A precision measurement system for in-vehicle audio equalizers

Abstract

This invention discloses a vehicle-mounted audio equalizer accuracy measurement system, comprising an audio analyzer, an audio equalizer, a power amplifier, and a controller. The audio analyzer emits an audio signal. The audio equalizer adjusts the received audio signal according to pre-input theoretical control parameters to obtain the power amplifier input signal. The power amplifier processes the power amplifier input signal to obtain the audio analyzer input signal and outputs it. The audio analyzer analyzes the received audio analyzer input signal to obtain the frequency response curve of the audio equalizer. The controller analyzes the frequency response curve to obtain actual control parameters. This invention provides a vehicle-mounted audio equalizer accuracy measurement system that quantitatively evaluates the effect of the audio equalizer, ensuring that the vehicle's audio performance meets the expected standards.

Description

Technical Field

[0001] This invention relates to the field of audio testing in in-vehicle audio playback systems, and more particularly to an in-vehicle audio equalizer accuracy measurement system. Background Technology

[0002] With the continuous development of smart cockpits, the driving experience in cars is becoming increasingly rich. Users can not only make calls or send text messages using their mobile phones, but also play music. To provide users with a better audio environment, many cars now offer graphic or parametric in-vehicle audio equalizers. Users can set the audio equalizer to a specific mode (such as folk mode, traditional Chinese style mode, country mode, etc.) according to their needs, and can also adjust various control parameters of the audio equalizer to achieve their desired effect.

[0003] During the development of in-vehicle audio equalizers, it is necessary to test the output audio signal to determine whether the audio output after passing through the equalizer contains noise and whether the output audio signal meets the expected standards. Currently, most performance evaluation methods for in-vehicle audio equalizers still adopt subjective traditional audio-visual methods. The main drawback of this method is that subjective evaluation is related to the evaluator's experience, external environmental factors, and personal psychological factors. Furthermore, some weak noises may not be perceptible to the human ear, and the human ear cannot determine whether the audio playback system meets the expected value in equalizer mode. This makes the sound effect evaluation results susceptible to interference from the external environment and the evaluator's psychology, thus affecting the authenticity and accuracy of the audio equalizer.

[0004] In summary, there is currently limited research on the accuracy testing of in-vehicle audio equalizers. Existing methods do not address whether the output signal after passing through the equalizer meets the expected value, thus compromising the sound quality of in-vehicle intelligent audio playback systems.

[0005] The above background information is provided only to assist in understanding the inventive concept and technical solution of this invention. It does not necessarily belong to the prior art of this patent application, nor does it necessarily provide technical teaching. In the absence of clear evidence that the above information was disclosed before the filing date of this patent application, the above background information should not be used to evaluate the novelty and inventiveness of this application. Summary of the Invention

[0006] The purpose of this invention is to provide a vehicle audio equalizer accuracy measurement system to determine the frequency response curve of the audio equalizer, quantitatively evaluate the effect of the audio equalizer, and ensure that the vehicle audio effect meets the expected standard.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] This invention provides a precision measurement system for in-vehicle audio equalizers, the precision measurement system comprising:

[0009] An audio analyzer having an input terminal and an output terminal, the audio analyzer being able to emit audio signals;

[0010] An audio equalizer, comprising a filter, having an input terminal and an output terminal, wherein the input terminal of the audio equalizer is connected to the output terminal of the audio analyzer, and the audio equalizer can adjust the received audio signal according to pre-input theoretical control parameters to obtain the power amplifier input signal;

[0011] A power amplifier having an input terminal and an output terminal, wherein the input terminal of the power amplifier is connected to the output terminal of the audio equalizer, and the output terminal of the power amplifier is connected to the input terminal of the audio equalizer, and the power amplifier is capable of processing the input signal of the power amplifier to obtain the input signal of the audio analyzer and outputting it.

[0012] A controller having an input terminal and an output terminal, wherein the input terminal of the controller is connected to the output terminal of the audio analyzer and the output terminal of the audio equalizer;

[0013] The audio analyzer can analyze the received input signal to obtain and output the frequency response curve of the audio equalizer;

[0014] The controller can analyze the frequency response curve to obtain actual control parameters, compare the actual control parameters with the theoretical control parameters to obtain an error curve, and store and / or output it.

