Lock-in technique for extraction of pulse rates and associated confidence levels from video.

We investigate the practical applicability of video photoplethysmography (VPPG) to extract heart rates of subjects using noncontact color video recordings of human faces collected under typical indoor laboratory conditions using commercial video cameras. Videos were processed following three previously described simple VPPG algorithms to produce a time-varying plethysmographic signal. These time signals were then analyzed using, to the best of our knowledge, a novel, lock-in algorithm that was developed to extract the pulsatile frequency component. A protocol to associate confidence estimates for the extracted heart rates for each video stream is presented. Results indicate that the difference between heart rates extracted using the lock-in technique and gold-standard measurements, for videos with high-confidence metrics, was less than 4 beats per minute. Constraints on video acquisition and processing, including natural subject motion and the total duration of video recorded required for evaluating these confidence metrics, are discussed.

Nonlinear filter based decision feedback equalizer for optical communication systems.

Nonlinear impairments in optical communication system have become a major concern of optical engineers. In this paper, we demonstrate that utilizing a nonlinear filter based Decision Feedback Equalizer (DFE) with error detection capability can deliver a better performance compared with the conventional linear filter based DFE. The proposed algorithms are tested in simulation using a coherent 100 Gb/sec 16-QAM optical communication system in a legacy optical network setting.

Michelson interferometer based interleaver design using classic IIR filter decomposition.

An elegant method to design a Michelson interferometer based interleaver using a classic infinite impulse response (IIR) filter such as Butterworth, Chebyshev, and elliptic filters as a starting point are presented. The proposed design method allows engineers to design a Michelson interferometer based interleaver from specifications seamlessly. Simulation results are presented to demonstrate the validity of the proposed design method.