244 results about "Anechoic chamber" patented technology

The invention discloses a noise reduction method and system for a high-performance TWS Bluetooth audio chip, and relates to the technical field of acoustoelectric integration, and the method comprises the steps: collecting an environment noise signal, synchronously obtaining a Bluetooth radio frequency interference signal, converting the Bluetooth radio frequency interference signal into a digital signal through a 24-bit analog-to-digital converter, and outputting a multi-modal noise feature matrix; performing noise separation and reverse sound wave generation on the multi-modal noise characteristic matrix by using a pre-trained lightweight CycleGAN model, and outputting a reverse sound wave signal; monitoring auditory meatus tightness parameters in real time, dynamically adjusting phase offset and frequency response balance parameters of the mixed noise reduction signals, and outputting optimized noise reduction signals adaptive to the current wearing state; and performing parameter calibration on the optimized noise reduction signal through anechoic chamber scene simulation and laser interferometer phase detection to generate a noise reduction control instruction set. According to the invention, the noise interference problem of the TWS earphone in a complex environment is effectively solved.

The invention discloses a silent and noise-reducing oxygen generator, comprising an organic shell, a base is provided at the bottom of the shell, a molecular adsorption tower is provided on one side of the outside of the shell, a solenoid valve is provided at the upper end of the inside of the shell, a turbine fan is provided below the solenoid valve, a muffler is connected to the turbine fan, a muffler chamber is provided at the bottom of the base, a muffler plate is installed in the muffler chamber, a compressor is installed on the muffler plate through a spring assembly, a plurality of groups of mutually parallel partitions are provided at the bottom of the muffler plate, muffler holes are provided on the rear end plate surface of the partition, an air guide arc plate is provided on the front end relative to the outer side of the outermost partition, and an air guide plate is provided at the bottom of the muffler plate; the invention can effectively reduce the airflow sound and nitrogen exhaust noise of the device during oxygen production by taking in air from one side of the upper part of the shell, the airflow changes the exhaust airflow guide and disperses the airflow energy after passing through the muffler chamber and the muffler plate, thereby reducing the noise generated by the exhaust airflow.

The invention discloses an anechoic chamber site performance test method, and relates to the field of anechoic chamber site performance test, and the method comprises the following steps: obtaining frequency response data between receiving and transmitting antennas in an anechoic chamber site; frequency response data between the receiving antenna and the transmitting antenna are converted into a time domain through inverse discrete Fourier transform; obtaining the response of the linear propagation signal between the receiving and transmitting antennas in the time domain; obtaining a response of a reflected wave signal from the anechoic chamber in a time domain; converting the response of a linear propagation signal between receiving and transmitting antennas in a time domain into a frequency domain through discrete Fourier transform to obtain first frequency domain data; converting the response of the reflected wave signal from the anechoic chamber in the time domain to the frequency domain through discrete Fourier transform to obtain second frequency domain data; and testing the field performance of the anechoic chamber according to the first frequency domain data and the second frequency domain data. According to the method, the hardware investment cost for darkroom site verification is reduced.

The utility model relates to the technical field of anechoic chambers, and discloses an anechoic chamber for noise test, which comprises two first wall bodies, second wall bodies are mounted on the inner sides of the first wall bodies, top plates are mounted at the top ends of the first wall bodies and the second wall bodies, two connecting grooves are formed in one side of each first wall body, and the first wall bodies and the second wall bodies are connected through the connecting grooves. Connecting blocks are installed on the two sides of the second wall body correspondingly, the interiors of the connecting grooves are in sliding connection with the connecting blocks, a plurality of silencing units are installed in the first wall body and the second wall body correspondingly, and four connecting plates are installed on the other side of the first wall body. According to the anechoic chamber for the noise test, through the first wall body, the second wall body and the top plate which can be quickly assembled and disassembled, the site preparation and conversion time can be remarkably shortened, the anechoic chamber is particularly suitable for a rental site or an occasion needing frequent migration, the downtime generated by waiting for site preparation is shortened, and therefore the resource utilization rate and the working efficiency are improved; and the total operation cost is reduced.

