频谱混叠对光纤陀螺振动特性测试的影响

Influence of frequency mixing on vibration test of fiber optic gyroscope

振动过程中的频谱混叠会使光纤陀螺中采样后信号相对于原信号产生失真现象,从而影响测试结果.为了验证频谱混叠带来的影响,并进一步抑制频谱混叠现象的发生,设计实现了一套用于获取光纤陀螺原始输出的闭环数据采集系统(速率可达1 MHz×16 bit),分析了振动测试过程中光纤陀螺闭环数据的特征,发现目前光纤陀螺中常用滤波器无法有效滤除闭环数据中振动成分,因此可能会由于采样频率设置不当引起频谱混叠;通过matlab仿真和陀螺振动实验对频谱混叠造成的影响进行了验证;针对频谱混叠现象提出了抑制措施.实验结果表明对于采用类似数据采集过程的光纤陀螺,改进后的设计可以有效避免频谱混叠现象的发生.

Frequency mixing happening in vibration test on fiber optic gyroscope （FOG） can cause signal distortion of the output of FOG, which will influence the test result. In order to verify the consequence of fre quency mixing and restrain it, a closed-loop data acquisition system which was used to get the original output of FOG （namely closed-loop data） was designed and realized （the speed could reach 1 MHz x 16 bit）. The character of closed-loop data in vibration test was analyzed and the fact that the vibration error could not be wiped out by filter was known, which would cause frequency mixing if the sampling frequency was not proper. The frequency mixing was verified through simulation by matlab and vibration test on FOG. The restraining method of frequency mixing was given. Experiments show that for the FOG whose data acquisition process was designed as what was referred, the design improved could avoid frequency mixing very well.