CN1632471A - Threshold adaptive processing method and device for vortex shedding flowmeter signal - Google Patents
Threshold adaptive processing method and device for vortex shedding flowmeter signal Download PDFInfo
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- CN1632471A CN1632471A CN 200410084746 CN200410084746A CN1632471A CN 1632471 A CN1632471 A CN 1632471A CN 200410084746 CN200410084746 CN 200410084746 CN 200410084746 A CN200410084746 A CN 200410084746A CN 1632471 A CN1632471 A CN 1632471A
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Abstract
This invention relates to valve value self-adapting process method and device of vortex flow meter. This invention gets the range express section of current signal frequency through the continuous monitoring by microprocessor. The dynamic adjusting window compares the up and down valve values to make the window comparer accurately capture and convert the signals of weak frequency with bad ratio of signal to noise into impulse frequency. The device in this invention comprises output window of the vortex flowmeter sensor, input window through front enlargement and filter unit connection window comparer, one input window of microprocessor unit and one output window through front enlargement and filter A/D conversion unit. And its output window is connected with the valve interface of connection window comparer through D/A conversion unit.
Description
Technical field
The present invention relates to a kind of threshold adaptive processing method and device of vortex shedding flowmeter signal.
Background technology
Vortex shedding flowmeter signal is meant signal frequency and the rapid-result direct ratio of measured stream, and tested flow velocity is the more little sensor output signal of low signal amplitude more.The linear range ability of the frequency of sort signal and flow velocity can reach 100: 1 in theory.But can stack various noises, particularly noise on the signal in the actual measurement environment tend to signal in identical frequency range, so the signal to noise ratio (S/N ratio) of the low more vortex flow sensors signal of flow velocity is just poor more.At present, there are two kinds on the method for signal frequency drawing: the one, adopt the window comparator of fixed threshold signal frequency to be caught and is converted to pulsed frequency; The 2nd, draw signal frequency by the digitized spectra analysis.First method is the interval interior a certain value of amplitude performance that the upper and lower threshold value of window comparator is fixed on most of signal frequency, and window comparator can accurately draw signal frequency under high definition case.Change greatlyyer but the amplitude performance of signal frequency is interval when the relatively poor low flow velocity of signal to noise ratio (S/N ratio), the window comparator of fixed threshold is difficult to accurate signal acquisition frequency, because the difficulty of low fluid-velocity survey makes range degree of enclosing only about 10: 1.The front-end system that has European patent (645258) in 2000 to amplify by segmentation filtering remedies the signal Processing defective of low flow velocity.Second method is to utilize spectrum analysis to determine signal frequency after signal digitalized, but has the relatively poor and low problem of frequency resolution of real-time.Want more than 27 seconds as Chinese patent 99101209.7 once complete digital spectrum analysis when the 10Hz signal frequency.
For achieving the above object, the present invention adopts following scheme:
A kind of threshold adaptive processing method of vortex shedding flowmeter signal, to the signal S0 of vortex street flowmeter sensor output behind preposition amplification and filter unit, adopt window comparator that pulse signal S1 is caught and be converted to signal S0 frequency, it is characterized in that adopting microprocessor unit signal S0 to be carried out data acquisition by the A/D converting unit, after the amplitude to signal S0 frequency shows interval A and monitors, the upper threshold value Vu and the lower threshold value Vd that dynamically adjust window comparator by the D/A converting unit show interval A with the amplitude that adapts to current demand signal S0 frequency, thereby make the frequency that reflects flow velocity among the signal S0 accurately be caught and be converted to the pulse signal S1 of respective frequencies by window comparator.
The work of treatment step of above-mentioned microprocessor unit is as follows:
Microprocessor unit shows the amplitude that the upper threshold value Vu and the lower threshold value of window comparator dynamically is adjusted at current demand signal S0 frequency in the interval A by the D/A converting unit, make upper threshold value Vu=K (Au-Ad)+Ad, lower threshold value Vd=-K (Au-Ad)-Ad, K is according to the flowmeter bore, fluid media (medium) is chosen in 0.1 ~ 0.9, can draw in the following ways and amplitude wherein shows interval A and Au and Ad: microprocessor unit carries out data acquisition by the A/D converting unit to signal S0, in time, draw maximum value point set Xp=(Xp1 greater than zero greater than vortex shedding flowmeter signal frequency maximum cycle T, Xp2, Xpn) and minus minimizing absolute value point set Xm=(Xm1, Xm2, Xmn), draw maximal value Xpmax and minimum value Xpmin among the point set Xp, draw maximal value Xmmax and minimum value Xmmin among the point set Xm, get value less among Xpmax and the Xmmax as higher limit Au, get value bigger among Xpmin and the Xmmin as lower limit Ad, the amplitude that draws current demand signal S0 frequency show interval A be Ad＜A＜Au and-Au＜A＜-Ad;
The device of the threshold adaptive processing method of above-mentioned vortex shedding flowmeter signal, comprise the input port of the delivery outlet of vortex street flowmeter sensor through preposition amplification and filter unit window comparator, it is characterized in that having A/D converting unit in input port of a microprocessor unit to connect the delivery outlet of preposition amplification and filter unit, and its delivery outlet connect the threshold value interface of window comparator through the D/A converting unit.
The present invention compared with prior art, have following remarkable advantage: the amplitude performance by continuous monitoring current demand signal frequency is interval, and make in the upper threshold value of window comparator and amplitude that lower threshold value the is adjusted at the current demand signal frequency adaptively performance interval, make window comparator also can catch and be converted to pulsed frequency exactly to the relatively poor signal frequency of signal to noise ratio (S/N ratio).Whole signal processing method was not only simple but also have adaptivity, correctness and rapidity characteristics that the height flow velocity signal is handled.Only at the A/D converter of original technical increase microprocessor and its import and export, equipment is more simple and reliable for the device that this method is used.