[0015] Furthermore, the theoretical control parameters are one or more of the following: center frequency, quality factor, and gain.

[0016] Furthermore, the filter is one or more of the following: low pass filter, high pass filter, all pass filter, low shelf filter, high shelf filter, and peaking filter.

[0017] Furthermore, the filter is a peaking filter, and its frequency response function is:

[0018]

[0019] In this context, variable w0 corresponds to the center frequency f0 of the filter, variable w represents the angular frequency relative to the continuous system and the continuous signal, and w = 2πf, variable f represents the actual frequency of the system, variable q represents the original quality factor of the filter, variable dB represents the gain of the filter, j is a complex unit, q1 is the first quality factor of the filter, and q2 is the second quality factor of the filter.

[0020] Furthermore, the actual control parameters include the center frequency f1 and the gain gain1, and the theoretical control parameters include the center frequency f0. Let w = w0, then...

[0021]

[0022] Based on this, the gain gain1 is obtained as the dB value corresponding to the center frequency f1, and the center frequency f1 corresponding to the phase of 0° is obtained according to the frequency response curve.

[0023] Furthermore, the actual control parameters include the filter's original quality factor q, let have

[0024]

[0025] have to

[0026]

[0027] Thus, the original quality factor q of the filter is obtained.

[0028] Further, the step of the controller comparing the actual control parameters with the theoretical control parameters to obtain the error curve includes:

[0029] Let the theoretical control parameter be α0, and the corresponding actual control parameter be α, then the corresponding error is...

[0030]

[0031] Furthermore, the audio equalizer includes multiple cascaded filters. The audio analyzer can obtain the frequency response characteristic curves of each filter and the frequency response characteristic curve of the audio equalizer. The controller calculates the theoretical control parameters of the audio equalizer based on the frequency response characteristic curves of each filter, calculates the actual control parameters of the audio equalizer based on the frequency response characteristic curve of the audio equalizer, compares the actual control parameters with the theoretical control parameters, obtains an error curve, and stores and / or outputs it.

[0032] Furthermore:

[0033] When the number of filters is M, the center frequencies of the theoretical control parameters of the M filters are respectively f F_1 f F_2 , ..., f F_M The gains in the theoretical control parameters are gain1, gain2, ..., gain. M The audio analyzer acquires the frequency response curves of the M filters respectively, thereby determining the frequency response curve of each filter at the center frequency f. F_1 f F_2 , ..., f F_M The gain in the actual control parameters;

[0034] The actual gain of the first filter is denoted as ,..., The actual gain of the second filter is denoted as ,..., And so on;

[0035] Obtain the overall frequency response curve of the audio equalizer and analyze its relationship with the center frequency f. F_1 f F_2 , ..., f F_M The corresponding actual control parameters are denoted as gain′1, gain′2, ..., gain′ M ;

[0036] The gain of the audio equalizer in the theoretical control parameters is:

[0037]

[0038] The gain error of the audio equalizer is

[0039]

[0040] The accuracy error of the audio equalizer is

[0041] err = max{err(f F_1 ), err(f F_2 ), ..., err(f F_M )},

[0042] The error curve of the audio equalizer is obtained accordingly.

[0043] Furthermore, the multiple filters can be selected and used in any combination of number and type.

[0044] The beneficial effects of the technical solution provided by this invention are as follows:

[0045] (1) Quantitatively evaluate the effect of the audio equalizer;

[0046] (2) Determine the accuracy of different types of filters to realize the design of a high-precision multi-segment variable amplitude, frequency band and quality factor audio equalizer in the vehicle;

[0047] (3) Determine the frequency response curve after the audio equalizer to ensure that the in-vehicle sound effect meets the expected standard. Attached Figure Description

[0048] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0049] Figure 1 This is a schematic diagram of the module of the vehicle audio equalizer accuracy measurement system provided in an embodiment of the present invention;

[0050] Figure 2 A schematic diagram of a single-filter vehicle audio equalizer accuracy measurement system provided in an embodiment of the present invention;

[0051] Figure 3 This is a schematic diagram illustrating how the in-vehicle audio equalizer accuracy measurement system, provided in this embodiment of the invention, determines the center frequency based on the phase frequency characteristic curve.

[0052] Figure 4 This is a schematic diagram illustrating how the vehicle audio equalizer accuracy measurement system determines the gain based on the phase frequency response curve, as provided in this embodiment of the invention.

