CN107478282A - Ultrasonic flow rate detection signal processing method and processing device, time difference method ultrasonic testing system - Google Patents
Ultrasonic flow rate detection signal processing method and processing device, time difference method ultrasonic testing system Download PDFInfo
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- CN107478282A CN107478282A CN201710706720.3A CN201710706720A CN107478282A CN 107478282 A CN107478282 A CN 107478282A CN 201710706720 A CN201710706720 A CN 201710706720A CN 107478282 A CN107478282 A CN 107478282A
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- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
- G01F1/66—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by measuring frequency, phase shift or propagation time of electromagnetic or other waves, e.g. using ultrasonic flowmeters
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Abstract
The invention belongs to field of signal processing, discloses a kind of ultrasonic flow rate detection signal processing method and processing device, time difference method ultrasonic testing system, and coupled signal is amplified using same tranmitting frequency consistent bandpass amplifier and eliminates most of out-of-band noise；Automatic gain amplification is carried out to the coupled signal of band logical output, makes the stable peak-to-peak value set in chip of output amplitude of the coupled signal after carry out automatic growth control；Suitable reference voltage is selected, the coupled signal after progress automatic growth control is converted into square-wave signal；Obtain the upper fall time of square-wave signal, ask for the average of the upper fall time of square-wave signal, the sampling period time to peak of coupled signal is obtained, flow rate calculation is carried out based on parameters such as following current, the same sampling period time to peak of the coupled signal of adverse current and the pipe diameters that pre-sets.The present invention is advantageous to adapt to coupled signal changes in amplitude, it is had well adapting to property in liquid/gas body flow detection.
Description
Technical field
The invention belongs to field of signal processing, more particularly to a kind of ultrasonic flow rate detection signal processing method and processing device, when
Poor method ultrasonic testing system.
Background technology
Usually unstable due to detecting obtained coupled signal in existing time difference method ultrasonic testing system, it couples amplitude
It is sometimes big, it is sometimes small, no matter by the amplifier of fixed multiplication factor, or the adjustable method of multiplication factor, be all difficult
The transient change of coupled signal is adapted to, automatic increasing can be made full use of by way of being amplified to fixed peak-to-peak value (such as 2V)
The automatic regulation function of beneficial amplification chip, and avoid the complexity and hysteresis quality of software adjustment, so as to simplify the software of system
Processing procedure；In existing time difference ultrasonic amount detection process, the detection of generally use zero-crossing timing point, unilateral detected along time point
The positive/negative to the flight time of ultrasonic echo is obtained etc. mode, and these detection methods are under the conditions of coupled signal changes in amplitude
Preferable stability is difficult to ensure that, existing technology is：(1) coupled signal is put using the amplifier of fixed multiplication factor
Greatly, forward and reverse propagation time difference of ultrasound is then obtained；(2) amplitude of the ultrasonic coupling signal obtained using detection, to amplification
Device is amplified multiple modulation, and so as to adapt to the changes in amplitude of ultrasonic signal, but this method has degree coupled signal processing
Hysteresis quality.
In summary, the problem of prior art is present be：In existing time difference method ultrasonic testing system, because coupled signal is normal
It is often unstable, its couple it is big during amplitude, when it is small, it is no matter adjustable by the amplifier of fixed multiplication factor, or multiplication factor
Method, all it is difficult the transient change for adapting to coupled signal；In existing time difference ultrasonic amount detection process, the inspection of generally use zero passage
The modes such as survey, single Edge check obtain the flight time of ultrasonic echo, and these detection methods are in coupled signal changes in amplitude
Under the conditions of be difficult to ensure that preferable stability；And, it is necessary to consider echo-signal in existing time difference ultrasonic amount detection technique
Size, in AGC (automatic gain amplification) chip amplification range, use AGC (automatic gain amplification) chips or its
The output signal of automatic enlarging function and the peak-to-peak value (such as 2V) being fixed；It can not be caused to be examined in liquid, gas flow
There is well adapting to property, so as to cause the time difference signal that can not be stablized under conditions of coupled signal changes in amplitude in survey
And testing result.
