Continuous preparation, rereferencing and filtering

Prepare the continuous checkpoint

The first step writes a channel-oriented continuous .TAW recording. For BioSemi, reference weights in the sensor configuration determine the rereference; channel naming alone does not set the reference. With multiple reference channels, their weighted sum is subtracted.

Check the logged channel/weight terms and retained channels. An all-zero reference definition leaves BioSemi data unreferenced and produces a warning. A removed physical reference or an excluded channel can change the channel count. The adjacent .qecfg describes the resulting geometry and order.

A rereferenced BioSemi recording commonly becomes <recording>_r.TAW. The _r is a processing-history marker, not a separate data format.

Keep ICA training filters separate

When ICA correction is enabled, the minimally processed checkpoint supplies both a temporary filtered training copy and the broadband data used for component subtraction. The corrected continuous result is <recording>_r.ica.TAW.

Training-only filters and an optional training-epoch baseline do not become standard ERP filters. Configure the two filter families separately.

Standard ERP/ERF filters

Standard filtering follows accepted ICA correction, or continuous preparation when ICA is disabled. Configure the desired temporal filters and inspect their responses. Every enabled temporal filter must be designed for the recording’s actual sample rate. A mismatch stops processing rather than being corrected by implicit resampling.

Direct-design second-order sections (SOS) are available for IIR filtering; legacy full-vector processing remains a separate realization. Filter order, coefficients, realization and source provenance matter for reuse, not just the cut-off number in the filename.

For example, a filtered checkpoint may be named <recording>_r.ica.fl40.fh0.05.TAW. The abbreviated tags are useful labels, not a complete description of its filter response.

Reuse and storage

EMEGS preserves the minimally processed recording and accepted broadband ICA correction as independent prerequisites. Compatible final filtered recordings can be loaded directly without repeating every intermediate filter.

A missing processing-settings snapshot can trigger a compatibility-path warning: the filename and recording structure may be usable, but exact filter/source provenance cannot be verified. Do not interpret that warning as verified equivalence. Archive and rebuild if that uncertainty is unacceptable.

Use the previewed filter-pruning tool rather than deleting arbitrary files. See file safety and cleanup.