CN115550785A - Earphone amplifier for calibrating frequency deviation of sound source - Google Patents

Abstract

The invention relates to an earphone amplifier for calibrating the frequency deviation of a sound source, which uses sampling rate information to send a mode controller to output frequency switching control parameters to an LUT (look-up table), controls the mode of a sliding mode filter to be rapid frequency switching, sends filtered control data to a low-noise DAC (digital-to-analog converter), and outputs the control data to a VCO (voltage controlled oscillator) after passing through an analog loop filter; the VCO output is sent to a synchronous frequency divider, and then sent to a frequency measurer consisting of a counting window generator and a counter to complete frequency measurement. The frequency measurement is fed to the LUT and to the mode controller, which controls the loop. The audio frequency of 20kHz is superposed in the input sound source, the superposed audio frequency is loaded and processed along with the original audio frequency, the processed audio frequency is detected by the detection module after passing through the amplifier, and the frequency deviation, the broadening and the loudness change brought in the processing process can be fully detected, so that the working state can be displayed in the display module in real time, and a user can conveniently know the working state of the equipment at any time.

Description

Earphone amplifier for calibrating frequency deviation of sound source

Technical Field

The invention relates to the field of earphone amplifiers, in particular to an earphone amplifier for calibrating frequency deviation of a sound source.

Background

In actual equipment, a sound source often has frequency deviation due to multiple copying, compression and the like, and particularly, a clock has offset which is not accumulated along an actual clock with time and is advanced or lagged in time relative to an ideal clock. In practice it is often desirable that the time a periodic waveform, in particular a clock, crosses a certain threshold is very accurate.

Application number CN201310287918.4 discloses a method and apparatus for processing the deviation, specifically comprising step 1: receiving an analog signal z (t); step 2: providing a clock signal h (t) to an analog-to-digital conversion module, and simultaneously adding a product of the clock signal h (t) and a single-tone signal m (t) as a reference signal q (t) to an analog signal z (t) to obtain a composite signal r (t); and step 3: the analog-to-digital conversion module performs analog-to-digital conversion on the composite signal r (t) to obtain two paths of completely same composite digital signals rjit (n); and 4, step 4: a step 5 of obtaining a clock jitter sequence after performing jitter sequence estimation on one path of the composite digital signal rjit (n): and performing clock jitter elimination on the other path of the composite digital signal rjit (n) by using a clock jitter sequence, thereby obtaining a pure digital signal y (n) with clock jitter eliminated.

Although the deviation can be reduced to a certain extent, on one hand, the headphone amplifier is not suitable for processing audio playing, and on the other hand, in the audio playing, a user often wants to know the working state of the device to adjust various playing parameters at any time, so that a headphone amplifier for calibrating the frequency deviation of the sound source is needed.

Disclosure of Invention

In order to solve the above problems, the present invention provides an earphone amplifier for calibrating the frequency deviation of a sound source, which includes an input interface, an output interface, a calibration module, and an amplification module;

the device also comprises a sound source module, a superposition module, a detection module and a display module;

the sound source module sends digital audio data to the superposition module, high-frequency tracing audio is superposed in the superposition module, and the superposed audio data is sent to the input interface to enter the calibration module;

the calibration module is arranged between the input interface and the amplification module and is used for calibrating the frequency deviation of the sound source;

the amplifying module is connected with an output interface at the back, and the output interface is connected with a sound playing device at the back;

the amplifying module is further connected with a detection module, the detection module detects and extracts high-frequency tracing audio from the audio amplified by the amplifying module, the high-frequency tracing audio is analyzed, and an analysis result is displayed on the display module.

The superposition module is provided with a 20MHz high-precision clock, and after acquiring the audio data sent by the sound source module, the superposition module superposes the audio data of the fixed frequency F and the audio data sent by the sound source; the value range of F is 20kHz-24kHz.

