差别

这里会显示出您选择的修订版和当前版本之间的差别。

--- sigma_delta_modulator [2022/02/23 13:59]
gongyusu [Delta Modulation (DM)]
+++ sigma_delta_modulator [2022/02/23 14:06] (当前版本)
gongyusu
@@ 行 1: / 行 1: @@
-### Delta调制（DM）
+## 增量调制（DM）
-Delta调试是一种将编码信息信号转换成1个二进制位流的调制方法，在这里只需要1位将1个电平进行编码，这种方式可以每一个取样点传输1位。
+增量调制（Delta调制）是一种将编码信息信号转换成1个二进制位流的调制方法，在这里只需要1位将1个电平进行编码，这种方式可以每一个取样点传输1位。
 由于PCM具有将消息信号直接转换成二进制编码脉冲序列的特性，因此增加了系统的带宽要求。因此，为了消除PCM的缺点，采用了增量调制。
+### Delta调制的工作原理
+DM的工作原理是将当前采样值与之前采样值进行比较，两者的差值决定传输值的增量或减量。简单地说，当两个样本值比较时，我们得到的差异要么具有正极性，要么具有负极性。
+如果极性差为正，则Δ表示的信号步长增加1。而当极性差为负时，则信号的阶跃减小，即Δ的减小。当+Δ被注意到，即步长增加时，则传输1。而对于-Δ，即步长减小，则传递0。因此，每个样本只允许传输一个二进制位。
+### 增量调制的框图
-### Operating principle of Delta Modulation
+首先让我们了解增量调制信号的产生。
-The operating principle of DM is such that, a comparison between present and previously sampled value is performed, the difference of which decides the increment or decrement in the transmitted values.
+增量调制信号的产生
+产生增量调制信号的框图如下:
-Simply put, when the two sample values are compared, either we get difference having a positive polarity or negative polarity.
-If the difference polarity is positive, then the step of the signal denoted by Δ is increased by 1. As against in case when difference polarity is negative then step of the signal is decreased i.e., reduction in Δ.
-When +Δ is noticed i.e., increase in step size, then 1 is transmitted. However, in the case of –Δ i.e., decrease in step size, 0 is transmitted.
-Hence, allowing only a single binary bit to get transmitted for each sample.
-### Block diagram for Delta Modulation
-Let us first understand the generation of delta modulated signal.
-Generation of delta modulated signal
-The block diagram for the generation delta modulated signal is shown below:
 {{ ::block-diagram-for-delta-modulation-transmitter-1.jpg |}}
-As we can see the above figure consists of an LPF, a comparator, a product modulator along with pulse generator and quantizer. Here, a feedback path is also provided to the circuit, where the output of modulator acts as input to the comparator.
+正如我们可以看到上图由LPF，比较器，积调制器以及脉冲发生器和量化器组成。在这里，一个反馈路径也提供给电路，其中调制器的输出作为输入比较器。
+将要传输的消息信号馈送给低通滤波器，该滤波器通过低频分量并消除高频分量。它也被称为混叠滤波器。
-The message signal that is to be transmitted is fed to a low pass filter that passes the low-frequency component and eliminates the high-frequency component. It is also referred to as aliasing filter.
+然后将LPF的输出给比较器，比较器将消息信号m(t)与任意信号m'(t)进行第一次比较。比较器比较两个信号后产生两者的差值。
+这种差异可以是正极性，也可以是负极性。这取决于被减去的消息和任意信号。
-The output of LPF is then given to a comparator unit, which compares the message signal m(t) with an arbitrary signal m'(t) for the first time. The comparator after comparing 2 signals generates the difference between the two.
+这个差值信号现在作为乘积调制器的输入。调制器的另一个输入是由脉冲发生器产生的脉冲信号。这两个信号在调制器中相乘。
+调制器的输出是一个脉冲信号，其脉冲大小相等，具有正极性和负极性。
-The difference can be of either positive polarity or negative polarity. This depends on message and arbitrary signals that are getting subtracted.
+极性完全取决于比较器的输出。调制器的输出给量化器。量化器以步骤的形式生成输出。
+如果正向幅度脉冲提供给量化器作为其输入，那么量化器执行1步长的增量，Δ。这是很容易理解的，在调制器的输出正脉冲表明消息信号大于任意信号。因此量化器将Δ增加1。
-This difference signal now acts as input to the product modulator. Another input to the modulator is a pulse signal generated by the pulse generator. These two signals are multiplied in the modulator.
