Interference sound suppression method, analog-to-digital converter and wearable device

Abstract

The invention provides an interference sound suppression method, an analog-to-digital converter and wearable equipment, and relates to the field of audio processing. The interference sound suppression method comprises the following steps: adjusting the configuration of a digital-to-analog converter, so that after a sigma-delta modulator modulates an audio input signal based on a target calibration signal, the interference sound in the obtained audio output signal is within a preset frequency range; the target calibration signal is a calibration signal output by the digital-to-analog converter after configuration adjustment; the preset frequency range is the frequency range of sound not heard by human ears; or, if the audio sigma-delta analog-to-digital converter is connected with the filter, after the filter filters the interference sound in the preset frequency range, the amplitude or power of the interference sound is attenuated to be smaller than the target threshold value. Through the mode, the interference sound cannot be heard by human ears, so that interference sound suppression is realized.

Description

Technical Field

[0001] This application relates to the field of audio processing, and more specifically, to a method for suppressing interference sounds, an analog-to-digital converter, and a wearable device. Background Technology

[0002] Audio sigma-delta ADC (sigma-delta analog-to-digital converter, or Σ-Δ analog-to-digital converter) chips undergo DC (direct current voltage) calibration before leaving the factory.

[0003] However, the DC calibration of the chip before it leaves the factory does not take into account the impact of the actual connected circuitry on the audio sigma-delta ADC. For example, in actual use, the audio sigma-delta ADC is connected to circuitry and a microphone. The circuitry and microphone have a certain noise floor (including DC value), which means that after the audio signal is processed by the sigma-delta ADC, the output audio signal will contain interference. Summary of the Invention

[0004] In view of this, this application aims to provide a method for suppressing interference noise, an analog-to-digital converter, and a wearable device to suppress interference noise from an audio sigma-delta analog-to-digital converter.

[0005] In a first aspect, embodiments of this application provide an interference noise suppression method applied to an audio sigma-delta analog-to-digital converter (ADC) for interference noise suppression. The audio sigma-delta ADC includes a digital-to-analog converter (DAC) and a sigma-delta modulator. The output of the DAC is connected to the input of the sigma-delta modulator. The sigma-delta modulator receives a calibration signal output from the DAC and modulates the audio input signal to the audio sigma-delta ADC based on the calibration signal to obtain an audio output signal. The input terminal of the converter is also connected to an audio input circuit; the interference noise suppression method includes: adjusting the configuration of the digital-to-analog converter so that after the sigma-delta modulator modulates the audio input signal based on a target calibration signal, the interference noise in the audio output signal is within a preset frequency range; the target calibration signal is the calibration signal output by the digital-to-analog converter after the configuration is adjusted; the preset frequency range is the frequency range of sounds that are not audible to the human ear; or, if the audio sigma-delta analog-to-digital converter is connected to a filter, after the filter filters the interference noise within the preset frequency range, the amplitude or power attenuation value of the interference noise is less than a target threshold.

[0006] When an audio sigma-delta analog-to-digital converter (ADC) is connected to a microphone, if sound exists in the audio output signal of the ADC when the voltage of the audio input signal is 0, this sound is interference caused by background noise. Therefore, in this embodiment, an audio input signal with a voltage of 0 can be used to identify interference in the audio sigma-delta ADC, thereby facilitating interference suppression. By adjusting the ADC configuration to a first configuration, in this configuration, the voltage signal output by the ADC and the background noise are modulated by the sigma-delta modulator, which changes the frequency range of the output interference, causing the frequency of the audio output signal composed of interference to exceed the frequency range of sounds audible to the human ear. Thus, the interference will not be audible to the user, reducing its impact; or the amplitude of the interference can be attenuated by the filter attenuation value to less than a target threshold, making the interference close to or less than the background noise, thus making it difficult or impossible for the user to hear.

[0007] In one embodiment, adjusting the configuration of the digital-to-analog converter includes: adjusting the configuration of the digital-to-analog converter to a first configuration, wherein the first configuration is used to make the target calibration value of the output target calibration signal greater than or equal to a first preset threshold; wherein, if an initial audio input signal with an amplitude of 0 is obtained, the sigma-delta modulator modulates the initial audio input signal based on the target calibration signal, and the interference sound in the obtained audio output signal is within the frequency range of the non-human audible sound.

[0008] In this embodiment, by adjusting the configuration of the digital-to-analog converter to a first configuration, the target calibration value of the output target calibration signal is greater than or equal to a first preset threshold. When the target calibration value is greater than or equal to the first preset threshold, the interference frequency of the output signal will be within the frequency range of sounds that are not audible to the human ear. Therefore, the user cannot hear the interference sound, thus achieving interference suppression.

[0009] In one embodiment, the resolution of the digital-to-analog converter is greater than or equal to a preset resolution; the preset-bit digital-to-analog converter allows the output calibration signal with a calibration value greater than or equal to the first preset threshold.

[0010] In this embodiment of the application, the interference suppression method has certain requirements on the resolution of the digital-to-analog converter so that the voltage value of the output calibration signal can be greater than or equal to a first preset threshold. Therefore, a digital-to-analog converter with a resolution greater than or equal to a preset bit can be used so that the calibration signal accurately output by the digital-to-analog converter can be used for the suppression of interference sounds.

[0011] In one embodiment, before adjusting the configuration of the digital-to-analog converter to the first configuration, the method further includes: obtaining a second preset value for the digital-to-analog converter; the second preset value is: the value of the calibration signal output by the digital-to-analog converter when both the input audio signal and the output audio signal are 0 during the initial calibration of the audio sigma-delta analog-to-digital converter; adjusting the configuration of the digital-to-analog converter to the first configuration based on the audio input signal includes: adjusting the configuration of the digital-to-analog converter to increase the first preset value based on the second preset value, such that the target calibration value of the target calibration signal is greater than or equal to the first preset threshold.

