JP2009236595A - Ultrasonic flow measuring method and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reflection type ultrasonic flowmeter and a flow measuring method using a correlation method capable of highly accurate measurements without being affected by Fourier uncertainty. <P>SOLUTION: The reflection type ultrasonic flowmeter and the flow measuring method using a correlation method have steps for performing wavelet transformation on reference waves and search waves instead of Fourier transformation and comparing wavelet coefficients to determine the correlation between the reference waves and the search waves. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to an ultrasonic flow velocity distribution and a flow meter that measure flow velocity distribution and flow rate of the fluid using ultrasonic pulses, and in particular, non-contact the flow velocity distribution and flow rate of various fluids including relatively clean fluid. The present invention relates to a reflection type ultrasonic flow rate measurement method and program using a measurable correlation method.

There are techniques disclosed in Patent Document 1, Patent Document 2, and Patent Document 3 as reflection type ultrasonic flowmeters using the correlation method.
JP 2003-344131 A JP 2004-333260 A JP2005-208068

  The reflection type ultrasonic flowmeter using the correlation method finds the echo signal from the same reflector for different pulses from the correlation of the waveform, calculates the velocity of the reflector from the time difference, and uses this velocity to distribute the flow velocity It measures the flow rate.

  FIG. 6 shows a measurement form of the reflection type ultrasonic flowmeter. An ultrasonic pulse is incident on the fluid in the pipe 20 a plurality of times from the transducer 17 and the echo is analyzed to obtain a flow velocity distribution along the measurement line (ML).

  FIG. 7 illustrates the relationship between the ultrasonic beam 30 incident from the transducer 17 and the reflector 40 such as bubbles in the fluid. Since the reflector 40 moves along the flow, assuming that a position where a certain ultrasonic pulse collides is A, the subsequent ultrasonic pulse collides downstream as B.

For this reason, since the distance from the transducer 17 is different, a phenomenon occurs in which the time difference between the ultrasonic pulse as the incident wave and the ultrasonic echo as the reception wave differs depending on the pulse as shown in FIG. In FIG. 8, the reflector 40 is displaced by Δx between the ultrasonic pulse oscillated at time t ₀ and the pulse oscillated after Δt. This is observed as Δτ in the received waveform.

From the above, the distance x from the transducer 17 and the flow velocity u (x) at that position can be obtained from the equations (1) and (2).
Here, τ is the time from when the ultrasonic pulse is oscillated until the reflected wave is received, and c is the velocity of the ultrasonic wave.

  Thus, if the echo signal from the same reflector can be specified, the speed of the reflector, that is, the flow velocity can be obtained from the time difference. In order to search for an echo from this same reflector, a waveform in a specific time zone is cut out from the echo signal as a reference wave, and an arbitrary waveform (search for the same width in time as the reference wave) is searched from other parts of the echo signal. The reflection type ultrasonic flowmeter using the autocorrelation method finds the reflected wave from the same reflector by cutting out the wave) and calculating the correlation.

  A basic configuration of a reflection type ultrasonic flowmeter using the correlation method is as shown in FIG. The trigger transmission board 12, the pulsar receiver 14 which is an ultrasonic transmission / reception means, the transducer 17, the AD converter 15 which samples the received ultrasonic echo signal and converts it into a digital signal, the AD converter memory 22, the digitized super It comprises a personal computer (personal computer) 11 which is a signal processing means for processing a sound wave echo signal to calculate a flow velocity distribution and a flow rate.

First, the trigger transmission board 12 generates a trigger signal, and the pulsar receiver 14 generates an electric pulse signal according to the trigger signal. The transducer 17 converts this electric pulse signal into an ultrasonic pulse and oscillates.

The trigger signal is also transmitted to the AD converter 15 for synchronization.

  The transducer 17 inputs an ultrasonic pulse beam into the metal pipe 20 and receives an ultrasonic echo signal that is a reflected wave from a reflector mixed in the measurement target fluid after the ultrasonic pulse is oscillated. The received ultrasonic echo signal is sent from the transducer 17 to the AD converter 15 via the pulser receiver 14. The AD converter 15 performs sampling in synchronization with the trigger signal, and transmits the converted digital echo signal to the personal computer 11.

