Returns the prefilter of signal edfsignal ("HP:0.1Hz", "LP:75Hz N:50Hz", etc.).
prefilter=edf_get_prefilter(path, edfsignal)
: string containing the path and name of the file
: Minimum value is 1.
:prefilter of signal edfsignal
Returns the prefilter of signal edfsignal ("HP:0.1Hz", "LP:75Hz N:50Hz", etc.).