The content of the invention
The problem of existing for prior art, the invention provides a kind of ultrasonic flow rate detection signal processing method and dress
Put, time difference method ultrasonic testing system, the time difference signal that can be stablized under conditions of coupled signal changes in amplitude and detection
As a result.
The ultrasonic flow rate detection signal processing method that the present invention realizes, including：
Coupled signal is amplified using same tranmitting frequency consistent bandpass amplifier and eliminates most of out-of-band noise；
Automatic gain amplification is carried out to the coupled signal of band logical output, makes the coupled signal after carry out automatic gain amplification
The stable peak-to-peak value set in chip of output amplitude；
Suitable reference voltage is selected, the coupled signal after progress automatic gain amplification is converted into square-wave signal；
The upper fall time of square-wave signal is obtained, the average of the upper fall time of square-wave signal is asked for, obtains coupled signal
Sampling period time to peak, based on following current, the coupled signal of adverse current same sampling period time to peak and pre-set
The parameter such as pipe diameter carry out flow rate calculation.
It is preferred that the signal amplitude of the coupled signal after the baseband processing is corresponding to the progress automatic gain amplification
The signal amplitude input range of automatic gain controller is interior and is amplified effective adjust automatically of multiple.
It is preferred that the reference voltage range is arranged on a cycle of the coupled signal after carrying out automatic gain amplification
Crest voltage and second period crest voltage between.
It is preferred that the reference voltage is the crest voltage of a cycle and the peak value electricity of the second period
Press the average value of sum.
Another object of the present invention is to provide a kind of ultrasonic flow rate detection signal processing unit, the ultrasonic flow rate detection
Signal processing apparatus includes：Bandpass amplifier, automatic gain controller, voltage comparator, high precision time measurement chip and stream
Calculator is measured, wherein,
Bandpass amplifier, it is consistent with tranmitting frequency, for coupled signal being fixed multiplication factor and baseband processing；
Automatic gain controller, for carrying out automatic growth control to the coupled signal after baseband processing, so as to carry out certainly
The signal output amplitude stabilization of coupled signal after dynamic gain control is in the peak-to-peak value pre-set；
Voltage comparator, for according to the reference voltage obtained, the coupled signal after progress automatic growth control to be changed
For square-wave signal；
High precision time measurement chip, the up/down for detection comparator output square-wave signal are follow-up along time point
It is positive/negative to provide high-precision time basis to time to peak；
Airflow calculator, the positive/negative sampling period peak value to propagation of coupled signal is calculated along time point by up/down
Time, and carried out according to parameters such as following current, the cycle peak time of the coupled signal of adverse current and the pipe diameters that pre-sets
Flow detection..
The signal transacting scheme of the present invention has for the changes in amplitude of coupled signal in time difference ultrasonic amount detection process
There is stronger adaptability, meanwhile, on the basis of the coupled signal processing of this method, the acquisition of temporal information and processing method have
Preferable stability, the invention are taken into consideration in terms of hardware and software processing two, can largely improve time difference method ultrasound
The resistance to overturning of flow quantity detecting system and the adaptability to coupled signal.Multiplication factor is adjusted with respect to software processing
Mode, method of the invention do not have to consider echo-signal size, as long as in AGC (automatic gain amplification) chip amplification range
It is interior, the output signal for the peak-to-peak value 2V that can be fixed so that it has preferable in liquid, detection of gas flow rate
Adaptability.
The present invention can improve the stability in time difference measurement data；Ultrasonic coupling signal is in different situations (pressure, temperature
The conditions such as degree, flow velocity) under, the amplitude of coupled signal has certain change, samples fixed multiplication factor or directly setting is compared
Point obtains the mode of flight time, can be different due to the intensity of signal, and causes the difference at time point, so that measurement is stable
Property reduce；The present invention can preferably ensure the stability of signal output amplitude under conditions of AGC functions；Exported stable
Under conditions of amplitude, the time point for having comparison point to obtain also can guarantee that higher stability.
Brief description of the drawings
Fig. 1 is ultrasonic flow rate detection signal process flow figure provided in an embodiment of the present invention.
Fig. 2 is transit time ultrasonic flow meters measuring principle figure provided in an embodiment of the present invention.
Fig. 3 is ultrasonic flow rate detection signal processing method implementation process figure provided in an embodiment of the present invention.
