Note: This article is intended for HRV researchers and professionals performing advanced data analysis. There is no information in these raw data sets that is applicable to the average user’s daily coherence practice.
When exporting session data from emWave Pro or emWave Pro Plus for use in third-party statistical software (such as Kubios or Excel), you will encounter two distinct formats of Inter-Beat-Interval (IBI) data.
1. Live IBI Data
Live IBI data represents the true, asynchronous timing of the heart.
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Structure: It consists of a series of 4-byte integers.
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Frequency: One value is recorded for every pulse/heartbeat detected.
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Timing: The “start time” for each data point is the exact moment the pulse wave was drawn by the sensor.
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Best Use: Use Live IBI when you need to analyze the specific, beat-to-beat variability of the heart (HRV) for research purposes.
2. Sampled IBI Data
Sampled IBI data provides a synchronized, uniform version of the heart rhythm.
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Structure: It consists of a series of 4-byte integers.
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Frequency: Data is sampled exactly every 500 milliseconds.
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Count: The total number of data points in this set will always be exactly twice the number of seconds in the session duration.
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Best Use: This format is helpful for graphing or for analysis tools that require a fixed, linear sampling rate rather than irregular intervals.
Summary Comparison
| Feature | Live IBI | Sampled IBI |
| Data Points | 1 per heartbeat | 2 per second (every 500ms) |
| Timing | Asynchronous (Real-time) | Synchronous (Fixed-rate) |
| Primary Use | High-precision HRV research | Graphing and linear analysis |