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 ).
- -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.
It may be necessary to set and export the shell variable
WFDB (see setwfdb(1)
).
mfilt(1)
George B. Moody (george@mit.edu).
http://www.physionet.org/physiotools/wfdb/app/stepdet.c
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