Fig. 4 is the ultrasonic coupling signal graph provided in an embodiment of the present invention with noise.
Fig. 5 is the signal graph after band logical amplification provided in an embodiment of the present invention.
Fig. 6 is AGC amplifying circuit output signals figure provided in an embodiment of the present invention.
Fig. 7 is fixed voltage comparator output square wave figure provided in an embodiment of the present invention.
Fig. 8 is upper lower edge provided in an embodiment of the present invention and peak detection process figure.
Embodiment
In order to make the purpose , technical scheme and advantage of the present invention be clearer, with reference to embodiments, to the present invention
It is further elaborated.It should be appreciated that the specific embodiments described herein are merely illustrative of the present invention, it is not used to
Limit the present invention.
The time difference ultrasonic detection of the present invention, is by measuring with ultrasonic propagation velocity and the adverse current changed and following current
Time difference △ t determine the ultrasonic flowmeter of the flow velocity of detected fluid, time difference △ t and flow velocity are proportional, its ratio
Coefficient claims flow modificatory coefficient.
Below in conjunction with the accompanying drawings and specific embodiment is further described to the application principle of the present invention.
As shown in figure 1, ultrasonic flow rate detection signal processing method provided in an embodiment of the present invention, including：
S101：Coupled signal is fixed multiplication factor and band logical using same tranmitting frequency consistent bandpass amplifier
Processing；
In this step, the processing of coupled signal is carried out, that is, uses the consistent bandpass amplifier of same tranmitting frequency, coupling is believed
Number the signal enhanced processing of multiplication factor and the baseband processing of frequency is fixed, to eliminate various noises pair in coupled signal
The influence of detection, and make the signal amplitude from bandpass amplifier output in AGC signal amplitude input ranges so that output signal
Meet requirements of the AGC to applied signal voltage amplitude range.
S102：Automatic growth control is carried out to the coupled signal after baseband processing, so that after carrying out automatic growth control
The fixation peak-to-peak value that the signal output amplitude stabilization of coupled signal is set in chip；
In this step, automatic growth control processing is carried out to the coupled signal after baseband processing, can improve and coupling is believed
The adaptability of number changes in amplitude, the multiplication factor of the coupled signal after being handled using AGC adjust automaticallies band logical, so as to pass through AGC
The output amplitude of coupled signal after adjustment stablizes the signal in a default peak-to-peak value, making input AGC, i.e., after baseband processing
Coupled signal in the case of changes in amplitude, using the automatic regulation function of AGC chips, stable amplitude (electricity can be exported
Pressure), so as to realize the signal output of fixed peak-to-peak value so that in subsequent treatment, the reference voltage selection of comparator has preferably
Stability, will not accordingly be changed with the changes in amplitude of the coupled signal after baseband processing.
S103：According to the reference voltage obtained, the coupled signal after progress automatic growth control is converted into square-wave signal；
In this step, suitable reference voltage is selected, the coupled signal after progress automatic gain amplification is converted into square wave
Signal, for example, the coupled signal after carrying out automatic growth control is converted into square-wave signal using comparator.
In this step, as an alternative embodiment, reference voltage range is arranged on the coupling after carrying out automatic growth control
Crest voltage in a cycle of signal and between the crest voltage of second period.In order to further improve adaptability and
Stability, it is preferred that reference voltage is arranged for the peak value in a cycle of the coupled signal after automatic growth control
Crest voltage and value the average value of voltage and second period.I.e. reference voltage can be chosen for peak point (default peak-peak
Value) and peak point before a cycle (expire width before, first crest in Fig. 6) ceiling voltage between value, for example,
Choose the average value of the ceiling voltage sum of a cycle before peak point voltage and peak point, or the voltage near average value
Value is as the reference voltage.
In the present embodiment, the coupled signal after progress automatic growth control is inputted to comparator, passes through the ratio of comparator
Compared with conversion, the square-wave signal output for having pulsewidth more stable is obtained.
In the present embodiment, as shown in fig. 6, the signal output waveform after being amplified using AGC,
So that the reference voltage selection of comparator has preferable stability.
