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stepdet - single-channel step change detector


stepdet -r record [ options ... ]


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).

Options include:

-a annotator
Write annotations to the specified annotator (default: ’steps’)
-f time
Begin at the specified time in record (default: the beginning of record).
Print a brief usage summary.
Read the signal files in high-resolution mode (default: standard mode). These modes are identical for ordinary records. For multifrequency records, the standard decimation of oversampled signals to the frame rate is suppressed in high-resolution mode (rather, all other signals are resampled at the highest sampling frequency).
-m tup tdown
Specify thresholds for transitions from low to high (tup, default: 550) and from high to low (tdown, default: 450).
-s signal
Specify the signal (number or name) to be used for step detection (default: 0).
-t time
Process until the specified time in record (default: the end of the record).

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) ).

See Also



George B. Moody (


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Updated 28 May 2015