[0012] The initial calibration (or factory calibration) of an audio sigma-delta analog-to-digital converter (ADC) can adjust the voltage of the ADC's output signal so that the audio output signal is also 0 when the audio input signal is 0. In this embodiment, the audio sigma-delta ADC that has undergone factory calibration has an audio output signal of 0 when the audio input signal is 0. Therefore, interference noise can be directly suppressed, ensuring that the voltage value of the calibration signal is greater than or equal to a first preset threshold. However, for an audio sigma-delta ADC that has not undergone factory calibration, the output signal is not 0 when the input signal is 0. If the ADC configuration is directly adjusted, the calibration signal output by the ADC may not ensure that the frequency of interference noise is within the preset frequency range. Therefore, a second preset value can be obtained when both the input and output audio signal voltages are 0, and the first preset value is added to the second preset value. This ensures that the voltage value of the calibration signal is greater than or equal to the first preset threshold. Simultaneously, this method can suppress interference noise in audio sigma-delta ADCs that have not undergone factory calibration, expanding the scope of application.

[0013] In one embodiment, after adjusting the configuration of the digital-to-analog converter (DAC) to a first configuration, the method further includes: obtaining the sampling rate change of the audio sigma-delta DAC; adjusting the configuration of the DAC again based on the sampling rate change, so that the sigma-delta modulator modulates the audio input signal based on the target calibration signal output by the DAC after the configuration adjustment, and the interference sound in the resulting audio output signal is within the frequency range of non-human audible sounds; wherein the sampling rate change of the audio sigma-delta DAC is inversely proportional to the change in the target calibration value of the target calibration signal after the DAC configuration adjustment.

[0014] In this embodiment, changes in the sampling rate alter the dynamic range of the audio input signal to the audio sigma-delta analog-to-digital converter (ADC), thereby changing the frequency range of interference sounds. The original calibration signal's target calibration value may no longer ensure that the frequency of the interference sounds in the changed output falls within a preset frequency range. Therefore, the ADC configuration can be adjusted based on the sampling rate change so that the sigma-delta modulator modulates the audio input signal based on the adjusted ADC output calibration signal, still achieving an audio output signal within the preset frequency range. This allows the audio sigma-delta ADC to suppress interference even after sampling rate changes.

[0015] In one embodiment, after adjusting the configuration of the digital-to-analog converter to a first configuration, the method further includes: obtaining the range change of the audio sigma-delta analog-to-digital converter; adjusting the configuration of the digital-to-analog converter again based on the range change, so that the sigma-delta modulator modulates the audio input signal based on the target calibration signal output by the digital-to-analog converter after the configuration is adjusted, and the interference sound in the obtained audio output signal is within the frequency range of non-human audible sound; wherein, the range change of the audio sigma-delta analog-to-digital converter is proportional to the change in the target calibration value of the target calibration signal after the configuration of the digital-to-analog converter is adjusted.

[0016] In this embodiment, a change in the measurement range alters the dynamic range of the audio input signal to the audio sigma-delta analog-to-digital converter (ADC), thereby changing the frequency range of interference sounds. The original calibration signal's target calibration value may no longer ensure that the frequency of the interference sounds in the changed output falls within the preset frequency range. Therefore, the ADC configuration can be adjusted according to the range change, allowing the sigma-delta modulator to modulate the audio input signal based on the adjusted ADC output calibration signal, still achieving an audio output signal within the preset frequency range. This enables the audio sigma-delta ADC to suppress interference even after a range change.

[0017] In one embodiment, the sigma-delta modulator outputs the audio output signal via a quantizer; the quantizer is used to subtract a third preset value from the audio output signal; the third preset value matches the value of the target calibration signal.

[0018] In this embodiment, the sigma-delta modulator can interfere with the frequency of the tone, but it will cause the audio output signal to have an additional voltage value of the calibration signal. The audio output signal may be used by subsequent circuits, and the voltage value of the calibration signal attached to the audio output signal affects the accuracy of the audio output signal. Therefore, a third preset value matching the voltage value of the calibration signal can be subtracted before the audio sigma-delta analog-to-digital converter outputs the audio output signal to improve the accuracy of the audio output signal.

[0019] In one embodiment, the third preset value is the signal value of the audio output signal when the audio input signal is 0 and the digital-to-analog converter is configured as the first configuration.

[0020] Ideally, the amount of voltage added by the digital-to-analog converter (DAC) should correspond to the same voltage subtraction in the quantizer. However, due to various non-ideal characteristics of analog circuits, such as variations in components like resistors, capacitors, and inductors, the actual output signal deviates from the desired output signal. Therefore, in this embodiment, the audio output signal value can be determined as a third preset value when the actual audio input signal is 0 and the DAC is configured in the first setting. This reduces the impact of non-ideal characteristics on the voltage value, allowing the audio output signal to be more accurately subtracted from the value added by the DAC, thus improving the accuracy of the audio output signal.

[0021] In one embodiment, the target calibration value of the target calibration signal is a voltage value. The first configuration includes a preset sequence of multiple voltage values ​​and a sub-configuration of a digital-to-analog converter corresponding to each voltage value, and each voltage value in the preset sequence is greater than the first preset threshold. After adjusting the configuration of the digital-to-analog converter to the first configuration, the method further includes: configuring the digital-to-analog converter to randomly or sequentially select a voltage value from the preset sequence as the target preset voltage value at preset time intervals, and adjusting the configuration of the digital-to-analog converter to the configuration of the digital-to-analog converter corresponding to the target preset voltage value.

[0022] In this embodiment, the voltage of the output signal of the digital-to-analog converter is adjusted at regular intervals, and different voltage values ​​are used to adjust the influence of interference, thereby reducing the situation where interference cannot be suppressed due to changes in the circuit of the audio sigma-delta analog-to-digital converter during use.

[0023] In one embodiment, if the output of the sigma-delta modulator is used to connect to a filter; adjusting the configuration of the digital-to-analog converter includes: adjusting the configuration of the digital-to-analog converter to a second configuration, the second configuration being used to make the target calibration value of the target calibration signal within a second preset threshold range; wherein, the sigma-delta modulator modulates the initial audio input signal based on the target calibration signal within the second preset threshold range, and the interference in the obtained audio output signal satisfies: after the filter filters the interference in the preset frequency range, the amplitude or power of the interference is attenuated to less than the target threshold.