The invention provides a dynamic controlled wireless field signal simulation method for satellite communication navigation, and relates to the technical field of satellite simulation testing. A software and hardware environment depended by the method comprises a three-dimensional multi-antenna array in a satellite navigation darkroom, a plurality of independent satellite communication navigation signal simulation base bands corresponding to each antenna array element and satellite communication navigation constellation signal simulation mathematical simulation software; on the basis of a three-dimensional multi-antenna array, a method of combining mathematical simulation with channel dynamic instantaneous switching is adopted, so that satellite signals move relatively smoothly among antenna array elements, and signals received by a receiver in a dynamic controlled wireless field are ensured to be consistent in coming direction, high in fidelity and free of interruption compared with signals in an external real environment. The problem of dynamic signal simulation of a satellite communication navigation signal controlled wireless field is solved, a set of complete construction model is established, and a method basis and practical guidance are provided for future satellite navigation and communication navigation fusion test under low orbit enhancement.

The invention discloses a radiation immunity testing device and method for communication equipment, and belongs to the technical field of radiation immunity testing, and the radiation immunity testing device comprises power monitoring equipment, control and conversion equipment, a first antenna group, a second antenna group and signal analysis equipment, the control and conversion equipment is used for generating a modulation signal, adjusting a communication signal transmitted by the signal analysis equipment to obtain a standard communication signal, and filtering a test signal transmitted by the second antenna group to obtain a standard test signal; the power monitoring equipment adjusts the modulation signal transmitted by the control and rotation equipment to obtain an interference signal; the signal analysis equipment obtains a real communication signal and analyzes the standard test signal to obtain a test result; the first antenna group generates an interference electromagnetic field in the anechoic chamber based on an interference signal transmitted by the power monitoring equipment; the second antenna group adjusts the interference electromagnetic field based on the standard communication signal to obtain a test electromagnetic field, and obtains a test signal of the to-be-detected equipment in the test electromagnetic field; according to the invention, by simulating a real electromagnetic field and filtering clutter signals, the test accuracy is significantly improved.

There is provided a propagation environment reproduction device including: an anechoic chamber that blocks an electromagnetic wave from the outside; reconfigurable intelligent surfaces (RISs) that are installed in the anechoic chamber; a RIS control device that provides a control signal to the RISs; a transmission antenna that is installed in the anechoic chamber; a channel emulator that controls a characteristic of an electromagnetic wave transmitted from the transmission antenna; a reception antenna that is installed in the anechoic chamber as an evaluation target; and a control server that controls the RIS control device and the channel emulator. The RIS includes a first RIS that has a characteristic of changing transmittance of the electromagnetic wave according to the control signal and is disposed between the transmission antenna and the reception antenna.

The invention relates to the technical field of electromagnetic testing, and discloses a system-level HIRF radiation and conduction sensitivity comprehensive test device and method.The device comprises an anechoic chamber and tested equipment, the anechoic chamber is located beside a control room, and a transmitting antenna and an optical fiber cable are arranged in the anechoic chamber; wherein the transmitting antenna is used for radiating signals, the optical fiber cable is connected with the interior of the anechoic chamber and the control chamber, the control chamber is located in an external independent area, and a signal generator, a power amplifier, a directional coupler, a power meter, a measurement receiver, a photoelectric converter and a comprehensive test control system are arranged in the control chamber. According to the method, a comprehensive test environment in which radiation and conduction are synchronously applied is constructed, a test level is accurately calibrated in combination with a normalized transfer function based on full-aircraft test data, and a standardized probe layout and an anti-interference measurement link are adopted, so that high-precision sensitivity evaluation of an aircraft system in a real HIRF coupling scene is realized.

Method for characterizing an anechoic chamber and associated devices. The present invention relates to a method for characterizing an anechoic chamber (10), the method comprising a step of: - for several measurement points spatially arranged according to a circle, acquisition of a signal), - conversion of the acquired signals into components, each component being the value of a respective order of the decomposition of the sum of the acquired signals into phase modes, - filtering of each component by application of a compensation filter eliminating the frequency dependence, - estimation of the amplitude and direction of arrival of parasitic scatterers by solving a system of equations according to which each filtered component is equal to a sum of contributions of the parasitic scatterers, each depending on the amplitude and direction of arrival of the scatterer,and - determination of the characterization parameter from the estimated amplitudes and directions of arrival. Figure for the abbreviation: figure 1,

Particular embodiments described herein provide for a system, an apparatus, and a method for provide for a terahertz testing facility for cryogenic near field beam pattern measurement at terahertz frequencies. The vacuum chamber includes an anechoic chamber that includes an antenna under test, a testing chamber that includes testing equipment, and a thermal / radiation shield between the anechoic chamber and the testing chamber, wherein the thermal / radiation shield thermally separates the anechoic chamber and the testing chamber.

