Abstract: An electronic fitness device comprises a housing, a first optical transmitter, a second optical transmitter, an optical receiver, and a processor. The housing is positioned partly in contact with a user's skin. The first optical transmitter emits a first optical signal. The second optical transmitter emits a second optical signal. The optical receiver receives the optical signals and generates a first photoplethysmogram (PPG) signal resulting from the received first optical signal and a second PPG signal resulting from the received second optical signal. The processor receives the PPG signals, determines a pressure metric value based on a characteristic of a waveform of the first PPG signal and a characteristic of a waveform of the second PPG signal, and determines a pressure compensation factor based on the determined pressure metric value, the first wavelength corresponding to the first optical signal and the second wavelength corresponding to the second optical signal.

Abstract: An electronic wearable device comprises a housing configured to contact a user's skin, first and second modulators, first and second optical transmitters coupled with the first and second modulators, an optical receiver, and receive processing circuits. The first and second modulators output a first electronic signal having a first carrier frequency and a second electronic signal having a second carrier frequency. The first optical transmitter outputs a first optical signal having the first carrier frequency into the user's skin. The second optical transmitter outputs a second optical signal having the second carrier frequency into the user's skin. The optical receiver receives the optical signals from the skin as a broadband signal. The receive processor circuits output a first photoplethysmogram signal corresponding to the first optical signal based on the first carrier frequency and a second photoplethysmogram signal corresponding to the second optical signal based on the second carrier frequency.

Abstract: A wrist-worn electronic device comprises a housing including a bottom wall configured to contact a user's wrist, an optical transmitter and receiver assembly and a processor. The optical transmitter and receiver assembly comprises a first optical transmitter array, a first optical receiver, a second optical transmitter array, and a second optical receiver. The first and second optical transmitter arrays transmit a plurality of first and second optical signals, respectively, that pass through a user's skin. The first and second optical receivers receive the first and second optical signals that travel along a first signal path and a second signal path, respectively, that are both substantially parallel to an arm axis of the user. The processor is configured determine physiological information about the user based on one or both of first and second electronic signals corresponding to the first and second optical signals.