瞬变电磁仪高精度GPS时钟同步的研究  

Research on high-accuracy GPS-time synchronization in transient electromagnetic machine

作　　者：姬智艳[1] 邓维克[2] 苏娟[1] 曹达[1] 黄龙 

机构地区：[1]湖南大学电气与信息工程学院,湖南长沙410082 [2]邵阳学院,湖南邵阳422000 [3]长沙五维地科勘察技术有限公司,湖南长沙410205

出　　处：《电源技术》2014年第1期145-148,164,共5页Chinese Journal of Power Sources

摘　　要：瞬变电磁仪是一种重要的地质勘探仪器。为了提高瞬变电磁仪的同步精度,针对恒温晶振长期稳定性差和GPS短期稳定性差的问题,提出一种基于嵌入式微处理器STM32F407、GPS接收模块、中等精度恒温晶振的瞬变电磁仪GPS时钟同步方法。在分析瞬变电磁仪系统组成及GPS同步的工作原理的基础上,利用STM32F407能够灵活输出PWM的特点,通过获取恒温晶振的实际工作频率后,设置STM32F407计数器的相关寄存器输出同步的PWM作为同步控制时序,同步瞬变电磁仪的发送机和接收机。采用卡尔曼滤波克服了1PPS信号短期抖动性,充分考虑到GPS存在短期失锁的问题,结合IIR滤波、最小二乘算法,分别设计了GPS锁存状态和失锁状态的同步实现方法。实验结果表明,开机30 s后,系统的同步精度达到0.01 ms,在GPS短期失锁时仍能保持0.01 ms的精度。Transient electromagnetic machine is an important instrument for geological exploration. In order to improve the synchronization accuracy of transient electromagnetic machine and solve the problems of poor long-term stability of constant temperature crystal-oscillator and short-term stability of GPS, a kind of GPS-time synchronization method of transient electromagnetic machine base on the embedded microprocessor STM32F407, GPS receiver module and medium-accuracy constant temperature crystal-oscillator was proposed. The composition of transient electromagnetic machine and the principle of GPS synchronization were analyzed, PWM as synchronous control timing to synchronize the transmitter was used; transient electromagnetic machine by setting the relevant register of STM32F407 counter was received; then the obtaining the actual frequency of constant temperature crystal-oscillator, the transmitter and receiver of transient electromagnetic apparatus were in-phase.Short-term jitter of the 1PPS signal was conquered by Kalman filtering algorithm.Combination of IIR filtering,least squares algorithm,the synchronization methods under the GPS-Iock state and the GPS-unlock state were designed by taking fully into account to the existence of short-term GPS-unlock state. The experimental results show that the synchronization accuracy of the system reaches 0.01 μs after 30 s, which is able to keep with 0.01 μs under short-term GPS-unlock state.

关 键 词：瞬变电磁仪 GPS同步 卡尔曼滤波 IIR滤波 最小二乘法 

分 类 号：TM154[电气工程—电工理论与新技术]