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BangleApps/apps/hrmmar/README.md

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hrmmar: Add fft elimination algorithm to remove MA The fft with size=256 is calculated over a window of 8 seconds with step size 2 seconds. Sample rate of acceleration (12.5Hz) and PPG sensor (25Hz) is unchanged, so the algorithm runs with 12.5Hz. Generally the maximum peak in fft spectrum in an interval of -5..+10BPM of last one is used. The low fft resolution limits the accuracy to ~3BPM, but mean error is ~5-10BPM. If firmware reports confidence >= 90% its value is used.
2022-11-27 18:05:40 +00:00
# HRM Motion Artifacts removal
Measurements from the build in PPG-Sensor (Photoplethysmograph) is sensitive to motion and can be corrupted with Motion Artifacts (MA). This module allows to remove these.
## Settings
* **MA removal**
Select the algorithm to Remove Motion artifacts:
hrmmar: bthrm compatibility - Disable when bthrm is active - Enable fft elim as default
2023-03-19 07:26:51 +00:00
- None: No Motion Artifact removal.
- fft elim: (default, *experimental*) Remove Motion Artifacts by cutting out the frequencies from the HRM frequency spectrum that are noisy in acceleration spectrum. Under motion this can report a heart rate that is closer to the real one but will fail if motion frequency and heart rate overlap.