The present application relates to a kind of boundary deformation mutual coupling reverberation chamber shielding effectiveness test device and method, it is related to electromagnetic shielding technical field of material, the test device includes flexible shielding cloth reverberation chamber, metal plate, stepper motor group, transmitting antenna, first receiving antenna, second receiving antenna, first spectrum analyzer, second spectrum analyzer and controller;Metal plate is as partition and is divided into transmitting reverberation chamber and receiving reverberation chamber by flexible shielding cloth reverberation chamber, metal plate is closely connected with flexible shielding cloth reverberation chamber around;Test window is set in the center of metal plate, for installing test material;Stepper motor group is used to control the wall deformation of transmitting reverberation chamber and receiving reverberation chamber;First spectrum analyzer is connected with first receiving antenna;Second spectrum analyzer is connected with second receiving antenna;Controller is connected with first spectrum analyzer, second spectrum analyzer and stepper motor group.The present application provides platform and method for accurately testing the shielding effectiveness of material under composite electromagnetic environment.

The invention belongs to the technical field of nonlinear acoustics, and particularly relates to an array amplitude-phase consistency calibration method of a parametric array, a program, equipment and a storage medium. According to the invention, by measuring the amplitude phase response of the high-frequency sound wave emitted by each array element, the amplitude phase response of the difference frequency sound wave is determined and compensated, so that the array amplitude phase consistency calibration of the parametric array in multiple test scenes such as a pool and an anechoic chamber can be realized. The method has high robustness for installation errors, and the calibrated array elements have more consistent difference frequency amplitude-phase response. The method is simple in implementation mode, can be suitable for various test scenes, provides necessary pre-calibration for beam forming of the parametric array, and has high application value.

A measurement system for over-the-air testing of a device for non-terrestrial networks is described. The measurement system includes an anechoic chamber, at least one transmission antenna configured to transmit a source signal, a polarization rotator configured to rotate a polarization state of the source signal transmitted by the transmission antenna, and an electronic circuit configured to control the polarization rotator such that an ionospheric Faraday rotation is simulated. In addition, a user equipment (UE) is described. The UE is configured to measure a polarization direction of a received signal and to report the measured polarization direction by transmitting it as channel state information. Further, a method for emulating and determining a polarization mismatch in non-terrestrial communication systems is described. The method includes a step of establishing a connection between a system simulator and a device under test, wherein the system simulator indicates the used polarization to the device under test.

The invention discloses a darkroom calibration and verification method, device and system for a curved surface phased array antenna, and belongs to the field of antennae, and the method comprises the steps: building a darkroom calibration environment; the phased-array antenna can be rotated through a built darkroom calibration environment, so that the azimuth can be changed from 0 to 360 degrees, and the pitching can be changed from 0 to 90 degrees; the rotation time and angle and the calibration instruction issuing time of the debugging computer are adjusted, so that the rotation time and angle and the calibration instruction issuing time of the debugging computer are mutually cooperated to traverse all azimuth pitching calibration processes, and a calibration result is issued to the storage module, so that the full-link automatic calibration of the curved surface array can be realized in combination with the mechanical arm; the method not only can obtain the phase and amplitude of each channel required by beam forming, but also can detect antenna internal hardware such as an array element, a radio frequency front end, a channel, an AD channel and the like and calculate performance indexes so as to verify a calibration result, and has the advantages of high efficiency, safety and rapidness.

The invention discloses a vehicle cabin sound field reconstruction method based on space energy diagram constraint and deep optimization. The method comprises the following steps: 1) measuring the impulse response of a vehicle-mounted loudspeaker array in a target vehicle cabin in a listening area; (2) space scanning is conducted on the impulse response and the impulse response simulated in the ideal anechoic chamber scene through a delay and beam forming method, sound energy distribution in all preset directions is calculated, and a space energy diagram of an actual sound field and a space energy diagram of a target ideal sound field are generated; 3) calculating the space energy diagram similarity between the two space energy diagrams, and constructing a target function; 4) constructing a neural network, taking random noise as input, outputting a control filter coefficient, and iteratively optimizing the neural network by using a target function; and 5) according to the neural network after iterative optimization, outputting a control filter coefficient of each loudspeaker channel, and loading the control filter coefficient to a sound system in the target vehicle cabin to realize sound field reconstruction in the target vehicle cabin. The invention has better subjective tone quality.

