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edr reads the signal and annotation files specified by record and annotator, and writes another annotation file, which is a copy of the input annotation file except that the num field of each beat annotation is replaced by an EDR sample.
If the beat annotations are not located at the QRS peaks, it will be necessary to set the window limits (the offsets relative to the annotations between which the raw measurements for the EDR are taken), using the -d option. By default, edr behaves as if the option -d -0.04 0.04 has been given (in other words, measurements are taken over an 80 ms window beginning 40 ms (.04 seconds) before the annotation, and ending 40 ms after the annotation); this default is reasonable if the QRS annotations have been placed on or near the QRS peaks or centroids. If edr is supplied with annotations generated by sqrs, or another method that places the annotations near the PQ junction (the beginning of the QRS complex), the option -d 0 0.08 is recommended.
For ECGs sampled at relatively low rates (e.g., 100-128 Hz, as is common for many long-term ECG recordings), it may be advantageous to base the EDR on the T-wave rather than the QRS complex, by choosing a window such as -d -0.08 0.28 or -d -0.12 0.32 (for annotations placed at the QRS peaks or PQ junctions respectively), since this permits an axis estimation based on a larger number of samples. Note that the use of a negative value for dt1, as in these examples, allows the beginning of the EDR measurement window to be placed after the QRS annotation.
It may be necessary to set and export the shell variable WFDB (see setwfdb(1) ).
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Updated 26 January 2018