An automatic calibration system and calibration method for anechoic chamber testing

Abstract

The invention belongs to the technical field of instrument calibration, and discloses an automatic calibration system for anechoic chamber detection, which is applied to a semi-anechoic chamber or a full-anechoic chamber. A microphone is arranged on a trolley through an adjustment mechanism, and the trolley is connected to a traction detection mechanism. The traction detection mechanism adopts a pulley structure, which is used to drive the trolley and the microphone thereon to move along a steel cable, and detect the moving distance of the microphone. The steel cable is arranged along the sound center of the sound source toward the top angle of the anechoic chamber, and the adjustment mechanism is used to adjust the microphone so that it is parallel to the steel cable and arranged toward the sound source. The system also includes a power amplifier connected to the sound source, and the power amplifier and the microphone are both connected to a multi-channel collector, and the multi-channel collector and the traction detection mechanism are both connected to a test computer through a wireless router. The test computer receives the detection data of the multi-channel collector and the traction detection mechanism, automatically completes the calibration of the anechoic chamber, and issues control instructions to the traction detection mechanism.

Description

Technical Field

[0001] The invention relates to the technical field of instrument verification, and in particular to an automatic calibration system and a calibration method for anechoic chamber detection. Background Art

[0002] At present, the main standards and specifications for anechoic chamber calibration are JJF 1147-2006 "Calibration Specification for Acoustic Characteristics of Anechoic Chambers and Semi-anechoic Chambers", GB / T 6882-2016 "Acoustics—Determination of Sound Power Levels and Sound Energy Levels of Noise Sources Using Sound Pressure—Precision Methods for Anechoic Rooms and Hemi-anechoic Rooms", and ISO 3745:2012 / AMD.1:2017 "Acoustics—Determination of Sound Power Levels and Sound Energy Levels of Noise Sources using Sound Pressure—Precision Methods for Anechoic Rooms and Hemi-anechoic Rooms". The calibration of cutoff frequency and free field radius is the main content of anechoic chamber calibration. According to the provisions of the standard specification, a non-directional sound source should be placed in the center of the ground of the semi-anechoic chamber or the center of the ground grid of the full anechoic chamber. The sound source input signal can be pink noise or pure tone. The microphone is required to move along the path from the sound center of the sound source to the top corner or the midpoint of the top line of the anechoic chamber. The measurement starts from 0.5m from the sound center of the sound source, and is measured every 10cm until it reaches the edge of the wall and ceiling of the anechoic chamber. The measurement data of each point collected is fitted and calculated according to the formula specified in the standard specification, and the cutoff frequency and free field radius of the anechoic chamber are determined by the calculation results. It is usually required to measure at least five paths. Since some large-sized anechoic chambers are very large, manual measurement is a huge workload, so how to achieve automatic measurement to improve measurement efficiency and measurement accuracy is the focus of the industry.

[0003] The main disadvantages of the existing solutions are as follows:

[0004] 1. A stepper motor is used to drive the rotating wheel to rotate. The microphone is pulled to move in the anechoic chamber by winding the fishing line around the rotating wheel. Because the fishing line wrapped around the rotating wheel will cause the actual diameter of the rotating wheel to change, the actual moving distance of the microphone driven by the rotation of the rotating wheel will increase. The larger the size of the anechoic chamber, the more the fishing line is wrapped around the rotating wheel, and the greater the error caused by the movement of the microphone.

[0005] 2. The existing theoretical free sound field calculation methods of anechoic chambers are all based on nonlinear function models, and r0≥r is not considered when calculating the optimal value. iIn this case, the calculation of Lp will be wrong. The free field theoretical sound pressure level fitting model designed by the existing standards and calibration methods will have a large near-end error and a small far-end error, which does not conform to the actual sound field distribution characteristics of the anechoic room. Summary of the invention

[0006] The present invention provides an automatic calibration system and calibration method for anechoic chamber detection, which solves the problems of large measurement error of microphone moving distance in the existing calibration system, large near-end error and small far-end error in calibration calculation, etc.

