# US 12,004,845 B2 · Pulse spectroscopy > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,004,845 B2 - Document ID: US12004845B2 - Status: Granted - Kind: B2 - Application number: 17/492,382 - Filed: 2021-10-01 - Published: 2022-01-27 - Granted: 2024-06-11 - Earliest claimed: 2017-05-04 - Assignees: Garmin Switzerland GmbH - Applicants: Garmin Switzerland GmbH - Inventors: Christopher J. Kulach; Paul R. MacDonald - Web page: https://patentgrep.com/patent/US12004845B2 ## CPC - A61B 5/02427: {Details of sensor} - A61B 5/02416: {using photoplethysmograph signals, e.g. generated by infrared radiation (A61B5/14552 takes precedence)} - A61B 5/02438: {with portable devices, e.g. worn by the patient} - A61B 5/14535: {for measuring haematocrit} - A61B 5/14542: {for measuring blood gases (A61B5/14551 takes precedence)} - A61B 5/14552: {Details of sensors specially adapted therefor} - A61B 5/4875: {Hydration status, fluid retention of the body} - A61B 5/681: {Wristwatch-type devices} - A61B 5/6824: {Arm or wrist} - A61B 5/7207: {of noise induced by motion artifacts} - A61B 5/7214: {using signal cancellation, e.g. based on input of two identical physiological sensors spaced apart, or based on two signals derived from the same sensor, for different optical wavelengths} - A61B 5/7246: {using correlation, e.g. template matching or determination of similarity} - A61B 5/725: {using specific filters therefor, e.g. Kalman or adaptive filters (specific diagnostics methods using using bioelectric or biomagnetic signals A61B5/316)} - A61B 5/7253: {characterised by using transforms} - A61B 5/7257: {using Fourier transforms} - A61B 5/7278: {Artificial waveform generation or derivation, e.g. synthesizing signals from measured signals} - A61B 5/7282: {Event detection, e.g. detecting unique waveforms indicative of a medical condition (cough events A61B5/0823; seizures A61B5/4094; sleep apnoea A61B5/4818)} - A61B 5/0004: {characterised by the type of physiological signal transmitted} - A61B 2503/10: Athletes - A61B 2505/09: Rehabilitation or training - A61B 2560/0462: Apparatus with built-in sensors - A61B 2562/0238: Optical sensor arrangements for performing transmission measurements on body tissue - A61B 2562/0242: for varying or adjusting the optical path length in the tissue - A61B 2562/04: Arrangements of multiple sensors of the same type - A61B 2562/043: in a linear array - A61B 2562/046: in a matrix array - A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D) ## Abstract An electronic fitness device comprises a first optical transmitter, an optical receiver, and a processing element. The first optical transmitter is configured to transmit a first optical signal and a second optical signal. The optical receiver is configured to receive the first and optical signals and to generate first and second photoplethysmogram (PPG) signals resulting from the received optical signals. The processing element is configured to control the first optical transmitter to transmit the first optical signal the second optical signal, receive the first and second PPG signals from the optical receiver and compare them, identify a common cardiac component present in the first and the second PPG signals based on the comparison, determine a signal filter parameter based on the common cardiac component, and generate first and second cardiac components from the first and second PPG signals, respectively, based on the signal filter parameter. ## Claims ### Claim 1 An electronic fitness device comprising: a housing including a bottom wall adapted to be positioned over the skin of a user; a first optical transmitter positioned along the bottom wall, the first optical transmitter configured to transmit a first optical signal having a first wavelength; a second optical transmitter positioned along the bottom wall, the second optical transmitter configured to transmit a second optical signal having a second wavelength; an optical receiver positioned along the bottom wall, the optical receiver configured to receive the first and the second optical signals modulated by the skin of the user and generate first and second photoplethysmogram (PPG) signals resulting from the received first and the received second optical signals, respectively, each optical signal containing a cardiac component of the user; and a processing element in electronic communication with the first optical transmitter, second optical transmitter and the optical receiver, the processing element configured to: control the first optical transmitter to transmit the first optical signal during a first period of time and the second optical signal during a second period of time, receive the first and the second PPG signals from the optical receiver, compare the first and the second PPG signals, identify a common component present in the first and the second PPG signals based on the comparison, determine a signal filter parameter based on the common component, generate a first cardiac component from the first PPG signal based on the signal filter parameter, generate a second cardiac component from the second PPG signal based on the signal filter parameter, and determine blood-related physiological information based on the first and the second cardiac component; wherein a first path from the first optical transmitter to the first optical receiver along which the first optical signal travels is substantially different from a second path from the second optical transmitter to the first optical receiver along which the second optical signal travels. ### Claim 2 (depends on 1) The electronic fitness device of claim 1, further comprising at least a first signal filter and a second signal filter, and wherein the processing element: generates the first cardiac component by filtering the first PPG signal with the first signal filter using the signal filter parameter, and generates the second cardiac component by filtering the second PPG signal with the second signal filter using the signal filter parameter. ### Claim 3 (depends on 1) The electronic fitness device of claim 1, further comprising a third optical transmitter positioned along the bottom wall, the third optical transmitter configured to transmit a third optical signal, wherein the processing element is further configured to: control the third optical transmitter to transmit the third optical signal during a third period of time, receive the third PPG signal from the optical receiver, and generate a third cardiac component from the third PPG signal based on the signal filter parameter. ### Claim 4 (depends on 1) The electronic fitness device of claim 1, wherein the processing element is further configured to utilize the signal filter parameter to generate a transfer function that is applied to each of at least a first signal filter and a second signal filter, and wherein the processing element: generates the first cardiac component by filtering the first PPG signal with the first signal filter, and generates the second cardiac component by filtering the second PPG signal with the second signal filter. ### Claim 5 (depends on 1) The electronic fitness device of claim 1, wherein the signal filter parameter is a spectral parameter of the common component, and wherein the processing element: generates the first cardiac component by filtering the first PPG signal with the first signal filter using the spectral parameter, and generates the second cardiac component by filtering