CN1953333A - Signal processing method and device - Google Patents

Signal processing method and device Download PDF

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CN1953333A
CN1953333A CN 200610114532 CN200610114532A CN1953333A CN 1953333 A CN1953333 A CN 1953333A CN 200610114532 CN200610114532 CN 200610114532 CN 200610114532 A CN200610114532 A CN 200610114532A CN 1953333 A CN1953333 A CN 1953333A
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CN100492912C (en )
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郦文其
冯宇红
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北京中星微电子有限公司
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Abstract

The invention relates to a signal processing method, which comprises that: A, amplifying analogue signal according present increment value, to be converted into digit signal; B, reducing said digit signal according to present increment value to be output, and outputting new increment value based on the digit signal, using said new increment value to refresh present increment value when the analogue signal is zero, feeding back to step A. The invention also provides a signal processor, which can dynamically adjust the reduce ratio of input signal according to the amplitude of input signal, to improve the signal/noise ratio.

Description

一种信号处理方法及装置 A signal processing method and apparatus

技术领域 FIELD

本发明涉及信号处理技术,特别是指一种提高模数转换(A/D)信噪比的信号处理方法及装置。 The present invention relates to signal processing technologies, and particularly to a signal processing method and apparatus for analog to digital converter (A / D) to improve the signal to noise ratio.

背景技术 Background technique

随着信号数字化的发展,由于数字信号如数字音频信号在传输时更方便、抗干扰性更强、更可靠,在处理时处理速度更快、精度更高,因此,经常需要将模拟信号转化为数字信号进行传输和处理。 With the development of digital signal, because the digital signal as a digital audio signal at the transmission easier, stronger anti-interference, more reliable, faster processing, greater accuracy in processing, therefore, often necessary to be converted to analog signals digital signal transmission and processing. 现有技术中,将模拟信号转化为数字信号的处理过程很简单,一般就是直接采用模数转换器(ADC),将输入的模拟信号进行模数转换,输出数字信号继续进行处理。 In the prior art, the analog signal into a digital signal processing procedure is simple, generally employed is a direct analog to digital converter (the ADC), an input analog signal is analog to digital conversion, a digital output signal processing continues. 但是,在将模拟信号通过ADC变成数字信号的过程中,通常会引入量化噪声,输入信号与量化噪声的信噪比(SNR,Signal Noise Ratio)可根据公式(1)得到:SNR=6.02B+1.76+10*log10(fm/2*fmax) (1)公式(1)中,B为量化位数,fm为采样频率,fmax为输入模拟信号的最高带宽。 However, during the analog signal into a digital signal by the ADC, the quantization noise is often introduced into the input signal and the quantization noise signal to noise ratio (SNR, Signal Noise Ratio) can be obtained according to the equation (1): SNR = 6.02B + 1.76 + 10 * log10 (fm / 2 * fmax) (1) equation (1), B is the number of quantization bits, fm is the sampling frequency, fmax is the maximum bandwidth of the input analog signal.

从公式(1)可以看出,信号量化后的位数每增加1位,SNR就会提高约6dB。 As can be seen from equation (1), the number of bits per quantized signal increases a, the SNR will increase approximately 6dB. 这样,对于幅值较大的输入信号,由于有效的量化位数较多,能获得较高的SNR;而对于幅值较小的输入信号,有效量化位数相对较少,所以信号量化后只能获得较低的SNR,甚至可能出现小信号在量化后完全被噪声污染的情况。 Thus, for large amplitude input signals, as more efficient quantization bits, the SNR can obtain higher; for smaller input signal amplitude, relatively less effective quantization bits, so only the quantized signal You can get lower SNR, even the case of small signal completely after quantization noise pollution may occur.

发明内容 SUMMARY

本发明的提供一种信号处理方法与装置,能根据输入信号幅值的大小进行自动增益控制,动态调整对输入信号的放大比率,有效提高模数转换中的量化信噪比。 Provide a signal processing method and apparatus according to the present invention, automatic gain control can be performed according to the magnitude of the amplitude of the input signal, dynamically adjust amplification ratio of the input signal, effectively improve the quantization noise ratio of analog to digital conversion.

本发明方法包括:A、将模拟信号根据当前给定增益值进行放大,再将放大后的模拟信号转换为数字信号;B、将所述数字信号按照所述当前给定增益值进行缩小后输出,并根据所述数字信号确定出新增益值,在模拟信号幅值为零时刻用所述新增益值更新所述当前给定增益值,返回步骤A。 The method of the present invention comprises: A, the analog signal is amplified in accordance with the current value of a given gain, the analog signal is converted into a digital signal and then amplified; outputs B, and the digital signal is reduced in accordance with the current value of a given gain and determining said digital signal in accordance with a new gain value, the analog signal amplitude at zero time with the new gain value is updated to the current gain value set, returns to the step A.

根据本发明的上述方法,步骤B中所述根据数字信号确定出新增益值,具体包括:B1、以样本块为单位对所述数字信号样本进行低通滤波,并计算各样本的包络信号,统计出各包络信号的最大值;B2、将所述包络信号的最大值与当前给定噪声阈值、增益上限值和增益下限值进行比较,确定出所述新增益值。 According to the method of the present invention, Step B, the digital signal in accordance with a new gain value is determined, comprises: B1, a sample block as a unit of the digital low-pass filtering of signal samples, and calculates the envelope of each sample signal, the maximum count in each envelope signal; B2, the maximum value of the envelope signal with a given noise threshold current, the lower and upper gain limit value comparison gain, the new gain value is determined .

步骤B1中所述计算各样本的包络信号,具体包括:当前样本的包络信号等于当前样本的绝对值与权重因子之积加上前一样本的包络信号与1减权重因子之积,其中,权重因子的值为0.2或为0.01。 Said calculating step B1 envelope signal of each sample, comprises: the current sample signal is equal to the absolute value of the envelope and the right of the current weight of the sample prior to adding the same volume factor of this envelope signal with a reduced weighting factor of the product, wherein the weighting factor is 0.2 or 0.01.

步骤B2中所述当前给定噪声阈值随所述当前给定增益值动态改变。 The current step B2 given noise threshold current with the predetermined gain value to be changed dynamically.

