Calibrator for high-sound-pressure broadband noise sensor

Abstract

The invention relates to the technical field of acoustics, in particular to a high-sound-pressure broadband noise sensor calibrator which comprises a controller, a signal conditioning module, a signal amplification module, a power amplification module, a high-sound-pressure loudspeaker module and a signal conversion circuit which are in closed-loop sequential electric signal connection. The high-sound-pressure loudspeaker module comprises a high-sound-pressure loudspeaker, a sound pressure amplification tube fixing device, a sound pressure amplification tube, a plane wave generating tube, a microphone pre-tightening device and a microphone, and the sound pressure amplification tube fixing device is fixed to a horn mouth of the high-sound-pressure loudspeaker through a bolt; the sound pressure amplifying tube is installed on the sound pressure amplifying tube fixing device and located in the center of the outer side of a horn mouth of the high-sound-pressure loudspeaker, the high-sound-pressure loudspeaker is connected with the plane wave generating tube through threads, and the microphone is connected with the plane wave generating tube. The microphone pre-tightening device fixes the plane wave generating tube and the microphone together.

Description

Technical Field

[0001] The invention relates to the field of acoustic technology, in particular to a broadband multifunctional high sound pressure microphone calibrator. Background Art

[0002] In some areas of aerospace, high-voltage noise of more than 140dB will be generated. This noise will cause great damage to the human body or the interior of some precision instruments. In order to protect the normal operation of the equipment, high-sound pressure noise sensors are usually used to monitor it. When the sound pressure is greater than 140dB, the corresponding alarm mechanism will be triggered. In order to ensure the accuracy of the data, the frequency response, sensitivity and linearity of the sensor need to be calibrated. At present, the main popular calibration methods at home and abroad are electrostatic excitation method, piston sounding method and standing wave tube method.

[0003] However, in the past, there were relatively few cases involving noise measurements above 140dB, and the frequency range was relatively narrow, so wide-band calibration was not required. Therefore, common calibrators on the market can only calibrate the frequency domain response of the sensor when the sound pressure is lower than 140dB, or output high sound pressure values ​​at a single frequency of 250Hz, 500Hz, and 1000Hz. Against the background of the growing demand for high-sound-pressure microphone calibration, it is impossible to complete the measurement of frequency response under high sound pressure conditions, and cannot meet the requirements of high sound pressure and wide-band coverage.

[0004] With the development of the aerospace industry, there is a need to more accurately detect the noise generated by spacecraft. Therefore, it is necessary to design a high sound pressure wide-band noise sensor calibrator that can simultaneously meet the requirements of frequency response and linearity calibration of high sound pressure noise sensors. Summary of the invention

[0005] The purpose of the present invention is to provide a high sound pressure wideband noise sensor calibrator to solve the problem that the existing calibrator mentioned in the above background technology can only realize single-frequency high sound pressure (greater than 140dB) calibration or multi-frequency low sound pressure (less than 140dB). The function of calibrating the amplitude-frequency characteristics and sensitivity characteristics of the high sound pressure microphone at the same time is realized, and the self-calibration function of the high sound pressure calibrator is realized.

[0006] The technical solution adopted by the present invention is: a high sound pressure wide-band noise sensor calibrator, comprising a controller 1 connected by closed-loop sequential electrical signals, a signal conditioning module 2, a signal amplification module 3 (programmable amplification module), a power amplification module 4, a high sound pressure speaker module (sound pressure amplification module), and a signal conversion circuit 11 (data acquisition module), wherein the controller 1 is electrically connected to a host computer 12, and the high sound pressure speaker module comprises a high sound pressure speaker 5, a sound pressure amplification tube fixing device 6, a sound pressure amplification tube 7, a plane wave generating tube 8, a microphone pre-tightening device 9, and a microphone 10, wherein the sound pressure amplification tube fixing device 6 is fixed to the bell mouth of the high sound pressure speaker 5 by bolts, the sound pressure amplification tube 7 is installed on the sound pressure amplification tube fixing device 6 and is located at the center of the outer side of the bell mouth of the high sound pressure speaker 5, the high sound pressure speaker 5 is connected to the plane wave generating tube 8 by threads, the microphone 10 is connected to the plane wave generating tube 8, and the microphone pre-tightening device 9 fixes the plane wave generating tube 8 and the microphone 10 together.

