SU1357724A1 - Sound velocity meter - Google Patents

Abstract

The invention relates to non-destructive testing and can be used to create automated control systems. The aim of the invention is to improve the measurement accuracy by transferring a signal to a lower frequency region of the spectrum. Since the receiving path is not used for some time after the probe pulse has been emitted, the time expander produces a signal in a form similar to the received, but with a reduced, frequency. As the sampling rate of the signal does not decrease, the accuracy of the measurement is improved. 1 il. 00 ate

Description

The invention relates to non-destructive control and can be used to create automated control systems.

The aim of the invention is to improve the measurement accuracy by transferring a signal to a lower frequency region of the spectrum.

The drawing shows a structural diagram of the sound velocity meter.

The sound speed meter contains a generator 1 and a radiating transducer 2 connected to it, a receiving transducer 3, interconnected counter 4 and processing block 5, as well as a crystal oscillator b, temporary conversion block 7 made in the form of a serially connected frequency divider 8, line 9 delay, time extender 10 and comparator 11, the input of the frequency divider 8 and the second input of the delay line 9 are connected to the output of the crystal oscillator 6, the output of the frequency divider 8 is connected to the input of the generator 1, the output of the comparator 11 oedinen a second input temporary dilator 10j input counter 4 and the input of the processing unit 5 ° vkod receiving transducer 3 is connected to the third input of the dilator 10 temporarily, the output of the delay line 11 is connected to the second input of the counter 4.

The sound speed meter operates as follows. The quartz oscillator 6 produces pulses with a frequency f. At the output of the frequency divider 8, a sequence of pulses is formed with a frequency f

F if, where N is the ratio of NP 0

Neither the frequency divider 8 is such that

N - 2-, where 1 is the measurement base

min is the minimum possible velocity of ultrasound.

1 1 pulses from the output of the divider 8 frequencies simultaneously arrive at the input of the generator 1, start it, and to the first input of the delay line 9. The excitation pulses arrive at the radiating transducer 2, are converted therein into ultrasonic pulses, and are emitted into the test medium. The received signals from receiver 3 have time shifts relative to the moment of radiation, equal to

k s

(3)

0

five

These pulses in the converter 3 are converted into electrical ones and are fed to the input of the temporary expander 10.

Simultaneously with the moment of radiation, the pulse from the output of the frequency divider 8 brings the delay line 9 to the initial state. In this case, the pulses from the output of the quartz oscillator continue to flow; therefore, the pulses at the output of the delay line 9 have time shifts relative to the moment of radiation, equal to

0

N. t.

,

 R

) l

where N is chosen from the condition

1o

N,

 - MLKS -o

(four)

(five)

25

These pulses simultaneously arrive at the first input of the temporary spreader 10, start it, and into counter 4, in which they are converted into code over time. Since the start-up pulses 30 of the time expander 10 arrive a little earlier than the signals that have passed the test medium, the time expander 10 takes a measurement at the entire signal delay time in the test medium, but only its part defined by the expression

35

,

40

45

50

55

In this case, a temporary expander 10 generates a signal in the form corresponding to the signal received by the ultrasonic transducer 3, but extended in time. This pulse arrives at the input of the comparator 11, to which the reference voltage U is applied. The voltage signal with the reference voltage At the output of the comparator 10, a voltage pulse is generated, the leading edge of which records the counter code 4 in the processing unit 5 and the trailing edge resets the counter 4 and the time extension to the initial state rer 10, whereupon the entire measuring cycle is repeated. In this case, the value of the code N at the output of the counter 4 is equal to

N - & t

where ut is the step size of the time dilator 10 ,. chosen depending on the required accuracy of measuring the time y-T. ,

Since the calculator receives the code N corresponding to the numerical value of the time interval & & rather than the entire time of propagation of ultrasound TO, the code is entered into the processing unit 5 before the measurements.

M N.

ut

corresponding to the numerical value of t,.

In processing block 5, the N code is summed with the M code and, depending on

U 1

WITH

(M + N) At

to

the digital value of the ultrasound velocity in the medium is calculated. The measurement result is presented in digital form on the display of the processing unit 5. Transforming the spectrum of the signal into the low-frequency region allows an increase in measurement accuracy at the same sampling rate.

The time extender 10 can be performed similarly to the blocks building structure A.A.Olohtonov Editor G.Volkova Tehred M.Hodanich Proofreader A.T.

Order 5988/38 Circulation 500 Subscription

VNIIPI USSR State Committee

for inventions and offenses 113035, Moscow, Zh-35, Raushsk nab., d. 4/5

Production and printing company, Uzhgorod, st. 1 project, 4

W

15

0

five

0

a boscopic sweep of a universal oscilloscope, for example, C1-10, and the processing unit 5 can be implemented as a functional converter that performs the specified algorithm or is based on a microcomputer.

Claims (1)

Invention Formula A sound speed meter containing a generator and a radiating transducer connected to it, a receiving transducer interconnected by a counter and a processing unit, as well as a crystal oscillator, which is often so that, in order to improve accuracy, it is equipped with a temporary block conversion, made in the form of serially connected frequency divider, delay line, time expander and comparator, the input of the frequency divider and the second input of the delay line are connected to the output of the crystal oscillator, the output of the frequency divider You are connected to the generator input, the comparator output is connected to the second input of the time expander, the counter input and the input of the processing unit, the output of the receiving converter is connected to the third input of the time expander, the output of the delay line is connected to the second input of the counter.