毕业论文对于频率的测量,常用的方法有直接测频法和测周法.直接测频法是通过测量标准闸门时间内待测信号的脉冲数而计算出待测信号频率的,由于闸门时间通常不是待测信号周期的整数倍,因此存在最大±1的待测信号脉冲误差,只能在信号频率较高时采用 测周法是通过测量待测信号的周期并求其倒数而求得其频率的,在待测信号的一个周期内也存在最大±1的标准信号脉冲误差,只能在信号频率较低时采用.这两种频率测量方法都存在局限性,并难以实现宽频带、高精度测量-Thesis for the frequency of measurements, commonly used method of direct frequency measurement method and measured weekly law. Direct frequency measurement method is the standard by measuring the time the gate pulse signals under test to calculate the number of the analyte signal frequency, because of the gate usually the signal under test is not an integer multiple of the cycle, so there is the largest ± 1 of the analyte signal pulse error can only be used in the high frequency signal　measurement method is by measuring the weeks under test signal cycle and seek their penultimate and obtained his frequency in the signal under test cycle, there are a maximum ± 1 standard error of the signal pulse can only be used in the signal frequency is low. Both the frequency measurements are limited, and difficult to achieve broadband, high- precision measurement