CN101813528B - Method for precisely measuring temperature by using ultrasonic technology and measuring instrument - Google Patents

Abstract

The invention relates to a method for precisely measuring temperature by using ultrasonic technology and a measuring instrument. The measuring instrument mainly comprises an ultrasonic temperature sensor, an ultrasonic transducer drive circuit, an ultrasonic echo signal processing circuit and an interface circuit. The ultrasonic temperature sensor comprises an ultrasonic transducer and a closed tube body filled with a medium capable of propagating ultrasonic wave. The ultrasonic transducer drive circuit mainly comprises a D/A converter and a power amplifying circuit. The ultrasonic echo signal processing circuit mainly comprises a filter circuit, an amplifying circuit, an A/D, an FPGA and a CPU. The ultrasonic transducer drive circuit drives the transducer to emit the ultrasonic wave, and the ultrasonic echo signal processing circuit precisely measures the propagation time of the ultrasonic wave in the tube body. The propagation speed of the ultrasonic wave in the medium is changed along with the change of the temperature, and the measurement of the temperature can be realized by measuring the propagation time of the ultrasonic wave in the tube body at different temperatures. The measuring instrument can realize high-precision temperature measurement, the precision of temperature measurement depends on the measurement precision of the propagation time of the ultrasonic wave, and the measurement range depends on the length of the tube body.

Description

A kind of method and measuring instrument that utilizes the ultrasonic technology precisely measuring temperature

Technical field

The invention belongs to sophisticated sensor and detection technique field, be specifically related to a kind of temperature measuring set with the ultrasonic technology precisely measuring temperature.

Background technology

Hyperacoustic notable feature is that frequency is high, thereby wavelength is short, and the diffraction phenomenon is little, and good directionality can direction propagation, runs into impurity or interphase during propagation and just has significant reflection.Along with development of electronic technology, the increasing precision measurement that is applied to temperature etc. of ultrasonic technology.

When ultrasound wave was propagated in medium, velocity of propagation changed with the variation of state parameters such as temperature, pressure.The hundreds of approximately rice of velocity of propagation per second increased with the temperature rising when ultrasound wave was propagated in gas, and air middle pitch speed is 331.4 meter per seconds in the time of 0 ℃, is 340 meter per seconds in the time of 15 ℃, 1 ℃ of the every rising of temperature, and velocity of sound increases by 0.6 meter per second approximately.Record transmission range ultrasound wave travel-time under different temperatures when constant, just can record temperature.For example, hyperacoustic speed is 344 meter per seconds in the time of 20 ℃, and hyperacoustic speed is 344.6 meter per seconds in the time of 21 ℃, if hyperacoustic transmission range is 0.3 meter, then hyperacoustic transmission time is 8.7209 * 10 in the time of 20 ℃ ^-4Second, hyperacoustic transmission time is 8.7057 * 10 in the time of 21 ℃ ^-4Second, hyperacoustic transmission time difference is 1.52 * 10 in the time of 21 ℃ and 20 ℃ the time ^-6Second.Guarantee to measure and reach 0.001 ℃ Measurement Resolution, require the resolution of ultrasonic transmission time measurement to reach and could realize 1～2 nanosecond.If with conventional hyperacoustic transmission time of timer counter circuit measuring, then the frequency of clock circuit will reach 1G at least, this obviously is difficult to realize for instrument development.

Summary of the invention

The present invention is directed to the problems referred to above; Precision temperature measuring method and temperature measuring set that a kind of Measurement Resolution can reach 0.001 ℃ are disclosed; Ultrasonic temperature sensor, FPGA circuit and software segmentation interpolation algorithm have been designed; Can under the prerequisite that guarantees the measurement real-time, realize the measurement of nanosecond ultrasonic transmission time, thereby realize the high-precision temperature measurement.

The technical scheme that the present invention adopts is:

The present invention is used to realize that Measurement Resolution is superior to 0.001 ℃ precision temperature measurement, and said thermometry adopts ultrasonic temperature sensor, hardware circuit and related algorithm two parts.Ultrasonic temperature sensor comprises two the ultrasonic transducer E1 and the E2 that are full of the airtight withstand voltage body of ultrasonic medium and are installed in the body two ends respectively; Hardware circuit mainly comprises ultrasonic transducer drive circuit, ultrasonic echo signal filter circuit, amplifying circuit and signal processing circuit.Signal processing circuit mainly contains analog to digital converter (A/D), FPGA (FPGA) and CPU (CPU).

