Weak signal detection method of adaptive digital lock-in amplifier based on particle swarm optimization algorithm

In this paper, an intelligent algorithm - particle swarm optimization (PSO) is applied to adaptively realize weak sinusoidal signal detection of digital lock-in amplifier. Each particle is a reference signal. Using this algorithm PSO first searches the optimum particle of particle swarm, and then estimates the corresponding parameters of input useful signal through the messages of the optimum particle. The algorithm can realize detection of weak signal by modifying its some parameters, so it is more convenient and flexible than the method of traditional lock-in amplifier (LIA) in application. Computer simulation results show that this method can accurately detect multiple useful sinusoidal signals which are inundated by strong noise of -40 dB, and also detect AM signal. Then the effectiveness of this method is verified by AM signal.