Time-Frequency Characteristic Analysis For Human Pulse Signals

Traditional Chinese medicine has received world's wonder for its unique diagnostic methods and particularly curative effects. Along with the development of sensors and computer technology, people hope to apply modern technology to human pulse diagnosis, in order to reveal the essence and features of pulse's phenomena scientifically and objectively, which is the main research aspect in this dissertation.Short-time Fourier transform (STFT) and Gabor expansion are the two analytical methods which are earliest and most commonly used in the time-frequency representation of signals. The continuous short-time power spectrum represents the energy distribution of a signalon the plane with continuous time and frequency. However, the discrete short-time power spectrum represents the power distribution of a signalon the plane with discrete time and continuous frequency. In this dissertation, an efficient recursive algorithm with all-pole moving-windows is used to analyze the discrete short-time power spectra of pulse signals for 15 heroin addicts and 15 healthy persons. According to three-dimensional figure and contour map, it is found that the average powerof heroin addicts on a specified time-frequency region is generally higher than that of healthy persons. This dissertation computes the average powerof every pulse signal on a specified time-frequency region and total average power. Using the ratio of average powerto total average poweras characteristic parameter, a critical parameter is determined that is used to classify heroin addicts and healthy persons. Thus, all of the 15 heroin addicts are identified. Only two healthy persons are misjudged. The Gabor coefficienton a specific time-frequency grid point can mark the time-frequency characteristic of the signal, which is related to this point. This dissertation computes the Gabor coefficients of pulse signals for 15 heroin addicts and 15 healthy persons based on discrete Zak transform (DZT). By means of the three-dimensional and contour maps of the , it is found that there is the significant difference between the heroin addicts and the healthy persons at some time-frequency grid points. Using the sum of at given time-frequency grid points as characteristic parameter, a primary criterion is obtained, upon which the 15 heroinaddicts are identified and 3 healthy persons are misjudged. It is shown that at the aspect of extracting characteristic information of pulse signals, the STFT has superiority over Gabor expansion.This dissertation also researches and deduces the definitions and formulas of the STFT and Gabor expansion, and reasonably explains the physical meaning of the discrete short-time power spectrum. While using the STFT and Gabor expansion to analyse pulse signals, this dissertation also modifies, verifies and uses modificatory algorithm.