CN2233571Y

CN2233571Y - Echoing acoustic velocity measuring instrument

Info

Publication number: CN2233571Y
Application number: CN 95243381
Authority: CN
Inventors: 刘镇清
Original assignee: Tongji University
Current assignee: Tongji University
Priority date: 1995-01-23
Filing date: 1995-01-23
Publication date: 1996-08-21
Anticipated expiration: 2005-01-23

Abstract

The utility model relates to an echo acoustic speed measuring instrument, which is composed of a casing, a main control vibrator, a transmitting circuit, an ultrasonic transducer, a receiving amplifier, an echo detector, a counting time base pulse generator, a gate circuit, a frequency divider, a number accumulating counter and a numerical code display. The dithering of the vibration period of the main control vibrator is adopted to eliminate the correlation between the output square wave of the echo detector and the counting time base pulse, which causes the progressive mean of the number accumulating counter to have significance and increases the measuring accuracy. The utility model is a single and integral instrument which is suitable for measuring the acoustic speed in gas, liquid and solid, and the utility model has the characteristics of simple structure, portability, convenient use, high measuring accuracy, etc.

Description

A kind of echo is to the echo type sound velocimeter

The utility model relates to measures the apparatus that the velocity of sound is used

The acoustic velocity measutement device that occasional combinations such as one receiver, commercial counting instrument and oscillograph become can take place by means of audiogage or by ultrasound wave in acoustic velocity measutement at present.Supersonic thickness meter is a kind of instrument that independently adopts pulse echo method to constitute, have advantage simple in structure, easy to use, but the measuring accuracy of this instrument is subjected to the restriction of its inner count frequency, the error that has ± 1 count value, and can only survey the solid velocity of sound by this instrument.And the acoustic velocity measutement device that is combined into commercial counting instrument etc., has the velocity of sound that to survey solid, liquid, three kinds of media of gas, but its measuring accuracy is subjected to the restriction of commercial counting instrument, in order to reach high-acruracy survey, must the expensive commercialization of configuration count instrument, and, made troubles to carrying, using because of interim overlap joint combination before use.

The purpose of this utility model provides a kind of pulse echo method sound velocimeter of independent completion, it adopts the ultrasonic pulse extracting mode of echo to echo, and further purpose provides the sound velocimeter that a kind of high precision low price that does not rely on commercial counting instrument can be surveyed three kinds of media of solid, liquid, gas.

The utility model is to comprise housing, master oscillator, radiating circuit, reception amplifier, echo detecting device, main pulse generator during counting, gate circuit, frequency divider, digital summary counter, the acoustic velocity measutement device of nixie display and ultrasonic transducer.Its structural feature is, master oscillator is arranged in the housing, its output respectively with radiating circuit, each input of frequency divider and echo detecting device is connected, wherein master oscillator and the correlativity that can eliminate being connected of echo detecting device between detection of echoes and when counting main pulse, improve accuracy of detection with this, the output of radiating circuit is connected with an end of housing ultrasonic transducer outward, the other end of ultrasonic transducer back in the housing with housing in reception amplifier, the echo detecting device, gate circuit is connected successively and is formed the circuit of an echo to echo, another input of gate circuit links to each other with the output of when counting main pulse generator, its output links to each other with the input of digital summary counter, another input of summary counter is connected with frequency divider output, its output is connected with the nixie display input, this device has been realized and the different counting at random of existing commercial counting instrument, the arithmetic mean function, reduced the error that the counting quantification brings, in addition, change the kind of ultrasonic transducer, promptly can be used for measuring solid, liquid, the velocity of sound of three kinds of media of gas.

Characteristics of the present utility model are:

1. not external commercial counter of this device or oscillograph descend installation cost greatly, and except that ultrasonic transducer, remainder is assembled in the housing, and volume dwindles greatly.

2. adopted a kind of easy echo to echo technique, made acoustic velocity measutement not be subjected to the influence of time-delays such as circuit, cable.

3. utilize the frequency drift characteristic of master oscillator to realize that counting averaging at random improves the counting accuracy, greatly reduce the restriction of counting quantization error paired pulses echo counting method acoustic velocity measutement precision.

4. select the different types of ultrasonic transducer of solid, liquid, gas, this device can be surveyed the velocity of sound of solid, liquid, gas.

Description of drawings:

Fig. 1 is a structural principle block diagram of the present utility model

The sequential chart that Fig. 2 detects to echo for the utility model echo

Fig. 3 is the enforcement figure of master oscillator circuit

Fig. 4 is the enforcement figure of ultrasonic echo detector circuit

Fig. 5 is the sequential chart of ultrasonic echo detector circuit

Fig. 6 is the enforcement figure of digital summary counter circuit

Be described with reference to the accompanying drawings design of the present utility model, concrete structure and enforcement.