  The digital ultrasonic echo signal converted by the AD converter is processed by the personal computer 11 as signal processing means, and the flow velocity distribution and the flow rate are obtained.

  Now, in the reflection type ultrasonic flowmeter using the correlation method, the correlation coefficient is calculated and the correlation between the reference wave and the search wave is determined to determine whether the reference wave and the search wave have the same waveform. However, the mathematical meaning is equivalent to the Fourier transform of the reference wave and the search wave, respectively, and the size of the frequency band to be encoded is compared, and it has the uncertainty problem that the Fourier transform has. ing.

FIG. 10 illustrates the extraction of the reference wave and the search wave. Since both the reference wave and the search wave are waveforms with limited time intervals, the window function is multiplied as shown in Expression (3) in this Fourier transform. Do it.
ω (x−b) is a window function used when analyzing the vicinity of x = b.

However, in the method of performing Fourier transform by multiplying by a window function, a precision limit based on the uncertainty principle of Fourier analysis occurs.

  The present invention aims to provide a highly accurate measurement technique without being influenced by the uncertainty principle of Fourier analysis, and performs correlation between a reference wave and a search wave by using a wavelet transform. It is.

That is, the present invention is as follows (1)
A trigger transmission step for outputting a trigger signal;
An ultrasonic pulse oscillation step of oscillating an ultrasonic pulse a plurality of times toward the measurement line of the fluid flowing in the pipe by the trigger signal;
An ultrasonic pulse receiving step for receiving a reflected wave of an ultrasonic pulse by a reflector in the fluid and converting it to an ultrasonic echo signal;
AD conversion step for analog-digital conversion and storing the ultrasonic echo signal;
A correlation calculation step for extracting a reference wave and a search wave from the stored digital ultrasonic echo signal and calculating an autocorrelation;
A phase identifying step that considers the reflected wave from the same reflector when the correlation between the reference wave and the search wave is equal to or greater than a certain value;
A phase difference calculating step of calculating a phase difference between the reference wave and the search wave specified by the phase specifying step;
A velocity calculating step for calculating the velocity of the ultrasonic reflector along the measurement line from the phase difference obtained by the phase difference calculating step;
A position specifying step of specifying a position of a reflector on a measurement line from a time difference between the ultrasonic pulse and an ultrasonic echo with respect to the ultrasonic pulse;
An ultrasonic flow velocity distribution measuring method comprising a flow velocity distribution calculating step of calculating a flow velocity distribution from the calculated velocity and position of the ultrasonic reflector,
The correlation calculation step includes:
A wavelet transform step for wavelet transforming each of the reference wave and the search wave;
Comparing wavelet coefficients for the same wavelet function in the wavelet transformed reference wave and search wave;
A step of determining a correlation between the reference wave and the search wave based on the comparison data,
Ultrasonic velocity distribution measurement method (2)
A trigger transmission step for outputting a trigger signal, and an ultrasonic pulse oscillation step for oscillating an ultrasonic pulse a plurality of times toward a measurement line of a fluid flowing in the pipe by the trigger signal;
An ultrasonic pulse receiving step for receiving a reflected wave of an ultrasonic pulse by a reflector in the fluid and converting it to an ultrasonic echo signal;
AD conversion step for analog-digital conversion and storing the ultrasonic echo signal;
A correlation calculation step of extracting a reference wave and a search wave from the stored digital ultrasonic echo signal and calculating an autocorrelation;
A phase identifying step that considers the reflected wave from the same reflector when the correlation between the reference wave and the search wave is equal to or greater than a certain value;
A phase difference calculating step of calculating a phase difference between the reference wave and the search wave specified by the phase specifying step;
The velocity calculation step for calculating the velocity of the ultrasonic reflector along the measurement line from the phase difference obtained by the phase difference calculation step, and the position of the reflector on the measurement line is specified from the time difference between the ultrasonic pulse and the ultrasonic echo corresponding thereto. An ultrasonic flow rate measuring method for calculating a flow rate from a flow rate distribution calculating step and a flow rate distribution calculating step for calculating a flow velocity distribution from the position specifying step, the calculated velocity and position of the ultrasonic reflector,
