m伪随机序列中码元宽度选择及影响因素分析

Selection and Factors Analysis of the Code Width for m Pseudo-random Binary Sequence

码元宽度是m伪随机编码的重要参数之一,过宽无法保证高频部分信噪比,过窄则造成发射时间和能量的浪费。为此,本文首先研究了选择合适码元宽度的方法,并在总结相关数值模拟结果的基础上,给出了计算合适码元宽度的经验公式。随后,研究了影响合适码元宽度的因素,通过公式推导及数值模拟,表明均匀半空间下码元宽度应与电阻率成反比,与收发距平方成正比;一维模型中,合适码元宽度仍与电阻率成反比,但不再与收发距平方成正比。

In recent years,it is more popular using the pseudo-random binary sequence as the source current in electromagnetic method,because of its anti-noise performance.Code width is an important parameter of m pseudo-random binary sequence,determining the highest frequency of m pseudo-random binary sequence.Research show that code width should be selected appropriate,signal-to-noise of high frequency date is lower if the code width is too wide and it will waste of time and energy if the code wide is too narrow.It is studied for the selection method of the suitable code width by analyzing the frequency or time domain electromagnetic date.It summarize the results of numerical simulation models,and give the relevant empirical formula.Then,the factors are studied that affect the code width selection,and it shows that the code width,in uniform half-space model,should be proportional to the square of the offset and the conductivity.In the 1D model,it is still proportional to conductivity,but is no longer proportional to the square of the offset.