CN104374447B - Guided wave formula radar levelmeter echo signal processing method based on first derivative and combination reference curve - Google Patents
Guided wave formula radar levelmeter echo signal processing method based on first derivative and combination reference curve Download PDFInfo
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Abstract
The present invention relates to a kind of guided wave formula radar levelmeter echo signal processing method based on first derivative and combination reference curve.This method includes：1. constructing reference curve, 2. signal preprocessings, 3. thing position echoes judge that 4. propagation times calculated, and 5. calculate thing place value；The signal for including " step " part not being superimposed with thing position echo need to be stored in advance as reference curve, judged for follow-up thing position echo；9 moving average filtering pretreatments are carried out to echo-signal；First derivative is carried out to filtered signal and calculates detection echo, multi-parameter combination reference curve judges thing position echo, determines thing position echo-bearing point and calculates the propagation time with reference to starting point；Any 3 points of selection is entered rower and determined in restriction section, determines thing position propagation time model；Finally, the propagation time is substituted into thing position and the functional relation between the propagation time, obtains thing place value.
Description
Technical field
The invention belongs to Level measurement technical field, and in particular to it is a kind of using single-chip microcomputer as core based on first derivative simultaneously
With reference to the method for the processing guided wave formula radar levelmeter echo-signal of reference curve.
Background technology
Guided wave formula radar levelmeter carries out level gauging using the echo ranging principle in Radar Technology, is widely used in work
Industry field.The difficult point of guided wave formula radar levelmeter echo signal processing is judgement and the echo-bearing point of true thing position echo
It is determined that.Wherein, thing position echo determines whether measurement is accurate, and echo-bearing point influences accuracy of measurement.
For the key issue of guided wave formula radar levelmeter signal transacting, external a few famous producers of family, for example, E+H companies,
Emerson Rosemount companies and Siemens-Milltronics companies decile do not propose different echo signal processings
Method.Rosemount INC. (US) 12001 West 78th Street Prairie, Minnesota 55344 U.S.A.（“Method of determining a disturbance echo profile for a
radar level gauge system”, U.S Patent: No.7924216 B2, Apr.12,2011）Describe one kind
Method based on reflector, according to the reflector waveform construction reference curve under the conditions of slack tank, by comparing actual range and electricity
Gas distance determines reflector nearest on liquid level, obtains reference curve application, can be eliminated after subtracting each other dry on liquid level
Echo is disturbed, thing position echo is then determined according to maximum.Rosemount INC. (US) 12001 West 78th Street Prairie, Minnesota 55344 U.S.A.（“System and method for filling
level determination”, U.S Patent: No.7525476 B1, Apr.28, 2009.）Describe in guided wave bar
Known position installs reflector, and spread speed is compensated by the known distance of a pair of known reflectors and the difference of measurement distance
Along the change of guided wave bar, to improve accuracy of measurement.Rosemount INC. (US) 12001 West 78th Street Prairie, Minnesota 55344 U.S.A.（" by multi-mode propagation there is dielectric constant to mend
The guided wave formula radar level gauge system repaid ", China, CN201120366374.7,2012-6-6.）Describe a kind of special lead
Ripple bar, referred to as incomplete outer dielectric transmit detector, can support the communication mode of two kinds or more friction speeds, Ran Hougen
Dielectric constant and spread speed are determined according to formula.
Chinese invention patent（" a kind of system and method for handling guided wave formula radar levelmeter echo-signal ", the patent No.:
ZL 201210150945.2, the applying date：2012-9-12, grant date：2013-9-11）Describe for differing dielectric constant
Not jljl position echo determination methods.The patent is with above-mentioned patent identical place：Reference curve is constructed according to slack tank signal；It is right
Echo-signal section has carried out the pretreatment of Butterworth low pass ripple；The judgement of thing position echo can regard two steps as, first according to derivative
Echo is detected, and sets width range to exclude part interference, then looks for the maximum for being higher by reference curve true remaining echo
Earnest position echo；Echo-bearing point is determined by 2 rank Lagrange interpolation points of peak point and adjacent 2 points；Nominal data is 4 ~ 10
The linear interpolation of point or 3 fittings.Difference with above-mentioned patent is, for small dielectric constant dielectric, reference curve needs to make
Fill and lead up the amendment of coda wave；Echo-signal section has carried out slope amplification to highlight variation tendency；Echo-signal section subtracts reference curve
Net echo-signal section is obtained, and processing afterwards is all directed to the signal.
The problem of patent is present be：Butterworth low pass ripple is a kind of frequency domain filtering method, applied to frequency domain character
Unconspicuous guided wave formula radar levelmeter echo signal processing, it is ineffective；Construction reference curve needs first to construct slack tank condition,
, it is necessary to be vented material during applied to actual production, and need to update, otherwise can not exclude new caused interference echo；Echo is believed
Number subtract each other the nonlinear moving that may result in echo-bearing point with reference curve, influence measurement accuracy.
Therefore, application Chinese invention patent (the guided wave formula radar levelmeter echo signal processing system based on first derivative
And method, application number：201310534738.1 the applying date：On November 1st, 2013) provide a kind of processing and touched without lock-out pulse
The system and method for the guided wave formula radar levelmeter echo-signal of hair.Employ the detection of the method based on first derivative echo, deposit
Echo multiple parameters, such as end points, peak point, width, slope amplitude have been stored up, and based on the organic assembling determination to these parameters
Thing position echo；Propose the method for sampling for the guided wave formula radar levelmeter without triggering sampling and the determination side with reference to starting point
Method；Using 3 points, minute two sections of linear calibrations.This application patent of invention does not need slack tank condition, and practical operation is simple.
The problem of this application patent of invention is present be：The limitation of echo parameter suppression ratio may cause to exclude true echo or
Can not exclusive PCR echo cause to sentence mistake；Peak-peak point is obtained as characteristic point using row interpolation is entered to true echo, is carried out
Demarcation and measurement, its linearity is not best, i.e., accuracy of measurement is not best；60 medians are carried out to measurement result
Average filter, response speed are slower.
The content of the invention
In view of the above problems, the present invention provides a kind of guided wave formula radar thing position based on first derivative and combination reference curve
Echo signal processing method is counted, so as to reach relatively reliable to the accurate judgement of thing position echo, reaches and reduces blind area, improves measurement
Precision, response speed require faster, and to hardware requirement it is not high, slack tank condition need not be constructed.