所述当前给定噪声阈值随所述当前给定增益值动态改变,具体包括:当所述当前给定增益值增加一个固定值时,将所述当前给定噪声阈值乘以一个大于1的第一因子,作为改变后的当前给定噪声阈值;当所述当前给定增益值减小一个固定值时,将所述当前给定噪声阈值乘以一个小于1的第二因子,作为改变后的当前给定噪声阈值;当所述当前给定增益值不变时,保持所述当前给定噪声阈值不变。 Said current value with a given noise threshold of the current value of the dynamic change given gain, specifically comprises: when the current increases to a fixed value when a given gain value, the current value is multiplied by the given noise threshold is greater than a first a factor, as the current changes after a given noise threshold; when the current value is decreased to a given gain to a fixed value, the noise current given threshold value multiplied by a second factor smaller than 1 as the changed current given noise threshold; when the current gain given constant value, maintaining the current constant for a given noise threshold.

所述当前给定噪声阈值随所述当前给定增益值动态改变,具体包括:预先存储增益索引值与放大因子的对应关系;根据所述包络信号的最大值确定出所述增益索引值,查找所述对应关系,得到所述放大因子; Said current value with a given noise threshold of the current value of the dynamic gain for a given change, comprises: index values ​​corresponding prestored gain relationship between amplification factor; determining an index value according to the gain maximum value of the envelope signal, Finding the correspondence relation, the amplification factor obtained;

用当前给定噪声阈值的初始值乘以所述放大因子,作为改变后的当前给定噪声阈值。 With the current value of a given noise threshold by multiplying the initial value of the amplification factor, a change in the current after a given noise threshold.

所述步骤B2包括:当所述包络信号的最大值小于所述当前给定噪声阈值、或者所述包络信号的最大值大于等于所述增益下限值小于所述增益上限值时,确定出所述新增益值等于所述当前给定增益值;当所述包络信号的最大值大于等于所述当前给定噪声阈值且小于所述增益下限值时,确定出所述新增益值等于所述当前给定增益值增加一个固定值;当所述包络信号的最大值大于等于所述增益上限值时,确定出所述新增益值等于所述当前给定增益值减小一个固定值。 B2 comprises the step of: when the maximum value of the envelope signal is smaller than the current reference noise threshold, or the maximum value of the envelope signal is greater than or equal to the gain of the gain is smaller than the lower limit value upper limit, the new gain value is determined equal to the current value to the given gain; when the maximum value of the envelope signal is greater than or equal to the noise current given threshold and smaller than the lower limit of the gain, it is determined that the new gain equal to the current value of a given gain value is increased to a fixed value; when the maximum value of the envelope signal is greater than the upper limit value is equal to the gain, the new gain value is determined equal to the current given gain value is decreased to a fixed value.

根据本发明的上述方法,在所述步骤A之前还包括:设置所述当前给定增益值的初始值为0dB。 According to the method of the present invention, before the step A further comprises: setting the current to a predetermined initial gain value is 0dB.

本发明另提供一种信号处理装置,包括:信号放大单元,用于对所接收的模拟信号根据当前给定增益值进行放大,并将放大后的模拟信号发送到模数转换单元;模数转换单元,用于将输入的模拟信号转化为数字信号,并将数字信号输出至数字信号控制单元和自动增益控制单元;数字信号控制单元,用于将输入的数字信号根据所述当前给定增益值缩小后输出;过零点检测单元,检测所述模拟信号的幅值,在模拟信号幅值为零时刻发送通知消息给所述自动增益控制单元;自动增益控制单元,用于根据输入的数字信号确定出新增益值,并在接收到所述过零点检测单元发送的通知消息后,用所述新增益值更新所述当前给定增益值输出给所述信号放大单元和数字信号控制单元。 The present invention further provides a signal processing apparatus, comprising: a signal amplifying unit for receiving a current analog signal amplified in accordance with a given gain value, and transmits the amplified analog signal to the analog-digital conversion means; analog to digital conversion analog conversion means for converting an input digital signal, and outputs the digital signal to the digital signal control unit and the automatic gain control unit; a digital signal control unit for the digital signal inputted to the current value according to a given gain after the reduced output; zero-crossing detection means, detecting the amplitude of the analog signal through, zero time to transmit a notification message to said analog signal amplitude automatic gain control unit; automatic gain control unit, for determining a digital signal input new gain value, and after receiving the zero-crossing detection unit through the notification message sent by the new gain value is updated to the current value of the output gain given to the signal amplification unit and a digital signal control unit.

所述信号放大单元为可编程增益放大器。 The signal amplifying unit is a programmable gain amplifier.

所述自动增益控制单元包括: The automatic gain control unit comprises:

第一功能模块,以样本块为单位对所述数字信号样本进行低通滤波,并计算各样本的包络信号,统计出各包络信号的最大值;第二功能模块,将所述包络信号的最大值与当前给定噪声阈值、增益上限值和增益下限值进行比较,确定出所述新增益值;第三功能模块,接收所述过零点检测单元发送的通知消息,用确定出的新增益值更新所述当前给定增益值输出给所述信号放大单元和数字信号控制单元。 A first functional module, a sample block of the digital low-pass filtering signal samples as a unit, and calculates the envelope signal of each sample, the maximum value of each statistical envelope signal; a second function module, the envelope the maximum value of the current signal and a given noise threshold, a gain lower limit value and upper limit value for the gain comparison, the new gain value is determined; a third function module receiving the notification message through the zero-crossing detection unit sent by determining a new gain value is updated to the current value of the output gain given to the signal amplification unit and a digital signal control unit.

所述自动增益控制单元还包括:噪声阈值改变模块,当所述当前给定增益值改变时,动态改变当前给定噪声阈值。 The automatic gain control unit further comprising: a noise threshold change module, when the current a given gain value changes dynamically changing the current a given noise threshold.

