Physiological characteristic determination based on signal correlation
Embodiments relate generally to a wearable device implementing a touch-sensitive interface in a metal pod cover and/or bioimpedance sensing to determine physiological characteristics, such as heart rate. According to an embodiment, a method includes receiving an amplified signal including a portion of the physiological-related signal component including data representing a physiological characteristic, the amplified signal being derived from bioimpedance signal based on an impedance value of a tissue, and identifying a magnitude of a portion of the physiological-related signal component. Also, the method can compare the magnitude of the portion against another magnitude of a data model (e.g., in a time-domain) to form a matched value. Also, the method can determine a confidence indicator value representative of a degree of likelihood that the matched value is representative of the physiological characteristic, and determining a value of the physiological characteristic based on the matched value and the confidence indicator value.
1 . A method comprising:
receiving an amplified signal including a portion of the physiological-related signal component that includes data representing a physiological characteristic, the amplified signal being derived from bioimpedance signal based on an impedance value of a tissue;
identifying a magnitude of the portion of the physiological-related signal component;
comparing the magnitude of the portion of the physiological-related signal component against another magnitude of a data model for the physiological characteristic in a time-domain to form a matched value;
establishing the matched value of the physiological characteristic;
determining a confidence indicator value representative of a degree of likelihood that the matched value is representative of the physiological characteristic;
determining a value of the physiological characteristic based on the matched value and the confidence indicator value.
2 . The method of claim 1 , wherein determining the value of the physiological characteristic comprises:
determining one or more of a heart rate, a respiration rate, a galvanic skin resistance value, data representing an affective state or mode, an amount of energy expenditure and an amount of calories expended.
3 . The method of claim 1 , wherein identifying the magnitude of the portion of the physiological-related signal component comprises:
identifying the magnitude during a window of time.
4 . The method of claim 1 , wherein comparing the magnitude of the portion of the physiological-related signal component against the another magnitude of the data model comprises:
identifying a peak magnitude of the portion of the physiological-related signal component.
5 . The method of claim 4 , wherein identifying the peak magnitude comprises:
performing an autocorrelation operation on data representing the data model and the portion of the physiological-related signal component.
6 . The method of claim 1 , further comprising:
determining a time interval between the magnitude and the another magnitude; and
calculated a rate indicative of the value of the physiological characteristic.
7 . The method of claim 6 , wherein determining the confidence indicator value comprises:
validating the rate is within a range of valid rates associated with the physiological characteristic.
8 . The method of claim 7 , wherein validating the rate is within the range of valid rates comprises:
validating the rate over the time interval is within a range of valid heart rates associated with a heart rate as the physiological characteristic.
9 . The method of claim 1 , further comprising:
adapting a value of a signal-to-noise ratio to form an adapted value of the signal-to-noise ratio based on the bioimpedance signal being based on the impedance value of the tissue.
10 . The method of claim 9 , further comprising.
characterizing the adapted value of the signal-to-noise ratio to form a characterized value of the signal-to-noise ratio.
11 . The method of claim 11 , wherein determining the confidence indicator value comprises:
validating the characterized value of the signal-to-noise ratio.