A kind of guided wave formula radar levelmeter echo signal processing method based on first derivative and combination reference curve includes
(1) reference curve, (2) signal preprocessing are constructed, (3) thing position echo judges that (4) propagation time calculates, and (5) calculate thing position
Value；Concrete operations are：Storage in advance includes the signal of " step " part not being superimposed with thing position echo as reference curve, uses
Judge in follow-up thing position echo；9 moving average filtering pretreatments are carried out to echo-signal；Single order is carried out to filtered signal
Derivative calculations detect echo, and multi-parameter combination reference curve judges thing position echo, determine thing position echo-bearing point and with reference to starting
Point calculates the propagation time；Any 3 points of selection is entered rower and determined in restriction section, determines thing position-propagation time model；Finally, will
Propagation time substitutes into thing position and the functional relation between the propagation time, and thing place value is calculated.
Specific technical solution is as follows：
For the guided wave formula radar levelmeter without synchronous trigger pulse, sampled because no synchronizing signal triggers ADC,
Therefore it needs to be determined that first sampling point, guarantee collect correct signal segment.One complete echo-signal includes a side
Wave impulse and positioned at some reflection echos thereafter.Have before this echo-signal with next square-wave pulse longer steady
Section, without obvious echo, and square-wave pulse has precipitous rising edge and trailing edge.According to this feature of signal, ADC's
Sampled point is judged in interrupt service subroutine, when it is determined that having collected the trailing edge of square-wave pulse, 1000 points after preservation
The data of length, the echo-signal section as subsequent treatment.The surface of material, " platform of sensor itself are included in echo-signal section
The reflection echo, referred to as echo caused by factor such as rank " interference, noise.The specific processing step of echo-signal is as follows：
(1) reference curve is constructed
The 2 points of interference formed for " step " intrinsic in level meter signal：1）When thing position is less than 25cm, thing position echo
Amplitude is less than noise level thereafter；2）" step " feature itself is approximate with thing position echo.Therefore, it need in advance store and include not
The signal of " step " part being superimposed with thing position echo judges as reference curve for follow-up thing position echo；Tank is highly fixed
Value, when guided wave formula radar levelmeter is arranged on tank deck, guided wave bar vertically downward, define guided wave formula radar levelmeter flange following table
Face to the distance of surface of material be thing position.Make thing position by increasing or decreasing material for the arbitrary value more than 70cm, then at random
One group of echo-signal is gathered, is intercepted from starting point to having comprising " step " part not being superimposed with other echoes intrinsic in signal
Imitate the signal segment of reflection echo signal；For example, when Sampling starting point is square-wave pulse trailing edge, the part is starting point to sampled point
For a bit in 255~305 points.When Sampling starting point is that square-wave pulse rising edge originates, the part may be extended to from
It is a bit in 450~500 points to put to sampled point.
(2) 9 moving average filterings are carried out to echo-signal section, reduces noise, smooth shake.
(3) it is comprising effective reflection echo part, for example, being for 1m stocks, Sampling starting point to set echo seeking scope
During square-wave pulse trailing edge, sampled point 230 ~ 500 point are may be configured as, eliminate the guided wave bar connection point reflection of section start fixation
The influence of echo, and reduce the length of unnecessary signal transacting.Calculate 1 order derivative signal of echo-signal section in the range of this, the calculation formula after simplification is
In formula,For echo-signal section,For the point on signal.
(4) to 1 order derivative signalJudged from the off.If、Contrary sign, andMore than 0,
Then determine the starting point start [i+1] that n is terminal end [i] and next echo；If、Contrary sign, andLess than 0,
And starting point determines mark set, it is determined that n is peak point peak [i]；I represents echo sequence number.
(5) characteristic point of echo has been recorded, i.e., after the starting point of echo, peak point, terminal, has calculated the width w of the echo
[i], first derivative maxima and minima difference, referred to as rate of change amp [i], and compared with preset value, less than default
The echo of value excludes, the echo of reservation alternately echo, can be with exclusive PCR echo, and the interference echo is random narrow spike
Pulse, small size noise echo.The calculation formula of above-mentioned each characteristic parameter is：
In formula,dataFor echo-signal section,d_max、d_Min represents first derivative maxima and minima respectively,iTo return
Wave train number.
(6) to 1 order derivative signalIn the range of all points judged according to step (4)~(5), it is alternative to obtain several
Echo.
(7) alternative echo is judged, the echo at " step " scope is made comparisons with reference curve, if discontented
Foot is more than 100~110 numerical value, then excludes the echo；Otherwise, retain.
(8) confidence level is carried out to each alternative echoconfidenceCalculate, formula is as follows：
In formula,iFor alternative echo sequence number,dataFor echo-signal section,peakFor alternative echo-peak point.
(9) it is thing position echo to determine alternative echo corresponding to maximum confidence.
(10) minimum slope point is asked for thing position echo, and 2 rank Lagrange interpolation is carried out on first derivative curve, really
Earnest position echo-bearing point；It is more selected around at fixation reflex echo guided wave bar tie point reflection echo trailing edge midpoint, with
Straight line where the point intersects with the echo trailing edge, and linear interpolation obtains referring to starting point；Then propagation time, the biography are calculated
=thing position echo-bearing point-refers to starting point between sowing time.
(11) limit filtration is carried out to the propagation time, excludes erroneous calculations result caused by random disturbances reason, and preserve.
(12) to same thing position, the propagation time of more than 40 times for calculating preservation carries out median average filter, finally tied
Fruit is as the propagation time corresponding to the thing position.
The propagation time is substituted into by demarcating in the thing position of determination and the functional relation between the propagation time, calculated
Obtain thing place value.
In formula,LFor thing position,tFor the propagation time,k,bTo demarcate relational expression coefficient,t 1 For time point of demarcating.