Said transducer E1 is a piezoelectric transducer, can be the electrical signal conversion with certain energy mechanical vibration, and when the frequency of signal was in the frequency of ultrasonic scope, transducer E1 was electrical signal conversion a ultrasonic signal.Transducer E2 also is a piezoelectric transducer, converts mechanical vibration into electric signal, and when ultrasonic signal affacted on the ultrasonic transducer E2, it converted ultrasonic signal into electric signal, and this signal can be referred to as the ultrasonic echo signal.

Said ultrasonic transducer drive circuit comprises digital to analog converter (D/A) and power amplification circuit.The digital sine conversion of signals that D/A converter is used for sending FPGA is an analog sinus signals, and power amplification circuit is used to amplify the power of this sinusoidal signal, makes it enough energy drives ultrasonic transducer E1.It is digital signal that said A/D converter is mainly used in a ultrasonic echo analog signal conversion, and input FPGA.

Said FPGA circuit major function has two: first function is under the control of CPU, to produce the digital sine signal, and this signal converts simulating signal to through D/A converter, and amplifies rear drive transducer E1 through power amplification circuit.Second function is to accomplish the ultrasonic echo signals sampling, and has data in the memory block that is configured in FPGA inside.

The sinusoidal ultrasonic signal of periodicity of ultrasonic transducer E1 emission some; After this signal is propagated in medium and is arrived transducer E2; Excitation transducer E2 produces the ultrasonic echo signal, and the continuous pump of the ultrasonic signal that the amplitude of echoed signal receives along with transducer and increasing gradually is when pumping signal stops; The mechanical vibration of transducer still can continue under action of inertia and decay gradually; The amplitude of echoed signal also reduces gradually, so the ultrasonic echo signal is a luffing cyclical signal, and its cycle is corresponding to the cycle of ultrasonic signal.That cycle of echoed signal amplitude maximum is corresponding to the cycle of last sent that ultrasonic signal of transducer E1.

Hyperacoustic travel-time is exactly the corresponding time interval between that a bit and on the echoed signal that receives of transducer E2 arbitrarily on the ultrasonic signal that sends of transducer E1.The key of ultrasonic transmission time measurement is to confirm the starting point and the terminal point in travel-time.The starting point in travel-time can be the specific pairing moment on the ultrasonic signal that sends of transducer E1, the terminal point of time be on the echoed signal with corresponding that pairing moment of ultrasonic signal unique point.

Echoed signal is a Variable Amplitude cyclical signal, and the most characteristic ripple is that maximum ripple of amplitude in its waveform, can be referred to as characteristic wave, and characteristic wave is corresponding to last ripple of ultrasonic signal.In characteristic wave, the most characteristic point is zero crossing and peak point, can select the unique point of zero crossing as echoed signal.The unique point moment corresponding is exactly the terminal point in travel-time, and is corresponding with it, and the pairing moment of zero crossing of last that ripple can be confirmed as the starting point in travel-time in the ultrasonic signal waveform.

Because ultrasonic signal is that FPGA produces under the control of CPU, the starting point in travel-time, just the zero crossing moment corresponding of last that ripple of ultrasonic signal is easy to confirm accurately that by CPU its precision depends on the running frequency of FPGA.

The terminal point in travel-time, just the pairing moment of zero crossing is confirmed through the segmentation interpolation algorithm in the echoed signal characteristic wave.The segmentation interpolation algorithm is according to the waveform in that cycle of peak amplitude maximum in the at first definite echoed signal of the A/D sampled signal of the ultrasonic echo of storing among the FPGA; Confirm former and later two sampled points of zero crossing (ratio zero is big, and a ratio zero is little) pairing moment then; Be benchmark with former and later two sampled points of zero crossing at last; With fit method sampled point is segmented interpolation; Confirm the pairing moment of echoed signal zero crossing, i.e. in the pairing moment of ultrasonic propagation time terminal point, its precision depends primarily on the resolution of A/D sampling.