[0007] The present invention can be achieved through the following technical solutions:

[0008] An automatic calibration system for anechoic chamber detection is applied to a semi-anechoic chamber or a full-anechoic chamber, comprising a sound source and a microphone arranged inside the anechoic chamber, and a test computer arranged outside the anechoic chamber, wherein the microphone is arranged on a trolley through an adjustment mechanism, and the trolley is connected to a traction detection mechanism, wherein the traction detection mechanism adopts a pulley structure, and is used to drive the trolley and the microphone thereon to move along a steel cable, and detect the moving distance of the microphone, wherein the steel cable is arranged along the sound center of the sound source toward the top angle of the anechoic chamber, and the adjustment mechanism is used to adjust the microphone so that it is arranged parallel to the steel cable and toward the sound source,

[0009] It also includes a power amplifier connected to the sound source, the power amplifier and the microphone are connected to the multi-channel collector, the multi-channel collector and the traction detection mechanism are connected to the test computer through a wireless router, the test computer receives the detection data of the multi-channel collector and the traction detection mechanism, automatically completes the calibration of the anechoic chamber, and issues control instructions to the traction detection mechanism.

[0010] Furthermore, the traction detection mechanism includes a fixed pulley, which is fixedly arranged on a steel cable near the top angle position by a clamping mechanism, a fishing line is wound around the fixed pulley, one end of the fishing line is connected to the trolley, and the other end passes through a meter and is connected to a winder, the trolley is rotatably connected to the steel cable, the winder is connected to a motor, the clamping mechanism is used to fix the fixed pulley so that it is arranged vertically with the steel cable, the motor is used to drive the winder to rotate, thereby pulling the trolley along the steel cable through the fishing line, and the meter is used to measure the length of the passing fishing line.

[0011] Further, the trolley includes a first flat plate, and two first U-shaped plates are arranged at intervals on the top surface of the first flat plate, both of which are arranged in cooperation with a movable pulley through a bearing, and the movable pulley is matched with a steel cable, and is connected to a microphone through an adjustment mechanism on the bottom surface of the first flat plate.

[0012] The adjustment mechanism includes a sleeve, a screw passes through the first plate and is threadedly matched with one end of the sleeve, a connecting rod is arranged inside the other end of the sleeve, and the exposed end of the connecting rod is connected to the opening clamp through an angle adjustment mechanism, the opening clamp is used to fix the microphone, and the angle adjustment mechanism is used to adjust the angle of the opening clamp together with the microphone.

[0013] A magnet capable of attracting a plurality of counterweights is disposed at one end of the bottom surface of the first flat plate, and a positioning bolt connected to the fishing line is disposed at the other end. By adjusting the number of counterweights, the first flat plate is always parallel to the steel cable.

[0014] A through hole is provided on the side wall of the sleeve, and an adjusting bolt is provided inside the through hole. The two threads cooperate with each other, and the length of the connecting rod extending into the sleeve is adjusted by tightening or loosening the adjusting bolt, thereby adjusting the distance between the microphone and the first flat plate. Combined with the angle adjustment mechanism, the microphone is directed toward the sound source and is always arranged parallel to the first flat plate.

[0015] Furthermore, the positioning bolt is arranged at an end close to the fixed pulley, the magnet is arranged at an end away from the fixed pulley, a hook is arranged between the positioning bolt and the adjustment mechanism, the hook is connected to the first plate through a height adjustment mechanism, and is used to hang the data cable of the microphone, and the height adjustment mechanism is used to adjust the distance between the hook and the first plate to make it consistent with the distance between the microphone and the first plate.

[0016] Furthermore, the clamping mechanism includes a second flat plate, a groove for the steel cable is provided on the top surface of the second flat plate, a plurality of pressure plates are arranged at intervals on the groove, the steel cable is fixed inside the groove by the cooperation of bolts and nuts, and a second U-shaped piece is disposed on the bottom surface of the second flat plate, and the second U-shaped piece is also arranged in cooperation with the fixed pulley through a bearing.

[0017] Furthermore, the first flat plate and the second flat plate have the same thickness, the first U-shaped piece and the second U-shaped piece have the same overall structure, their bottoms are planar structures with the same thickness, and the fixed pulley and the movable pulley also have the same structure.