The advantageous effects of the present invention embody in the following areas：
1. with HeFei University of Technology's patent（" a kind of system and method for handling guided wave formula radar levelmeter echo-signal ":
China, CN201210150945.2,2012-9-12.）Compare, the present invention is no to distinguish size dielectric constant, reference curve
Construction does not need slack tank condition, therefore easier；The method based on first derivative and combination reference curve is employed to detect back
Ripple, echo multiple parameters, such as end points, peak point, width are stored, and combined and formed based on the different modes to these parameters
Rule of judgment determines thing position echo, and the setting of reference curve can exclude sensor and inherently disturb, and the bar that multiple parameters are formed
Part is then applied to extra, random interference, avoids the more new demand to reference curve, and by blind area（Within 30cm）、
Water, oil under metal interference（Small dielectric constant）, long range measurements echoes checking, it was demonstrated that validity；Propose and be directed to nothing
Trigger the method for sampling of the guided wave formula radar levelmeter of sampling and the determination method with reference to starting point；Using 3 points, minutes two sections it is linear
Demarcation, therefore practical operation is simpler, and maximum error of measuring is within ± 1cm；
2. apply for a patent (the guided wave formula radar levelmeter echo signal processing system based on first derivative with HeFei University of Technology
System and method, application number：201310534738.1 the applying date：On November 1st, 2013) compare, the present invention eliminates " suppression ratio "
Condition limitation, add the contrast with reference curve, improve the reliability that thing position echo judges, occur sentencing mistake in former patent
In the case of, this patent can be with accurate judgement；Starting sample point is set to the trailing edge of transmitting square-wave pulse, reduces at 200 points
Unnecessary collection；By the use of the interpolation point of minimum slope point as thing position echo-bearing point, thing position-propagation time model is improved
The linearity；60 groups of median average filters are reduced to 40 groups of median average filters, improve response speed；Using 3 points minutes
Two sections of linear calibrations, specify that 3 points of interval and the value of waypoint.
Brief description of the drawings
Fig. 1 is guided wave formula radar level gauge system theory diagram.
Fig. 2 is signal conditioning circuit figure.
Fig. 3 is the SCM system hardware circuit diagram based on MSP430F541A.
Fig. 4 is the SCM system software the general frame based on MSP430F5418A.
Fig. 5 is the SCM system master monitor flow chart based on MSP430F5418A.
Fig. 6 is slack tank, 66cm, 99cm echo-signal.
Fig. 7 is 9 moving average filtering design sketch.
Fig. 8 is coaxial 9 moving average filtering effects of echo-signal.
Fig. 9 is 15cm water levels and slack tank signal.
Figure 10 is 16cm and 100cm water level signals.
Figure 11 is thing position echo decision flow chart.
Figure 12 is 15cm water echo-signals.
Figure 13 is compared with the echo-signal under strong jamming.
Figure 14 is long range measurements echo-signal.
Figure 15 is propagation time sample sequence.
Figure 16 is propagation time sample probability density function.
Figure 17 is propagation time sample probability density function Gauss curve fitting.
Embodiment
Below in conjunction with the accompanying drawings, the present invention is further illustrated.
Referring to Fig. 1, guided wave formula radar level gauge system is by impulse sender, guided wave bar, equivalent time sampling circuit, signal
Modulate circuit, the SCM system based on MSP430F5418A and liquid crystal display composition.Wherein, equivalent time sampling circuit by
Pulse receiver, pulse daley sequence generator, frequency mixer composition.
Impulse waveform is produced by impulse sender, the signal is divided into two-way, amplifies shaping through preposition triggers circuit all the way, becomes
Into amplitude is larger, transmitting clock is delivered in forward position compared with the pulse signal trembled.Launch clock to send out along guided wave bar by transmitting antenna
Send periodic short pulse electromagnetic wave.Electromagnetic wave reflects to form a series of echo-signals on the interface of different medium, by
Reception antenna is sent to equivalent time sampling circuit after receiving.At the same time, time base circuit sends out another way pulse signal to mixing
In device, it is mixed with the echo impulse after tiny time postpones.Signal after equivalent time sampling becomes middle low frequency letter
Number, it is sent to single-chip microcomputer after conditioned circuit and is handled, result of calculation is by liquid crystal display.
Modulate circuit is as shown in Figure 2.Power circuit uses linear regulator chip TPS71530 U4 to be carried for signal condition system
For 3V supply voltage, the 3.3V voltages introduced by outside obtain stabilization, pure 3V voltages after power circuit, are system
Power supply；Bleeder circuit is made up of transport and placing device U1A, resistance R6 and R7；Resistance R6 and R7 ratio determine intrinsic standoff ratio, transport and placing device
U1A is adopted as series voltage negtive backword connection, has high input impedance and low output impedance；DC bias circuit is by transport and placing device
U2A, U2B and resistance R8, R9 and R11, R12 and electric capacity C8 compositions；Electric capacity C8 plays blocking, resistance R8 and R9, R11 with
R12 ratio determines multiplication factor, after two-stage direct current biasing, output voltage V0=Vref+Vin；Reference voltage produces electricity
It route transport and placing device U1B, resistance R14 and R15, electric capacity C10 compositions；Resistance R14 and R15 ratio determine the reference voltage of output
Value；Transport and placing device U1B follows and cushioning effect.Due to the amplitude of the echo-signal of equivalent time sampling circuit output be 0V extremely
4.7V, and MSP430F5418A single-chip microcomputers U3 only allows the electrode of input 0 to 3.3V, so, equivalent time is adopted
The echo-signal of sample circuit output is nursed one's health；The echo-signal of equivalent time sampling circuit output is connected to signal conditioning circuit
Middle resistance R6 left end；Echo-signal enters bleeder circuit, and by partial pressure, its amplitude is reduced to the 1/3 of open width value；Then, enter
Enter DC bias circuit, the DC component in signal is separated by electric capacity C8, and 1.25V is raised to by voltage offset electric circuit, and be
The half of ADC reference voltage in MSP430F5418A singlechip chips.
Echo-signal after conditioning is connected to the pin 7 of MSP430F5418A U3 single-chip microcomputers, and pin 7 is P7.6/A14, such as schemes
Shown in 3.The pin 7 of MSP430F5418A single-chip microcomputers is multiplexing pins, is configured as simulation input A14-ADC herein, will be returned
Ripple signal is delivered to ADC in MSP430F5418A single-chip microcomputers U3 piece and (indicated：ADC as described below is MSP430F5418A monolithics
ADC in the piece of machine).The output Vref of reference voltage generating circuit in Fig. 2 is connected to the Vref for DC voltage bias circuit, is
DC voltage bias circuit provides reference voltage.
