高精度LINS陀螺采样频率以及噪声抑制技术

Gyro sample frequency and noise restraint methods in a high-precision laser INS

基于激光陀螺高带宽和数字化输出的特点,提出激光陀螺数字信号处理的两个基础性问题,采样频率合理性与抗混叠滤波。分析了国产高精度激光捷联惯导常用的2000 Hz采样频率下激光陀螺频谱特性。指出在该采样频率下,激光陀螺输出信号中存在某些固定频率干扰信号。提出一种逐步升高采样频率的方法,给出了谱峰位置确定公式,证明国产高精度激光陀螺输出信号中存在机抖频率的3倍频和5倍频干扰信号,并给出合理的最低采样频率应为4500 Hz。为了解决激光陀螺数字化输出的抗混叠滤波问题,建议引入过采样技术,继续提高采样频率,降低激光陀螺功率谱密度,并利用低通滤波抑制噪声,提高激光陀螺精度。

Based on the characteristics of laser gyro＇s high bandwidth and digital output,two basic problems in laser gyro digital signal processing are put forward,i.e. rational sampling frequency and anti-aliasing filter. The laser gyro spectrum characteristics in domestic high-precision laser strapdown inertial navigation are analyzed,and it is found that there are some fixed frequency jamming signals in the laser gyro output at 2000 Hz sampling frequency. A noise restraint method is put forward by gradually increasing sampling frequency to locate spectrum peak position,and the frequency calculation formulas are given. It is verified that there are 3 times and 5 times of dithering frequency interference signals in laser gyro output signal by using these formulas. The domestic high-precision laser gyro＇s reasonable minimum sampling frequency is given,which should be 4500 Hz at least. In order to solve the problem of anti-aliasing filter,an oversampling technology should be used to reduce the power density of the laser gyro in frequency field. Meanwhile the low-pass filter should be employed to restrain noises and improve the laser gyro＇s accuracy.