CN103389153B - Ultrasonic wave transit time measuring circuit by secondary reflection waves - Google Patents
Ultrasonic wave transit time measuring circuit by secondary reflection waves Download PDFInfo
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- CN103389153B CN103389153B CN201310333614.7A CN201310333614A CN103389153B CN 103389153 B CN103389153 B CN 103389153B CN 201310333614 A CN201310333614 A CN 201310333614A CN 103389153 B CN103389153 B CN 103389153B
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Abstract
The invention relates to an ultrasonic wave transit time measuring circuit by secondary reflection waves. The ultrasonic wave transit time measuring circuit is used on an ultrasonic flowmeter and used for measuring the ultrasonic wave transit time between two sensors through the waveform similarity between primary received ultrasonic waves and secondary reflected ultrasonic waves. The ultrasonic wave transit time measuring circuit comprises a multi-path gating device (5), a programmable amplifier (6), waveform characteristic judging electrical systems (7-13), wherein the multi-path gating device (5) is used for ensuring that excitation signals, the primary received signals and the secondary reflected waves can accurately enter a subsequent circuit; the programmable amplifier (6) is used for processing different magnification time requirements of the primary received signals and the secondary reflected signals; the waveform characteristic judging electrical systems (7-13) are used for controlling the starting up/shutting down of a time counter (14) according to judgment results so as to complete the measurement of the transit time. According to the ultrasonic wave transit time measuring circuit, the energy source of the primary received ultrasonic waves is the same as that of the secondary reflected ultrasonic waves, so that a super-high similarity relation exists between the primary received ultrasonic waves and the secondary reflected ultrasonic waves. Thus, the problem that corresponding waveform characteristics are misjudged is avoided.
Description
Technical field
The present invention relates to a kind of circuit utilizing secondary reflection wave measurement ultrasonic time of flight, be mainly used in transit-time ultrasonic flow meter, to the measurement of sound wave transit time between two subtend ultrasonic sensors.
Background technology
Transit-time ultrasonic flow meter relies on and detects flow media to the modulating action of ultrasonic signal, obtains the transit time of sound wave in regular length sound channel, thus extrapolates the flow speed data of medium.Current ultrasonic low to be taked the specific markers point identification of waveform, to judge the transit time, therefore just to have become the gordian technique of transit-time ultrasonic flow meter to the judgement of specific markers point on waveform usually.
In prior art, when sending ultrasonic signal, the main method taked comprises:
1, adopt square wave train excitation, and threshold value is set, after signal replication exceedes threshold value, adopt the zero crossing position of several waveforms thereafter as feature locations.This method is applied in gas time difference type flowmeter exists certain difficulty, when flow stability is poor, may there is certain variation in different time sections in its amplitude, causes threshold value cannot navigate on same waveform, thus there is judging by accident across the cycle of unique point, as shown in Figure 2 and Figure 4.
2, adopt the excitation of coded system, and detect the frequency change situation received in waveform, by determining waveform character point with encouraging the corresponding relation of encoding, as shown in Figure 3 and Figure 5.This mode uses more on radar, but use has some problems on ultrasonic sensor.Ultrasonic sensor can obtain best output situation on its resonant frequency point, but adopts coded excitation just inevitably to need to depart from its resonance frequency.Ultrasonic sensor is when being less than resonant frequency, and electric current leading voltage embodies capacitive, and when being greater than resonant frequency, circuit embodies perception.There is desirable encoding efficiency by being difficult in the waveform received in real work, and there is obvious transition frequency composition in waveform, and unique point is also very easy to occur that the cycle judges by accident.
Summary of the invention
The object of the invention is, solve in prior art and the problem that fault rate is comparatively large and algorithm is complicated is judged to ultrasound wave zero crossing, utilize the waveform height similarity having cause-effect relationship once to receive ripple and secondary counter ejected wave to judge the transit time.Its concrete technical scheme is as follows:
A kind of circuit utilizing secondary reflection wave measurement ultrasonic time of flight, be used in the primary instrument being made up of flowmeter flowmeter shell and ultrasonic sensor, comprise: excitation signal generator, produce squared pulse trains, by multi-channel gating device for encouraging ultrasonic sensor or ultrasonic sensor; Then successively the once secondary counter ejected wave received on ripple and another ultrasonic sensor on ultrasonic sensor is introduced follow-up programmable amplifier by multi-channel gating device; First peak detctor measures and keeps the highest amplitude of whole wave sequence; Second peak detctor passes through zero-acrross ing moment and output can be reset on each waveform, therefore obtains the highest amplitude of single waveform; After the peak value of wave sequence crosses peak, first peak detctor will be no longer identical with the output of the second peak detctor, if the voltage difference that differential amplifier records both exceedes permissible value, Second Threshold comparer is by output and keep an open window signal S7, under signal S7 controls, thereafter first passes over zero signal and put into follow-up time counting unit, the width producing a square-wave signal S8, square-wave signal S8 is the transit time of two waveform character pair points.