SCM system hardware circuit based on MSP430F5418A as shown in figure 3, by MSP430F5418A single-chip microcomputers U3,
Liquid crystal display (LCD) interface P2 and emulator interface P3 are formed.TI companies MSP430F5418A single-chip microcomputers are selected as core
Processor, it is because it has the characteristics that super low-power consumption, powerful disposal ability, abundant peripheral module, is completely suitable for leading
The requirement of waves radar levelmeter signal transacting, and provide possibility for the two-wire system realization of guided wave formula radar levelmeter.
P2 is LCD interfaces in Fig. 3.The LCD is dot matrix, parallel interface.LCD data transfer pin 3 ~ 10 connects respectively
To MSP430F5418A single-chip microcomputers U3 I/O mouths 42 ~ 35,(chip selection signal),(reset),(register selects
Select),(write enable signal),(reading enable signal) is respectively connecting to MSP430F5418A single-chip microcomputers U3 pin
25-P2.0,26-P2.1,27-P2.2,28-P2.3,29-P2.4, completed by MSP430F5418A single-chip microcomputers U3 corresponding
Write operation, result is included on LCD.
P3 is artificial mouth in Fig. 3.Using personal computer and emulator, by this interface, complete to MSP430F5418A
Single-chip microcomputer U3 kernel operation, including program debugging and programming etc..
Fig. 4 is the SCM system software the general frame based on MSP430F5418A.System software uses modularized design
Method, by master monitor module, interruption processing module, initialization module, echo signal processing module, level meter calculate module and
LCD display module forms.
Master monitor module in Fig. 4 is the total activation program of the SCM system software based on MSP430F5418A,
By calling each program module, the function required by the system is realized.
Fig. 5 is the SCM system master monitor flow chart based on MSP430F5418A.It is a cyclic program.System
On system after electricity, master monitor automatic running, whole program carries out corresponding position by the way of setting to each subprogram
Reason.Its basic process is：System electrification, to each functional modules of MSP430F5418A single-chip microcomputers U3 and LCD display module variable
Initialized；Open system interruption, ADC successively, subsequently into low-power consumption mode；In the adc to sampling in disconnected service routine
Data are judged.If collecting the transmitting square-wave pulse trailing edge of signal, start to preserve sampled data, and record
Sampling number；When gathering at 1000, low-power consumption mode is exited, and close ADC；Echo signal processing is carried out to sampled signal,
Including：9 moving average filterings are carried out to echo-signal, the echo judgement of thing position is carried out to filtered signal, determines that echo is determined
Site and with reference to starting point to calculate the propagation time, processing be filtered to calculated value；Then, it will substitute into the propagation time and pass through mark
Surely the thing position determined and the functional relation between the propagation time calculate thing position；Then, as a result come out by liquid crystal display.
Lower mask body introduces echo signal processing, and it is most of to be divided into 5.
(1) reference curve is constructed
The 2 points of interference formed for " step " intrinsic in level meter signal：1）When thing position is less than 25cm, thing position echo
Amplitude is less than noise level thereafter；2）" step " feature itself is approximate with thing position echo.Therefore, it need in advance store and include not
The signal of " step " part being superimposed with thing position echo judges as reference curve for follow-up thing position echo.As shown in Figure 6
Slack tank signal, 66cm, 99cm signal contrast, their " step " partially overlap, it is seen then that adjustable material thing position, are allowed to be located at
Any one place after 70cm.At this moment echo-signal is gathered, intercepts and is stored from starting point to the point of sampled point 255 part, as reference
Signal.This has effect same with storage slack tank signal, still, avoids construction slack tank condition.Comparatively, so do more
It is convenient and practical.In the judgement of follow-up thing position echo, by being compared with reference curve, the interference of " step " can be excluded.
(2) signal preprocessing
Using 9 moving average filterings.The echo-signal of guided wave formula radar levelmeter is typical time-domain signal, in frequency domain
Do not show the characteristics of obvious.Burr, smooth shake can be eliminated by moving average filtering.Meanwhile this filtering mode
Signal amplitude can be caused to reduce, echo rate of change diminishes, it is therefore desirable to the points of reasonable selection moving average filtering.Pass through ratio
Compared with selecting 9 moving average filterings, formula is：
(1)
In formula,yFor filtered signal,nFor the point on signal,NCounted for signal.
9 moving average filterings substantially reduce signal jitter it can be seen from Fig. 7 and Fig. 8, and for coaxial in Fig. 8
Easily occur causing full width due to overflow when pipe measures thing position, the crest of echo-signal is scabbled, and echo-bearing point is not
Situation about easily determining, after 9 moving average filterings, a sharp crest of comparison can be obtained, is easy to subsequently calculate.Cause
This, pretreatment 9 moving average filterings of selection.
Table 1 compared for primitive curve, Butterworth filtering, 5 rolling averages, 9 rolling averages, 21 rolling averages
Filter effect.13 groups of echo-signals of random acquisition under same thing position are handled, calculate propagation respectively using same procedure
Time, sample variance and the difference of max min finally are calculated to this 13 group propagation time（It is designated as amplitude）, observed not with this
With pretreatment mode to signal stabilization degree, the improvement of repeatability.
The sample variance and amplitude minimum of 9 moving average filterings are can be seen that by the data of table 1, hence it is evident that less than original
Signal, improvement result are obvious.
(3) thing position echo judges
According to the characteristics of guided wave formula radar levelmeter signal：1) it is nonperiodic signal, does not have obvious characteristic in frequency domain, it is impossible to
Using frequency domain technique；2) signal does not have a master pattern, and interference echo is similar with thing position echo shape, it is impossible to by mutually putting into
Row detection.Therefore, its signal transacting is mainly carried out in time domain.
The difficult point of thing position echo identification includes：1) there are many fixed interference, including the reflection echo of guided wave bar tie point, position
In 230 points~255 points of sampled point（When Sampling starting point is square-wave pulse trailing edge）" step ", on Fig. 9 slack tank signals
Shown in arrow.The presence of " step " causes the thing position echo amplitude within 25cm or 30cm smaller, such as 15cm signals in Fig. 9；2)
Reflected according to scene, random narrow high impulse interference is there may be in actual signal, and amplitude is very big；3) interference caused by chaff interference etc.
Echo.Earliest using the method that maximum of points determines echo peak is looked for, therefore, there are 25cm or 30cm blind area, and easily sentence
Wrong situation, produce gross error.
