Sound card point inspection device

Abstract

The embodiment of the utility model discloses a sound card point inspection device. In a specific implementation mode, the device comprises a main control unit, a sine wave generator and a distortion degree fine tuning unit, a first control output end of the main control unit is connected with a control end of the sine wave generator to control the sine wave generator to output sine waves with different frequencies; the distortion degree fine tuning unit is connected with the second control output end of the main control unit so as to automatically adjust the distortion degree of the sine wave based on the output frequency of the sine wave generator; and the sound card receives and tests related parameters of the sine wave. Compared with an audio analyzer, the implementation mode is low in overall cost and small in size; at different frequency points, parameters of the distortion suppression circuit can be automatically adjusted, sine waves with extremely low distortion are output, and the circuit can be suitable for various high-performance sound cards; according to the utility model, whether the sound card has problems is judged by comparing the audio parameters of the sine wave measured by the sound card with the audio parameters of the output sine wave, the operation is simple, and the device can be conveniently put into use in a production line.

Description

Technical Field

[0001] The utility model relates to the field of sound card spot inspection, and more specifically, to a sound card spot inspection device. Background Art

[0002] Portable audio components (such as microphones and headphones) are becoming increasingly common, and the demand for audio quality is becoming increasingly demanding. On audio component production lines, specialized high-performance sound cards are often used to measure various audio parameters to verify component performance.

[0003] During the audio component production process, key measurement parameters of the sound card must be regularly checked (for example, after a shift change and before a new team begins work) to confirm that they are normal and ensure the effectiveness and accuracy of the measurement. The most accurate method currently available is to use a professional audio analyzer for sound card inspection. However, audio analyzers are expensive, bulky, complex to operate, and require high operator skills, making them unsuitable for widespread use on production lines. Utility Model Content

[0004] The purpose of the utility model is to provide a sound card inspection device to solve the problems in the prior art of audio analyzers being expensive, bulky, complicated to operate, requiring high operator requirements, and not being widely used on production lines.

[0005] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0006] The utility model provides a sound card inspection device, comprising:

[0007] Main control unit, sine wave generator and distortion fine-tuning unit;

[0008] The first control output terminal of the main control unit is connected to the control terminal of the sine wave generator to control the sine wave generator to output sine waves of different frequencies;

[0009] The distortion fine-tuning unit is connected to the second control output terminal of the main control unit to automatically adjust the distortion of the sine wave based on the output frequency of the sine wave generator;

[0010] The sound card receives and tests relevant parameters of the sine wave.

[0011] Furthermore, the distortion fine-tuning unit is a digital potentiometer.

[0012] Furthermore, the sine wave generator includes a first integrator circuit, a second integrator circuit, a digital potentiometer, and a junction field-effect transistor. The feedback signal of the first integrator circuit and the feedback signal of the second integrator circuit are respectively connected to a first feedback input terminal and a second feedback input terminal of the digital potentiometer. The center tap of the digital potentiometer is connected to the gate of the junction field-effect transistor. The tap position of the digital potentiometer at a preset frequency is adjusted in real time based on the feedback signal to adjust the distortion of the sine wave.

[0013] Furthermore, the sine wave generator includes a summing circuit, a first integrating circuit, a second integrating circuit, an output buffer circuit, an amplitude detection circuit, a digital potentiometer, a junction field effect transistor, and a first resistor;

[0014] The first control output terminal of the main control unit is connected to the control terminal of the first integration circuit and the control terminal of the second integration circuit;

[0015] The first input end of the summing circuit is connected to the output end of the first integrator circuit and the output end of the second integrator circuit, and the second end is connected to one end of the first resistor, the drain of the junction field-effect transistor, the first feedback input end of the digital potentiometer, and the output end of the first integrator circuit. The output end of the summing circuit is connected to the input end of the first integrator circuit; the output end of the first integrator circuit is connected to the input end of the second integrator circuit and feeds back a signal to the first feedback input end of the digital potentiometer; the output end of the second integrator circuit is connected to the input end of the amplitude detection circuit and the input end of the output buffer circuit; the output end of the amplitude detection circuit is connected to the second feedback input end of the digital potentiometer and feeds back a signal to the second feedback input end of the digital potentiometer; the center tap of the digital potentiometer is connected to the gate of the junction field-effect transistor, and the control end is connected to the second control output end of the main control unit; the source of the junction field-effect transistor and the other end of the first resistor are grounded; and the output end of the output buffer circuit is connected to the sine wave measurement end of the sound card.

