CN104949751A - Intelligent acoustic velocity measurement experimental device and acoustic velocity measurement method - Google Patents

Abstract

The invention discloses an intelligent sound velocity measurement experiment device and a sound velocity measurement method, which belong to the field of physical experiment equipment and electronic information technology, and include a mechanical measurement device, a control processing circuit and a case; the mechanical measurement device is located on the case, and includes a fixing plate, Ultrasonic transmitting head, ultrasonic receiving head, vernier, main ruler, auxiliary ruler, mobile bracket, screw, handle, first gear, second gear, incremental encoder; the control processing circuit is located inside the chassis, and the control processing circuit On the one hand, it drives the ultrasonic transmitting head to emit ultrasonic waves; on the other hand, it processes the ultrasonic signals received by the ultrasonic receiving head, calculates the propagation speed of ultrasonic waves, and transmits information with peripheral devices. The intelligent sound velocity measurement experimental device proposed by the present invention is low in cost, simple in operation and high in precision, and does not need signal generators and oscilloscopes, two expensive instruments; in actual use, both the phase comparison method and the time difference method can be used to measure the sound velocity experiment.

Description

An intelligent sound velocity measurement experimental device and sound velocity measurement method

technical field

The invention relates to the field of physical experiment equipment and electronic information technology, in particular to a device for automatically recording and processing relevant data in sound velocity measurement experiments.

Background technique

The speed of sound is a physical quantity that describes the propagation characteristics of sound waves in a medium. Velocity of sound measurement technology has been widely used. The propagation of sound waves requires a medium, and the propagation speed of sound waves in the medium is related to factors such as the characteristics and state of the medium. Therefore, through the measurement of sound velocity, the characteristics and state changes of the measured medium can also be understood. It can be seen that the measurement of sound velocity has certain practical significance in actual production and life.

The sound velocity measurement experiment is also an important part of the university physics experiment teaching. However, the traditional sound velocity measurement device needs to combine the signal generator and the oscilloscope. low measurement accuracy.

Contents of the invention

In order to overcome the above-mentioned deficiencies in the prior art, the object of the present invention is to provide a kind of experimental device that does not need signal generator and oscilloscope, automatically records relevant data in the velocity of sound measurement, and concrete technical scheme is:

An intelligent sound velocity measurement experimental device, including a mechanical measurement device, a control processing circuit and a chassis;

The mechanical measuring device is located above the chassis, including a fixed plate, an ultrasonic transmitter, an ultrasonic receiver, a vernier, a main scale, a sub scale, a moving bracket, a lead screw, a handle, a first gear, a second gear, an incremental Encoder;

The fixing plate is fixed above the two ends of the chassis, the two ends of the main ruler are respectively fixed on the fixing plate and placed horizontally, a groove is arranged under the main ruler; the ultrasonic emitting head is fixed on the left side fixed plate; the lead screw passes through the moving bracket, the two ends of the lead screw are respectively fixed on the fixed plate, the lead screw is located below the main ruler and parallel to the main ruler; The moving bracket is perpendicular to the lead screw, the connection between the moving bracket and the screw is provided with threads, the upper end of the moving bracket is provided with a bump and a vernier, and the bump is snapped into the main scale In the groove below and can slide along the groove, the vernier can slide along the top of the main ruler, and the ultrasonic receiving head is installed at the lower end of the moving bracket, and the ultrasonic receiving head and the ultrasonic emitting head are on the same horizontal line Upper face facing installation;

The incremental encoder is fixed on the left fixed plate, the second gear is coaxially fixed with one end of the lead screw, the first gear meshes with the second gear, and the first gear is fixed on the shaft of said incremental encoder;

The handle is fixedly connected to the auxiliary ruler, and the auxiliary ruler is fixedly connected to the other end of the lead screw;

The control processing circuit is located inside the chassis. On the one hand, the control processing circuit drives the ultrasonic transmitting head to emit ultrasonic waves; information transfer between.