[0018] A calibration method based on the automatic calibration system for anechoic chamber detection described above comprises the following steps:

[0019] Step 1: Set the sound source on the ground of the semi-anechoic chamber or the center of the ground grid of the full anechoic chamber, fix one end of the steel cable next to the sound source through a fixing block, and pass the other end of the steel cable through the trolley, cooperate with the two movable pulleys on it, extend to the top corner of the anechoic chamber and fix it, and then fix the fixed pulley on the steel cable at the top corner position through a clamping mechanism;

[0020] Step 2: The fishing line on the winding device passes through the meter, around the fixed pulley, and is connected to the positioning bolt of the first flat plate in the trolley. With the help of the adjustment mechanism, the first flat plate and the microphone are parallel to the steel cable, and the microphone is set toward the sound source. Then, the height adjustment mechanism is used to make the positions of the hook and the microphone consistent, and the data cable of the microphone is hung on the hook, and then connected to the multi-channel collector together with the sound source;

[0021] Step 3: Transmit the detection data of the multi-channel collector and meter counter to the measurement computer through the wireless router to complete the automatic calibration.

[0022] Furthermore, the measurement data at a distance of 0.5m to 1.5m from the sound source were selected for fitting to obtain the theoretical sound pressure level curve of the free sound field inside the anechoic chamber. During the calculation process, if r0≥0.5 appeared, r0=0.4 was uniformly taken to calculate the deviation between the measured sound pressure level and the theoretical sound pressure level.

[0023] The beneficial technical effects of the present invention are:

[0024] Through special structural designs such as trolleys, adjustment mechanisms, supporting mechanisms, etc., the microphone can be automatically and accurately moved along a sound path of the sound source without anyone, and complete the corresponding data collection and post-processing, so that the calibration and detection work of the anechoic chamber can be carried out in accordance with JJF 1147, GB / T 6882 or ISO 3745, greatly improving work efficiency and measurement accuracy; with the help of a wireless router, the door of the anechoic chamber can be kept closed during the calibration process, so as not to affect the calibration. The whole operation process is simple, easy to operate, and has high work efficiency, which is easy to promote and use. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0026] Figure 2 It is a schematic diagram of the coordination structure of the trolley, the adjustment mechanism and the traction detection mechanism of the present invention;

[0027] Figure 3 It is a schematic diagram of the matching structure of the trolley and the adjustment mechanism of the present invention;

[0028] Among them, 1-sound source, 2-microphone, 3-trolley, 301-first plate, 302-movable pulley, 4-traction detection mechanism, 401-fixed pulley, 402-fishing line, 403-meter counter, 404-winder, 405-clamping mechanism, 5-steel cable, 6-angle adjustment mechanism, 7-opening clamp, 8-magnet, 9-positioning bolt, 10-adjusting bolt, 11-suspension mechanism. DETAILED DESCRIPTION

[0029] The specific implementation of the present invention is described in detail below with reference to the accompanying drawings and preferred embodiments.

[0030] like Figure 1-3 As shown, the present invention provides an automatic calibration system for anechoic chamber detection, which is applied to a semi-anechoic chamber or a full-anechoic chamber, and includes a sound source 1 and a microphone 2 arranged inside the anechoic chamber, and a test computer arranged outside the anechoic chamber. The microphone is arranged on a trolley 3 through an adjustment mechanism, and the trolley is connected to a traction detection mechanism 4. The traction detection mechanism 4 adopts a pulley structure, which is used to drive the trolley 3 and the microphone 2 thereon to move along a steel cable 5, and detect the moving distance of the microphone 2. The steel cable 5 is arranged along the sound center of the sound source 1 toward the top angle of the anechoic chamber. The adjustment mechanism is used to adjust the microphone 2 so that it is parallel to the steel cable 5 and arranged toward the sound source 1. It also includes a power amplifier connected to the sound source 1. The power amplifier and the microphone 2 are all connected to a multi-channel collector. The multi-channel collector and the traction detection mechanism are all connected to the test computer through a wireless router. The test computer receives the detection data of the multi-channel collector and the traction detection mechanism, automatically completes the calibration of the anechoic chamber, and issues control instructions to the traction detection mechanism. In this way, through the cooperation of the meter meter and the winder, the moving distance of the fishing line of the traction trolley can be directly calculated with the help of the meter meter, without the need to use the winding wheel of the winder itself for calculation, and the measurement result is more accurate. At the same time, since the steel cable is arranged along the sound center of the sound source toward the top angle of the anechoic chamber, the trolley and the microphone move along the steel cable. Therefore, with the help of the adjustment mechanism, the microphone can always be parallel to the steel cable and arranged toward the sound center of the sound source. According to the calibration specifications, the sound transmission conditions of each specified distance point on a straight line, that is, a straight line parallel to the steel cable, can be measured very accurately, and the sound pressure level calibration of each specified distance point can be completed, reducing the error in the measurement result caused by the skew of the microphone angle. In addition, a wireless router is added, and the test computer and the wireless router can be connected through a 1.5mm thick flat network cable or a wireless network, which can minimize the cables that need to pass through the anechoic chamber, thereby ensuring that the anechoic chamber can be calibrated with the door closed without reserving a threading hole, thereby expanding the application scope of the calibration system.