[0016] Furthermore, the sound card inspection device also includes a storage unit connected to the main control unit.

[0017] Furthermore, the sound card inspection device further includes a current measuring unit, and the current measuring unit includes:

[0018] a switch, a second resistor, an operational amplifier, a filter, and an analog-to-digital converter;

[0019] The switch input end is connected to the constant current source output end of the sound card, the control end is connected to the third control output end of the main control unit, the output end is connected to one end of the second resistor and the first input end of the operational amplifier; the other end of the second resistor and the second input end of the operational amplifier are grounded; the output end of the operational amplifier is connected to the filter input end, the filter output end is connected to the analog-to-digital converter input end, and the output end of the analog-to-digital converter is connected to the current signal input end of the main control unit.

[0020] Furthermore, the sound card inspection device further includes a display unit, and the display unit is connected to the display output end of the main control unit.

[0021] Furthermore, the sound card inspection device further includes a mode selection unit, and the mode selection unit is connected to the mode selection input terminal of the main control unit.

[0022] Furthermore, the mode selection unit includes a dip switch.

[0023] Furthermore, the main control unit also includes a data communication terminal for performing data interaction with a terminal device.

[0024] The beneficial effects of the utility model are as follows:

[0025] Compared to an audio analyzer, the sound card inspection device of the present invention has low overall cost and a small size. The distortion fine-tuning unit is connected to the second control output terminal of the main control unit to automatically adjust the distortion of the sine wave based on the output frequency of the sine wave generator. This enables the present invention to automatically and intelligently adjust the parameters of the distortion suppression circuit at different frequency points to output a sine wave with extremely low distortion, making it suitable for various high-performance sound cards. The present invention connects the first control output terminal of the main control unit to the control terminal of the sine wave generator to control the sine wave generator to output sine waves of different frequencies. The audio parameters of the sine wave measured by the sound card are compared with the audio parameters of the output sine wave to determine whether there is a problem with the sound card. The device is simple to operate and convenient for use in production lines. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The specific implementation of the present invention will be further described in detail below with reference to the accompanying drawings.

[0027] Figure 1 A schematic structural diagram of a sound card inspection device provided by an embodiment of the present utility model is shown.

[0028] Figure 2 A circuit diagram of a sine wave generator provided by an embodiment of the present utility model is shown.

[0029] Figure 3 A circuit diagram of a current measuring unit provided by an embodiment of the present utility model is shown.

[0030] Figure 4 A schematic structural diagram of the interaction between a sound card inspection device and a terminal device provided by another embodiment of the present invention is shown. DETAILED DESCRIPTION

[0031] In order to more clearly illustrate the present invention, the present invention is further described below in conjunction with the embodiments and drawings. Similar components in the drawings are represented by the same reference numerals. Those skilled in the art should understand that the following detailed description is illustrative rather than restrictive and should not be used to limit the scope of protection of the present invention.

[0032] like Figure 1 As shown, the utility model provides a sound card inspection device, comprising:

[0033] Main control unit, sine wave generator and distortion fine-tuning unit;

[0034] The first control output terminal of the main control unit is connected to the control terminal of the sine wave generator to control the sine wave generator to output sine waves of different frequencies;

[0035] The distortion fine-tuning unit is connected to the second control output terminal of the main control unit. The distortion fine-tuning unit automatically adjusts the distortion of the sine wave based on the output frequency of the sine wave generator.