[0053] Figure 5 This is a schematic diagram of the error curve of the center frequency of the in-vehicle audio equalizer accuracy measurement system provided in this embodiment of the invention.

[0054] Figure 6 This is a schematic diagram of the error curve of the quality factor of the in-vehicle audio equalizer accuracy measurement system provided in this embodiment of the invention.

[0055] Figure 7 This is a schematic diagram of the gain error curve of the in-vehicle audio equalizer accuracy measurement system provided in this embodiment of the invention. Detailed Implementation

[0056] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0057] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, apparatus, product, or device that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or devices.

[0058] Audio equalizers are important tuning tools for in-vehicle intelligent audio playback systems. The purpose of this invention is to measure the accuracy of in-vehicle audio equalizers, laying the foundation for the realization of intelligent in-vehicle audio playback systems.

[0059] See Figure 1 In one embodiment of the present invention, an in-vehicle audio equalizer accuracy measurement system is provided, the accuracy measurement system comprising:

[0060] An audio analyzer having an input terminal and an output terminal, the audio analyzer being able to emit audio signals;

[0061] An audio equalizer, comprising a filter, having an input terminal and an output terminal, wherein the input terminal of the audio equalizer is connected to the output terminal of the audio analyzer, and the audio equalizer can adjust the received audio signal according to pre-input theoretical control parameters to obtain the power amplifier input signal;

[0062] A power amplifier having an input terminal and an output terminal, wherein the input terminal of the power amplifier is connected to the output terminal of the audio equalizer, and the output terminal of the power amplifier is connected to the input terminal of the audio equalizer, and the power amplifier is capable of processing the input signal of the power amplifier to obtain the input signal of the audio analyzer and outputting it.

[0063] A controller having an input terminal and an output terminal, wherein the input terminal of the controller is connected to the output terminal of the audio analyzer and the output terminal of the audio equalizer;

[0064] The audio analyzer can analyze the received input signal to obtain and output the frequency response curve of the audio equalizer;

[0065] The controller can analyze the frequency response curve to obtain actual control parameters, compare the actual control parameters with the theoretical control parameters to obtain an error curve, and store and / or output it.

[0066] Quantifying the performance of audio equalizers allows for accurate performance evaluation, facilitating comparison with standards and enabling the production of mass-produced products with consistent performance.

[0067] See Figure 1 and Figure 2 In one embodiment of the present invention, the theoretical control parameter is one or more parameters selected from center frequency, quality factor, and gain.

[0068] In one embodiment of the present invention, the filter is one or more of the following: low pass filter, high pass filter, all pass filter, low shelf filter, high shelf filter, and peaking filter.

[0069] In one embodiment of the present invention, the audio equalizer includes one filter, which is a peaking filter, and its frequency response function is:

[0070]

[0071] In this context, variable ω0 corresponds to the center frequency f0 of the filter, variable ω represents the angular frequency relative to the continuous system and the continuous signal, and ω=2πf, variable f represents the actual frequency of the system, variable q represents the original quality factor of the filter, variable dB represents the gain of the filter, j is a complex unit, q1 is the first quality factor of the filter, and q2 is the second quality factor of the filter.

[0072] In one embodiment of the present invention, the actual control parameters include the center frequency f1 and the gain gain1, and the theoretical control parameters include the center frequency f0. Let ω = ω0, then...

[0073]

[0074] Therefore, the gain gain1 is obtained as the dB value corresponding to the center frequency f1, and the center frequency f1 corresponding to the phase of 0° is obtained according to the frequency response curve. See [link to relevant documentation]. Figure 3 and Figure 4 , Figure 3 The intersection of the curves indicates the center frequency f1. Figure 4 The intersection of the curves indicates the gain.

[0075] In one embodiment of the present invention, the actual control parameters include the original quality factor q of the filter, let have

[0076]

[0077] have to

[0078]

[0079] Thus, the original quality factor q of the filter is obtained.

[0080] In one embodiment of the present invention, the step of the controller comparing the actual control parameters with the theoretical control parameters to obtain an error curve includes:

[0081] Let the theoretical control parameter be α0, and the corresponding actual control parameter be α, then the corresponding error is...

