Incorrect Heart Rate Detection Due to High Video Quality
This issue can occur when high-quality video captures too much movement, especially from the heart. This can confuse the software and cause misinterpretation of the heartbeat signal.
Check the Activity Plot
In the Activity plot:
- A represents the true heartbeat waveform.
- B and C are narrower peaks making up A. These peaks originate from different parts of the heart — B from wall movement and C from the blood flow immediately following it.
Inspect the Power Spectrum
The first peak (~105 bpm) corresponds to the general heart rhythm (A). The second, stronger peak results from counting both B and C, effectively doubling the frequency. DanioScope detects this second peak as the heart rate because it has the highest power.
Why the Error Happens
The secondary wave (C) has an amplitude nearly equal to the primary wave (B), making it appear as a valid second heartbeat. This doubles the frequency in the analysis.
How to Fix It
Reduce the Heart area to better isolate the desired movement (B). A smaller Heart area limits detection to the heart wall motion, avoiding interference from the blood flow.
In the comparison above:
- Left: Heart area too large, causing inaccurate detection.
- Right: Properly focused Heart area yields correct results.
Tip: For consistent results, use the same magnification level when recording your videos and draw similarly sized Heart areas.