[0024] In this embodiment of the application, by adjusting the configuration of the digital-to-analog converter to the second configuration, the target calibration value of the target calibration signal output by the digital-to-analog converter is within the range of the second preset threshold. As a result, the interference sound modulated by the target calibration signal can be attenuated to less than the target threshold, making it difficult or impossible for the user to hear, thereby achieving noise suppression.

[0025] Secondly, embodiments of this application provide an audio sigma-delta analog-to-digital converter, comprising: a digital-to-analog converter and a sigma-delta modulator; the output terminal of the digital-to-analog converter is connected to the input terminal of the sigma-delta modulator; the sigma-delta modulator is used to receive a calibration signal output by the digital-to-analog converter, and modulate the audio input signal input to the audio sigma-delta analog-to-digital converter based on the calibration signal to obtain an audio output signal; the input terminal of the audio sigma-delta analog-to-digital converter is also connected to an audio input circuit; the configuration of the digital-to-analog converter is adjusted to output a target calibration signal, wherein, after the sigma-delta modulator modulates the audio input signal based on the target calibration signal, the interference sound in the obtained audio output signal is within a preset frequency range; the preset frequency range is: the frequency range of sounds that are not audible to the human ear; or, if the audio sigma-delta analog-to-digital converter is connected to a filter, after the filter filters the interference sound within the preset frequency range, the amplitude or power attenuation value of the interference sound is less than a target threshold.

[0026] Thirdly, embodiments of this application provide a wearable device, including an audio sigma-delta analog-to-digital converter after interference suppression by the interference suppression method described in any of the first aspects. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 A schematic diagram of the structure of an audio sigma-delta analog-to-digital converter provided in one embodiment of this application;

[0029] Figure 2 A flowchart illustrating an interference sound suppression method provided in an embodiment of this application;

[0030] Figure 3 This is a schematic diagram of a sigma-delta modulator provided in one embodiment of this application.

[0031] Icons: Audio sigma-delta analog-to-digital converter 100; digital-to-analog converter 110; sigma-delta modulator 120; loop filter 121; gain circuit 122; quantizer 123; PGA 130; digital filter and downsampling module 140. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit this application.

[0033] First, embodiments of this application provide an audio sigma-delta analog-to-digital converter and a method for suppressing interference noise. The audio sigma-delta analog-to-digital converter uses this method to suppress interference noise. Accordingly, this interference noise suppression method can be applied to suppress interference noise in an audio sigma-delta analog-to-digital converter, and it can also be considered a calibration method for the audio sigma-delta analog-to-digital converter.

[0034] Please see Figure 1 , Figure 1 This is a schematic diagram of the structure of an audio sigma-delta analog-to-digital converter provided in one embodiment of this application.

[0035] In embodiments of this application, the audio sigma-delta analog-to-digital converter 100 includes a digital-to-analog converter 110 and a sigma-delta modulator 120. The output terminal of the digital-to-analog converter 110 is connected to the input terminal of the sigma-delta modulator 120; the sigma-delta modulator is used to receive the calibration signal output by the digital-to-analog converter 110, and modulate the audio input signal of the input audio sigma-delta analog-to-digital converter 100 based on the calibration signal to obtain an audio output signal.

[0036] In addition, the audio sigma-delta analog-to-digital converter 100 may also include a PGA (Programmable Gain Amplifier) ​​130 and a digital filter and downsampling module 140. The PGA 130 is used to receive the audio input signal and output it to the sigma-delta modulator 120, and the digital filter and downsampling module 140 is used to filter and downsample the audio output signal output by the sigma-delta modulator 120.

[0037] The specific structure of the audio sigma-delta analog-to-digital converter 100 can be found in existing technology and will not be elaborated here. The audio sigma-delta analog-to-digital converter 100 provided in this application uses the interference suppression method provided in this application to suppress interference; therefore, the specific structure of the audio sigma-delta analog-to-digital converter 100 should not be considered a limitation of this application.

[0038] In the embodiments of this application, the input terminal of the audio sigma-delta analog-to-digital converter 100 is connected to an audio input circuit. The audio input circuit is used to input audio signals to the audio sigma-delta analog-to-digital converter 100. Components such as microphones, audio acquisition circuits, and transmission circuits between the audio sigma-delta analog-to-digital converter 100 can all be considered as audio input circuits. Different audio input circuits exist depending on the application scenario of the audio sigma-delta analog-to-digital converter 100; therefore, no specific type of audio input circuit is limited here.

[0039] The audio input circuit has a certain noise floor, which may cause interference noise after the audio sigma-delta analog-to-digital converter 100 processes the audio input signal input to the audio input circuit. For example, ideally, when the voltage value of the received audio input signal is 0, the audio output signal of the audio sigma-delta analog-to-digital converter 100 after factory calibration should be 0. However, in reality, due to the influence of the noise floor of the audio input circuit, such as the audio acquisition circuit, microphone, and transmission circuit, the acquired audio input signal will introduce the noise floor of the circuit and microphone, thus making the value of the audio output signal not equal to 0, that is, interference noise exists.

[0040] In the embodiments of this application, the interference sounds are one or more single-frequency interferences. When the audio input signal of the audio sigma-delta analog-to-digital converter 100 is a DC component, it is then passed through a programmable gain amplifier and superimposed with the output of the digital-to-analog converter 110. After the DC component is removed from the output of the audio sigma-delta analog-to-digital converter 100, some single-frequency interferences with relatively large amplitudes will appear, and there may be multiple single-frequency interferences. Both the input of the audio sigma-delta analog-to-digital converter 100 and the output of the digital-to-analog converter 110 can be zero. Because analog circuits have circuit noise, the output of the audio sigma-delta analog-to-digital converter 100 will have a noise floor, present at all frequency points. However, the aforementioned single-frequency interferences will be higher than the noise floor, for example, 10dB, 15dB, or even more than 20dB higher. These single-frequency interferences are easily heard by the human ear and affect the user experience.