本发明有益效果如下:(1)在本发明中,先将模拟信号根据当前给定增益值进行放大(初始值可设为0dB),再将放大后的模拟信号转换为数字信号;将转换后的数字信号按照当前给定增益值进行等比缩小后输出,同时根据转换后的数字信号确定出新增益值,在确定新增益值时,通过计算转换后的数字信号样本的包络信号,采取对小信号多放大、大信号少放大或缩小的处理方式来确定新的增益值,从而整体上提高量化信噪比。 Advantageous effects of the present invention are as follows: (1) In the present invention, the first analog signal (the initial value can be 0dB) amplifies the current value according to a given gain, the analog signal is converted into a digital signal and then amplified; the converted in accordance with the current digital signal for a given gain-scaling the output value, while the new gain value is determined according to the converted digital signal, when the new gain value is determined by calculating the digital signal sample converted envelope signal taking multiple small signal amplification, large signal enlarged or reduced little treatment to determine a new gain value, thereby improving the overall quantization noise ratio. 另外,本发明采用在模拟信号幅值为零时刻用所述新增益值更新当前给定增益值,对后续输入的模拟信号进行放大控制,可以有效减小转换后信号的频率失真。 Further, the present invention employs an analog signal amplitude at zero time with the new gain value is updated to the current value given gain, the analog signal inputted subsequent amplification control, can effectively reduce the frequency of the converted signal distortion.

(2)本发明在根据转换后的数字信号确定出新增益值时,用转换后的数字信号样本的包络信号与当前给定噪声阈值、增益上限值和增益下限值进行比较来确定出新增益值,其中,还使当前给定噪声阈值随当前给定增益值进行动态改变,这样,可有效地区分出噪声信号和有用信号(当包络信号的最大值小于当前给定的噪声阈值时,认为是噪声信号),从而避免对噪声信号的放大,进一步提高信噪比。 (2) According to the present invention, when the digital signal after the conversion is determined that the new gain value, a digital signal sample envelope signal after conversion with a given noise threshold current limit value and the lower limit on the gain of the gain comparing the new gain value is determined, which also make the current dynamically changing a given noise threshold value with the current value of a given gain, so that noise can be effectively separated regions and useful signals (when the envelope signal is less than the maximum current given when the noise threshold is considered noise signals), so as to avoid amplification of the noise signal, and further improve the SNR.

(3)在本发明提供的当前给定噪声阈值随当前给定增益值进行动态改变的具体方法中,提供了一种根据固定增益值来改变当前给定噪声阈值的方式,即当前给定增益值增加一个固定值时,将当前给定噪声阈值乘以一个大于1的第一因子,作为改变后的当前给定噪声阈值;当前给定增益值减小一个固定值时,将当前给定噪声阈值乘以一个小于1的第二因子,作为改变后的当前给定噪声阈值;当前给定增益值不变时,保持当前给定噪声阈值不变。 (3) in the present invention provides a given noise threshold value with the particular method of this dynamically changing a given gain value, there is provided a method to change the current to the embodiment given noise threshold according to a fixed gain value, i.e., the current given gain value increases when a fixed value, the noise current given threshold value multiplied by a first factor greater than 1, a given threshold value as the current noise after the change; the current is reduced to a fixed value of a given gain value, given the current noise a threshold value multiplied by a second factor less than 1, as the current changes after a given noise threshold; given the current gain value unchanged, to keep the current constant for a given noise threshold. 这种实现方式简单有效,但由于后一个噪声阈值与前一个噪声阈值相关联,会存在累计误差的问题。 This implementation is simple and effective, but because of a previous noise threshold associated with a noise threshold, there will be the problem of cumulative error. 为此,本发明还提供了另一种改变当前给定噪声阈值的方式,即:预先存储增益索引值与放大因子的对应关系;根据包络信号的最大值确定出增益索引值,查找所述对应关系,得到放大因子;用当前给定噪声阈值的初始值乘以获得的放大因子,作为改变后的当前给定噪声阈值。 To this end, the present invention also provides another way to change the current reference noise threshold, namely: the index value is pre-stored corresponding relation between the gain amplification factor; gain index determined based on the maximum value of the envelope signal, said lookup correspondence, to obtain amplification factor; current with a given noise threshold obtained by multiplying the initial value of the amplification factor, a change in the current after a given noise threshold. 这种实现方式只需存储一个对应关系表,通过增益索引值查表得到放大因子,用当前给定噪声阈值的初始值(该初始值预先设定)和获得的放大因子的乘积来更新当前给定噪声阈值,从而避免了模拟信号转换为数字信号过程中因量化造成的累计误差问题。 This implementation needs to store a correspondence table lookup table index value obtained by the gain amplification factor, the noise threshold with the current set to an initial value (the initial value set in advance), and the product obtained by the amplification factor of the current update to predetermined noise threshold, thereby avoiding cumulative error problem converting an analog signal to a digital signal by the quantization process caused.

附图说明 BRIEF DESCRIPTION

图1为本发明提供的信号处理装置的组成结构示意图;图2为本发明信号处理方法的实现流程图;图3为本发明提供的信号处理装置中自动增益控制单元模块结构示意图;图4为本发明方法中自动增益控制单元动态调整增益值的处理流程图。 2 is a flowchart implement a signal processing method of the present invention;; structural diagram of a signal processing apparatus of the present invention is provided in FIG. 1 FIG. 3 a schematic view of an automatic gain control unit configuration of the signal processing module of the present invention to provide apparatus; FIG. 4 is a a flowchart of processing unit dynamically adjusts the gain value of the method of the present invention, an automatic gain control.

具体实施方式 detailed description

自动增益控制(AGC,Automatic Gain Control)是一种通过改变输入信号的增益(Gain)值来调整信号幅值,使信号幅值限制在一个固定范围内的算法。 Automatic gain control (AGC, Automatic Gain Control) by changing a gain (Gain) signal to adjust the value input signal amplitude, the amplitude of the signal limiting algorithm in a fixed range. 目前,AGC算法在音频领域的应用,大多是用于调整音频信号的响度,使信号的音量保持在一个稳定响度,而不是忽大忽小。 Currently, AGC algorithm applied in the audio field, mostly used to adjust the loudness of audio signals, the volume of the signal is maintained at a steady loudness, rather than suddenly large and small. 本发明利用AGC能够动态调整、保持信号状态稳定的特点,对模拟音频信号的幅值进行动态调整。 The present invention utilizes can dynamically adjust the AGC, the signal state remains stable, the amplitude of the analog audio signal to be dynamically adjusted.