[0031] Specifically, the traction detection mechanism 4 includes a fixed pulley 401, which is fixedly arranged on the steel cable 5 near the top angle position through a clamping mechanism 405, and a fishing line 402 is wound on the fixed pulley 401, one end of the fishing line 402 is connected to the trolley 3, and the other end passes through a meter 403 and is connected to a wire winder 404, the trolley 3 is rotatably connected to the steel cable 5, and the wire winder 404 is connected to a motor, the clamping mechanism 405 is used to fix the fixed pulley 401 so that it is vertically arranged with the steel cable 5, the motor is used to drive the wire winder 404 to rotate, so as to pull the trolley 3 to move along the steel cable 5 through the fishing line 402, and the meter 403 is used to measure the length of the passing fishing line 402. In this way, the wire winder 404 only performs the winding function, and the measurement function is performed by the meter 403, and the moving distance measurement of the trolley 3, i.e., the microphone 2, is more accurate.

[0032] The trolley 3 includes a first flat plate 301, and two first U-shaped plates are arranged at intervals on the top surface of the first flat plate 301, and they are both arranged in cooperation with the movable pulley 302 through bearings. For example, through holes are arranged on the two side walls of the first U-shaped plate, and bearings are arranged inside the through holes, and the inner rings of the bearings are matched with the rotating shafts at both ends of the movable pulley 302 to achieve a rotational connection. The movable pulley 302 cooperates with the steel cable 5 and is connected to the microphone 2 through an adjustment mechanism on the bottom surface of the first flat plate 301. In this way, the trolley with a plate structure arranges the two movable pulleys 302 and the adjustment mechanism on the same straight line to facilitate the subsequent parallel and angle adjustment of the microphone 2, and the rotational connection between the movable pulley 302 and the steel cable 5 can reduce the friction between the two, ensuring smooth operation of the trolley.

[0033] The adjustment mechanism includes a sleeve, a screw passes through the first plate and is threadedly matched with one end of the sleeve, a connecting rod is arranged inside the other end of the sleeve, and the exposed end of the connecting rod is connected to the open clamp 7 through an angle adjustment mechanism 6, the open clamp 7 is used to fix the microphone 2, and the angle adjustment mechanism 6 is used to adjust the angle of the open clamp 7 together with the microphone 2. A magnet 8 capable of adsorbing a plurality of counterweights is arranged at one end of the bottom surface of the first plate 301, and a positioning bolt 9 connected to the fishing line 402 is arranged at the other end, which is the end close to the fixed pulley 401. Since we arrange the microphone 2 and a series of connecting components on the bottom surface of the first plate 301, the center of gravity of the trolley 3 is changed. Therefore, we adjust the center of gravity of the trolley 3 by adjusting the number of counterweights, so that the first plate 301 is always parallel to the steel cable 5, so as to provide a basis for the subsequent parallel adjustment of the microphone 2;

[0034] At the same time, since the specifications and structures of the anechoic chamber are unlikely to be the same, the inclination angle of the steel cable may not be consistent, and the setting position of the sound source may also be different. Therefore, we set a through hole on the side wall of the sleeve, and set an adjustment bolt 10 inside the through hole. The two are threaded together. By tightening or loosening the adjustment bolt 10, the length of the connecting rod extending into the sleeve is adjusted, thereby adjusting the distance between the microphone and the first flat plate. Combined with the angle adjustment mechanism, the microphone is directed toward the sound source and is always set parallel to the first flat plate. Since the fishing line directly pulls the first flat plate, the parallel setting between the first flat plate and the microphone and the steel cable can ensure that the moving directions of the two are consistent and always move along the above-mentioned sound path. The measurement data is more consistent with the actual transmission of the sound source, and the accuracy of the calibration result is improved.

