Heart rate algorithm
How does Apple Watch calculate "beats per minute" or BPM?
method 1. Count pressure peaks for a period, then BPM = Count x (1 minute/period). Discount period time occurring out of range due to "missing beat", caused by PVC, PAC, etc.
Method 2. Over a time period, 15, 30, or 60 seconds average the peak to peak beat interval, discounting abnormal interval times caused by PVC, PAC, etc. State the BPM as avg X with a standard deviation of Y.
Depending on the method and the discount logic my own BPM can be stated from 50 to 80 on the same data! In my case I have Missed beats per minute that run from zero to 20 for long periods. Example for the last 2 hours my "missed beats per minute" are running 16 MBPM every minute! My BPM ALSO as reported by Apple Watch runs between 65 and 85, all sitting, NOT during exercise.
my conclusion: Apple's "Heart Rate" report needs an accurate definition of what it is reporting. A single number now reported is Not accurate!
method 1. Count pressure peaks for a period, then BPM = Count x (1 minute/period). Discount period time occurring out of range due to "missing beat", caused by PVC, PAC, etc.
Method 2. Over a time period, 15, 30, or 60 seconds average the peak to peak beat interval, discounting abnormal interval times caused by PVC, PAC, etc. State the BPM as avg X with a standard deviation of Y.
Depending on the method and the discount logic my own BPM can be stated from 50 to 80 on the same data! In my case I have Missed beats per minute that run from zero to 20 for long periods. Example for the last 2 hours my "missed beats per minute" are running 16 MBPM every minute! My BPM ALSO as reported by Apple Watch runs between 65 and 85, all sitting, NOT during exercise.
my conclusion: Apple's "Heart Rate" report needs an accurate definition of what it is reporting. A single number now reported is Not accurate!