The utility model relates to the technical field of silencers, and discloses an air pipe silencer for a ship. In the utility model, the central anechoic chamber comprises a central anechoic chamber shell and a first anechoic layer fixedly connected inside the central anechoic chamber shell, a second anechoic layer is arranged on one side of the first anechoic layer close to the tapered anechoic chamber, and the silencer is fixedly connected with the pipe orifice of the air pipe through the flange plate. The air flow sequentially passes through the divergent anechoic chamber, the central anechoic chamber and the convergent anechoic chamber and finally flows out of the air supply pipe, when the air flow passes through the central anechoic chamber, the flow speed of the air flow is greatly reduced through cooperation of the first anechoic layer and the second anechoic layer, and meanwhile the anechoic effect is further improved under the action of the divergent anechoic chamber and the convergent anechoic chamber.

The present invention discloses a calibration device and a calibration method for acoustic measurement of surface pulsating pressure. The calibration device includes a signal generator for generating noise and a plane wave generator disposed in an anechoic chamber. The plane wave generator can convert the noise signal generated by the signal generator into a plane wave. A microphone interface for connecting a monitoring microphone is provided on the plane wave generator, so that the monitoring microphone can monitor the plane wave in the plane wave generator. The plane wave generator further includes an output port for outputting the plane wave, and a reference microphone and a measurement microphone of the surface pulsating pressure acoustic measurement device to be calibrated can monitor the plane wave in the plane wave generator through the output port. It further includes a data acquisition module for acquiring data of the monitoring microphone, the reference microphone, and the measurement microphone. The present invention can calibrate the surface pulsating pressure acoustic measurement device, thereby improving the measurement accuracy of the acoustic measurement device.

This invention discloses a system and method for testing the radio frequency interference (RFI) immunity performance of train vehicle equipment. The system includes a test terminal, a mobile terminal, an adjustable bracket, an antenna, and a field strength probe. The mobile terminal houses a power supply and an immunity signal generator. The power supply powers the test terminal and the immunity signal generator, and the immunity signal generator generates and amplifies the RF modulation signal. The test terminal is located on one side of the top of the mobile terminal. This system and method for testing the RFI immunity performance of train vehicle equipment utilizes a mobile terminal connected to the test terminal, antenna, field strength probe, and immunity signal generator to perform RFI immunity testing. The immunity signal generator simulates the RF interference environment, eliminating the need for an anechoic chamber. Testing can be conducted directly within the train carriages after the train assembly is completed and all functions are properly debugged, improving the overall mobility and portability of the testing system.

The utility model discloses a noise reduction device for a heating and heat preservation tank, relates to the technical field of noise reduction equipment structures for heating and heat preservation tanks, and aims to solve the problems that the existing high-temperature steam can generate strong vibration when entering the heating and heat preservation tank with relatively low temperature, and when the high-temperature steam vibrates for a long time, the welding part of the heating and heat preservation tank is possibly subjected to open welding loss. A sealing tank cover is installed above the heating and heat preservation tank, a fixing flange base is arranged at the upper end of the sealing tank cover, an exhaust base is arranged at one end of the fixing flange base, a feeding base is arranged at the other end of the fixing flange base, and a connecting flange base is arranged at one end of the outer wall of the heating and heat preservation tank. A silencing device is installed at one end of the connecting flange base, a silencing chamber is arranged in the silencing device, a sound absorption hole is formed in one end of the silencing chamber, a guide block is arranged at one end of the sound absorption hole, and exhaust through holes are formed in the periphery of the inner wall of the other end of the silencing chamber.

This utility model discloses a support and acoustic testing system used inside an anechoic chamber. The support includes a telescopic rod, a linkage mechanism, and a tray. The telescopic rod has a fixed rod and a movable rod that are slidably engaged. One end of the fixed rod is provided with a fixing part for fixed connection with the side wall of the anechoic chamber. The linkage mechanism includes a guide rod fixedly connected to the movable rod, a swing rod hinged to the guide rod, and a push rod diagonally supported between the guide rod and the swing rod. One end of the push rod is hinged to the swing rod, and the other end is hinged to a slider slidably disposed on the guide rod. The slider is provided with a locking element for locking the slider. The tray is used to place the test object for acoustic testing, and the bottom of the tray is connected to the swing rod. The support of this utility model can easily adjust the position of the test object inside the anechoic chamber, thereby improving the efficiency of acoustic testing.