The correlation calculation step includes:
A wavelet transform step for wavelet transforming each of the reference wave and the search wave;
Comparing wavelet coefficients for the same wavelet function in the wavelet transformed reference wave and search wave;
A step of determining a correlation between the reference wave and the search wave based on the comparison data,
Ultrasonic flow measurement method (3)
A trigger transmission step for outputting a trigger signal;
An ultrasonic pulse oscillation step of oscillating an ultrasonic pulse a plurality of times toward the measurement line of the fluid flowing in the pipe by the trigger signal;
An ultrasonic pulse receiving step for receiving a reflected wave of an ultrasonic pulse by a reflector in the fluid and converting it to an ultrasonic echo signal;
AD conversion step for analog-digital conversion and storing the ultrasonic echo signal;
A correlation calculation step for extracting a reference wave and a search wave from the stored digital ultrasonic echo signal and calculating an autocorrelation;
A phase identifying step that considers the reflected wave from the same reflector when the correlation between the reference wave and the search wave is equal to or greater than a certain value;
A phase difference calculating step of calculating a phase difference between the reference wave and the search wave specified by the phase specifying step;
A velocity calculating step for calculating the velocity of the ultrasonic reflector along the measurement line from the phase difference obtained by the phase difference calculating step;
A position specifying step of specifying a position of a reflector on a measurement line from a time difference between the ultrasonic pulse and an ultrasonic echo with respect to the ultrasonic pulse;
An ultrasonic flow velocity distribution measurement program comprising a flow velocity distribution calculation step for calculating a flow velocity distribution from the calculated velocity and position of the ultrasonic reflector,
The correlation calculation step includes:
A wavelet transform step for wavelet transforming each of the reference wave and the search wave;
Comparing wavelet coefficients for the same wavelet function in the wavelet transformed reference wave and search wave;
A step of determining a correlation between the reference wave and the search wave based on the comparison data,
Ultrasonic velocity distribution measurement program (4)
A trigger transmission step for outputting a trigger signal, and an ultrasonic pulse oscillation step for oscillating an ultrasonic pulse a plurality of times toward a measurement line of a fluid flowing in the pipe by the trigger signal;
An ultrasonic pulse receiving step for receiving a reflected wave of an ultrasonic pulse by a reflector in the fluid and converting it to an ultrasonic echo signal;
AD conversion step for analog-digital conversion and storing the ultrasonic echo signal;
A correlation calculation step of extracting a reference wave and a search wave from the stored digital ultrasonic echo signal and calculating an autocorrelation;
A phase identifying step that considers the reflected wave from the same reflector when the correlation between the reference wave and the search wave is equal to or greater than a certain value;
A phase difference calculating step for calculating a phase difference between the reference wave and the search wave specified by the phase specifying step;
The velocity calculation step for calculating the velocity of the ultrasonic reflector along the measurement line from the phase difference obtained by the phase difference calculation step, and the position of the reflector on the measurement line is determined from the time difference between the ultrasonic pulse and the ultrasonic echo corresponding thereto. An ultrasonic flow rate measurement program for calculating a flow rate from a flow rate distribution calculating step and a flow rate distribution calculating step for calculating a flow rate distribution from the position specifying step, the calculated velocity and position of the ultrasonic reflector,
The correlation calculation step includes:
A wavelet transform step for wavelet transforming each of the reference wave and the search wave;
Comparing wavelet coefficients for the same wavelet function in the wavelet transformed reference wave and search wave;
A step of determining a correlation between the reference wave and the search wave based on the comparison data,
Ultrasonic flow measurement program

  According to the present invention, highly accurate measurement can be performed without being affected by the uncertainty principle of Fourier analysis.

An embodiment of an ultrasonic flow velocity distribution and a flow meter according to the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a measurement system schematically showing an embodiment of an ultrasonic flow velocity distribution and a flow meter according to the present invention.

