If you notice your emWave2 running by itself—blinking or even changing coherence levels when no one is using it—your device is experiencing a phenomenon known as “Ghosting.”
While this behavior may look like a malfunction, it is actually a normal byproduct of the device’s high-sensitivity engineering. Below is a detailed explanation of why this happens and how to manage it.
Resolving emWave2 Pulse Indicator Ghosting
What is “Ghosting”?
“Ghosting” occurs when the emWave2 appears to detect a pulse and run a session automatically without being connected to a user. It may even cycle through coherence lights as if it were tracking a real person.
Why Does This Happen?
This is a result of the aggressive automatic gain function created by HeartMath engineers.
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Sensitivity vs. Accuracy: To work with a wide range of pulse strengths and skin types, the sensor is designed to be incredibly sensitive. All engineering efforts to eliminate ghosting resulted in a loss of sensitivity for actual users, so the high-sensitivity design was maintained to ensure the best experience during real sessions.
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High Sample Rates: To accurately capture Heart Rate Variability (HRV), the emWave2 samples data at 125 to 350 samples per second. For comparison, standard heart rate monitors only sample at 20–40 samples per second. This higher frequency makes the device more prone to picking up random background frequencies when the sensor is not covered.
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Closed-Loop Feedback: When the sensor is not in contact with a finger or ear, it aggressively hunts for a signal by boosting LED output and adjusting gain settings. It can occasionally “lock on” to low-level reflections from its own plastic surface or external light sources, appearing “coherent” to the internal software.
Is My Device Defective?
No. Ghosting is a normal response from the emWave2 electronics. It does not harm the unit, nor does it indicate a defect in the hardware.
How to Start a Normal Session
As soon as you begin a session, the device will override the “ghost” signal:
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Place your thumb on the sensor (or connect the ear clip).
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You will initially see a small red light over the blue pulse light for a few seconds.
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The red light will quickly fade away, leaving only the blue light blinking in time with your actual pulse.
Quick Summary
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The Cause: High sensitivity and high sample rates designed to capture professional-grade HRV data.
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The Trigger: External light or reflections on the sensor’s plastic surface while uncovered.
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The Fix: Simply place your thumb on the sensor or use the ear clip; the device will immediately prioritize your actual pulse.
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