Description of drawings
Fig. 1 is one embodiment of the present of invention structural principle block diagram.
Fig. 2 is the signature tune line chart of Fig. 1 example.Wherein scheming a and scheming b is signal S0 curve and pulse signal S1 curve possible under the high velocity stream, and figure c and figure d are signal S0 curve and pulse signal S1 curve possible under the low-speed flow.
A preferred embodiment of the present invention such as following: referring to Fig. 1 and Fig. 2.
As follows for sensor output through the work of treatment step of preposition amplification and filtered signal S0:
Microprocessor unit 3 shows the amplitude that the upper threshold value Vu and the lower threshold value of window comparator dynamically is adjusted at current demand signal S0 frequency in the interval A by D/A converting unit 4, make upper threshold value Vu=K (Au-Ad)+Ad, lower threshold value Vd=-K (Au-Ad)-Ad, K is according to the flowmeter bore, fluid media (medium) is chosen in 0.1 ~ 0.9, can draw in the following ways and amplitude wherein shows interval A and Au and Ad: microprocessor unit 3 carries out data acquisition by 2 couples of signal S0 of A/D converting unit, in time, draw maximum value point set Xp=(Xp1 greater than zero greater than vortex shedding flowmeter signal frequency maximum cycle T, Xp2, Xpn) and minus minimizing absolute value point set Xm=(Xm1, Xm2, Xmn), draw maximal value Xpmax and minimum value Xpmin among the point set Xp, draw maximal value Xmmax and minimum value Xmmin among the point set Xm, get value less among Xpmax and the Xmmax as higher limit Au, get value bigger among Xpmin and the Xmmin as lower limit Ad, the amplitude that draws current demand signal S0 frequency show interval A be Ad＜A＜Au and-Au＜A＜-Ad;
Handle front signal S0 curve in typical case and handle back signal S1 curve for two kinds and be shown among Fig. 2.
The device that present embodiment adopts is: the delivery outlet of vortex street flowmeter sensor 1 is through the input port of preposition amplification and filter unit 2 window comparators, the A/D converting unit in the input port 4 preposition amplifications of connection of a microprocessor unit 6 and the delivery outlet of filter unit 2 are arranged, and its delivery outlet connects the threshold value interface of window comparators 3 through D/A converting unit 5.
Claims (3)
1. the threshold adaptive processing method of a vortex shedding flowmeter signal, to the signal S0 of vortex street flowmeter sensor (1) output behind preposition amplification and filter unit (2), adopt window comparator (3) that pulse signal S1 is caught and be converted to signal S0 frequency, it is characterized in that adopting microprocessor unit (6) signal S0 to be carried out data acquisition by A/D converting unit (4), after the amplitude to signal S0 frequency shows interval A and monitors, the upper threshold value Vu and the lower threshold value Vd that dynamically adjust window comparator (3) by D/A converting unit (5) are interval with the amplitude performance that adapts to current demand signal S0 frequency, thereby make the frequency that reflects flow velocity among the signal S0 accurately be caught and be converted to the pulse signal S1 of respective frequencies by window comparator (3).
2. the threshold adaptive processing method of vortex shedding flowmeter signal according to claim 1, it is characterized in that microprocessor unit (3) shows the amplitude that the upper threshold value Vu and the lower threshold value of window comparator dynamically is adjusted at current demand signal S0 frequency in the interval A by D/A converting unit (4), make upper threshold value Vu=K (Au-Ad)+Ad, lower threshold value Vd=-K (Au-Ad)-Ad, K is according to the flowmeter bore, fluid media (medium) is chosen in 0.1 ~ 0.9, can draw in the following ways and amplitude wherein shows interval A and Au and Ad: microprocessor unit (3) carries out data acquisition by A/D converting unit (2) to signal S0, in time, draw maximum value point set Xp=(Xp1 greater than zero greater than vortex shedding flowmeter signal frequency maximum cycle T, Xp2, Xpn) and minus minimizing absolute value point set Xm=(Xm1, Xm2, Xmn), draw maximal value Xpmax and minimum value Xpmin among the point set Xp, draw maximal value Xmmax and minimum value Xmmin among the point set Xm, get value less among Xpmax and the Xmmax as higher limit Au, get value bigger among Xpmin and the Xmmin as lower limit Ad, the amplitude that draws current demand signal S0 frequency show interval A be Ad＜A＜Au-and-Au＜A＜-Ad;
3. device that is used for the threshold adaptive processing method of the described vortex shedding flowmeter signal of claim 1, comprise the input port of the delivery outlet of vortex street flowmeter sensor (1) through preposition amplification and filter unit (2) window comparator (3), it is characterized in that the A/D converting unit in input port (4) the preposition amplification of connection of a microprocessor unit (6) and the delivery outlet of filter unit (2) are arranged, and its delivery outlet connects the threshold value interface of window comparator (3) through D/A converting unit (5).
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| CN 200410084746 CN1632471A (en) | 2004-12-02 | 2004-12-02 | Threshold adaptive processing method and device for vortex shedding flowmeter signal |
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| CN 200410084746 CN1632471A (en) | 2004-12-02 | 2004-12-02 | Threshold adaptive processing method and device for vortex shedding flowmeter signal |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110166054A (en) * | 2019-05-08 | 2019-08-23 | 上海大学 | A kind of sigma-delta modulator of not incoming clock signal |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110166054A (en) * | 2019-05-08 | 2019-08-23 | 上海大学 | A kind of sigma-delta modulator of not incoming clock signal |
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