[0082]

[0083] In one embodiment of the present invention, the audio equalizer includes a plurality of cascaded filters. The audio analyzer is capable of obtaining the frequency response characteristic curves of each filter and the frequency response characteristic curve of the audio equalizer. The controller calculates the theoretical control parameters of the audio equalizer based on the frequency response characteristic curves of each filter, calculates the actual control parameters of the audio equalizer based on the frequency response characteristic curve of the audio equalizer, compares the actual control parameters with the theoretical control parameters, obtains an error curve, and stores and / or outputs it.

[0084] In one embodiment of the present invention:

[0085] When the number of filters is M, the center frequencies of the theoretical control parameters of the M filters are respectively f F_1 f F_2 , ..., f F_M The gains in the theoretical control parameters are gain1, gain2, ..., gain. M The audio analyzer acquires the frequency response curves of the M filters respectively, thereby determining the frequency response curve of each filter at the center frequency f.F_1 f F_2 , ..., f F_M The gain in the actual control parameters;

[0086] The actual gain of the first filter is denoted as ,..., The actual gain of the second filter is denoted as ,..., And so on;

[0087] Obtain the overall frequency response curve of the audio equalizer and analyze its relationship with the center frequency f. F_1 f F_2 , ..., f F_M The corresponding actual control parameters are denoted as gain′1, gain′2, ..., gain′ M ;

[0088] The gain of the audio equalizer in the theoretical control parameters is:

[0089]

[0090] The gain error of the audio equalizer is

[0091]

[0092] The accuracy error of the audio equalizer is

[0093] err = max{err(f F_1 ), err(f F_2 ), ..., err(f F_M )},

[0094] The error curve of the audio equalizer is obtained accordingly.

[0095] In one embodiment of the invention, the plurality of filters can be selected and used in any combination of number and type.

[0096] The following is a specific embodiment of the present invention for reference. It should be noted that the instrument models, variable value ranges, etc., used in the following specific embodiment are only to make the technical solution of the present invention easier to understand, and do not constitute a limitation on the scope of protection of the present invention.

[0097] See Figure 1Based on the ADSP-21565 in-vehicle audio equalizer as the experimental platform, measurements were performed on the equalizer. This equalizer is implemented using M cascaded filters. The types of these M filters mainly include: lowpass, highpass, allpass, low shelf, high shelf, and peaking. Users can arbitrarily select the filter type and number according to their needs, and the center frequencies of the M filters will cover the audio signal range of [20Hz 20kHz]. An in-vehicle power amplifier is connected to the audio equalizer, and the audio signal adjusted by the equalizer's control parameters is used as the power amplifier's input signal. An audio analyzer is connected to the power amplifier, and a sweep signal generated by the audio analyzer is used as the input signal to the in-vehicle audio equalizer. The audio signal after passing through the in-vehicle power amplifier is used as the input signal to the audio analyzer to obtain the frequency response curve of the audio equalizer. The controller uses the frequency response curve to calculate the actual equalizer control parameters and compares them with the theoretical equalizer control parameters to determine the error curve of the control parameters. The controller can be independent or integrated into the audio analyzer.

[0098] The audio equalizer is implemented by cascading M filters. The types of the M filters mainly include: low pass, high pass, all pass, low shelf, high shelf, and peaking. The main implementation steps are as follows:

[0099] 1. Measurement of control parameters for single-type digital filters

[0100] This example uses an audio equalizer with only one filter. The following discussion focuses on the peaking filter; the solution process for other filters is similar. A schematic diagram of the peaking filter control parameter measurement is shown below. Figure 2 As shown. Specifically, it includes the following steps:

[0101] ① Determination of the frequency response curve of the peaking filter

[0102] The frequency response curve of the peaking filter is obtained using a portable Audio Precision audio analyzer (model APx555). The APx555 portable audio analyzer enables real-time data transmission and reception with a computer. The amplitude-frequency response curve of the peaking filter is obtained through measurement and analysis using this audio analyzer and transmitted in real time, completing the transfer and storage of three technical parameter information.

[0103] ② Measurement of peaking filter control parameters

[0104] The transfer function of the peaking filter is expressed as:

[0105]

[0106] In equation (1), variable s represents the Laplace transform, ω represents the complex frequency response, variable ω0 represents the center frequency of the filter, variable q represents the quality factor of the filter, and variable dB represents the gain of the filter.

