基于LPC1788的AMI码解码电路的设计与实现

Design and Implementation of AMI Decoder Circuit Based on LPC1788

针对目前生产测井仪器种类多、编码方式各异的特点,设计了一款基于LPC1788的地面接收卡。在详细介绍AMI码型、帧数据格式的基础上,重点阐述板卡的信道均衡、自动增益调整等硬件电路设计和AMI码的解码时序。根据码型特点,对长连零情形下的误码原因进行剖析,通过采用响应速度更快的ARM芯片、优化解码时序,消除了位累积时钟偏差,有效地降低了误码率。在某油田生产井的应用实践表明,该板卡性能稳定、使用灵活、兼容性强,能够满足生产测井对于数据传输的需求,进一步扩展了SKD3000数控测井仪的应用范围。

Aiming at the characteristics of current production well tools and various coding methods,a surface receiving circuit based on LPC1788 is designed. On the basis of the detailed introduction of AMI pattern and its frame format,the hardware circuit design,such as channel equalization and automatic gain adjustment,and the decoding timing of the AMI code are mainly elaborated. According to the characteristics of AMI code,the cause of error is analyzed in the case of decoding continuous zero. By optimizing the decode timing and applying ARM,the accumulated deviation of bit clock is greatly eliminated and therefore the decoding BER becomes much lower. The application practice in production well of an oilfield demonstrates that the circuit presents some characteristics of stable,flexible and strong compatibility and can meet the demand of data transformation for production well logging,which further expands the application range of SKD3000.