Design Of Digital Lock-In Amplifier Based On DSP

The weak signal detection technology is a new developing discipline which develops unceasingly with the project application; detect the weak signal that are marked by noise. Along with social and the technical development, The weak signal detection technology already obtained quite widespread application in physical, chemistry, the astronomy, biological, the medicine as well as the many kinds of projects application domain. By the same time, the equipment used to detect weak signal is developing and become grandness gradually. Between them, The lock-in amplifier (LIA) has become the main instrument of current weak signal detection with its low power loss and the higher reliable prominent characteristic, and has applied widely in the military national defense> the domestic electric appliances^ the network communication> the industry control and so on.This article first introduced the weak signal detection methods the detection principle. Expounding the work principle of the traditional analog LIA (ALIA) and the digital LIA (DLIA) applied widely nowadays, and has contrasted them two, analyzed the limitation and complexity of the ALIA and the advantage of the DLIA, And then proposed the design plan of the DLIA based on the DSP technical. In order to satisfy the quick operating speed, strong timeliness, the higher request precision, we have selected TI Corporation's DSP chip TMS320C5416 as the core carry on the system design. Based on the DLIA correlation detection principle, produce the DLIA overall design, emphatically from the realization of correlation detection and table look-up algorithm by the software,we has made the detail analysis design, simulated the correlation detection algorithm by MATLAB, compared the quality of the used signal that has detected in different SNR conditions, validated the feasibility of the algorithm. Finally, realized the core algorithm design based on DSP chip on C language programmed.