Electrocardiogram in survey process frequently easily by many noise disturbances, and these noise will often affect the electrocardiogram the diagnosis or let the feature extract have a difficulty. Therefore we using the first part of Hilbert - Huang transform (HHT), the empirical mode decomposition (EMD) to filter the noise. In the process, we discovered that the filter of EMD method will sacrifice a part of the low frequency ingredient. So, we try to use the ensemble empirical mode decomposition (EEMD) to as the filter. And makes the error by Signal-to-Error Ratio (SER) to estimate, finally the effect of EEMD method indeed surpasses the EMD method and also better than traditional Butterworth filter. After completing the electrocardiogram filter processing we calculate pulse transit time (PTT). We try to develop some new PTT derivation parameter from PTT, applying the parameter in the experiment of Leg-Crossing. Compared with the HRV parameter and the PTT derivation parameter, discovered that the PTT derivation parameter to have more differences than the HRV parameter in posture change. When posture change, the HRV parameter only the RRI has difference (P<0.05), But in PTT derivation parameter PTT, PTT_SDNN, PTT_SD2, PTT_HF all have the obvious difference (P<0.05). This result showed that PTT more suitable to HRV in the posture change research. In future may apply the PTT derivation parameter to the broader range of study, we believed that can obtain more interesting discoveries surely.
