阅读说明：本技术 基于包络阈值-峰值法的超声波流量计时间差稳定测量方法 (Ultrasonic flowmeter time difference stable measurement method based on envelope threshold value-peak value method ) 是由 王士兴 胡香儒 杨朋 曹文文 于 2021-08-04 设计创作，主要内容包括：基于包络阈值-峰值法的超声波流量计时间差稳定测量方法,通过计算上行、下行回波信号包络阈值对应时间之差绝对值ΔThr和上行、下行回波信号峰值之差绝对值ΔPeak,然后通过条件|ΔPeak-ΔThr|与触发移波点数N-(HW)的大小关系判断本次计算时间差是否可靠,如果存在跳波现象,可以通过上行、下行回波峰值前第4个波的幅值大小判断条件进行移波,消除跳波问题,本发明能够对时间差测量的可靠性进行判断,在时间差测量不可靠时,通过移波处理,可以得到真实的时间差测量值；本发明能够解决在复杂不稳定的工况下,如气流不稳、不同压力、现场震动等场合,对超声波回波信号特征有一定影响状况下出现跳波的问题,从而保证流量计在计量应用场合的稳定性和可靠性。(An envelope threshold-Peak method based ultrasonic flowmeter time difference stable measurement method comprises the steps of calculating the absolute value delta Thr of the difference between corresponding time of an envelope threshold of uplink echo signals and corresponding time of downlink echo signals and the absolute value delta Peak of the difference between Peak values of the uplink echo signals and the downlink echo signals, and then calculating the absolute value delta Peak-delta Thr | of conditions and the number N of triggered wave-shifting points HW The method can judge the reliability of time difference measurement, and when the time difference measurement is unreliable, a real time difference measurement value can be obtained through wave shifting processing; the invention can solve the problem of wave jump under the conditions of complicated and unstable working conditions, such as unstable airflow, different pressures, field vibration and the like, which have certain influence on the characteristics of ultrasonic echo signals,thereby ensuring the stability and reliability of the flowmeter in the metering application occasions.)

1. The method for stably measuring the time difference of the ultrasonic flowmeter based on the envelope threshold value-peak value method is characterized by comprising the following steps of:

collecting and amplifying uplink and downlink echo signals;

step (2), calculating the absolute value delta Peak of the difference between the corresponding time of the uplink Peak value and the downlink Peak value, calculating the absolute value delta Thr of the difference between the corresponding time of the uplink envelope threshold value and the downlink envelope threshold value, and calculating

Step (3), judging | Delta Peak-Delta Thr | and triggering wave-shifting point number N_HWThe time difference DTOF calculation is confirmed whether reliable or not, and finally the reliable time difference DTOF is determined.

2. An ultrasonic flow meter time difference stability measurement method based on an envelope threshold-peak method according to claim 1,

the step (1) is specifically as follows: soft-playing the collected up and down echo signals to a target amplitude V based on a peak value_TCarrying out magnification at the same ratio.

3. An ultrasonic flow meter time difference stability measurement method based on an envelope threshold-peak method according to claim 1,

the step (2) is specifically as follows:

acquiring envelope signals of the amplified uplink echo signals and the amplified downlink echo signals, calculating the corresponding time of the amplified uplink envelope threshold value and the amplified downlink envelope threshold value on the envelope signals, and recording the uplink as TUp_ThrAnd down is denoted as TDown_Thr；

Calculating the absolute value of the time difference between the amplified uplink envelope threshold and the amplified downlink envelope threshold, and recording the absolute value as delta Thr, delta Thr ═ TUp_Thr-TDown_Thr|；

Calculating the time corresponding to the amplified uplink and downlink echo peak values, and recording the uplink as TUp_PeakAnd down is denoted as TDown_Peak；

Calculating the absolute value of the time difference between the amplified up and down Peak values, and recording as delta Peak, where delta Peak is | TUp_Peak-TDown_Peak|。

4. An ultrasonic flow meter time difference stability measurement method based on an envelope threshold-peak method according to claim 3,

the method for acquiring the envelope signal comprises the following steps: connecting the maximum value points of each wave of the echo signal to obtain an envelope signal of the echo signal, or acquiring signal envelope by a Hilbert transform method.

5. An ultrasonic flow meter time difference stability measurement method based on an envelope threshold-peak method according to claim 1,

the step (3) is specifically as follows:

judging | Delta Peak-Delta Thr | and triggering wave-shifting point number N_HWIf the size relationship of | Delta Peak-Delta Thr | is less than or equal to N_HWThe time difference DTOF calculation is reliable, if | Δ Peak- Δ Thr $ ->N_HWIf the time difference DTOF is unreliable, the wave jump occurs;

if the time difference DTOF is reliably calculated, the difference between the rear zero-crossing points of the threshold trigger waves of the uplink echo and the downlink echo is recorded as the time difference DTOF;

if the time difference DTOF calculation is unreliable and the jumping wave occurs, calculating the amplitude of the 4 th wave before the uplink peak value and the downlink peak value, wherein the amplitude of the 4 th wave before the uplink peak value is Vup_BW4The amplitude of the 4 th wave before the down peak is VDown_BW4If Vup is_BW4≥VDown_BW4The uplink echo is advanced by one cycle, the uplink echo threshold triggers an advance by 1 wave, if Vup_BW4<VDown_BW4The downlink echo moves forward for a period, the downlink echo threshold triggers forward 1 wave, the difference between the zero crossing points after the uplink and downlink echo threshold triggers is the time difference DTOF, and the value is the reliable time difference DTOF for eliminating the influence of wave hopping.

