Nonlinear modulation is a promising technique for ultrasonic non-destructive damage identification. A wireless sensor network is ideally suited to monitor large structures using nonlinear modulation in a cost-efficient manner. However, existing approaches rely on high sampling rates and resource-demanding computations that are not feasible on low-cost and low-power sensor network devices. We present a new damage indicator that uses the short-time Fourier transform to derive amplitude and phase modulation with less computational effort and memory usage. Evaluation of the proposed method using real experiment data exhibits performance and reliability similar to the conventionally used modulation index. Undersampling is demonstrated, which reduces the memory demand in a test scenario by more than 100 times, and the required energy for sampling and processing more than four times. The loss of accuracy introduced by undersampling is shown to be negligible.

非线性调制是用于超声非破坏性损伤识别的有前途的技术。无线传感器网络非常适合以低成本方式使用非线性调制来监视大型结构。但是，现有方法依赖于高采样率和资源需求计算，而这在低成本和低功耗的传感器网络设备上是不可行的。我们提出了一种新的损伤指标，该指标使用短时傅立叶变换以较少的计算工作量和内存使用量来得出幅度和相位调制。使用实际实验数据对提出的方法进行评估，其性能和可靠性与常规使用的调制指数相似。演示了欠采样，可以将测试方案中的内存需求减少100倍以上，采样和处理所需的能量超过四倍。由欠采样引起的精度损失可忽略不计。