The application discloses a kind of online calibration methods of multi-antenna navigation darkroom link delay, belong to satellite navigation user equipment test field.The application includes: by metrology / testing, the receiving zero value of calibration receiver at each frequency point is obtained;Navigation signal link delay calibration environment is constructed in multi-antenna navigation darkroom;Single star multi-output navigation signal simulator transmits single star single frequency point test signal;The current channel link delay is obtained by calibration receiver;Change single star multi-output navigation signal simulator output signal frequency point and obtain other frequency point link delay;Change signal output channel and obtain the link delay of each frequency point of other channel.The application can realize the automation online calibration of multi-antenna navigation darkroom link delay, can effectively shorten system calibration time, reduce the advantages of link delay calibration complexity.

The invention belongs to the technical field of acoustics, and discloses an anechoic chamber hoist crane covering acoustic structure which comprises an acoustic transmission perforated plate lower portion, acoustic transmission perforated plate side portions are symmetrically distributed at the two ends of the acoustic transmission perforated plate lower portion, a hanging rod is fixedly connected to the middle of the top of the acoustic transmission perforated plate lower portion, and a hanging ring is fixedly installed at the top of the hanging rod. The two side walls of the top end of the hanging rod are fixedly connected with balance supporting rods. Compared with a traditional hoist crane which is exposed at the top of an anechoic chamber, the hoist crane has the advantages that through the arrangement of the lower part of the sound-transmitting perforated plate and the side part of the sound-transmitting perforated plate, the design of the structure and the material, and the arrangement of the suspender, the hoisting ring and the balance supporting rod, the hoisting efficiency is improved; the whole device has the advantages of being simple in structure, convenient and fast to install and use, perfect in appearance and high in integrating degree with the anechoic chamber, the sound field environment of the anechoic chamber is guaranteed, meanwhile, the requirement for hoisting of the anechoic chamber can be met, and therefore the using effect of the anechoic chamber is guaranteed.

A system performs a method of verifying an anechoic chamber. A plurality of electromagnetic waves propagate from an emitter located within the anechoic chamber. Each electromagnetic wave of the plurality of electromagnetic waves is associated with one of a plurality of configurations between the transmitter and a receiver in the anechoic chamber. A plurality of reflections from a reflective element in the anechoic chamber are received at the receiver. Each of the plurality of reflections corresponds to one of a plurality of configurations. For each of the plurality of reflections, an ellipse indicative of a range of reflective elements is determined. The intersection of each ellipse is positioned to determine the position of the reflective element in the anechoic chamber. The reflectance of the reflective element is compared to a threshold to validate the anechoic chamber.

The invention relates to the technical field of electromagnetic environment effect testing, and discloses a phased array multifunctional electromagnetic environment effect testing system and a calibration method thereof.The system comprises an active array plane, a comprehensive processing extension set, a comprehensive frequency source extension set, an external feed source combination, a superheterodyne receiver and a digital acquisition extension set; wherein the active array plane is provided with a plurality of minimum sub-arrays, each minimum sub-array is composed of at least one active channel and a corresponding radiation antenna unit, and each minimum sub-array is used for receiving one excitation signal to complete power amplification and radiation synthesis; and the path number of the independent excitation signals generated by the comprehensive frequency source extension set corresponds to the number of the minimum subarrays. The calibration method comprises darkroom plane near-field calibration, external feed source combination calibration and active array plane calibration before working. The system and the method provided by the invention have the advantages of relatively strong accurate construction capability of a complex electromagnetic environment, extremely high test flexibility, multi-beam coordination and high-precision full-link calibration, and stable and reliable operation.

The present invention discloses a test tool for testing the sound insulation performance of sound-insulating and heat-insulating glass fiber cotton, which includes a fixed frame. The outer side of the fixed frame is connected to the walls of an anechoic chamber and a reverberation chamber. A communication channel is provided in the middle of the fixed frame, and the communication channel connects the anechoic chamber and the reverberation chamber. A movable plate is embedded at the port near the reverberation chamber end in the communication channel, and the movable plate is fixed to the fixed frame through quick clamps; the movable plate sequentially includes a sealing member, a first aluminum plate layer, a first lamination frame, a first wire mesh, a sample layer, a second wire mesh, a second lamination frame, and a second aluminum plate layer. The sealing member is close to the reverberation chamber side, and the second aluminum plate layer is close to the anechoic chamber side. The present invention can simulate the actual sound insulation performance of glass fiber cotton used for sound insulation and heat insulation, and at the same time can reduce the influence of lateral sound transmission of traditional components on the test results, which is close to the actual use situation, and the test data can better reflect the actual effect.