Further, the control processing circuit includes a microprocessor, a power amplifier, a band-pass filter, an automatic gain controller, an amplifier, a waveform shaping circuit, a phase difference comparison circuit and a filter capacitor; the band-pass filter, the automatic gain control The device, the amplifier, the waveform shaping circuit, the phase difference comparison circuit, the filter capacitor, the microprocessor and the power amplifier are connected in sequence, and the input end of the power amplifier is connected to the phase difference comparison circuit An input end of the waveform shaping circuit is connected to the microprocessor, an output of the power amplifier is connected to the ultrasonic transmitting head, and the ultrasonic receiving head is connected to the band-pass filter; The output of the quantitative encoder is connected to the microprocessor.

Further, the incremental encoder is located on the outside of the left fixing plate, and the first gear and the second gear are located on the inside of the left fixing plate.

Further, the handle and the auxiliary ruler are located on the outside of the right fixing plate.

Further, the peripheral equipment is arranged on the chassis body, including an indicator light, a liquid crystal display, a power switch, buttons, a signal output interface and a signal selection knob, a power amplifier output interface, and a receiving signal input interface; the indicator light , the liquid crystal display screen, the signal selection knob and the buttons are all connected to the microprocessor.

Further, the control processing circuit further includes a temperature detection module, the output of the temperature detection module is connected to the microprocessor, and the temperature detection module is used to detect the ambient temperature in real time.

Further, the microprocessor adopts STM32 single-chip microcomputer, the bandpass filter includes an operational amplifier OP07 and peripheral circuits, the automatic gain controller includes AD603 and peripheral circuits, and the amplifier includes operational amplifiers OP07 and peripheral circuits, the The waveform shaping circuit includes LM393 and peripheral circuits, the phase difference comparison circuit includes XOR gate 74LS86; the temperature detection module includes DS18B20.

Further, both ends of the lead screw are respectively connected to the fixed plate through bearings; the handle is fixedly connected to the auxiliary ruler through threads.

Based on the above-mentioned device, the present invention also proposes a method for measuring the velocity of sound, comprising the steps of:

Step 1: Calibrate the electronic scale after the device is initialized, so that the vernier is at the zero scale line of the main scale;

Step 2: the control processing circuit outputs a square wave signal s1 with a frequency of f, and the square wave signal drives the ultrasonic transmitter through a power amplifier to transmit ultrasonic waves with a frequency of f;

Step 3: The control processing circuit converts the ultrasonic signal received by the ultrasonic receiving head into an electrical signal in real time, and processes it into a square wave signal s3;

Step 4: Judge the phase difference between the square wave signal s1 and the square wave signal s3, if the phase difference is 0, record the coordinates of the ultrasonic receiving head;

Step 5: Shake the handle to make the ultrasonic receiving head move to the right, and when the phase difference between the square wave signal s1 and the square wave signal s3 is judged to be 0, record the coordinates of the ultrasonic receiving head;

Step 6: Repeat step 5 to record n+1 coordinates;

Step 7: The difference between two adjacent coordinates among the n+1 coordinates recorded in step 6 is the wavelength λ of the ultrasonic wave, and the ultrasonic velocity value is calculated according to the formula υ=f·λ.

Compared with prior art, the beneficial effect of the present invention is:

The traditional sound velocity measurement device needs to combine the signal generator and the oscilloscope, two kinds of expensive experimental instruments, and the experimental process has problems such as complicated operation process, time-consuming, error-prone, and low measurement accuracy; the intelligent sound velocity measurement experiment proposed by the present invention The device has low cost, simple operation and high precision; in actual use, both the phase comparison method and the time difference method can be used for sound velocity measurement experiments.

Description of drawings

Fig. 1 is the front view of intelligent sound velocity measurement experimental device of the present invention;

Fig. 2 is the perspective view of the intelligent sound velocity measurement experimental device of the present invention;

Fig. 3 is the block diagram of the control processing circuit in the intelligent sound velocity measurement experimental device of the present invention;

The functional block diagram of Fig. 4 signal selection output.

Marks in the figure, 1-signal selection knob, 2-signal output interface, 3-ultrasonic transmitter, 4-incremental encoder, 5-first gear, 6-second gear, 7-fixing plate, 8-ultrasonic Receiving head, 9-mobile bracket, 10-cursor, 11-screw, 12-main scale, 13-sub scale, 14-handle, 15-power switch, 16-chassis, 17-power amplifier output interface, 18-receiving Signal input interface, 19-buttons, 20-indicators, 21-LCD display.