The specific mode of audio superposition is one of the following two modes:

the first method is as follows: the superposition module acquires a clock path signal of the digital audio sent by the sound source module and generates digital audio data with fixed frequency F according to the clock path signal of the sound source;

directly adding the generated digital audio data with the fixed frequency F and the digital audio format data sent by the sound source module on a data track to obtain superposed mixed audio data, wherein the mixed audio data comprises the audio with the fixed frequency F;

the second method comprises the following steps: and an ADC (analog-to-digital converter) module and a DAC (digital-to-analog converter) module are arranged in the superposition module, digital audio sent by the sound source module is subjected to digital-to-analog conversion, then the audio with fixed frequency F pre-stored in the superposition module is directly superposed with the audio of the sound source module to obtain mixed audio of analog signals, and then the mixed audio is subjected to analog-to-digital conversion and output.

The calibration module comprises a reference clock, a sampling rate input, an I2S input, a cache module, a frequency synthesis module and an output module;

the reference module and the sampling rate input are both connected to the frequency synthesis module, and the frequency synthesis module performs local clock frequency locking on the sampling rate and performs local clock frequency detection; calculating the difference value between the sampling rate and the I2S input clock and the local clock, and further setting the direction and the depth of a cache sequence according to the difference value to realize the correction of clock deviation;

the frequency synthesis module comprises a mode controller 1, a counting window generator 2, a counter 3, a synchronous frequency divider 4, an LUT5, a subtracter 6, an FIR filter 7, a sliding mode filter 8, a low-noise DAC9, an analog loop filter 10 and a broadband VCO11;

the reference module outputs a 10MHz high-precision reference clock to the counting window generator 2;

the sampling rate information is sent to a mode controller 1 so as to output frequency switching control parameters to an LUT5, meanwhile, the mode of a sliding mode filter 8 is controlled to be fast frequency switching, and the filtered control data is sent to a low-noise DAC9 and is output to a VCO11 after passing through an analog loop filter 10;

the VCO output is sent to a synchronous frequency divider 4, and then sent to a frequency measurer consisting of a counting window generator 2 and a counter 3 to complete frequency measurement; the frequency measurement result is sent to the LUT5 and the mode controller 1, and the mode controller 1 controls the loop;

inputting I2S data and sending the data into a large-capacity cache 15, acquiring a difference value between sampling rate information and an I2S input clock by the mode controller 1 through an LUT5 unit, and setting a cache sequence direction and a cache depth of an FIFO (first in first out) through the difference value;

the maximum depth of the large-capacity cache 15 can ensure that the CD disk is played for 74 minutes without leakage; meanwhile, a silence detection module is arranged, wherein the silence detection is a protection mechanism, and a large-capacity cache 15 is reset in a silence segment; by resetting the mass buffer 15, a continuous and stable operation of the system can be ensured.

The detection module acquires an analog signal from the output of the amplification module, the analog signal is a copy of the output signal of the amplification module, and the analog signal is digitized to obtain detection data; the detection module performs time division on the acquired detection data; namely, generating a small segment of fragment audio data at fixed time intervals T; performing frequency domain conversion on the generated fragment audio data to obtain a frequency spectrum of the fragment audio data;

the detection module reserves data with the center frequency of F and the width of W in the fragment audio data, and deletes the rest of the data to obtain tracing fragment audio data; processing the audio data of the tracing fragments to obtain the central frequency F _n And a full width at half maximum W _n And central frequency intensity H _n (ii) a Where n is the number of the fragment audio data, i.e., the nth trace fragment audio data.

Centering frequency F along time _n And half width W _n And central frequency intensity H _n Three curves are generated, the abscissa is n, and the ordinate is the central frequency F _n And half width W _n And central frequency intensity H _n The value of (c).

Detection module for detecting center frequency F _n And half width W _n And central frequency intensity H _n Is not within a threshold range, the threshold including an upper threshold and a lower threshold;

the detection modules respectively calculate the center frequencies F exceeding the threshold values _n And half width W _n Or intensity of center frequency H _n The duration of (d);

displaying the central frequency F on the ordinate on the display module _n And half width W _n And central frequency intensity H _n Shows the center frequency F exceeding the threshold _n And half width W _n Or intensity of center frequency H _n And marks a curve that is not within the threshold range to indicate the operating state of the calibration module.

