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Name

stepdet - single-channel step change detector

Synopsis

stepdet -r record [ options ... ]

Description

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).
-h
Print a brief usage summary.
-H
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.

Environment

It may be necessary to set and export the shell variable WFDB (see setwfdb(1) ).

See Also

mfilt(1)

Authors

George B. Moody (george@mit.edu).

Source

http://www.physionet.org/physiotools/wfdb/app/stepdet.c


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Updated 28 May 2015