Patent ID: 9730644
Date: 2017-08-15
CPC Classifications: A61B

Claim:
1. A method for processing a detected light signal, comprising a photoplethysmographic (PPG) signal, in a monitoring device to measure properties of blood flow, the method comprising: receiving a mode selection signal that specifies between at least a first mode of operation of the monitoring device and a second mode of operation of the monitoring device; operating a switching component to select between at least a first light source when the mode selection signal specifies the first mode of operation and a second light source when the mode selection signal specifies the second mode of operation; operating a selected one of the first light source and the second light source, as selected by the switching component, to generate a source light signal; obtaining a first digital signal representing a detected light signal from the selected light source after the source light signal interacts with a skin tissue; generating a second digital signal from the first digital signal based at least in part on the selected mode of operation; providing the second digital signal to a processor, the processor measuring a selected one of the properties of blood flow in accordance with the selected mode of operation; and generating an offset control signal from an estimation of a non-pulsatile component of the first digital signal, wherein, in the first mode of operation: (i) the offset control signal is set to zero; or (ii) one or more components generating the offset control signal are disabled, and wherein, in the second mode of operation, the second digital signal is generated by subtracting a voltage corresponding to the offset control signal from the detected light signal and applying a gain to the subtracted signal.