Detailed ways

First statement: In the description of the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right" ", "vertical", "horizontal", "top", "bottom", "inner", "outer" and other indicated orientations or positional relationships are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of description The present invention and simplified description do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and thus should not be construed as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be interpreted as indicating or implying relative importance or implicitly specifying the quantity of indicated technical features. Thus, a feature defined as "first" and "second" may explicitly or implicitly include one or more of these features.

The present invention proposes an intelligent sound velocity measurement experimental device. The circuit part of the whole experimental device takes a microprocessor as the core, and the periphery is mainly composed of a power amplifier, a band-pass filter, an automatic gain controller, an amplifier, a waveform shaping circuit, a phase difference comparison circuit, It is composed of filter capacitor, temperature detection module, button 19, indicator light 20, liquid crystal display 21, etc. (as shown in FIG. 3 ). The microprocessor outputs a square wave signal s1 with a frequency of f, and drives the ultrasonic transmitting head 3 through a power amplifier to transmit ultrasonic waves with a frequency of f and a phase of α; the ultrasonic receiving head 8 receives ultrasonic waves with a phase of β, and converts the ultrasonic waves into electrical signals. The clutter in the electrical signal is filtered out by a filter; the automatic gain controller stabilizes the amplitude of the electrical signal; the amplifier amplifies the electrical signal; the waveform shaping circuit converts the electrical signal into a square wave signal s3. The square wave signals s1 and s3 are processed by the phase difference comparison circuit to output the rectangular wave electric signal s4; the electric signal s4 becomes the direct current signal s5 after passing through the filter capacitor; the microprocessor collects the voltage value of the electric signal s5 and converts it into a digital quantity, and judges the signal The phase difference between s1 and the signal s3; thereby judging the phase difference between the transmitted ultrasonic wave and the received ultrasonic wave. The buttons 19 include a menu button, an up button, a down button, and an OK button, and the buttons are used to switch the experiment mode and control the start and end of the experiment. The liquid crystal display 21 is used to display relevant data during the experiment. The indicator light 20 is used to indicate the state during the experiment.

As shown in Figures 1 and 2, the mechanical measurement part of the experimental device is located on the chassis 16, including a fixed plate 7, an ultrasonic transmitter 3, an ultrasonic receiver 8, a cursor 10, a main ruler 12, an auxiliary ruler 13, a mobile bracket 9, Lead screw 11, handle 14, first gear 5, second gear 6, incremental encoder 4; There are two fixed plates 7, which are respectively fixed above the two ends of the chassis 16, and the two ends of the main scale 12 are respectively fixed on the fixed On the plate 7, grooves are provided below the main chi 12, the leading screw 11 is perpendicular to the mobile support 9, and the two ends of the leading screw 11 pass through the mobile support 9 and are respectively fixed on the fixed plate 7 by bearings, and the ultrasonic transmitter 3 is fixed. On the left side fixed plate 7, the ultrasonic receiving head 8 and the vernier 10 are respectively fixed on the lower end and the upper end of the mobile bracket 9, there are threads in the mobile bracket 9 to cooperate with the lead screw 11, and the upper end of the lead screw is also provided with a bump, so Said projection snaps into the groove below the main ruler and can slide along the groove, the vernier can slide on the main ruler, and the rotation of the leading screw 11 can make the mobile bracket 9 move horizontally along the leading screw 11 direction. The handle 14 and the auxiliary chi 13 are screwed together, the auxiliary chi 13 is fixedly connected with the shaft at the right end of the leading screw 11, and shaking the handle 14 can drive the auxiliary chi 13 and the leading screw 11 to rotate together. The second gear 6 is installed on the lead screw 11, the second gear 6 is coaxially fixed with the left end of the lead screw 11, the rotation of the lead screw 11 drives the second gear 6 to rotate, and the incremental encoder 4 is fixed on the left fixed plate 7 On, the second gear 6 meshes with the first gear 5 installed on the shaft of the incremental encoder 4; the second gear 6 drives the first gear 5 to rotate, and the first gear 5 drives the shaft of the incremental encoder 4 to rotate; The microprocessor can calculate the angle rotated by the 4-axis of the incremental encoder by capturing the signals output by the 4 two-phase signal lines of the incremental encoder.

