Interference Signal Acquisition And Processing Based On

With the theoretical research on the laser self-mixing interference (SMI) technology becoming increasingly mature, it has been widely used in vibration and micro-displacement measurement. The basic requirement of this technology is real-time acquisition and processing of the self-mixing interference signal. The structure of traditional data acquisition and processing system is complicated, expensive and unwieldy. In contrast, owing to its high speed performance and high-precision computing, the digital signal processor (DSP) serves to be more suitable for the acquisition and processing of laser self-mixing interference signals.The characteristics of a laser self-mixing interference signal with triangular current modulation and the principle of the vibration measurement and the algorithm for reconstructing the vibration waveform were researched in this paper. The hardware design and implementation of the system is detailed. TMS320F2812A from Texas Instruments (TI) is used as the core processor. The hardware system is composed of the minimum system of DSP, DSP and ADC interface circuit, signal conditioning circuit and the DSP interface circuit, RS232 communications circuit, etc. The system software design is implemented in CCS3.3 development environment to realize the signal acquisition and preprocessing and FFT transform. The processed data is displayed by MATLAB through the serial port. The acquisition and preprocessing of the laser self-mixing interference signal and the reconstruction of vibration waveform are achieved in this paper.It’s verified that DSP signal processing board performs well in reconstructing the vibration waveform of detected objects. By using the DSP technology, the cost of system is greatly reduced and the structure of system is simplified. Based on this, more in-depth research can be done in future.