Compute time-varying cHPI amplitudes.
Raw
Raw data with cHPI information.
float
Minimum time step to use.
float
Time window to use to estimate the amplitudes, default is 0.2 (200 ms).
int
The external order for SSS-like interfence suppression. The SSS bases are used as projection vectors during fitting.
Changed in version 0.20: Added ext_order=1
by default, which should improve
detection of true HPI signals.
float
Start time of the raw data to use in seconds (must be >= 0).
float
End time of the raw data to use in seconds (cannot exceed data duration).
str
| int
| None
Control verbosity of the logging output. If None
, use the default
verbosity level. See the logging documentation and
mne.verbose()
for details. Should only be passed as a keyword
argument.
dict
The time-varying cHPI coil amplitudes, with entries “times”, “proj”, and “slopes”.
Notes
This function will:
Get HPI frequencies, HPI status channel, HPI status bits,
and digitization order using _setup_hpi_amplitude_fitting
.
Window data using t_window
(half before and half after t
) and
t_step_min
.
Use a linear model (DC + linear slope + sin + cos terms) to fit sinusoidal amplitudes to MEG channels. It uses SVD to determine the phase/amplitude of the sinusoids.
In “auto” mode, t_window
will be set to the longer of:
Ensures that the frequency estimate is stable.
Ensures that neighboring frequencies can be disambiguated.
The output is meant to be used with compute_chpi_locs()
.
New in version 0.20.
mne.chpi.compute_chpi_amplitudes
#Extracting and visualizing subject head movement