S104：The upper fall time of square-wave signal is obtained, the average of the upper fall time of square-wave signal is asked for, obtains positive and negative
To the sampling period time to peak of coupled signal, the same sampling period time to peak based on following current, the coupled signal of adverse current with
And the parameter such as pipe diameter pre-set carries out flow detection.
In this step, on the basis of obtained square-wave signal, fall time in detection, and average is asked for be coupled
The peak time (the cycle peak time of coupled signal) of signal, in the present embodiment, due to detection be square-wave signal up and down
Along the time, the upper fall time of square-wave signal has very high stability so that testing result (flow detection) have compared with
High adaptability and stability.
In this step, upper lower edge be worth to be peak value in the sampling period time proximity point, with this time point
As the forward and reverse flight time, the discrete noise for being so advantageous to equalize unilateral edge reduces.
In this step, as an alternative embodiment, can be measured with passage time chip detection pulse square wave rising edge and
At trailing edge time point (upper fall time), obtain the crossing time of point of fixed potential within the half period of the coupled signal of echo
Point, then being averaged by rising edge and trailing edge time point, obtain time to peak point (coupling letter of the coupled signal in the sampling period
Number the cycle peak time), so as to based on following current, the coupled signal of adverse current cycle peak time and pre-set
The parameters such as pipe diameter carry out flow detection.
In the present embodiment, the upper lower average along time point of square-wave signal is closer to coupled signal in the crest in the cycle
Between, so as to using relatively stable up/down along time point come the peak time point in approximate current detection cycle.
In the present embodiment, after ultrasonic coupling signal entered band logical enhanced processing, output signal is carried out by AGC chips automatic
Gain is enlarged into peak-to-peak value 2V signal, by the comparator with stable reference level, converts the signal into square wave letter
Number, then passage time measurement chip, the up/down of square-wave signal is detected along time point, obtaining up/down along after the time, calculating
The average time at two time points obtains the peak point time of coupled signal.The positive/negative survey to the time is completed by this method
Amount, then calculates forward and reverse time difference, and the time difference is exactly that the original time of time difference ultrasonic amount detection is poor.
In the embodiment of the present invention, the mode of multiplication factor is adjusted with respect to software processing, the embodiment of the present invention
Method does not have to the size for considering echo-signal, using the automatic gain enlarging function of AGC chips, as long as in AGC (automatic gain controls
Device processed) in chip amplification range, the output signal for the peak-to-peak value (for example, 2V) that can be fixed, after ensureing after school
The output square wave of continuous comparator is stable, and the square-wave signal being converted into can preferably ensure the stabilization of upper lower edge, then pass through the side of taking
The upper fall time of ripple signal, the mode of time to peak point is then asked for, can preferably ensure the echo-peak of coupled signal
The stability of point so that it has well adapting to property in liquid, detection of gas flow rate.
Below in conjunction with the accompanying drawings and specific embodiment the invention will be further described.
In ultrasonic flow rate detection signal processing method provided in an embodiment of the present invention, including：(1) ultrasonic coupling signal is through band
Logical amplification；(2) using AGC fixed amplitude output enlarging function, the output amplitude of signal is made to be stabilized to fixed peak-to-peak value；
(3) square-wave signal is obtained by voltage comparator；(4) up/down of square-wave signal is detected along time point；(5) calculate up/down along when
Between the time to peak of the average put as coupled signal；(6) using the above method obtain it is positive/negative to time to peak and make the difference, obtain
To propagation time difference；(7) parameter such as flow information passage time difference and caliber is calculated.Wherein
Ultrasonic coupling signal：Because circuit and ultrasonic coupling chip have certain noise, ultrasonic coupling chip passes through coupling
Certain noise be present and (made an uproar outside including industrial frequency noise present in white noise, circuit and other bands in obtained ultrasonic signal
Sound), if the signal is directly used in comparator and carries out time difference detection, easily cause testing result unstable, so as to influence flow
Testing result；On the other hand, when being propagated due to ultrasound in gas and liquid, signal amplitude can be in bubble, fine particle, pressure
Changed under the conditions of power, temperature etc., so that certain change be present in amplitude in the coupled signal directly obtained, its signal
As shown in Figure 4.
