Good EEG data starts with good electrode contact. The recordings page shows real-time signal quality metrics during active recording so you can adjust headset fit before capturing important data.
Signal quality is calculated from the standard deviation of voltage values over a 1-second sliding window (256 samples at 256 Hz). Lower deviation means cleaner, more stable signal.
A per-channel bar chart updating every second. Each bar is colored by the quality rating above. Aim for mostly green bars before starting your real recording.
A top-down head diagram (nose at top) showing electrode positions from the 10-20 system. Each electrode dot is colored by its current quality rating, giving you a spatial sense of where contact is poor.
Mostly green, one yellow: Acceptable for most analyses. ZUNA can clean mild artifacts
Red or gray channels: Adjust the headset. Red means high noise; gray means no contact at all
ZUNA can remove many artifacts, but it works best when the raw signal has decent contact quality. Starting with poor signal quality means losing neural information that can’t be recovered.