Fig. 1 is a structural principle block diagram of the present utility model.Master oscillator 1 in the housing 11 links to each other with the input of radiating circuit 2, echo detecting device 5, frequency divider 8 respectively, the output of radiating circuit 2 is connected with ultrasonic transducer 3 one ends of housing 11 outsides, its other end taps in the housing 11 and with reception amplifier 4 and links to each other, the other end of reception amplifier 4 links to each other with echo detecting device 5, gate circuit 7 respectively with when counting main pulse generator 6, echo testing circuit 5 and summary counter 9 be connected, the other two ends of counter 9 are connected with frequency divider 8, nixie display 10 respectively.Except that ultrasonic transducer 3, all parts constitute instrument part of the present utility model, and partly with a housing 11 encapsulation, 3 of ultrasonic transducers pass through common high frequency cable and partly link to each other with instrument instrument.

The sequential chart that Fig. 2 detects to echo for the utility model echo.The 1 generation cycle of master oscillator is that the continuous square wave of T (is seen Fig. 2 a), this square wave send radiating circuit 2, frequency divider 8 and echo detecting device 5, under the excitation of this square wave rising edge, radiating circuit 2 produces a very narrow potential pulse, this pulse action is on

ultrasonic transducer

3,3 of transducers are launched ultrasound wave (seeing Fig. 2 b), and this ultrasound wave is propagated in medium and produced reflection echo when running into reflecting surface.Reflection echo arrives transducer 3 back part energy and is converted into the correspondent voltage signal and is received by reception amplifier 4, and another part energy returns medium again, causes repeatedly reflection thus, form echo I, echo II, echo III ... (seeing Fig. 2 b).It is 10V that reception amplifier 4 is amplified to peak-to-peak value with preceding twice echoed signal, and waveform is saturated magnifying state, and this echo can be enough to trigger common TTL circuit, detects required echoed signal for echo detecting device 5.When arriving, the square wave rising edge that echo detecting device 5 sends at master oscillator 1 starts working, and when arriving, echo I make the output of echo detecting device 5 uprise level, low level (seeing Fig. 2 c) was got back in output when echo II arrived, and the width of the square-wave signal of echo detecting device 5 outputs is promptly represented the time of echo I to echo II like this.With echo detecting device 5 output with the time main pulse counter 6 (waveform is seen Fig. 2 d) send into two input ends of AND circuit 7 respectively, the time 6 of main pulses in the square wave high level of echo detecting device 5, count shown in Fig. 2 e waveform.According to the cycle δ of time base count pulse 6, if the counting number of Fig. 2 e is N, then can to produce echo I be N δ ± δ to the time value of echo II to the single counting, it has ± and the error of 1 count word.The frequency division value M of frequency divider 8 is the number of times of the stored count of counter 9; The nixie display 10 final values that show are M the numerical value behind the counting, and display sensitivity is δ/M like this, and the standard deviation of measurement is

If the time value that provides at last of nixie display 10 is t, then according to ultrasound wave in medium, propagate apart from l, can be regarded as out velocity of sound c=l/t.

Meaningful in order to reach the counting progressive mean, measuring accuracy is increased, should guarantee between the output signal of time of occurrence main pulse generator 6 when counting of output square wave (seeing Fig. 2 c) of echo detecting device 5 uncorrelated mutually, separate.For accomplishing this point, main pulse produces the circuit of randomized jitter in the time of also can adopting the counting in the commercial counting instrument, but do not only uneconomical like this but when making counting the main pulse circuit become complicated, so adopting, the utility model has randomized jitter the oscillation period of master oscillator 1, correlativity when the time of occurrence of determining under the condition to be driven by its echo detecting device 5 output square waves in the transonic time produces input square wave that randomized jitter eliminates echo detecting device 5 and counts between the main pulse, so also can make accumulated counts on average meaningful, it is simple that the counting averaging circuit that the utility model is used is counted the circuit that uses in the instrument than commercialization.

Fig. 3 is the embodiment of master oscillator, the oscillator that it is made up of not

gate

12,13,14 and resistance 15, electric capacity 16.The input of not gate 12 is from the output of not gate 14, one end of the output connecting resistance 15 of not gate 13, the input of another termination not gate 14 of resistance 15, the input of not gate 13 is from the output of not gate 12, the two ends of electric capacity 16 connect the output of not gate 12 and the input of not gate 14 respectively, and the output of not gate 14 is as the output of controlled oscillator.The utility model utilizes the unsettled characteristics of master oscillator 1 output square-wave cycle, realizes the purpose of above-mentioned counting at random.As long as main pulse cycle δ can make accumulated counts on average meaningful during the time-amplitude that makes this randomized jitter counting that the main pulse generator produces during greater than counting, the square-wave cycle randomized jitter that master oscillator 1 produces in this device is easy to make accumulated counts on average to reach the effect of reduction quantization error.