Further, signal S2 is the threshold voltage controlled by flowmeter processor, and arrange first threshold comparer, signal amplitude just can use two peak detctors after exceeding threshold voltage.
Further, falling edge detectors and negative edge detecting device are set, respectively produce on pass over zero signal S3 and under pass over zero signal S4.
The beneficial effect of patent of the present invention is: make use of the similarity once receiving ripple and secondary counter ejected wave and carry out work, evaded the problem in other technologies, zero crossing position easily being occurred to erroneous judgement.And transit time data are directed to the zero crossing position of signal itself, without any additional calculating and derivation, result has good accuracy.
Accompanying drawing explanation
Fig. 1 is circuit of the present invention composition structural representation;
Fig. 2 is the schematic diagram of the square wave sequence de-energisation sensor utilizing fixed frequency in prior art;
Fig. 3 is the schematic diagram of the square wave sequence de-energisation sensor utilizing frequency coding in prior art;
Fig. 4 is the schematic diagram utilizing single threshold method to judge waveform character point in prior art;
Fig. 5 is the schematic diagram utilizing the frequency change in waveform to judge waveform character point in prior art;
Fig. 6 is pumping signal and secondary counter ejected wave A, once receive ripple B, comparison of wave shape schematic diagram that secondary counter ejected wave amplifies C;
The signal characteristic schematic diagram of each key position in each circuit of Fig. 7;
In figure, each Reference numeral implication is: 1-flowmeter shell, 2,3-ultrasonic sensor, 4-excitation signal generator 5-multi-channel gating device, 6-programmable amplifier, 7-first threshold comparer, 8-falling edge detectors, 9-negative edge detecting device, 10-first peak detctor, 11-second peak detctor, 12-differential amplifier, 13-Second Threshold comparer, 14-time counter.
Embodiment
Below in conjunction with accompanying drawing, the invention will be further described.
The present invention utilizes the causal waveform once receiving ripple and secondary counter ejected wave, using to the judgement reference point of amplitude peak as both, openly judges window, and passes over zero position as comparison position, the calculating transit time using on waveform thereafter.In order to realize above logical relation, be provided with in Circuits System: the first peak detctor 10 measures the highest amplitude of whole wave sequence; Second peak detctor 11 passes through zero-acrross ing moment and resets output on each waveform, thus obtains the highest amplitude of single waveform.After peak value crosses peak, both compare and export as window signal, detect and thereafter immediately first pass over zero signal, control clock start and stop, reach measurement object.Falling edge detectors 8, negative edge detecting device 9 provide upper and lower crossover point signal for giving other parts of circuit.
As shown in Figure 1, the circuit of secondary reflection wave measurement ultrasonic time of flight that utilizes of the present invention is used in the primary instrument being made up of flowmeter flowmeter shell 1 and ultrasonic sensor 2,3; Circuit part comprises: excitation signal generator 4, produce squared pulse trains, here 2 are assumed to be for encouraging ultrasonic sensor 2 or 3() by multi-channel gating device 5, then successively the once secondary counter ejected wave received on ripple and ultrasonic sensor 2 on ultrasonic sensor 3 is introduced follow-up programmable amplifier 6 by multi-channel gating device 5, programmable amplifier 6 exports as signal S1 enters subsequent processes.The signal waveform of each key component as shown in Figure 7.
Signal S2 is the threshold voltage controlled by flowmeter processor, and arrange first threshold comparer 7, signal amplitude just can use two peak detctors 10 and 11 after exceeding threshold voltage.
In circuit, the null position that passes over up and down of waveform is all important judgement key element, is therefore provided with falling edge detectors 8 and negative edge detecting device 9 in circuit, respectively produce on pass over zero signal S3 and under pass over zero signal S4.
First peak detctor 10 measures and keeps the highest amplitude of whole wave sequence, until have extraneous reset indication, as S5; Second peak detctor 11 passes through zero-acrross ing moment and output can be reset on each waveform, therefore can only obtain the highest amplitude of single waveform, as S6.After the peak value of wave sequence crosses peak, first peak detctor 10 will be no longer identical with the output of both the second peak detctors 11, if the voltage difference that differential amplifier 12 records both exceedes permissible value, Second Threshold comparer 13 is by output and keep an open window signal S7.Under signal S7 controls, thereafter first passes over zero signal and put into follow-up time counting unit 14, the width producing a square-wave signal S8, S8 is the transit time of two waveform character pair points.