Before implementing the speed of sound measurement experiment, the ultrasonic transmitting head 3 needs to be connected to the power amplifier output interface 17 with a wire, and the power amplifier output interface 17 is connected to the power amplifier inside the chassis, and the ultrasonic receiving head 8 is connected to the receiving signal input interface 18 with a wire , the receiving signal input interface 18 is connected to the bandpass filter inside the chassis 16; and the experimental device is calibrated. After pressing the power switch 15, the experimental device is initialized, and after pressing the menu button in the button 19, the liquid crystal display 21 displays three modes: electronic ruler calibration, phase comparison method, and time difference method. Select the electronic ruler calibration mode by pressing the up button and down button and press the OK button to enter the calibration mode. The electronic scale calibration mode is as follows: shake the handle 14 to move the vernier 10 to the zero scale line of the main scale 12 and press the OK button, shake the handle 14 again to move the vernier 10 to the maximum scale line of the main scale 12, and press the OK button The calibration of the electronic ruler can be completed: when the handle 14 is turned clockwise, the handle 14 drives the auxiliary ruler 13 and the leading screw 11 to rotate clockwise, and the leading screw 11 drives the mobile bracket 9 to move left and right; the second gear 6 is installed on the leading screw 11 , the screw 11 rotates to drive the second gear 6 to rotate, the second gear 6 drives the first gear 5 to rotate, and the first gear 5 drives the shaft of the incremental encoder 4 to rotate; the incremental encoder 4 gives two square waves , The phase difference of the two square waves is 90 degrees, called A phase and B phase. The reading of the A-phase channel gives information related to the rotational speed. At the same time, the signal of the rotation direction is obtained by sequentially comparing the obtained B-phase channel signal with the A-phase channel signal. The microprocessor can calculate the angle and direction that the incremental encoder 4 rotates by capturing the signals output by the two-phase signal lines of the incremental encoder 4, thereby calculating the coordinates of the cursor 10 on the mobile support 9; When at the zero scale line of ruler 12, the distance between the ultrasonic transmitting head 3 and the ultrasonic receiving head 8 is a fixed value L, so when the ultrasonic receiving head 8 moves, the microprocessor can calculate the distance between the ultrasonic receiving head 8 and the ultrasonic receiving head 8 . The measuring range of the main scale 12 is 500mm, and the lead screw 11 turns a circle and the lead is p=1mm, that is, the handle 14 drives the lead screw 11 to turn a circle and the moving distance of the moving bracket 9 is 1mm; the resolution of the incremental encoder 4 is 1024P/ R, if the cursor 10 moves from the zero scale line to the maximum scale line, the microprocessor receives m A-phase pulses and m B-phase pulses from the incremental encoder 4, and the A-phase pulses are always ahead of the B-phase pulses 90 degrees, the microprocessor receives m pairs of pulses corresponding to the ultrasonic receiving head 8 moving 500mm. In an ideal state, the transmission error between the lead screw 11, the incremental encoder 4 and the first gear 5 and the second gear 6 is ignored, m=512000, there is a slight deviation in reality, and the reality shall prevail. If the microprocessor receives 1 phase A pulse and 1 phase B pulse, and the phase A is 90 degrees ahead of the phase B pulse, then the ultrasonic receiving head will move accordingly mm; the lead screw 11 turns a circle and the lead is p=1mm, and there are 100 scales on the auxiliary scale 13, so the resolution of the scale is The pitch circle diameter ratio n=1:1 of the first gear 5 and the second gear 6; then the resolution of the distance detection of this experimental device is: In the above, the microprocessor receives m A-phase pulses corresponding to the ultrasonic receiving head 8 moving 500mm; if the cursor 10 moves from the known X1 point line to the X2 point, the microprocessor receives the incremental encoder 4 n A-phase pulses and n B-phase pulses, and A-phase is always 90 degrees ahead of B-phase pulses, then the coordinates of point X2 are If the vernier 10 moves from the known X1 point line to the X3 point, the microprocessor receives the x pair of pulses from the incremental encoder 4, and the A phase always lags the B phase pulse by 90 degrees, then the coordinates of the X3 point are

The device can measure sound velocity by phase comparison method and time difference method.

