idle tone和spurious tone的区别？

艾克0928

论坛里的大神，有木有人知道idle tone和spurious的区别啊？小弟在这两者之间有点懵……     我只知道idle tone就是空闲音，它是在sigma-delta ADC/DAC中很容易出现的一个问题，当输入信号接近直流或者是一个幅值为很小的正弦波时，在输出端就会产生一个很明显的tone，在听觉上而言就是“嘘嘘嘘~~~”的声音。      而根据百度搜索，人家解释spurious tone就是寄生波或杂波，或称为假音，英文解释是"Any tone that is other than a fundamental tone or its harmonics, and is generated within the back-to-back connected transmit and receive terminal or channel units, when the fundamental, i.e., a test sine wave, is applied to the transmit terminal or channel unit input."简单来说就是除去基波和谐波之外的其他音波成分都属于spurious的范畴。
       我的疑惑是有以下几点：
1. idle tones在频谱中是一种什么表现形式？
2. spurious tones在频谱中是周期性出现的吧？
3. idle tones和spurious tones本质上是不是同一个概念啊？
4. idle tones和spurious tones的消除方法有哪些？(注：我知道spurious tones的消除方法之一是可以添加dither)
     望大神们能给小弟解释解释，感激不尽！
      

艾克0928

别沉了啊，顶一下，求大神解惑！

艾克0928

再顶一下，大佬们，求解惑！

Wanye_guo

Sigma delta converters employ feedback and compare present input against output to change the output and they have long memory. If the input is constant, the error keeps growing slowly and after a overflow the same scenario repeats. This causes same bit pattern to occur periodically, which means that the quantization noise would not be uniform and will favor a definite frequency (heavily colored) which is the inverse of pattern repetition rate. When the pattern becomes long (inputs close to quantization level) the tone falls at very low frequency where noise shaping fails to push it out of the band. If the input changes slightly rather than being constant, the pattern is destroyed and it helps to spread the quantization noise more evenly across the spectrum resulting in better SNR and therefore more bits out of the converter

TeNs0r

Wanye_guo 发表于 2019-8-15 12:40
Sigma delta converters employ feedback and compare present input against output to change the output ...

thanks a lot ：）