CN1025760C - Microcomputerized on-line real-time two-phase current high-speed measuring correlator - Google Patents

Abstract

The present invention belongs to a speed measurement device which utilizes a Z8671 type single-chip microcomputer and adopts a sampling interface circuit and special signal storage and data treatment methods to obtain a two-phase flow rapid measurement correlator using the single-chip microcomputer as a core at one fling, and the sampling interface circuit is connected to the two high-bit port wires of a parallel port of the single-chip microcomputer through two wires from an upstream polarity signal collection position and a downstream polarity signal collection position. Compared with hardware type correlators, the measurement correlator has the advantages of flexible use and low cost. Compared with other software type correlators, the data processing time (only parts per thousand) of the measurement correlator is notably shortened. The measurement correlator has high real-time characteristic, and is capable of widely satisfying the measurement requirements of two-phase flow.

Description

Microcomputerized on-line real-time two-phase current high-speed measuring correlator

The invention belongs to speed measuring device.

Many industrial processes regular meeting runs into the mensuration of gas-solid, liquid-solid and biphase gas and liquid flow flow.The conventional determining method causes that because of generally there being resistance piece fluid pressure loss, resistance piece wearing and tearing, corrosion are to cause to block and the precision reduction.Though electromagnetic flowmeter can unobstructedly be measured, it also is only limited to having the Medium Measurement of electric conductivity.

The simple crosscorrelation flowmeter can adopt the sensor of multiple principle to obtain flowing noise signal (condenser type, ultrasonic sensor etc.), realizes unobstructed or non-cpntact measurement, thereby has avoided above-mentioned defective.

Measuring two-phase flow speed and flow with correlator, is the upstream and downstream signal x(t that is constantly gathered in difference with at a distance of two identical sensors of certain distance L), y(t) to certainly exist certain correlativity or proximity principle be foundation.If the upstream and downstream signal is respectively x(t), y(t), then their related function should be:

In the formula: τ-fluid flowing time

The t-acquired signal constantly

T-acquired signal required time

Obviously, work as R _Xy(τ) peak value R appears _m(τ ₀) time, x(t) and y(t) should be the most close, this moment fluid flowing time τ=τ ₀Be fluid flow through the required transit time of distance L (seeing Fig. 1 b).Thereby obtain flow velocity V=L/ τ ₀, flow Q=VA(A-cross-section of pipeline is long-pending).

Can only get finite value the integral time in (1) formula in actual applications, at this moment:

R _xy（τ）＝ 1/(T) ∫ ^T _ox（t-τ）y（t）dt （2）

Fig. 1 a is simple crosscorrelation flow measurement principle schematic.Among the figure: 1-two-phase flow medium, the 2-medium pipeline, the 3-sensor, other are the program figure that rectifies.

For simplifying correlation computations, with x(t), y(t) carry out 1 bit quantization, polar signal X(i), Y(i), its related function is:

$R_{\mathrm{X\; Y}}\mathrm{(\; j\; )\; =}\frac{1}{N}\underset{\mathrm{i\; =\; 1}}{\overset{N}{\mathrm{\Σ}}}\mathrm{X\; (\; i\; )\; Y\; (\; i\; +\; j\; )\; (\; 3\; )}$

In the formula: the i-sequence number of taking a sample

J-inscribes the five equilibrium delay value of correlation correspondence when different

N-signal averaging number of times

Can prove, as signal x(t), y(t) when being the Gaussian signal, polar signal X(i), Y(i) related function and original signal x(t), y(t) the peak of related function overlap.Calculate on the historical facts or anecdotes border is to seek R _XY(j) the pairing delay value j=n of maximal value (being peak value), thus τ obtained ₀=n △ (△-sampling period).

Simple crosscorrelation two-phase flow measurement method needs a large amount of acquired signal are carried out data processing.The correlator that adopts has two kinds at present: with the large scale integrated circuit hardware type correlator of core, though deal with data is fast, and very flexible, cost is too high.In contrast, be the software formula correlator of core with common microprocessor or single-chip microcomputer, though flexibly, cost is low, deal with data takes oversize (the situation processing time reaches several seconds preferably at present), is difficult to satisfy the requirement of online in real time two-phase flow measurement.The microcomputerized on-line real-time two-phase that this kind formed with sensor, single-chip microcomputer, display, keyboard, interface circuit and sampling holder is measured correlator, and why real-time performance is relatively poor, main cause or because of its type select improper, or because of its sampling interface power station connection improper, making signals collecting and depositing fail to resemble per in regular turn eight pairs that back of the present invention narrates is stored in each register, certainly also just can not when correlation value calculation, finish eight couples of X, Y-signal simultaneously relatively by an xor operation.Existing in addition software formula correlator is when data processing, the identical correlation number of polarity adopted add up one by one and mode that correlation peaks is relatively sought in pointwise prolongs data processing time (to see MSBeck greatly, Correlation in Instruments:Crosscorrelation Flowmeters, JPhys.E:Sci.Instrum., Vol.14, PP7-19, No1,1981.Xu Lingan, related flow measurement technology, publishing house of University Of Tianjin, 1988.J·Coulthard，The Principle of Ultrasonic Crosscorrelation Flowmetering，Measurement and Control，Vol.8，PP·65-70，February，1975）。

