Study of Filter Used in Revolution-Modulation North-Finder

In order to improve the precision of the north-finder, a method of continuous revolution in constant rate to modulate the signals of the gyro and accelerometer is used, and the signals can be demodulated by an integral method. Thus, the effects of the gyro's constant drift and low frequency part of random drift are restrained. A low-pass filter is designed to eliminate high frequency disturbance caused by mechanical rotation and gyro noise. Experiment results show that these two measures can increase the precision of the north-finder.