采用多周期测量原理，即用标准频率信号填充整数个周期的被测信号，从而消除了被测信 号+1的计数误差，其测量精度仅与门控时间和标准频率有关，克服传统的直接测频或者直 接测周法均不能全面满足高精度要求的缺陷-Using the principle of multi-cycle measurements, i.e. integer number of cycles of the measured signal is filled with a standard frequency signa