We improved the performance of a functional near-infrared spectroscopy (fNIRS)-based brain–computer interface based on relatively short task duration and multiclass classification. A custom-built eight-channel fNIRS system was used over the motor cortex areas in both hemispheres to measure the hemodynamic responses evoked by four different motor tasks (overt execution of arm lifting and knee extension for both sides) instead of finger tapping. The hemodynamic responses were classified using the naive Bayes classifier. Among the mean, max, slope, variance, and median of the signal amplitude and the time lag of the signal, several signal features are chosen to obtain highest classification accuracy. Ten runs of threefold cross-validation were conducted, which yielded classification accuracies of 87.1%±2.4% to 95.5%±2.4%, 77.5%±1.9% to 92.4%±3.2%, and 73.8%±3.5% to 91.5%±1.4% for the binary, ternary, and quaternary classifications, respectively. Eight seconds of task duration for obtaining sufficient quaternary classification accuracy was suggested. The bit transfer rate per minute (BPM) based on the quaternary classification accuracy was investigated. A BPM can be achieved from 2.81 to 5.40 bits/min.
This paper describes the transmission performance of the 10Gb/s phase-modulated (PM) duobinary modulation format, compared with the conventional duobinary modulation format using a low-pass filter (LPF) in cascaded optical networks. We theoretically investigate the transmission characteristics of both modulation formats with considering the effect of narrowing bandwidth of multiplexers (MUX) and demultiplexers (DEMUX) at cascaded nodes with different fiber launching powers (FLP). It's shown that PM duobinary signals, at the FLP of 9dBm, can be transmitted over 3 nodes (up to a distance of 1,200km) with only 1.25dB power penalty.
This paper describes the simulation approach of the improvement of dispersion tolerance for an electrical-binary-signalbased duobinary transmitter. We can transmit the duobinary signals over 200 km of singe-mode fiber by optimizing the relative time delay and the driving voltage.
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