[0036] The sound card receives and tests relevant parameters of the sine wave.

[0037] In one possible implementation, the sound card receives and tests relevant parameters of the sine wave and feeds back the parameters to the terminal device. The terminal device compares the detected parameter data with standard data to determine whether the sound card is in a normal state.

[0038] In this embodiment, the distortion fine-tuning unit is a digital potentiometer, and the main control unit is used to drive the sine wave generator to output a sine wave with a preset frequency to the sound card when the sound card inspection device is in audio output mode; and send the tap position signal of the digital potentiometer at the preset frequency to the distortion fine-tuning unit, so as to achieve the lowest distortion level of the reproduced output sine wave at the current frequency.

[0039] In the above embodiment, the working mode of the sound card needs to be configured as the audio parameter measurement mode to test the relevant parameters of the sine wave.

[0040] By comparing the audio parameters measured by the sound card (detected parameter data) with the audio parameters output by the sound wave generator (standard data), it is determined whether the sound card is qualified.

[0041] Compared to an audio analyzer, the sound card inspection device of the present invention has low overall cost and small size. The distortion fine-tuning unit is connected to the second control output terminal of the main control unit to automatically adjust the distortion of the sine wave based on the output frequency of the sine wave generator. This enables the present invention to automatically and intelligently adjust the parameters of the distortion suppression circuit at different frequency points to output a sine wave with extremely low distortion, making it suitable for various high-performance sound cards. The present invention connects the first control output terminal of the main control unit to the control terminal of the sine wave generator to control the sine wave generator to output sine waves of different frequencies. The audio parameters of the sine wave measured by the sound card are compared with the audio parameters of the output sine wave to determine whether there is a problem with the sound card. The operation is simple and convenient for use in the production line.

[0042] In a possible implementation, the distortion fine-tuning unit is a digital potentiometer.

[0043] The sine wave generator in this embodiment is an extremely low-distortion sine wave generator, primarily a state-variable oscillator. It includes a first integrator circuit, a second integrator circuit, a digital potentiometer, and a junction field-effect transistor (JFET) Q1. By adjusting the resistor and capacitor parameters within the first and second integrator circuits, the output sine wave frequency can be adjusted according to inspection requirements.

[0044] The feedback signal FB1 from the first integrator and the feedback signal FB2 from the second integrator are connected to the first feedback input terminal 1 and the second feedback input terminal 3 of the digital potentiometer, respectively. The center tap of the digital potentiometer is connected to the gate of the junction field-effect transistor Q1. Different positions of the center taps result in different voltages applied to the gate of Q1, varying the degree of conduction between its drain and source, and thus varying the equivalent resistance. This difference in the degree to which this equivalent resistance resembles an ideal resistor affects the distortion of the output sine wave.

[0045] The digital potentiometer tap position is adjusted in real time based on the feedback signal, so as to achieve the purpose of minimizing the distortion of the output sine wave at the current frequency.

[0046] Furthermore, if Figure 2 As shown, the sine wave generator includes a summing circuit, a first integrating circuit, a second integrating circuit, an output buffer circuit, an amplitude detection circuit, a digital potentiometer, a junction field effect transistor Q1 and a first resistor R1;

[0047] The first control output terminal of the main control unit is connected to the control terminal of the first integration circuit and the control terminal of the second integration circuit;

[0048] The first input end of the summing circuit is connected to the output end of the first integrator circuit and the output end of the second integrator circuit, and the second end is connected to one end of the first resistor R1, the drain of the junction field effect transistor Q1, the first feedback input end 1 of the digital potentiometer, and the output end of the first integrator circuit. The output end of the summing circuit is connected to the input end of the first integrator circuit; the output end of the first integrator circuit is connected to the input end of the second integrator circuit, and a feedback signal FB1 is fed back to the first feedback input end 1 of the digital potentiometer; the output end of the second integrator circuit is connected to the input end of the amplitude detection circuit and the input end of the output buffer circuit; the output end of the amplitude detection circuit is connected to the second feedback input end 3 of the digital potentiometer, and the feedback signal FB1 is fed back to the second feedback input end 3; the center tap of the digital potentiometer is connected to the gate of the junction field effect transistor Q1, and the control end is connected to the second control output end of the main control unit; the source of the junction field effect transistor Q1 and the other end of the first resistor R1 are grounded; and the output end of the output buffer circuit is connected to the sine wave measurement end of the sound card.