The high-precision ultrasonic thermometry that the present invention proposes is following: ultrasonic transducer E1 and ultrasonic transducer E2 are installed in the body two ends relatively; Central processing unit CPU control on-site programmable gate array FPGA sine wave output drive signal; Let signal input to said ultrasonic transducer E1 through D/A change-over circuit and power amplification circuit successively, this ultrasonic transducer E1 converts said this input signal to mechanical vibration and produces ultrasonic signal.

Said ultrasonic transducer E2 receives the ultrasonic signal that said ultrasonic transducer E1 sends; And output ultrasonic wave echoed signal; By filtering circuit the ultrasonic echo signal that ultrasonic transducer E2 sends is carried out filtering; After being amplified by amplifying circuit, by the A/D change-over circuit echoed signal is sampled, sampled data is stored in earlier in the memory block that is configured in the FPGA again.

After sampling is accomplished; Central processing unit CPU is at first launched hyperacoustic data according to FPGA and is confirmed the pairing moment of ultrasonic propagation time starting point; Read the A/D sampled data of ultrasonic echo signal then in the FPGA; Employing accurately calculates the pairing moment of ultrasonic propagation time terminal point through the segmentation interpolation algorithm, and then accurately confirms the transmission time of ultrasound wave between two transducer E1, E2.Last CPU is according to ultrasound wave different transmission times between two transducer E1, the E2 in the ultrasonic temperature sensor body, be combined under the different temperatures with different medium in hyperacoustic transmission speed, accurate Calculation obtains the temperature of temperature sensor.

Thus, the high-precision ultrasonic thermometer of the present invention's proposition comprises ultrasonic transducer E1, ultrasonic transducer E2, D/A change-over circuit, power amplification circuit, signal amplification circuit, filtering circuit, A/D change-over circuit, on-site programmable gate array FPGA and central processing unit CPU;

Said ultrasonic transducer E1 and ultrasonic transducer E2 are installed in the body two ends relatively, exist between two transducers can propagate ultrasound waves medium.

Said central processing unit CPU connects on-site programmable gate array FPGA; Control on-site programmable gate array FPGA sine wave output drive signal; One tunnel output of on-site programmable gate array FPGA connects the D/A change-over circuit, by the D/A change-over circuit said sine wave drive signal is changed, and the D/A change-over circuit connects power amplification circuit again; Signal is amplified; Power amplification circuit is connected with ultrasonic transducer E1, and signal is inputed to said ultrasonic transducer E1, and this ultrasonic transducer E1 converts said this input signal to mechanical vibration and produces ultrasonic signal;

Said ultrasonic transducer E2 receives the ultrasonic signal that said ultrasonic transducer E1 sends; Convert mechanical vibration into electric signal; The output ultrasonic wave echoed signal; And through with its amplifying circuit that is connected successively, filtering circuit and A/D change-over circuit, make said ultrasonic echo signal after amplification, filtering and A/D conversion, input to on-site programmable gate array FPGA successively;

Said on-site programmable gate array FPGA sample simultaneously sine wave drive signal and the ultrasonic echo signal of input of output, and sampled data left in the internal memory;

Said central processing unit CPU reads sampled data from the on-site programmable gate array FPGA internal memory, accurately calculate the pairing moment of ultrasonic propagation time terminal point through the segmentation interpolation algorithm; Then, confirm the pairing moment of ultrasonic propagation time starting point according to the sine wave drive signal of output.Thereby accurately confirm the transmission time of ultrasound wave between two transducer E1, E2.Last CPU is according to ultrasound wave different transmission times between two transducer E1, the E2 in the ultrasonic temperature sensor body, be combined under the different temperatures with different medium in hyperacoustic transmission speed, accurate Calculation obtains the temperature of temperature sensor.

The present invention can realize the measurement of the ultrasonic transmission time of nanosecond precision owing to adopted based on the hardware circuit of FPGA and special software algorithm of subdivision, thereby realizes that resolution is superior to 0.001 ℃ high-precision temperature measurement, and guarantees good real-time.The present invention can be widely used in fields such as precision temperature measurement and control.