Fig. 4 and Fig. 5 are respectively the sequential of the enforcement figure and the echo detecting device 5 of echo detecting device 5.The B input end of the signal order steady 17 that master oscillator 1 takes place, when arriving, master oscillator 1 rising edge (sees Fig. 5 a), trigger monostable 17 actions and produce a pulse (seeing Fig. 5 c), make pulse (Fig. 5 c) width of monostable 17 outputs get final product (preventing trigger 19 false triggerings) greater than the hyperacoustic repercussions of emission.The negative pulses of monostable 17 output Q ends are delivered to the clear terminal (CLR) of trigger 19, and at this moment the output Q of trigger 19 end is low level.The echoed signal (seeing Fig. 5 b) that process reception amplifier 4 amplifies is connected to the CK end of trigger 19, and trigger 19 overturns (to see Fig. 5 b) when echo I arrives, and output Q holds and becomes high level (seeing Fig. 5 d).The Q of trigger 19 output delivered to monostable 18 B input, monostable 18 (when echo 1 arrives) output one pulses (seeing Fig. 5 e) when the rising edge arrival of signal takes place trigger 19 make this pulse width get final product (preventing the false triggering of trigger 20) greater than the width of echo 1.The negative pulses of monostable 18 output Q are delivered to the clear terminal (CLR) of trigger 20, and 20 on trigger output terminal Q when reset signal arrives is changed to low level (Fig. 5 f).The CK that echoed signal (Fig. 5 b) is delivered to trigger 20 holds, trigger 20 upsets when the echo II shown in Fig. 4 b arrives.Therefore the Q of trigger 20 output is shown in Fig. 5 f, its positive level square width is the time of echo I to echo II, the Q output of trigger 20 is linked to each other with an input end of gate circuit 7, the other end signal of gate circuit 7 is from when counting main pulse count generator 6, and the count value exported of gate circuit 7 is the count value of single echo I to the echo II time like this.

Fig. 6 is the enforcement figure of the utility model summary counter 9.The count pulse input A of counter 26 is from the output of gate circuit among Fig. 47.The input B of the monostable trigger 21 in the frequency divider 8 output map interlinkings 6, burst pulse of monostable trigger 21 outputs when the rising edge of frequency dividing circuit 8 outputs arrives like this.The end of energizing (latching end) of monostable trigger 21 output Q termination impact dampers 24 and impact damper 25, the delay circuit that monostable trigger 21 output Q ends are formed by resistance 22 and electric capacity 23 is connected with the clear terminal of counter 26 sum counters 27.When sending a pulse, monostable trigger 21 at first deposits the count value data of counter 26 and counter 27 in impact damper 24 and impact damper 25 like this, thereafter with after counter 26 and counter 27 zero clearings, and counting again again when the counting input arrives.Monostable trigger 17 output pulse widths are similar among the pulse width of monostable trigger 21 outputs and Fig. 4.The most significant digit Q of counter 26 _hExport to another 8 digit counter 27 again, form 16 accumulated counts with this.8 digit buffers 24 and 8 digit buffers 25 are sent in the output of 8 digit counters 26 and 8 digit counters 27 respectively, because the divider ratio M of frequency divider 8 is the cumulative number of summary counter, the output signal of frequency divider rising edge arrives when accumulated counts reaches M like this, it at first deposits the accumulated counts value in impact damper by monostable 21, thereafter to counter 26, counter 27 zero clearings, carry out next M accumulated counts process again.The output of impact damper 24, impact damper 25 then shows the result of accumulated counts for the nixie display among Fig. 1 10.

Radiating circuit 2 in the utility model is identical with the radiating circuit of common ultrasonic measurement instrument, 4 of reception amplifiers are common broad band amplifier, ultrasonic transducer 3 optional gases, liquid, solid ultrasonic transducer, main pulse generator 6 also can be realized by common crystal oscillating circuit during counting, frequency divider 8 is made up of the TTL digital circuit, and the digital device that shows also is that conventional a plurality of seven-segment numeric indicators and interlock circuit formed.

Claims

1. an echo is to the echo type sound velocimeter, by master oscillator (1), radiating circuit (2), reception amplifier (4), echo detecting device (5), main pulse generator (6) during counting, gate circuit (7), frequency divider (8), numeral summary counter (9), nixie display (10), ultrasonic transducer (3) and housing (11) are formed, it is characterized in that, in housing (11), output elder generation and radiating circuit (2) with master oscillator (1), the input of frequency divider (8) is connected, the output connecting line of radiating circuit (2) leads to outside the housing (11), be connected with an end of the ultrasonic transducer (3) of housing (11) outside, the input that the other end connecting line of ultrasonic transducer (3) enters the reception amplifier (4) in housing (11) and the housing (11) links to each other, the output of reception amplifier (4) links to each other with an input of echo detecting device (5), echo detecting device (5) is connected with two inputs of the output AND circuit (7) of when counting main pulse generator (6), and the output while of gate circuit (7) and frequency divider (8) is connected with the input of digital summary counter (9), and the output of digital summary counter (9) links to each other with nixie display (10); The output of master oscillator (1) also directly links to each other with another input of echo detecting device (5), the correlativity when eliminating detection of echoes and counting by this between the main pulse.

2. according to the sound velocimeter of claim 1, it is characterized in that replacing ultrasonic transducer (3) can be fit to measure the velocity of sound in the gas, liquid, solid body.