本发明的核心思想是:对模拟音频信号在进行转换前先放大,再将放大的模拟音频信号转化为数字音频信号,将转换后的数字音频信号按照之前放大的比例进行缩小。 The core idea of ​​the invention is: the former converts the analog audio signal is performed before amplification, and then the amplified analog audio signal into a digital audio signal, the converted digital audio signal is reduced in accordance with prior enlarged scale. 这里,对模拟音频信号进行放大的比例和对数字音频信号进行缩小的比例,是根据所输入的模拟音频信号的大小通过AGC动态调整的。 Here, the ratio of the analog audio signal is amplified and the ratio of reduced digital audio signal, based on the size of the analog audio signal inputted through the AGC dynamically adjusted. 其中,所述放大是指增大或减小音频信号的幅值。 Wherein said amplifying means to increase or decrease the amplitude of the audio signal.

如图1所示,本发明所提供的信号处理装置包括:信号放大单元11、模数转换单元12、数字信号控制单元13、自动增益控制单元14以及过零点检测单元15。 1, the signal processing apparatus according to the present invention is provided comprising: a signal amplifying unit 11, conversion unit 12, a digital signal control unit 13, an automatic gain control unit 14 and the zero-crossing detection unit 15. 其中,信号放大单元11用于将输入的模拟音频信号x(t)根据当前给定的增益值进行放大,并将放大后的模拟音频信号送至模数转换单元12;模数转换单元12用于将模拟信号转化为数字信号,并将转化后的数字信号x(n)同时送入数字信号控制单元13和自动增益控制单元14中;数字信号控制单元13用于根据给定的增益值对所收到的数字音频信号进行缩小,并输出缩小后的数字音频信号y(n);自动增益控制单元14用于对模数转换单元12输出的信号样本x(n)进行低通滤波,计算出各样本的包络信号,并统计出各包络信号的最大值,将统计出的输出信号样本的包络信号的最大值与当前给定的噪声阈值、增益调整上限值和增益调整下限值进行比较,确定出新的增益值,并用确定出的新增益值更新当前给定增益值;当过零点检测单元15检测到模拟输入信号的幅值为零时,通知 Wherein the analog audio signal x (t) for the signal amplification unit 11 amplifies the input according to the current value of a given gain, and the amplified analog audio signal to the analog-digital converting unit 12; conversion unit 12 with in the analog signal into a digital signal and the converted digital signal x (n) into the digital signal while the control unit 13 and the automatic gain control unit 14; the control unit 13 the digital signal for a given gain value in accordance with the received digital audio signal reduction, and outputs a digital audio signal y (n) of the reduced; automatic gain control unit 14 for the signal samples x (n) analog to digital conversion unit 12 outputs the low pass filtering, calculation an envelope signal of each sample, and counts each of a maximum value of the envelope signal, the maximum value of the envelope signal of the output signal sample with the current statistics on a given noise threshold, a gain adjustment value and a lower gain adjustment value determined by comparing the new gain value, and updates the current to a predetermined gain value with the new gain value is determined; when the magnitude of zero-cross detection unit 15 detects the analog input signal is zero, notify 给自动增益控制单元14;自动增益控制单元14接收到通知消息后,将更新后的当前给定增益值同时送至信号放大单元11和数字信号控制单元13,使信号放大单元11和数字信号控制单元13能根据更新后的当前给定增益值调整音频信号的大小。 14 to the automatic gain control unit; the automatic gain control unit 14 receives the notification message, the updated current value while the gain given to the signal amplification unit 11 and the digital signal control unit 13, a signal amplifying unit 11 and the digital control signal unit 13 can adjust the size of a given gain value of the audio signal according to the current updated.

本发明提供的上述装置中,信号放大单元11可采用可编程增益放大器(PGA);模数转换单元12一般采用模数转换器;数字信号控制单元13可采用数字信号处理(DSP)芯片或专用芯片实现;自动增益控制单元14可采用专用芯片或DSP芯片实现;数字信号控制单元13和自动增益控制单元14可使用同一个DSP芯片或同一个专用芯片。 The present invention provides the above-described apparatus, the signal amplifying unit 11 may employ a programmable gain amplifier (the PGA); conversion unit 12 typically uses digital converter; digital signal control unit 13 may employ digital signal processing (DSP) chip or a dedicated chip; automatic gain control unit 14 may employ a dedicated DSP chip or chips; digital signal control unit 13 and the automatic gain control unit 14 may use the same DSP chip or a dedicated chip same. 信号放大单元11所采用的当前给定增益值与数字信号控制单元13所采用的当前给定增益值相等。 Gain equal to the current value given to the current value of a given digital signal gain control unit 13 employed in the signal amplifying unit 11 is employed.

基于图1所示的装置,本发明的信号处理方法步骤流程如图2所示,包括:步骤S21:将当前要进行模数转换的模拟音频信号x(t)按照当前给定增益值进行放大。 Based apparatus shown in Figure 1, the signal processing method steps in the process of the present invention shown in Figure 2, comprising: Step S21: the analog audio signal to the current analog to digital conversion of x (t) is amplified in accordance with the current value of a given gain . 对模拟音频信号的放大由图1中的信号放大单元11完成;其中,当前给定增益值由自动增益控制单元14给出,以dB为单位,当前给定增益值的初始值为0dB。 The amplified analog audio signal is performed by the signal amplifying unit 11 of FIG. 1; wherein, given the current gain value is given by an automatic gain control unit 14, in units of dB, the current gain value to a predetermined initial value is 0dB.

步骤S22:将放大后的模拟音频信号转换为数字音频信号x(n)并输出。 Step S22: the amplified analog audio signal into a digital audio signal x (n) and outputs. 图1中,信号放大单元11将放大后的模拟信号输出至模数转换单元12,由模数转换单元12将模拟音频信号转换为数据音频信号,并输出给数字信号控制单元13和自动增益控制单元14。 1, the analog signal output from the signal amplifying unit 11 amplifies to a conversion unit 12, the digital audio signal from the 12 analog audio signal analog-digital conversion unit, and outputs to the digital signal control unit 13 and an automatic gain control unit 14.