[0041] Therefore, in the embodiments of this application, an audio input signal with a signal value of 0 can be used to test and calibrate the audio sigma-delta analog-to-digital converter 100 to test whether there is interference in the audio output signal. If the audio output signal of the audio sigma-delta analog-to-digital converter 100 can be heard by the user when the audio input signal is 0, it indicates that there is interference that can be heard by the user. Therefore, interference can be suppressed when it exists.

[0042] Please see Figure 2 , Figure 2 A schematic diagram of an interference noise suppression method provided in an embodiment of this application is shown. The interference noise suppression method includes:

[0043] Adjust the configuration of the digital-to-analog converter so that the interference sounds in the audio output signal obtained after the sigma-delta modulator modulates the audio input signal based on the target calibration signal are within the preset frequency range.

[0044] In this embodiment, the target calibration signal is the calibration signal output by the digital-to-analog converter after the configuration is adjusted.

[0045] In the embodiments of this application, the preset frequency range is divided into at least two cases. The first case is the frequency range of sounds that are not audible to the human ear. The second case is that the preset frequency range satisfies the following condition: when the audio sigma-delta analog-to-digital converter is connected to the filter, after the filter filters the interference sounds within the preset frequency range, the amplitude or power of the interference sounds is attenuated to less than the target threshold.

[0046] The target threshold is related to the noise floor and can be used to characterize the amplitude or power of the noise floor. For example, the target threshold can be equal to the amplitude or power of the noise floor, or it can be 1 / 2, 1 / 3, etc., of the amplitude or power of the noise floor. After attenuation, the user will be unable to hear or will have difficulty hearing the interference sound. Here, the user's inability to hear or difficulty hearing the interference sound is a subjective feeling. In reality, different users may have different perception abilities of the same interference sound. Therefore, no specific value is limited for the target threshold.

[0047] In one embodiment, adjusting the configuration of the digital-to-analog converter (DAC) may involve adjusting the DAC configuration to a first configuration.

[0048] Since the sigma-delta modulator 120 can modulate the audio input signal based on the calibration signal to change the calibration values ​​such as voltage and frequency of the output audio signal, and the magnitude of the calibration value of the calibration signal affects the frequency of the audio output signal modulated by the sigma-delta modulator 120, when the audio input signal voltage is 0 and the output audio signal is interference, adjusting the configuration of the digital-to-analog converter 110 changes the calibration value of the calibration signal output by the digital-to-analog converter 110. This allows the sigma-delta modulator 120 to change the frequency range of the output interference, thereby suppressing the interference.

[0049] In the embodiments of this application, the first configuration is used to make the target calibration value of the target calibration signal greater than or equal to a first preset threshold. If the target calibration value of the target calibration signal is greater than or equal to the first preset threshold, the sigma-delta modulator 120 modulates the audio input signal based on the calibration signal, so that the resulting audio output signal can be within a first frequency range.

[0050] In this embodiment, the first frequency range is the frequency range of sounds that are not audible to the human ear. For example, the frequency range of sounds audible to the human ear is 20Hz to 20kHz. Accordingly, the first frequency range can be greater than 20kHz or less than 20Hz. Since sounds less than 20Hz are not easily modulated, the first frequency range can be greater than 20kHz. Accordingly, in some embodiments, when the calibration value of the calibration signal output by the digital-to-analog converter 110 is used to characterize the voltage value, when the voltage value is greater than 0.5mV, 1mV, etc., the frequency of the interference sound can be greater than 20kHz, and the calibration value of the calibration signal can be greater than or equal to 0.5mV, 1mV, etc.

[0051] By adjusting the configuration of the digital-to-analog converter 110, the frequency of the audio output signal is made to exceed the frequency range of sounds that can be heard by the human ear. As a result, the interference sound will not be heard by the human ear, thus achieving the suppression of interference sound for humans.

[0052] Some digital-to-analog converters 110 can directly control the voltage of the output signal. Therefore, in this embodiment, adjusting the configuration of the digital-to-analog converter 110 to the first configuration can directly adjust the calibration value range of the output signal so that the calibration value of the calibration signal output by the digital-to-analog converter 110 is greater than or equal to a first preset threshold. Some digital-to-analog converters 110 cannot directly adjust the signal value of the output signal. Therefore, in this embodiment, other configuration parameters of the digital-to-analog converter 110 can be adjusted to make the calibration value of the output calibration signal greater than or equal to the first preset threshold. Therefore, this application does not limit the specific method of adjusting the configuration of the digital-to-analog converter 110; it can be selected according to the function of the device used.

[0053] The output of the sigma-delta modulator 120 of the audio sigma-delta analog-to-digital converter 100 can be connected to the digital filter and downsampling module 140, as well as other circuits with filters. Whether it is the filter in the digital filter and downsampling module 140 or the filter in other circuits, the audio output signal can be filtered. Therefore, in one embodiment of this application, the output signal of the audio sigma-delta analog-to-digital converter 100 can be filtered to remove interference.

[0054] In one embodiment, if the output of the sigma-delta modulator is used to connect to a filter, adjusting the configuration of the digital-to-analog converter may further include: adjusting the configuration of the digital-to-analog converter to a second configuration, wherein the second configuration is used to make the target calibration value of the target calibration signal within a second preset threshold range.

[0055] In this embodiment, the sigma-delta modulator modulates the initial audio input signal based on the target calibration signal within a second preset threshold range. The interference in the resulting audio output signal satisfies the following condition: after the filter filters the interference within the preset frequency range, the amplitude or power of the interference is attenuated to less than the target threshold, where the target threshold represents the amplitude or power of the background noise.

[0056] In this embodiment, the output signal can be output to a filter for filtering, which will attenuate the interference sound in the output signal. If the amplitude or frequency of the attenuated interference sound is less than the amplitude or frequency of the noise floor, or even 0, then the interference sound will not be perceived / heard by the user, thus achieving interference sound suppression.

