Heart rate monitor with time varying linear filtering
AssigneeGarmin Switzerland GmbH
InventorsPaul R. MacDonald, Christopher J. Kulach
Life of this patent
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Abstract
A system, method, and device for monitoring a cardiac signal of a user includes an emitter (LED) for transmitting light toward skin of the user, a receiver (photodiode) for receiving a reflection of the transmitted light and generating a light intensity signal, and a processor configured to generate a photoplethysmogram (PPG) signal based on the light intensity signal. The PPG signal includes a cardiac component, a motion component and a respiratory component. An inertial sensor provides a motion signal to the processor based on sensed movement of the device and one or more time-variant filters are configured by the processor to filter the PPG signal to isolate the cardiac component of the PPG signal based on determined filter coefficients.
Claims29
A fitness monitor for monitoring a cardiac signal of a user, the device comprising:
- an emitter configured to transmit light toward skin of the user;
- a receiver configured to receive a reflection of the transmitted light and provide a photoplethysmogram (PPG) signal based on the received reflection of the transmitted light, the PPG signal including a cardiac component and a motion component;
- an inertial sensor configured to provide a motion signal based on sensed movement of the fitness monitor;
- a time-variant filter configured to isolate a component of the PPG signal based on filter coefficients corresponding to a desired component of the PPG signal, and
- a processor coupled to the emitter, the receiver, the inertial sensor and the time-variant filter, the processor configured to:
- determine one or more frequencies associated with the motion signal;
- transform the PPG signal to the frequency domain;
- identify, in the frequency domain, the cardiac component in the PPG signal based on the determined one or more frequencies of the motion signal and the transformed PPG signal;
- determine filter coefficients based on the identified cardiac component in the PPG signal;
- configure the time-variant filter with the determined filter coefficients;
- filter, in the time domain via the time-variant filter, the motion component from the PPG signal to isolate the identified cardiac component;
- and
- calculate, in the time domain, the time between successive cycles of the isolated cardiac component of the PPG signal.
A fitness monitor for monitoring a cardiac signal of a user, the device comprising:
- an emitter configured to transmit light toward skin of the user;
- a receiver configured to receive a reflection of the transmitted light and provide a photoplethysmogram (PPG) signal based on the received reflection of the transmitted light, the PPG signal including a cardiac component and a motion component;
- an inertial sensor configured to provide a motion signal based on sensed movement of the fitness monitor;
- a time-variant filter configured to isolate a component of the PPG signal based on filter coefficients corresponding to undesired components of the PPG signal, and
- a processor coupled to the emitter, the receiver, the inertial sensor and the time-variant filter, the processor configured to:
- determine one or more frequencies associated with the motion signal and the PPG signal provided during a first period,
- identify the motion component in the PPG signal for the first time period based on the determined one or more frequencies of the motion signal and the PPG signal,
- filter, via the time-variant filter, the identified motion component from the PPG signal provided during a second time period to isolate the cardiac component of the PPG signal for the second time period, and
- calculate, in the time domain, the time between successive cycles of the isolated cardiac component of the PPG signal for the second time period.
A fitness monitor for monitoring a cardiac signal of a user, the device comprising:
- an emitter configured to transmit light toward skin of the user;
- a receiver configured to receive a reflection of the transmitted light and provide a photoplethysmogram (PPG) signal based on the received reflection of the transmitted light, the PPG signal including a cardiac component and a motion component;
- an inertial sensor configured to provide a motion signal based on sensed movement of the fitness monitor;
- a time-variant filter configured to isolate a component of the PPG signal based on filter coefficients corresponding to a desired component of the PPG signal, and
- a processor coupled to the emitter, the receiver, the inertial sensor and the time-variant filter, the processor configured to:
- determine one or more frequencies associated with the motion signal and the PPG signal provided during a first time period,
- identify the cardiac component in the PPG signal for the first time period based on the determined one or more frequencies of the motion signal and the PPG signal,
- filter, via the time-variant filter, the PPG signal provided for a second time to isolate the cardiac component of the PPG signal for the second time period based on the identified cardiac component, and
- calculate, in the time domain, the time between successive cycles of the isolated cardiac component of the PPG signal for the second time period.
Dependencies are inferred from the claim text.