摘要： 为提高数字锁相放大器的最大调制频率,并同时快速检测双频复合信号,提出一种基于方波参考的快速数字锁相算法。该算法设置四路参考信号,其中两路为频率为f的正交参考信号,两路为频率为2f的正交参考信号。设置两个调制频率分别为(2a-1)f和(4b-2)f,同时对平均滤波器的长度进行设置,避免通道之间产生干扰。试验表明,该算法能同时检测双频复合信号中每个分量的幅值和相位,且幅值误差小于0.7%,相位误差小于0.5%。相敏检波过程中的乘法运算被加法和减法替代,提高数字锁相算法的运算速度,有效扩大锁相放大器的检测带宽。 Abstract: In order to increase the maximum modulation frequency of digital lock-in amplifier and detect dual-frequency composite signal simultaneously, a fast digital lock-in algorithm based on square wave reference was proposed. There were four reference signals with frequencies of f and 2f respectively. Two modulation frequencies were set to (2a-1)f and ((4b-2)f respectively, and limited the length of the average filter to avoid interference between the channels. The results of the experiments showed that the proposed algorithm could detect the amplitude and phase of each frequency component of the input signal, and the errors of the amplitudes were less than 0.7% and the errors of the phase were less than 0.5%. It replaced the multiplication by additions and subtractions in the phase-sensitive detection improved the speed of the digital lock-in amplifier and effectively expanded the detection bandwidth of the lock-in amplifier
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