Real-Time Lock-In Amplifier Implementation Using a Kalman Filter for Quasi-Periodic Signal Processing in Fusion Plasma Diagnostics

The prospects for the real-time amplitude estimation of selected harmonic components of quasi-periodic signals from a motional Stark effect (MSE) tokamak plasma diagnostic is addressed using Kalman filtering techniques. The proposed method is shown to be more competitive than a standard low-pass filter lock-in amplifier scheme. In particular, when block data processing is limited to a small number of samples signal harmonics are narrowly separated in frequency or in the presence of frequency jitter, the superior competencies of the Kalman filtering method are evidenced.