[0049] In one embodiment, Figure 2 As shown, this embodiment further includes a third resistor R3, a fourth resistor R4, and a fifth resistor R5. In this embodiment, the first input terminal of the summing circuit is connected to one end of the third resistor R3 and one end of the fourth resistor R4. The other end of the third resistor R3 is connected to the output end of the first integration circuit. The other end of the fourth resistor R4 is connected to the output end of the second integration circuit. The second end of the summing circuit is connected to one end of the first resistor R1, the drain of the junction field effect transistor Q1, the first feedback input terminal 1 of the digital potentiometer, and one end of the fifth resistor R5. The other end of the fifth resistor R5 is connected to the output end of the first integration circuit and the input end of the second integration circuit. The third resistor R3, the fourth resistor R4, and the internal resistance of the summing circuit determine the amplification factor of the feedback signal. The fifth resistor R5 affects the magnitude of the feedback signal and may not be provided in other embodiments.

[0050] In one embodiment, the working principle of the sine wave generator is as follows:

[0051] The sine wave generator is primarily a state variable oscillator. Feedback signals FB1 and FB2 are connected to the first feedback input 1 and second feedback input 3 of a digital potentiometer, respectively. The center tap of the digital potentiometer is connected to the gate of a junction field effect transistor (JFET) Q1. Different center tap positions result in different gate voltages applied to Q1, varying the degree of conduction between its drain and source, and thus different equivalent resistances. Different gate voltages on Q1 result in different approximations of this equivalent resistance to an ideal resistor, thus affecting the distortion of the output sine wave. In one embodiment, the sine wave is an extremely low-distortion sine wave.

[0052] By switching the resistance and capacitance parameters inside the integration circuit 1 and the integration circuit 2 through the main control unit, the frequency of the output sine wave can be changed.

[0053] When generating sine wave outputs of varying frequencies, the main control unit controls the center position of the digital potentiometer based on the current frequency parameter, performing a resistance-divider sweep operation. This generates different voltage-divider ratios for feedback signals FB1 and FB2 to control the gate voltage of Q1. During this period, the sine wave output by the sine wave generator will experience varying distortion (as reflected by corresponding changes in parameters such as THD).

[0054] Before testing, this embodiment uses an audio analyzer to measure the THD and other parameter change curves at various frequencies in real time, thereby finding the point at which the output sine wave has the lowest distortion at each frequency. The corresponding parameters such as THD (total harmonic distortion) / THD+N (total harmonic distortion plus noise) are stored, and the current center tap position information of the digital potentiometer is simultaneously stored in a storage unit.

[0055] The optimal THD value achieved for the output sine wave at each frequency often varies, and the corresponding digital potentiometer center tap position for this optimal THD also varies. (For example: at 1kHz, adjusting the digital potentiometer center tap minimizes sine wave distortion (THD = -105dB). However, if a sine wave at another frequency (10kHz) is generated, the resulting sine wave distortion level will vary (THD = -100dB) with the same digital potentiometer center tap position. However, adjusting the digital potentiometer center tap can improve THD to, for example, -104dB. When inspecting the sound card, select a sine wave output at a different frequency. The main control unit reads the digital potentiometer center tap position corresponding to the current frequency from the storage unit, writes it to the digital potentiometer, and controls the digital potentiometer center tap to achieve a specific voltage divider coefficient, thereby reproducing the lowest distortion of the output sine wave at the current frequency.

