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This program analyzes one signal of a PhysioBank-compatible record, detecting and annotating rising and falling step changes. Typically this can be useful for finding transitions in a recorded digital stimulus or event marker signal, especially if the signal is noise-contaminated (as may occur if it has been recorded via an analog-to-digital converter).
tup is the threshold for detecting a rising step change (annotated as ’R’), and tdown is the threshold for detecting a falling (’F’) step change. This program requires that tup > tdown. Using its -m option, set tup to a value significantly greater than tdown to avoid false detections of transitions due to noise in the signal. Noise spikes that still cause false detections can often be avoided by median-filtering the signal (see mfilt(1) ) before using it as input to this program.
It may be necessary to set and export the shell variable WFDB (see setwfdb(1) ).
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Updated 28 May 2015