Embodiment 1: phase comparison method

After the calibration is completed, press the menu button to enter the mode selection, select the phase comparison method by pressing the up button and down button, and then press the OK button to enter the phase comparison method mode for the sound velocity measurement experiment. After entering the phase comparison method, the microprocessor reads the temperature value t of the experimental environment output by the temperature detection module, and passes the formula Calculate the theoretical value of sound velocity, where υ ₀ =331.45m/s, T ₀ =273.15K, and the unit of t is Celsius. The current experimental ambient temperature and the theoretical value of the sound velocity at this temperature are displayed through the liquid crystal display screen 21 . Shake the handle 14 clockwise, the handle 14 drives the auxiliary ruler 13 and the screw 11 to rotate, and the rotation of the screw 11 drives the moving bracket 9 to move to the left until the cursor 10 on the moving bracket 9 reaches the zero mark of the main ruler 12 and press Confirm the key, and the microprocessor will set the current position coordinates as 0. At this time, the microprocessor outputs a square wave signal s1 with a frequency f, f=40kHz, which is fine-tuned according to the resonance frequency of the actual ultrasonic transmitting head 3 and ultrasonic receiving head 8 . Drive the ultrasonic transmitting head 3 through the power amplifier to transmit α ultrasonic waves with a frequency of f; the ultrasonic receiving head 8 receives the ultrasonic waves with a phase of β, and converts the ultrasonic waves into electrical signals; the band-pass filter filters out the clutter in the electrical signals; When the distance between the ultrasonic receiving head 8 and the ultrasonic emitting head 3 is different, resulting in different signal strengths received by the ultrasonic receiving head, the amplitude of the electrical signal output by the automatic gain controller will also be stable at a certain value. The amplifier amplifies the electrical signal; the waveform shaping circuit converts the electrical signal into a square wave signal s3. The signal s1 and the signal s3 are compared by the phase difference comparison circuit to output a rectangular wave electrical signal s4; the electrical signal s4 becomes an analog electrical signal s5 after being filtered by a capacitor; the microprocessor collects the voltage value of the analog electrical signal s5, and the internal A/ The D converter converts the analog electrical signal s5 into a digital quantity, and can calculate the phase difference between the signal s1 and the signal s3; thereby judging the phase difference between the transmitted ultrasonic wave and the received ultrasonic wave. At the same time, the microprocessor detects the coordinate value of the ultrasonic receiving head 8 in real time; when the handle 14 is shaken, when the ultrasonic receiving head 8 moves to the right, if the phase difference between the emitted ultrasonic wave and the received ultrasonic wave is 0 degrees, record the received ultrasonic wave at this time. The coordinate value of the head 8 is X0, and the indicator light 20 is turned on. Continue to shake the handle 14, the indicator light 20 goes out, and the ultrasonic receiving head moves to the right until the phase difference between the transmitted ultrasonic wave and the received ultrasonic wave is 0 degrees again, record the coordinates of the ultrasonic receiving head at this moment as X1, repeat the above operation, and record until n+ 1 coordinate. The difference between two adjacent coordinates is the wavelength λ of the ultrasonic wave with frequency f; the microprocessor uses the step-by-step method to calculate the sound velocity υ=f·λ; the theoretical value of sound velocity υ _t has been obtained when the device is initialized, and the microprocessor passes formula Computes the relative error of the sound velocity measurement. After the experiment, the liquid crystal display 21 displays the measured sound velocity value, and the ambient temperature, the theoretical value of sound velocity, the measured value of sound velocity, the relative error and the ultrasonic wavelength measured each time are checked at the beginning of the experiment by moving up and down buttons.