The ultrasonic flow velocity distribution and flow meter 10 is obtained by adding a fluid flow velocity distribution and flow rate measurement function to a personal computer (personal computer) 11 as a control means and a signal processing means.

The ultrasonic flow velocity distribution and flow meter 10 includes a personal computer 11, a trigger oscillation board 12 as trigger oscillation means for outputting a trigger signal, a pulsar receiver 14 and a transducer 17 as ultrasonic oscillation means. The pulsar receiver 14 is connected to the trigger oscillation board 12 via the connector cable 13, and the transducer 17 is connected to the pulsar receiver 14 via the connector cable 16. The transducer 17 and pulsar receiver 14 also serve as ultrasonic pulse receiving means.

Further, the ultrasonic flow velocity distribution and the flow meter 10 has an AD converter 15. The trigger oscillation board 12 controls signal transmission / reception timing of the pulsar receiver 14 and the AD converter 15, and the output waveform of the trigger signal can be arbitrarily set by a preset software program.

The pulsar receiver 14 receives the trigger signal from the trigger oscillation board 12 and outputs an ultrasonic pulse oscillation signal to the transducer 17. The pulsar receiver 14 incorporates a digital synthesizer, can output an ultrasonic pulse oscillation signal from 50 kHz to 20 MHz, and can correspond to the transducer 17 having various oscillation frequency characteristics.

On the other hand, the transducer 17 converts the ultrasonic pulse oscillation signal output from the pulsar receiver 14 into an ultrasonic pulse and makes it incident along the measurement line ML. The transducer 17 is installed from the outside at a predetermined installation angle θ in a fluid pipe 20 that guides the fluid to be measured.

The ultrasonic pulse oscillated from the transducer 17 is incident on the fluid to be measured flowing in the fluid pipe 20 and is reflected by the ultrasonic reflector that is suspended (mixed). The reflected wave returns to the transducer 17 and is converted into an ultrasonic echo signal corresponding to the magnitude of the reflected wave by the transducer 17. The ultrasonic echo signal that is the reflected wave of the ultrasonic pulse is subsequently sent to the pulsar receiver 14, and the ultrasonic echo signal that is the reflected wave is filtered by a low-pass and high-pass filter built in the pulsar receiver 14 or a band-pass filter. Only the frequency band of the ultrasonic pulse used is extracted, and the adverse effect of noise is suppressed.

The analog ultrasonic echo signal filtered by the pulsar receiver 14 is then sent to the AD converter 15. The AD converter 15 converts an ultrasonic echo signal into a digital signal. The digital ultrasonic echo signal converted by the AD converter 15 is stored in the memory 22 on the board of the AD converter 15 and can be stored in the hard disk of the personal computer 11.

The AD converter 15 has a resolution of, for example, 8 bits and a sampling frequency of up to 500 MHz.

The personal computer 11 which is a signal processing means performs signal processing on an ultrasonic echo signal which is a reflected wave of the ultrasonic pulse, analyzes it, obtains the position and velocity of the ultrasonic reflector or ultrasonic reflector group, and determines the flow velocity of the fluid. The distribution and flow rate are calculated.

Next, processing of the ultrasonic flow velocity distribution measuring method and the flow measuring method according to the present invention will be described.
FIG. 2 shows a flow of the flow rate measuring method according to the present invention.

When a trigger oscillation signal is sent from the trigger oscillation board 12 to the pulsar receiver 14 and the AD converter 15 (S1), an electrical signal for ultrasonic pulse oscillation is transmitted from the pulsar receiver 14 to the transducer 17, and the transducer 17 The pulse oscillation signal is received and converted into an ultrasonic burst signal having a required frequency, for example, 4 MHz, and an ultrasonic pulse is oscillated (S2).