[0056] In one possible implementation, the sound card inspection device also includes a storage unit connected to the main control unit, which is used to store the characteristic parameters of the sine wave at each frequency measured by the audio analyzer and the digital potentiometer tap position signal corresponding to the sine wave distortion at each frequency.

[0057] More specifically, the data stored in the storage unit is a sine wave at multiple frequencies, and a professional audio analyzer is used to measure the characteristic parameters (frequency / amplitude / THD / THD+N, etc.) at different set frequencies.

[0058] In a possible implementation, the characteristic parameters include multiple frequencies, and amplitudes, total harmonic distortion values, and total harmonic distortion plus noise values corresponding to each frequency.

[0059] In one possible implementation, Figure 3As shown, the inspection device further includes a current measuring unit, which includes: a switch S1, a second resistor R2, an operational amplifier, a filter, and an analog-to-digital converter.

[0060] The input end of switch S1 is connected to the constant current source output end of the sound card, the control end is connected to the third control output end of the main control unit, and the output end is connected to one end of the second resistor R2 and the first input end of the operational amplifier; the other end of the second resistor R2 and the second input end of the operational amplifier are grounded; the output end of the operational amplifier is connected to the input end of the filter, the output end of the filter is connected to the input end of the analog-to-digital converter, and the output end of the analog-to-digital converter is connected to the current signal input end of the main control unit.

[0061] The main control unit controls switch S1 to close. Second resistor R2 (a low-noise power resistor) acts as an analog load, forming a complete current loop with the sound card's constant current source. The current output by the sound card's constant current source creates a voltage difference across R2. This voltage difference is amplified by a subsequent high-input impedance operational amplifier, then filtered and fed into an analog-to-digital converter (ADC) for digital conversion. The main control unit periodically reads the ADC's conversion value to determine whether the current is within the specified range. Through data processing, it analyzes the current's stability (the range of fluctuations over time).

[0062] The main control unit sends the measured current value and deviation to the display unit for display; and synchronously sends the data to the terminal device for display.

[0063] The analog-to-digital converter can be a separate chip or an analog-to-digital converter built into the main control unit.

[0064] When the current measurement function is turned off, the main control unit controls the switch S1 to be open, so that the electrical connection between the second resistor R2 and the constant current source of the sound card is disconnected.

[0065] In this embodiment, when the sound card inspection device is in the current measurement mode, the sound card is configured in the constant current source output mode, and the output current of the sound card is set; at this time, the constant current source module of the sound card outputs the set current, and the current measurement unit is driven by the main control unit to turn on the switch S1 to measure the current value of the sound card output current, and the collected current value is output to the main control unit. The sound card is judged to be qualified by comparing the set current with the current actually measured by the current measurement unit.

[0066] In a possible implementation, the sound card inspection device further includes a display unit, which is connected to a display output terminal of the main control unit.

[0067] The display unit is used to display the main parameters of the sine wave currently output by the sine wave generator, including frequency / amplitude / THD (total harmonic distortion) / THD+N (total harmonic distortion plus noise value) and the like.

[0068] In a possible implementation, the sound card inspection device further includes a mode selection unit, which is connected to a mode selection input terminal of the main control unit.

[0069] In this embodiment, the working mode of the inspection system can be manually selected by switching means such as a dip switch; for example, when the dip switch is 0, it is the audio parameter measurement mode, and when the dip switch is 1, it is the constant current source measurement mode.

[0070] In one possible implementation, the main control unit further includes a data communication terminal for performing data interaction with the terminal device.

[0071] like Figure 4 As shown, the working principle of this embodiment is as follows:

[0072] Check the audio measurement performance of the sound card:

[0073] Control the sound card, drive the main control unit through the terminal device or enable the sound card's audio parameter measurement mode through the main control unit's preset automatic inspection program, and measure multiple parameters of the sound card input signal (frequency / amplitude / THD / THD+N, etc.).