The invention has the beneficial effects that:

the invention superposes 20kHz audio frequency in an input sound source, and the frequency is selected because the upper limit of the response frequency of a common earphone or a sound box is about 20kHz, so that the audio loudspeaker of 20kHz can not generate response basically; meanwhile, the resolution limit of the human ear is not enough to be 20kHz, so that the human ear can not hear the sound of 20kHz even if the sound is played; in addition, the sampling rate of the general audio is 44.1kHz, 48kHz and 96kHz, so that the audio of 20kHz can be processed in the circuit.

The superposed audio is loaded and then processed along with the original audio, the processed audio is detected by the detection module after passing through the amplifier, and the frequency deviation, broadening and loudness change brought in the processing process can be fully detected, so that the working state can be displayed in the display module in real time, and a user can conveniently know the working state of the equipment at any time.

The invention uses the sampling rate information to send the frequency switching control parameter output by the mode controller to the LUT, and controls the mode of the sliding mode filter to be rapid frequency switching, the filtered control data is sent to the low noise DAC, and is output to the VCO after passing through the analog loop filter; the VCO output is sent to a synchronous frequency divider, and then sent to a frequency measurer consisting of a counting window generator and a counter to complete frequency measurement. The frequency measurement is fed to the LUT and to the mode controller, which controls the loop. The input I2S data is sent into a large-capacity cache, the mode controller obtains the difference value between the local frequency clock frequency and the I2S input clock through an LUT unit, and the cache sequence direction and the cache depth of the FIFO are set through the difference value. The maximum depth of the FIFO ensures that the 74 minutes CD is played without leakage. Silence detection is a protection mechanism that resets the FIFO in the silence segment. By resetting the FIFO, a continuous stable operation of the system can be ensured.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without inventive exercise.

FIG. 1 is a schematic diagram of the overall architecture of the present invention;

FIG. 2 is a schematic diagram of a calibration module connection structure according to the present invention;

FIG. 3 is a schematic diagram of the circuit structure of the present invention.

Detailed Description

Example 1:

referring to fig. 1, the present invention provides an earphone amplifier for calibrating frequency deviation of a sound source, including an input interface, an output interface, a calibration module, and an amplification module;

the device also comprises a sound source module, a superposition module, a detection module and a display module;

the sound source module sends digital audio data to the superposition module, high-frequency tracing audio is superposed in the superposition module, and the superposed audio data is sent to the input interface and enters the calibration module;

the calibration module is arranged between the input interface and the amplification module and is used for calibrating the frequency deviation of the sound source;

the amplifying module is connected with an output interface at the back, and the output interface is connected with a sound playing device at the back;

the amplifying module is further connected with a detection module, the detection module detects and extracts high-frequency tracing audio from the audio amplified by the amplifying module, the high-frequency tracing audio is analyzed, and an analysis result is displayed on the display module.

The superposition module is provided with a 20MHz high-precision clock, and after acquiring the audio data sent by the sound source module, the superposition module superposes the audio data with fixed frequency F and the audio data sent by the sound source; the value range of F is 20kHz-24kHz.

The specific mode of audio superposition is one of the following two modes:

the first method is as follows: the superposition module acquires a clock path signal of the digital audio sent by the sound source module and generates digital audio data with fixed frequency F according to the clock path signal of the sound source;

directly adding the generated digital audio data with the fixed frequency F and the digital audio format data sent by the sound source module on a data track to obtain superposed mixed audio data, wherein the mixed audio data comprises the audio with the fixed frequency F;

the second method comprises the following steps: and an ADC (analog-to-digital converter) module and a DAC (digital-to-analog converter) module are arranged in the superposition module, digital audio sent by the sound source module is subjected to digital-to-analog conversion, then the audio with fixed frequency F pre-stored in the superposition module is directly superposed with the audio of the sound source module to obtain mixed audio of analog signals, and then the mixed audio is subjected to analog-to-digital conversion and output.