Embodiment 2: time difference method

After the calibration is completed, press the menu key to enter the mode selection, switch the time difference method by pressing the up button and the down button, and then press the OK button to enter the time difference method mode for the sound velocity measurement experiment. Shake the handle 14 clockwise, the handle 14 drives the auxiliary scale 13 and the screw 11 to rotate, the screw 11 rotates to make the moving bracket 9 move to the left, until the cursor 10 on the moving bracket 9 reaches the zero mark of the main scale 12 and press Confirm the button, the microprocessor sets the current coordinates to 0; the microprocessor transmits a series of square wave signals s6 of 8 cycles, and the square wave signal s6 drives the ultrasonic transmitting head 3 to transmit ultrasonic waves through the power amplifier, and the ultrasonic waves propagate for a certain distance, and are transmitted by the ultrasonic waves The receiving head 8 receives and converts it into an electrical signal, and the bandpass filter filters out the clutter in the electrical signal; the automatic gain controller makes the signal strength received by the ultrasonic receiving head even if the distance between the ultrasonic receiving head 8 and the ultrasonic transmitting head 3 is different. At different times, the amplitude of the electrical signal output by the automatic gain controller will also be stable at a certain value; the amplifier will amplify the electrical signal; the waveform shaping circuit will convert the electrical signal into a square wave signal s7; the output signal of the waveform shaping circuit is a string A square wave with 8 cycles; the microprocessor starts timing when it transmits the square wave of the fourth cycle, and stops timing when the microprocessor receives the fourth cycle of the square wave signal output by the waveform shaping circuit, and obtains the time value t, ignoring the propagation time of the signal in the circuit, t is the propagation time of the ultrasonic wave from the ultrasonic transmitting head 3 to the ultrasonic receiving head 8 . Move the cursor 10 to the zero scale line and press the OK button, and the microprocessor outputs the pulse train and starts timing, the microprocessor captures the signal output by the waveform shaping circuit and stops timing to obtain time t0, and uses t0 as the compensation time; the timing is completed Then the indicator light 20 is lighted; continue to shake the handle 14, the ultrasonic receiving head 8 moves to a certain position x ₁ , press the confirm button, the indicator light 20 goes out, the microprocessor outputs the pulse train again and starts timing, and the microprocessor captures The signal output by the waveform shaping circuit stops timing, obtains the time t1 and lights up the indicator light 20, then the ultrasonic propagation distance is the time T1 _{= t1} -t0 required for x1; repeat the above-mentioned operations, and measure n distances and n Time, (the value of n can be determined according to the actual situation); the microprocessor You can calculate the speed of sound υ _n and pass the formula Calculate the average of the speed of sound by formula Calculate the relative error. After the experiment is over, the liquid crystal display 21 displays the measured sound velocity value, and the ambient temperature, the theoretical value of sound velocity, the measured value of sound velocity, the relative error, and the distance x and time measured each time are checked by moving up and down buttons. t, and the linear equation with time t as the independent variable and distance x as the dependent variable obtained by curve fitting using the least square method.

When implementing the speed of sound measurement experiment, not only the position coordinates of the ultrasonic receiving head 8, the phase difference between the emitted ultrasonic wave and the received ultrasonic wave can be observed through the liquid crystal display 21 and the indicator light 20, but also the ultrasonic received wave can be read through the main scale 12 and the auxiliary scale 13. For the position coordinate information of the head 8, use wires to connect the oscilloscope to the signal output interface 2 to observe the transmitted signal, the electrical signal converted from the received ultrasonic wave, and the electric signal converted by the band-pass filter, automatic gain controller, amplifier, waveform shaping circuit, and phase difference. The output waveform after the comparison circuit is processed. There are 4 signal output interfaces 2, numbered 2-1, 2-2, 2-3, 2-4, 2-1 outputs the square wave signal output by the microprocessor and the sinusoidal signal after the filter processing, indicating that the ultrasonic wave is emitted 2-2 output the electrical signal converted from the ultrasonic signal received by the ultrasonic receiving head 8, 2-3 output the electrical signal output by the waveform shaping circuit and the phase difference comparison circuit through multi-channel analog switches, and 2-4 output the electrical signal with The electrical signal output by the pass filter, automatic gain controller, amplifier, and filter capacitor passes through multiple analog switches. Use the signal selection knob 1 (there are 2 signal selection knobs in total, signal selection knob A and signal selection knob B) to select the signal output by the signal output interface 2: the shaft of the signal selection knob 1 and the rotary encoding switch is fixed, and the rotary encoding switch It refers to a group of switching electronic components with regular and strict timing pulses. Through the cooperation with IC, it can perform functions such as increment, decrement, and page turning; the rotary encoding switch outputs two signals with a phase difference of 90 degrees, and the microprocessor Capturing the signal output by the rotary encoding switch can determine the position of the knob, and then control the multi-channel analog switch to open the corresponding channel and output the required signal.