The utility model relates to the technical field of acoustic detection, and particularly discloses an anechoic chamber, which comprises a wall body provided with an opening; the door assembly comprises a first door plate and a second door plate which are sequentially arranged in the first direction, the first door plate and the second door plate are both located in the opening, and the second door plate is close to the ground relative to the first door plate; the ground wedge module is movably arranged on the ground of the anechoic chamber; wherein the second door plate comprises a first sub-part, a second sub-part and a third sub-part, openings of the first sub-part and the third sub-part are located on the two sides of the opening in the second direction and hinged to the wall body, and the second sub-part is movably arranged between the first sub-part and the third sub-part so as to open and close part of the opening. The ground wedge module is arranged to be movable, the indoor floor and the outdoor floor of the anechoic chamber are designed to be flush so that the ground wedge module can move conveniently, meanwhile, the door assembly is designed, the operation convenience is greatly improved while the cost is reduced, and the working efficiency is improved.

One or more techniques and / or systems relate to an oscillating piston compressor having at least one intake port, a silencer port, and an exhaust port in a head plate. The compressor can include a valve plate connected to the head plate and having a sound-attenuating chamber and an exhaust chamber. The compressor can include at least one silencer selectably connected to the silencer port in the head plate and located within the sound-attenuating chamber. The compressor can include an air tube having a first end selectably connected to the head plate air tube port and a second end disposed within the valve plate exhaust chamber. The air tube can be configured to accelerate air flow from the second end toward the first end.

This application provides an antenna performance evaluation method and apparatus, addressing the problem in existing technologies where larger scattering objects require larger testing environments when the scattering object is significantly larger than the individual antenna. The antenna performance evaluation method includes the following steps: acquiring the radiated electric field measurement results of a single antenna; determining a hypothetical planar electromagnetic field distribution by performing spherical electromagnetic field mapping; calculating the surface electromagnetic field distribution of the single antenna using a backward inversion method based on the hypothetical planar electromagnetic field distribution; and calculating the radiation pattern of the single antenna in the presence of the scattering object based on the surface electromagnetic field distribution and the properties of the scattering object. An apparatus for implementing the above method is also provided. This application eliminates the need to place large scattering objects in an anechoic chamber, requiring only radiated electric field measurements of the individual antenna, significantly reducing the demand for testing space.

This invention discloses an electromagnetic characteristic testing method for a large-scale vacuum anechoic chamber plasma environment, belonging to the field of microwave testing technology. The method includes: setting up an antenna movement device, an antenna protective cover, and a transmitting antenna in a large anechoic chamber; evacuating the large anechoic chamber to a vacuum and providing a stable plasma environment through a plasma source inlet within the chamber; connecting the transmitting and receiving antennas to a vector network analyzer; connecting the vector network analyzer to a computer; and using the computer to control the vector network analyzer to acquire antenna data in the large-scale vacuum anechoic chamber plasma environment, calculating the gain pattern and transmittance. This invention provides a stable large-scale anechoic chamber plasma environment, ensuring the repeatability of electromagnetic characteristic testing. The antenna movement device ensures that the movement state of the receiving antenna at every angle can be obtained, enabling rapid and large-scale acquisition of stable plasma antenna data.

A kind of chassis stone knocking sound evaluation method and device in car is predicted, belong to chassis test technical field.Step S1, third microphone carries out the collection and knock the knocking sound of the knocking point on the bottom guard plate;Step S2, change the angle of bottom guard plate and ground, repeat step S1-S2;Step S3, formulate the sound transmission function ATF2 of the car to be developed;Step S4, the sound transmission function ATF2 of the car to be developed is simulated using anechoic chamber-anechoic test room set, the sound transmission function ATF3 between first anechoic chamber and second anechoic chamber is measured;Step S5, adjust the position of sound insulation part, first sound source and first microphone, the sound transmission function ATF3 between first anechoic chamber and second anechoic chamber is measured, whether the sound transmission function ATF3 and the sound transmission function ATF2 are similar, if yes, then execute step S6, if no, then execute step S5;Step S6, after playing multiple knocking sound using first sound source, it is scored;Step S7, replace bottom guard plate, repeat step S1-S7, complete the evaluation of the knocking sound of the car to be developed.