The transducer 17 projects an ultrasonic pulse beam into the fluid pipe 20 and starts receiving a reflected wave from an ultrasonic reflector such as bubbles and particle particles mixed in the measurement target fluid 19 after the ultrasonic pulse is oscillated. Then, the ultrasonic echo signal of the obtained reflected wave is returned to the pulsar receiver 14 (S3). This ultrasonic reflected wave is signal-processed by a bypass and a low-pass filter corresponding to the ultrasonic frequency by the function of the pulser receiver 14 (S4). Thereafter, it is transferred to the AD converter 15 where it is digitally sampled at high speed and digitized (S5).

The sampled digital ultrasonic echo signal is input to the personal computer 11 as signal processing means (S6). By analyzing the digital ultrasonic echo signal inputted by the personal computer 11, the flow velocity distribution of the fluid flowing in the pipe 20 is calculated (S7).

In step S <b> 8, the flow rate is calculated by performing an integration operation along the internal area of the pipe 20 on the synthesized flow velocity distribution data.

As shown in FIG. 3, the flow velocity distribution calculation step S7 by the personal computer 11 includes a correlation calculation processing step (step S71), a phase difference calculation step (step S72), a position / speed calculation step (step S73), and a flow velocity distribution. The calculation step (step S75) and the like.

First, in step S71, an autocorrelation calculation processing step is performed, and for the reference wave extracted from the digital ultrasonic echo signal, the correlation of the search wave searched from the same series is calculated to calculate the correlation value.

  As shown in FIG. 4, the autocorrelation calculation processing step includes a reference wave cutout step (S711), a search wave cutout step (S712), a reference wave wavelet transform step (S713), a search wave wavelet transform step (S714), and the same wavelet. A coefficient comparison step for the function (S715) and a correlation determination-search wave identification step (S716 to S718) are included.

In the reference wave cutout step (S711), a reference wave having a predetermined temporal width is cut out as shown in FIG. The reference wave is selected by selecting a plurality of specific time points from the sampling start time, that is, the distance to be measured, automatically based on the time when the level of the selected digital ultrasonic echo signal exceeds a certain value. Or display a waveform on the screen and accept the designation from the measurer.

  In the search wave cutout step (S712), an arbitrary signal having the same width as the reference wave is cut out.

In the reference wave wavelet transform step (S713), signal conversion is performed according to Equation (4) for the numerical value group a set in advance for the reference wave.

Here, Equation (4) is a coefficient for the wavelet function shown in Equation (5). Further, b is a number determined by the position of the reference wave and the search wave on the time axis, and a is a number corresponding to the frequency of Fourier transform that determines the shape of the wavelet function. In the Fourier transform, the signal is analyzed as a superposition of sine waves. In the wavelet transform, the signal is analyzed as a superposition of this wavelet function. For this reason, the numerical value group of a is set so that ψa is equivalent to the frequency step in the Fourier transform.

In the search wave wavelet transform step (S714), the search wave is converted according to the equation (4) as in S713, and the coefficient of each ψa is obtained.

  In the wavelet comparison step (S715), the coefficients in the reference wave and the search wave are compared for the same wavelet function ψa selected in advance, and the result is stored. The comparison method includes, for example, a method of adding absolute values of coefficient differences and a root of sum of squares of differences (distance in a multidimensional space), but is not limited thereto.

  In the correlation determination-search wave identification step (S716, S718), it is determined that the reference wave and the search wave are echoes from the same reflector when the coefficient separation with respect to the wavelet function is not more than a certain value.

  When the coefficient is equal to or greater than a certain value, the search wave cut-out position is changed (S717), and the correlation is calculated again.

FIG. 5 shows the relationship between the reference wave and the search wave determined to be the same reflected wave as the reference wave.

In the phase difference calculation step of step S72, the phase difference between the phase of the identified search wave and the phase of the reference wave is calculated. In FIG. 5, this corresponds to calculating Δτ, which is the phase difference between the reference wave and the search wave.

In the position / velocity calculating step of step S73, the velocity of the reflector is calculated from the calculated phase difference (Δτ in FIG. 5), and the time of the reflector from the time from the ultrasonic pulse to the ultrasonic echo (τ in FIG. 5) is calculated. Calculate the position.

