CN101509942A - Ultrasonic transducer frequency response characteristic detecting method - Google Patents

Abstract

The invention provides a detection method for the frequency response characteristic of an ultrasonic transducer, which is based on that a multiple orthogonal frequency measurement signal can quickly detect the frequency response characteristic of the ultrasonic transducer, and comprises the following steps of: initializing frequency parameter; generating an actuating signal of the ultrasonic transducer; measuring the response of the ultrasonic transducer; calculating the frequency response characteristic of the ultrasonic transducer at the testing frequency point; and calculating the frequency response characteristic of the transducer within the given frequency range. The method is characterized in that: testing signals of a plurality of testing frequency points are adopted for one time, and the frequency response characteristic of the transducer at the frequency point is calculated according to the orthogonality of the testing signal among different frequency points, thus quickly and effectively measuring the frequency response characteristic of the ultrasonic transducer, having the advantages of fast detection speed and simple realization and the like, not only being suitable for various occasions requiring fast detection of the frequency characteristic of the transducer, but also being applicable to the fast detection of the frequency response characteristic of other electrical products.

Description

A kind of detection method of ultrasonic transducer frequency response characteristic

Technical field

The present invention relates to a kind of ultrasonic transducer frequency response characteristic detection technique, particularly a kind of ultrasonic transducer frequency response characteristic method for quick based on many orthogonal frequencies measuring-signal.

Background technology

Along with development of science and technology, ultrasonic technology has been widely used in aspects such as detection, medical diagnosis, ranging and range rate, cleaning, welding, rubble, in fields such as medical science, military affairs, industry, agricultural boundless application prospect and potentiality is arranged.

Ultrasonic transducer is one of Primary Component in the ultrasonic system, because ultrasonic transducer commonly used has narrower passband, therefore the frequency accuracy to pumping signal requires than higher, have only when the frequency of pumping signal is mated with the centre frequency of ultrasonic transducer exactly, transducer just can reach best power output effect, otherwise the output power of transducer will sharply descend, and be difficult to reach designing requirement.Therefore, how can accurately detect frequency response characteristic, particularly its centre frequency, the passband equifrequent parameter of transducer, be important link in the production, assembling, debugging, maintenance of ultrasonic system.

Ultrasonic transducer frequency response characteristic detection method commonly used at present is to adopt the mode of frequency sweeping, promptly produce constant amplitude simple signal that frequency changes within the specific limits as excitation, determine its frequency characteristic by measuring the output of ultrasonic transducer under the pumping signal of different frequency by frequency generator.The advantage of sweep frequency detection method is that principle is simple, realize easily, deficiency is that detection speed is slow, because it need scan a plurality of test frequency points with the interval of setting one by one in certain scope, because there is remained shock in ultrasonic transducer, the stable factors such as time that need of metering circuit, the detection of each Frequency point all needs to expend the regular hour, cause the detecting instrument processing speed slower, for example, suppose that swept frequency range is 40kHz, every 20Hz a test frequency point is set, needs 20ms the detection time of each Frequency point, then need 40000Hz/20Hz * 20ms=40000ms=40s the detection time of a frequency response characteristic.Along with the raising of automaticity, now the running speed of electro-acoustic product production line is very fast, and is also more and more higher to the requirement of the detection efficiency of checkout equipment on the line and speed.Transducer frequency response characteristic pick-up unit based on the frequency sweep mode is slower owing to detection speed, therefore can only be used for the sampling observation of a small amount of transducer, can't be applied to the online full inspection on the large-scale production line, bring certain difficulty for the total quality control in the ultrasonic transducer production run, also be unfavorable for using simultaneously producer and in process such as stock up, each ultrasonic transducer carried out quality inspection.

Summary of the invention

Exist speed slow at the sweep-frequency B ultrasonic transducer frequency response characteristic detection method that generally adopts at present, be unfavorable for that ultrasonic transducer is in production, full inspection in the process such as stock up, thereby influence the shortcoming of production quality control, the invention provides a kind of detection method of ultrasonic transducer frequency response characteristic, this method is based on many orthogonal frequencies measuring-signal energy fast detecting ultrasonic transducer frequency response characteristic, the characteristics of this method are once to adopt the test signal of a plurality of test frequency points, the frequency response characteristic of transducer on this Frequency point calculated in the orthogonality between the different frequency point by test signal, can fast and effeciently measure the frequency response characteristic of ultrasonic transducer, compare with traditional frequency sweep method that to have a detection speed fast, realize advantages such as simple, not only be fit to the occasion of various needs fast detecting transducer frequency characteristics, and also can be used for the frequency response characteristic fast detecting of other electric equipment products.