Guided wave formula radar levelmeter echo signal processing system and method based on first derivative, (application number：
201310534738.1 the applying date：On November 1st, 2013）Propose a kind of thing position of the more characteristic parameters based on first derivative
Echo recognition methods, using the multiple parameters of echo, multiple Rule of judgment are bonded by different modes, enhance echo
The reliability of judgement.But be found through experiments that, when it is 0.5 to set suppression ratio, erroneous judgement occurs in some cases.It is former
Because being that in this case, the suppression ratio of thing position echo is again smaller than 0.5, as shown in Figure 10.Therefore, it is wrong in " roughing " stage
Misprint and remove.If suppression ratio is reduced, such as 0.2, because the two difference is little, at some thing positions, because the interference such as noise may
There is the situation that " step " can not be excluded, can still result in erroneous judgement.Therefore, improved on the basis of this method.
The judgement of thing position echo still using first a wide range of exclusion, the thinking that small range determines again, can regard two steps as：" roughing "
" selected ".Echo is detected when " roughing ", and preserves starting point, peak and end point.By setting the parameters such as Echo width
Exclusive PCR, it is determined that alternative echo.Peak point amplitude, width of alternative echo etc. are calculated when " selected " and weights sum as confidence
Degree, determines thing position echo.
Statistical analysis, including peak point amplitude, width are carried out to the echo character parameter of not jljl position in laboratory conditions
Degree, rate of change etc..Echo width and peak point amplitude reflect backward energy；Rate of change be on echo rising edge and trailing edge most
The difference of big slope and minimum slope, reflect echo change speed degree.From experimental data, thing position echo in most cases
With maximum amplitude, width is basicly stable, and still, echo superposition this case can cause width to become big；Rate of change is larger, still
Regular change is not presented with the time.Disturbance echo has different characteristics, it is difficult to determines that thing position is returned by single condition
Ripple.Therefore, being classified according to the characteristics of interference echo, form different condition and excluded.
" roughing " does not have for the Parameters variation section for excluding constant interval and thing position echo with one or more parameters
There are overlapping interference echo, including random narrow spike, the noise of width amplitude very little, by setting Echo width, change
The lower limit of rate is excluded.It is " selected " for excluding secondary or multiecho, echo caused by chaff interference and width is larger makes an uproar
Sound, because their Parameters variation section is overlapping with having for thing position echo, it is thus impossible to excluded by limiting scope, therefore
Using the method for the multiple calculation of characteristic parameters confidence levels of synthesis.
Disturbed for " step " intrinsic in level meter signal, if the interference echo is not excluded in " roughing " stage,
Higher value can be produced by then subsequently calculating confidence level, easily cause erroneous judgement.Therefore, before confidence level is calculated, " step " will be located at
Partial alternative echo and the reference curve stored in advance contrast, if being unsatisfactory for being more than reference curve certain limit, then it is assumed that should
Echo is itself " step ", is excluded.
To knowable to " roughing " afterwards the characteristic parameter statistical analysis of residual echo, width is smaller, peak point amplitude is bigger, change
The bigger echo of rate is bigger for the possibility of thing position echo.Therefore, the coefficient of width is negative when setting confidence calculations, represents wide
Degree is bigger, and the possibility of thing position echo is smaller.The difference that these three parameter number magnitudes of Main Basiss are set of weights, peak point width
It is worth for 103, rate of change 102Or 10, width 10.Rate of change, peak point amplitude, the width of confidence calculations are rule of thumb set
Weights, such as 0.6,0.1,0.3 are spent, the empirical equation for obtaining confidence calculations is：Confidence level=0.6 × rate of change+0.1 × peak
Value point amplitude -0.3 × width.
Signal processing flow figure is as shown in figure 11.
Comprise the following steps that：
(a) set echo seeking scope be comprising effective reflection echo part,
Tank is highly definite value, when guided wave formula radar levelmeter is arranged on tank deck, guided wave bar vertically downward, defines guided wave formula
Radar levelmeter flange undersurface to the distance of surface of material be thing position；Thing position is set to be more than 70cm by increasing or decreasing material
Arbitrary value, then one group of echo-signal of random acquisition, intercept and do not folded from starting point to comprising intrinsic in signal with other echoes
Effective reflection echo signal of " step " part added；
For example, be 1m for guided wave pole length, Sampling starting point is when being square-wave pulse trailing edge, may be configured as sampled point 230
, eliminate the influence of the guided wave bar tie point reflection echo of section start fixation at~500 points, and reduce unnecessary signal transacting
Length.Calculate 1 order derivative signal of echo-signal section in the range of this.Because the time interval of neighbouring sample point is fixed and very
It is short, replace first derivative to can reach the degree of accuracy with first-order difference, its calculation formula can be approximately：
(2)
Because consecutive points are at intervals of 1, formula (2) can be reduced to：
(3)
In formula,For echo-signal,For the point on signal；
(b) to first derivative signalJudged from the off, if、Contrary sign, andMore than 0,
Then determine the starting point start [i+1] that n is terminal end [i] and next echo；If、Contrary sign, andLess than 0,
And starting point determines mark set, it is determined that n is peak point peak [i]；I represents echo sequence number；
(c) characteristic point of echo has been recorded, i.e., after the starting point of echo, peak point, terminal, has calculated the width w of the echo
[i], first derivative maxima and minima difference, referred to as rate of change amp [i], and compared with preset value, less than default
The echo of value excludes, the echo of reservation alternately echo.Can be with exclusive PCR echo, the interference echo is random narrow spike
Pulse, small size noise echo etc..The calculation formula of above-mentioned each characteristic parameter is：
(4)
(5)
In formula,dataFor echo-signal section,d_max、d_Min represents first derivative maxima and minima respectively,iTo return
Wave train number；
(d) to first derivative signalIn the range of all points judged according to step (b)~(c), it is standby to obtain several
Select echo；
(e) alternative echo is judged, will be located at " step " scope at, i.e., sampled point be 230~255 points echo with
Reference curve is made comparisons.If being unsatisfactory for being more than 100~110, exclude；Otherwise, retain；
(f) to alternative echo " selected ", i.e., confidence level is calculated to each alternative echo, formula is：
(6)
(g) it is thing position echo to determine echo corresponding to maximum confidence.