If it is determined that the position / velocity calculation in step S73 has been completed for all search ranges in the series (S74), a flow velocity distribution calculation step (S75) is performed. In the flow velocity distribution calculation step, the relationship between the position and velocity of the ultrasonic reflector group, that is, the flow velocity distribution is calculated from the reflector group position and velocity. When calculating the flow velocity distribution, the velocities of all ultrasonic reflectors acquired at the same position at the same corresponding time in each series are calculated by averaging or squaring average.

  The present invention can be used in the flow meter and current meter manufacturing industry, the flow meter and current meter sales business and maintenance business, the plant maintenance and maintenance business, and the computer program production and maintenance business related to plant control. There is.

The functional block diagram of the ultrasonic flow velocity distribution meter and flow meter concerning this invention. The flowchart of the ultrasonic flow velocity distribution and flow rate measuring method concerning this invention. The flowchart of the flow-velocity distribution calculation step by a correlation method. The flowchart which performs the correlation determination by wavelet transformation. The figure explaining the relationship between a reference wave and a search wave. The conceptual diagram of a reflection type ultrasonic flowmeter. The figure explaining the reflector which moves the inside of an ultrasonic beam. The figure explaining the position of the reflector in an ultrasonic beam, and an ultrasonic echo signal. The figure explaining the structure of the reflection type ultrasonic flowmeter using a correlation method. The figure which illustrates extraction of a reference wave and a search wave from an ultrasonic echo signal.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Ultrasonic flowmeter 11 Personal computer 12 Trigger oscillation board 13 Connector cable 14 Pulsar receiver 15 AD converter 16 Connector cable 20 Piping 22 Memory 30 Ultrasonic beam 40 Reflector

Claims (4)