6. An ultrasonic flow meter time difference stability measurement method based on an envelope threshold-peak method according to claim 5,

number of trigger shift points N_HWThe empirical value of (c) is 0.75 echo cycle points.

Technical Field

The invention belongs to a flow measurement method in the technical field of measurement, and particularly relates to a method for stably measuring time difference of an ultrasonic flowmeter based on an envelope threshold-peak method.

Background

Compared with other meters, the ultrasonic flowmeter has obvious advantages in the aspects of accuracy, repeatability, range ratio, reliability, stability, pressure loss, daily maintenance and the like, is widely applied to trade metering application occasions at present, and uses the ultrasonic flowmeter as a main trade transfer metering instrument in occasions such as west-gas-east pipelines and the like.

Most products of ultrasonic wave measurement are only suitable for the ordinary pressure environment at present, can't adapt to the high pressure application occasion, and pipeline pressure, gas flow state change can arouse the change of ultrasonic wave echo signal wave form characteristic in high pressure environment, lead to the time difference measurement cycle beat even in disorder for flow measurement is unstable and unreliable, so, seeks a can be reliable and stable measuring method and has vital meaning to the development of ultrasonic wave flowmeter.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention aims to provide a method for stably measuring the time difference of an ultrasonic flowmeter based on an envelope threshold-peak method, which can judge the reliability of time difference measurement and obtain a real time difference measured value through wave shifting processing when the time difference measurement is unreliable; the invention can solve the problem of wave jumping under the conditions of certain influence on the characteristics of ultrasonic echo signals under the complicated and unstable working conditions, such as unstable airflow, different pressures, field vibration and the like, thereby ensuring the stability and reliability of the flowmeter in the metering application occasions.

In order to achieve the purpose, the technical scheme of the invention is as follows:

the method for stably measuring the time difference of the ultrasonic flowmeter based on the envelope threshold value-peak value method comprises the following steps:

(1) collecting and amplifying uplink and downlink echo signals;

soft-playing the collected up and down echo signals to a target amplitude V based on a peak value_TCarrying out same-ratio amplification;

(2) calculating the absolute value delta Peak of the difference between the corresponding time of the uplink Peak value and the downlink Peak value, calculating the absolute value delta Thr of the difference between the corresponding time of the uplink envelope threshold value and the downlink envelope threshold value, and calculating | delta Peak-delta Thr |;

the method specifically comprises the following steps:

acquiring envelope signals of the amplified uplink echo signals and the amplified downlink echo signals, calculating the corresponding time of the amplified uplink envelope threshold value and the amplified downlink envelope threshold value on the envelope signals, and recording the uplink as TUp_ThrAnd down is denoted as TDown_Thr；

Calculating the absolute value of the time difference between the amplified uplink envelope threshold and the amplified downlink envelope threshold, and recording the absolute value as delta Thr, delta Thr ═ TUp_Thr-TDown_Thr|；

Calculating the time corresponding to the amplified uplink and downlink echo peak values, and recording the uplink as TUp_PeakAnd down is denoted as TDown_Peak；

Calculating the absolute value of the time difference between the amplified up and down Peak values, and recording as delta Peak, where delta Peak is | TUp_Peak-TDown_Peak|；

(3) Judging | Delta Peak-Delta Thr and triggering wave-shifting point number N_HWDetermining whether the time difference DTOF calculation is reliable or not, and finally determining the reliable time difference DTOF;

the method specifically comprises the following steps: judging | Delta Peak-Delta Thr and the number N of trigger wave-shifting points_HWIf the size relationship of | Delta Peak-Delta Thr | is less than or equal to N_HWIf so, the time difference DTOF is reliably calculated; if | Δ Peak- Δ Thr | is > N_HWIf the time difference DTOF is unreliable, the wave jump occurs;

if the time difference DTOF is reliably calculated, the difference between the rear zero-crossing points of the threshold trigger waves of the uplink echo and the downlink echo is recorded as the time difference DTOF;

if the time difference DTOF calculation is unreliable and the wave jump occurs, the uplink is calculated,The 4 th wave amplitude before the downlink peak value and the 4 th wave amplitude before the uplink peak value are Vup_BW4The amplitude of the 4 th wave before the down peak is VDown_BW4If Vup is_BW4≥VDown_BW4The uplink echo is advanced by one cycle, the uplink echo threshold triggers an advance by 1 wave, if Vup_BW4＜VDown_BW4The downlink echo is shifted by one period, the downlink echo threshold triggers the forward shift by 1 wave, the difference between the zero crossing points after the uplink echo threshold trigger and the downlink echo threshold trigger is the time difference DTOF, and the value is the reliable time difference DTOF for eliminating the influence of wave hopping.

