Patent ID: 9717424
Date: 2017-08-01
CPC Classifications: A61B

Claim:
1. A fitness monitor for monitoring a cardiac signal of a user, the device comprising: an emitter configured to output light toward skin of the user; an emitter driver configured to cause the emitter to output light at one of a plurality of intensity levels; a receiver configured to receive a reflection of the transmitted light and generate a light intensity signal based on the received reflection; a photometric front end configured to receive the light intensity signal and generate a photoplethysmogram (PPG) signal based on the light intensity signal, the PPG signal including a cardiac signal of the user; a memory device configured to store a reference value characterizing performance of the photometric front end based on a variability of the PPG signal output from the photometric front end during idle operation; and a processor communicatively coupled to the emitter, the receiver, photometric front end and the memory device, the processor configured to: