A free-field pressure wave sensor calibration device, control method and calibration method

Abstract

The present invention discloses a free-field pressure wave sensor calibration device, a control method and a calibration method. The free-field pressure wave sensor calibration device comprises a reference standard pressure wave generating device and a placement platform. The reference standard pressure wave generating device is installed on the placement platform. The placement platform has a calibration stand for placing a pressure wave sensor to be tested. The calibration stand can move laterally on the placement platform toward or away from the reference standard pressure wave generating device. The reference standard pressure wave generating device can generate a reference standard pressure wave. The free-field pressure wave sensor calibration device of the present invention is used to generate a reference standard pressure wave, so that the pressure wave sensor to be tested senses the reference standard pressure wave. The frequency difference between the sensing voltage signal output by the pressure wave sensor to be tested and the reference standard pressure wave is analyzed and determined as a frequency deviation calibration output value, which can be used to accurately calibrate the pressure wave sensor to be tested.

Description

Technical Field

[0001] The present invention relates to the field of pressure wave measurement device calibration, and in particular to a free-field pressure wave sensor calibration device, a control method and a calibration method. Background Art

[0002] In the process of acoustic research and application, it is often necessary to accurately measure sound waves through acoustic measurement equipment. Current acoustic measurement equipment is equipped with a microphone (acoustic-electric converter) that converts sound pressure signals into electrical signals.

[0003] Among the commonly used acoustic measurement equipment, the commonly used equipment is the pressure wave sensor. The pressure wave sensor is a device or apparatus that can sense the pressure signal and convert the pressure signal into a usable output sensing voltage signal (alternating voltage signal) according to a certain rule. The pressure sensor is usually composed of a pressure sensitive element and a signal processing unit. The pressure wave sensor has a sound inlet structure, and the sound inlet structure has a sound inlet hole for the sound pressure to enter; at the same time, a capacitor plate and a signal acquisition circuit board are provided, and a sensitive film is provided between the sound inlet structure and the capacitor plate. A detection capacitor is formed between the capacitor plate and the sensitive film. The change in the distance between the capacitor plate and the sensitive film causes the change in capacitance. The signal acquisition circuit board is connected to the capacitor plate through a signal column, which is used to collect the sound pressure signal (capacitor signal) and convert the sound pressure signal (capacitor signal) into a voltage signal and then amplify it. The output of the post-stage signal processing is to further process the voltage signal collected and amplified by the signal acquisition circuit board and then output it, thereby completing the conversion of the sound pressure signal to the voltage signal, impedance transformation and noise elimination processing.

[0004] In addition, depending on the applicable pressure wave frequency, a low-frequency pressure wave sensor is often used. The low-frequency pressure wave sensor is a type of pressure wave sensor that is mainly used to sense low-frequency pressure waves (below 20 Hz).

[0005] In practical applications, in order to ensure that the sensing voltage signal converted and output by the pressure wave sensor has higher accuracy, the pressure wave sensor is usually calibrated from time to time so that the frequency of the sensing voltage signal (alternating voltage signal) it outputs is consistent with the pressure wave frequency of its sensing source, thereby achieving the purpose of accurate detection of the low-frequency pressure wave frequency.

[0006] However, the current process of calibrating pressure wave sensors or low-frequency pressure wave microphones often requires calibration inside a confined space. Since the confined space and the sound inlet of the pressure wave sensor form a resonant cavity, there will always be a resonance signal during the calibration process, making it difficult to perform more accurate testing and calibration of the pressure wave sensor to be tested.

[0007] In addition, during the current domestic testing of free-field microphones, there is no standard placement position for pressure wave sensors. Differences in the positions of pressure wave sensors will have a significant impact on frequency response testing, making it impossible to reduce the impact of other uncertain factors when testing different batches of pressure wave sensors, resulting in large test errors. Summary of the invention

[0008] The object of the present invention is to provide a free-field pressure wave sensor calibration device to solve the technical problem that it is difficult to accurately calibrate the performance of the pressure wave sensor in sensing low-frequency pressure waves.

[0009] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0010] A free-field pressure wave sensor calibration device, used for calibrating a pressure wave sensor to be tested, comprises a reference standard pressure wave generating device 1 and a placement platform 2, wherein the reference standard pressure wave generating device 1 is installed on the placement platform 2, and the placement platform 2 has a calibration stand 4 for placing the pressure wave sensor to be tested, and the calibration stand 4 can move laterally on the placement platform 2 toward or away from the reference standard pressure wave generating device 1, and the reference standard pressure wave generating device 1 can generate a reference standard pressure wave ... The device 1 includes a cavity 5, a coil 6, an armature 7 and an eardrum 8. The cavity 5 is provided with a pressure wave generating port 10. The eardrum 8 is attached to the side of the cavity 5 where the pressure wave generating port 10 is provided, thereby closing the pressure wave generating port 10. One end of the armature 7 is fixedly connected to the center position of the eardrum 8 facing the inside of the cavity 5. The coil 6 is wrapped around the outer peripheral side of the armature 7 away from the eardrum 8, and the coil 6 is electrically connected to an external drive circuit capable of supplying alternating current, so that alternating current can be passed through the coil 6 through the external drive circuit.

[0011] The pressure wave sensor to be tested is placed on the calibration platform, and the placement platform 2 is used to place the pressure wave sensor to be tested to fix the relative position of the pressure wave sensor to be tested to the calibration sound source, thereby reducing the test error of different batches of sensors; then the free-field pressure wave sensor calibration device is started, and an alternating current is passed through the coil 6 using an external drive circuit. When there is an alternating current in the coil 6, a magnetic field with a pole change can be generated inside the area enclosed by the coil 6, thereby driving the armature 7 to vibrate up and down, and then driving the eardrum 8 to vibrate to generate a sinusoidal sound wave, thereby generating a reference standard pressure wave. According to the frequency and current intensity of the alternating current generated inside the coil 6, the direction and amplitude of the displacement of the armature 7 can be controlled , thereby controlling the frequency and amplitude of the generated pressure wave; the pressure wave sensor to be tested is located in the free field, and after sensing the reference standard pressure wave generated by the free field pressure wave sensor calibration device, a sensing voltage signal will be output. Therefore, by analyzing the frequency difference between the sensing voltage signal output by the pressure wave sensor to be tested and the reference standard pressure wave, the frequency deviation calibration output value of the pressure wave sensor to be tested is used as the tester, and the tester can calibrate the pressure wave sensor to be tested according to the frequency deviation calibration output value; and, since the pressure wave sensor to be tested is located in the free field, no resonant wave will be generated in the cavity 5, thereby avoiding a large measurement error of the pressure wave sensor to be tested, which can help improve the calibration accuracy.

[0012] Preferably, a guide rail 11 is fixed on the placement platform 2 , and the guide rail 11 is used for adjusting the position of the placement platform 2 . The calibration stand 4 is installed on the guide rail 11 , and the calibration stand 4 can be laterally displaced along the guide rail 11 .

[0013] The guide rail 11 enables the phase position between the pressure wave sensor to be tested and the free-field pressure wave sensor calibration device to be adjusted, thereby avoiding the position error between the pressure wave sensor to be tested and the standard sound source during the test process, thereby helping to improve the measurement accuracy after calibration.

[0014] Preferably, a laser source 12 is also fixed on the placement platform 2 , and the direction of the light beam emitted by the laser source 12 is aligned with the center position of the eardrum 8 .

[0015] The laser source 12 is used to correct the center line of the sound inlet of the pressure wave sensor to be tested to coincide with the center line of the eardrum 8. Specifically, by adjusting the height of the placement platform 2, the pressure wave sensors to be tested of different sizes can be aligned with the center position of the laser.

[0016] Open the sound inlet of the pressure wave sensor to be tested, adjust the height of the calibration platform 4 so that the center position of the sound inlet of the pressure wave sensor to be tested is aligned with the laser, and then adjust the horizontal distance of the calibration platform so that the relative position between the pressure wave sensor to be tested and the reference standard pressure wave generating device 1 is fixed.

[0017] Preferably, the free-field pressure wave sensor calibration device also includes a control device 3 and an external drive circuit 13; the external drive circuit 13 is electrically connected to the coil 6, and is used to supply alternating current to the coil 6; the control device 3 is electrically connected to the external drive circuit 13, and has a sensing voltage signal acquisition end for being electrically connected to the sensing voltage output end of the pressure wave sensor to be tested, and is used to output a sinusoidal wave signal to control the frequency and amplitude of the alternating current supplied to the coil 6 by the external drive circuit 13, and to collect the sensing voltage signal output by the pressure wave sensor to be tested, and to analyze and determine the frequency difference between the sensing voltage signal output by the pressure wave sensor to be tested and the alternating current supplied by the external drive circuit 13, as the frequency deviation calibration output value of the pressure wave sensor to be tested.

[0018] The control device 3 includes an upper computer and a lower computer. The upper computer refers to a computer that can directly issue control commands, and various signal changes (hydraulic pressure, water level, temperature, etc.) are displayed on the screen; the lower computer is a computer that directly controls the equipment to obtain the equipment status; the command issued by the upper computer is first given to the lower computer, and the lower computer then interprets the command into a corresponding timing signal to directly control the corresponding equipment; the lower computer reads the equipment status data (generally analog quantity) from time to time, converts it into a digital signal and feeds it back to the upper computer.

[0019] The lower computer is an AD / DA collector, which is used to convert the standard sinusoidal wave digital signal generated by the upper computer into an analog signal for the input of a low-frequency power amplifier, and to convert the sensing voltage signal collected from the pressure wave sensor to be tested into a digital signal for the upper computer, so as to analyze and determine the frequency difference between the sensing voltage signal output by the pressure wave sensor to be tested and the alternating current supplied by the external drive circuit (13) to control the frequency deviation calibration output value of the pressure wave sensor to be tested.

[0020] Preferably, the external drive circuit 13 has a low-frequency power amplifier for amplifying the sinusoidal wave signal transmitted by the control device 3 and outputting it to the coil 6 to generate an alternating current.

[0021] The low-frequency power amplifier is used to amplify the sinusoidal wave signal generated by the DA to achieve high-power output, and then drive the eardrum 8 through the coil 6 to generate a standard low-frequency pressure wave signal, thereby achieving a wide-band sound wave output from low frequency to high frequency, enhancing the applicability of the free-field pressure wave sensor calibration device of the present application.

[0022] Preferably, a sound-absorbing material layer 9 is attached to the inner wall surface of the cavity 5 except the eardrum 8 .

[0023] The influence of internal sound wave reflection on the vibration of the eardrum 8 can be reduced, thereby avoiding affecting the distortion of the waveform of the sound wave signal emitted by the eardrum 8.

[0024] Preferably, a grating ruler is also installed on the placement platform 2, and the grating ruler faces the direction of the calibration bracket.

[0025] The grating ruler is used to provide position information feedback of the calibration bracket, and the positioning accuracy can reach above 0.1 mm.

[0026] Preferably, a distance sensor installation position is provided above the placement platform 2 .

[0027] The distance sensor installation position is used to install the distance sensor to ensure the consistency of the test positions of different pressure wave sensors to be tested.

[0028] The present invention also discloses a free-field low-frequency pressure wave calibration method, which utilizes the free-field pressure wave sensor calibration device as described above. Specifically, the pressure wave sensor to be tested is mounted on the calibration stand 4 of the free-field pressure wave sensor calibration device, the free-field pressure wave sensor calibration device is started to generate a reference standard pressure wave, the pressure wave sensor to be tested is located in the free field, the reference standard pressure wave generated by the free-field pressure wave sensor calibration device is sensed, and the frequency difference between the sensing voltage signal output by the pressure wave sensor to be tested and the reference standard pressure wave is analyzed and determined as the frequency deviation calibration output value of the pressure wave sensor to be tested, so as to calibrate the pressure wave sensor to be tested.

[0029] The free-field low-frequency pressure wave calibration method can be implemented in a free field without the need to calibrate the pressure wave sensor to be tested in a closed space, and can achieve wide-band sound wave output from low frequency to high frequency. Especially for low-frequency pressure wave sensors, it can increase the output amplitude value of low-frequency sound waves and realize frequency deviation testing and calibration processing of a lower lower limit measurement frequency in the free field.

[0030] The present invention also discloses a control method for a free-field pressure wave sensor calibration device, using the free-field pressure wave sensor calibration device as described above, comprising the following steps:

[0031] S1, the control device 3 outputs a sine wave signal to the external drive circuit 13;

[0032] S2, the sine wave signal is amplified by the low-frequency power amplifier in the external drive circuit 13 and then output to the coil 6, and an alternating current is generated in the coil 6;

[0033] S3, the alternating current generated in the coil 6 drives the armature 7 to vibrate up and down;

[0034] S4, as the armature 7 vibrates up and down, the eardrum 8 is driven to reciprocate, thereby generating a reference standard pressure wave;

[0035] S5, installing the pressure wave sensor to be tested on the calibration stand 4, opening the sound inlet of the pressure wave sensor to be tested and aligning the center position of the sound inlet of the pressure wave sensor to be tested with the laser;

[0036] S6. Adjust the lateral displacement of the calibration platform so that the distance between the pressure wave sensor to be tested and the free-field pressure wave sensor calibration device is relatively fixed;

[0037] S7. The pressure wave sensor to be tested senses the reference standard pressure wave, and the control device 3 collects the sensing voltage signal output by the pressure wave sensor to be tested, and analyzes and determines the frequency difference between the sensing voltage signal output by the pressure wave sensor to be tested and the alternating current supplied by the external drive circuit 13 as the frequency deviation calibration output value of the pressure wave sensor to be tested.

[0038] The present invention has the following beneficial effects:

[0039] 1. The free-field pressure wave sensor calibration device disclosed in the present invention does not need to be calibrated in a closed space, and can achieve wide-band sound wave output from low frequency to high frequency; it solves the technical problem in the prior art that the cavity resonance frequency caused by the pressure wave sensor to be tested being located in a closed space, resulting in a large measurement error in the frequency response detection of the pressure wave sensor to be tested, thereby helping to improve the calibration accuracy; it can also increase the output amplitude value of the low-frequency sound wave to achieve a lower lower limit measurement frequency of the free field; because the phase position between the pressure wave sensor to be tested and the free-field pressure wave sensor calibration device can be adjusted, the position error between the pressure wave sensor to be tested and the standard sound source during the test process can be avoided, thereby helping to improve the measurement accuracy after calibration.

[0040] 2. The free-field pressure wave calibration method disclosed in the present invention can be implemented in a free field without the need to calibrate the pressure wave sensor to be tested in a closed space, and can achieve wide-band sound wave output from low frequency to high frequency. Especially for low-frequency pressure wave sensors, it can increase the output amplitude value of low-frequency sound waves and achieve a lower lower limit measurement frequency of the free field.

[0041] 3. The control method of the free-field pressure wave sensor calibration device disclosed in the present invention is simple to operate, and the test results can be intuitively seen on the control device end, and the test data can be automatically compared with the standard data, which can reduce the errors caused by manual operation and improve the accuracy and efficiency of calibration. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to make the purpose, technical solution and advantages of the invention more clear, the present invention will be further described in detail below with reference to the accompanying drawings, in which:

[0043] Figure 1It is a schematic structural diagram of the free-field pressure wave sensor calibration device of the present invention.

[0044] Figure 2 This is a schematic diagram of the external structure of the benchmark standard pressure wave generating device of the present invention.

[0045] Explanation of the accompanying symbols: 1. Reference standard pressure wave generating device; 2. Placing platform; 3. Control device; 4. Calibration stand; 5. Cavity; 6. Coil; 7. Armature; 8. Tympanic membrane; 9. Sound-absorbing material layer; 10. Pressure wave generating port; 11. Guide rail; 12. Laser source; 13. External drive circuit. DETAILED DESCRIPTION

[0046] To make the purpose, technical solution and advantages of the embodiments of the present invention more clear, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0047] It should be noted that similar numbers and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings. In the description of the present invention, it should be noted that the orientation or position relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. is based on the orientation or position relationship shown in the drawings, or the orientation or position relationship in which the invention product is usually placed when used, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance. In addition, the terms "horizontal", "vertical", etc. do not mean that the components are absolutely horizontal or suspended, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted. In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0048] The present invention solves the technical problem that since the pressure wave sensor to be tested is located in a closed space, resonance occurs in the detection cavity, causing large measurement errors in the response data of the pressure wave sensor to be tested during the detection process, thereby helping to improve the calibration accuracy.

[0049] like Figure 1 and Figure 2 As shown, based on the above technical problems to be solved, the present invention discloses a free-field pressure wave sensor calibration device, which is used to calibrate the pressure wave sensor to be tested, including a reference standard pressure wave generating device 1 and a placement platform 2, wherein the reference standard pressure wave generating device 1 is installed on the placement platform 2, and the placement platform 2 has a calibration stand 4 for placing the pressure wave sensor to be tested, and the calibration stand 4 can move laterally on the placement platform 2 toward or away from the reference standard pressure wave generating device 1, and the reference standard pressure wave generating device 1 can generate a reference standard pressure wave, The reference standard pressure wave generating device 1 includes a cavity 5, a coil 6, an armature 7 and an eardrum 8. The cavity 5 is provided with a pressure wave generating port 10. The eardrum 8 is attached to the side of the cavity 5 where the pressure wave generating port 10 is provided, thereby closing the pressure wave generating port 10. One end of the armature 7 is fixedly connected to the center position of the eardrum 8 facing the inside of the cavity 5. The coil 6 surrounds the outer peripheral side of the armature 7 away from the eardrum 8, and the coil 6 is electrically connected to an external drive circuit capable of supplying alternating current, so that alternating current can be passed through the coil 6 through the external drive circuit.

[0050] Specifically, the cavity 5 has a rectangular parallelepiped, a cube or a cylinder, preferably a cylinder.

[0051] Specifically, the eardrum 8 needs to be made of a material that is light in weight and has high hardness, such as carbon fiber material.

[0052] Specifically, in order to satisfy a larger dynamic range, the armature 7 adopts a long stroke design, and the stroke range is 0-8 mm.

[0053] The pressure wave sensor to be tested is placed on the calibration platform, and the placement platform 2 is used to place the pressure wave sensor to be tested to fix the relative position of the pressure wave sensor to be tested to the calibration sound source, thereby reducing the test error of different batches of sensors; then the free-field pressure wave sensor calibration device is started, and an alternating current is passed through the coil 6 using an external drive circuit. When there is an alternating current in the coil 6, a magnetic field with a pole change can be generated inside the area enclosed by the coil 6, thereby driving the armature 7 to vibrate up and down, and then driving the eardrum 8 to vibrate to generate a sinusoidal sound wave, thereby generating a reference standard pressure wave. According to the frequency and current intensity of the alternating current generated inside the coil 6, the direction and amplitude of the displacement of the armature 7 can be controlled , thereby controlling the frequency and amplitude of the generated pressure wave; the pressure wave sensor to be tested is located in the free field, and after sensing the reference standard pressure wave generated by the free field pressure wave sensor calibration device, a sensing voltage signal will be output. Therefore, by analyzing the frequency difference between the sensing voltage signal output by the pressure wave sensor to be tested and the reference standard pressure wave, the frequency deviation calibration output value of the pressure wave sensor to be tested is used as the tester, and the tester can calibrate the pressure wave sensor to be tested according to the frequency deviation calibration output value; and, since the pressure wave sensor to be tested is located in the free field, no resonant wave will be generated in the cavity 5, thereby avoiding a large measurement error of the pressure wave sensor to be tested, which can help improve the calibration accuracy.

[0054] As a further preferred embodiment of the benchmark standard pressure wave generating device 1, the inner wall surface of the cavity 5 except the eardrum 8 is affixed with a sound-absorbing material layer 9, which can reduce the impact of internal sound wave reflection on the vibration of the eardrum 8 and avoid affecting the distortion of the sound wave signal waveform emitted by the eardrum 8.

[0055] As a further preferred solution for the placement platform 2, a guide rail 11 is fixed on the placement platform 2, and the guide rail 11 is used to adjust the position of the placement platform 2. The calibration stand 4 has rollers adapted to the guide rail 11. The calibration stand 4 is installed on the guide rail 11. The calibration stand 4 can be laterally displaced along the guide rail 11. The length of the guide rail 11 can be customized according to demand, and is generally 1 to 5 meters long.

[0056] The guide rail 11 enables the phase position between the pressure wave sensor to be tested and the free-field pressure wave sensor calibration device to be adjusted, thereby avoiding the position error between the pressure wave sensor to be tested and the standard sound source during the test process, thereby helping to improve the measurement accuracy after calibration.

[0057] As a further preferred solution of the placement platform 2, a grating ruler is also installed on the placement platform 2, and the grating ruler faces the direction of the calibration bracket for feedback of the position information of the calibration bracket, and the positioning accuracy can reach more than 0.1 mm.

[0058] As a further preferred solution of the placement platform 2, a laser source 12 is also fixed on the placement platform 2, and the direction of the light beam emitted by the laser source 12 is aligned with the center position of the eardrum 8; the laser source 12 is used to correct the center line of the sound inlet of the pressure wave sensor to be tested to coincide with the center line of the eardrum 8. Specifically, by adjusting the height of the placement platform 2, the pressure wave sensors to be tested of different sizes can be aligned with the center position of the laser.

[0059] Open the sound inlet of the pressure wave sensor to be tested, adjust the height of the calibration platform 4 so that the center position of the sound inlet of the pressure wave sensor to be tested is aligned with the laser, and then adjust the horizontal distance of the calibration platform so that the relative position between the pressure wave sensor to be tested and the reference standard pressure wave generating device 1 is fixed.

[0060] As a further preferred solution of the placement platform 2, the placement platform 2 has a plurality of microporous structures, and the microporous structures are filled with a sound-absorbing material layer 9 to reduce the influence of plane sound wave reflection;

[0061] As an embodiment of the micropore, the micropore has a diameter of 3 mm and a length of 1 cm.

[0062] As a further preferred solution for placing the platform 2, a distance sensor installation position is provided above the placing platform 2 for installing the distance sensor to ensure the consistency of the test positions of different pressure wave sensors to be tested.

[0063] As a preferred solution of the free-field pressure wave sensor calibration device, it also includes a control device 3 and an external drive circuit 13; the external drive circuit 13 is electrically connected to the coil 6, and is used to supply alternating current to the coil 6; the control device 3 is electrically connected to the external drive circuit 13, and has a sensing voltage signal acquisition end for being electrically connected to the sensing voltage output end of the pressure wave sensor to be tested, and is used to output a sinusoidal wave signal to control the frequency and amplitude of the alternating current supplied to the coil 6 by the external drive circuit 13, and to collect the sensing voltage signal output by the pressure wave sensor to be tested, and to analyze and determine the frequency difference between the sensing voltage signal output by the pressure wave sensor to be tested and the alternating current supplied by the external drive circuit 13, as the frequency deviation calibration output value of the pressure wave sensor to be tested.

[0064] The control device 3 includes an upper computer and a lower computer. The upper computer refers to a computer that can directly issue control commands, and various signal changes (hydraulic pressure, water level, temperature, etc.) are displayed on the screen; the lower computer is a computer that directly controls the equipment to obtain the equipment status; the command issued by the upper computer is first given to the lower computer, and the lower computer then interprets the command into a corresponding timing signal to directly control the corresponding equipment; the lower computer reads the equipment status data (generally analog quantity) from time to time, converts it into a digital signal and feeds it back to the upper computer.

[0065] Specifically, the lower computer is an AD / DA collector, which is used to convert the standard sinusoidal wave digital signal generated by the upper computer into an analog signal for the input of a low-frequency power amplifier, and convert the sensing voltage signal collected from the pressure wave sensor to be tested into a digital signal for the upper computer, so as to analyze and determine the frequency difference between the sensing voltage signal output by the pressure wave sensor to be tested and the alternating current supplied by the external drive circuit (13) to control the frequency deviation calibration output value of the pressure wave sensor to be tested.

[0066] As a preferred solution of the control device 3, the external drive circuit 13 has a low-frequency power amplifier, which is used to amplify the sine wave signal transmitted by the control device 3 and output it to the coil 6 to generate an alternating current. The low-frequency power amplifier is used to amplify the sine wave signal generated by the DA to achieve high-power output, and then drive the eardrum 8 through the coil 6 to generate a standard low-frequency pressure wave signal, thereby achieving a wide-band sound wave output from low frequency to high frequency, and enhancing the applicability of the free-field pressure wave sensor calibration device of the present application.

[0067] Specifically, the free-field pressure wave sensor calibration device disclosed in the present application document can generate a reference standard pressure wave with a frequency range of 0.01 to 500 Hz, wherein the frequency range of the standard low-frequency pressure wave is 0.01 to 20 Hz.

[0068] The free-field pressure wave sensor calibration device disclosed in the present application document has the advantage of a large low-frequency response amplitude compared to existing similar devices, and can achieve a lower lower limit frequency during the free-field test process.

[0069] The free-field pressure wave sensor calibration device disclosed in the present application document can be used to test and calibrate pressure wave sensors and even low-frequency pressure wave sensors, and is also suitable for low-frequency testing and calibration of microphones.

[0070] The present invention also discloses a free-field low-frequency pressure wave calibration method, which utilizes the free-field pressure wave sensor calibration device as described above. Specifically, the pressure wave sensor to be tested is mounted on the calibration stand 4 of the free-field pressure wave sensor calibration device, the free-field pressure wave sensor calibration device is started to generate a reference standard pressure wave, the pressure wave sensor to be tested is located in the free field, the reference standard pressure wave generated by the free-field pressure wave sensor calibration device is sensed, and the frequency difference between the sensing voltage signal output by the pressure wave sensor to be tested and the reference standard pressure wave is analyzed and determined as the frequency deviation calibration output value of the pressure wave sensor to be tested, so as to calibrate the pressure wave sensor to be tested.

[0071] The free-field low-frequency pressure wave calibration method can be implemented in a free field without the need to calibrate the pressure wave sensor to be tested in a closed space, and can achieve wide-band sound wave output from low frequency to high frequency. Especially for low-frequency pressure wave sensors, it can increase the output amplitude value of low-frequency sound waves and realize frequency deviation testing and calibration processing of a lower lower limit measurement frequency in the free field.

[0072] In view of the technical solution of the free-field pressure wave sensor calibration device as described above, the present invention further discloses a control method of the free-field pressure wave sensor calibration device, comprising the following steps:

[0073] S1, the control device 3 outputs a sine wave signal to the external drive circuit 13;

[0074] S2, the sine wave signal is amplified by the low-frequency power amplifier in the external drive circuit 13 and then output to the coil 6, and an alternating current is generated in the coil 6;

[0075] S3, the alternating current generated in the coil 6 drives the armature 7 to vibrate up and down;

[0076] S4, as the armature 7 vibrates up and down, the eardrum 8 is driven to reciprocate, thereby generating a reference standard pressure wave;

[0077] S5, installing the pressure wave sensor to be tested on the calibration stand 4, opening the sound inlet of the pressure wave sensor to be tested and aligning the center position of the sound inlet of the pressure wave sensor to be tested with the laser;

[0078] S6. Adjust the lateral displacement of the calibration platform so that the distance between the pressure wave sensor to be tested and the free-field pressure wave sensor calibration device is relatively fixed;

[0079] S7. The pressure wave sensor to be tested senses the reference standard pressure wave, and the control device 3 collects the sensing voltage signal output by the pressure wave sensor to be tested, and analyzes and determines the frequency difference between the sensing voltage signal output by the pressure wave sensor to be tested and the alternating current supplied by the external drive circuit 13 as the frequency deviation calibration output value of the pressure wave sensor to be tested.

[0080] Specifically, the detection data refers to parameters such as the waveform and amplitude of the reference standard pressure wave sensed by the pressure wave sensor to be tested.

[0081] This control method is simple to operate, and the test results can be intuitively seen at the control device 3 end, and the test data can be automatically compared with the standard data, which can reduce the errors caused by manual operation and improve the accuracy and efficiency of calibration. Example

[0082] As an embodiment of the free-field pressure wave sensor calibration device disclosed in the present application document, it includes a reference standard pressure wave generating device 1, a placement platform 2 and a control device 3. The reference standard pressure wave generating device 1 is installed on the placement platform 2. The placement platform 2 has a calibration stand 4 for placing the pressure wave sensor to be tested. The reference standard pressure wave generating device 1 can generate a reference standard pressure wave.

[0083] In order to meet the requirement of having a higher sound pressure value at a lower frequency, the reference standard pressure wave generating device 1 includes a cavity 5, a coil 6, an armature 7 and an eardrum 8. The cavity 5 is a cylindrical structure with a diameter of 80 cm and a wall thickness of 0.5 cm. The inner wall surface of the cavity 5 except the eardrum 8 is affixed with a sound-absorbing material layer 9, which can reduce the influence of internal sound wave reflection on the vibration of the eardrum 8 and avoid affecting the distortion of the sound wave signal waveform emitted by the eardrum 8. The eardrum 8 is made of carbon fiber material and has good sealing performance.

[0084] In order to satisfy a larger dynamic range, the coil 6 and the armature 7 are designed with a long stroke. In this embodiment, the stroke of the armature is 5 mm.

[0085] In order to ensure that the waveform distortion is small, the resistance of coil 6 is designed to be about 4 ohms.

[0086] The cavity 5 is provided with a pressure wave generating port 10, and the eardrum 8 is attached to the side of the cavity 5 where the pressure wave generating port 10 is provided to seal the pressure wave generating port 10. The eardrum 8 needs to be made of a material with a light weight and a high hardness, such as a carbon fiber material; one end of the armature 7 is fixedly connected to the center position of the eardrum 8 facing the inside of the cavity 5, and the coil 6 is wrapped around the outer peripheral side of the armature 7 away from the eardrum 8, and the coil 6 is electrically connected to an external drive circuit that can supply alternating current, so that alternating current can be passed through the coil 6 through the external drive circuit.

[0087] A guide rail 11 is fixed on the placement platform 2, and the guide rail 11 is used to adjust the position of the placement platform 2. The calibration stand 4 has rollers adapted to the guide rail 11. The calibration stand 4 is installed on the guide rail 11. The calibration stand 4 can be laterally displaced along the guide rail 11. The length of the guide rail 11 can be customized according to needs, and is generally 1 to 5 meters long.

[0088] The placing platform 2 is also equipped with a grating ruler, which faces the direction of the calibration bracket and is used to provide position information feedback of the calibration bracket. The positioning accuracy can reach more than 0.1 mm.

[0089] A laser source 12 is also fixed on the placement platform 2, and the direction of the light beam emitted by the laser source 12 is aligned with the center position of the eardrum 8; the laser source 12 is used to correct the center line of the sound inlet of the pressure wave sensor to be tested to coincide with the center line of the eardrum 8. Specifically, by adjusting the height of the placement platform 2, the pressure wave sensors to be tested of different sizes can be aligned with the center position of the laser.

[0090] The placement platform 2 has a plurality of microporous structures, and the microporous structures are filled with a sound-absorbing material layer 9 to reduce the influence of plane sound wave reflection. The microporous structures have a diameter of 3 mm and a length of 1 cm.

[0091] A distance sensor installation position is provided above the placement platform 2 for installing a distance sensor to ensure consistency of the test positions of different pressure wave sensors to be tested.

[0092] The control device 3 includes a host computer, a slave computer and an external drive circuit 13. The control device 3 is used for analyzing the test signals of the pressure wave sensor to be tested and the standard sensor, and generating standard sinusoidal wave digital signals; the control device 3 includes a host computer and a slave computer. The host computer refers to a computer that can directly issue control commands, and various signal changes (hydraulic pressure, water level, temperature, etc.) are displayed on the screen; the slave computer is an AD / DA collector, which is used to convert the analog signals of the pressure wave sensor to be tested and the standard sensor into digital signals for computer analysis, and convert the standard sinusoidal wave digital signals generated by the host computer into analog signals for the input of the low-frequency power amplifier.

[0093] A low-frequency power amplifier is installed in the external driving circuit 13; the low-frequency power amplifier is used to amplify the sinusoidal wave signal generated by the DA to achieve high-power output, and drive the eardrum 8 to generate a sinusoidal wave signal through the coil 6, thereby achieving a wide-band sound wave output from low frequency to high frequency, thereby enhancing the applicability of the free-field pressure wave sensor calibration device of the present application.

[0094] The working principle of generating a reference standard pressure wave in this embodiment is as follows: a sinusoidal wave signal is outputted by the host computer as an input signal of a low-frequency external drive circuit 13, and is outputted to the coil 6 via a low-frequency power amplifier. The alternating current generated by the coil 6 drives the armature 7 connected to the eardrum 8 to vibrate up and down, thereby driving the eardrum 8 to generate a reciprocating motion following the input sinusoidal signal, thereby generating a reference standard pressure wave in a space environment.

[0095] The free-field pressure wave sensor calibration device, control method and calibration method disclosed in the present invention have the following technical effects:

[0096] 1. The free-field pressure wave sensor calibration device disclosed in the present invention does not need to be calibrated in a closed space, and can achieve wide-band sound wave output from low frequency to high frequency; it solves the technical problem in the prior art that the cavity resonance frequency caused by the pressure wave sensor to be tested being located in a closed space, resulting in a large measurement error in the frequency response detection of the pressure wave sensor to be tested, thereby helping to improve the calibration accuracy; it can also increase the output amplitude value of the low-frequency sound wave to achieve a lower lower limit measurement frequency of the free field; because the phase position between the pressure wave sensor to be tested and the free-field pressure wave sensor calibration device can be adjusted, the position error between the pressure wave sensor to be tested and the standard sound source during the test process can be avoided, thereby helping to improve the measurement accuracy after calibration.

[0097] 2. The free-field pressure wave calibration method disclosed in the present invention can be implemented in a free field without the need to calibrate the pressure wave sensor to be tested in a closed space, and can achieve wide-band sound wave output from low frequency to high frequency. Especially for low-frequency pressure wave sensors, it can increase the output amplitude value of low-frequency sound waves and achieve a lower lower limit measurement frequency of the free field.

[0098] 3. The control method of the free-field pressure wave sensor calibration device disclosed in the present invention is simple to operate, and the test results can be intuitively seen on the control device end, and the test data can be automatically compared with the standard data, which can reduce the errors caused by manual operation and improve the accuracy and efficiency of calibration.

[0099] It is understood that the present invention is described by some embodiments, and those skilled in the art are aware that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. Under the teachings of the present invention, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. The embodiments described in the present invention are part of the embodiments of the present invention, rather than all of the embodiments. The components of the embodiments of the present invention generally described and shown in the drawings herein may be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all other embodiments obtained by ordinary technicians in the art without creative work based on the embodiments in the present invention belong to the scope of protection of the present invention.

