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提出了一种利用软件算法来自适应地实现数字锁定放大器的微弱正弦信号的检测,即利用稀疏分解的匹配追踪算法来实现这种检测方法.将稀疏分解中原子库的原子(即具有随机性的频率和初始相位的正弦波)作为参考信号,利用匹配追踪算法来搜索原子库(由多个原子组成)中的最优原子——即与输入有用信号最匹配相干的原子并可以得到该最优原子的幅度,由该最优原子的幅度、频率和初始相位信息就可以估计得到输入有用信号的对应参数,从而检测估计出输入信号中的有用正弦信号.该方法无需人工调节参考信号的幅度、频率和初始相位,只需修改算法中的某些参数即可实现微弱信号检测,在应用中就会更加方便、灵活.计算机模拟表明,可以精确地检测出带噪信号中有用的正弦信号和调幅AM信号,并且在-40 dB以下极低信噪比环境下还可以同时检测出多个被强噪声淹没的有用正弦信号.
This paper presents a detection algorithm of weak sinusoidal signal by using software algorithm to adaptively realize digital lock-in amplifier, that is, using the sparse decomposition matching pursuit algorithm to realize this detection method.At the same time, Frequency, and initial phase) as a reference signal, a matching pursuit algorithm is used to search for the optimal atom in the atomic library (made up of multiple atoms) - the atom that most closely matches the input useful signal - and can get that optimal The amplitude of the atom, the frequency and the initial phase information of the optimal atom, the corresponding parameters of the input useful signal can be estimated to detect and estimate the useful sinusoidal signal in the input signal.This method does not need to manually adjust the amplitude of the reference signal, Frequency and initial phase, only some parameters in the algorithm can be modified to achieve weak signal detection, and it is more convenient and flexible in application.Computer simulation shows that it is possible to accurately detect the useful sinusoidal signal and amplitude modulation in the noisy signal AM signal, and in the extremely low signal-to-noise ratio environment below -40 dB can also be detected at the same time a number of strong noise Useful sinusoidal signal flooded.