步骤S23:对x(n)信号的幅值按照当前给定增益值进行缩小后输出,以补偿信号放大单元11对输入信号的放大;自动增益控制单元14根据输入的数字音频信号x(n)动态调整给定增益值,即根据输出的数字音频信号确定出新增益值,并用确定出的新增益值更新当前给定增益值;在模拟音频信号过零点时刻将更新后的当前给定增益值同时送至信号放大单元11和数字信号控制单元13;然后返回步骤S21,用更新后的当前给定增益值对后续接收的模拟音频信号进行放大控制。 Step S23: the amplitude x (n) signal according to the current reduction for a given value of the output gain to compensate for signal amplification unit 11 amplifies an input signal; automatic gain control unit 14 the digital audio signal x (n) input dynamically adjusting the gain of a given value, i.e., a new gain value output from the digital audio signal is determined in accordance with, and updates the current to a predetermined gain value with the new gain value is determined; the updated time at zero current through the analog audio signal given while the gain value to the signal amplification unit 11 and the digital signal control unit 13; then returns to step S21, the current with the updated gain value for the given subsequently received analog audio signal is amplified controls.

过零点检测指的是当输入的模拟信号幅值为0时,过零点检测器通知自动增益控制单元14,自动增益控制单元14接收到通知消息后再指示信号放大单元11和数字信号控制单元13改变当前给定增益值。 Zero crossing detection means when the analog input signal amplitude is zero, zero crossing detector 14 notifies automatic gain control unit, the automatic gain control unit 14 then receives the notification message indicating the signal amplification unit 11 and the digital signal control unit 13 to change the current set gain value.

采用过零点处更新当前给定增益值能减小频率失真,原理如下:假设第i-1个样本块的最后一个样本Xi-1(N-1)和第i个样本块的第一个样本Xi(0)应用的增益值分别为G(i-1)和G(i),如果G(i-1)不等于G(i),则由于增益的改变引起这两个相邻样本值不连续,引起信号的失真。 Updating the current zero crossing using the given frequency distortion can be reduced gain value, works as follows: assume that the first i-1 Xi-1 last samples of the sample block (N-1) and the first sample of the i-th sample blocks Xi (0) gain value applied respectively G (i-1) and G (i), if G (i-1) is not equal to G (i), since the gain change causes the two adjacent sample values ​​are not continuous, causing signal distortion. 如果失真发生在能量大的样本值处(对应信号幅值较大),该失真有可能被人耳能感知到,通常称为zipper(拉练)噪声。 If the distortion occurs in a large energy value at a sample (corresponding to the signal amplitude is large), the distortion is likely to be perceived by the human ear, commonly referred Zipper (zipper) noise. 为了减少zipper噪声,可以让增益改变发生在能量小的样本处,例如,过零点处。 In order to reduce zipper noise, the gain can make change happen in a small sample of the energy, for example, at the zero crossing. 因此,本发明采取在过零点处改变当前给定增益值,以减小频率失真和噪声。 Accordingly, the present invention is adopted to change the current gain value set at zero crossing to reduce frequency distortion and noise.

下面对自动增益控制单元14如何根据输入的数字音频信号x(n)确定出新增益值进行详细说明。 Next, how an automatic gain control unit 14 determines that the new gain value based on the digital audio signal x (n) input will be described in detail.

参见图3,自动增益控制单元14包括:第一功能模块141,以样本块为单位对数字信号样本进行低通滤波,并计算各样本的包络信号,统计出各包络信号的最大值;第二功能模块142,将包络信号的最大值与当前给定噪声阈值、增益上限值和增益下限值进行比较,确定出所述新增益值;第三功能模块143,接收过零点检测单元15发送的通知消息,用确定出的新增益值更新当前给定增益值输出给信号放大单元11和数字信号控制单元13;噪声阈值改变模块144,用于当前给定增益值改变时,动态改变当前给定噪声阈值。 Referring to Figure 3, an automatic gain control unit 14 comprises: a first functional module 141, a sample block units digital low-pass filtering signal samples, and calculates the envelope signal of each sample, the maximum value of each count of the envelope signal; the second functional module 142, the maximum value of the envelope signal with a given noise threshold current, the lower and upper gain limit value comparison gain, the new gain value is determined; a third function module 143, receives the zero-crossing noise threshold change module 144, a gain value for a given current change; notification message sent from the detecting unit 15, the determined gain value with the new updated value of the output current gain given to the signal amplification unit 13 and the digital signal control unit 11 dynamically changing the predetermined current value to the noise threshold.

根据输入的数字音频信号x(n)确定出新增益值的具体步骤如图4所示,包括:步骤S41:第一功能模块141以样本块(sample block)为单位,对数字音频信号样本x(n)进行低通滤波,并根据下列公式(2)得到包络信号e(n):e(n)=α|x(n)|+(1-α)e(n-1) (2)其中,α为权重因子,在attack阶段|x(n)|>e(n-1),此时α=0.2;其他阶段α=0.01。 DETAILED new step of determining a gain value of the digital audio signal x (n) input shown in Figure 4, comprising: Step S41: a first functional block 141 to blocks of samples (sample block) as a unit, the digital audio signal samples x (n) low-pass filtering, and (2) to obtain the envelope signal e (n) according to the following equation: e (n) = α | x (n) | + (1-α) e (n-1) ( 2) wherein, [alpha] is a weighting factor, the attack phase | x (n) |> e (n-1), this case α = 0.2; other phases α = 0.01. 通常,音频信号的变化可分为上升、保持和降低几个阶段,这里所述的attack阶段就是指上升阶段,保持和降低属于其他阶段。 Typically, changes in the audio signal may be divided into rising, holding and lowering stages, herein refers rising phase attack phase, holding phase, and reducing the other belongs.

步骤S42:第一功能模块141统计所有包络信号的最大值Emax,并将统计结果输出给第二功能模块142。 Step S42: a first functional module 141 statistical maximum value Emax of all of the envelope signal, and outputs the count result to the second functional block 142.

Emax=Max(e(n)) (3)也就是说,第一功能模块141获取L个样本的包络信号的最大值。 Emax = Max (e (n)) (3) That is, the first functional module 141 acquires the maximum value of the envelope signal of L samples.

