基于数字锁相相关计算结构的优化算法

为了兼顾数字锁相检测的速度和精度，提高信号检测系统的综合性能，该文提出了一种基于数字锁相相关计算结构的高速算法并结合过采样对算法性能优化。该方法在过采样的基础上将采样频率还原为4倍于原信号的频率，快速数字锁相算法对下抽样后q个周期的4q个采样点进行加减法运算即可实现，与传统数字锁相算法相比几乎消除了所有的乘法运算，大幅度地提高了数字锁相算法实现的速度。同时引入修正因子改善了由于降采样所带来的误差。实验结果表明，该方法既有过采样和锁相检测的高精度，能够检测到较低信噪比的信号，又具备较高的速度，使得该算法对微弱信号的实时检测在普通微处理器上的实现成为可能。

An Optimization Algorithm Based on Computation Structure of Correlation in Digital Lock-in Detection

In order to give consideration to both of the precision and speed to improve the comprehensive properties of the detecting system,a new high-speed algorithm is proposed based on computation structure of correlation in digital lock-in detection and it is optimized by oversampling.The algorithm based on oversampling reduces the sampling frequency to four times of the frequency of an input signal.Thus,the digital lock-in algorithm can be implemented by the addition and subtraction operations of 4q points in q periods.This process eliminates almost all the multiplication operations compared with the traditional method.And the speed of the digital lock-in algorithm is greatly enhanced.Moreover,a correction factor is introduced to improve the error caused by down-sampling.The results of the experiments show that the new algorithm not only has high precision of oversampling and digital lock-in detection for signal with low signal-to-noise ratio,but also has high speed,which makes it possible for a general microprocessor to implement weak signal detection by the new algorithm in real time.