Quick ultrasonic transducer frequency response characteristic detection method based on many orthogonal frequencies pumping signal provided by the invention specifically comprises following steps:

1, initialization frequency parameter:, set the lower frequency limit f that detects according to given frequency measurement scope and frequency measurement accuracy _Min, upper limiting frequency f _MaxWith frequency interval Δ f, wherein closed interval [f _Min, f _Max] cover given frequency measurement scope, Δ f be less than or equal to given frequency measurement accuracy, and f _Min=K ₁Δ f, f _Max=K ₂Δ f, K ₁, K ₂Be positive integer and K ₁＜K ₂

2, produce the pumping signal of ultrasonic transducer: produce pumping signal $e\left(t\right)=A\underset{k=K_1}{\overset{K_2}{\mathrm{\Σ}}}\cos [2\mathrm{\π}{f}_{k}t+{\mathrm{\φ}}_k],$ And, give ultrasonic transducer to be tested, wherein f by after the power amplifier amplification _k=k Δ f, K ₁＜k＜K ₂, being a plurality of test frequency points to be detected, A is a constant, φ _kPhase place for sinusoidal component.

3, measure the response of ultrasonic transducer: measure the variation of ultrasonic transducer voltage or electric current under the pumping signal of step 2, obtain measuring-signal y (t), Measuring Time is not less than T=1/ Δ f.

4, calculate the frequency response characteristic of ultrasonic transducer at test frequency point: the transducer frequency response characteristic on the test frequency point fl=l Δ f adopts following formula directly to calculate:

$Y\left(f_l\right)={\∫}_0^{\mathrm{mT}}y\left(t\right)\cos \left(2\mathrm{\π}{f}_{l}t\right)\mathrm{dt}---\left(1\right)$

T=1/ Δ f wherein, K ₁＜l＜K ₂, m is a positive integer.

5, calculate the frequency response characteristic of transducer in given frequency range: to Y (f _l) carry out normalization and obtain Y (f _l), utilize Y (f _l) carry out interpolation arithmetic, obtain the frequency response characteristic Y (f) of transducer arbitrary frequency point in given frequency range.

By the sinusoidal component phase in the suitable selection step 2 _k, can avoid pumping signal spike pulse to occur, circuit can more effectively be worked.φ _kCan adopt following method to set:

(1) for each φ _k, in interval [π, π) a plurality of candidate values of middle setting;

(2) calculate φ _kWhen selecting different candidate values to make up, the peak value and the mean value of pumping signal e (t) absolute value;

(3) select the φ of the ratio minimum of the peak value that makes pumping signal e (t) absolute value and mean value _kThe combination of candidate value is as the φ that sends in the pumping signal _k

φ in the step 2 _kCan also adopt following method to set:

(1) produces many group φ at random _k, and calculate the peak value of corresponding pumping signal e (t) absolute value and the ratio of mean value;

(2) select one group of φ of the ratio minimum of the peak value that makes pumping signal e (t) absolute value and mean value _kAs the φ that sends in the pumping signal _k

Transducer can also adopt the method for fast fourier transform to calculate in the frequency response characteristic of test frequency point in the above-mentioned steps 4, and method is:

(1) y (t) is carried out mould/number conversion and obtains discrete series y[n], and be 2 to its zero padding to length ^P, wherein

L is y[n] length.

(2) sequence after the zero padding is done 2 ^PThe fast fourier transform of point obtains $f_l=\frac{f_s}{2^P}$ Frequency response characteristic Y (the f of place's transducer _l), f wherein _sBe sample frequency.

Transducer is in the calculating of test frequency dot frequency response characteristic in the above-mentioned steps 4, the method that can adopt formula (1) and fast fourier transform to combine, the operand that makes formula (1) when the number of given test frequency point is during less than the operand of fast fourier transform, employing formula (1) is calculated, otherwise then adopts fast fourier transform to calculate.

In the above-mentioned steps 5, can adopt multistage measuring-signal y (t) inequality to come frequency response characteristic Y (f) to calculate to transducer, and get its result on average be used as final estimated value to Y (f).