式(3)中,n为0,...,L-1,L表示sample block的长度,通常sample block的长度可设置在64至256之间。 Of formula (3), n is 0, ..., L-1, L represents the length of the sample block, the sample block may be disposed generally between 64-256.

步骤S43:第二功能模块142将包络信号的最大值与当前给定噪声阈值、增益上限值和增益下限值进行比较,确定出新增益值,并根据新增益值的变化动态改变当前给定噪声阈值。 Step S43: the second functional block 142 the maximum value of the envelope signal and the current reference noise threshold, a gain lower limit value and upper limit value of the gain determined by comparing the new gain value, and the new gain value according to a change in the dynamic changing the predetermined current value to the noise threshold. 具体方法包括:设置三个阈值,分别为:当前给定噪声(noise)阈值NL(假设NL初值为noise_th,NL随当前给定增益值动态改变),增益上限值UL和增益下限值LL,LL和UL用于定义一个控制的目标范围。 Specific method comprising: providing three threshold values, namely: for a given current noise (Noise) threshold value NL (NL is assumed that the initial value noise_th, NL dynamically changes with the current value of a given gain), gain limit UL and the lower limit value of gain LL, LL and UL define a range for the target of control.

如果包络信号的最大值Emax小于NL值,可以认为是noise信号,则保持当前给定增益值不变;如果包络信号的最大值Emax大于等于LL值并且小于UL值,则认为达到了控制目标,可以保持当前给定增益值不变;如果包络信号的最大值Emax大于等于NL值并且小于LL值,则认为当前输入的信号幅度不够大,让增益值增加一个固定值(例如增加1.5dB);即新增益值为原来的当前给定增益值加上1.5dB,并用新增益值更新当前给定增益值;如果包络信号的最大值Emax大于等于UL值,则认为当前输入信号的幅值较大,让增益值减小一个固定值(例如减小1.5dB);即新增益值为原来的当前给定增益值减去1.5dB,并用新增益值更新当前给定增益值。 If the maximum value Emax of the envelope signal is less than the value of NL can be considered noise signal, the current is maintained constant for a given gain value; if the packet envelope signal is greater than a maximum value Emax value equal to and less than LL UL value, the control is considered to be reached target, the current can be kept constant for a given gain value; if the envelope signal is greater than a maximum value Emax value and less than LL NL equal value, the amplitude of the current input signal is considered not large enough, so that the gain value is increased to a fixed value (e.g., increased 1.5 dB); i.e., the new gain value of the current original value plus the given 1.5dB gain, and updates the current to a predetermined gain value with the new gain value; if the envelope signal is greater than a maximum value Emax UL equal value, that the current input signal amplitude is large, the gain value is decreased so that a fixed value (e.g. reduced 1.5dB); i.e., the original value of the new gain current by subtracting a given value 1.5dB gain, and the gain value is updated with the new current given gain value.

当前给定增益值更新后,输入信号中的背景噪声部分的幅值也将会发生变化,为了更加准确检测当前输入信号是语音信号还是噪声信号,需要根据更新后的当前给定增益值动态改变NL值。 The current value is updated after a given gain, the amplitude of the background noise portion of the input signal will also change, in order to more accurately detect the current input signal is a speech signal or a noise signal, the updated according to the current need to dynamically change the value of a given gain NL value. 因此,当前给定增益值更新后,由噪声阈值改变模块144动态改变当前给定噪声阈值,具体改变方法例如可采用如下两种方法:方法一:设置两个改变因子来实现动态改变当前给定噪声阈值。 Therefore, the current value is updated after a given gain, the noise threshold dynamically changing module 144 changes the current value to a predetermined noise threshold, for example, the specific method of changing the following two methods may be employed: a method of: providing two dynamic change factor given current change noise threshold. 具体包括:当当前给定增益值增加一个固定值时,将当前给定噪声阈值乘以一个大于1的第一因子,作为改变后的当前给定噪声阈值;当当前给定增益值减小一个固定值时,将当前给定噪声阈值乘以一个小于1的第二因子,作为改变后的当前给定噪声阈值;当当前给定增益值不变时,保持当前给定噪声阈值不变。 Comprises: a fixed value when the current increases to a given gain value, given the current noise threshold multiplied by a first factor larger than 1, a given threshold value as the current noise after the change; if the current value is reduced a given gain when a fixed value, the noise current given by a second threshold value is less than a factor of 1, as the current is changed after a given noise threshold; when the current gain given constant value, maintaining the current constant for a given noise threshold.

例如,假设增益值改变步长为1.5dB,当前给定增益值增加1.5dB时,NL采用下式(4)进行动态改变:NL=NL*1.19 (4)式(4)中,1.19即为大于1的第一因子;当前给定增益值减小1.5dB时,NL采用下式(5)进行动态改变:NL=NL*0.84 (5)式(5)中,0.84即为小于1的第二因子。 For example, assume that the gain value is changed in steps of 1.5dB, given the current gain value is increased 1.5dB, NL using the following equation (4) for dynamic changes: in NL = NL * 1.19 (4) Formula (4), namely 1.19 the first factor is greater than 1; and given the current gain value is decreased 1.5dB, NL dynamically changed using the formula (5): NL = the NL * 0.84 (5) of formula (5), that is, less than 0.84 to 1 two-factor.

以上第一因子和第二因子的具体数据可以设置,本发明对此不作限定。 Above a first factor and a second factor specific data can be provided, the present invention is not limited to this.

方法一简单有效,但根据式(4)、(5)可知,由于后一个噪声阈值与前一个噪声阈值相关联,会存在累计误差的问题。 A simple and effective method, but according to the formula (4), (5) can be seen, since after a previous noise threshold associated with a noise threshold, there will be the problem of cumulative error.

