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Signal Visualization Interpretation Guide

This guide helps you understand ECG and PPG visualization charts, quickly identify normal vs abnormal patterns, and make the best use of our visualization tools.

ECG waveform visualization​

Standard display format​

Axis settings​

Horizontal axis (time):
- Standard: 25 mm/s (each small grid = 0.04s, each large grid = 0.20s)
- High speed: 50 mm/s (used for arrhythmia analysis)
- Low speed: 12.5 mm/s (used for long-term recording)

Vertical axis (voltage):
- Standard: 10 mm/mV (1mV = 10 small grids)
- Half gain: 5 mm/mV (when signal is too large)
- Double gain: 20 mm/mV (when signal is too small)

Grid background​

Single-lead display​

Use a typical ECG display (e.g., Lead II) to interpret P/QRS/T waves and the RR interval to compute heart rate.

Key markings:
✓ P wave: atrial depolarization
✓ QRS complex: ventricular depolarization (most prominent)
✓ T wave: ventricular repolarization
✓ RR interval example: 0.8s → 75 BPM

Multi-lead synchronized display​

For a 12-lead ECG, the system shows standard limb leads and precordial leads simultaneously so you can localize abnormal regions more accurately.

Advantages:

  • ✅ Observe the heart from different perspectives
  • ✅ More accurate localization of abnormal areas
  • ✅ More comprehensive diagnostic information

Rhythm strip display​

For long-term monitoring (compressed display), a rhythm strip helps you see overall heart rhythm trends and occasional anomalies that may require zooming in.

PPG waveform visualization​

Standard display format​

PPG waveforms typically show:

  • A clear systolic peak
  • A visible dicrotic feature (dicrotic notch/peak)
  • A stable baseline

Heart rate can be estimated from the PP interval:

Heart rate = 60 / PP interval (seconds)

Dual-wavelength PPG display (SpO2)​

For oxygen saturation measurement, show red (660nm) and infrared (940nm) channels and compute the ratio R to estimate SpO2.

PPG during motion​

During exercise, motion artifacts can make it harder to identify pulse peaks. Common mitigations include accelerometer compensation, adaptive filtering, and multi-sensor fusion.

Normal vs abnormal pattern comparison​

ECG examples​

Common abnormal patterns include:

  • Sinus tachycardia / bradycardia
  • Atrial fibrillation (absence of clear P waves; irregular baseline)
  • Premature ventricular contractions (wide QRS; possible compensatory pause)
  • ST-segment changes (ischemia/infarction patterns)

PPG examples​

PPG can reflect changes in pulse amplitude and waveform shape, which may correspond to:

  • Reduced dicrotic feature (possible arterial stiffness)
  • Low perfusion (smaller amplitude)
  • Irregular rhythm patterns

Real-time monitoring display​

Continuous rolling waveform​

Realtime views typically include:

  • Live ECG waveform stream
  • Auto scaling
  • Signal quality indicators
  • Abnormal alerts

Trend and histogram views​

Trend charts (e.g., 24-hour heart rate trends) help you verify circadian rhythm and monitor responses during activity/sleep. Histograms summarize the distribution of heart rate values.