Compared with prior art, usefulness of the present invention is that detection speed is fast, because the test signal of each test frequency point is produced simultaneously, not needing one by one, Frequency point carries out sweep measurement, therefore after the pumping signal input is stable, can one-time detection go out the frequency response characteristic of ultrasonic transducer in given frequency range, significantly reduce required detection time, be fit to very much the detection of extensive continuous-flow type, can be advantageously used in producing, the full inspection of transducer when stocking up, more reliable total quality control means are provided.Frequency response characteristic method for quick provided by the invention not only can be used to detect the fast detecting of ultrasonic transducer frequency response characteristic, can also be widely used in the frequency response characteristic fast detecting of other electric equipment products.

Description of drawings

Fig. 1 is the hardware block diagram of the embodiment of the invention

Fig. 2 is embodiment of the invention ultrasonic transducer frequency response characteristic testing process figure

Embodiment

Below by a preferred embodiment of the present invention, specify embodiments of the present invention.

The hardware configuration of present embodiment as shown in Figure 1, by signal processing module, the A/D modular converter, the D/A modular converter, driver module, output/output interface module constitutes jointly, wherein signal processing module and A/D modular converter, the D/A modular converter is connected with the data input/output module, finish the generation of many orthogonal frequencies pumping signal, the calculating of transducer frequency response characteristic, running parameter is set, the function of testing result output, in the foregoing description, this module is made of dsp chip and peripheral circuit thereof, in further embodiments, dsp chip also can replace with the MCU flush bonding processor; Data output/load module is made of jointly display screen, keyboard controller, keyboard, warning circuit, usb circuit, wherein display screen provides the interface for user's operation, keyboard controller and keyboard are used to receive user's setting and instruction, warning circuit is used for warning to the staff when unusual detecting product, usb circuit is used to connect outer computer, so that the staff collects data, carries out software upgrading or carries out centralized control by computing machine; The D/A modular converter is connected with driver module with signal processing module, is converted to the pumping signal of simulation in order to the digital broadband pumping signal that signal processing module is produced, and in the foregoing description, the D/A modular converter adopts D/A conversion chip and peripheral circuit thereof to constitute; The A/D modular converter is connected with the voltage detecting point of signal processing module and transducer, be converted to digital voltage signal in order to analog voltage signal with transducer, and send signal processing module to and carry out analyzing and processing, in the foregoing description, the A/D modular converter adopts A/D conversion chip and peripheral circuit thereof to realize; Driver module is connected with the ultrasonic transducer that needs to detect with the D/A modular converter, the simulation wideband excitation signal amplification rear drive ultrasonic transducer that the D/A modular converter is sent carries out work, in the foregoing description, adopted power amplification chip and peripheral circuit thereof to constitute.

Above-mentioned hardware configuration is to be used to detect whether satisfactory equipment of transducer frequency response characteristic on the ultrasonic transducer production line, the ultrasonic transducer produced is during through above-mentioned this equipment, manually or automatically be connected to the test access point of this equipment, detect by the frequency response characteristic of the said equipment ultrasonic transducer, and with the regulation nominal value compare, when the frequency response parameter of ultrasonic transducer is undesirable, the said equipment provides alarm signal, by manually or automatically the transducer that falls short of specifications being taken out production line.The present invention is very fast to the detection speed of frequency response characteristic, therefore can each product on the production line all be detected.

In the present embodiment, signal processing module is controlled the work of other modules by software wherein, adopts flow process shown in Figure 2 to come the transducer on the production line is detected:

1, software and hardware initialization: after the foregoing description start, at first carry out the initial work of software and hardware, finish the self check of each module and/or reset.

2, set detected parameters: the user according to actual needs, by keyboard the parameter that need detect is set, for example, setting needs the parameter used (for example in the precision of the scope of index (as the standard value of centre frequency, passband, Q value etc. and tolerable error range etc.), frequency measurement of qualified transducer frequency response characteristic and frequency measurement and the some other computation process, the result of calculation that adopts how many times to measure fragment averages, to obtain final frequency response characteristic estimated value etc.).Signal processing module is selected suitable lower frequency limit f according to the scope of the given frequency measurement of user and the precision of frequency measurement _Min, upper limiting frequency f _MaxWith frequency interval Δ f, the setting principle of these three parameters is: [f _Min, f _Max] cover given frequency measurement scope, Δ f be less than or equal to given frequency measurement accuracy, and f _Min=K ₁Δ f, f _Max=K ₂Δ f, K ₁, K ₂Be positive integer and K ₁＜K ₂The user also can be by keyboard directly to lower frequency limit f _Min, upper limiting frequency f _MaxF sets with the frequency interval Δ.

