Real-time particle size and charge estimation from laser Doppler burst signals using Quadrature Demodulation and correlation techniques

This paper describes an integrated signal processing system based on Quadrature Demodulation (QD) and correlation techniques to obtain particle size and charge simultaneously using phase Doppler anemometry (PDA). By solving the equation of particle motion in an AC electric field combined with the measurement of its size and velocity, the magnitude as well as the polarity of the particle charge can be obtained. The Matlab Simulink models of the signal processing system have been implemented and tested on the particle with velocity amplitude approximately from 16 mm/s to 550 mm/s. The corresponding charge measurement range is from several electrons to the saturation level.