方法二:设置一个增益表,存储增益索引值与放大因子的对应关系来实现动态改变当前给定噪声阈值。 Method two: a gain setting table storing correspondence relationship between gain index value of the amplification factor to change the current dynamic given noise threshold. 具体包括:预先存储增益索引值(index)与放大因子的对应关系;根据统计出的包络信号的最大值Emax确定出增益索引值index,根据增益索引值查找增益表,得到对应放大因子;用当前给定噪声阈值的初始值(noise_th)乘以得到的放大因子,作为改变后的当前给定噪声阈值。 It comprises: pre-stored gain index value (index) of the corresponding relationship between the amplification factor; maximum value Emax is determined according to the statistics of the envelope signal, the gain index an index value, a gain table lookup based on the gain index, obtain a corresponding amplification factor; with given the initial current value (noise_th) the noise threshold obtained by multiplying the amplification factor, a change in the current after a given noise threshold.

其中,根据统计出的包络信号的最大值确定出增益索引值的方法,例如:当根据包络信号的最大值Emax确定出需要增加增益值时,使index加“1”;当根据包络信号的最大值Emax确定出需要减小增益值时,使index减“1”当根据包络信号的最大值Emax确定出不需要改变增益值时,使index不变;与各增益索引值对应的放大因子,例如由下式(6)计算获得:Gain_Table[index]=10dB[index]/20(6)式(6)中,dB[index]=index*1.5; Wherein the maximum value is determined according to the statistics of the envelope signal, a method of gain index value, for example: when it is determined that the gain needs to be increased based on the maximum value Emax of the envelope signal so that the index "1"; and when the envelope maximum value Emax is determined that the signal gain needs to be reduced, so that index minus "1" when it is determined necessary to change the gain based on the maximum value Emax of the envelope signal, so that the same index; each gain index corresponding to the value amplification factor, for example, calculated by the following formula (6) is obtained from: the Gain_Table [index] = 10dB [index] / 20 (6) formula (6), dB [index] = index * 1.5;

Index为根据当前统计出的包络信号最大值确定出的增益索引值。 Index is the maximum current statistics envelope signal gain determined according to the index value.

当NL初值为noise_th,则NL动态改变通过下式(7)实现:NL=noise_th*Gain_Table[index] (7)方法二采用增益表存储增益索引值和放大因子的对应关系,通过增益索引值查表得到放大因子,用当前给定噪声阈值的初始值(该初始值预先设定)和查表获得的放大因子的乘积来更新当前给定噪声阈值,从而避免了模拟信号转换为数字信号过程中因量化造成的累计误差问题。 When the initial value of NL noise_th, NL dynamically change the realization of the formula (7): NL = noise_th * Gain_Table [index] (7) a method using two values ​​of the gain and the gain index table storing correspondence relationship between amplification factor, the gain index amplification factor look-up table, the initial value of the current with a given noise threshold value (the initial value set in advance) and the product of the amplification factor of the obtained look-up table to update the current reference noise threshold, thereby avoiding an analog signal into a digital signal process the cumulative error problem caused due to quantization.

显然,本领域的技术人员可以对本发明进行各种改动和变型而不脱离本发明的精神和范围。 Obviously, those skilled in the art can make various modifications and variations to the invention without departing from the spirit and scope of the invention. 这样,倘若本发明的这些修改和变型属于本发明权利要求及其等同技术的范围之内,则本发明也意图包含这些改动和变型在内。 Thus, if these modifications and variations of the present invention fall within the claims of the invention and the scope of equivalents thereof, the present invention intends to include these modifications and variations.

Claims (12)

