结合信号重心与ASDF估计超声窄带信号时延

Time Delay Estimation Using ASDF and Center of Gravity for Narrowband Ultrasonic Signals

以ASDF(Average square difference function)作为超声窄带信号时延估计统计量,对其估计性能进行详尽的分析。并针对噪声对ASDF统计量极值的影响,提出结合信号重心检测和ASDF的时延估计方法,对ASDF统计量进行插值以达到分数延迟的估计精度。仿真实验和实际测试表明,该方法完全可以作为超声窄带信号时延统计量。此外,可以有效地避免噪声对ASDF统计量全局极值偏移的影响,并可极大地减少运算量,满足实际应用的要求。

Time delay estimation （TDE） methods for narrowband ultrasonic signals are studied in the background of ultrasonic measurement. In practice application, the TDE methods should be adapted to the situation of low SNR with high accuracy and low computation load. In the re- search, an average square difference function （ASDF） time delay estimator is chosen for nar- rowband ultrasonic signals. And the performance of ASDF is analyzed indetail. For the effect of noise on the ASDF estimator, a new method using gravity center of signals together with ASDF is introduced. Besides, sub-sample interval resolution is achieved by the interpolation of ASDF estimator. Numerical simulations and actual experiments exhibit that the proposed method can be totally used as a good time delay estimator for ultrasonic narrowband signals. Together with the detection of signal gravity center, the global extreme confusion with other local extremes can be avoided. Moreover, the calculation load can be also reduced, which makes it suitable for application in practice.