EstimateTimeshift¶
Estimate the time shift between two streams in the given data, in seconds.
This quantifies by how much (in s) the second stream is delayed relative to the first stream. This uses a correlation-based method which therefore requires that the two streams contain one or more signal components that can be linearly transformed into each other. Note that this node requires some carefully prepared input data, which should have at least the following processing steps applied to it: resampling to same nominal sampling rate, removal of irrelevant channels (e.g., trigger channels etc), possible reduction to a moderate channel count (max 64 per stream), zero-median re-referencing, replacement of non-finite data points, band-pass filter to frequency band of interest, trimming of all streams to same time range, and interpolation onto the same time base using eg nearest-neighbor method. Version 0.9.0
Ports/Properties¶
data¶
Data to process.
shift¶
Estimated time-shift.
corr¶
Maximum correlation value.
streams¶
List of stream names to compare. If not given, the data must have exactly two non-empty signal streams.
method¶
Method to use for the estimation: 'cca' for canonical correlation analysis (which can handle multi-channel data but is slower), and 'corr' is the regular single-channel correlation (requires each stream to have only one channel).
max_delay¶
Maximum delay that will be considered, in seconds.
max_iter¶
Maximum number of iterations for the estimation.
blocksize¶
Block size in seconds for robust estimation. If one of the modalities is not very robust (e.g., can drop out), this can be used to estimate the delay over smaller stretches of data, and then take a robust mean of the maximum correlation values. The length of these stretches (the block size) should be chosen to roughly reflect the duration over which a modality may be stable, but should not be too short, especially not if the streams have more than a few channels due to ambiguity.
trim_proportion¶
Proportion of the data to trim when using robust estimation (via the blocksize). This represents the fraction of the time that a modality may be unreliable.
verbose¶
Display lag in console with every tick.
set_breakpoint¶
Set a breakpoint on this node. If this is enabled, your debugger (if one is attached) will trigger a breakpoint.
metadata¶
User-definable meta-data associated with the node. Usually reserved for technical purposes.