The calibration module comprises a reference clock, a sampling rate input, an I2S input, a cache module, a frequency synthesis module and an output module;

the reference module and the sampling rate input are both connected to the frequency synthesis module, and the frequency synthesis module performs local clock frequency locking on the sampling rate and performs local clock frequency detection; calculating the difference value between the sampling rate and the I2S input clock and the local clock, and further setting the direction and the depth of a cache sequence according to the difference value to realize the correction of clock deviation;

the frequency synthesis module comprises a mode controller 1, a counting window generator 2, a counter 3, a synchronous frequency divider 4, an LUT5, a subtracter 6, an FIR filter 7, a sliding mode filter 8, a low noise DAC9, an analog loop filter 10 and a broadband VCO11;

the reference module outputs a 10MHz high-precision reference clock to the counting window generator 2;

the sampling rate information is sent to a mode controller 1 so as to output frequency switching control parameters to an LUT5, meanwhile, the mode of a sliding mode filter 8 is controlled to be fast frequency switching, and the filtered control data is sent to a low-noise DAC9 and is output to a VCO11 after passing through an analog loop filter 10;

the VCO output is sent to a synchronous frequency divider 4, and then sent to a frequency measurer consisting of a counting window generator 2 and a counter 3 to complete frequency measurement; the frequency measurement result is sent to the LUT5 and the mode controller 1, and the mode controller 1 controls the loop;

inputting I2S data and sending the data into a large-capacity cache 15, acquiring a difference value between sampling rate information and an I2S input clock by the mode controller 1 through an LUT5 unit, and setting a cache sequence direction and a cache depth of an FIFO (first in first out) through the difference value;

the maximum depth of the large-capacity cache 15 can ensure that the CD disk is played for 74 minutes without leakage; meanwhile, a silence detection module is arranged, wherein the silence detection is a protection mechanism, and a large-capacity cache 15 is reset in a silence segment; by resetting the mass buffer 15, a continuous and stable operation of the system can be ensured.

The detection module acquires an analog signal from the output of the amplification module, the analog signal is a copy of the output signal of the amplification module, and the analog signal is digitized to obtain detection data; the detection module performs time division on the acquired detection data; namely, generating a small segment of fragment audio data at fixed time intervals T; performing frequency domain conversion on the generated fragment audio data to obtain a frequency spectrum of the fragment audio data;

the detection module reserves data with the center frequency of F and the width of W in the fragment audio data, and deletes the rest of the data to obtain tracing fragment audio data; processing the audio data of the tracing fragments to obtain the central frequency F _n And half width W _n And central frequency intensity H _n (ii) a Where n is the number of the fragment audio data, i.e. the nth fragment audio data。

Centering frequency F along time _n And half width W _n And central frequency intensity H _n Three curves are generated, the abscissa is n, and the ordinate is the central frequency F _n And half width W _n And central frequency intensity H _n The value of (c).

Detection module for detecting center frequency F _n And half width W _n And central frequency intensity H _n Is not within a threshold range, the threshold including an upper threshold and a lower threshold;

the detection modules respectively calculate the center frequencies F exceeding the threshold values _n And half width W _n Or intensity of center frequency H _n The duration of (d);

displaying the central frequency F on the ordinate on the display module _n And half width W _n And central frequency intensity H _n Shows the center frequency F exceeding the threshold _n And half width W _n Or intensity of center frequency H _n And marks a curve that is not within the threshold range to indicate the operating state of the calibration module.