[0035] Since the data cable of the microphone needs to be connected to the multi-channel collector, a traction force will be generated on the microphone during the movement, causing the angle of the microphone to tilt. Therefore, we set a suspension mechanism 11 between the positioning bolt and the adjustment mechanism. The suspension mechanism 11 includes a hook, which is connected to the first plate through a height adjustment mechanism. It is used to mount the data cable of the microphone 2 to generate a supporting force thereon to reduce the impact of the above-mentioned traction force on the microphone. The height adjustment mechanism is used to adjust the distance between the hook and the first plate 301 to make it consistent with the distance between the microphone 2 and the first plate 301, so as to better provide supporting force.

[0036] The clamping mechanism 405 includes a second flat plate, a top surface of which is provided with a groove for the steel cable, a plurality of pressure plates are arranged at intervals on the groove, the steel cable is fixed inside the groove with the help of the pressure plates through the cooperation of bolts and nuts, and a second U-shaped piece is disposed on the bottom surface of the second flat plate, the second U-shaped piece is also arranged in cooperation with the fixed pulley through a bearing, and the specific fixing method is similar to that of the first U-shaped piece.

[0037] In order to make the fishing line parallel to the steel cable, the first flat plate and the second flat plate have the same thickness, the first U-shaped piece and the second U-shaped piece have the same overall structure, their bottoms are planar structures with the same thickness, and the movable pulley and the fixed pulley also have the same structure.

[0038] The present invention also provides a calibration method based on the automatic calibration system for anechoic chamber detection described above, comprising the following steps:

[0039] Step 1: Set the sound source on the ground of the semi-anechoic chamber or the center of the ground grid of the full anechoic chamber, fix one end of the steel cable next to the sound source through a fixing block, and pass the other end of the steel cable through the trolley, cooperate with the two movable pulleys on it, extend to the top corner of the anechoic chamber and fix it, and then fix the fixed pulley on the steel cable at the top corner position through a clamping mechanism;

[0040] Step 2: The fishing line on the winding device passes through the meter, around the fixed pulley, and is connected to the positioning bolt of the first flat plate in the trolley. With the help of the adjustment mechanism, the first flat plate and the microphone are parallel to the steel cable, and the microphone is set toward the sound source. Then, the height adjustment mechanism is used to make the positions of the hook and the microphone consistent, and the data cable of the microphone is hung on the hook, and then connected to the multi-channel collector together with the sound source;

[0041] Step 3: Transmit the detection data of the multi-channel collector and meter counter to the measurement computer through the wireless communication module to complete the automatic calibration.

[0042] The specific calibration process can refer to standard specifications such as JJF 1147-2006. Considering the sound field distribution of the anechoic chamber, the deviation between the measured sound pressure level near the sound source and the theoretical sound pressure level should be smaller than that at the far end. Therefore, when performing the theoretical sound pressure level calculation and sound center correction, the near end deviation should be small first. The measurement data of 0.5m to 1.5m away from the sound source are selected for fitting to obtain the theoretical sound pressure level curve of the free sound field inside the anechoic chamber, thereby improving the error distribution and avoiding the situation where the near-end sound field deviation is much greater than the far end. From a physical point of view, during the calculation process, if r0≥0.5 appears, it means that the microphone has been corrected to the back of the sound source, which is obviously inconsistent with the actual situation. At this time, the sound pressure has a large deviation. R0=0.4 is uniformly taken to calculate the deviation between the measured sound pressure level and the theoretical sound pressure level, thereby improving the final calibration accuracy.

[0043] Although specific embodiments of the present invention are described above, those skilled in the art should understand that these are merely examples and that various changes or modifications may be made to these embodiments without departing from the principles and essence of the present invention. Therefore, the scope of protection of the present invention is limited by the appended claims.