Claims

1. A free-field pressure wave sensor calibration device, characterized in that: The device is used for calibrating a pressure wave sensor to be tested, comprising a reference standard pressure wave generating device (1) and a placement platform (2), wherein the reference standard pressure wave generating device (1) is installed on the placement platform (2), and the placement platform (2) is provided with a calibration stand (4) for placing the pressure wave sensor to be tested, and the calibration stand (4) can move laterally on the placement platform (2) in a direction close to or away from the reference standard pressure wave generating device (1), and the reference standard pressure wave generating device (1) can generate a reference standard pressure wave, and the reference standard pressure wave generating device (1) comprises a cavity (5), a coil (6), an armature (7) and an eardrum (8), and the cavity (5) is provided with a pressure The eardrum (8) is attached to the side of the cavity (5) where the pressure wave generating opening (10) is opened, so as to close the pressure wave generating opening (10); one end of the armature (7) is fixedly connected to the center position of the eardrum (8) facing the inside of the cavity (5); the coil (6) surrounds the outer peripheral side of the armature (7) away from the eardrum (8), and the coil (6) is electrically connected to an external drive circuit capable of supplying alternating current, so that alternating current can be passed into the coil (6) through the external drive circuit; a laser source (12) is also fixed on the placement platform (2), and the direction of the light beam emitted by the laser source (12) is aligned with the center position of the eardrum (8).

2. The free-field pressure wave sensor calibration device according to claim 1, characterized in that: A guide rail (11) is fixed on the placement platform (2), and the guide rail (11) is used to adjust the position of the placement platform (2). The calibration platform (4) is installed on the guide rail (11), and the calibration platform (4) can be laterally displaced along the guide rail (11).

3. The free-field pressure wave sensor calibration device according to claim 2, characterized in that: The free-field pressure wave sensor calibration device also includes a control device (3) and an external drive circuit (13); The external drive circuit (13) is electrically connected to the coil (6) and is used to supply an alternating current to the coil (6); The control device (3) is electrically connected to the external drive circuit (13), and has a sensing voltage signal acquisition end electrically connected to the sensing voltage output end of the pressure wave sensor to be tested, and is used to output a sinusoidal wave signal to control the frequency and amplitude of the alternating current supplied by the external drive circuit (13) to the coil (6), and to collect the sensing voltage signal output by the pressure wave sensor to be tested, and to analyze and determine the frequency difference between the sensing voltage signal output by the pressure wave sensor to be tested and the alternating current supplied by the external drive circuit (13) as the frequency deviation calibration output value of the pressure wave sensor to be tested.

4. The free-field pressure wave sensor calibration device according to claim 3, characterized in that: The external drive circuit (13) has a low-frequency power amplifier for amplifying the sinusoidal wave signal transmitted by the control device (3) and outputting the amplified signal to the coil (6) to generate an alternating current.

5. The free-field pressure wave sensor calibration device according to claim 1, characterized in that: The inner wall surface of the cavity (5) except the eardrum (8) is affixed with a sound-absorbing material layer (9).

6. The free-field pressure wave sensor calibration device according to claim 1, characterized in that: A grating ruler is also installed on the placement platform (2), and the grating ruler faces the direction of the calibration bracket.

7. The free-field pressure wave sensor calibration device according to claim 1, characterized in that: A distance sensor installation position is arranged above the placement platform (2) for installing the distance sensor to ensure the consistency of the test positions of different pressure wave sensors to be tested.

8. A free-field low-frequency pressure wave calibration method, using the free-field pressure wave sensor calibration device according to any one of claims 1 to 4, characterized in that: The pressure wave sensor to be tested is mounted on a calibration stand (4) of the free-field pressure wave sensor calibration device, the free-field pressure wave sensor calibration device is started to generate a reference standard pressure wave, the pressure wave sensor to be tested is located in a free field, the reference standard pressure wave generated by the free-field pressure wave sensor calibration device is sensed, and the frequency difference between the sensing voltage signal output by the pressure wave sensor to be tested and the reference standard pressure wave is analyzed and determined as the frequency deviation calibration output value of the pressure wave sensor to be tested, so as to calibrate the pressure wave sensor to be tested.

9. A control method for a free-field pressure wave sensor calibration device, characterized in that: The free-field pressure wave sensor calibration device as claimed in claim 4 comprises the following steps: S1, the control device (3) outputs a sine wave signal to an external drive circuit (13); S2, the sine wave signal is amplified by a low-frequency power amplifier in an external drive circuit (13) and then output to the coil (6), thereby generating an alternating current in the coil (6); S3, the alternating current generated in the coil (6) drives the armature (7) to vibrate up and down; S4, as the armature (7) vibrates up and down, the eardrum (8) is driven to reciprocate, thereby generating a reference standard pressure wave; S5, installing the pressure wave sensor to be tested on the calibration stand (4), opening the sound inlet of the pressure wave sensor to be tested and aligning the center position of the sound inlet of the pressure wave sensor to be tested with the laser; S6. Adjust the lateral displacement of the calibration platform so that the distance between the pressure wave sensor to be tested and the free-field pressure wave sensor calibration device is relatively fixed; S7, the pressure wave sensor to be tested senses the reference standard pressure wave, and the control device (3) collects the sensing voltage signal output by the pressure wave sensor to be tested, and analyzes and determines the frequency difference between the sensing voltage signal output by the pressure wave sensor to be tested and the alternating current supplied by the control external drive circuit (13), as the frequency deviation calibration output value of the pressure wave sensor to be tested.

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