 8 to its the second input, as well as serially connected shaper 9 unipolar signal, inverter 10, selector 11 and element 12 Exclusive OR, counter 13, the first input of which is connected to the output of selector 11, trigger 14. whose input through a double switch Juchatel 15 is connected to the second output of the counting unit 7, and the output is connected to the first input of the comparator 16, the output

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which is connected to the second inputs of the Exclusive OR element and counter 13, analog-to-digital converter 17 (ADC), the output of which is connected to the inputs of the direct 18 and inverse 19 digital-analog converters (DAC), and the input is connected to the output of the element 12 Exclusive OR, block 20 comparison, the first and second inputs of which are connected to the outputs of the direct 18 and inverse 19 DAC, and the output is connected to the second input of the amplifier 5, the autorunter unit 21, the output of which is connected to the first input of the generator 1, and the input is connected to the output of the amplifier 5, frequency meter 22 , entrance to second connected to the output of the generator 1, the output of the amplifier 5 is connected to the second inputs of the selector 11 and the comparator 16, the output of the selector 11 is connected to the second input of the generator 1, the output of which is connected to the input of the electronic switch 4, the input of the driver 9 is connected to the first output conversion unit 7.

A device for measuring the speed of ultrasound works as follows.

When excited by the generator 1 of the ultrasonic transducer 2 by a pulse 23, the latter begins to oscillate and the oscillations are transmitted to medium 3. Reflecting from the interface between two media, the ultrasonic oscillations through the electronic key 4. Go to amplifier 5. The key 4 is closed during the action of the powerful pulse 23. The amplified oscillations 24, in the form of short radio pulses, arrive at detector 6 and are converted into video pulses 25, and then go to block 7. Depending on the position of the dual switch 15, each n-th pulse (for example) goes to driver 9 and through line 8 delay - at its second entrance. The switch 15 is always placed in such a position that if the n-th pulse arrives at the shaper 9, then the trigger 14 receives a (n-1) pulse, which is set to 1 by the falling edge (n-1) by the pulse, and th pulse is set to its original position, i.e. trigger 14 is in unit state 26 for a time ti, during which the n-th reflection pulse passes on comparator 16. The shaper 9 cuts off part of the n-th video pulse with a duration equal to one period of ultrasonic vibrations, and through the inverter 10 enters the first input of the selector 11, and the second input receives a radio pulse 24 from the amplifier 5. A negative half-wave 27 is formed at the output of the selector 11, equal to half the period radio pulse 24. This half-wave arrives at the first input of element 12 Exclusive OR, and the second input receives a series of pulses 28 of the selected n-th reflection from the output of comparator 16. At the output of element 12, one is obtained

impulse 29, the duration of which is equal to the difference and durations of D | / impulse 30 between two pulses from the comparator 16 and the selector 11 at the level of V0n - the reference response of element 12, i.e. depending on the amplitude of the selected half-wave, the phase of two pulses will change at the level of V0n and the duration 2 of pulse 30 will change accordingly. Pulse 30 will be fed to the input of ADC 17, which will convert 5 seconds to digital form and fed to the DAC 18 and 19. If the amplitude of the selected half-wave is less than the specified one, then the inverse DAC 19 is triggered and through the comparison unit 20 is fed into the feedback circuit of the amplifier

0 5 in such a way that the amplitude of the selected half-wave increases, and if the amplitude of the half-wave is greater than the specified one, the direct DAC 18 is triggered and through the comparison unit 20 the half-wave amplitude decreases 5 s.

Since feedback can be used to automatically keep the measurement error of the output signal of the amplifier within acceptable limits, i.e. it has a hysteresis loop, then in this case, the phase shift of two pulses transforms into a pulse duration of 30 using an ADC and a DAC 18 or 19, the pulse width is divided into m levels, possibly in t

5 times to reduce the error caused by changes in the amplitude of the output signal. From the output of the selector 11, the pulse arrives at the first input of the counter 13, which prohibits further counting, the second input is received

0 counting pulses from the output of the comparator 16 and if the first half-wave is selected, then on the counter the reading will be O, if is the second, then the readings will be equal to the measured frequency readings with a frequency meter,

5, if a third half-wave is selected, then the counter reading will double, and so on.

If the meter readings are not equal to O and are not multiples of the frequency meter readings, then the measurement of the first, subsequent, etc., takes place during one cycle. half wave Thus, according to the meter readings, it is possible to judge the number of the selected half wave during one measurement cycle, which ultimately increases the productivity of labor. The pulse from the output of the selector 11 is fed to the second input of the generator 1, which is restarted to a new measurement cycle. In the absence of pulses at the output of the amplifier 5, the autorunter block 21 outputs pulses with

with its own repetition period. Thus, using a single amplifier, we achieve a reduction in measurement error due to a decrease in nonlinear and frequency distortions and phase shifts caused by unequal depth of negative feedback.

Claims (1)

Invention Formula A device for measuring the speed of ultrasound, comprising a serially connected autorun unit, a generator and an acoustic transducer, an amplifier whose output is connected to the autorun block input, a detector, a counting unit and a delay line whose output is connected to the adjusting block input, and a frequency meter connected To the output of the generator, characterized in that, in order to increase accuracy and productivity, it is provided with connected by a trigger, a Comparator element Exclusive OR, an analog-to-digital converter, a digital-to-analog converter and a comparison unit, the output of which is connected to the control input of the amplifier, connected in series by a single-side signal former, an inverter and a selector whose output is connected to the second input of the Exclusive OR element control input of the generator, a counter connected by inputs to the outputs of the selector and comparator, an inverse digital-to-analog transformer included between course of the analog-digital converter and a second input of the comparing unit, and a switch connected between the output sealer unit and trigger inputs and shaper unipolar of signature in the output of the amplifier is coupled to the second input selector and the comparator. fie-i 23 $ 2 PPIPQ tt v thirty ...,.  I Ј7 - -3tJ- | abt P P v "& L 2.2