Abstract:Rough alignment process of Strapdown Inertial Navigation System is the premise of realizing accurate initial alignment and the guarantee of accurate navigationg and positioning. Influenced by the external environment, rough alignment process has some problems such as long time and low accuracy. The time and accuracy of initial alignment process are also affected. By analyzing the interference factors of gyroscope and accelerometer in rough alignment process, a hybrid filtering method combining median filtering and wavelet threshold filtering is adopted to realize signal denoising. Simulation and experiments show that under the premise of serious external interference, the standard deviation of rough alignment azimuth angle is increased from 47° to 1.588° by using the hybrid filtering method. It provides better data support for the subsequent precision alignment process, the alignment time is shortened and the rapid response ability of the equipment is improved.