  1. 1.一种信号处理方法,其特征在于,该方法包括以下步骤:A、将模拟信号根据当前给定增益值进行放大,再将放大后的模拟信号转换为数字信号;B、将所述数字信号按照所述当前给定增益值进行缩小后输出,并根据所述数字信号确定出新增益值,在模拟信号幅值为零时刻用所述新增益值更新所述当前给定增益值,返回步骤A。 1. A signal processing method, wherein the method comprises the steps of: A, the analog signal is amplified in accordance with the current value of a given gain, the analog signal is converted into a digital signal and then amplified; B, the digital after the signal according to the current reduction for a given value of the output gain, and the new gain value is determined according to the digital signal, the analog signal amplitude at zero time with the new gain value is updated to the current value given gain , return to step A.
  2. 2.根据权利要求1所述的方法,其特征在于,步骤B中所述根据数字信号确定出新增益值,具体包括:B1、以样本块为单位对所述数字信号样本进行低通滤波,并计算各样本的包络信号,统计出各包络信号的最大值;B2、将所述包络信号的最大值与当前给定噪声阈值、增益上限值和增益下限值进行比较,确定出所述新增益值。 2. The method according to claim 1, wherein step B determines said new digital signal gain, specifically comprises: B1, a sample block as a unit of the digital low-pass filtering of signal samples , and calculates the envelope signal of each sample, the maximum value of each count envelope signal; B2, the maximum value of the envelope signal with a given noise threshold current, comparing the gain and the gain upper limit value for the lower limit, the new gain value is determined.
  3. 3.根据权利要求2所述的方法,其特征在于,步骤B1中所述计算各样本的包络信号,具体包括:当前样本的包络信号等于当前样本的绝对值与权重因子之积加上前一样本的包络信号与1减权重因子之积,其中,权重因子的值为0.2或为0.01。 3. The method according to claim 2, wherein said calculating step B1 envelope signal of each sample, comprises: the current sample signal is equal to the absolute value of the envelope and the right of the current weight of the sample plus the product of the factor as before this envelope signal with a reduced weighting factor of the product, wherein the weighting factor is 0.2 or 0.01.
  4. 4.根据权利要求2所述的方法,其特征在于,步骤B2中所述当前给定噪声阈值随所述当前给定增益值动态改变。 4. The method according to claim 2, wherein the step B2 given noise threshold current with the constant current value to dynamically change the gain.
  5. 5.根据权利要求4所述的方法,其特征在于,所述当前给定噪声阈值随所述当前给定增益值动态改变,具体包括:当所述当前给定增益值增加一个固定值时,将所述当前给定噪声阈值乘以一个大于1的第一因子,作为改变后的当前给定噪声阈值;当所述当前给定增益值减小一个固定值时,将所述当前给定噪声阈值乘以一个小于1的第二因子,作为改变后的当前给定噪声阈值;当所述当前给定增益值不变时,保持所述当前给定噪声阈值不变。 The method as claimed in claim 4, wherein said given noise threshold current with the current value of the dynamic change given gain, specifically comprises: when the current increases to a fixed value given gain value, given the current noise threshold multiplied by a first factor greater than 1, a given threshold value as the current noise after the change; when the current is reduced to a fixed value given gain value, given the current noise a threshold value multiplied by a second factor less than 1, as the current changes after a given noise threshold; when the current gain given constant value, maintaining the current constant for a given noise threshold.
  6. 6.根据权利要求4所述的方法,其特征在于,所述当前给定噪声阈值随所述当前给定增益值动态改变,具体包括:预先存储增益索引值与放大因子的对应关系;根据所述包络信号的最大值确定出所述增益索引值,查找所述对应关系,得到所述放大因子;用当前给定噪声阈值的初始值乘以所述放大因子,作为改变后的当前给定噪声阈值。 6. The method according to claim 4, characterized in that, with the current value of the current gain given to dynamically change a given noise threshold value comprises: pre-stored corresponding relation between gain index value of the amplification factor; in accordance with the the maximum value of the envelope signal, the gain of said index value is determined by searching the corresponding relationship, the amplification factor obtained; multiplied with the current amplification factor of the initial value for a given noise threshold, a change in the current after a given noise threshold.
  7. 7.根据权利要求4所述的方法,其特征在于,所述步骤B2包括:当所述包络信号的最大值小于所述当前给定噪声阈值、或者所述包络信号的最大值大于等于所述增益下限值小于所述增益上限值时,确定出所述新增益值等于所述当前给定增益值;当所述包络信号的最大值大于等于所述当前给定噪声阈值且小于所述增益下限值时,确定出所述新增益值等于所述当前给定增益值增加一个固定值;当所述包络信号的最大值大于等于所述增益上限值时,确定出所述新增益值等于所述当前给定增益值减小一个固定值。 7. The method as claimed in claim 4, wherein the step B2 comprises: when the maximum value of the envelope signal is less than said given noise threshold current, the maximum value of the packet or envelope signal is greater than or equal when the lower limit is less than the upper limit value of the gain of the gain, the new gain value is determined equal to the current value of a given gain; when the maximum value of the envelope signal is greater than or equal to the current reference noise threshold when the lower limit value and less than the gain, the new gain value is determined equal to the current gain value is increased a given fixed value; when the maximum value of the envelope signal is greater than or equal to the upper limit of the gain, the new gain value is determined equal to the current value is reduced by a fixed value given gain.
  8. 8.根据权利要求1至7任意权项所述的方法,其特征在于,在所述步骤A之前还包括:设置所述当前给定增益值的初始值为0dB。 Item 8. The method according to any of weights according to claim 1 to 7, wherein, prior to said step A further comprises: setting the current to a predetermined initial gain value is 0dB.
  9. 9.一种信号处理装置,其特征在于,包括:信号放大单元,用于对所接收的模拟信号根据当前给定增益值进行放大,并将放大后的模拟信号发送到模数转换单元;模数转换单元,用于将输入的模拟信号转化为数字信号,并将数字信号输出至数字信号控制单元和自动增益控制单元;数字信号控制单元,用于将输入的数字信号根据所述当前给定增益值缩小后输出;过零点检测单元,检测所述模拟信号的幅值,在模拟信号幅值为零时刻发送通知消息给所述自动增益控制单元;自动增益控制单元,用于根据输入的数字信号确定出新增益值,并在接收到所述过零点检测单元发送的通知消息后,用所述新增益值更新所述当前给定增益值输出给所述信号放大单元和数字信号控制单元。 A signal processing apparatus comprising: signal amplifying means for receiving an analog signal amplified in accordance with the current value of a given gain, and sends the amplified analog signal to the analog-digital conversion means; mold converts an analog signal to digital conversion means for converting an input digital signal, and outputs the digital signal to the digital signal control unit and the automatic gain control unit; a digital signal control unit for the input digital signal in accordance with said given current after the gain value output reduced; zero-crossing detector means detects the amplitude of the analog signal, the analog transmit a notification message to said timing signal amplitude is zero automatic gain control unit; automatic gain control unit for digital input after determining a new signal gain value, and receiving a notification message transmitting said zero-crossing detecting means, said new gain value is updated to the current gain value given to the signal amplification unit and the digital signal output control unit.
  10. 10.根据权利要求9所述的装置,其特征在于,所述信号放大单元为可编程增益放大器。 10. The apparatus according to claim 9, wherein said signal amplifying means is a programmable gain amplifier.
  11. 11.根据权利要求9所述的装置,其特征在于,所述自动增益控制单元包括:第一功能模块,以样本块为单位对所述数字信号样本进行低通滤波,并计算各样本的包络信号,统计出各包络信号的最大值;第二功能模块,将所述包络信号的最大值与当前给定噪声阈值、增益上限值和增益下限值进行比较,确定出所述新增益值;第三功能模块,接收所述过零点检测单元发送的通知消息,用确定出的新增益值更新所述当前给定增益值输出给所述信号放大单元和数字信号控制单元。 11. The apparatus according to claim 9, wherein said automatic gain control unit comprises: a first function module in units of a block of samples of said digital low-pass filtered signal samples, and each sample computing suite envelope signal, the maximum count in each envelope signal; a second function module, the packet with the maximum value of the envelope signal the current reference noise threshold, a gain lower limit value and upper limit value of the gain determined by comparing the said the new gain value; a third function module receiving the notification message through the zero-crossing detection unit transmitted by the determined new gain value is updated to the current value of the output gain given to the signal amplification unit and a digital signal control unit .
  12. 12.根据权利要求11所述的装置,其特征在于,所述自动增益控制单元还包括:噪声阈值改变模块,当所述当前给定增益值改变时,动态改变当前给定噪声阈值。 12. The apparatus as claimed in claim 11, wherein said automatic gain control unit further comprising: a noise threshold change module, when the current a given gain value changes dynamically changing the current a given noise threshold.
CN 200610114532 2006-11-14 2006-11-14 Signal processing method and device CN100492912C (en)

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CN103916769A (en) * 2012-12-31 2014-07-09 广州励丰文化科技股份有限公司 High-quality active integrated loudspeaker
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