Claims

1. An automatic calibration system for anechoic chamber testing, characterized in that: The invention is applied to a semi-anechoic chamber or a full-anechoic chamber, and comprises a sound source and a microphone arranged inside the anechoic chamber, and a test computer arranged outside the anechoic chamber. The microphone is arranged on a trolley through an adjustment mechanism, and the trolley is connected to a traction detection mechanism. The traction detection mechanism adopts a pulley structure, which is used to drive the trolley and the microphone thereon to move along a steel cable and detect the moving distance of the microphone. The steel cable is arranged along the sound center of the sound source toward the top angle of the anechoic chamber, and the adjustment mechanism is used to adjust the microphone so that it is arranged parallel to the steel cable and toward the sound source. It also includes a power amplifier connected to the sound source, the power amplifier and the microphone are connected to the multi-channel collector, the multi-channel collector and the traction detection mechanism are connected to the test computer through a wireless router, the test computer receives the detection data of the multi-channel collector and the traction detection mechanism, automatically completes the calibration of the anechoic chamber, and issues control instructions to the traction detection mechanism; The traction detection mechanism includes a fixed pulley, which is fixedly arranged on a steel cable near the top angle through a clamping mechanism, a fishing line is wound around the fixed pulley, one end of the fishing line is connected to a trolley, and the other end passes through a meter and is connected to a wire winder, the trolley is rotatably connected to the steel cable, the wire winder is connected to a motor, the clamping mechanism is used to fix the fixed pulley so that it is arranged vertically with the steel cable, the motor is used to drive the wire winder to rotate, thereby pulling the trolley to move along the steel cable through the fishing line, and the meter is used to measure the length of the passing fishing line; The trolley comprises a first flat plate, on the top surface of which two first U-shaped plates are arranged at intervals, both of which are arranged in cooperation with a movable pulley through a bearing, the movable pulley is matched with a steel cable, and is connected to a microphone through an adjustment mechanism on the bottom surface of the first flat plate. The adjustment mechanism includes a sleeve, a screw passes through the first plate and is threadedly matched with one end of the sleeve, a connecting rod is arranged inside the other end of the sleeve, and the exposed end of the connecting rod is connected to the opening clamp through an angle adjustment mechanism, the opening clamp is used to fix the microphone, and the angle adjustment mechanism is used to adjust the angle of the opening clamp together with the microphone. A magnet capable of attracting a plurality of counterweights is disposed at one end of the bottom surface of the first flat plate, and a positioning bolt connected to the fishing line is disposed at the other end. By adjusting the number of counterweights, the first flat plate is always parallel to the steel cable. A through hole is provided on the side wall of the sleeve, and an adjusting bolt is provided inside the through hole. The two threads cooperate with each other, and the length of the connecting rod extending into the sleeve is adjusted by tightening or loosening the adjusting bolt, thereby adjusting the distance between the microphone and the first flat plate. Combined with the angle adjustment mechanism, the microphone is directed toward the sound source and is always arranged parallel to the first flat plate.

2. The automatic calibration system for anechoic chamber testing according to claim 1, characterized in that: The clamping mechanism includes a second flat plate, a groove for the steel cable to cooperate with is arranged on the top surface of the second flat plate, a plurality of pressure plates are arranged at intervals on the groove, the steel cable is fixed inside the groove by the cooperation of bolts and nuts, and a second U-shaped piece is arranged on the bottom surface of the second flat plate, and the second U-shaped piece is also arranged in cooperation with the fixed pulley through a bearing.

3. The automatic calibration system for anechoic chamber testing according to claim 2, characterized in that: The first flat plate and the second flat plate have the same thickness, the first U-shaped piece and the second U-shaped piece have the same overall structure, the bottoms thereof are planar structures and have the same thickness, and the fixed pulley and the movable pulley also have the same structure.

4. A calibration method for the automatic calibration system for anechoic chamber detection based on claim 1, characterized in that The following steps are involved: Step 1: Set the sound source on the ground of the semi-anechoic chamber or the center of the ground grid of the full anechoic chamber, fix one end of the steel cable next to the sound source through a fixing block, and pass the other end of the steel cable through the trolley, cooperate with the two movable pulleys on it, extend to the top corner of the anechoic chamber and fix it, and then fix the fixed pulley on the steel cable at the top corner position through a clamping mechanism; Step 2: The fishing line on the winding device passes through the meter, around the fixed pulley, and is connected to the positioning bolt of the first flat plate in the trolley. With the help of the adjustment mechanism, the first flat plate and the microphone are parallel to the steel cable, and the microphone is set toward the sound source, and then connected to the multi-channel collector together with the sound source; Step 3: Transmit the detection data of the multi-channel collector and meter counter to the measurement computer through the wireless router to complete the automatic calibration.

5. The calibration method of the automatic calibration system for anechoic chamber detection according to claim 4, characterized in that: The measured data at a distance of 0.5m to 1.5m from the sound source were selected for fitting to obtain the theoretical sound pressure level curve of the free sound field inside the anechoic chamber. During the calculation process, if r0≥0.5, r0=0.4 was uniformly taken to calculate the deviation between the measured sound pressure level and the theoretical sound pressure level.

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