[0007] The microphone 10 is electrically connected to a signal conversion circuit 11 , and the power amplifier module 4 is electrically connected to a high sound pressure speaker 5 .

[0008] The sound pressure amplifying tube 7 is a trumpet-shaped aluminum conical tube with a lower diameter of 30 mm, an upper diameter of 6 mm, a height of 18 mm, and a curvature coefficient of 1.

[0009] The plane wave generating tube 8 is an aluminum hollow tube with a length of 10 mm and a diameter of 3 mm.

[0010] During operation, the sweep frequency calibration function and fixed point calibration function of the calibrator are selected through the host computer 12, and then the corresponding sine wave signal (simulated sine wave signal) is generated by the controller 1. The sine wave signal is filtered through the signal conditioning module 2, and then the current is amplified by the signal amplification module 3 (the amplification factor is 2 times, 1 times, 1 / 2 times and 1 / 4 times), and finally the power is amplified by the power amplification module 4. The amplification factor of the power amplification module is fixed at 32 times. The total amplification factor from the controller 1 to the power amplification module 4 is the amplification factor of the signal amplification module 3 multiplied by the amplification factor of the power amplification module 4. The power amplification circuit is used to drive the high sound pressure speaker module to emit sound.

[0011] The high sound pressure speaker module includes a high sound pressure speaker 5, a sound pressure amplifier tube fixing device 6, a sound pressure amplifier tube 7, a plane wave generating tube 8, a microphone pre-tightening device 9, and a microphone 10. The high sound pressure speaker 5 is a sound generating device of the high sound pressure speaker module. The sound emitted by the high sound pressure speaker 5 is used as a sound source. The sound pressure amplifier tube 7 uses the principle of slow cross-section sound focusing (the principle is that when the sound passes through the slow cross-section, the sound is focused on one point through reflection, refraction, and interference, thereby amplifying the sound intensity of the sound) to act on the plane wave generating tube 8 to generate a high sound pressure sound signal. The generated high sound pressure sound signal acts on the matched noise sensor to be tested (microphone 10) through the plane wave generating tube 8.

[0012] The signal conversion circuit 11 is connected to the microphone 10 via a wire, and conditions the electrical signal generated by the microphone 10 to convert the AC signal into a corresponding RMS DC signal, which is then fed back to the host computer 12 via the controller 1 .

[0013] Finally, the host computer 12 plots the amplitude-frequency curve and sensitivity curve of the RMS DC signal to complete the calibration of the microphone 10. If the calibration result (as can be seen from the amplitude-frequency curve and sensitivity curve of the RMS DC signal) does not meet the requirements, the sine wave signal generated by the controller 1 is adjusted to recalibrate.

[0014] When the calibrator is self-calibrated, the microphone is replaced with a microphone that meets national standards and can be used for calibration. The connection method and working process are the same as those of the calibration work described above. The difference is that after the electrical signal generated by the microphone 10 passes through the signal conversion circuit 11, the output voltage of the calibrator is calibrated by the improved PID algorithm inside the controller. The flowchart of the algorithm is shown in the attached figure. Figure 3 As shown in the figure is the target voltage to be set, is the process variable, i.e. the effective value of the output electrical signal of the calibration sensor, and K is the proportional coefficient in the PID adjustment algorithm. The overall algorithm is implemented by the state machine. The principle is that when the output signal of the sound calibrator oscillates greatly, or When the situation is, the proportional function in the PID algorithm is controlled to reduce to achieve the purpose of eliminating oscillation. At the same time, the algorithm sets a three-level proportional parameter adjustment mechanism, which can change the proportional parameter at different frequencies, effectively improving the calibration efficiency without affecting the calibration accuracy.

[0015] Compared with the prior art, the beneficial effects of the present invention are: a sound pressure amplifier tube is provided, and a conical sound pressure amplifier tube is creatively used, which is the first invention of the present invention, and is characterized by a hollow conical tube, and the cross-sectional view is as follows: Figure 2As shown, the principle is to use the principle of acoustic focusing to amplify the sinusoidal sound pressure signal generated by the speaker. Compared with the traditional standing wave amplification method, this method can focus the sound pressure energy and generate high sound pressure signals in a wider frequency band. A plane wave sound tube is provided, which is a prior art. Its characteristic is that it is a hollow pipe. There is a relevant size calculation formula. According to the conditions for obtaining plane waves in cylindrical sound waveguide tubes and standards ISO 10534-2:1988(E) and GB / T 18696.2-2002, the working upper limit f of a circular tube with a diameter of d(m) must meet the following requirements:

[0016] In the formula is the speed of sound in air, The upper limit of the operating frequency of the plane wave generating tube After calculation, when the upper frequency is 8K, the diameter of the tube is 24.65mm. Considering that the diameter of the speaker is 30mm, the diameter of the cone tube should be 30mm. The amplified sound pressure signal is conditioned using the principle of pipeline acoustics to generate a plane wave that is more conducive to acoustic calibration and measurement. A host computer is set up to draw the amplitude-frequency characteristics and sensitivity characteristics of the microphone and issue commands to the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 It is an overall schematic diagram of the present invention; Figure 2 It is a partial diagram of the sound pressure amplification part; Figure 3 is the adaptive calibration algorithm flow chart; Figure 4 is a schematic top view of the present invention; Among them: 1-controller, 2-signal conditioning module, 3-signal amplification module, 4-power amplification module, 5-high sound pressure speaker module, 6-sound pressure amplification tube fixing device, 7-sound pressure amplification tube, 8-plane wave generating tube, 9-microphone pre-tightening device, 10-microphone, 11-signal conversion circuit, 12-host computer. DETAILED DESCRIPTION

[0019] The core of the present invention is to provide a high sound pressure wide-band noise sensor calibrator, which can realize the functions of simultaneously calibrating the amplitude-frequency characteristic and sensitivity of a high sound pressure microphone.

[0020] In order to enable those skilled in the art to better understand the scheme of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0021] See also Figure 1-4 A high sound pressure wide-band noise sensor calibrator includes a controller 1 connected by closed-loop sequential electrical signals, a signal conditioning module 2, a signal amplification module 3, a power amplification module 4, a high sound pressure speaker module, and a signal conversion circuit 11. In this embodiment, the signal conditioning module 2 adopts an existing signal conditioning (filtering) circuit. In this embodiment, the signal amplification module 3 is used to amplify the current signal, and an existing current signal amplification circuit can also be used. In this embodiment, the power amplification module 4 can use an existing power circuit. In this embodiment, the signal conversion circuit 11 conditions the electrical signal generated by the microphone 10 to convert the AC electrical signal into a corresponding RMS DC signal, and the existing signal conversion circuit 11 can be used.

[0022] The controller 1 is electrically connected to a host computer 12, and the high sound pressure speaker module includes a high sound pressure speaker 5, a sound pressure amplifying tube fixing device 6, a sound pressure amplifying tube 7, a plane wave generating tube 8, a microphone pre-tightening device 9, and a microphone 10. The sound pressure amplifying tube fixing device 6 is fixed to the bell mouth of the high sound pressure speaker 5 by bolts, and the sound pressure amplifying tube 7 is installed on the sound pressure amplifying tube fixing device 6 and is located at the center of the outer side of the bell mouth of the high sound pressure speaker 5. The high sound pressure speaker 5 is connected to the plane wave generating tube 8 by threads, and the microphone 10 is connected to the plane wave generating tube 8, and the microphone pre-tightening device 9 fixes the plane wave generating tube 8 and the microphone 10 together.

[0023] The microphone 10 is electrically connected to a signal conversion circuit 11 , and the power amplifier module 4 is electrically connected to a high sound pressure speaker 5 .

[0024] The sound pressure amplifying tube 7 is a trumpet-shaped aluminum conical tube with a lower diameter of 30 mm, an upper diameter of 6 mm, a height of 18 mm, and a curvature coefficient of 1.

[0025] The plane wave generating tube 8 is an aluminum hollow tube with a length of 10 mm and a diameter of 3 mm.

[0026] The sound pressure amplifier tube 7 is composed of a hollow aluminum conical tube with fixed curvature, fixed upper and lower diameters and heights obtained through a large number of simulations, calculations and experiments (its lower diameter is 30mm, upper diameter is 6mm, height is 18mm, and curvature coefficient is 1). The bottom and top openings are horn-shaped. Its function is to amplify the sound signal without distortion to make up for the deficiency of the sound pressure of the single speaker sound signal being lower than 145dB.

[0027] The plane wave generating tube 8 is composed of a fixed height internally smooth aluminum metal hollow tube (length 10 mm, diameter 3 mm) obtained through a large number of simulations, calculations and experiments, and the bottom opening can be in a trumpet shape. Its function is to generate plane waves that are more conducive to acoustic calibration.