3, produce pumping signal: produce pumping signal $e\left(t\right)=A\underset{k=K_1}{\overset{K_2}{\mathrm{\Σ}}}\cos [2\mathrm{\π}{f}_{k}t+{\mathrm{\φ}}_k],$ F wherein _k=k Δ f, K ₁＜k＜K ₂, being a plurality of test frequency points to be detected, A is a constant, φ _kBe the phase place of sinusoidal component, and by giving ultrasonic transducer to be tested after the power amplifier amplification.Because signal processing module is a digital device, therefore produce the pumping signal of numeral, be converted into simulating signal by the D/A modular converter again.Digital stimulus signal can adopt following formula to calculate and produce:

$e\left(n\right)=\underset{k=K_1}{\overset{K_2}{\mathrm{\Σ}}}A\cos [2\mathrm{\πkn}\·\mathrm{\Δf}/f_s+{\mathrm{\φ}}_k]$

F wherein _sBe sample frequency.

φ _kBe provided with can influence the waveform of pumping signal e (t), change the peak value of e (t) absolute value and the ratio of mean value, might and detect the generation harmful effect to the emission of signal.For example, as all φ _kAll be set at 0 o'clock, e (t) signal shows as one group of high-amplitude, very short pulse signal of duration, under identical emissive power, cause the saturated or overload of some devices such as D/A, A/D converter, transducer easily, the short duration has also increased the difficulty of signals collecting, analysis, therefore is necessary φ _kReasonably be provided with, its setting principle is the ratio minimum that as far as possible makes the peak value and the mean value of e (t) absolute value.In the foregoing description, the user can adopt two kinds of methods to come φ _kBe provided with, first method is to adopt the precalculated method of off-line, behind the given various frequency parameters of user, precomputes one group of more excellent φ on computers _kBe worth, and be sent to signal processing module by USB interface.φ on the computing machine _kThe estimation of value adopts following steps to carry out:

(1) for each φ _k, in interval [π, π) a plurality of candidate values of middle setting.In the foregoing description, each φ _k8 candidate values are set $\{-\mathrm{\π},-\frac{3}{4}\mathrm{\π},-\frac{1}{2}\mathrm{\π},-\frac{1}{4}\mathrm{\π},0,\frac{1}{4}\mathrm{\π},\frac{1}{2}\mathrm{\π},\frac{3}{4}\mathrm{\π}\};$

(2) calculate each φ _kWhen selecting different candidate values to make up, the peak value of e (t) absolute value and the ratio of mean value;

(3) at all φ _kIn the candidate value combination, select the φ of the ratio minimum of the peak value that makes pumping signal e (t) absolute value and mean value _kThe combination of candidate value is as the φ that sends in the pumping signal _k

In the foregoing description, φ _kCan also adopt another kind not by computing machine, by the automatic method to set up that signal processing module is finished, its step is as follows:

(1) produces many group φ at random _k, and calculate the peak value of corresponding pumping signal e (t) absolute value and the ratio of mean value; The generation of random number can be adopted pseudo random number algorithm such as congruence method.

(2) select that group φ of the ratio minimum of the peak value that makes pumping signal e (t) absolute value and mean value _kAs the φ that sends in the pumping signal _k

The above-mentioned digital stimulus signal that signal processing module produces is converted to the pumping signal of simulation by the D/A modular converter, and after the power amplifier module device amplifies, outputs to test access point.

Whether 4, detect and to have transducer to insert: the voltage signal of test access point is converted to input signal processing module after the digital signal by the A/D modular converter, signal processing module can change and determined whether that transducer inserts test access point by detecting current level, if there is transducer to insert, then carry out the detection of frequency response characteristic, otherwise then wait for till having transducer to insert.

5, the measuring-signal of record a period of time: after detecting the transducer access, signal processing module is noted the measuring-signal y[n of a period of time], the duration of tracer signal is not less than 1/ Δ f, and in the preferable implementation method, the duration of tracer signal is much larger than 1/ Δ f.The y[n that signal processing module is inequality according to the setting recording multistage of preliminary examination].

