A band pass filter allows the energy concentrated between two given frequencies (X and Y) to pass while it attenuates the signal's energy at other frequencies. It is equivalent to applying a high-pass filter at X and a low pass filter at Y.
A band stop filter attenuates the energy in the frequencies between two given frequencies (X and Y). It is equivalent to applying a low pass
filter at X and a high pass filter at Y.
Note that filters do not remove all of the energy outside of their pass band (the pass band is the frequencies between X and Y for a band pass filter, and below X and above Y for a band stop filter). Generally, the further away from the cut off frequencies (X and Y), the greater the attenuation of the energy. How fast the attenuation increases as a function of frequency is established by parameters (primarily “Q”) of the filter. Real filters will also attenuate within the pass band, and there are some tradeoffs in the selection of parameters.
fNIR Imaging Systems are stand-alone functional brain imaging solutions for continuous NIR spectroscopy (NIRS). They provide an in-lab cognitive function assessment and eliminate a great many of the drawbacks of a functional MRI. fNIR optical imaging technology measures neural activity and hemodynamic response in the prefrontal cortex. Subjects wear an fNIR sensor (IR light sources […]
BIOPAC co-founder and R&D Director, Alan Macy, was interviewed recently by Roger Durling for the Santa Barbara Independent. The article, “The S.B. Questionnaire: Alan Macy,” provided a background excerpt of the Santa Barbara entrepreneurs’ past as well as his answers to the Proust Questionnaire. The biomedical technology developed at BIOPAC reflects an ambitious understanding of the natural and […]
Physiological researchers have been studying the lower body through examining impacts of training, movement instruction, and innovative research measurements on an individual’s well being. The following articles represent recent developments in physiological research, moving our understanding of lower limbs and the body as a whole forward, one step at a time. The Importance of Form Improper […]