As shown in Figure 12 ~ 14, the corresponding alternative echo of one group of △ and zero, i.e. echo after " roughing ", △ are represented in figure
Starting point, zero represents end point, the thing position echo range that vertical dashed lines labeled " selected " determines afterwards.Figure 12 is 15cm water level echos
Signal, thing position echo amplitude are less than noise thereafter.Can not accurate judgement thing position echo by peak-peak method；Under the echo
Drop is more or less the same than being less than 0.5 with the suppression ratio of itself " step ".It is dry according to setting " suppression ratio " parameter to exclude " step "
Disturb, there will necessarily be the problem of the two is excluded or can not be excluded simultaneously.With this patent institute extracting method, after reference curve
" roughing " noise larger with regard to amplitude can be excluded, only remain thing position echo.Figure 13 is 65cm water level echo signals, with tank bottom
The retort stand directly contacted is produced compared with strong jamming.Two alternative echoes are obtained after " roughing ".Because the width of interference echo is bigger,
Confidence value is smaller, is able to determine thing position echo.Figure 14 is the echo-signal of the long guided wave bar 650cm things positions of 8m, due to signal energy
Amount increases and reduced with thing position, therefore thing position echo amplitude is less than the noise level before being located at it, as seen from the figure, after " roughing "
Have to an echo, efficiently solve such case.
(4) propagation time calculates
Propagation time calculates the determination for containing thing position echo-bearing point and beginning point of reference, and echo-bearing point in thing position passes
Terminal between sowing time.
Existing method is using peak point as thing position echo-bearing point, the problem of fluctuation is big, precision is low, same liquid level be present
Under also can left and right skew 1 ~ 2 point.2 rank Lagrange interpolation are carried out to it equivalent to compensate for the problem of sample frequency is low, can
To improve precision.
To the characteristic point of echo, such as greatest gradient point, minimum slope point and using this 2 points of regional centers as border
Point is tested, and observes the linear case of not jljl position echo-bearing point.Wherein, central point calculation formula is：
(8)
In formula,midFor regional center point abscissa,yFor echo curve,iFor abscissa sampled point sequence number.
27 liquid levels have been randomly selected to 20 ~ 100cm liquid levels, have gathered one group of signal respectively, it is flat that 9 points of movements are carried out to signal
After equal filter preprocessing, with peak point, the rank Lagrange interpolation points of peak point 2, greatest gradient point, minimum slope point, central point
It is equal with thing position-linearly model that each echo-bearing point determines using least square fitting as thing position echo-bearing point
Measurement index of the square error as the linearity, as shown in table 3.
From the data in table 3, it can be seen that the root mean square of least square fitting is carried out by the use of minimum slope point as thing position echo-bearing point
Error is minimum, is secondly 2 rank Lagrange interpolation points of peak point for calculating the degree of accuracy highest of thing position.Clicked through with peak value
The purpose of the rank Lagrange interpolation of row 2 is identical, and 2 rank Lagrange are carried out to minimum slope point on the first derivative curve of signal
Interpolation, it can further improve precision.
The starting point in propagation time, which is theoretically, launches the square-wave pulse moment, still, in actual signal, exomonental
Point generally shake is severe, is flooded by noise, is not easy accurately to determine, the propagation time error so calculated is larger.
If starting point corresponds to the moment and ist 0 , the echo-bearing point of two known substance positions corresponds to the moment, that is, receives the time and be respectivelyt 1 ,t 2 , thing position is respectivelyh 1 ,h 2 , then the expression formula of linear fitMiddle parameter is：
(9)
From formula (9), level meter is calculated unrelated with start time.Therefore, the selection of starting point is defined by calculating fluctuation minimum
Then.
In the signal gathered, first reflection echo is fixation reflex echo, is produced by guided wave bar tie point, and it has
There is the characteristics of width is small, amplitude is big, rate of change is big.The straight line of different amplitudes is selected to intersect with the trailing edge, with linear interpolation
Method calculates intersection point as starting point is referred to, and calculates the time difference respectively, it is known that, amplitude is closer to pulse falling edge midpoint, time
Poor calculated value it is more stable.Therefore, it is more selected around at guided wave bar tie point reflection echo trailing edge midpoint, with where the point
Straight line intersects with the echo trailing edge, and linear interpolation obtains referring to starting point.
Determine with reference to after starting point and thing position echo-bearing point, can further calculate the propagation time：Propagation time=thing position
Echo-bearing point-refer to starting point.
(5) to calculating value filtering
In actual job site, due to the presence of various interference, even if thing position is constant, propagation time calculated value is still continuous
Change.First, gross error is eliminated by limit filtration, that is, it is random dry to exclude to limit propagation time calculated value fluctuating range
Disturb, lose the factors such as ripple caused by erroneous calculations result.By taking the echo-peak point of thing position as an example, generally at same thing position
1 ~ 2 point of meeting left and right skew, therefore can be using amplitude limit as 5.
Liquid level is constant, continuous acquisition 5000 group propagation time result of calculation, as shown in figure 15.It can be calculated the propagation time
Waving interval is [233.4419,234.6059], maximum offset 1.1640,1.5609cm, i.e., same thing is corresponded to through conversion
The measured value maximum offset of position is 1.5609cm.According to the computational methods of probability density, by propagation time sample fluctuation section
It is divided into 30 sections, the probability density on section is calculated after being ranked up to sample, as shown in figure 16.
As shown in Figure 16, the probability density function of propagation time sample is unsatisfactory for Gaussian Profile.Therefore, with linear filtering not
Noise can effectively be reduced.
Because medium filtering has special advantage in terms of abnormal data is excluded, in being carried out to propagation time sample sequence
Probability density function is calculated after value filtering again, and it is as shown in figure 17 to carry out Gauss curve fitting to it, it can be seen that by medium filtering
Sample probability density afterwards substantially conforms to Gaussian Profile, then carries out averagely reducing random error.Median average filter
The advantages of combining medium filtering and average filter, it is more easy in realization, median is carried out to multiple calculated value and averagely filtered
Ripple with go singular value, reduce random error.
Average filter pretreatment is moved to signal, limit filtration and median average filter are carried out to calculated value, with
Machine selects 30 groups of liquid level recorder liquid levels and corresponding propagation time calculated value, and the data obtained determines root mean square by least square fitting
Error is as shown in table 3.By contrast table 3 and table 4, help to reduce error after carrying out median average filter, improve meter
Calculate exactness accurately.