On the basis of above-mentioned signal, in order to effectively eliminate various noises (outside such as white noise, industrial frequency noise and other bands
Noise), it is to improve ultrasonic flow rate to examine to design and effectively to eliminate influence of the signal noise to testing result using bandpass amplifier
The committed step surveyed.In the processing of the algorithm, coupled signal is entered using the bandpass amplifier of same tranmitting frequency always
The band logical enhanced processing of the fixed multiplication factor of row and frequency, so as to eliminate influence of the various noises to detection stability, it amplifies
Output signal is as shown in Figure 5.
The main purpose of AGC (automatic growth control) amplifying circuit is the adaptive processes to coupled signal changes in amplitude,
Because coupled signal is after the amplifier processing of fixed multiplication factor and passband, the changes in amplitude of signal is not in this process
In be effectively addressed, bandpass amplifier output signal in amplitude there is also certain situation of change, particularly in pipeline
In bubble, fine particle be present when.Using AGC chips adjust automatically multiplication factor and make signal output amplitude stabilization
In the function of fixed peak-to-peak value, input signal can be made in the case of changes in amplitude, keep stable voltage output.Band logical is put
Greatly combine the processing mode output signal, have signal amplitude stably, out-of-band noise it is small, to coupled signal with larger adaptation
The advantages that property, its input signal is as shown in Figure 6.
The main purpose of time difference ultrasonic amount detection is to obtain stabilization, high-precision forward and reverse time difference, by upper
The signal of band logical and AGC the amplification output in face has well adapting to property and steady to signal noise, amplitude etc. to a certain extent
It is qualitative, the problems such as regular hour delay, shake be present yet with circuit, in order to obtain the time difference value of degree of precision, echo
The peak value of signal is the time difference test point of most stability, and in comparison circuit design, the processing method selects the ginseng of comparator
Between the crest voltage for examining crest voltage and second period of the voltage range in a cycle, had by comparing
The more stable square wave output of pulsewidth, as shown in Figure 7.
The rising of passage time measurement chip detection pulse square wave and fall time point (as shown in Figure 8), can be returned
The crossing time in half period content point of fixed potential of ripple signal, by being averaged for the two time points, it can be coupled
Time to peak point of the signal in the cycle.Forward and reverse ultrasonic flight time and the time difference of calculating are obtained by this method, can be obtained
To the ultrasonic flow rate detection signal with higher temperature and with preferable adaptability.
The present invention is made into one with reference to transit time ultrasonic flow meters measuring principle and the principal element for influenceing measurement
Step description.
First, the measuring principle of transit time ultrasonic flow meters
The general principle of ultrasonic flowmeter is:Deposited when using ultrasonic wave, following current, adverse current propagate same distance in a fluid
In the time difference, and the flow velocity of the difference in propagation time and detected fluid has relation, therefore the difference can for measuring the time is drawn
The flow velocity of fluid, also can calculate the flow of fluid.The research object of this problem is transit time ultrasonic flow meters, below
Its measuring principle will specifically be introduced.
From the measuring principle it can be seen from the figure that of the time difference method ultrasonoscope shown in Fig. 2, two ultrasonic transducer difference
Installed in the both sides of detected fluid caliber, the direction of propagation of ultrasonic wave in a fluid can be changed by certain mode, passed through
The following current in a fluid of measurement ultrasonic wave and adverse current propagation time difference can measure the flow velocity of fluid indirectly, and then calculate stream
Value.
Transit time ultrasonic flow meters measurement is the propagation time of ultrasonic wave in a fluid, by measuring ultrasonic wave suitable
Stream and propagation time difference △ t during adverse current obtain the flow of fluid, and concrete principle is as follows:
If ultrasonic wave downstream propagation times t1For:
Ultrasonic wave adverse current propagation time t2For：
Wherein D is pipe diameter, and v is the flow velocity of detected fluid, and c is spread speed of the ultrasonic wave in stationary fluid, and θ is
Ultrasonic wave launch angle.
Formula (2.1) is subtracted each other with formula (2.2)：The propagation time difference △ t of ultrasonic wave concurrent-countercurrent are:
Because the speed c that ultrasonic wave is propagated in stationary fluid is far longer than the actual flow velocity v of detected fluid, i.e. c>>v.