Example 2:

with reference to figures 2-3 of the drawings,

the circuit example specifically includes a mode controller 1, a count window generator 2, a counter 3, a synchronous frequency divider 4, a LUT5, a subtractor 6, an FIR filter 7, a sliding mode filter 8, a low noise DAC9, an analog loop filter 10, and a wideband VCO11; the method also comprises silence detection 13, FIFO control 14, large-capacity buffer FIFO15 and I2S timing generation 12.

The I2S time sequence and data are input and then divided into 3 paths, one path enters a mute detection 13 and then enters an FIFO control 14, the second path enters a large-capacity cache FIFO15, and the third path enters a counter 3; the input I2S _ MCLK enters the counter 3;

the 10MHz high-precision reference clock enters a counting window generator 2 and then enters a counter 3; after the sampling rate is input into the mode controller 1, the sampling rate enters a counting window generator 2, an LUT5 and a sliding mode filter 8 (FIR + IIR);

the mode controller connects the FIFO control 14, LUT5, and sliding mode filter 8 (FIR + IIR);

counter 3 outputs to LUT5 and subtractor 6, lut5 outputs to subtractor and sliding mode filter 8 (FIR + IIR), subtractor outputs to FIR filter 7;

the sliding mode filter 8 (FIR + IIR) outputs to a low-noise DAC9, then outputs to an analog loop filter 10 and then outputs to a wideband VCO11;

the wideband VCO outputs to the synchronous frequency divider 4, the I2S timing generation 12 and the MCLK outputs;

I2S timing generation 12 outputs to FIFO control 14 and I2S output; the FIFO control 14 is connected with a large-capacity cache FIFO15; the large-capacity buffer FIFO15 is connected to the I2S timing generation 12.

The foregoing description of the embodiments has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same elements or features may also vary in many respects. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.

Example embodiments are provided so that this disclosure will be thorough and will fully convey the scope to those skilled in the art. Numerous details are set forth, such as examples of specific parts, devices, and methods, in order to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In certain example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms "comprises" and "comprising" are intended to be inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed and illustrated, unless explicitly stated as an order of performance. It should also be understood that additional or alternative steps may be employed.

Claims (7)

1. An earphone amplifier for calibrating frequency deviation of a sound source comprises an input interface, an output interface, a calibration module and an amplification module; the method is characterized in that:

the device also comprises a sound source module, a superposition module, a detection module and a display module;

the sound source module sends digital audio data to the superposition module, high-frequency tracing audio is superposed in the superposition module, and the superposed audio data is sent to the input interface to enter the calibration module;

the calibration module is arranged between the input interface and the amplification module and is used for calibrating the frequency deviation of the sound source;

the amplifying module is connected with an output interface, and the output interface is connected with a sound playing device;

the amplifying module is further connected with a detection module, the detection module detects and extracts high-frequency tracing audio from the audio amplified by the amplifying module, the high-frequency tracing audio is analyzed, and an analysis result is displayed on the display module.

2. The headphone amplifier for calibrating frequency offset of an audio source of claim 1, wherein:

the superposition module is provided with a 20MHz high-precision clock, and after acquiring the audio data sent by the sound source module, the superposition module superposes the audio data of the fixed frequency F and the audio data sent by the sound source; the value range of F is 20kHz-24kHz.

3. The headphone amplifier for calibrating frequency offset of an audio source as claimed in claim 2, wherein:

the specific mode of audio superposition is one of the following two modes:

the first method is as follows: the superposition module acquires a clock path signal of the digital audio sent by the sound source module and generates digital audio data with fixed frequency F according to the clock path signal of the sound source;

directly adding the generated digital audio data with the fixed frequency F and the digital audio format data sent by the sound source module on a data track to obtain superposed mixed audio data, wherein the mixed audio data comprises the audio with the fixed frequency F;

the second method comprises the following steps: and an ADC (analog-to-digital converter) module and a DAC (digital-to-analog converter) module are arranged in the superposition module, digital audio sent by the sound source module is subjected to digital-to-analog conversion, then the audio with fixed frequency F pre-stored in the superposition module is directly superposed with the audio of the sound source module to obtain mixed audio of analog signals, and then the mixed audio is subjected to analog-to-digital conversion and output.