Description of drawings

Fig. 1 is a kind of high-precision temperature meter structural drawing;

Fig. 2 is the drive signal synoptic diagram that is added on the transducer E1;

Fig. 3 is the ultrasonic echo signal schematic representation that receives on the transducer E2;

Fig. 4 is a kind of working principle of hardware synoptic diagram of precisely measuring ultrasonic wave transmission time method;

Fig. 5 a-5b is a synoptic diagram of confirming the corresponding moment of ultrasonic propagation time terminal point institute.

Embodiment

Below in conjunction with Figure of description technical scheme of the present invention is done further explain.

Referring to Fig. 1; This thermometer is mainly by body 10, ultrasonic transducer E111, transducer E212, central processing unit CPU 19, FPGA FPGE118; A/D change-over circuit 17; Filtering circuit 16, amplifying circuit 15, power amplification circuit 14, D/A change-over circuit 13, display circuit 20, keyboard circuit 21 and D/A change-over circuit 22 constitute.Ultrasonic transducer E111, the ultrasonic transducer E212 at two ends constitute temperature sensor in body 10 and the pipe, and being full of in the body can propagate ultrasound waves and the bigger medium of ultrasonic velocity temperature influence, such as air, and water etc.Display circuit 20 is used to the temperature value that shows that CPU calculates; Keyboard circuit 21 is used for to the parameter of input temp meter and operating personnel's authority; D/A change-over circuit 22 converts temperature value to analog current signal from digital signal, 4～20 milliamperes of normalized current signals commonly used in the output Engineering Control.Ultrasonic transducer is a piezoelectric transducer.

Referring to Fig. 2; Be the drive signal on the ultrasonic transducer E1, it is that the digital sine signal that in FPGA, produces converts analog sinus signals to through the D/A change-over circuit, and then forms through the power amplification circuit amplification; The voltage of the V representation signal among the figure, t represents the time.The frequency of this signal is 1MHz, the about 10V of voltage, and the about 1.5A of electric current has about 15 watts electric energy, is enough to drive ultrasonic transducer E1 and converts electrical energy into mechanical energy, sends ultrasonic signal.

Referring to Fig. 3, be the ultrasonic echo signal of on transducer E2, exporting, the voltage of the V representation signal among the figure, t represents the time.When the ultrasonic signal that transducer E1 sends was gone up through propagating into transducer E2 after certain travel-time, transducer E2 converted the mechanical energy of ultrasonic signal into electric energy, the output ultrasonic wave echoed signal.The electric signal of transducer E2 output is not before ultrasound wave propagates on the transducer E2; Amplitude is zero; After transducer E2 received ultrasonic signal, the electric signal amplitude of output increased gradually, reduced to decay to zero then gradually; Be a luffing periodic signal, that ripple of amplitude maximum is corresponding to last ripple of ultrasonic signal.The frequency of ultrasonic echo signal depends on the frequency of ultrasonic signal, also is 1MHz.

Referring to Fig. 4, after the synchronizing circuit 432 of CPU19 in FPGA18 sent the beginning sample command, FPGA18 started to the driving of ultrasonic transducer E111 with to ultrasonic transducer E212 output signals sampling simultaneously.

The digital sine signal generator 431 transmission frequencies that are implemented in the FPGA are the sinusoidal signal in 8 cycles of 1MHz; This signal converts simulating signal into through D/A change-over circuit 13; After power amplification circuit 14 amplifies, be carried on the transducer E111 again, send ultrasonic signal.After the electric signal of transducer E212 output amplifies through operational amplification circuit 15, through being connected to A/D change-over circuit 17 after filtering circuit 16 filtering.The inner sample circuit 433 control A/D change-over circuits 443 of FPGA are digital signal with analog signal conversion, and deposit sampled value one by one in the RAM memory block 434 that is implemented in the FPGA.After sampling was accomplished, FPGA430 sent sampling done state information to CPU 19, and CPU19 finishes once sampling after receiving sampling done state information.

After sampling finished, CPU19 at first accurately confirmed the pairing moment T of starting point in the ultrasonic signal according to the data of the digital sine signal generator 431 in the FPGA _QD

CPU19 sends the read data order then, reads the data that are temporary in the RAM memory block 434, the pairing moment of accurate Calculation ultrasonic propagation time terminal point.