[0057] Since the filter has different attenuation effects on different frequencies of sound, in this embodiment, the magnitude of the interference sound can be determined in advance. Then, based on the magnitude of the interference sound, the frequency of the interference sound that the filter will attenuate to less than the target threshold can be determined. Finally, the target calibration value of the target calibration signal output by the digital-to-analog converter is adjusted so that the frequency of the interference sound modulated by the target calibration signal can have sufficient attenuation in the filter, so that the attenuation value by the filter is less than the target threshold.

[0058] In other embodiments of this application, after acquiring an audio input signal with a voltage value of 0, the configuration of the digital-to-analog converter 110 can be adjusted to a third configuration. The third configuration is used to make the target calibration value of the target calibration signal within a second preset threshold range. If the target calibration value of the target calibration signal is within the second preset threshold range, the sigma-delta modulator 120 modulates the audio input signal based on the calibration signal so that the resulting audio output signal is within a second frequency range. The second frequency range is the frequency range of the filter.

[0059] When the audio input signal is 0, the audio output signal is interference. Adjusting the interference to the frequency range of the filter can filter out the interference, thus suppressing the interference.

[0060] For example, if the filtering range of the digital filter in the audio sigma-delta analog-to-digital converter 100 or the filter connected to the audio sigma-delta analog-to-digital converter 100 is 10kHz-15kHz, then the configuration of the digital-to-analog converter 110 can be adjusted to a second configuration, such that the sigma-delta modulator 120 modulates the audio input signal with a signal value of 0 based on the calibration signal output by the digital-to-analog converter 110, so that the resulting audio output signal is within the range of 10kHz-15kHz.

[0061] In the embodiments of this application, the first configuration, the second configuration, and the third configuration can be used selectively. The first configuration has better versatility and can be used in different circuits, while the second configuration can filter out interference sounds, avoiding the potential impact of interference sounds in subsequent use. Accordingly, the audio sigma-delta analog-to-digital converter 100 provided in this application has at least one of the first and second configurations.

[0062] In the embodiments of this application, the resolution of the digital-to-analog converter 110 is greater than or equal to a preset number of bits; the preset number of bits digital-to-analog converter 110 allows the output of a calibration signal with a calibration value greater than or equal to a first preset threshold, and / or, the preset number of bits digital-to-analog converter 110 allows the output of a calibration signal with a calibration value within a second preset threshold range.

[0063] In analog circuits, the changes in parameters are not continuous, but rather occur at multiple consecutive points, each corresponding to a value. For example, the calibration signal output by the digital-to-analog converter 110 can be 0, 0.1, 0.2, 0.3, etc. When the accuracy of the digital-to-analog converter 110 is insufficient, the calibration signal increases by 0.1 at each level, and the calibration signal cannot be equal to 0.05, 0.15, 0.25, etc. However, when the accuracy of the digital-to-analog converter 110 is high, the calibration signal can increase by 0.02 at each level, and the calibration signal can even be equal to 0.02, 0.04, 0.06, 0.08, 0.10, 0.12, 0.14, 0.22, etc.

[0064] If the voltage value of the calibration signal needs to be greater than or equal to a first preset threshold, or within a second threshold range, then the accuracy of the calibration signal needs to meet certain requirements. In the embodiments of this application, the resolution of the digital-to-analog converter 110 used needs to be greater than or equal to a preset number of bits, wherein the preset number of bits digital-to-analog converter 110 allows the output calibration signal with a calibration value greater than or equal to the first preset threshold, and / or, the preset number of bits digital-to-analog converter 110 allows the output calibration signal with a calibration value within the second preset threshold range.

[0065] In the above embodiments, without considering the connected circuitry and microphone noise floor, the audio sigma-delta analog-to-digital converter 100 used needs to output an audio signal of 0 when the audio input signal is 0. This audio sigma-delta analog-to-digital converter 100 is typically a factory-calibrated product. Factory calibration refers to the initial calibration of the audio sigma-delta analog-to-digital converter 100 after its manufacture, ensuring that the audio output signal is also 0 when the audio input signal is 0. Factory calibration can be achieved by adjusting the voltage value of the calibration signal output by the digital-to-analog converter 110. For the factory-calibrated audio sigma-delta analog-to-digital converter 100, interference noise suppression can be directly applied.

[0066] If the audio sigma-delta analog-to-digital converter 100 is not initially calibrated, when the audio input signal is 0, even without the influence of circuit and microphone background noise, the audio output signal of the audio sigma-delta analog-to-digital converter 100 may not be 0. Even after adjusting the configuration of the digital-to-analog converter 110 to the first configuration or the second configuration, it may not be possible to make the calibration signal meet the requirement that the frequency of the audio output signal is in the first frequency range or the second frequency range. Therefore, in the embodiments of this application, a second preset value of the digital-to-analog converter 110 can be obtained before adjusting the configuration of the digital-to-analog converter 110 to the first configuration based on the audio input signal. When adjusting the configuration of the digital-to-analog converter 110 to the first configuration based on the audio input signal, the configuration of the digital-to-analog converter 110 is adjusted to increase the first preset value based on the second preset value, so that the target calibration value of the target calibration signal is greater than or equal to the first preset threshold.

[0067] In this embodiment, the second preset value is the value of the calibration signal output by the digital-to-analog converter 110 when the voltage values ​​of both the input and output audio signals are 0 during the initial calibration process of the audio sigma-delta analog-to-digital converter 100. Both the second and first preset values ​​can be voltage values.

[0068] Initial calibration refers to the calibration of the audio sigma-delta analog-to-digital converter 100 without connecting any circuitry or microphone. At this time, due to the absence of background noise from the circuitry and microphone, only the noise of the audio sigma-delta analog-to-digital converter 100 itself affects the audio output signal. In this case, the configuration of the digital-to-analog converter 110 within the audio sigma-delta analog-to-digital converter 100 can be adjusted so that the audio output signal from the audio sigma-delta analog-to-digital converter 100 is 0. The value of the calibration signal output by the digital-to-analog converter 110 at this time is recorded as the second preset value.

