针对高精度的频率测量,分析了相位检测法的测量误差,根据分析结果提出并实现了一种基于FP—GA实现的频率测量方法。该方法利用FPGA器件门时延小、电路稳定的特性,采用相位重合检测的改进方法,降低了测量时的±1计数误差。对其进行的误差分析表明,其测量精度约为10^11/r量级。研制样机的实际测量数据表明,该方法满足高精度、低成本的频率测量要求,具有大规模推广应用价值。
To investigate high-accuracy frequency measurement, the measurement error of the phase detection method is analyzed. According to the analyse results, a method based on FPGA technology is proposed and implemented. Utilizing the characteristics of shorter delay of internal gates and more stabilizable circuit in FPGA, the 4-1 count error is reduced. The error analysis shows that its accuracy is approximately 10 ^11/r order of magnitude. The actual measurement data show that the method meets the requirement of high-accuracy and low cost frequency measurement. It is feasible to be applied widely.