声波是实现井下信息快速准确传输的重要手段之一，钻杆等周期性管结构的声波频率响应表现出通带与阻带交替出现的梳状滤波特征。为分析实际工况中钻柱信道频谱质量，提出了基于改进雷达图法的声波频谱多级评价方法，利用该方法分析研究了轴向拉应力对管结构中声波频谱特性的影响，并建立了判别标准。实践表明：拉应力的存在对声波频谱及频谱中通带特性影响显著，随拉应力增加，频谱特性评价指标先增后减，存在频谱特性最优的峰值点。该方法能够较为全面地反映不同影响因素对钻柱信道中声波频谱特性的影响，从多角度对频谱特性的畸变程度进行了全面评价，对井下信息声传输技术现场应用过程中应对多因素干扰时的载波频率优选及中继器安装位置设计提供依据。

Acoustic wave is one of the important means to realize the fast and accurate transmission of downhole information. The drill string serving as information transmission channel has obvious periodic pipe structure characteristics. In order to study the frequency spectrum quality of drill string channel in actual working conditions, a multilevel evaluation method of acoustic frequency spectrum based on improved radar chart was provided. The influence of axial tension stress on the frequency spectrum characteristics of acoustic wave in pipe structure was studied and analyzed by the method, and the criteria for judging the frequency spectrum characteristics were established. Practice shows that, the existence of tensile stress has a significant impact on the acoustic frequency spectrum and passband characteristics. With the increase of tensile stress, the evaluation index of frequency spectrum characteristic increases first and then decreases, and there exists a peak point with the best frequency spectrum characteristic. This method can comprehensively reflect the influence of different factors on the frequency spectrum characteristics of acoustic wave in drill string channel, and comprehensively evaluate the distortion degree of frequency spectrum characteristics from the multiple perspectives. It provides a basis for optimizing carrier frequency and designing the installation position of repeater when dealing with multi-factors interference in the field application of downhole information acoustic transmission technology.