[0069] Without the influence of circuit and microphone background noise, enabling the digital-to-analog converter 110 to output a second preset value ensures that the audio sigma-delta analog-to-digital converter 100 outputs a zero audio signal even with an audio input signal. Further, to eliminate interference from circuit and microphone background noise, the configuration of the digital-to-analog converter 110 can be adjusted by adding a first preset value to the second preset value, ensuring that the voltage value of the calibration signal is greater than or equal to a first preset threshold or within the range of the second threshold.

[0070] Using the above method, even if the audio sigma-delta analog-to-digital converter 100 has not been initially calibrated, it is possible to calibrate the audio sigma-delta analog-to-digital converter 100 for interference noise suppression.

[0071] The audio sigma-delta analog-to-digital converter 100 is used for analog-to-digital conversion and should not cause voltage changes in the audio input signal. However, in actual use, because the sigma-delta modulator 120 modulates both the audio digital-to-analog converter 110 and the non-zero audio input signal, the voltage of the audio output signal may become mismatched with the audio input signal. Instead, the voltage of the calibration signal may be added to the original audio output signal voltage, affecting the accuracy of the audio output signal.

[0072] Therefore, in one embodiment of this application, the audio output signal modulated by the sigma-delta modulator 120 can be reduced by the sigma-delta modulator 120 and output by the quantizer; the quantizer reduces the audio output signal by a third preset value; the third voltage value matches the value of the target calibration signal.

[0073] In one embodiment of this application, a quantizer can be connected in or after the sigma-delta modulator 120 so that the sigma-delta modulator 120 outputs the audio output signal through the quantizer. See also... Figure 3 , Figure 3 This is a schematic diagram of a sigma-delta modulator 120 provided in an embodiment of this application. The sigma-delta modulator 120 includes a loop filter 121, a gain circuit 122, and a quantizer 123 connected in sequence. The quantizer 123 is used to output an audio output signal, and "+" indicates input superposition.

[0074] For the sigma-delta modulator 120, there are no restrictions here. The type of sigma-delta modulator 120 can be a first-order 1-bit output, a second-order 1-bit output, a second-order 3-bit output, a third-order 1-bit output, a third-order 3-bit output, a fifth-order multi-bit output, etc.

[0075] In this embodiment, the quantizer 123 subtracts a third preset value from the received audio output signal. The third preset value matches the calibration value of the calibration signal. The signal received by the quantizer 123 is also the audio output signal. Thus, the digital-to-analog converter 110 and the quantizer 123 cancel out the voltage of the audio output signal, effectively reducing the impact of the audio sigma-delta analog-to-digital converter 100 on the accuracy of the audio output signal.

[0076] Ideally, the third preset value configured by the quantizer 123 is equal to the voltage value of the calibration signal, thereby effectively canceling the influence of the calibration signal voltage value on the audio output signal. However, due to process variations, analog circuits have various non-ideal characteristics, such as deviations in components including resistors, capacitors, and inductors. For a specific actual chip, the output value of its digital-to-analog converter 110 will deviate from the ideal value, and the output value of the digital-to-analog converter 110 of this actual chip can be calibrated.

[0077] Therefore, in the embodiments of this application, the third preset value can be: the calibration value of the audio output signal when the signal value of the audio input signal is 0 and the configuration of the digital-to-analog converter 110 is the first configuration, the third configuration, or the third configuration.

[0078] This method configures a third preset value based on the actual audio output signal output by the audio sigma-delta analog-to-digital converter 100. The actual output audio signal takes into account the influence of process deviations, which can accurately offset the voltage influence of the calibration signal on the audio output signal and improve the accuracy of the audio output signal.

[0079] In one embodiment of this application, interference suppression may be performed on the audio sigma-delta analog-to-digital converter 100 using other calibration equipment. In this embodiment, the calibration equipment vectorizer 123 may send a signal to synchronously change the third preset value configured by the quantizer 123 in the event of a configuration change in the analog-to-digital converter. In other embodiments, the analog-to-digital converter vectorizer 123 may send a signal to cause the quantizer 123 to change the third preset value according to the received signal in the event of a configuration change in the analog-to-digital converter; this is not limited to this embodiment.

[0080] In the embodiments of this application, since digital-to-analog conversion is involved, some signals used are digital signals, such as the final audio output signal of the audio sigma-delta analog-to-digital converter and the input signal of the digital-to-analog converter, while other signals are analog signals, such as the target calibration value of the target calibration signal. Regardless of whether the signals are digital or analog, they can all characterize the same electrical parameters, for example, voltage values.

[0081] In some embodiments of this application, the target calibration value of the target calibration signal is a voltage value. In the first configuration, there may be multiple voltage values ​​of the calibration signal output by the digital-to-analog converter 110 that are greater than or equal to a first preset threshold. Multiple voltage values ​​constitute a preset sequence. Each voltage value may correspond to a sub-configuration of the digital-to-analog converter 110. That is, the first configuration includes multiple voltage values ​​and their respective sub-configurations.

[0082] Similarly, in the second configuration, the voltage value of the calibration signal output by the digital-to-analog converter 110 within the second threshold range can be multiple, and the multiple voltage values ​​constitute a preset sequence. Each voltage value can correspond to a sub-configuration of the digital-to-analog converter 110. That is, the second configuration includes multiple voltage values ​​and their respective sub-configurations.

[0083] After adjusting the configuration of the digital-to-analog converter 110 to the first configuration, the second configuration, or the third configuration based on the audio input signal, the digital-to-analog converter 110 can also be configured to: randomly or sequentially select a voltage value from a preset sequence at preset time intervals as the target preset voltage value, and adjust the configuration of the digital-to-analog converter 110 to the configuration of the digital-to-analog converter 110 corresponding to the target preset voltage value.

[0084] In this embodiment, each voltage value in the preset sequence may be calibrated in the manner described above. Randomization can be achieved using existing methods, such as PRBS (Pseudo-Random Binary Sequence).