Guided wave formula radar levelmeter echo signal processing system and method based on first derivative（Application number：
201310534738.1 the applying date：On November 1st, 2013）Propose and 60 groups of median average filter is carried out to calculated value, can
To effectively reduce random error.But find in actual applications, 60 groups of median average filter will cause calculated value to refresh
It is too slow.For example, through actually detected, often performing a major cycle needs to spend 90ms, i.e., often gathers 1 signal of change, 1 thing position
The time of value.So liquid crystal, which refreshes 1 value, needs 90ms*60=5.4s, it is clear that can not quickly track the change of liquid level.Therefore, will
Median average filter window is decreased to 40 groups, is computed, and liquid crystal refresh time is 90ms*40=3.6s.
By above echo signal processing, the propagation time corresponding with a certain thing position has been obtained.Then, when this is propagated
Between substitute into by demarcate determine thing position and the functional relation between the propagation time, it is possible to calculate thing place value.
Calibration process is completed before level meter dispatches from the factory.Thing position and the functional relation between the propagation time are determined by demarcation
Formula.In theory, thing position and be linear relationship between the propagation time.Non-linear relation actually then be present.Therefore, carry out segmented line
Propertyization processing.For the guided wave bar of 1m length, the linearity from guided wave bar centre position to bar end is preferable；For long guided wave bar,
Partial linear degree after 1m is fine.Therefore, using the method for piece-wise linearization.In view of the convenience demand of practical operation,
Preferably carry out 3 point demarcation.For the processing method using minimum slope point as thing position echo-bearing point, this 3 points are selected in respectively
Within 30cm, [30cm, 35cm] ∪ [55cm, 60cm], and near the 100cm of end.The is used as by the use of and the 2nd point of fitting at the 1st point
1 section of coefficient；2nd point is used as the 2nd section of coefficient with the 3rd point of fitting.Two sections of separation is 30cm, is passed corresponding to this thing position
It can be roughly calculated to obtain by any point calibration point between sowing time, without extra increase calibration point.Determine expression formula, wherein,LFor thing position,tFor the propagation time,k,bTo demarcate relational expression coefficient,t 1 For time point of demarcating.
After writing SCM program, when actually measuring, the propagation time that echo signal processing is obtained substitutes into functional relation, so that it may
To calculate thing place value.
Claims (2)
1. a kind of guided wave formula radar levelmeter echo signal processing method based on first derivative and combination reference curve, including
(1) reference curve, (2) signal preprocessing are constructed, (3) thing position echo judges that (4) propagation time calculates, and (5) calculate thing position
Value；Concrete operations are：Storage in advance includes the signal of " step " part not being superimposed with thing position echo as reference curve, uses
Judge in follow-up thing position echo；9 moving average filtering pretreatments are carried out to echo-signal；Single order is carried out to filtered signal
Derivative calculations detect echo, and multi-parameter combination reference curve judges thing position echo, determine thing position echo-bearing point and with reference to starting
Point calculates the propagation time；Any 3 points of selection is entered rower and determined in restriction section, determines thing position-propagation time model；Finally, will
Propagation time substitutes into thing position and the functional relation between the propagation time, and thing place value is calculated；It is characterized in that：
For the guided wave formula radar levelmeter without synchronous trigger pulse, sampled because no synchronizing signal triggers ADC, therefore
It needs to be determined that first sampling point, guarantee collects correct signal segment；One complete echo-signal includes a square wave arteries and veins
Rush and positioned at some reflection echos thereafter；There is longer steady section before this echo-signal and next square-wave pulse, do not have
There is obvious echo, and square-wave pulse has precipitous rising edge and trailing edge；According to this feature of signal, in ADC interruption
Sampled point is judged in service subprogram, when it is determined that having collected the trailing edge of square-wave pulse, 1000 length after preservation
Data, the echo-signal section as subsequent treatment；" step " comprising surface of material, sensor itself in echo-signal section is dry
Disturb, the reflection echo, referred to as echo caused by factor such as noise；The specific processing step of echo-signal is as follows：
(1) reference curve is constructed
The 2 points of interference formed for " step " intrinsic in level meter signal：1) when thing position is less than 25cm, thing position echo amplitude
Less than noise level thereafter；2) " step " feature itself is approximate with thing position echo；Therefore, need to store in advance include not with thing
The signal of " step " part of position echo superposition judges as reference curve for follow-up thing position echo；
Tank is highly definite value, when guided wave formula radar levelmeter is arranged on tank deck, guided wave bar vertically downward, defines guided wave formula radar
Level meter flange undersurface to the distance of surface of material be thing position；Thing position is set to be appointing more than 70cm by increasing or decreasing material
Meaning value, then one group of echo-signal of random acquisition, that is, intercept and be not superimposed from starting point to comprising intrinsic in signal with other echoes
" step " part reflection echo signal signal segment；When Sampling starting point is square-wave pulse trailing edge, the part is starting point
It is a bit in 255~305 points to sampled point；When Sampling starting point is that square-wave pulse rising edge originates, the part may be expanded
Big is extremely a bit in 450~500 points from starting point to sampled point；
(2) 9 moving average filterings are carried out to echo-signal section, reduces noise, smooth shake；
(3) it is comprising effective reflection echo part to set echo seeking scope, is 1m for guided wave pole length, the Sampling starting point side of being
During wave impulse trailing edge, it is 230~500 points that sampled point, which can be set, and the guided wave bar tie point for eliminating section start fixation is reflected back
The influence of ripple, and reduce the length of unnecessary signal transacting；1 order derivative signal d of echo-signal section in the range of this is calculated,
Calculation formula after simplification is
In formula, f (x) is echo-signal section, xiFor the point on signal；
(4) 1 order derivative signal d is judged from the off, if d [n-1], d [n] contrary sign, and d [n] is more than 0, it is determined that n
For terminal end [i] and the starting point start [i+1] of next echo；If d [n-1], d [n] contrary sign, and d [n] is less than 0, and starting point is true