[0107] Let s = jω, where j is the imaginary unit. From equation (1), the frequency response function of the speaking filter can be obtained as follows:

[0108]

[0109] In equation (2), the variable ω represents the angular frequency of the relative continuous system and the continuous signal, and ω = 2πf, while the variable f represents the actual frequency of the system.

[0110] When ω=ω0, equation (2) is expressed as:

[0111]

[0112] From equation (3), we can obtain that the frequency f corresponding to the phase of 0° is the center frequency f1, and the dB value corresponding to the center frequency f0 is the gain value gain1.

[0113] when When, equation (2) is expressed as:

[0114]

[0115] From equation (4), we can obtain the appropriate... The frequency response function at time is:

[0116]

[0117] From equation (5), we can first determine half of the center frequency. The corresponding phase values ​​are then used to calculate the values ​​of q1 and q2 using equation (5).

[0118] ③ Peaking filter control parameter error

[0119] The control parameters of the peaking filter are the center frequency f, the quality factor q, and the gain. Let the input center frequency be f. pk The quality factor is q pk gain pk The calculated center frequency is f′ pk The quality factor is q′ pk gain′ pk The filter control parameter errors are as follows:

[0120]

[0121]

[0122]

[0123] 2. Measurement of control parameters for multi-filter audio equalizers

[0124] The center frequencies of the M cascaded filters in the audio equalizer are set to fm respectively. F_1 f F_2 , ..., f F_M The quality factor is set to q respectively. F_1 q F_2 , ..., q F_M The gain is set to gain respectively. F_1 gain F_2 ,...,gain F_M The frequency response curves of M filters were obtained using an APx555 audio analyzer, thereby determining the frequency response curve of each filter at its center frequency f. F_1 f F_2 , ..., f F_M The gain values ​​of the first filter are respectively... ,..., The gain values ​​of the second filter are respectively ,..., The gain values ​​of the Mth filter are respectively ,..., Simultaneously, obtain the frequency response curve of the audio equalizer and determine that the center frequency is set to f. F_1 f F_2 , ..., f F_M The gain values ​​are denoted as gain′1, gain′2, ..., gain′. M .

[0125] The audio equalizer is set to f at the center frequency. F_1 f F_2 , ..., f F_M The gain values ​​are as follows:

[0126]

[0127] The audio equalizer is set to f at the center frequency. F_1 f F_2 , ..., f F_M The gain errors are as follows:

[0128]

[0129] The accuracy error of the audio equalizer is:

[0130] err = max{err(f F_1 ), err(f F_2 ), ..., err(f F_M )}

[0131] The following is an example of a specific measurement.

[0132] First, determine the accuracy of the single-type filter to ensure the accuracy of the designed audio equalizer. Taking the speaking filter as an example, the control parameters of the speaking filter are: center frequency f, with a value range of [20Hz-20kHz]; quality factor q, with a value range of [0.120]; and gain, with a value range of [-24dB-15dB]. Figure 5 This is a schematic diagram of the error curve for the control parameter center frequency f. Figure 6 This is a schematic diagram of the error curve for the control parameter, quality factor q. Figure 7 This is a schematic diagram of the error curve for the control parameter gain.

[0133] The audio equalizer in this embodiment contains three types of filters, totaling five filters, referred to as a five-band audio equalizer. The filters are second-order high pass, low shelf, peaking, high shelf, and second-order low pass, and their control parameters are shown in Table 1.

[0134] Table 1

[0135] The audio equalizer is set to f at the center frequency. F_1 f F_2 , ..., f F_M The gain values ​​are as follows:

[0136] gain1=-3.254+9.992+0.039-0.001-0.003=6.773

[0137] gain2=0.03+5.168+2.204+0.011+0.011=7.424

[0138] gain3 = -0.01 + 0.154 + 9.991 + 0.052 - 0.006 = 10.181

[0139] gain4=-0.227-0.231+1.202+4.808-0.45=4.902

[0140] gain5=-0.875-0.88-0.549+8.509-3.789=2.416,

[0141] The audio equalizer is set to f at the center frequency. F_1 f F_2 , ..., f F_M The gain errors are as follows:

[0142]

[0143] The accuracy error of this 5-band audio equalizer is:

[0144] err = 4.83%.

[0145] This allows us to derive the error curves corresponding to each control parameter of the audio equalizer, or to obtain the total error curve through weighted processing, thereby quantifying and evaluating the performance of the audio equalizer.