6, calculate the frequency response characteristic of transducer: after the measuring-signal record finishes, can carry out the calculating of transducer frequency response characteristic.This calculating specifically can be divided into two steps again:

(1) calculate the frequency response characteristic of transducer at test frequency point: in the foregoing description, the amplitude of test frequency point can adopt the method for direct calculating or fast fourier transform to calculate.Directly the amplitude of calculating test frequency point has been utilized the orthogonality of sinusoidal component in the pumping signal, and according to the definition of frequency response characteristic, measuring-signal y (t) can be expressed as:

$y\left(t\right)=A\′\underset{k=K_1}{\overset{K_2}{\mathrm{\Σ}}}Y\left(f_k\right)\cos [2\mathrm{\πk\Δft}+{\mathrm{\φ}}_k^{\′}]$

Y (f wherein _k) put f for transducer at test frequency _kThe place frequency response characteristic, A ' and

For be carried on the transducer, through sinusoidal component amplitude and phase place after the power amplification.Orthogonality according to sinusoidal signal has

${\∫}_0^{\mathrm{mT}}y\left(t\right)\cos \left(2\mathrm{\πl\Δft}\right)\mathrm{dt}$

$={\∫}_0^{\mathrm{mT}}\{A\′\underset{k=K_1}{\overset{K_2}{\mathrm{\Σ}}}Y\left(f_k\right)\cos [2\mathrm{\πk\Δft}+{\mathrm{\φ}}_k^{\′}]\cos \left(2\mathrm{\πl\Δft}\right)\mathrm{dt}\}$

$={\∫}_0^{\mathrm{mT}}\left\{\frac{A\′}{2}\underset{k=K_1}{\overset{K_2}{\mathrm{\Σ}}}Y\left(f_k\right)\{\cos [2\mathrm{\π}(k-l)\mathrm{\Δft}+{\mathrm{\φ}}_k^{\′}]+\cos [2\mathrm{\π}(k+l)\mathrm{\Δft}+{\mathrm{\φ}}_k^{\′}]\}\mathrm{dt}\right\}$

$=\frac{A\′}{2}Y\left(f_l\right)$

T=1/ Δ f wherein, K ₁＜l＜K ₂, m is a positive integer.If therefore ignore the influence of constant coefficient A ', test frequency point f _lTransducer frequency response characteristic on the=l Δ f is

$Y\left(f_l\right)={\∫}_0^{\mathrm{mT}}y\left(t\right)\cos \left(2\mathrm{\π}{f}_{l}t\right)\mathrm{dt}$

For the digital signal in the signal processing module, the corresponding calculated formula is:

$Y\left(f_l\right)=\underset{n=0}{\overset{N}{\mathrm{\Σ}}}y\left[n\right]\cos (2\mathrm{\πn}\·f_l/f_s)$

Wherein

And N≤L, L are y[n] length, K ₁＜k＜K ₂, m is a positive integer.

Adopt fast fourier transform to calculate the frequency response characteristic of each test frequency point, at first will be at y[n] back benefit 0 to length is 2 ^P, wherein

L is y[n] length, be 2 to length then ^PNew sequence make fast fourier transform, obtain $f_l=\frac{f_s}{2^P}$ Frequency response characteristic Y (the f of place's transducer _l).

Above-mentioned two kinds of computing method all can independently be used for estimating the frequency response characteristic of transducer at test frequency point place, in order to utilize the advantage of two kinds of methods more fully, adopted direct calculating and fast fourier transform to calculate the mode that combines in the foregoing description, when MN＜2 ^P.P the time, adopt direct account form, otherwise adopt the fast fourier transform mode, wherein M is the frequency test point number of required calculating in the direct calculation method.

(2) to Y (f _l) carry out amplitude normalization, obtain normalized frequency response characteristic Y (f _l), utilize Y (f then _l) carry out interpolation arithmetic, obtain the frequency response characteristic Y (f) of transducer arbitrary frequency point in given frequency range.Interpolation can adopt several different methods, for example linear interpolation method etc.

In the foregoing description,, can adopt repeatedly the mean value that calculates measured value: record multistage y[n as final frequency response characteristic in order to increase the reliability of testing result], calculate every section y[n respectively] Y (f), get its mean value then.

7, the transducer frequency response characteristic that utilizes step 6 to obtain, calculate the frequency parameter that needs detection, for example centre frequency, passband, Q value etc., and compare with the given standard value of user, if in error range, then this transducer performance is normal, and after transducer to be detected and test access point disconnected and being connected, commentaries on classics step 4 was proceeded the detection of next transducer; If error exceeds given scope, then this transducer performance is unusual, signal processing module sends warning by alarm module, after manually or automatically the transducer that falls short of specifications being taken out production line, changes the detection that step 4 continues to proceed next transducer.

In the foregoing description, display screen provides the interface of setting for the user, and can implement to reflect the result of detection in testing process.The foregoing description can also be connected with computing machine by USB interface, so that staff's on-site collection data, carry out software upgrading or carry out centralized control by computing machine.