[0085] Because the operating environment and conditions of the audio sigma-delta analog-to-digital converter 100 and the connected circuit microphone may change, the background noise may change. Since this change is uncertain, multiple different voltage values ​​that meet the conditions can be set, and the voltage value of the calibration signal output by the digital-to-analog converter 110 can be continuously changed. This can reduce the impact of changes in the operating environment on the interference noise suppression effect.

[0086] Similarly, when the voltage value of the calibration signal changes, the digital-to-analog converter 110 can send a synchronization signal to the quantizer 123 after the sigma-delta modulator 120, so that the third preset value configured in the quantizer is synchronized with or corresponds to the voltage value of the calibration signal.

[0087] The audio sigma-delta analog-to-digital converter 100 requires adjustment of its range and sampling rate, or audio sigma-delta analog-to-digital converter 100 with the same structure needs to be configured with different ranges and sampling rates. Increasing the sampling rate can improve the signal-to-noise ratio of the audio sigma-delta analog-to-digital converter 100, while decreasing the range can improve the accuracy of the audio sigma-delta analog-to-digital converter 100. This causes changes in the dynamic input variation range of the audio sigma-delta analog-to-digital converter 100, which may result in interference sounds not being modulated to the first frequency range or the second frequency range under the same calibration signal value, thus failing to effectively suppress interference sounds.

[0088] Therefore, in one embodiment, after adjusting the configuration of the digital-to-analog converter 110 to a first configuration, a second configuration, or a third configuration based on the audio input signal, the sampling rate change of the audio sigma-delta analog-to-digital converter 100 can also be obtained; the configuration of the digital-to-analog converter 110 is adjusted again based on the sampling rate change, so that the sigma-delta modulator 120 modulates the audio input signal based on the calibration signal output by the digital-to-analog converter 110 after the configuration is adjusted, and the resulting audio output signal is within a preset frequency range, wherein the preset frequency range is the aforementioned frequency range of non-human audible sounds; or, if the audio sigma-delta analog-to-digital converter is connected to a filter, after the filter filters the interference sounds within the preset frequency range, the amplitude or power of the interference sounds is attenuated to less than a target threshold.

[0089] In embodiments of this application, the change in the sampling rate of the audio sigma-delta analog-to-digital converter 100 is inversely proportional to the change in the target calibration value of the target calibration signal after the configuration of the digital-to-analog converter 110 is adjusted. For example, if the sampling rate is increased by R1 times, the target calibration value of the target calibration signal is reduced to 1 / R1 of the original value.

[0090] By adjusting the configuration of the digital-to-analog converter 110, the target calibration value of the target calibration signal output by the digital-to-analog converter 110 can still ensure that the frequency of interference sounds in the audio output signal is within the first frequency range or the second frequency range after the sampling rate changes. This can effectively reduce the impact of sampling rate changes on the interference sound suppression effect.

[0091] Similarly, after adjusting the configuration of the digital-to-analog converter 110 to the first, second, or third configuration based on the audio input signal, the range change of the audio sigma-delta analog-to-digital converter 100 can also be obtained; based on the range change, the configuration of the digital-to-analog converter 110 is further adjusted so that the sigma-delta modulator modulates the audio input signal based on the calibration signal output by the digital-to-analog converter 110 after the configuration is adjusted, and the resulting audio output signal is within the preset frequency range.

[0092] In this embodiment, the change in the range of the audio sigma-delta analog-to-digital converter 100 is proportional to the change in the target calibration value of the target calibration signal after the configuration adjustment of the digital-to-analog converter 110. For example, if the range is reduced to 1 / R2 of the original, the target calibration value of the target calibration signal after the configuration adjustment will be reduced to 1 / R2 of the original.

[0093] By adjusting the configuration of the digital-to-analog converter 110, the target calibration value of the target calibration signal output by the digital-to-analog converter 110 can still ensure that the frequency of interference sounds in the audio output signal is within the preset frequency range after the range changes, which can effectively reduce the impact of range changes on the interference sound suppression effect.

[0094] The interference suppression method and audio sigma-delta analog-to-digital converter 100 provided in this application can suppress interference by configuring the digital-to-analog converter 110 with a first configuration so that the interference output of the audio sigma-delta analog-to-digital converter 100 cannot be heard, or configuring the digital-to-analog converter with a second configuration so that the interference output of the audio sigma-delta analog-to-digital converter 100 is attenuated by a subsequent filter and thus cannot be perceived by the human ear.

[0095] Based on the same inventive concept, this application also provides a wearable device, which includes the audio sigma-delta analog-to-digital converter 100 provided in the foregoing embodiments or the audio sigma-delta analog-to-digital converter 100 calibrated by the interference noise suppression method provided in any of the foregoing embodiments.

[0096] In this embodiment, the wearable device can be an earphone, a smartwatch, a smart bracelet, or smart glasses. The earphone can be one of the following: an in-ear earphone, a semi-in-ear earphone, an open-back earphone, or a headphone; there is no limitation on this.

[0097] In the embodiments provided in this application, it should be understood that the disclosed methods can also be implemented in other ways. The functional modules in the various embodiments of this application can be integrated together to form an independent part, or each module can exist independently, or two or more modules can be integrated to form an independent part.

[0098] The above embodiments can be freely combined without conflict, and the resulting embodiments are covered within the protection scope of this application.

[0099] The above detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0100] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0101] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the term "connection" should be interpreted broadly. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0102] The above description is merely an embodiment of this application and is not intended to limit the scope of protection of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A method for suppressing interference sounds, characterized in that, This is applied to suppress interference noise in an audio sigma-delta analog-to-digital converter, which includes a digital-to-analog converter and a sigma-delta modulator. The output terminal of the digital-to-analog converter is connected to the input terminal of the sigma-delta modulator; the sigma-delta modulator is used to receive the calibration signal output by the digital-to-analog converter, and modulate the audio input signal input to the audio sigma-delta analog-to-digital converter based on the calibration signal to obtain the audio output signal; The input terminal of the audio sigma-delta analog-to-digital converter is connected to the audio input circuit; The interference noise suppression method includes: The configuration of the digital-to-analog converter is adjusted so that the interference sound in the audio output signal obtained after the sigma-delta modulator modulates the audio input signal based on the target calibration signal is within a preset frequency range; the target calibration signal is the calibration signal output by the digital-to-analog converter after the configuration is adjusted. The preset frequency range is the frequency range of sounds that are not audible to the human ear; or, if the audio sigma-delta analog-to-digital converter is connected to a filter, after the filter filters the interference sounds within the preset frequency range, the amplitude or power of the interference sounds is attenuated to less than the target threshold.