[0146] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0147] The above description is only a specific embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this application, and these improvements and modifications should also be considered within the scope of protection of this application.

Claims

1. A vehicle-mounted audio equalizer accuracy measurement system, characterized in that, The accuracy measurement system includes: An audio analyzer having an input terminal and an output terminal, the audio analyzer being able to emit audio signals; An audio equalizer includes multiple cascaded filters, has an input terminal and an output terminal, the input terminal of the audio equalizer is connected to the output terminal of an audio analyzer, the audio analyzer can obtain the frequency response characteristic curves of each filter and the frequency response characteristic curve of the audio equalizer; the audio equalizer can adjust the received audio signal according to pre-input theoretical control parameters to obtain the power amplifier input signal, the theoretical control parameters including center frequency and gain; A power amplifier having an input terminal and an output terminal, wherein the input terminal of the power amplifier is connected to the output terminal of the audio equalizer, and the output terminal of the power amplifier is connected to the input terminal of the audio equalizer, and the power amplifier is capable of processing the input signal of the power amplifier to obtain the input signal of the audio analyzer and outputting it. The controller has an input terminal and an output terminal. The input terminal of the controller is connected to the output terminal of the audio analyzer and the output terminal of the audio equalizer. The controller calculates the theoretical control parameters of the audio equalizer based on the frequency response curves of each filter. When the number of filters is M, the center frequencies of the theoretical control parameters of the M filters are fm, ... F_1 f F_2 , ..., f F_M The center frequencies of the M filters cover a range from 20Hz to 20kHz; the theoretical control parameters include gains gain1, gain2, ..., gain M They are respectively The audio analyzer can analyze the received input signal and acquire the frequency response curves of the M filters respectively, thereby determining the frequency response curve of each filter at the center frequency f. F_1 f F_2 , ..., f F_M The gain in the actual control parameters, the actual gain of the first filter is denoted as... The actual gain of the second filter is denoted as And so on; and obtain and output the frequency response curve of the audio equalizer, and analyze it to determine its relationship with the center frequency f. F_1 f F_2 , ..., f F_M The corresponding actual control parameters are denoted as gain′1, gain′2, ..., gain′ M ; The controller can analyze the frequency response curve to obtain actual control parameters, compare the actual control parameters with the theoretical control parameters, obtain an error curve, and store and / or output it, including: the gain error of the audio equalizer is... The accuracy error of the audio equalizer is err = max{err(f F_1 ),err(f F_2 ),…,err(f F_M Based on this, the error curve of the audio equalizer is obtained, thereby quantitatively evaluating the performance of the audio equalizer.

2. The accuracy measurement system as described in claim 1, characterized in that, The filter is one of several filters, including low pass filter, high pass filter, all pass filter, low shelf filter, high shelf filter, and peaking filter.

3. The accuracy measurement system as described in claim 2, characterized in that, The theoretical control parameters also include the quality factor; The filter is a peaking filter, and its frequency response function is: In this context, variable ω0 corresponds to the center frequency f0 of the filter, variable ω represents the angular frequency relative to the continuous system and the continuous signal, and ω=2πf, variable f represents the actual frequency of the system, variable q represents the original quality factor of the filter, variable dB represents the gain of the filter, j is a complex unit, q1 is the first quality factor of the filter, and q2 is the second quality factor of the filter.

4. The accuracy measurement system as described in claim 3, characterized in that, The actual control parameters include the center frequency f1 and the gain gain1, and the theoretical control parameters include the center frequency f0. Let ω = ω0, then... Based on this, the gain gain1 is obtained as the dB value corresponding to the center frequency f1, and the center frequency f1 corresponding to the phase of 0° is obtained according to the frequency response curve.

5. The accuracy measurement system as described in claim 3, characterized in that, The actual control parameters include the filter's original quality factor q. Let ω = ω0 / 2, then... have to Thus, the original quality factor q of the filter is obtained.

6. The accuracy measurement system as described in claim 1, characterized in that, The step of the controller comparing the actual control parameters with the theoretical control parameters to obtain the error curve includes: Let the theoretical control parameter be α0, and the corresponding actual control parameter be α, then the corresponding error is...

7. The accuracy measurement system as described in claim 2, characterized in that, The multiple filters can be selected and used in any number and type combination.

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