A training mode adaptive quantizer
A training mode adaptive quantizer
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训练模式自适应量化器
DOI：
10.1109/tit.1974.1055297
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发表时间：
1974
期刊：
影响因子：
--
通讯作者：
D. Goodman
中科院分区：
文献类型：
--
作者：
A. Gersho;D. Goodman
与已知功率信号的量化器相比，必须适应大范围信号功率的量化器通常需要大量的输出电平。本文描述了一种信号功率先验未知但在通信过程中保持恒定的情况下的量化方案。由于在初始训练期间将量化器幅度范围调整为适合于当前信号功率的值，因此减少了所需的电平数。在训练期间的每个采样时间，振幅范围通过乘法量进行调整，该乘法量取决于最近的量化输出和自训练开始以来经过的时间。假设输入独立同分布，量化器范围收敛于输入均方根值的固定倍数。最终范围与有效值输入的比值是乘法器的一个独特函数，并且给出了一个公式，允许设计者选择乘法器，从而产生任何期望的距离与信号比。对于每个最终比率，都有许多乘数集，并且推导出公式，表明在有限的训练周期内，量化器范围的精度与量化器可以适应的信号功率集的大小之间的权衡。计算机模拟演示了特定乘数序列的效果。
A quantizer that must accommodate a wide range of signal powers would ordinarily require a large number of output levels compared to a quantizer of signals with known power. In this paper a quantizlng scheme is described for situations in which the signal power is unknown a priori but remains constant for the duration of a communication. The required number of levels is reduced because the quantizer amplitude range is adjusted during an initial training period to the value appropriate to the current signal power. At each sample time during the training period, the amplitude range is adjusted by a multiplicative quantity that depends on the most recent quantized output and upon the time elapsed since the onset of training. Assuming independent identically distributed inputs, it is shown that the quantizer range converges to a fixed multiple of the rms value of the input. The ratio of final range to rms input is a unique function of the multipliers, and a formula is presented that allows a designer to choose multipliers that result in any desired range-to-signal ratio. For each final ratio, there are many sets of multipliers, and formulas are derived that indicate, for a limited training period, the tradeoff between the accuracy of the quantizer range and the size of the set of signal powers to which the quantizer can adapt. Computer simulations illustrate the effects of particular multiplier sequences.