The present invention uses once reception ripple and secondary counter ejected wave to judge, during flow meters work, first pumping signal is sent, after being delivered to subtend sensor, subtend sensor can collect a waveform (once receiving ripple), and a waveform can be reflected on former stimulus sensor simultaneously, the waveform that now former stimulus sensor will receive is exactly secondary counter ejected wave, the invention has the advantages that once reception ripple and secondary counter ejected wave have very directly cause-effect relationship (being all produced by the mechanical wave of homology) on energy, through amplification after once reception ripple and secondary counter ejected wave similarity very large, as shown in Figure 6.Therefore circuit of the present invention work have better original signal basis with unique point differentiate stability.
The once reception ripple that circuit of the present invention utilizes two similarity degrees high in the course of the work and second trip echo compare, and can effectively avoid in prior art at square wave sequence and the corresponding Problem-Error found corresponding relation in sine wave sequence and may exist.
Claims (3)
1. one kind utilizes the circuit of secondary reflection wave measurement ultrasonic time of flight, be used in the primary instrument being made up of flowmeter flowmeter shell (1) and ultrasonic sensor (2,3), comprise: excitation signal generator (4), produce squared pulse trains, by multi-channel gating device (5) for encouraging the first ultrasonic sensor (2) or the second ultrasonic sensor (3); Then successively the secondary counter ejected wave on another ultrasonic sensor (2,3) in the once reception ripple on the described first or second ultrasonic sensor (2,3) and the first or second ultrasonic sensor (2,3) is introduced follow-up programmable amplifier (6) by multi-channel gating device (5); First peak detctor (10) measures and keeps the highest amplitude of whole wave sequence; Second peak detctor (11) passes through zero-acrross ing moment and output can be reset on each waveform, therefore obtains the highest amplitude of single waveform; After the peak value of wave sequence crosses peak, first peak detctor (10) will be no longer identical with the second peak detctor (11) both output, if the voltage difference that differential amplifier (12) records both exceedes permissible value, Second Threshold comparer (13) is by output and keep an open window signal S7, under signal S7 controls, thereafter first passes over zero signal and put into follow-up time counting unit (14), the width producing a square-wave signal S8, square-wave signal S8 is the transit time of two waveform character pair points.
2. utilize the circuit of secondary reflection wave measurement ultrasonic time of flight as claimed in claim 1, it is characterized in that: signal S2 is the threshold voltage controlled by flowmeter processor, arrange first threshold comparer (7), signal amplitude just can use two peak detctors (10,11) after exceeding threshold voltage.
3. utilize the circuit of secondary reflection wave measurement ultrasonic time of flight as claimed in claim 1, it is characterized in that: falling edge detectors (8) and negative edge detecting device (9) are set, respectively produce on pass over zero signal S3 and under pass over zero signal S4.
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| CN201310333614.7A CN103389153B (en) | 2013-08-02 | 2013-08-02 | Ultrasonic wave transit time measuring circuit by secondary reflection waves |
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| CN201310333614.7A CN103389153B (en) | 2013-08-02 | 2013-08-02 | Ultrasonic wave transit time measuring circuit by secondary reflection waves |
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| CN103630174B (en) * | 2013-12-07 | 2016-04-13 | 重庆前卫科技集团有限公司 | A kind of flow-measuring method of ultrasonic flow meter |
| CN104332940B (en) * | 2014-11-19 | 2017-10-17 | 阳光电源股份有限公司 | Suppress method, device and the micro-grid system of capture erroneous judgement |
| CN109612541B (en) * | 2018-12-07 | 2020-06-26 | 天津商业大学 | Mistake wave prevention signal processing circuit of gas ultrasonic flowmeter |
| CN111044110A (en) * | 2019-12-19 | 2020-04-21 | 河北工业大学 | Gas ultrasonic flowmeter signal processing method based on similarity analysis |
| CN113126110A (en) * | 2021-06-16 | 2021-07-16 | 北京星天科技有限公司 | Device and method for detecting arrival time of acoustic echo |
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| US4787252A (en) * | 1987-09-30 | 1988-11-29 | Panametrics, Inc. | Differential correlation analyzer |
| AU2003280620A1 (en) * | 2002-11-26 | 2004-06-18 | Matsushita Electric Industrial Co., Ltd. | Ultrasonic flowmeter and ultrasonic flow rate measuring method |
| JP4572546B2 (en) * | 2004-03-10 | 2010-11-04 | パナソニック株式会社 | Fluid flow measuring device |
| CN101162164A (en) * | 2007-11-16 | 2008-04-16 | 浙江理工大学 | Frequency modulation wave marking method for time-difference process ultrasonic flowmeter |
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