2. The interference suppression method according to claim 1, characterized in that, The adjustment of the configuration of the digital-to-analog converter includes: The configuration of the digital-to-analog converter is adjusted to a first configuration, which is used to make the target calibration value of the output target calibration signal greater than or equal to a first preset threshold. If an initial audio input signal with an amplitude of 0 is obtained, the sigma-delta modulator modulates the initial audio input signal based on a target calibration signal that is greater than or equal to the first preset threshold, and the interference sound in the obtained audio output signal is within the frequency range of the non-human audible sound.

3. The interference suppression method according to claim 2, characterized in that, The resolution of the digital-to-analog converter is greater than or equal to a preset resolution; the preset bit digital-to-analog converter allows the output calibration signal with a calibration value greater than or equal to the first preset threshold.

4. The interference suppression method according to claim 2, characterized in that, Before adjusting the configuration of the digital-to-analog converter to the first configuration, the method further includes: Obtain a second preset value for the digital-to-analog converter; the second preset value is the value of the calibration signal output by the digital-to-analog converter when both the input audio signal and the output audio signal are 0 during the initial calibration process of the audio sigma-delta analog-to-digital converter. The step of adjusting the configuration of the digital-to-analog converter to a first configuration based on the audio input signal includes: The configuration of the digital-to-analog converter is adjusted to increase the first preset value based on the second preset value, so that the target calibration value of the target calibration signal is greater than or equal to the first preset threshold.

5. The interference noise suppression method according to claim 2, characterized in that, After adjusting the configuration of the digital-to-analog converter to the first configuration, the method further includes: Obtain the sampling rate change of the audio sigma-delta analog-to-digital converter; The configuration of the digital-to-analog converter is readjusted based on the sampling rate change, so that the sigma-delta modulator modulates the audio input signal based on the target calibration signal output by the readjusted digital-to-analog converter, and the interference sound in the resulting audio output signal is within the frequency range of non-human audible sounds. The change in the sampling rate of the audio sigma-delta analog-to-digital converter is inversely proportional to the change in the target calibration value of the target calibration signal after the configuration of the digital-to-analog converter is adjusted.

6. The interference noise suppression method according to claim 2, characterized in that, After adjusting the configuration of the digital-to-analog converter to the first configuration, the method further includes: Obtain the range change of the audio sigma-delta analog-to-digital converter; The configuration of the digital-to-analog converter is readjusted based on the range change, so that the sigma-delta modulator modulates the audio input signal based on the target calibration signal output by the readjusted digital-to-analog converter, and the interference sound in the resulting audio output signal is within the frequency range of the non-human audible sound. The range change of the audio sigma-delta analog-to-digital converter is proportional to the change in the target calibration value of the target calibration signal after the configuration of the digital-to-analog converter is adjusted.

7. The interference noise suppression method according to claims 2-6, characterized in that, The sigma-delta modulator outputs the audio output signal through a quantizer; the quantizer is used to subtract a third preset value from the audio output signal; the third preset value matches the value of the target calibration signal.

8. The interference suppression method according to claim 7, characterized in that, The third preset value is the signal value of the audio output signal when the audio input signal is 0 and the digital-to-analog converter is configured in the first configuration.

9. The interference suppression method according to claim 8, characterized in that, The target calibration value of the target calibration signal is a voltage value. The first configuration includes a preset sequence of multiple voltage values ​​and a sub-configuration of a digital-to-analog converter corresponding to each voltage value. Each voltage value in the preset sequence is greater than the first preset threshold. After adjusting the configuration of the digital-to-analog converter to the first configuration, the method further includes: The digital-to-analog converter is configured to: randomly or sequentially select a voltage value from the preset sequence at preset time intervals as the target preset voltage value, and adjust the configuration of the digital-to-analog converter to the configuration of the digital-to-analog converter corresponding to the target preset voltage value.

10. The interference suppression method according to claim 1, characterized in that, If the output of the sigma-delta modulator is used to connect to a filter; The adjustment of the configuration of the digital-to-analog converter includes: The configuration of the digital-to-analog converter is adjusted to a second configuration, which is used to make the target calibration value of the target calibration signal within a second preset threshold range; The sigma-delta modulator modulates the initial audio input signal based on a target calibration signal within the second preset threshold range, and the interference in the resulting audio output signal satisfies the following: after the filter filters the interference within the preset frequency range, the amplitude or power of the interference is attenuated to less than the target threshold.

11. An audio sigma-delta analog-to-digital converter, characterized in that, include: Digital-to-analog converters and sigma-delta modulators; The output of the digital-to-analog converter is connected to the input of the sigma-delta modulator. The sigma-delta modulator is used to receive the calibration signal output by the digital-to-analog converter, and modulate the audio input signal input to the audio sigma-delta analog-to-digital converter based on the calibration signal to obtain an audio output signal; the input terminal of the audio sigma-delta analog-to-digital converter is also connected to an audio input circuit. The configuration of the digital-to-analog converter is adjusted to output a target calibration signal, wherein the interference sound in the audio output signal obtained after the sigma-delta modulator modulates the audio input signal based on the target calibration signal is within a preset frequency range. The preset frequency range is: the frequency range of sounds that are not audible to the human ear; or, if the audio sigma-delta analog-to-digital converter is connected to the filter, after the filter filters the interference sounds in the preset frequency range, the amplitude or power attenuation value of the interference sounds is less than the target threshold.

12. A wearable device, characterized in that, Includes an audio sigma-delta analog-to-digital converter after interference suppression by the interference suppression method as described in any one of claims 1-10.

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