Purpose of the present invention just is significantly to shorten the data processing time of software formula correlator, improves real-time usefulness to satisfy the two-phase flow measurement requirement.

Core content of the present invention is to adopt Z ₈₆₇₁The type single-chip microcomputer, and adopt by collection place of upstream and downstream polar signal and receive sampling interface circuit on high two mouth lines of a parallel port of single-chip microcomputer with two lines, thereby make the collection of signal and deposit and to utilize the characteristics that a plurality of registers in the single-chip microcomputer can serial shift, in signal acquisition process, make each memory cell store 8 acquired signal in regular turn.Promptly at first the polar signal XY of synchronization is taken into register A by a parallel port, subsequently register A and register B, C is constituted series system respectively, make that signal X moves in the B, signal Y moves in the C and (sees Fig. 2 a).When the signal XY that deposits in regular turn in the BC reaches 8 respectively, then the content among the BC is delivered to XY signal storage area separately.After this, whenever get XY signal all according to last method with content among the BC in regular turn to XY separately storage area transfer once, until desired signal all being adopted into (see Fig. 2 bd, among the figure, b is the X storage area, and d is the Y storage area).This just makes the R subsequently _XY(j) calculating and comparison can be finished 8 couples of XY relatively simultaneously by an xor operation.As R(5) form of calculation can be expressed as:

In the formula+the expression XOR

By said process as seen, 8 deposit data in a register, are finished in sampling process, do not needed the extra processing time.An xor operation can be realized the comparison of 8 X, Y sampled value, improved relative efficiency, simultaneously, internal memory, the transmission of the data between external memory number of times required when making correlation computations reduce significantly, alleviated because the common microprocessor memory size is little the affected degree of the real-time of its deal with data.

After polar was handled, signal was " 0 " or " 1 ", and the product of signal becomes comparison, and integration becomes and adds up.If the N point of formula (3) relatively in, the signal polarity that has P to order is identical, the signal polarity that q is ordered is opposite, p+q=N, so polarity correlation function can be expressed as following form of calculation:

R _XY（j）＝ 1/(N) （p-q） （4）

R _XY（j）＝ 1/(N) （2p-N） （5）

As seen, can ask correlation by formula (5) replacement formula (3), the point that the polarity that only adds up is identical, and opposite polarity point is not subtracted, can reduce calculated amount.Software formula correlator can carry out the polarity similarities and differences relatively by the XOR instruction of computing machine, and the identical polar comparative result is " 0 ", and the opposed polarity comparative result is " 1 ".

The number that the identical result of polarity " 0 " relatively may appear in per 8 couples of XY when the inventor utilized the N point relatively has the characteristics of certain rule, deposit it in single-chip microcomputer (seeing Table 1) with form, thus make per 8 couples of X, Y polarity same number add up that becoming once tables look-up can get.In addition, the inventor uses dichotomizing search related function peak method to substitute pointwise then and relatively seeks peak value also with first coarse scanning, promptly in certain peak value searching scope, determines starting point j _o, terminal point j _e, with j _oTo j _eBy certain point number ω five equilibrium, calculate the correlation at each separation place, find out the wherein pairing delay value j of maximal value ₁, subsequently with j ₁For obtaining R(j respectively in the center ₁+ (ω)/2), R(j ₁-(ω)/2), R(j compared ₁), R(j ₁+ (ω)/2), R(j ₁-(ω)/2), find out the pairing delay value of maximal value among the three