+类似地，当脉冲为负幅值时，步长减小1。这是因为m'(t)大于m(t)，因此产生了一个负极性的脉冲。
+因此，量化器将Δ减少1。
-The output of the modulator is a pulsed signal whose pulses will be of equal magnitude having polarity either positive and negative.
+与此同时，调制器的输出通过反馈路径提供给蓄能器。
+累加器只不过是一种存储信号以供进一步操作的装置。累加器的输出现在的行为类似于比较器的第二个输入。因此，我们说当前的采样值与前一个采样值进行比较，以便进行进一步的操作。
-The polarity totally depends on the output of the comparator. The output of the modulator is given to quantizer. The quantizer generates the output in the form of steps.
+因此，这个过程以这种方式重复。
+最后，根据阶梯信号，如果步长为+Δ，则发送二进制1，如果步长为-Δ，则发送二进制0。
-If positive magnitude pulse is provided to the quantizer as its input then quantizer performs increment by 1 step size, Δ. It is very easy to understand that positive pulse at the output of the modulator shows that message signal is greater than the arbitrary signal. Thus quantizer increases Δ by 1.
-Similarly, in the case of negative magnitude pulse, the step size gets decreased by 1. This is so because m'(t) exceeds m(t), thereby generating a pulse of negative polarity.
-Thus, quantizer decreases Δ by 1.
-The output of the modulator at the same time, through a feedback path, is provided to the accumulator.
-An accumulator is nothing but a device that stores the signal for further operation. The output of the accumulator now behaves like the second input of the comparator. Thus, we say that the present sample value is compared with the previous one for further operation.
-Hence the process repeats in such a manner.
-In the end, depending on the staircase signal if the step size is +Δ then binary 1 is transmitted and if it is –Δ then binary 0 is transmitted.
 Waveform Representation of Delta Modulation
 The figure below shows the delta modulation waveform:
 {{ ::waveform-representation-of-delta-modulation.jpg |}}
-Here, the analog input signal is m(t) and the quantized signal is denoted by u(t). The binary sequence according to the step size that is actually transmitted is shown at the bottom of the figure shown above.
+这里，模拟输入信号为m(t)，量化后的信号表示为u(t)。根据实际传输的步长，二进制序列显示在上图的底部。
+增量调制信号的检测
-Detection of delta modulated signal
+增量调制信号的检测不是一个复杂的过程，在某种程度上与增量调制信号的产生相反。
+下图是增量调制信号检测表示的框图。
-The detection of a delta modulated signal is not a complex process and is somewhat reverse of generation of a delta modulated signal.
-The figure below shows the block diagram for the representation of detection of delta modulated signal.
 {{ ::block-diagram-for-delta-modulation-receiver-1.jpg |}}
-The detection circuitry basically consists of an accumulator and an LPF. The binary signal transmitted is provided to the accumulator section.
+检测电路主要由蓄电池和LPF组成。传输的二进制信号被提供给累加器部分。
+累加器由累加单元和延迟单元组成。传输信号和延迟信号一起加到求和单元。
-The accumulator consists of a summation unit and a delay unit. The transmitted signal along with the delayed signal is added at the summation unit.
+如果这里的输入是二进制1，那么经过一段延迟后，累加器的输出显示步长增加+Δ。然而，在二进制0作为输入的情况下，步长会减少。这将生成与消息信号等价的楼梯信号。
+蓄电池的输出提供给LPF, LPF平滑阶梯信号，以恢复原始的信息信号。
-If here the input is binary 1 then after a delay the output of the accumulator shown increased step size +Δ. However, in the case of binary 0 as input, a decrease in step size is noticed. This generates the staircase signal equivalent to the message signal.
+增量调制的优点
-The output of the accumulator is provided to the LPF that smoothens the staircase signal in order to regenerate the original message signal.
+  * 由于每个样本传输1比特，它允许低通道带宽以及信令速率。
+  * 不需要ADC。这样便于生成和检测。
-Advantages of delta modulation
+增量调制的缺点
-  * Due to transmission of 1 bit per sample, it permits low channel bandwidth as well as signaling rate.
+  * 普通列表项目增量调制导致的缺点，如斜率超载失真和颗粒噪声。
-  * ADC is not required. Thus permits easy generation and detection.
-Disadvantages of delta modulation
-  * Delta modulation leads to drawbacks such as slope overload distortion and granular noise.
-Applications of delta modulation
+增量调制的应用
-It is widely used in radio communication devices and digital voice storage and voice information transmission where signal quality is less important.
+它广泛应用于无线电通信设备、数字语音存储和语音信息传输等信号质量不太重要的领域。