Claims (7)

1, a kind of detection method of ultrasonic transducer frequency response characteristic is characterized in that comprising the steps:

(1) initialization frequency parameter:, set the lower frequency limit f that detects according to given frequency measurement scope and frequency measurement accuracy _Min, upper limiting frequency V _MaxWith frequency interval Δ f, wherein closed interval [f _Min, f _Max] cover given frequency measurement scope, Δ f be less than or equal to given frequency measurement accuracy, and f _Min=K ₁Δ f, f _Max=K ₂Δ f, K ₁, K ₂Be positive integer and K ₁＜K ₂

(2) pumping signal of generation ultrasonic transducer: produce pumping signal $e\left(t\right)=A\underset{k=K_1}{\overset{K_2}{\mathrm{\Σ}}}\cos [2\mathrm{\π}{f}_{k}t+{\mathrm{\φ}}_k],$ And, give ultrasonic transducer to be tested, wherein f by after the power amplifier amplification _k=k Δ f, K ₁＜k＜K ₂, be a plurality of test frequency points to be detected; A is a constant, φ _kPhase place for sinusoidal component;

(3) measure the response of ultrasonic transducer: measure the variation of ultrasonic transducer voltage or electric current under the pumping signal of step (2), obtain measuring-signal y (t), Measuring Time is not less than T=1/ Δ f;

(4) calculate the frequency response characteristic of ultrasonic transducer: test frequency point f at test frequency point _lTransducer frequency response characteristic on the=l Δ f adopts following formula to calculate:

$Y\left(f_l\right)={\∫}_0^{\mathrm{mT}}y\left(t\right)\cos \left(2\mathrm{\π}{f}_{l}t\right)\mathrm{dt}$ ①

T=1/ Δ f wherein, K ₁＜l＜K ₂, m is a positive integer;

(5) calculate the frequency response characteristic of transducer in given frequency range: to Y (f _l) carry out normalization and obtain Y (f _l), utilize Y (f _l) carry out interpolation arithmetic, obtain the frequency response characteristic Y (f) of transducer arbitrary frequency point in given frequency range.

2, the detection method of ultrasonic transducer frequency response characteristic according to claim 1 is characterized in that by selecting the sinusoidal component phase in the step (2) _k, avoid pumping signal spike pulse to occur, φ _kAdopt following method to set:

(2.1) for each φ _k, in interval [π, π) a plurality of candidate values of middle setting;

(2.2) calculate φ _kWhen selecting different candidate values to make up, the peak value and the mean value of pumping signal e (t) absolute value;

(2.3) select the φ of the ratio minimum of the peak value that makes e (t) absolute value and mean value _kThe combination of candidate value is as the φ that sends in the pumping signal _k

3, the detection method of ultrasonic transducer frequency response characteristic according to claim 1 is characterized in that the φ in the step (2) _kAdopt following method to set:

(3.1) produce many group φ at random _k, and calculate the peak value of corresponding pumping signal e (t) absolute value and the ratio of mean value;

(3.2) select one group of φ of the ratio minimum of the peak value that makes pumping signal e (t) absolute value and mean value _kAs the φ that sends in the pumping signal _k

4, according to the detection method of claim 2 or 3 described ultrasonic transducer frequency response characteristics, it is characterized in that in the step (5), adopt multistage measuring-signal y (t) inequality to come frequency response characteristic Y (f) to calculate to transducer, and get its result on average be used as final estimated value to Y (f).

5, the detection method of ultrasonic transducer frequency response characteristic according to claim 4 is characterized in that transducer adopts the method for fast fourier transform to calculate in the frequency response characteristic of test frequency point in the step (4), is specially:

(4.1) y (t) is carried out mould/number conversion and obtains discrete series y[n], and be 2 to its zero padding to length ^P, wherein L is y[n] length;

(4.2) sequence after the zero padding is done 2 ^PThe fast fourier transform of point obtains $f_l=\frac{f_s}{2^P}$ Frequency response characteristic Y (the f of place's transducer _l), f wherein _sBe sample frequency.

6, the detection method of ultrasonic transducer frequency response characteristic according to claim 5, it is characterized in that ultrasonic transducer is in the calculating of test frequency dot frequency response characteristic in the step (4), the method that 1. the employing formula combines with fast fourier transform, when the number of given test frequency point makes formula operand 1. less than the operand of fast fourier transform, 1. the employing formula is calculated, otherwise then adopts fast fourier transform to calculate.

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