Single Channel ECG Visualizer

NOT INTENDED FOR MEDICAL USE
Designed as a visualizer to complement an Analog Devices AD8232 acquisition setup

Getting Started

• Try it out with the test data by selecting either Short, Long, or Arrythymia (L) in Acquisition > Raw Samples
• Changes to any settings can be applied by clicking Parse ECG on the top right corner of the page.
• Reopen this guide anytime by pressing Help beside Parse ECG.

Interacting with the Visualizer

• Primary view (top): Measurement calipers can be set with Left Click
• Scroll view (bottom), where Mouse Wheel adjusts the zoom, and Left Click + Drag moves the Primary view
• Save the views anytime with Right Click and Save Image As…

Acquisition

Sample Format
Raw ECG data is stored as a ASCII file in the format of
Time (ms):Raw ADC data,Time (ms):Raw ADC data, etc…

This makes it simple to work with Arduino (etc) with code like

Serial.print(millis());
Serial.print(":");
Serial.print(analogRead(adcPin));
Serial.print(",");
delay(1);

Interpreter

• Voltage Range & ADC Range: Maps the raw ADC data to its respective voltages
• Tick Divisions: Sets the spacing intervals (ms) for major and minor tick markers
• Invert Signal: Inverts the signal on the voltage axis

Signal Processing

Subtract Signal
Subtracts a sine wave from the signal. This may be useful for removing very well defined 50/60Hz noise in a short capture. However some trial and error is required to align the phase and amplitude.

Mains Reduction Filter
A more general low-pass filter which may also be used to remove mains noise. As this applies a LPF, the signal will appear sluggish (especially sharp transitions). This should be used as a last resort if a cleaner capture cannot be made.

Baseline Correction
Aligns signal to a centerline derived from a strong LPF. Useful for longer captures where the signal may “wander” on the vertical (voltage) axis.

R-R Analysis

Very experimental feature to detect and mark R in the QRS complex, as well as to indicate ! where an R was expected but could not be found. Statistics (Interval, Detected Beat count, Rate) are also displayed after processing.

• Disable Filter / Analysis (Global): Filters are all enabled by default (in Signal Processing) and unchecking this disables all filters and analysis.
• Plot RR Detection Lines (Diagnostics): Shows the processed signal after LPF/squaring for diagnosing software issues.

Known Issues

• Resizing the page can break things. Please refresh if this occurs.
• The samples look like Einthoven’s Lead II but I’m not entirely sure either.

jg
Twitter: @jg_lim