DEMODULATING A SIGNAL FROM INTERMITTENTLY ILLUMINATED REGION

A system may intermittently illuminate a region, detect light from the intermittently illuminated region to form a detected signal, and process the detected signal with a demodulator. The demodulator may include a capacitor having an input to receive the detected signal, a resistor having an input c...

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Bibliographic Details
Main Authors Seitz, Jason M, Pickett, Matthew D
Format Patent
LanguageEnglish
Published 20.08.2020
Subjects
DIAGNOSIS
HUMAN NECESSITIES
HYGIENE
IDENTIFICATION
MEDICAL OR VETERINARY SCIENCE
SURGERY
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Summary:A system may intermittently illuminate a region, detect light from the intermittently illuminated region to form a detected signal, and process the detected signal with a demodulator. The demodulator may include a capacitor having an input to receive the detected signal, a resistor having an input connected to an output of the capacitor at a connection point, and a switch that connects the connection point to ground during times when the region is not illuminated. An output of the resistor may produce an output signal that is a high-pass filtered version of the detected signal during times when the region is illuminated, and a time-invariant ground signal during times when the region is not illuminated. Such a demodulator may reduce the effects of low-frequency noise sources, such as background light, op-amp offsets related to input bias, photodiode 1/f noise and dark current.
Bibliography:Application Number: US201516061509