A trigger transmission step for outputting a trigger signal;
An ultrasonic pulse oscillation step of oscillating an ultrasonic pulse a plurality of times toward the measurement line of the fluid flowing in the pipe by the trigger signal;
An ultrasonic pulse receiving step for receiving a reflected wave of an ultrasonic pulse by a reflector in the fluid and converting it to an ultrasonic echo signal;
AD conversion step for analog-digital conversion and storing the ultrasonic echo signal;
A correlation calculation step for extracting a reference wave and a search wave from the stored digital ultrasonic echo signal and calculating an autocorrelation;
A phase identifying step that considers the reflected wave from the same reflector when the correlation between the reference wave and the search wave is equal to or greater than a certain value;
A phase difference calculating step of calculating a phase difference between the reference wave and the search wave specified by the phase specifying step;
A velocity calculating step for calculating the velocity of the ultrasonic reflector along the measurement line from the phase difference obtained by the phase difference calculating step;
A position specifying step of specifying a position of a reflector on a measurement line from a time difference between the ultrasonic pulse and an ultrasonic echo with respect to the ultrasonic pulse;
An ultrasonic flow velocity distribution measuring method comprising a flow velocity distribution calculating step of calculating a flow velocity distribution from the calculated velocity and position of the ultrasonic reflector,
The correlation calculation step includes:
A wavelet transform step for wavelet transforming each of the reference wave and the search wave;
Comparing wavelet coefficients for the same wavelet function in the wavelet transformed reference wave and search wave;
A step of determining a correlation between the reference wave and the search wave based on the comparison data,
Ultrasonic velocity distribution measurement method A trigger transmission step for outputting a trigger signal, and an ultrasonic pulse oscillation step for oscillating an ultrasonic pulse a plurality of times toward a measurement line of a fluid flowing in the pipe by the trigger signal;
An ultrasonic pulse receiving step for receiving a reflected wave of an ultrasonic pulse by a reflector in the fluid and converting it to an ultrasonic echo signal;
AD conversion step for analog-digital conversion and storing the ultrasonic echo signal;
A correlation calculation step of extracting a reference wave and a search wave from the stored digital ultrasonic echo signal and calculating an autocorrelation;
A phase identifying step that considers the reflected wave from the same reflector when the correlation between the reference wave and the search wave is equal to or greater than a certain value;
A phase difference calculating step of calculating a phase difference between the reference wave and the search wave specified by the phase specifying step;
The velocity calculation step for calculating the velocity of the ultrasonic reflector along the measurement line from the phase difference obtained by the phase difference calculation step, and the position of the reflector on the measurement line is specified from the time difference between the ultrasonic pulse and the ultrasonic echo corresponding thereto. An ultrasonic flow rate measuring method for calculating a flow rate from a flow rate distribution calculating step and a flow rate distribution calculating step for calculating a flow velocity distribution from the position specifying step, the calculated velocity and position of the ultrasonic reflector,
The correlation calculation step includes:
A wavelet transform step for wavelet transforming each of the reference wave and the search wave;
Comparing wavelet coefficients for the same wavelet function in the wavelet transformed reference wave and search wave;
A step of determining a correlation between the reference wave and the search wave based on the comparison data,
Ultrasonic flow measurement method A trigger transmission step for outputting a trigger signal;
An ultrasonic pulse oscillation step of oscillating an ultrasonic pulse a plurality of times toward the measurement line of the fluid flowing in the pipe by the trigger signal;
An ultrasonic pulse receiving step for receiving a reflected wave of an ultrasonic pulse by a reflector in the fluid and converting it to an ultrasonic echo signal;
AD conversion step for analog-digital conversion and storing the ultrasonic echo signal;
A correlation calculation step for extracting a reference wave and a search wave from the stored digital ultrasonic echo signal and calculating an autocorrelation;
A phase identifying step that considers the reflected wave from the same reflector when the correlation between the reference wave and the search wave is equal to or greater than a certain value;
A phase difference calculating step of calculating a phase difference between the reference wave and the search wave specified by the phase specifying step;
A velocity calculating step for calculating the velocity of the ultrasonic reflector along the measurement line from the phase difference obtained by the phase difference calculating step;
A position specifying step of specifying a position of a reflector on a measurement line from a time difference between the ultrasonic pulse and an ultrasonic echo with respect to the ultrasonic pulse;
An ultrasonic flow velocity distribution measurement program comprising a flow velocity distribution calculation step for calculating a flow velocity distribution from the calculated velocity and position of the ultrasonic reflector,
The correlation calculation step includes:
A wavelet transform step for wavelet transforming each of the reference wave and the search wave;
Comparing wavelet coefficients for the same wavelet function in the wavelet transformed reference wave and search wave;
A step of determining a correlation between the reference wave and the search wave based on the comparison data,
Ultrasonic velocity distribution measurement program A trigger transmission step for outputting a trigger signal, and an ultrasonic pulse oscillation step for oscillating an ultrasonic pulse a plurality of times toward a measurement line of a fluid flowing in the pipe by the trigger signal;
An ultrasonic pulse receiving step for receiving a reflected wave of an ultrasonic pulse by a reflector in the fluid and converting it to an ultrasonic echo signal;
AD conversion step for analog-digital conversion and storing the ultrasonic echo signal;
A correlation calculation step of extracting a reference wave and a search wave from the stored digital ultrasonic echo signal and calculating an autocorrelation;
A phase identifying step that considers the reflected wave from the same reflector when the correlation between the reference wave and the search wave is equal to or greater than a certain value;
A phase difference calculating step of calculating a phase difference between the reference wave and the search wave specified by the phase specifying step;
The velocity calculation step for calculating the velocity of the ultrasonic reflector along the measurement line from the phase difference obtained by the phase difference calculation step, and the position of the reflector on the measurement line is specified from the time difference between the ultrasonic pulse and the ultrasonic echo corresponding thereto. An ultrasonic flow measurement program for calculating a flow rate from a flow rate distribution calculating step and a flow velocity distribution calculating step for calculating a flow velocity distribution from the position specifying step, the calculated velocity and position of the ultrasonic reflector,
The correlation calculation step includes:
A wavelet transform step for wavelet transforming each of the reference wave and the search wave;
Comparing wavelet coefficients for the same wavelet function in the wavelet transformed reference wave and search wave;
A step of determining a correlation between the reference wave and the search wave based on the comparison data,
Ultrasonic flow measurement program