The pairing moment of ultrasonic transmission end time is through analyzing and calculate and realize with the segmentation interpolation algorithm all sampled datas of echoed signal.Referring to Fig. 5 a, analyze the ultrasonic echo signal of ultrasonic transducer E2 output and can know, be the repeatability that guarantees measurement, should in the waveform of peak amplitude maximum, extract the terminal point of ultrasonic transmission time.In the complete cycle of this waveform, the most tangible two unique points are peak point and zero crossing, and the time reference of confirming as zero crossing echoed signal obtains high precision more easily.

Referring to Fig. 5 a, the computing method in the pairing moment of ultrasonic transmission end time of the present invention are:

At first the A/D sampled point is compared in pointwise, finds out the maximal value of sampled point and just can confirm the waveform that amplitude is maximum easily, can be referred to as the eigenwert waveform to this waveform;

Secondly, participate in Fig. 5 b, confirm the pairing zero crossing P of ultrasonic transmission end time ₀Sampled point P+1 of sampled point P in front and back, obviously the sampled value of sampled point P is greater than zero in characteristic wave, and the sampled value of sampled point P+1 is less than zero;

At last, as benchmark, can accurately calculate zero crossing P with sampled point P and 2 moment corresponding of P+1 with the segmentation interpolation algorithm ₀In the pairing moment, concrete computing method are following:

If the SF of A/D is F _A/D, the time between adjacent two sampled points is to be T in the sampling period _A/DIs N from first sampled point to the hits the sampled point P, and the sampled value that sampled point P is corresponding is V1, and the pairing moment of sampled point P is T1; The sampled value that sampled point P+1 is corresponding is V2; The pairing moment of sampled point P is T1, sampled point P and zero crossing P ₀Between time be T2, zero crossing P ₀Moment corresponding is T _ZD, hyperacoustic transmission time is T, then:

$T_{A/D}=\frac{1}{F_{A/D}}$

$\mathrm{<figure-callout\; id="1"\; label="T"\; filenames="HSA00000109759000023.png"\; state="\{\{state\}\}">T</figure-callout>}1=N\&times;\frac{1}{F_{A/D}}$

In the less zone of near zero-crossing point, sinusoidal wave waveform approaches straight line, can confirm T2 according to the method for linear interpolation:

$T2=\frac{1}{V2-\mathrm{<figure-callout\; id="1"\; label="V"\; filenames="HSA00000109759000023.png"\; state="\{\{state\}\}">V</figure-callout>}1}\&times;\mathrm{<figure-callout\; id="1"\; label="V"\; filenames="HSA00000109759000023.png"\; state="\{\{state\}\}">V</figure-callout>}1\&times;T_{A/D}$

Then the pairing moment of zero crossing, promptly the pairing moment of ultrasonic transmission end time is:

$T_{\mathrm{ZD}}=\mathrm{<figure-callout\; id="1"\; label="T"\; filenames="HSA00000109759000023.png"\; state="\{\{state\}\}">T</figure-callout>}1+T2=N\&times;\frac{1}{T_{A/D}}+\frac{1}{V2-\mathrm{<figure-callout\; id="1"\; label="V"\; filenames="HSA00000109759000023.png"\; state="\{\{state\}\}">V</figure-callout>}1}\&times;T_{/\mathrm{AD}}\&times;\mathrm{<figure-callout\; id="1"\; label="V"\; filenames="HSA00000109759000023.png"\; state="\{\{state\}\}">V</figure-callout>}1$

Can know from following formula, the ultrasonic transmission end time corresponding resolution constantly be:

$R=\frac{1}{V2-\mathrm{<figure-callout\; id="1"\; label="V"\; filenames="HSA00000109759000023.png"\; state="\{\{state\}\}">V</figure-callout>}1}\&times;T_{/\mathrm{AD}}$

Participate in Fig. 5 b, the frequency of supposing the ultrasonic echo signal is 1M, and then the cycle is 1us; The resolution of A/D is 12; Can the amplitude of signal be divided into 4096 parts so; If the SF of A/D is 32MHz, then arrive in the negative peaked half period in the positive maximal value of sine wave, can adopt 16 points at most; If regard sinusoidal wave positive maximal value as straight line to the waveform in the negative peaked half period, then obviously can know:

