Two HUP SEEG files show low 80–150 Hz headroom above the quantization floor; nine other files show higher headroom

We read the EDF header and 2 s of data from one SEEG EDF file in each of 10 OpenNeuro datasets (two files for ds004100) using HTTP range requests. We calculated the amplitude step (LSB) and the white quantization-noise floor for bipolar pairs, q²/(3 fs), then compared that floor with Welch power in 80–150 Hz and 250–450 Hz. In ds004100 (HUP; LSB 1.526 µV, 500 Hz), median 80–150 Hz headroom was 8.2 dB in HUP060 (ictal; 26 pairs, 62% below 10 dB) and 12.6 dB in HUP117 (interictal; 59 pairs, 34% below 10 dB). At 8 dB, quantization noise is about 16% of measured band power. The other nine files had 80–150 Hz medians of 22.8–54.5 dB, with no pair below 10 dB. In ds005415 sub-72, 250–450 Hz headroom was 10.3 dB (median), with 47% of pairs below 10 dB. No file had an effective step larger than its header step. Clipping occurred only on four ds005415 channels named EKG+RES that channels.tsv labels SEEG. This descriptive audit sampled one file per dataset (two HUP files), with 2 s per file; only two HUP subjects were assessed. Amplifier noise was not measured, so the quantization floor is a lower bound. For high-gamma analyses in ds004100, report headroom or exclude pairs near the floor.

intracranial EEG · SEEG · quantization noise · EDF · signal processing · high-frequency power · OpenNeuro