Digital Lock-in Algorithm for Biomedical Spectroscopy and Imaging Instruments with Multiple Modulated Sources

• Published in: 2006 International Conference of the IEEE Engineering in Medicine and Biology Society Vol. 2006; pp. 3198 - 3201
• Main Authors: Masciotti, J.M., Lasker, J.M., Hielscher, A.H.
• Format: Conference Proceeding Journal Article
• Language: English
• Published: United States IEEE 2006
• Subjects: Algorithms; Amplitude modulation; Biomedical Engineering; Biomedical imaging; Biomedical measurements; Diagnostic Imaging - instrumentation; Diagnostic Imaging - statistics & numerical data; Digital modulation; Instruments; Noise measurement; Phase modulation; Sampling methods; Signal Processing, Computer-Assisted; Signal to noise ratio; Spectroscopy; Spectrum Analysis - instrumentation; Spectrum Analysis - statistics & numerical data
• ISBN: 9781424400324; 1424400325
• ISSN: 1557-170X
• DOI: 10.1109/IEMBS.2006.259303

Digital lock-in detection provides spectroscopic and imaging instruments a means of measuring physical quantities with improved signal to noise ratios compared to analogue detection schemes. We introduce a digital lock-in detection algorithm for measuring the amplitude and phase of multiple amplitude modulated signals simultaneously by using particular modulation and sampling constraints and averaging filters. The technique exhibits exceptional reduction in both noise and inter-source distortion. It is shown that the digital lock-in technique can be performed as a simple matrix multiplication in order to reduce computation time. The digital lock-in algorithm is described and analyzed under certain sampling and modulation conditions. Results are shown for experimental data