Figure 4 is a functional block diagram of the signal selection output. The signal received by the ultrasonic receiving head 8, the signal output by the bandpass filter, the signal output by the automatic gain controller, and the output signal filtered by the filter capacitor are respectively connected to 4 independent input channels of the A road of the multi-channel analog switch A, The shared output channel of the A road of the multi-channel analog switch A is connected to 2-4 of the signal output interface 2, and the two selection input terminals of the multi-channel analog switch A are respectively connected to two input/output ports (IO ports) of the microprocessor; The signal output by the phase difference comparison circuit and the signal output by the waveform shaping circuit are respectively connected to two of the four independent input channels of the A channel of the multi-channel analog switch B, and the shared output channel of the A channel of the multi-channel analog switch B is connected to the signal output interface 2-3 of 2, the two selection input ends of the multi-channel analog switch B are respectively connected to two input/output ports (IO ports) of the microprocessor.

Described band-pass filter is made of operational amplifier OP07 and peripheral circuit, automatic gain controller is made of AD603 and peripheral circuit, amplifier is made of operational amplifier OP07 and peripheral circuit, waveform shaping circuit is made of LM393 and peripheral circuit, phase difference comparison circuit is made of The XOR gate is composed of 74LS86; the multi-channel analog switch is composed of 74HC4052, the temperature detection module is composed of DS18B20, and the microprocessor is STM32 single-chip microcomputer.

The above is only used to describe the technical solution of the present invention, and is not used to limit the protection scope of the present invention. It should be understood that any modifications, improvements and equivalent replacements will be made without departing from the essence and spirit of the present invention. All will fall within the protection scope of the present invention.

Claims (9)

