一种基于PC总线的多功能数字卡的实现

Implementation of a Kind of Digital Multi-function Card Based on PC Bus

针对远程信号监测系统对测控仪器的要求,文中给出了在ISA卡上集成高精度频率计/信号源的设计原理与实现方法.该设计采用CPLD电路,对恒温晶振的输出信号和GPS的PPS信号进行自适应处理,克服了在实际应用中GPS秒脉冲信号易受干扰、晶振存在不确定漂移等因素造成的误差,将获得的高精度时钟信号和GPS秒脉冲信号作为基准信号用在测频电路和信号源中,使频率计和信号源可以长时间保持很高的精度,提高了系统的性能和可靠性.

In this paper, a design principle and implementing method are given to get a kind of digital multi-function card, which load-bearing a signal source and digital cymometer with high precision. According to the adaptive control principle, the output of OCOX and PPS controlled by the circuits are built in CPLD. It can overcome the error brought by the interference pulse and the frequency drift caused by the OCOX and get sync source with high precision and precise frequency, which can been used in the frequency measurement circuit as the reference signal. By using it, the card can keep high precision for a long time and improve the performance and reliability.