the second PPG signal with the second signal filter using the spectral parameter. ### Claim 6 (depends on 1) The electronic fitness device of claim 1, wherein the signal filter parameter is a common waveform associated with the common component and the processing element: generates the first cardiac component by comparing the first PPG signal with the common waveform, and generates the second cardiac component by comparing the second PPG signal with the common waveform. ### Claim 7 (depends on 1) The electronic fitness device of claim 1, wherein the processing element is further configured to: determine values of a plurality of filter coefficients for each of at least a first signal filter and a second signal filter using the signal filter parameter, each signal filter being a discrete-time, multi-tap time delay line filter with each tap configured using one of the plurality of filter coefficients, and periodically update the filter coefficients based on a feedback signal based on a difference between the first cardiac component and the second PPG signal. ### Claim 8 (depends on 1) The electronic fitness device of claim 1, wherein the signal filter parameter is one of a filter coefficient, a waveform associated with the identified common cardiac component, or a spectral parameter of the identified common cardiac component. ### Claim 9 (depends on 1) The electronic fitness device of claim 1, wherein the determined blood-related physiological information is a pulse-oximetry level. ### Claim 10 (depends on 1) The electronic fitness device of claim 1, wherein the first period of time partially overlaps with the second period of time. ### Claim 11 An electronic fitness device comprising: a housing including a bottom wall adapted to be positioned over the skin of a user; a first optical transmitter positioned along the bottom wall, the first optical transmitter configured to transmit a first optical signal having a first wavelength; a second optical transmitter positioned along the bottom wall, the second optical transmitter configured to transmit a second optical signal having a second wavelength; a first optical receiver positioned along the bottom wall, the first optical receiver configured to receive the first optical signal modulated by the skin of the user and generate a first photoplethysmogram (PPG) signal resulting from the received first optical signal; a second optical receiver positioned along the bottom wall, the second optical receiver configured to receive the second optical signal modulated by the skin of the user and generate a second PPG signal resulting from the received second optical signal; and a processing element in electronic communication with the first optical transmitter, second optical transmitter, the first optical receiver and the second optical receiver, the processing element configured to: control the first optical transmitter to transmit the first optical signal during a first period of time and the second optical signal during a second period of time, receive the first PPG signal from the first optical receiver, receive the second PPG signal from the second optical receiver, compare the first and the second PPG signals, identify a common component present in the first and the second PPG signals based on the comparison, determine a signal filter parameter based on the common component, generate a first cardiac component from the first PPG signal based on the signal filter parameter, generate a second cardiac component from the second PPG signal based on the signal filter parameter, and determine blood-related physiological information based on the first and the second cardiac component; wherein a first path from the first optical transmitter to the first optical receiver along which the first optical signal travels is substantially different from a second path from the second optical transmitter to the first optical receiver along which the second optical signal travels. ### Claim 12 (depends on 11) The electronic fitness device of claim 11, further comprising at least a first signal filter and a second signal filter, wherein the processing element: generates the first cardiac component by filtering the first PPG signal with the first signal filter using the signal filter parameter, and generates the second cardiac component by filtering the second PPG signal with the second signal filter using the signal filter parameter; and wherein the first period of time partially overlaps with the second period of time. ### Claim 13 (depends on 11) The electronic fitness device of claim 11, further comprising a third optical transmitter positioned along the bottom wall, the third optical transmitter configured to transmit a third optical signal, wherein the processing element is further configured to: control the third optical transmitter to transmit the third optical signal during a third period of time, receive the third PPG signal from one of the first optical receiver and the second optical receiver, and generate a third cardiac component from the third PPG signal based on the signal filter parameter. ### Claim 14 (depends on 11) The electronic fitness device of claim 11, further comprising: a third optical transmitter positioned along the bottom wall, the third optical transmitter configured to transmit a third optical signal; and a third optical receiver positioned along the bottom wall, the third optical receiver configured to receive the third optical signal modulated by the skin of the user and generate a third PPG signal resulting from the received third optical signal; wherein the processing element is further configured to: control the third optical transmitter to transmit the third optical signal during a third period of time, receive the third PPG signal from the third optical receiver, and generate a third cardiac component from the third PPG signal based on the signal filter parameter. ### Claim 15 (depends on 11) The electronic fitness device of claim 11, wherein the processing element is further configured to utilize the signal filter parameter to generate a transfer function that is applied to each of at least a first signal filter and a second signal filter, and wherein the processing element: generates the first cardiac component by filtering the first PPG signal with the first signal filter, and generates the second cardiac component by filtering the second PPG signal with the second signal filter. ### Claim 16 (depends on 11) The electronic fitness device of claim 11, wherein the signal filter parameter is a spectral parameter of the common component, and wherein the processing element: generates the first cardiac component by filtering the first PPG signal with the first signal filter using the spectral parameter, and generates the second cardiac component by filtering the second PPG signal with the second signal filter using the spectral parameter. ### Claim 17 (depends on 11) The electronic fitness device of claim 11, wherein the signal filter parameter is a common waveform associated with the common component and the processing element: generates the first cardiac component by comparing the first PPG signal with the common waveform, and generates the second cardiac component by comparing the second PPG signal with the common waveform. ### Claim 18 (depends on 11) The electronic fitness device of claim 11, wherein the determined blood-related physiological information is a pulse-oximetry level.