Therefore can obtain:
c2-v2cos2θ≈c2 (2.4)
Then (2.4) formula can be reduced to:
V in (2.6) is moved on to the left side of equation can obtain its calculation formula:
In formula (2.7), speed c of the ultrasonic wave in stationary fluid is usually taken to be constant, typically about 1500m/s, because
This, the flow velocity v of detected fluid is only relevant with parameter D, ultrasonic wave launch angle θ, time difference △ t, and D and θ is considered as systematic parameter,
Therefore as long as flow velocity v can be tried to achieve by measuring time difference △ t, and then try to achieve flow Q.For circular pipe, flow rate calculation is public
Formula is:
Wherein, K is rate of flow of fluid correction factor.
As long as the propagation time difference △ t can meters for measuring ultrasonic wave concurrent-countercurrent are can be seen that from measuring principle above
Calculation obtains flow value, and therefore, high-precision flow measured value can just be obtained by obtaining the higher △ t values of precision.
2nd, the factor of transit time ultrasonic flow meters measurement accuracy is influenceed：
Under non-ideal conditions, the factor such as tube wall propagation time, Flow Field Distribution will influence measurement result, directly contribute by
The result that according to reason opinion is calculated is inaccurate.The factor of influence transit time ultrasonic flow meters measurement accuracy may be summarized to be following
Some:
(1) influence of the law of refraction.Sound wave can reflect when different dielectric surfaces occurs incident, herein, sound
Fluid media (medium) difference inside wedge, tube wall and pipeline can reflect, and it is poor thus to produce the regular hour.
(2) temporal difference caused by transmitting driving.When the pulse signal that single-chip microcomputer transmits is delivered to transducer A respectively
During with B, because A and B is two different transducers, even if model is identical, it is also not possible to accomplish two transducers in performance
Definitely consistent, this has resulted in the time difference caused by signal transmitting.
(3) time difference caused by signal receive process.Two transducers have two receiving channels, and two receiving channels differ
Fixed full symmetric, this, which will result in, has the extra time difference to be mixed into reception signal.
Except more than some, it is also possible to the factor for influenceing transit time ultrasonic flow meters measurement accuracy is additionally included in reality
In, the mobility status of fluid is sufficiently complex in industrial pipeline, and the temperature inside and outside pipeline may also have larger difference, influences
The factor of transit time ultrasonic flow meters measurement accuracy may be summarized to be uneven temperature change, velocity flow profile, pipe thickness, sound
The factors such as road delay.Popped one's head in because present most ultrasonic flowmeter is more in actual applications using external clamping, institute
It can not considered with change this factor for popping one's head in recess flow velocity for it.If circuit, sound travel are using near symmetrical
If design, it can also not considered for electricity, the propagation delay of sound travel this influence factor.
The error of flowmeter can be finally concentrated in the influence of temperature change, therefore should focus on to consider this respect in designing
Factor, take corresponding measure to avoid influenceing.Influence for temperature convection speed, can be seen that wherein from the formula derived
Comprising velocity of sound c to be acted upon by temperature changes be bigger, fluid temperature (F.T.) inside and outside pipeline and environment temperature difference are smaller
When this influence can be ignored, but when the difference of this temperature is larger, this parameter will greatly influence the survey of flow velocity
Measure result.Influence problem of the temperature factor to be solved to flow velocity c, the present invention use modified time difference method.
3rd, modified transit time ultrasonic flow meters principle
The ultrasonic transducer mounting means that the present invention uses is installed for V-type, is improved type so that V-type is installed as an example below
The principles and methods of time difference method.
Under conditions of forward and reverse time measurement, the party can be used detect air-liquid body flow by time difference method
Method come handle (under V-type installation, due to ultrasonic wave propagation path be same caliber with semipath install 2 times of Z-type), ultrasonic wave
2 times when following current, adverse current propagation time also install for Z-type, formula is as follows：
Wherein t1For following current when propagation time, t2For adverse current when propagation time
Two formulas are respectively deformed into following form：
The formula of the above two subtracts each other to obtain
The calculating formula now obtained theoretically eliminates C, and then avoids the survey of temperature convection rate of flow of fluid in theory
The influence of amount, that is, avoid the influence to flow measurement.
Scheme determines：
Based on above theory analysis, the ultrasonic flowmeter that the present invention designs uses time difference method principle, and V-type is installed, according to
Modified computational methods carry out data processing, avoid the influence of this key influence factor of temperature, improve the design's as far as possible
Measurement accuracy.The v derived by improved algorithm calculating formula can see, after pipeline and ultrasonic probe install, D
Just determined with two parameters of θ, influence v only ultrasonic wave time and tide propagation time t1And t2If the two time resolutions
The precision of high then final flow rate measurement is also high, therefore Given this factor selects TDC-GP22 when selecting the Primary Component of the design
High precision time measurement chip, overall precision is improved with this.
Realize and be further described with reference to ultrasonic flow rate detection signal processing method provided by the invention.
Fig. 3 is ultrasonic flow rate detection signal processing method implementation process figure provided in an embodiment of the present invention.Specifically include：
(1) time difference ultrasonic quantity measuring method, mainly flown by measuring forward and reverse of the ultrasonic wave in pipeline
The row time, the flow velocity of gas liquid and unit interval in pipeline then is calculated to time difference and pipe diameter by positive/negative
Flow；(2) ultrasonic transducer is during the forward and reverse flight time is detected, due to the pressure of gas liquid, temperature in pipeline
The change of degree, bubble, particle etc., original coupled signal can have amplitude difference, while also deposit also to exist and made an uproar outside certain band
Sound；(3) main purpose of band logical amplifying circuit is to eliminate the noise in coupled signal, and it is a certain degree of to obtain coupled signal
Amplification, while the impedance operator of coupled signal is improved, it is easy to follow-up signal processing and impedance matching；(4) because band logical amplifies electricity
Road is set according to the supersonic frequency of different transmission signals, and its multiplication factor and output signal can be according to coupled signals
Amplitude size and certain difference be present.Due to the automatic gain enlarging function of AGC chips, in the feelings of amplitude output signal change
Under condition, output can be made to stablize in fixed output amplitude by adjust automatically multiplication factor (1-100 times), the characteristic is in chip
In the range of multiplication factor, there is well adapting to property to the input signal of different amplitudes, so that the output by AGC amplifications is believed
With stable output number in coupled signal changes in amplitude.(5) amplify with most of direct-coupling signals and pass through comparator
The mode for being converted to square wave is compared, and the signal of AGC outputs adapts to the coupled signal of different amplitudes due to amplitude stabilization,
Under the conditions of this, the datum of comparator input terminal is more more stable than the method for directly amplifying and being compared, and datum
Selection has preferable stability, while the output square wave of the program has in width and on the time stronger stability；(6) when
Between measurement chip be mainly used in measurement from transmitting pulse to termination power processing after comparator output pulse total flight time, by
In the change of circuit noise and coupled signal amplitude, under conditions of AGC enhanced processings are not carried out to signal, detect what is obtained
Larger saltus step be present (particularly under conditions of accuracy of detection requires higher, as time difference precision reaches a 50ps left sides in the flight time
It is right) so that whole system can not meet testing requirements.Because the peak point of coupled signal is the relatively stable time
Point, preamble signal is handled and and on the basis of comparing output, (such as GP22 is counted at a high speed sampling time measurement chip
Number devices etc.) at the same detection comparator output square-wave signal rising and trailing edge time, and ask for the average at two time points, profit
When the approximation by the use of this average as coupled signal peak point, forward and reverse flight time is obtained using this method, and calculating current
Between difference and instantaneous delivery.The time difference ultrasonic amount signal processing method changes from signal amplitude and the stability of time difference detection
Etc. improve the unidirectional flight time and the two-way time difference accuracy of detection and stability.
Embodiments of the invention also provide a kind of ultrasonic flow rate detection signal processing unit, the ultrasonic flow rate detection signal
Processing unit includes：Bandpass amplifier, automatic gain controller, voltage comparator, high precision time measurement chip and flowmeter
Device is calculated, wherein,
Bandpass amplifier, it is consistent with tranmitting frequency, for coupled signal being fixed multiplication factor and baseband processing；
Automatic gain controller, for carrying out automatic growth control to the coupled signal after baseband processing, so as to carry out certainly
The signal output amplitude stabilization of coupled signal after dynamic gain control is in the peak-to-peak value pre-set；
Voltage comparator, for according to the reference voltage obtained, the coupled signal after progress automatic growth control to be changed
For square-wave signal；
High precision time measurement chip, the up/down for detection comparator output square-wave signal are follow-up along time point
It is positive/negative to provide high-precision time basis to time to peak；
Airflow calculator, the positive/negative sampling period peak value to propagation of coupled signal is calculated along time point by up/down
Time, and carried out according to parameters such as following current, the cycle peak time of the coupled signal of adverse current and the pipe diameters that pre-sets
Flow detection.