4. The headphone amplifier for calibrating frequency offset of an audio source of claim 1, wherein:

the calibration module comprises a reference clock, a sampling rate input, an I2S input, a cache module, a frequency synthesis module and an output module;

the reference module and the sampling rate input are both connected to the frequency synthesis module, and the frequency synthesis module performs local clock frequency locking on the sampling rate and performs local clock frequency detection; calculating the difference value between the sampling rate and the I2S input clock and the local clock, and further setting the direction and the depth of a cache sequence according to the difference value to realize the correction of clock deviation;

the frequency synthesis module comprises a mode controller (1), a counting window generator (2), a counter (3), a synchronous frequency divider (4), an LUT (5), a subtracter (6), an FIR filter (7), a sliding mode filter (8), a low-noise DAC (9), an analog loop filter (10) and a broadband VCO (11);

the reference module outputs a 10MHz high-precision reference clock to a counting window generator (2);

the sampling rate information is sent to a mode controller (1) so as to output frequency switching control parameters to an LUT (5), meanwhile, the mode of a sliding mode filter (8) is controlled to be fast frequency switching, and the filtered control data is sent to a low-noise DAC (9) and is output to a VCO (11) after passing through an analog loop filter (10);

the VCO output is sent to a synchronous frequency divider (4), and then sent to a frequency measurer consisting of a counting window generator (2) and a counter (3) to complete frequency measurement; the frequency measurement result is sent to the LUT (5) and the mode controller (1), and the mode controller (1) controls the loop;

input I2S data is sent into a large-capacity buffer (15), a mode controller (1) obtains the difference value of sampling rate information and an I2S input clock through an LUT (5) unit, and the buffer sequence direction and the buffer depth of the FIFO are set through the difference value.

5. The headphone amplifier for calibrating frequency offset of an audio source as recited in claim 4, wherein:

the maximum depth of the large-capacity cache (15) can ensure that the CD disk is played for 74 minutes and no leakage occurs; meanwhile, a silence detection module is arranged, wherein the silence detection is a protection mechanism, and a large-capacity cache (15) is reset in a silence segment; by resetting the mass buffer (15), a continuous and stable operation of the system can be ensured.

6. The headphone amplifier for calibrating frequency offset of an audio source of claim 1, wherein:

the detection module acquires an analog signal from the output of the amplification module, wherein the analog signal is a copy of the output signal of the amplification module, and the analog signal is digitized to obtain detection data; the detection module performs time division on the acquired detection data; namely, generating a small segment of fragment audio data at fixed time intervals T; performing frequency domain conversion on the generated fragment audio data to obtain a frequency spectrum of the fragment audio data;

the detection module reserves data with the center frequency of F and the width of W in the fragment audio data, and deletes the rest of the data to obtain tracing fragment audio data; processing the audio data of the tracing fragments to obtain the audio dataHeart frequency F _n And half width W _n And central frequency intensity H _n (ii) a Wherein n is the serial number of the fragment audio data, namely the nth fragment audio data tracing;

centering frequency F along time _n And half width W _n And central frequency intensity H _n Three curves are generated, the abscissa is n, and the ordinate is the central frequency F _n And half width W _n And central frequency intensity H _n The value of (c).

7. The headphone amplifier for calibrating frequency offset of an audio source of claim 6, wherein:

detection module for detecting center frequency F _n And half width W _n And central frequency intensity H _n Is not within a threshold range, the threshold including an upper threshold and a lower threshold;

the detection modules respectively calculate the center frequencies F exceeding the threshold values _n And half width W _n Or intensity of center frequency H _n The duration of (d);

displaying the central frequency F on the ordinate on the display module _n And half width W _n And central frequency intensity H _n Shows the center frequency F exceeding the threshold _n And half width W _n Or intensity of center frequency H _n And marks a curve that is not within the threshold range to indicate the operating state of the calibration module.

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