Calibrate will set, it is determined that n is peak point peak [i]；I represents echo sequence number；
(5) recorded the characteristic point of echo, i.e., after the starting point of echo, peak point, terminal, calculate the echo width w [i], one
The difference of order derivative maxima and minima, referred to as rate of change amp [i], and compared with preset value, less than preset value
Echo excludes, the echo of reservation alternately echo, can be with exclusive PCR echo, and the interference echo is random narrow spike arteries and veins
Punching, small size noise echo；The calculation formula of above-mentioned each characteristic parameter is：
W [i]=end [i]-start [i]
Amp [i]=d_max-d_min
In formula, d_max, d_min represent first derivative maxima and minima respectively, and i is echo sequence number；
(6) all points in the range of 1 order derivative signal d are judged according to step (4)~(5), obtains several alternative echoes；
(7) alternative echo is judged, the echo at " step " scope is made comparisons with reference curve, if being unsatisfactory for big
In 100 numerical value, then the echo is excluded；Otherwise, retain；
(8) confidence level confidence calculating is carried out to each alternative echo, formula is as follows：
Confidence [i]=0.6 × amp [i]+0.1 × data [peak [i]] -0.3 × w [i]
In formula, i is alternative echo sequence number, and data is echo-signal section, and peak is alternative echo-peak point；
(9) it is thing position echo to determine alternative echo corresponding to maximum confidence；
(10) minimum slope point is asked for thing position echo, and 2 rank Lagrange interpolation is carried out on first derivative curve, determine thing
Position echo-bearing point；It is more selected around at fixation reflex echo guided wave bar tie point reflection echo trailing edge midpoint, with the point
Place straight line intersects with the echo trailing edge, and linear interpolation obtains referring to starting point；Then the propagation time is calculated, during the propagation
Between=thing position echo-bearing point-refer to starting point；
(11) limit filtration is carried out to the propagation time, excludes erroneous calculations result caused by random disturbances reason, and preserve；
(12) to same thing position, the propagation time of more than 40 times for calculating preservation carries out median average filter, and end product is made
For the propagation time corresponding to the thing position；
The propagation time is substituted into by demarcating in the thing position of determination and the functional relation between the propagation time, is calculated
Thing place value；
In formula, L is thing position, and t is the propagation time, and k, b are to demarcate relational expression coefficient, t1For time point of demarcating.
2. a kind of guided wave formula radar levelmeter echo based on first derivative and combination reference curve as claimed in claim 1 is believed
Number processing method, it is characterised in that：
Including impulse sender, guided wave bar, equivalent time sampling circuit, signal conditioning circuit, the list based on MSP430F5418A
Piece machine system and liquid crystal display；Impulse waveform is produced by impulse sender, the signal is divided into two-way, all the way through preposition triggering electricity
Shaping is amplified on road, becomes that amplitude is larger, transmitting clock is delivered in forward position compared with the pulse signal trembled；Launch clock by launching day
Line sends periodic short pulse electromagnetic wave along guided wave bar；Electromagnetic wave reflects to form a series of on the interface of different medium
Echo-signal, equivalent time sampling circuit is sent to after being received by reception antenna；At the same time, time base circuit sends out another way pulse
Signal is mixed into frequency mixer with the echo impulse after tiny time postpones；Signal after equivalent time sampling becomes
Middle low frequency signal, single-chip microcomputer is sent to after conditioned circuit and is handled, result of calculation is by liquid crystal display；For level gauging
When, carried out according to the step of measuring afterwards is first demarcated；Dispatching from the factory, advance rower is determined, during demarcation, for the long guided wave bars of 1m, 3 thing positions
Point is selected within 30cm, near [30cm, 35cm] ∪ [55cm, 60cm], and end 100cm respectively；According to claim 1 institute
The signal transacting step stated obtain with the propagation time corresponding to this 3 thing sites, as nominal data, be divided into two sections of progress
Linear fit, by the use of the 1st point and the 2nd point of coefficient being fitted as the 1st section；2nd point is used as the 2nd section of coefficient with the 3rd point of fitting；
Two sections of separation is 30cm, and the propagation time corresponding to this thing position can be roughly calculated to obtain by any point calibration point, without
Extra increase calibration point；It is fitted obtained functional relation write-in SCM system.
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| CN112890859B (en) * | 2021-01-19 | 2024-01-09 | 广州多浦乐电子科技股份有限公司 | Data processing method and system based on ultrasonic signal feature vector |
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| CN113296066B (en) * | 2021-04-27 | 2023-06-23 | 北京锐达仪表有限公司 | Echo correction method, device, readable storage medium, electronic equipment and system |
| CN114764534A (en) * | 2022-03-30 | 2022-07-19 | 湖北文理学院 | Method, device, storage medium and device for measuring material energy consumption |
| CN117433606B (en) * | 2023-12-20 | 2024-03-19 | 成都易联易通科技有限责任公司 | Data denoising method and system for granary Internet of things |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN202267511U (en) * | 2011-06-14 | 2012-06-06 | 罗斯蒙特储罐雷达股份公司 | Guided wave radar level meter system propagating through multi-mode and provided with dielectric constant compensation |
| CN102661773A (en) * | 2012-05-15 | 2012-09-12 | 合肥工业大学 | System and method for processing echo signal of guided wave type radar level meter |
| CN103175587A (en) * | 2013-03-01 | 2013-06-26 | 电子科技大学 | Guided wave radar liquid indicator |
| CN103542911A (en) * | 2013-11-01 | 2014-01-29 | 合肥工业大学 | Guided wave radar level meter echo signal processing system and method based on first-order derivative |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7363812B2 (en) * | 2005-11-09 | 2008-04-29 | Rosemount Tank Radar Ab | Radar level gauge with variable transmission power |
-
2014
- 2014-11-21 CN CN201410671092.6A patent/CN104374447B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN202267511U (en) * | 2011-06-14 | 2012-06-06 | 罗斯蒙特储罐雷达股份公司 | Guided wave radar level meter system propagating through multi-mode and provided with dielectric constant compensation |
| CN102661773A (en) * | 2012-05-15 | 2012-09-12 | 合肥工业大学 | System and method for processing echo signal of guided wave type radar level meter |
| CN103175587A (en) * | 2013-03-01 | 2013-06-26 | 电子科技大学 | Guided wave radar liquid indicator |
| CN103542911A (en) * | 2013-11-01 | 2014-01-29 | 合肥工业大学 | Guided wave radar level meter echo signal processing system and method based on first-order derivative |
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