1. An intelligent sound velocity measurement experimental device is characterized in that, comprising a mechanical measuring device, a control processing circuit and a cabinet (16); The mechanical measuring device is located above the chassis (16), and includes a fixed plate (7), an ultrasonic transmitting head (3), an ultrasonic receiving head (8), a vernier (10), a main ruler (12), an auxiliary ruler (13 ), mobile bracket (9), lead screw (11), handle (14), first gear (5), second gear (6), incremental encoder (4); The fixed plate (7) is fixed above the two ends of the cabinet (16), and the two ends of the main ruler (12) are respectively fixed on the fixed plate (7) and placed horizontally. There is a groove; the ultrasonic emitting head (3) is fixed on the left fixed plate (7); the leading screw (11) passes through the mobile bracket (9), and the two ends of the leading screw (11) respectively Fixed on the fixed plate (7), the lead screw (11) is located below the main scale (12) and parallel to the main scale (12); the moving bracket (9) is connected to the lead screw (11) are perpendicular to each other, and the connection between the moving bracket (9) and the screw (11) is provided with threads, and the upper end of the moving bracket (9) is provided with a bump and a vernier (10). The block is snapped into the groove below the main ruler (12) and can slide along the groove, the vernier (10) can slide along the upper surface of the main ruler (12), and the lower end of the mobile bracket (9) Ultrasonic receiving head (8) is installed, and described ultrasonic receiving head (8) and described ultrasonic transmitting head (3) face to install on the same horizontal line; The incremental encoder (4) is fixed on the left fixed plate (7), the second gear (6) is coaxially fixed with one end of the lead screw (11), and the first gear (5 ) meshes with the second gear (6), and the first gear (5) is fixed on the shaft of the incremental encoder (4); The handle (14) is fixedly connected to the auxiliary ruler (13), and the auxiliary ruler (13) is fixedly connected to the other end of the lead screw (11); The control processing circuit is located inside the chassis (16). On the one hand, the control processing circuit drives the ultrasonic transmitting head (3) to emit ultrasonic waves, and on the other hand processes the ultrasonic signals received by the ultrasonic receiving head (8) to calculate the ultrasonic wave The speed of propagation, and information transmission between peripheral devices. 2. a kind of intelligent sound velocity measurement experimental device according to claim 1, is characterized in that, described control processing circuit comprises microprocessor, power amplifier, band-pass filter, automatic gain controller, amplifier, waveform shaping circuit, Phase difference comparison circuit and filter capacitor; the bandpass filter, the automatic gain controller, the amplifier, the waveform shaping circuit, the phase difference comparison circuit, the filter capacitor, the microprocessor and the The power amplifiers are connected sequentially, the input end of the power amplifier is connected to an input end of the phase difference comparison circuit, an output end of the waveform shaping circuit is connected to the microprocessor, and the output of the power amplifier is connected to the ultrasonic wave The transmitting head (3), the ultrasonic receiving head (8) is connected to the band-pass filter; the output of the incremental encoder (4) is connected to the microprocessor. 3. A kind of intelligent sound velocity measurement experiment device according to claim 1, is characterized in that, described incremental encoder (4) is positioned at the outside of left side fixed plate (7), and described first gear (5) And said second gear (6) is positioned at the inner side of left fixed plate (7). 4. A kind of intelligent sound speed measurement experimental device according to claim 1, characterized in that, the handle (14) and the auxiliary ruler (13) are located outside the right side fixing plate (7). 5. A kind of intelligent sound velocity measurement experiment device according to claim 1, is characterized in that, described peripheral equipment is arranged on described chassis (16) casing, comprises pilot lamp (20), liquid crystal display (21) , power switch (15), button (19), signal output interface (2) and signal selection knob (1), power amplifier output interface (17), receiving signal input interface (18); described indicator light (20), The liquid crystal display screen (21), the signal selection knob (1) and the buttons (19) are all connected with the microprocessor. 6. A kind of intelligent sound velocity measurement experimental device according to claim 2, characterized in that, the control processing circuit also includes a temperature detection module, the output of the temperature detection module is connected to the microprocessor, and the temperature detection module The module is used to detect the ambient temperature in real time. 7. A kind of intelligent sound velocity measurement experiment device according to claim 2, is characterized in that, described microprocessor adopts STM32 single-chip microcomputer, and described band-pass filter comprises operational amplifier OP07 and peripheral circuit, and described automatic gain controller Including AD603 and peripheral circuits, the amplifier includes operational amplifier OP07 and peripheral circuits, the waveform shaping circuit includes LM393 and peripheral circuits, the phase difference comparison circuit includes XOR gate 74LS86; the temperature detection module includes DS18B20. 8. A kind of intelligent sound velocity measurement experiment device according to claim 1, is characterized in that, described leading screw (11) two ends are respectively connected with described fixed plate (7) by bearing; Described handle (14) is passed The screw thread is fixedly connected with the said auxiliary scale (13). 9. according to the sound velocity measurement method of the intelligent sound velocity measurement experimental device described in any one of claim 1-8, it is characterized in that, comprises the steps: Step 1: Calibrate the electronic scale after the device is initialized, so that the vernier is at the zero scale line of the main scale; Step 2: the control processing circuit outputs a square wave signal s1 with a frequency of f, and the square wave signal drives the ultrasonic transmitter through a power amplifier to transmit ultrasonic waves with a frequency of f; Step 3: The control processing circuit converts the ultrasonic signal received by the ultrasonic receiving head into an electrical signal in real time, and processes it into a square wave signal s3; Step 4: Judge the phase difference between the square wave signal s1 and the square wave signal s3, if the phase difference is 0, record the coordinates of the ultrasonic receiving head; Step 5: Shake the handle to make the ultrasonic receiving head move to the right, and when the phase difference between the square wave signal s1 and the square wave signal s3 is judged to be 0, record the coordinates of the ultrasonic receiving head; Step 6: Repeat step 5 to record n+1 coordinates; Step 7: The difference between two adjacent coordinates among the n+1 coordinates recorded in step 6 is the wavelength λ of the ultrasonic wave, and the ultrasonic velocity value is calculated according to the formula υ=f·λ.