[0028] The signal conversion circuit 11 is connected to the microphone 10 to be tested via a wire, and conditions the electrical signal generated by the sensor to convert the AC signal into a corresponding RMS DC signal.

[0029] Finally, the upper computer is used to draw the amplitude-frequency curve and sensitivity curve of the sensor to be tested, thereby completing the calibration of the microphone 10.

[0030] When the calibrator is self-calibrated, the microphone is replaced with a microphone that meets national standards and can be calibrated. The connection method and working process are the same as those of the calibration work. The difference is that after the electrical signal generated by the microphone 10 passes through the signal conversion circuit 11, it is calibrated by the improved PID algorithm inside the controller to calibrate the output voltage of the calibrator. The flowchart of the algorithm is shown in the attached figure. Figure 3 As shown in the figure is the target voltage to be set, is the process variable, i.e. the effective value of the output electrical signal of the calibration sensor, and K is the proportional coefficient in the PID adjustment algorithm. The overall algorithm is implemented by the state machine. The principle is that when the output signal of the sound calibrator oscillates greatly, or When the situation is, the proportional function in the PID algorithm is controlled to reduce to achieve the purpose of eliminating oscillation. At the same time, the algorithm sets a three-level proportional parameter adjustment mechanism, which can change the proportional parameter at different frequencies, effectively improving the calibration efficiency without affecting the calibration accuracy.

[0031] Based on the above embodiment, this embodiment uses a wide-band multifunctional high sound pressure microphone calibrator system to generate 130dB, 134dB, 144dB, 148dB, 154dB, 158dB sinusoidal noise in the range of 100Hz~10KHz during frequency sweeping, and can generate up to 168dB sound pressure at the frequency points of 1000Hz and 2000Hz during fixed-point calibration. The sweep frequency calibration function and the fixed-point calibration function can be selected through the host computer software to select the sound pressure level to be calibrated.

[0032] When sweeping the frequency, the frequency of the sine wave corresponds to the frequency of the sound source. When the sine wave is 1KHz, the sound source is 1KHz, and the sweep frequency range is 100Hz~10KHz. The sweep frequency step is 100Hz, which is written into the embodiment. Each frequency point corresponds to a sine wave amplitude, ensuring the in-band unevenness of the calibrator within the entire frequency band.

[0033] The above is a detailed introduction to the system of adjustable high-pressure sound source provided by the present invention. Specific examples are used in this article to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A high sound pressure broadband noise sensor calibrator, characterized in that: The invention comprises a controller (1), a signal conditioning module (2), a signal amplification module (3), a power amplification module (4), a high sound pressure speaker module, and a signal conversion circuit (11) connected in a closed-loop sequential electrical signal manner. The controller (1) is electrically connected to a host computer (12). The high sound pressure speaker module comprises a high sound pressure speaker (5), a sound pressure amplification tube fixing device (6), a sound pressure amplification tube (7), a plane wave generating tube (8), a microphone pre-tightening device (9), and a microphone (10). The sound pressure amplification tube fixing device (6) is fixed to the bell mouth of the high sound pressure speaker (5) by bolts. The sound pressure amplification tube (7) is mounted on the sound pressure amplification tube fixing device (6) and is located at the center of the outer side of the bell mouth of the high sound pressure speaker (5). The high sound pressure speaker (5) is connected to the plane wave generating tube (8) by threads. The microphone (10) is connected to the plane wave generating tube (8). The microphone pre-tightening device (9) fixes the plane wave generating tube (8) and the microphone (10) together.

2. A high sound pressure wideband noise sensor calibrator according to claim 1, characterized in that: The electrical signal of the microphone (10) is connected to a signal conversion circuit (11), and the electrical signal of the power amplification module (4) is connected to a high sound pressure speaker (5).

3. The high sound pressure broadband noise sensor calibrator according to claim 1, characterized in that: The sound pressure amplifying tube (7) is a trumpet-shaped aluminum conical tube with a lower diameter of 30 mm, an upper diameter of 6 mm, a height of 18 mm, and a curvature coefficient of 1.

4. The high sound pressure broadband noise sensor calibrator according to claim 1, characterized in that: The plane wave generating tube (8) is an aluminum hollow tube with a length of 10 mm and a diameter of 3 mm.

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