An Algorithm for Measuring Flow of Ultrasonic Gas Meter
A technology of gas meter and ultrasonic wave, which is applied in the measurement of flow/mass flow, liquid/fluid solid measurement, calculation, etc., and can solve the problem of increasing the amount of calculation
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Embodiment 1
[0073] Such as Figure 1 to Figure 4 The flow measurement algorithm of an ultrasonic gas meter shown includes the following steps:
[0074] (A) Input the up flight signal and the down flight signal, and perform Fourier transform on the up flight signal and the down flight signal respectively;
[0075] The purpose of Fourier transform is to convert the signal in the original time domain to the wavenumber domain, obtain the respective frequency spectrum, and provide convenience for the calculation of the cross-correlation curve.
[0076] (B) Calculate the frequency spectrum of the cross-correlation curve based on the Fourier transform results of the upper flight signal and the lower flight signal;
[0077] The convolution process of the cross-correlation curve in the time domain is equivalent to the product process in the wavenumber domain. The purpose of the cross-correlation curve calculation is to use the uncorrelated relationship between the Gaussian white noise generated by the tr...
Embodiment 2
[0084] On the basis of Example 1, in step (A), the flying signal s 1 (n) and off-air signal s 2 (n) After Fourier transform, F 1 (k) and F 2 (k), where:
[0085]
[0086]
[0087] Among them, k=0,1,2,...,N-1,n=0,1,2,...,N-1, N is the length of the expanded sequence, and j is the imaginary unit.
[0088] After that, in step (B), the frequency spectrum of the cross-correlation curve F(k)=F 1 (k)·F 2 (k).
[0089] In step (C), the correlation curve R dc (k) Calculated by the following formula:
[0090]
[0091] Such as figure 2 As shown, the peak point k is obtained on the correlation curve, and two points k-1 and k+1 are respectively selected on both sides adjacent to the peak point k. After the three points are determined, the estimated value of the model one The calculation formula is:
[0092]
[0093] In step (D), the imaginary part taken after Hilbert transform is performed on the frequency spectrum F(k) of the cross-correlation curve Obtained by the following formula:
[0094] H(...
Embodiment 3
[0128] On the basis of Example 1 and Example 2, the specific values are brought into the above formula for calculation.
[0129] Zero air volume situation: In the case of zero air volume, there are 421 sets of 117870 high temperature (55°) data, 13076 sets of low temperature (-15°) data, and 432 sets of 120960 normal temperature (20°) data. Under the three temperature conditions, the estimated average time difference calculated by the formula is -0.3062ns, 0.1763ns and 0.1187ns, and the mean square error is 0.4667ns, 0.6078ns and 0.2769ns. Such as Figure 5 As shown, in the three temperature conditions, the average time difference is close to 0 ns, which has strong consistency. The mean square error is slightly enlarged in the high and low temperature conditions, but the overall error is within ±2ns.
[0130] Micro air volume situation: the average air volume at room temperature is 13L / h, there is air volume disturbance, a total of 100 sets of 28,000 data, respectively, the esti...
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