Table 1 scale-of-two is arranged

Two systems are arranged and are contained the zero number

0000 0000 8

0000 0001 7

0000 0010 7

1111 1101 1

1111 1110 1

1111 1111 0

j ₂, again with j ₂For obtaining R(j respectively in the center ₂+ (ω)/(22)), R(j ₂-(ω)/(22)), R(j compared ₂), R(j ₂+ (ω)/(22)), R(j ₂-(ω)/(22)), find out the wherein pairing delay value j of maximal value ₃Or the like, and the like, till obtaining the pairing delay value j=n of peak value that resolution is 1 sampling interval.For example getting the peak value searching scope is that the correlator measurement window is 127 points, supposes to get j _oIt is variable that=20(measures starting point), je=148, with 20～148 every ω=16 separation once, Bing Hang calculating R(36 then), R(52), R(68), R(84), R(100), R(116), R(132), find out the wherein pairing delay value j of maximal value ₁, calculate R(j ₁+ 8), R(j ₁-8), compare R(j ₁), R(j ₁+ 8), R(j ₁-8), find out the wherein delay value j of maximal value correspondence ₂, calculate R(j ₂+ 4), R(j ₂-4) ... or the like, up to obtaining the delay value j=n that resolution is the peak value correspondence of 1 sampling interval, calculate τ o=n △, V=L/ τ o subsequently, Q=VA.

Because the present invention has adopted above-mentioned measure, makes the present invention compared with prior art, its data processing time shortens greatly, and real-time performance significantly improves.

Table 2 is the inventor with Z ₈₆₇₁Single-chip microcomputer (crystal oscillator is 7.3728 megahertzes) is 127 points for the software correlator of core in measurement window, the real-time measurement result that is obtained when being instrument with the binary sequence pseudo random signal generator.Average per second measurement number of times comprises the sampling time in the table.As when the N=256 (the common value of getting of prior art), one-shot measurement is 42 milliseconds, removes the sampling time, and data processing only is 10 milliseconds.

Table 2 real-time performance testing result

Average per second is measured inferior

Integration (branch) number of times of counting the test duration

Number (inferior/second)

N＝256 4 5712 23.8

N＝512 5 4080 13.6

N＝1024 8 3672 7.6

N＝1280 7 2856 6.8

Claims (2)

1, a kind of microcomputerized on-line real-time two-phase current high-speed measuring correlator of being made up of sensor, single-chip microcomputer, display, keyboard, interface circuit and sampling holder is characterized in that:

A. said single-chip microcomputer is the Z2871 single-chip microcomputer;

B. its sampling interface circuit is to be received from the upstream and downstream signals collecting on high two mouth lines of a parallel port of single-chip microcomputer by two lines.

2, a kind of measuring method of microcomputerized on-line real-time two-phase current high-speed measuring correlator, it comprises gathers and deposits signal, calculates and comparison correlation R _XY(j), determine R _XY(j) peak value and corresponding delay value j=n calculate transit time τ ₀=n △ (△ is the sampling period), flow velocity V=L/ τ ₀(L is the fluid flow path distance) and flow Q=VA(A are that cross-section of pipeline is long-pending), it is characterized in that:

A. said collection and deposit signal and be meant and utilize Z ₈₆₇₁The characteristics that a plurality of registers can serial shift in the single-chip microcomputer, in signal acquisition process, make each memory cell store 8 signals in regular turn, promptly at first the polar signal XY of synchronization is taken into register A by a parallel port, subsequently with register A and register B, C constitutes series system respectively, signal X is moved in the B, signal Y moves in the C, work as B, when the signal XY that deposits in regular turn in the C reaches 8 respectively, then with B, content is delivered to X among the C, Y storage area separately, after this, whenever get X one time, Y-signal all according to last method with B, content is in regular turn to X among the C, Y storage area separately transfers once, until desired signal is all adopted into;

B. said calculating and comparison R _XY(j) be meant the comparison of finishing 8 couples of X, Y-signal by xor operation simultaneously, and utilize 8 numbers that may occur the identical result of polarity " 0 " relatively the time that the characteristics of certain rule are arranged, deposit in the single-chip microcomputer with form, make adding up to become once and tabling look-up of per 8 couples of X, Y polarity same number;

C. said definite R _XY(j) peak value and corresponding delay value j=n are meant first coarse scanning, use the alternative pointwise of method of dichotomizing search related function peak value relatively to seek peak value then, promptly in certain peak value searching scope, determine starting point jo, terminal point je, jo to je is pressed certain point number ω five equilibrium, calculate the correlation at each separation place, find out the wherein pairing delay value j of maximal value ₁, j subsequently ₁Be the center, obtain R(j respectively ₁+ (ω)/2), R(j ₁-(ω)/2), R(j compared again ₁), R(j ₁+ (ω)/2), R(j ₁-(ω)/2), find out the pairing delay value j of maximal value among the three ₂, again with j ₂Be center calculation R(j ₂+ (ω)/(22)), R(j ₂-(ω)/(22)), R(j compared ₂) R(j ₂+ (ω)/(22)), R(j ₂-(ω)/(22)), find out the pairing delay value j of maximal value among the three ₃Or the like, the rest may be inferred, until obtaining the pairing delay value j=n of peak value that resolution is 1 sampling interval.

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