戈尔德(gold)序列在声学多输入多输出系统测量中的应用

Using gold sequences in multiple acoustic channel measurement

在多输入输出声学系统中,任意一对输入输出之间的脉冲响应在很多情况下需要同步测量。伪随机序列由于具有优良的相关特性从而在多输入、输出系统测量中得到了应用。运用具有优良相关特性的互逆最大长度线性移位寄存器序列对(m序列对)分别作为输入激励,然后计算两输出和输入m序列的相关,可以同步获得双输入输出系统的四个脉冲响应。当被测系统的输入多于两个时,互为优选的m序列对数目限制了它的应用。由互逆特征m序列对逐次经过τ倍间隔移位、模二加可以生成一个大的戈尔德(gold)序列集。该gold序列集中的序列除了具有和m序列相似的相关特性,即每一序列具有近似尖脉冲的自相关和两两序列间较小的互相关值外,还具有比m序列集多得多的独立优选对数。这些特性使gold序列成为同步多输入输出系统测量的首选激励信号。大量的仿真实验验证了gold序列用于声学多通道测量的可行性和有效性。

A wide variety of acoustic systems have multiple sources and receivers. Impulse responses between two separate sources and one or several receivers of acoustic systems need to be measured simultaneously. With its favorable correlation properties, a pseudorandom sequence is exploited in impulse response measurement simultaneously for multiple sources. The simultaneous dual-source measurements exploit excellent cross-correlation properties of reciprocal pairs of msequences. In the measurement of a dual source system, each of the reciprocal m-sequence pairs simultaneously excite one of two separate sources, two receiver signals cross-correlate in turn with each of the m-sequence pairs, resulting in impulse responses associated with two separate sources. Once the number of simultaneous sources is higher than 2, straightforward use of reciprocal m-sequence pairs cannot meet the need. A binary gold sequence can be generated by modulo-2 addition between a reciprocal binary m-sequence pair. In stepping t point-by-point, a large number of gold sequences result in a finite set. These gold sequences in the collection have pulse-like autocorrelation functions, and the cross-correlation functions between any pairs of signal drawn from the set have peak values that are significantly lower than the peak magnitude of autocorrelation function. This unique property, along with a sufficient number of single gold sequences in a collection satisfies the need of excitation signal for simultaneous acoustic multiple channel measurement. Computer simulation results demonstrate validity and feasibility of the proposed method.