Compared with the prior art, the invention has the following beneficial effects:

the invention provides an ultrasonic flowmeter time difference stable measurement method based on an envelope threshold value-peak value method, which can solve the problem that the flow meter data is inaccurate and unstable due to time difference measurement errors because the calculated time difference has fixed deviation with the echo signal cycle time as a unit under the condition that echo characteristics are changed in a complex working condition occasion; the method can detect the wave hopping phenomenon through the preset wave hopping judgment condition and solve the problem of the wave hopping through the wave shifting method, so that the measured time difference is accurate and stable, the measured data of the ultrasonic flowmeter in the metering application occasion is accurate and reliable, and the tradition dispute caused by overlarge deviation of the measured data is avoided.

Drawings

FIG. 1 is a flow chart of the present invention.

Detailed Description

The present invention is described in further detail below with reference to the attached drawings.

Referring to fig. 1, the method for ultrasonic flowmeter time difference stability measurement based on the envelope threshold-peak method comprises the following steps:

(1) collecting and amplifying uplink and downlink echo signals

Soft-playing the collected up and down echo signals to a target amplitude V based on a peak value_TPerforming a same ratio amplification of V_TIs typically 5V, but may be other than the typical value.

(2) Calculating the absolute value delta Peak of the difference between the corresponding time of the uplink Peak value and the downlink Peak value, calculating the absolute value delta Thr of the difference between the corresponding time of the uplink envelope threshold value and the downlink envelope threshold value, and calculating | delta Peak-delta Thr |;

acquiring envelope signals of the amplified uplink echo signals and the amplified downlink echo signals, wherein the method for acquiring the envelope signals is to connect maximum value points of all waves of the echo signals to obtain the envelope signals of the echo signals; the method of retrieving the wave envelope signal of the present invention is not limited to the method, and other methods of retrieving the wave envelope signal are also applicable to the present method, such as: a method of using the hilbert transform method to obtain a signal envelope, and the like.

Calculating the corresponding time of the amplified upstream and downstream envelope thresholds Thr on the envelope signal, and recording the upstream as TUp_ThrAnd down is denoted as TDown_ThrWherein, the typical value of the envelope threshold Thr is 1.2v, and it can be other amplitudes besides the typical value.

Calculating the absolute value of the time difference between the amplified uplink envelope threshold and the amplified downlink envelope threshold, and recording the absolute value as delta Thr, delta Thr ═ TUp_Thr-TDown_Thr|。

Calculating the time corresponding to the amplified uplink and downlink echo peak values, and recording the uplink as TUp_PeakAnd down is denoted as TDown_Peak。

Calculating the absolute value of the time difference between the amplified up and down Peak values, and recording as delta Peak, where delta Peak is | TUp_Peak-TDown_Peak|。

(3) Judging the | Δ Peak- Δ Thr | and the number N of trigger wave-shifting points_HWDetermining whether the time difference DTOF calculation is reliable or not, and finally determining the reliable time difference DTOF;

judging | Delta Peak-Delta Thr | and triggering wave-shifting point number N_HWIf the size relationship of | Delta Peak-Delta Thr | is less than or equal to N_HWThe time difference DTOF calculation is reliable, if | Δ Peak- Δ Thr $ ->N_HWIf the time difference DTOF is unreliable, the wave jump occurs, wherein the number N of the triggered wave shift points_HWThe empirical value of (c) is 0.75 echo cycle points.

If the time difference DTOF is calculated reliably, the difference between the rear zero-crossing points of the threshold trigger waves of the uplink echo and the downlink echo is recorded as the time difference DTOF.

If the jumping wave occurs, calculating the amplitude of the 4 th wave before the uplink peak value and the downlink peak value, wherein the amplitude of the 4 th wave before the uplink peak value is Vup_BW4The amplitude of the 4 th wave before the down peak is VDown_BW4If Vup is_BW4≥VDown_BW4The uplink echo is advanced by one cycle, the uplink echo threshold triggers an advance by 1 wave, if Vup_BW4＜VDown_BW4The downlink echo is advanced by one period, the downlink echo threshold value is triggered to advance by 1 wave, the difference between the zero crossing points after the uplink echo threshold value trigger and the downlink echo threshold value trigger is the time difference DTOF, and the value is the reliable time difference DTOF for eliminating the influence of wave hopping.

In conclusion, the method and the device can solve the problem that the calculated time difference has wave jumping under the condition of echo characteristic change caused in a complex working condition occasion, improve the stability and the reliability of time difference measurement, and ensure that the measurement data of the ultrasonic flowmeter in a metering application occasion are stable and reliable.