《PlayDemoandLearnSignalProcessing.docVIP

Play Demo and Learn Signal Processing - Bispectrum and Bicoherence 版本 6? 创建于: 2009-7-7 上午4:43 作者 Macpac - 最后修改:? 2009-7-8 上午3:02 作者 Macpac ? This document includes a fundamental overview for the concept of bispectrum and bicoherence, and also attaches a LabVIEW demo to help you understand the concepts. ? Bispectrum is a kind of high-order spectrum.? It is an analysis tool to detect whether the phase of signal components at frequency f1, f2 and f1+f2 are coupled or interdependent. For example, you can use the attached demo to simulate the signal that contains frequency f1, f2 and f3 with different phase configuration: ? ? Configuration #1 (f3 != f1 + f2, phase NOT coupled): f1 = 6Hz, f2 = 4Hz, f3 = 9Hz, theta 1, theta 2 and theta 3 are all random. Configuration #2 (f3 != f1 + f2, phase coupled) : f1 = 6Hz, f2 = 4Hz, f3 = 9Hz, theta 3 = theta 1 + theta 2. ? Configuration #3 (f3 = f1 + f2, phase NOT coupled): f1 = 6Hz, f2 = 4Hz, f3 = 10Hz, theta 1, theta 2 and theta 3 are all random. Configuration #4 (f3 = f1 + f2, phase coupled) : f1 = 6Hz, f2 = 4Hz, f3 = 10Hz, theta 3 = theta 1 + theta 2. Only configuration #4 shows a peak at (f1, f2) in the bispectrum.? There are no significant large values at the bispectrum of the other configurations.? These results show that bispectrum can be used to detect whether a signal contains nonlinear components at frequency f1 + f2 whose phase is coupled to the phase of components at fequency f1 and f2.? There is no obvious difference between the power spectrum of #3 and #4, which means power spectrum cannot tell whether there are phase couple between frequency components. ? Phase couple is typical in nonlinear system.? For example, one simple nonlinear system is a system whose output is the square of its input.? When you apply the following signal to the system the output of the systm will be: The nonlinear system generates new frequency components whose phases are coupled with the phase of the input components. ? EEG si