In the present embodiment, the signal amplitude of the coupled signal after the baseband processing is in the progress automatic gain amplification pair
The signal amplitude input range for the automatic gain controller answered is interior and is amplified effective adjust automatically of multiple.
In the present embodiment, the reference voltage range is arranged on first of the coupled signal after carrying out automatic growth control
Between the crest voltage in cycle and the crest voltage of second period.
In the present embodiment, the reference voltage is the crest voltage of a cycle and the peak of the second period
The average value of threshold voltage sum.
The foregoing is merely illustrative of the preferred embodiments of the present invention, is not intended to limit the invention, all essences in the present invention
All any modification, equivalent and improvement made within refreshing and principle etc., should be included in the scope of the protection.
Claims (6)
- A kind of 1. ultrasonic flow rate detection signal processing method, it is characterised in that the ultrasonic flow rate detection signal processing method bag Include：Coupled signal is amplified using same tranmitting frequency consistent bandpass amplifier and eliminates most of out-of-band noise；Automatic gain amplification is carried out to the coupled signal of band logical output, makes the output of the coupled signal after carry out automatic gain amplification The peak-to-peak value that amplitude stabilization is set in chip；Suitable reference voltage is selected, the coupled signal after progress automatic gain amplification is converted into square-wave signal；The upper fall time of square-wave signal is obtained, the average of the upper fall time of square-wave signal is asked for, obtains taking for coupled signal The sample cycle peak time, based on following current, the same sampling period time to peak of the coupled signal of adverse current and the pipe that pre-sets Road diameter parameters carry out flow rate calculation.
- 2. ultrasonic flow rate detection signal processing method as claimed in claim 1, it is characterised in that the coupling after the baseband processing Close signal amplitude input range of the signal amplitude in automatic gain controller corresponding to the progress automatic gain amplification of signal Effective adjust automatically that is interior and being amplified multiple.
- 3. ultrasonic flow rate detection signal processing method as claimed in claim 1, it is characterised in that the reference voltage range is set Put the crest voltage of a cycle and the crest voltage of second period of the coupled signal after automatic gain amplification is carried out Between.
- 4. ultrasonic flow rate detection signal processing method as claimed in claim 3, it is characterised in that the reference voltage is described The crest voltage of a cycle and the average value of the crest voltage sum of the second period.
- A kind of 5. ultrasonic flow rate detection signal processing dress of ultrasonic flow rate detection signal processing method as claimed in claim 1 Put, it is characterised in that the ultrasonic flow rate detection signal processing unit includes：Bandpass amplifier, automatic gain controller, voltage Comparator, high precision time measurement chip and airflow calculator, wherein:Bandpass amplifier, it is consistent with tranmitting frequency, for coupled signal being fixed multiplication factor and baseband processing；Automatic gain controller, for carrying out automatic growth control to the coupled signal after baseband processing, so as to be increased automatically The signal output amplitude stabilization of coupled signal after benefit control is in the peak-to-peak value pre-set；Voltage comparator, for the reference voltage according to acquisition, by the coupled signal side of being converted to after progress automatic growth control Ripple signal；High precision time measurement chip, the up/down for detection comparator output square-wave signal are follow-up positive/negative along time point High-precision time basis is provided to time to peak；Airflow calculator, by up/down along time point coupled signal positive/negative sampling period peak value to propagation is calculated when Between, and flowed according to parameters such as following current, the cycle peak time of the coupled signal of adverse current and the pipe diameters that pre-sets Amount detection.
- A kind of 6. time difference method ultrasound inspection using ultrasonic flow rate detection signal processing method described in any one of Claims 1 to 44 Examining system.
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