$V2-\mathrm{<figure-callout\; id="1"\; label="V"\; filenames="HSA00000109759000023.png"\; state="\{\{state\}\}">V</figure-callout>}1=\frac{4096}{16}=256$

Observe sinusoidal wave positive maximal value and can find out that to the waveform in the negative peaked half period near zero-crossing point slope of a curve is much larger than near the slope of a curve peak value, then

V2-V1＞256

$R=\frac{1}{V2-\mathrm{<figure-callout\; id="1"\; label="V"\; filenames="HSA00000109759000023.png"\; state="\{\{state\}\}">V</figure-callout>}1}\&times;T_{/\mathrm{AD}}<\frac{1}{256}\&times;T_{/\mathrm{AD}}=\frac{1}{256}\&times;\frac{1}{32}\&times;1\mathrm{\&mu;s}=0.122\mathrm{ns}$

Referring to Fig. 5, hyperacoustic transmission time is:

$T=T_{\mathrm{ZD}}-T_{\mathrm{QD}}=N\&times;\frac{1}{F_{A/D}}+\frac{1}{V2-\mathrm{<figure-callout\; id="1"\; label="V"\; filenames="HSA00000109759000023.png"\; state="\{\{state\}\}">V</figure-callout>}1}\&times;T_{/\mathrm{AD}}\&times;V1-T_{\mathrm{QD}}$

Because the pairing moment of ultrasonic transmission start time can accurately be confirmed; Then the resolution of ultrasonic transmission time measurement depend on the ultrasonic transmission end time corresponding resolution constantly, then the resolution of ultrasonic transmission time measurement is less than 0.122 nanosecond.Being installed in the transducer E1 at body two ends and the distance between the E2 fixes; According to recording the travel-time of ultrasound wave between transducer E1 and E2; Be combined under the different temperatures with different medium in hyperacoustic speed, just can calculate the temperature of temperature sensor.For example, hyperacoustic speed is 344 meter per seconds in the time of 20 ℃, and hyperacoustic speed is 344.6 meter per seconds in the time of 21 ℃, if the distance between transducer E1 and the E2 is 0.3 meter, then hyperacoustic transmission time is 8.7209 * 10 in the time of 20 ℃ ^-4Second, hyperacoustic transmission time is 8.7057 * 10 in the time of 21 ℃ ^-4Second, hyperacoustic transmission time difference is 1.52 * 10 in the time of 21 ℃ and 20 ℃ the time ^-6Second.As stated, the resolution of ultrasonic transmission time measurement is superior to 1.0 * 10 ^-9Second, can realize that then resolution is superior to 0.001 ℃ temperature survey.

Claims (4)

1. method with the ultrasonic technology precisely measuring temperature; It is characterized in that: said method is ultrasonic transducer E1 and ultrasonic transducer E2 to be installed in relatively two ends constitute a ultrasonic temperature sensor in the pipe of an airtight withstand voltage body that is full of ultrasonic medium; With central processing unit CPU control on-site programmable gate array FPGA sine wave output drive signal; Let signal input to said ultrasonic transducer E1 through D/A change-over circuit and power amplification circuit successively, convert input signal to mechanical vibration by said ultrasonic transducer E1 and produce ultrasonic signal;

Said ultrasonic transducer E2 receives the ultrasonic signal that said ultrasonic transducer E1 sends; And output ultrasonic wave echoed signal; By filtering circuit the ultrasonic echo signal that ultrasonic transducer E2 sends is carried out filtering; After being amplified by amplifying circuit, by the A/D change-over circuit echoed signal is sampled, sampled data is stored in earlier in the memory block that is configured in the FPGA again;

After sampling is accomplished; Central processing unit CPU is at first launched hyperacoustic data according to FPGA and is confirmed the pairing moment of ultrasonic propagation time starting point; Read the A/D sampled data of ultrasonic echo signal then in the FPGA; Accurately calculate the pairing moment of ultrasonic propagation time terminal point through the segmentation interpolation algorithm, and then accurately confirm the transmission time of ultrasound wave between two transducer E1, E2; CPU is according to ultrasound wave different transmission times between two ultrasonic transducer E1 and the E2 in the ultrasonic temperature sensor body then, be combined under the different temperatures with different medium in hyperacoustic transmission speed, accurate Calculation obtains the temperature of temperature sensor;

