title: Fast digital lock-in amplifier for dynamic spectrum extraction.
abstract: An appropriate method for spectrum extraction for better signal-to-noise ratio (SNR) and lower computational cost is essential in noninvasive detection. We have first studied two existing extraction methods for dynamic spectrum (DS) comparatively: frequency domain analysis and single trial estimation; after analyzing the advantages and disadvantages theoretically, a new method based on a fast digital lock-in amplifier (FDLIA) was developed to overcome the limitations of these two existing methods. The feasibility of the new method was verified by experiments and the results demonstrated that the FDLIA method based on DS had greatly simplified the computation of frequency domain analysis without the method error; moreover, the continuous signal was cut into several short segments in FDLIA and the gross errors from an episode of pulse wave were eliminated, and thus SNR improved. Therefore, the FDLIA method utilizing the advantages of both existing methods can be effectively realized in a general embedded system in real time for its simple algorithm.
authors: Tianjin University, School of Precision Instrument and Opto-Electronics Engineering, Tianjin 300072, China.
authors: Mei
authors: M
authors: Zhou
authors: Gang
authors: G
authors: Li
authors: Ling
authors: L
authors: Lin
mesh_terms: D003198:Computer Simulation; D005240:Feasibility Studies; D005260:Female; D005336:Fiber Optic Technology / Q000295:instrumentation; D005385:Fingers / Q000098:blood supply*; D006801:Humans; D008962:Models, Theoretical; D061848:Optical Imaging / Q000295:instrumentation / Q000379:methods*; D010100:Oxygen / Q000097:blood; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation*; D059629:Signal-To-Noise Ratio; D013057:Spectrum Analysis / Q000295:instrumentation / Q000379:methods*
chemical_list: D010100:Oxygen