[0074] A main control unit selects one of the frequencies from a plurality of stored frequencies as a preset frequency for the sine wave output.

[0075] The working mode of the sound card inspection device is set to audio output mode by manual dialing or through terminal equipment communication; the main control unit drives the sine wave generator to output a sine wave including a preset frequency and specific parameters (such as amplitude) corresponding to the preset frequency.

[0076] The main control unit outputs a sine wave of corresponding frequency / amplitude through the sine wave generator, and automatically reads the digital potentiometer tap position signal corresponding to the lowest distortion point of the sine wave at the preset frequency stored in the storage unit. The sine wave generator is adjusted through the distortion fine-tuning unit to mainly improve its second harmonic and third harmonic, thereby minimizing the total harmonic distortion THD of the sine wave at the current frequency / amplitude.

[0077] At this time, the display unit displays the preset frequency corresponding to the sine wave and the specific parameters corresponding to the preset frequency through the main control unit. The display unit can also be controlled by the main control unit to display the audio parameters measured by the sound card and the output current; the above data can be synchronously transmitted to the terminal device through the main control unit; the specific parameters include the preset frequency and the amplitude corresponding to the preset frequency, THD, and THD+N, etc.

[0078] The audio parameters measured by the sound card are compared with the corresponding parameters displayed by the inspection circuit through terminal equipment or manual comparison to determine whether the results measured by the sound card are normal.

[0079] When inspecting a sound card's audio measurement performance, the specific principle for judging it is that the sine wave measured by the sound card—that is, the sine wave generated by the sine wave generator—should meet or substantially exceed the THD / THD+N parameter specifications for typical sound cards. For example, the maximum THD (similar to the purity of a waveform, with the more negative the value, the purer) a sound card can measure is -90dB, while the THD for a low-distortion sine wave is -100dB. If the sound card measures a sine wave with a THD of -90dB (less than the actual sine wave parameters, but within the sound card's limits), the sound card is functioning properly. If the measured THD is only -80dB, it indicates a problem with the card and reduced accuracy.

[0080] Check the constant current output function of the sound card:

[0081] Control the sound card, drive the main control unit through the terminal device or enable the constant current output mode of the sound card through the automatic inspection program preset by the main control unit, and set the current parameters.

[0082] The working mode of the sound card inspection device is set to the constant current source measurement mode by manual dialing or through terminal device communication; so that the main control unit enables the current measurement unit, and forms a complete current loop with the current output interface of the sound card through its internal simulated load; so as to measure the output current of the constant current source of the sound card and display it on the display unit; optionally, this embodiment can also synchronously upload relevant current parameters to the terminal device.

[0083] By comparing the current parameters actually measured by the sound card's spot-test device with the current parameters set by the sound card, either through a terminal device or manually, the stability of the sound card's constant-current source output current is determined to confirm whether the sound card's constant-current drive is functioning properly. Therefore, this application can be connected to a terminal device such as a host computer to achieve automatic spot checks.

[0084] It can also be operated manually offline, and has a built-in parameter display unit for easy comparison with the sound card measurement results.

[0085] In this embodiment, the terminal device may be a host computer, a mobile phone, a notebook or other terminal device, and is not limited here.

[0086] In the description of the present disclosure, it should be noted that the orientation or positional relationship indicated by the terms "upper" and "lower" is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present disclosure and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present disclosure. Unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be internal communication between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present disclosure can be understood according to the specific circumstances.

[0087] It should also be noted that, in the description of the present disclosure, relational terms such as first and second, etc., are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply the existence of any such actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variants thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further restrictions, an element defined by the statement "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or device comprising the element.

[0088] Obviously, the above embodiments of the present disclosure are merely examples for clearly illustrating the present disclosure, and are not intended to limit the implementation methods of the present disclosure. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is impossible to enumerate all the implementation methods here. Any obvious changes or modifications derived from the technical solution of the present disclosure are still within the scope of protection of the present disclosure.