The said pairing moment of acoustic transit time starting point is got the zero crossing moment corresponding of last that ripple of FPGA emission ultrasonic signal;

The segmentation interpolation algorithm of the terminal point in said calculating travel-time is: according to the A/D sampled signal of the ultrasonic echo of storing among the FPGA, at first confirm the maximum interior waveform of that cycle of peak amplitude in the echoed signal; Confirm the pairing moment of former and later two sampled points of zero crossing then; Be benchmark with former and later two sampled points of zero crossing at last, sampled point segmented, confirm the pairing moment of echoed signal zero crossing, i.e. the pairing moment of ultrasonic propagation time terminal point with fit method.

2. the method with the ultrasonic technology precisely measuring temperature according to claim 1 is characterized in that: said transducer E1 and E2 are piezoelectric transducers.

3. high-precision ultrasonic temperature measuring set of realizing claim 1 or 2 said methods, it is characterized in that: it comprises ultrasonic transducer E1, ultrasonic transducer E2, D/A change-over circuit, power amplification circuit, signal amplification circuit, filtering circuit, A/D change-over circuit, on-site programmable gate array FPGA and central processing unit CPU;

Said ultrasonic transducer E1 and ultrasonic transducer E2 are installed in the two ends of an airtight withstand voltage body relatively, are full of ultrasonic medium between two transducers;

Said central processing unit CPU connects on-site programmable gate array FPGA; Control on-site programmable gate array FPGA sine wave output drive signal; One tunnel output of on-site programmable gate array FPGA connects the D/A change-over circuit, by the D/A change-over circuit said sine wave drive signal is changed, and the D/A change-over circuit connects power amplification circuit again; Signal is amplified; Power amplification circuit is connected with ultrasonic transducer E1, and signal is inputed to said ultrasonic transducer E1, and this ultrasonic transducer E1 converts input signal to mechanical vibration and produces ultrasonic signal;

Said ultrasonic transducer E2 receives the ultrasonic signal that said ultrasonic transducer E1 sends; Convert mechanical vibration into electric signal; The output ultrasonic wave echoed signal; And through with its amplifying circuit that is connected successively, filtering circuit and A/D change-over circuit, make said ultrasonic echo signal after amplification, filtering and A/D conversion, input to on-site programmable gate array FPGA successively;

Said on-site programmable gate array FPGA sample simultaneously sine wave drive signal and the ultrasonic echo signal of input of output, and sampled data left in the internal memory;

Said central processing unit CPU reads sampled data from the on-site programmable gate array FPGA internal memory, accurately calculate the pairing moment of ultrasonic propagation time terminal point through the segmentation interpolation algorithm; Then, confirm the pairing moment of ultrasonic propagation time starting point, thereby accurately confirm the transmission time of ultrasound wave between two transducer E1, E2 according to the sine wave drive signal of output; Last CPU is according to ultrasound wave different transmission times between two transducer E1, the E2 in the ultrasonic temperature sensor body, be combined under the different temperatures with different medium in hyperacoustic transmission speed, accurate Calculation obtains the temperature of temperature sensor;

The said pairing moment of acoustic transit time starting point is got the zero crossing moment corresponding of last that ripple of FPGA emission ultrasonic signal;

The segmentation interpolation algorithm of the terminal point in said calculating travel-time is: according to the A/D sampled signal of the ultrasonic echo of storing among the FPGA, at first confirm the maximum interior waveform of that cycle of peak amplitude in the echoed signal; Confirm the pairing moment of former and later two sampled points of zero crossing then; Be benchmark with former and later two sampled points of zero crossing at last, sampled point segmented, confirm the pairing moment of echoed signal zero crossing, i.e. the pairing moment of ultrasonic propagation time terminal point with fit method.

4. high-precision ultrasonic temperature measuring set according to claim 3 is characterized in that: said transducer E1 and E2 are piezoelectric transducers.

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