Nilsen Carl-Inge Colombo, Holm Sverre
Dept. of Inf., Univ. of Oslo, Oslo, Norway.
IEEE Trans Ultrason Ferroelectr Freq Control. 2008 Aug;55(8):1719-28. doi: 10.1109/TUFFC.2008.857.
We have analyzed a compact, digital delay- and-sum beamformer using 1-bit delta-sigma A/D converters, where dynamic delays are applied directly to the delta-sigma modulated bitstream. It has previously been shown that the introduction of this time-variant operation into the time-invariant delta-sigma demodulator distorts the output signal, and several methods for minimizing this effect have been suggested. We have described the effect using standard system terminology. Based on this description, a new method for removing the distortion without any significant increase in system complexity is introduced. Its advantages, performance-wise, are supported by theoretical assessments and simulations.
我们分析了一种使用1位Δ-Σ模数转换器的紧凑型数字延迟求和波束形成器，其中动态延迟直接应用于Δ-Σ调制比特流。此前已经表明，将这种时变操作引入到时不变的Δ-Σ解调器中会使输出信号失真，并且已经提出了几种将这种影响降至最低的方法。我们使用标准系统术语描述了这种影响。基于此描述，引入了一种在不显著增加系统复杂度的情况下消除失真的新方法。从性能方面来看，其优势得到了理论评估和仿真的支持。