Claims

1. A sound card inspection device, characterized in that: include: Main control unit, sine wave generator and distortion fine-tuning unit; The first control output terminal of the main control unit is connected to the control terminal of the sine wave generator to control the sine wave generator to output sine waves of different frequencies; The distortion fine-tuning unit is connected to the second control output terminal of the main control unit to automatically adjust the distortion of the sine wave based on the output frequency of the sine wave generator; The sound card receives and tests relevant parameters of the sine wave.

2. The sound card inspection device according to claim 1, characterized in that: The distortion fine-tuning unit is a digital potentiometer.

3. The sound card inspection device according to claim 2, characterized in that: The sine wave generator includes a first integration circuit, a second integration circuit, a digital potentiometer, and a junction field effect transistor, wherein the feedback signal of the first integration circuit and the feedback signal of the second integration circuit are connected to the first feedback input terminal and the second feedback input terminal of the digital potentiometer respectively, and the center tap of the digital potentiometer is connected to the gate of the junction field effect transistor; The tap position of the digital potentiometer at the preset frequency is adjusted in real time based on the feedback signal to adjust the distortion of the sine wave.

4. The sound card inspection device according to claim 2, characterized in that: The sine wave generator includes a summing circuit, a first integrating circuit, a second integrating circuit, an output buffer circuit, an amplitude detection circuit, a digital potentiometer, a junction field effect transistor and a first resistor; The first control output terminal of the main control unit is connected to the control terminal of the first integration circuit and the control terminal of the second integration circuit; The first input end of the summing circuit is connected to the output end of the first integrator circuit and the output end of the second integrator circuit, and the second end is connected to one end of the first resistor, the drain of the junction field-effect transistor, the first feedback input end of the digital potentiometer, and the output end of the first integrator circuit. The output end of the summing circuit is connected to the input end of the first integrator circuit; the output end of the first integrator circuit is connected to the input end of the second integrator circuit and feeds back a signal to the first feedback input end of the digital potentiometer; the output end of the second integrator circuit is connected to the input end of the amplitude detection circuit and the input end of the output buffer circuit; the output end of the amplitude detection circuit is connected to the second feedback input end of the digital potentiometer and feeds back a signal to the second feedback input end of the digital potentiometer; the center tap of the digital potentiometer is connected to the gate of the junction field-effect transistor, and the control end is connected to the second control output end of the main control unit; the source of the junction field-effect transistor and the other end of the first resistor are grounded; and the output end of the output buffer circuit is connected to the sine wave measurement end of the sound card.

5. The sound card inspection device according to claim 3 or 4, characterized in that: The sound card inspection device further includes a storage unit connected to the main control unit for storing characteristic parameters of the sine wave at each frequency and a digital potentiometer tap position signal corresponding to the sine wave distortion at each frequency.

6. The sound card inspection device according to claim 1, characterized in that: The sound card inspection device further includes a current measuring unit, the current measuring unit includes a switch, a second resistor, an operational amplifier, a filter, and an analog-to-digital converter; The switch input end is connected to the constant current source output end of the sound card, the control end is connected to the third control output end of the main control unit, the output end is connected to one end of the second resistor and the first input end of the operational amplifier; the other end of the second resistor and the second input end of the operational amplifier are grounded; the output end of the operational amplifier is connected to the filter input end, the filter output end is connected to the analog-to-digital converter input end, and the output end of the analog-to-digital converter is connected to the current signal input end of the main control unit.

7. The sound card inspection device according to claim 1, characterized in that: The sound card inspection device further includes a display unit, which is connected to the display output end of the main control unit.

8. The sound card inspection device according to claim 1, characterized in that: The sound card inspection device further includes a mode selection unit, which is connected to the mode selection input terminal of the main control unit.

9. The sound card inspection device according to claim 8, characterized in that: The mode selection unit includes a dip switch.

10. The sound card inspection device according to claim 1, characterized in that: The main control unit also includes a data communication terminal for performing data interaction with a terminal device.

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